Patent Publication Number: US-2011073104-A1

Title: Parabolic trough solar energy collection system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to (1). U.S. Provisional Patent Application Ser. No. 61/046,327, filed Apr. 18, 2008, titled “Support Structure for Solar Energy Collection System;” (2). U.S. Provisional Patent Application Ser. No. 61/128,198, filed May 19, 2008, titled “Support Structure for Solar Energy Collection System;” (3). U.S. Provisional Patent Application Ser. No. 61/081,655, filed Jul. 17, 2008, titled “Thermal Energy Receiver;” (4). U.S. Provisional Patent Application Ser. No. 61/192,079, filed Sep. 12, 2008, titled “Solar Collector Assembly “SopoRack””; (5). U.S. Provisional Patent Application Ser. No. 61/195,291, filed Oct. 3, 2008, titled “Concentrated Solar Trough “SopoFlare””; and (6) U.S. Provisional Patent Application Ser. No. 61/192,086, filed Sep. 12, 2008, titled “Automated Solar Collector Cleaning “SopoWash””, all of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Solar energy can provide an environmentally friendly source of energy that does not rely on extraction of fossil fuels and that contributes relatively less to global warming and to related environmental problems than do fossil fuel-based energy sources. In addition, in many cases solar energy can be captured and used locally and thus reduce requirements for transportation or importation of fuels such as petroleum. 
     Solar energy may be captured, for example, by a collector that absorbs solar radiation and converts it to heat, which may then be used in a variety of applications. Alternatively, solar radiation may be captured by a collector which absorbs solar radiation and converts a portion of it directly to electricity by photovoltaic methods, for example. Mirrors or lenses may be used to collect and concentrate solar radiation to be converted to heat or electricity by such methods. 
     Solar energy collectors have been designed and manufactured to numerous specifications. Many areas, especially those remote from a major power grid, require an economical source of energy for e.g., process heat or electricity generation and air conditioning. 
     BRIEF SUMMARY OF THE INVENTION 
     In one variation, a trough solar energy collector comprises a support assembly for supporting one or more solar energy collecting panels, at least one solar energy collecting panel, the collecting panel being secured to the support assembly by at least one panel-retaining strip; and a collector tube positioned to receive light reflected by the collecting panel. The support assembly further comprises a plurality of longitudinal rails, a first transverse rib and a second transverse rib both secured to the plurality of longitudinal rails, wherein each of the ribs has a shape approximating a chord of a cylindrical or parabolic surface; and a first end assembly and a second end assembly both secured to the plurality of longitudinal rails; wherein a first of the plurality of longitudinal rails is positioned at an apex, minimum, or vertex of the cylindrical or parabolic surface; 
     In one variation, a trough solar energy collector comprises a support assembly for supporting one or more solar energy collecting panels, at least one solar energy collecting panel, and a collector tube positioned to receive light reflected by the collecting panel. The support assembly further comprises a plurality of longitudinal rails, a first transverse rib and a second transverse rib both secured to the plurality of longitudinal rails, wherein each of the ribs has a shape approximating a chord of a cylindrical or parabolic surface; and a first end assembly and a second end assembly both secured to the plurality of longitudinal rails; wherein a first of the plurality of longitudinal rails is positioned at an apex, minimum, or vertex of the cylindrical or parabolic surface. 
     In one variation, a trough solar energy collector comprises a support assembly for supporting one or more solar energy collecting panels, at least one solar energy collecting panel, and a collector tube positioned to receive light reflected by the collecting panel. The support assembly further comprises a plurality of longitudinal rails, a first transverse rib and a second transverse rib both secured to the plurality of longitudinal rails, wherein each of the ribs has a shape approximating a chord of a cylindrical or parabolic surface; and a first end assembly and a second end assembly both secured to the plurality of longitudinal rails; wherein each of said first and second transverse ribs comprises at least two rib sections; said rib sections forming part of said cylindrical or parabolic surface, said first and second rib sections having portions overlapping one another at an apex, minimum, or vertex of said cylindrical or parabolic surface. 
     In one variation, a linear array of trough solar energy collectors comprises a plurality of trough solar energy collectors, a motor having a shaft, a first drive shaft with one end attached to the motor shaft, and at least one sprocket assembly comprising a first sprocket attached to one trough collector and a second sprocket attached to the first drive shaft; wherein the first and second sprocket are coupled with a chain and disposed substantially within the same plane. 
     In one variation, a method of assembling a trough solar energy collector comprises assembling a support assembly for supporting a plurality of solar energy collecting panels, securing a plurality of solar energy collecting panels to the support assembly by a plurality of transverse panel-retaining strips, securing an edge of the collecting panels to a transverse end of the support assembly with two longitudinal strips; and placing a collector tube positioned to receive light reflected by the collecting panels; the collector tube being supported by a plurality of stanchions disposed upon the panel-retaining strips. In another variation, the two longitudinal strips are cowlings. In another variation, the two cowlings are “U”-shaped. 
     In one variation, a kit for making a support assembly for a trough solar energy collector comprise four identical end plates, a plurality of longitudinal rails having a cross-sectional shape and area, and a plurality of ribs having openings of about the cross-sectional shape and area of the plurality of longitudinal rails. 
     In one variation, a rack to assemble a trough solar energy collector comprises a base having two longitudinal sides; each of the longitudinal sides having about the same length as the longitudinal rail of the trough solar energy collector, and a plurality of brackets mounted along each of the longitudinal sides at pre-determined locations; the brackets configured to receive an end of the transverse rib of the trough solar energy collector. In another variation, the positions of the brackets can be adjusted. 
     In one variation, a rack to assemble a trough solar energy collector according to comprises a base having a hollow region; the base having sufficient surface to support four sides of the trough solar energy collector with the solar energy collecting side facing downward; and a removable inner rack configured to place in the hollow region of the base and to support the trough solar energy collector with the solar energy collecting side facing upward. 
     In one variation, a method of utilizing a trough solar energy collector to generate steam comprise assembling a trough solar energy collector and heating water contained in the collector tube by light reflected by the solar energy collecting panels to generate steam. 
     In one variation, a method of utilizing a trough solar energy collector generate steam comprises assembling a trough solar energy collector, exchanging heat between a working fluid contained in the collector tube heated by light reflected by the solar energy collecting panels and water to generate steam. 
     Provided herein is a frame assembly that may be used to construct solar energy collection and conversion systems. The frame assembly may be configured to provide a trough solar thermal energy collector, a Fresnel solar thermal energy collector, and/or a photovoltaic solar energy collector, for instance. The frame assembly comprises a plurality of longitudinal rails, a plurality of transverse ribs which individually attach to two or more rails, and a plurality of transverse end arms secured to the rails that may cooperate to provide an assembly that is light, inexpensive to manufacture, and easy to assemble. 
     Also provided herein is a method of supporting a solar energy conversion surface. The method comprises forming a support surface comprised of ribs which may be formed from rib pieces and supported and secured at their first ends by a common rail and supported at their second ends by a common rail, and placing the solar energy conversion surface upon the ribs which distribute the weight of the solar energy conversion surface into the common rails. 
     Further, provided herein are various methods of making a framework for a solar energy conversion system as well as a method of making a solar energy conversion system. In one instance, the method comprises providing a frame assembly as discussed herein, and attaching thereto one or more solar energy collecting panels. In another instance, the method comprises assembling a plurality of identical rails, identical ribs, and identical end pieces into a frame assembly, and securing one or more solar energy collecting panels to the frame assembly. 
     Table 1 discloses various combinations of features for different support assemblies and solar energy collection systems formed with such support assemblies. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  illustrates one variation of a partially completed support assembly. 
         FIG. 2  illustrates another variation of a partially assembled support assembly. 
         FIG. 3A  depicts one variation of a transverse rib. 
         FIG. 3B  depicts one variation of a rib plate. 
         FIG. 4  illustrates an end section coupled to a rib section, according to one variation. 
         FIGS. 5A and 5B  show two views, an aerial perspective view  5 A and a view from the solar energy collecting panel side  5 B, of a rib section formed of two rib plates. 
         FIG. 6  illustrates another variation of a partially assembled support assembly. 
         FIG. 7  illustrates an end assembly formed of two interdigitatedly connected end sections. 
         FIGS. 8A and 8B  depict one variation of a mount collar and  FIG. 8C  illustrates two end sections connected each other with the mount collar in  FIG. 8A . 
         FIGS. 9A and 9B  depict a cowling disposed between two panel locks and over an end-rail as well as guy wires and turnbuckles to adjust tension on the guy wires, according to one variation. 
         FIG. 10  illustrates housing panels of a support assembly being secured by an end panel lock and one solar energy collecting panel secured by a center panel lock, according to one variation. 
         FIG. 11  illustrates one variation of a transverse rib assembly formed of two interdigitatedly connected rib sections, wherein the rib assembly is connected to two center rails and one center panel lock. 
         FIG. 12  illustrates housing panels, sectioned longitudinal rails, and a solar energy collecting panel in place over a support assembly to form a partially completed solar energy collector, according to one variation. 
         FIG. 13  depicts one variation of a parabolic-shaped solar energy collector. 
         FIGS. 14-16  illustrate variations of the mount collar and bearing structures that may be used to hold one or more support assemblies. 
         FIGS. 17-20  depict ganged parabolic solar energy collectors driven by a common drive system and details of a drive system, according to one variation. 
         FIG. 21  illustrates panel-retaining strips to secure solar energy collecting panels, according to one variation. 
         FIGS. 22-23  illustrate variations of stanchions that support a collector tube. 
         FIGS. 24 and 25  illustrate variations of a parabolic-shaped solar energy collector in various stages of construction. 
         FIG. 26  illustrates a trough collector, according to one variation. 
         FIGS. 27 and 28  show end caps and housing panels, respectively, for a support assembly, according to one variation. 
         FIG. 29  depicts one variation of a stanchion assembly. 
         FIG. 30  illustrates the stanchion assembly in  FIG. 29  with a collector tube. 
         FIGS. 31A and 31B  depict one variation of a mount collar configured to support a collector tube. 
         FIG. 32  illustrates a parabolic-shaped solar energy collector with a collector tube covered by transparent sleeves. 
         FIG. 33  illustrates details of a collector tube covered by a slotted sleeve and a movable cover, according to one variation. 
         FIG. 34  illustrates one variation of a track assembly to guide the motion of the movable cover in  FIG. 33 . 
         FIGS. 35A to 35C  illustrate three positions of a track assembly with respect to a stationary tube when the solar energy collector tracks the sun, according to one variation. 
         FIG. 36  illustrates one variation of the track assembly positioned by a stanchion. 
         FIG. 37  illustrates a slotted collector tube sleeve with a complementary cover 
         FIG. 38  illustrates a row of solar energy collector and rows of partially finished stands to support solar energy collectors, according to one variation. 
         FIG. 39  shows details of an end solar energy collector in a row of collectors, according to one variation. 
         FIG. 40  illustrates a method to secure a transverse rib to a longitudinal rail, according to one variation. 
         FIGS. 41 and 42  illustrate a method to secure solar energy collecting panels and housing panels with an inner cowling and an outer cowling, according to one variation. 
         FIG. 43  illustrates a transverse rib assembly with bent edge, according to one variation. 
         FIG. 44  illustrates a transverse panel-retaining strip, according to one variation. 
         FIG. 45  illustrates a method to attach two draft shaft tubes, according to one variation. 
         FIG. 46  illustrates a small-diameter sprocket attached to a drive shaft tube, according to one variation. 
         FIGS. 47A to 47D  illustrate a large-diameter sprocket attached to the end assembly of a trough solar energy collector, according to one variation. 
         FIG. 48  illustrates a chain tensioner assembly configured to tension the sprocket chain, according to one variation. 
         FIGS. 49A to 49E  illustrate one exemplary trough solar energy collector, according to one variation. 
         FIGS. 50 and 51  illustrate two exemplary assembly racks configured to facilitate assembling of a trough solar energy collector, according to one variation. 
         FIG. 52  illustrates a method to mount a collector tube stanchion on a transverse panel-retaining strip, according to one variation. 
         FIG. 53  schematically shows an exemplary layout of a row of trough solar energy collectors, according to one variation. 
         FIG. 54  illustrates a drive stand for trough solar energy collector, according to one variation. 
         FIG. 55  illustrates a method to attach a mount tube to a mount collar of a trough solar energy collector, according to one variation. 
         FIGS. 56A and 56B  illustrate two variations of an automated washing system. 
         FIGS. 57A to 57F  illustrate an assembly rack, according to one variation. 
         FIGS. 58A to 58C  illustrate another assembly rack, according to one variation. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Various aspects of the inventions disclosed herein may be understood better by reference to the following discussion in conjunction with the figures, which form a part of this specification. The discussion of particular examples does not limit the scope of the invention, and the discussion is provided only to aid in understanding various aspects of the inventions disclosed herein. It should be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly indicates otherwise. 
     Also described herein are parabolic trough solar energy collectors that may track the sun movement and concentrate incident solar radiation onto a heat collection element (HCE) positioned along the collector&#39;s focal line. A trough solar energy collector may comprise, solar energy collecting panels, which reflect and concentrate the incident solar radiation to the heat collection element, a heat collection element configured to collect the thermal energy reflected by collecting panels, and a support assembly configured to support collecting panels and the heat collection element. The trough solar energy collector may further comprise a drive system that may drive the trough collector to track the sun during the day. Various components of a trough solar energy collector that may be present individually or in any combination in a collector are discussed in detail below. 
     I. Support Assembly 
       FIG. 1  illustrates one variation of a support assembly  100  of the trough collector. This support assembly  100  is discussed here only for the purpose of aiding an understanding of the various parts. The support assembly  100  comprises a generally parabolic shape. This support assembly  100  may be formed by a plurality of longitudinal rails ( 101 - 106  are shown), a plurality of transverse ribs ( 111 - 115 ), and/or two end assemblies ( 121  and  122 ). While not limiting the scope of the invention, the particular support assembly illustrated in  FIG. 1  may have a longitudinal length (e.g., the longitudinal distance between two end assemblies  121  and  122 ) of about 11 feet to about 13 feet, a height (e.g., the vertical distance between the uppermost point and the lowermost point of the end assembly  121  and  122 ) of about 1.5 feet to about 2 feet, and a width (the transverse distance between the leftmost point and the rightmost point of the end assembly  121  and  122 ) of about 5 feet to about 6 feet. Each of parts and components that form the support assembly  100  is discussed below in further detail, and it is to be understood that any of the variations of these pieces discussed herein may be used in the combinations specified in Table I. 
     A. Longitudinal Rails 
     Longitudinal rails ( 101 - 105 ) may extend the longitudinal length of a support assembly  100 , although some or all of the rails may extend only for part of the longitudinal length of the support assembly (while another structure such as a space-frame completes the support assembly). In the variation depicted in  FIG. 1 , the support assembly  100  could eventually have up to eight longitudinal rails, and six ( 101 - 106 ) of the longitudinal rails are illustrated in the figure. In other variations, a support assembly of the trough collector may have more than 8, for example, 10, 12, 14 or more, longitudinal rails. The disposition of longitudinal rails on each half of the trough may or may not by symmetric. Each longitudinal rail may individually be a single piece, such as a piece of tubing or pipe of e.g. circular cross-section, or a square cross-section or U-shaped channel, for instance. Alternatively, a longitudinal rail may be formed in pieces such as the pieces  107  and  108  illustrated in  FIG. 12  that e.g., screw together or press together to form one longitudinal rail or which have male-female portions that form an interference fit or which may be secured to one another using a weld, set-screw, bolt, or other fasteners. 
     The rails are substantially parallel or parallel to one another. For instance, during assembly, the rails may be substantially parallel and somewhat movable so that rails may be easily aligned to holes in ribs or end assemblies and these pieces fitted to the plurality of longitudinal rails. Rails may all be of the same length, or rails may differ in length. 
     A support assembly may have a single longitudinal rail or a plurality (e.g. two, three, or more) of center longitudinal rails at a center, vertex, or minimum point of the support assembly. The parabolically-shaped support assembly of  FIG. 1  and  FIG. 2  has two center longitudinal rails  101  and  102  at the minimum, center, vertex, or apex point of the support assembly. A plurality of longitudinal rails at the center, vertex, apex, or minimum point remove degrees of freedom of movement that transverse ribs might otherwise have if e.g., only one longitudinal rail is positioned at the center, vertex, or minimum of the support assembly during manufacturing. Assembly may be simplified by removing various degrees of freedom, where e.g., the ribs may rotate about a single longitudinal rail. A plurality of rails may also provide a support assembly with increased rigidity and/or strength. 
     As illustrated in  FIG. 1 , the support assembly of the trough collector may have one end longitudinal rail  103  or  104  at each transverse end of the trough. Each end  143  or  144  of an end longitudinal rail  103  or  104  is coupled to an end assembly  107  and  108  and a transverse rib  111  or a rib section. In one variation, the two end longitudinal rails  103  and  104  have larger outer diameter than other rails (e.g., the center rails  101  and  102  and rails  105  and  106  between an end rail and a center rail). The outer diameter of an end longitudinal rail may be about 1½″ whereas the outer diameter of other rails may be about 1″. In other variations, all longitudinal rails may have about the same outer diameter. In still other variations, the center rails may comprise larger outer diameter than other rails. The longitudinal rails may have any length and diameter as desired. 
     The longitudinal rails may be made from any suitable materials, such as plastic, metal or metal alloy, that provide sufficient structural support to the trough solar energy collector. In some variations, longitudinal rails may be formed of a polymer such as a rigid polymer having good impact strength. A polyolefin, polyamide, polyaromatic, polycarbonate, or other polymers may be used. Alternatively, rails may be formed of metal such as stainless steel or other metal that weathers well. Standard pipe such as stainless steel pipe that tolerates inclement weather may be used as or in forming longitudinal rails. In another variation, the longitudinal rails are extruded aluminum pipes. 
     B. Transverse Ribs 
     A transverse rib may be a single piece (e.g.,  300  in  FIG. 3A ) that will span all of the longitudinal rails, or a transverse rib may be formed of two or more rib sections  312  as depicted in  FIG. 3B  and  FIG. 4 . As illustrated in  FIG. 3A , a single piece transverse rib  300  may comprise two end holes  311 ,  312  that are configured to receive end longitudinal rails (e.g.,  103 ,  104  in  FIG. 1 ) of a support assembly. The rib  300  also comprises two center holes  312 ,  313  that are configured to receive center longitudinal rails (e.g.,  101  and  102  in  FIG. 1 ) located at a center, vertex, or minimum point of the support assembly. In some variations, a rib  300  may comprise more than one end hole and more than two center holes. The rib  300  may optionally comprise one or more holes between the end hole and the center hole(s)  314 - 317  to receive additional longitudinal rails (e.g.,  105  and  106  in  FIG. 1 ).  FIG. 3B  schematically illustrates one example of rib section  312  comprising two center holes  301  and  302 , one end hole  305  and two holes  303 ,  304  disposed therebetween. In some variations, a rib or rib section may comprise only one or more than two (e.g., three, four or more) center holes, depending in part on the number of longitudinal rails used at the center, vertex, or minimum point of the support assembly. The number of the holes between the end hole and the center holes may be only one or more than two (e.g., three, four, or more), depending in part the number of the longitudinal rails used in the support assembly. The holes between the end hole and center hole(s) may or may not be evenly spaced. In some variations, the rib or rib sections have holes not used in a finished support assembly (e.g.,  3801  in  FIG. 38 ). The holes may be of any diameter selected based in part upon the outer diameter of the corresponding longitudinal rails. The support assembly  100  in  FIG. 1  comprises five transverse ribs  111 - 115 . In other embodiment, a solar collector support assembly may comprise any of 2, 3, 4, 5, 6, 7, 8, 9, 10 or more transverse ribs. The number of transverse ribs may be selected based in part on the length of longitudinal rails to provide the amount of support to the solar energy collecting panels needed for the particular application. 
     A transverse rib  300  or a rib section  312  may be a single piece of metal, plastic or other material having a surface that has a shape this is generally parabolic or substantially arc-shaped. Transverse rib sections may be identical pieces that fit upon and affix to two or more longitudinal rails to form ribs that support solar energy collecting panels, as  601  in  FIG. 6  without its accompanying rib section on the opposite side of the support assembly. In other variations, a rib section may cooperate with an adjacent rib section (identical or not identical) on a different set of longitudinal rails to form a rib, as shown in  FIG. 6  by a rib comprising of two identical rib sections  602  and  603 . In such a variation, two rib sections  602 ,  603  may have an overlapped portion such that the center hole(s) of two rib sections are aligned to receive one or more center longitudinal rails  604  and  605 . As noted above, such design may reduce degrees of freedom of movement of the ribs or rib sections, thereby simplifying the assembling process. The rib sections  602  and  603  may be riveted, bolted, screwed, welded, glued, or otherwise adhered to each other. 
     Support surfaces on a rib section may be curved or flat. The support surfaces of a rib section may form a portion of a parabola, for instance. A surface of a rib that engages a solar energy collecting panel may be quite small, smaller than the width of the rib as measured from a point of contact with a solar energy collecting panel and perpendicular to the solar energy collecting panel. The width is sufficient to provide the rib with good rigidity against bending and/or shear forces. A rib surface that engages a solar energy collecting panel may have flanged portions that provide more surface area to support a collecting panel, or the surface may be no more than what is provided by the thickness of the materials used to form the rib. One example of at least partially flanged ribs or rib sections is illustrated in  FIG. 43 . 
     A transverse rib assembly  4300  in  FIG. 43  comprises two symmetrical rib sections  4301  and  4302 . Each rib sections (e.g.,  4301 ) is formed of a single plate with upper and lower edges (e.g.,  4303  and  4305 ) being bent to the same direction. The bent edge (e.g.,  4303 ) forms a substantially 90 degrees angle with the plane of the rib section (e.g.,  4301 ). The edge of a rib or a rib section may not be bent along the entire length of the rib or rib section. For example, in the example depicted in  FIG. 43 , the overlapped portions of the two rib sections  4301  and  4302  do not have a bent edge. In this way, the two rib sections  4301  or  4302  may be placed against each other to form a rib assembly  4300  without being separated by a bent edge in between. In other variations, the edge of a rib or a rib section may only be bent where contact surface or working surface may be needed. When the rib assembly  4300  is assembled with two rib sections  4301  and  4302 , the installer need to make sure that rib sections  4301  and  4302  are oriented in the correction direction, e.g., the edges of both rib sections  4301  and  4302  should extend to the same direction. The bent edges of a rib or a rib section provide contact surface between the rib or rib section and the solar energy collecting panels. They may also provide a working surface for attaching the rib or rib section to other parts of the solar energy collector without having to use spacers or cowlings. For example, a housing panel  4340  may be secured to the rib assembly  4300  by one or more rivets (e.g.,  4308 ) or other types of fasteners located on the lower edge (e.g.,  4306 ) of the rib assembly. In another example, a stanchion (not shown), which is configured to support a heat collector tube, may be attached to the rib assembly  4300  by one or more screws (e.g.,  4322  and  4324 ) or other types of fasteners located on the upper edge ( 4303  and  4324 ) of the rib assembly  4300 .  FIG. 43  shows a rib assembly formed of two rib sections with bent upper and lower edges. In other variations, a transverse rib with bent edges may be a single piece. 
     Two adjacent rib sections may be secured to one another to form one parabolic transverse rib by any suitable method or means. As shown in the example in  FIG. 43 , the two rib sections may or may not each have an unbent region in the overlapping region to be interlocked. Two or more rails inserted through holes in the overlapping region prevent the sections from pivoting, thereby forming a transverse rib that does not lose its parabolic or cylindrical shape during use. Other suitable ways to secure rib sections is to one another is to bend portions differently so that the edges abut. For example, the overlapping region of two rib sections may be bent in a fashion that permits one rib section to fit within the other rib section to interlock them in the overlapping region. The edges of the rib sections do not have to be bent to have two ribs sections coupled to one another. For example, there may be a slot in the overlapping region of two rib sections to form a keyway and a “key” consisting of a flat “T”-shaped piece of metal with a hole along the upright portion of the “T” may be inserted in the keyway and secured with e.g., a screw or a bolt to hold the rib sections rigidly so that they are not prone to pivoting. In still other variations, the overlapping portions of two rib sections may be secured to one another by two or more screws, rivets, bolts, adhesive, or other suitable fasteners in the overlapping regions of the rib sections, regardless whether or not one or more longitudinal rails pass through the overlapping regions. Any combination of these coupling means for securing rib sections to one another may be used. 
     In some variations, the rib or rib section may also have mounting holes (e.g.,  4330 ) that have a rim (e.g.,  4322 ) that provides a contact surface or working surface where the rib may be attached or affixed to the longitudinal rails. In one example as illustrated in  FIG. 40 , a transverse rib  4004  is secured to a longitudinal rail  4002  by a dimple  4008  on the rim  4006  around the mounting hole in the rib  4004 , created by tanging the rib  4004  to the rail  4002 . In other variations, the transverse ribs or rib sections may be attached or affixed by welding, bolting, pinning, riveting, using a friction or an interference fit or any suitable attachment technique known to those skilled in the art. Rims on a rib or a rib section may or may not be oriented in the same direction as the bent edges of the rib or rib section. The rim  4006  may be an annular member inserted into a mounting hole to provide interface between the rib  4004  and the longitudinal rail  4002 . This annular member may be attached to the mounting hole by welding, soldering or interference fit. 
     Securing ribs or rib sections to the longitudinal rails prevent the ribs or rib sections from being flexible in the longitudinal direction (e.g., the direction substantially parallel to the rotational axis of the trough collector). Two longitudinal rails passing through one transverse rib or an overlapping region of two rib sections at an apex, minimum, or vertex of the trough further remove degrees of freedom of movement of the ribs or rib sections so that the ribs or rib sections are not prone to pivoting around the rotational axis of the trough. In such a way, the support assembly comprised of only longitudinal rails and ribs or rib sections is rigid enough to preserve a parabolic shape, even without the use of other reinforcing structures (e.g., housing panels or guy-wires). Additionally or alternatively, ribs or rib sections may be secured to housing panels or solar collecting panels such that the ribs or rib sections are locked in place longitudinally. 
     A transverse rib (e.g.,  300  in  FIG. 3A ) or a rib section (e.g.,  312  in  FIG. 3B ) may be formed of two or more rib plates (e.g., parabolic or arc-shaped) that are interconnected to provide plural support surfaces in one rib or one rib section. The plates may be formed by e.g., stamping or otherwise cutting plates from metal sheet-stock or alternative material. The plates may be joined to one another by a number of means. In one instance, the plates may be joined directly to one another by e.g., welding, riveting, bolting, screwing, or adhering the plates to one another. The rib section may instead have spacers between the plates and be joined to one another by welding or adhering the plates to the spacers or riveting or bolting to or through the spacers. Cowling may also be present or added along an edge, such as by incorporating a “U”-shaped channel between plates that is bent to fit the rib curvature. The “U”-shaped channel forms a face along an edge of the rib or rib section into which fasteners such as rivets, bolts, screws, and the like may be secured. In some variations, cowlings may be present or added along both edges of a rib or a rib section. The rib plates may be identical, in which case both of the plates have plural holes through which longitudinal rails extend. If one or more spacers are placed between plates to form a rib section, spacers may be positioned away from the plural holes through which longitudinal rails extend. 
       FIGS. 5A and 5B  illustrate one example of a rib section  512  comprising two identical pieces of rib plates  501 ,  502  that are spaced by a U-shape cowling  505 . One or more spacers  503  may be disposed between the two plates  501 ,  502 . The plates  501 ,  502  and the cowling  505  are attached by welding, riveting or bolting to or through the spacers  503 . Alternatively or additionally, fasteners (e.g., rivets, screws, bolts) or other suitable attachment methods (e.g., welding or adhesives) may be used to attach the cowling directly to the surfaces of rib plates  501  and  502 . In the variation illustrated in  FIGS. 5A and 5B , the cowling  505  is only installed along the bottom edge (e.g., the side opposite to the solar energy collecting panel side) of the rib section  512 . In other variations, the cowling  505  may be installed along both edges of the rib section  502  to provide additional structural support. 
     In one variation, one rib section with multiple rib plates may be interdigitated with another rib section that is also formed of multiple plates to form one transverse rib.  FIG. 11  illustrates such an example. As shown in this figure, two rib sections  512  and  513  are interdigitated such that one rib plate  516  of rib section  513  is disposed between rib plates  514  and  515  of rib section  514 . Similarly, rib plate  515  of rib section  512  is disposed between rib plates  516  and  517  of rib section  513 . In this variation, both rib sections  512  and  513  are spaced by spacers (e.g.,  518 ). Two rib sections  512  and  513  are attached to each other at their overlapping lower portions by rivets  519  and  520 . In such fashion, the support surfaces of the two rib sections that support a solar energy collecting panels may be substantially but not completely aligned with one another, with a support surface of one rib section being offset from the support surface of its overlapping rib section by the width of the metal used to form the plates of the rib sections. 
     Alternatively, the rib plates may not be identical, and one or more plates used to form the rib section lacks structure that extends around the center longitudinal rails at the center, vertex, or minimum of the support assembly. In this manner, a first rib section may be fitted to center longitudinal rails so that the rib section extends to one side of the rails, and a second identical rib section may be fitted to these longitudinal rails to contact the first rib section in such a way that ( 1 ) the second rib section extends to the opposite side of the rails and ( 2 ) the first and second rib sections align to form a rib in which plates of the first rib section align closely or identically with the plates of the second rib section to form a rib. The identical rib sections slid onto longitudinal rails to face in opposite directions as discussed above are thus complementary and provide aligned or substantially aligned support surfaces on the rib sections. 
     A transverse rib, a rib section and/or a rib plate may be stamped or pressed from a sheet of e.g. stainless or galvanized steel, aluminum, or polymer. Alternatively, the rib, rib section and/or rib plate may be a molded piece. In variations where each rib section has at least a portion of its edge bent to about 90 degrees with respect to the plane of the rib section, two rib sections that are coupled to one another to form one transverse rib are not identical, but minor images of one another. However, rib sections with edges unbent may still be stamped, pressed or otherwise cut from a sheet of rib material (e.g., steel or aluminum) as identical pieces. After identical rib sections are cut, two rib sections may have their edges (e.g., a portion of or entire edge) bent in opposite directions and be coupled together to form one transverse rib. 
     A transverse rib may or may not have a flange at one or more holes through e.g. a center portion of a rib. If a flange is incorporated, the flange may be secured to a longitudinal rail. 
     As noted above, at least one of the longitudinal rails passes through openings in the ribs, and in some instances all of the rails pass through openings in the ribs. The ribs may be secured to the longitudinal rails using fasteners. Alternatively or additionally, the ribs may be secured to an outer skin or housing to provide a rigid structure. 
     In some variations, as depicted in  FIG. 3B , the upper side (e.g., the solar energy collecting panel side) of a rib section  312  may optionally have one or more notches  306 ,  308  at one or both of the ends of the rib section into which one or more longitudinal cross-bars may fit. The longitudinal cross-bar(s) may be used to clamp or otherwise secure the edges of one or more solar energy collecting panels. In some variations, the lower side (e.g., the side opposite to the solar energy collecting panel side) of a rib, a rib section or a rib plate may also have optional notches  307 ,  309  configured to receive one or more longitudinal cross-bars. These bars may be used to clamp or other wise secure the edges of one or more optional housing panels placed on the outside of the support assembly, which will be discussed in greater detail later.  FIG. 9B  illustrates one example of longitudinal cross-bars that are used to lock the solar energy collecting panels and/or optional housing panels. As shown in  FIG. 9B , two rib plates  1022  and  1024  of one rib section  1020  both have upper side notches (only one notch  1011  can be seen in this figure) that receive a longitudinal cross-bar  1014 . Another longitudinal cross-bar  904  may be used with the longitudinal cross-bar  1014  to clamp the edge of one or more solar collecting panels between the two bars  904  and  1014 . Two bars  904  and  1014  may be attached with rivets, screws, bolts or other suitable fasteners. In this depicted variation, rib plates  1022  and  1044  also have lower notches (only one notch  1001  can be seen in this figure) that receive a longitudinal cross-bar  1004 . Another longitudinal cross-bar  905  is used with the bar  1004  to clamp the edge of one or more optional housing panels between the two bars  905  and  1004 . The two bars  905  and  1004  are attached by rivets (e.g.,  1006 ) together. In the variation shown in this figures, the rib notch (e.g.,  1001  or  1011 ) is only deep enough to receive one longitudinal cross-bar (e.g.,  1004  or  1014 ). In other variations, the notch may be deep enough to fit two longitudinal cross-bars. In this depicted variation, a pair of longitudinal cross-bars is used to form a clamp to serve as a panel (e.g., solar energy collecting panels or optional housing panels) lock. In other variations, other forms of panel locks may be used. For example, one longitudinal cross-bar may be used beneath which the edge of a panel may be placed and secured by rivets, screws, bolts or other types of fasteners. In other variations, individual clamps, brackets or other suitable attachment members may be used as panel locks. 
       FIG. 11  illustrates one example of a panel lock at the center, vertex, or minimum point of the support assembly to secure the solar energy collecting panels. As illustrated in  FIG. 11 , a center longitudinal cross-bar  701  is disposed in the aligned notches  710 ,  712  on the four rib plates  514 - 517  that form two interdigitated rib sections  512 ,  513 . A solar collecting panel (not shown in this figures) may be placed in contact with the longitudinal cross-bar  701  (e.g., on top of the bar  710  or beneath the bar  701 ) to locate the collecting panel at the center, vertex, or minimum of the solar energy assembly. The collecting panel may be attached to the longitudinal cross-bar by one or more rivets  1101 , screws, bolts or other fasteners. Not shown in this figure, another longitudinal cross-bar  730  may be disposed in the notches (e.g.,  309  in  FIG. 3B ) on the lower side of rib sections to locate or secure one or more housing panels  720  on the outside of the support assembly. The rivets  1101  that are used to attach the rib sections  512  and  513  to the longitudinal cross-bar  701  may also be used to attach the rib sections  512  and  513  to the longitudinal cross-bar  730 , on the other side of the support assembly. In other variations, additional set of fasteners may be used. As discussed later, the housing panels may provide structural integrity by being attached to ribs and/or longitudinal cross-bars to locate the ribs and provide resistance to forces that may flex or torque the support assembly. The housing panels may also or instead be decorative. 
     In some variations, the solar collecting panels and/or optional housing panels are not secured to the support assembly by a panel lock. In one variation, an end cowling may be used to attach the rib or rib section, the end longitudinal rails, the solar collecting panel and/or the housing panel together. Such design may simplify assembling process and reduce manufacturing cost. The securing mechanism with cowlings will be discussed in further detail in the section where solar energy collecting panels and optional housing panels are discussed. 
     C. End Assembly 
     As shown in  FIG. 1 , a support assembly  100  may also have end assemblies  121 ,  122  which provide further rigidity to the support assembly, especially if the support assembly is curved. The end assemblies may triangulate longitudinal ends of the structure assembly  100  to provide increased rigidity and resistance to flexure and/or torsion. 
     An end assembly can be formed in the same manner ribs or rib sections are formed, e.g., by stamping or otherwise cutting the end plate from sheet-metal (e.g., aluminum) or other material. An end assembly can be a single piece of material such as metal stamped from sheet-stock or other material, so that the end plate has a generally “T”- or “Y”-shaped structure as illustrated. The “T”- or “Y”-shaped structure can have plural cut-outs in the base of the “T” or “Y” to receive center longitudinal rails at the center, vertex, or minimum of the support assembly. Each arm of the “T” or “Y” has additional cut-outs to receive longitudinal rails. 
     An end assembly  121  can also be formed using two sections  107  and  108  that each have a generally “L”-shaped structure as illustrated in  FIG. 1 . In this instance, the two arms  107  and  108  are identical and are positioned together during assembly to provide a generally “T”- or “Y”-shaped structure when the support assembly  100  is viewed from the side.  FIG. 4B  illustrates one embodiment of an “L”-shaped end section  107 . The “L”-shaped section  107  has plural cutouts  141  and  142  in one leg (e.g., the short leg  412 ) of the “L” configured to receive plural center longitudinal rails at the center/vertex/apex of the support assembly  100 . The other leg (e.g., long leg  411 ) of the “L” may have a single cutout  143  to receive an end longitudinal rail (e.g., an end longitudinal rail  103  of the assembly  100 ). There may be another cut-out  421  at the vertex of the “L”-shaped section, which is configured to receive a mount collar (e.g.,  702  in  FIG. 7 ) used to couple two end sections together. In some variations, a transverse rib (e.g.,  111  in  FIG. 1 ) may transversely span from one end of the “T” or “Y”-shaped end assembly to the other end, with the bottom holes at the center, vertex, or minimum of the parabolic rib aligned with the cutouts at the bottom of the vertical leg of the “T” or “Y”-shaped end assembly, thereby forming a triangulated structure that provides mechanical strength and/or rigidity to the support assembly  100 . In other variations as illustrated in  FIG. 4A , one rib section  312  may span from one end of the “L”-shaped end section to the other, also forming a triangulated structure. In such variations, an identical triangulated structure may be formed extending to the opposite direction in the plane of the end assembly. 
       FIG. 6  illustrates another variation of an end assembly  610  comprising of two identical end sections  612  and  622 . In addition to the cutouts (e.g.,  613 - 615  of the end section  612 ) configured to receive longitudinal rails (e.g.,  604 - 606 ), each end section may comprise a plurality cutouts along both sides of the “L” (e.g.,  617 - 620 ). These cutouts may be designed to receive additional parts of a support assembly. For example, the cut cutout  619  may be designed to receive a mount collar, which will be discussed in greater detail below. In other variations, additional cutouts may be used for alignment purpose during manufacturing. 
     An end assembly may also be formed of pieces in a manner as discussed above for rib sections and as illustrated in  FIG. 7 . For example, two or more end plates with a “T” or a “Y” shape may be superimposed and attached to one another directly or through spacers, with or without a cowling or other filler plate, to form an end assembly. Two or more end plates with an “L” shape may form an end section in the similar fashion. In some variations as illustrated in  FIG. 7 , two “L”-shaped end sections  602  and  603  may be placed adjacent one another to form an end assembly with two sides of the “L” overlapped and the cutouts on the sides aligned. If spacers are used, “L”-shaped end sections may be interdigitated so that there is little offset in the sections of the “T”- or “Y”-shaped structure formed by placing two identical “L”-shaped end sections  602  and  603  immediately adjacent one another as depicted in  FIG. 7 , for instance. In the depicted embodiment, cowlings  711  and  712  are used in both end sections  602  and  603  to provide rigidity to the end assembly. Cowlings may be placed anywhere between the two end pieces of an end assembly or an end section. For example,  FIG. 7  illustrates cowlings  711  and  712  placed along the upper edge of the long sides of two “L”-shaped end section  602  and  603 .  FIG. 38  illustrates cowlings  3811  and  3812  placed along the inner edges of both long and short sides of an “L”-shaped end section  3810 . 
     An end assembly may abut a transverse rib at an end of the support assembly as shown in  FIGS. 1 ,  2 , and  6  for instance. As illustrated in  FIG. 1 , the arms and base of the “T”- or “Y”-shaped end assembly  121  directly contact a surface of the transverse rib  111 . Cutouts (e.g.,  141 - 144 ) on the end assembly  111  and cutouts on the transverse rib are aligned together to receive end longitudinal rails  103  and  104  and/or center longitudinal rails  101  and  102 . In some variations, the end assembly  121  and the rib  111  may both be attached or affixed to longitudinal rails. In other variations, the end assembly and the rib may be attached by rivets, screws, bolts, welding, adhesives or other suitable attachment methods. In some variations, a transverse rib may be interdigitated with an end assembly of the support assembly where each is formed to have spaced portions amenable to interdigitation. In some variations, an end assembly may not abut a transverse rib. For example, an end assembly may be only secured to one or more longitudinal rails to provide structural support at a longitudinal end of the support assembly. 
     In some variations, two “L”-shaped end sections or end sections may be connected through a mount collar, which inserts through the cutout located at the bend of the “L”. The mount collar may aid in holding two “L”-shaped end sections together to form an end assembly. The variations of the mount collar will be discussed in greater detail later. 
     An end assembly need not be “T”- or “Y”-shaped. An end section need not be “L”-shaped. In some variations, an end assembly or an end section may have additional arms configured to connect the end assembly to the end rib to provide additional rigidity to the support assembly. An end section may be a solid or perforated plate to which longitudinal rails and other parts are attached, for instance. 
     D. Longitudinal Cross-Bar 
     As noted above, one or more longitudinal cross-bars may optionally be placed in the notches of longitudinally adjacent rib sections or ribs to serve as panel (e.g., solar energy collecting panels or optional housing panels) locks. End cross-bars may be provided at one transverse end of a rib or rib assembly or at both ends. The end cross-bars may therefore help clamp the solar collecting panel along one or two edges of the panel to secure it to the support assembly, and the longitudinal cross-bars may also provide a gap of sufficient size that a solar energy collecting panel can expand from absorbed solar energy that heats the panel.  FIG. 9B  illustrates two end cross-bars  904  and  1014  configured to secure solar collecting panels. Also as noted above, one or more cross-bars (such as  905  and  1004  in  FIG. 9B ) may be used to clamp or secure optional housing panels placed on the outside of the support assembly. 
     As noted before, in addition to the end cross-bars, an optional center cross-bar  701  may be positioned near the middle, apex, or minimum of the support assembly as illustrated in  FIG. 7  to secure another end of a collecting panel if the panel only spans from an end rail to an center rail or to secure a mid portion of a collecting panel if the panel spans from an end rail to another end rail. Another center cross-bar may be positioned near the middle, apex, or minimum of the support assembly but on the outside of the support assembly, which is configured to attach, clamp or otherwise externally secure the housing panel to the support assembly. 
     In some variations, a cross-bar  701  may be supported on spanner bars  703  that span center longitudinal rails  101  and  102  and are attached to at least one rail by e.g., a rivet  705 . Cross-bar  701  provides a surface underneath of which solar energy collecting panels such as minor panels may be lodged and to which panels may be attached. In some variations, a rivet may join an outer housing panel, an outer center cross-bar, a spanner bar, an inner-cross-bar, and an inner solar collecting panel together. 
     A solar energy collecting panel such as a mirror panel may optionally be secured to a rib or a rib section by e.g. riveting, bolting, gluing, clamping or otherwise engaging the surface of the rib or rib section. In some variations, the collecting panels are secured to the bent edges of the rib or rib sections. In other variations, the collecting panels are secured to the surfaces of the cowlings put in between rib plates. In some instances, the longitudinal cross-bars are sufficient to locate the solar collecting panels to the support assembly. In some instances, a single rivet  1101 , bolt, or screw as illustrated in  FIG. 11  may be used to lock the longitudinal cross-bar (e.g.,  701 ), solar energy panel, rib, and optional outer housing panel together at each rib. 
     E. End Cowlings 
     Use of longitudinal cross-bars is optional. In some variations, the solar energy colleting panels or optional housing panels may be secured to the support assembly by other types of attachment methods.  FIGS. 41 and 42  illustrate one example to use an inner cowling and an outer cowing to secure both solar energy collecting panels and optional housing panels to the support assembly. In  FIG. 41 , a support assembly comprising a plurality of longitudinal rails (e.g.,  4104 ,  4105 ), a plurality of transverse ribs (e.g.,  4106 ) and two end assemblies  4110  and  4112  has been partially assembled. A housing panel has been placed at the lower side of the support assembly and attached to the ribs by a plurality of rivets (e.g.,  4109 ). A U-shape inner cowling  4102  may be placed upon the end longitudinal rail  4104  with its inner surface may engaging the bent edges (e.g.,  4107 ) of the plurality of ribs (e.g.,  4106 ). The lower side of the “U”-shaped cowling  4102  should be placed between the housing panel  4108  and the transverse ribs (e.g.,  4106 ). Once the solar energy collecting panels  4120  are installed as illustrated in  FIG. 42 , an outer cowing  4104  may be placed outside of the inner cowling  4102  with the edges of the solar collecting panels  4120  and the housing panels  4108  clamped in between. 
     In some variations, transverse panel-retaining strips may be placed upon one collecting panels or between adjacent collecting panels. The strips may press upon transverse surfaces of collecting panels to push and hold the panels onto flat or parabolic ribs to better assure that panels assume the desired shape. A transverse-retaining strip may span transversely from one end to the other end of the support assembly with its ends attached to the end rails or end cowlings.  FIG. 44  illustrates one example of using a retaining strip  4402  with a flattened end  4404  to secure the edge of a solar colleting panel  4410  beneath an end outer cowling  4406  with a screw  4408 . The screw  4408  may extend to a rib or a rib section enclosed within the outer cowling  4408  through an inner cowling (not shown) located therebetween, thereby attaching the outer cowling, the collecting panel  4410  and the inner cowling all together to a transverse rib or a rib section. In some variations as illustrated in  FIG. 44 , one side of the flattened end  4404  of a retaining bar  4402  that will rest against an end assembly  4412  will be trimmed flat to prevent an otherwise round edge from interfering with the end assembly  4412 . A finished solar energy collector with a plurality of transverse retaining bars may be seen in  FIG. 39 . 
     The transverse panel retaining strips may be “T” or “I” shaped, for instance, to allow the panels to engage the strips. Alternatively, the strips may have a hollow square or rectangular cross-section and lips that engage the tops of the panels to be secured to the support assembly. In some variations, the tension of the retaining strips may be adjusted to allow thermal expansion and/or contraction of the collecting panels. The retaining strips may be polished or mirrored to reflect light to a receiver if the support assembly is used to form a solar receiver, such as a parabolic-shaped solar energy collector described herein. Retaining strips need not be polished or mirrored, though, since little of the area that might otherwise be reflective is occupied by the retaining strips. 
     F. Guy-Wires 
     The support assembly may have optional guy-wires  901  as illustrated in  FIGS. 9A and 10  that may extend diagonally from one end assembly to the opposite end assembly of the support assembly. The guy-wires therefore cross in an “X”-shaped configuration. Alternatively, guy wires may run parallel to longitudinal rails to tie one end section or assembly to another. 
     The guy-wires help provide a rigid structure that resists torsion without adding significant weight to the support assembly or shading to the solar collecting panels. The guy-wires may be beneath solar collecting panels where the collecting panels are flat or substantially flat. Guy-wires may be used on the illuminated side of the energy conversion surface parallel to longitudinal rails or diagonal to the end longitudinal rails in generally an “X” shape for e.g., a parabolic or cylindrical trough collector to minimize mirror surface shading. The guy wires may be equipped with turnbuckles  902  that permit the wires to be tensioned a desired amount. 
     G. Mount Collar and Stand 
     A mount collar may be used to attach two end sections together and/or to engage the support assembly to a stand, which may contain a bearing to allow the support assembly to pivot along an axis defined by the bearing. In some variations, the mount collar may comprise a hole that permits passage of a collector tube and/or a mount tube. One variation of a mount collar is illustrated in  FIGS. 7 and 8A  to  8 C. The mount collar  702  in these figures comprises a base ring  810  and a neck tube  820  concentrically disposed on top of the ring  810 . The ring  810  and the neck tube  820  may have substantially the same inner diameter. The outer diameter of the base ring  810  is larger than the diameter of the cutout on the end assembly or the end section, through which the tube  820  of the mount collar extends through. The base ring  810  and the neck tube  820  are welded together at their interface in the variation shown in  FIG. 8B . In other variations, they may be attached to each other by other suitable attachment methods (e.g., by fasteners or by adhesive). The base ring  810  may be attached to the surface of the end assembly by rivets (e.g.,  840 ) or other suitable fasteners. 
     The neck tube  820  comprises holes  831  through which e.g., bolts or adjusting screws  830  extend (one of three adjusting screws is illustrated in  FIG. 7 ). The bolts or screws  830  may secure the mount collar  702  and a mount tube concentrically disposed within the mount collar, so that they rotate in unison. In some variations, the bolts or screws may extend through the holes to support a collector tube  850  that passes through a lumen defined by the mount collar  702  and the mount tube  850 , as discussed further below. In this variation, there are three adjusting screws  830  on the neck tube  820 . In other variations, there may be 1, 2, 3, 4, 5, 6, or more adjusting screws on the neck tube  820 . 
     A mount collar may be a separate piece that extends through an end assembly to join the end assembly to a stand. A mount collar may additionally help join end sections or end pieces to one another to provide a more rigid structure.  FIGS. 13-16  illustrate how a support assembly  100  is typically secured to stands  1301  and  1302  containing bearings  1402  to allow the support assembly  100  to pivot along an axis defined by the bearings  1402 . A stand  1302  may have a mount tube  1401  ( FIG. 14 ) extending through the bearing  1402  at either end or both ends of the bearing  1402  and extending into a mount collar  702  of the support assembly  100 . The bearings  1402  may be roller, ball, or graphite bearings that are retained by stand brackets  1403  that has a removable top to aid in assembly and maintenance. 
     In some variations, a mount collar may have two inner diameters if desired. Using  FIG. 15A  to illustrate this concept, a mount collar  702 ′ may have a first large inner diameter in a portion of the mount collar  702 ′ that will engage a portion of the bearing  1402 . The mount collar  702 ′ may also have a second smaller inner diameter in a portion of the mount collar that will engage the mount tube  1401 .  FIG. 15B  schematically illustrates the mount collar  702 ′ having two inner diameters. Alternatively, a mount collar may have a single inner diameter as is apparent from the structure  702  illustrated in  FIG. 15A , in which the mount collar  702  engages the mount tube  1401  but the mount collar  702  does not ride directly on the bearing  1402 . In a ganged structure that is discussed further below, both support assemblies of the mount collar may be secured to the same mount tube  1401 . 
     In the variation illustrated in  FIGS. 13 to 16 , the stands  1301  and  1302  comprise an elongate configuration. In other variations, the stands may comprise a triangular configuration (e.g., a right-angled triangle), as illustrated in  FIG. 39 . The hypotenuse  3910  of the stand  3900  may provide additional structural support compared to a stand only having the opposite  3912  but will not interfere with the rotation of the solar energy collector when the collector tracks the sun from east to west during operation. In some variations, a stand may comprise a motor compartment for a motor, which may be used to drive the rotation of one or more solar energy collectors. 
     A stand may be mounted to a concrete pad on which the support assembly is to sit. A stand may alternatively be mounted to a platform. Typically the support assembly&#39;s stands are mounted in a way that the support assembly is free to move only in rotation about a longitudinal axis of the support assembly. 
     H. Ganging 
     Support assemblies may be joined to one another longitudinally to form a ganged structure as depicted in  FIG. 17 . The resulting ganged support assembly may have two, three, four, five, six, or more support assemblies  100  as discussed above joined together so that the assemblies act in concert as one unitary assembly. 
     As shown in  FIG. 18 , support assemblies may be joined to one another by way of joints  1801 ,  1802  such as pipes with male or female coupling that attach to corresponding longitudinal rails of adjacent support assemblies, for instance. A joint will therefore attach to a longitudinal rail of one support assembly and a corresponding longitudinal rail of an adjacent support assembly. In other variations, two adjacent longitudinal rails may be joined by insertion of a joint with a surface protrusion (e.g., a key) to the longitudinal rails that may have a complementary recess (e.g., a key way). In still other variations, the joint may be welded to the connecting rails. 
     If only one joint is utilized, the ganged support assemblies may rotate at most 270 degrees before the joint will encounter a stand  1302 . Two or more joints provide a more rigid or reliable structure, so that adjacent undriven support assemblies move in concert with a single driven support assembly and therefore track the sun accurately. While the ganged support assemblies rotate at most 270 degrees, the amount that the ganged assembly may rotate may be at least 200 degrees, for instance, and may be at least 250 degrees or 260 degrees. 
     Alternatively, two or more support assemblies may be ganged to one another through mount collars, mount tubes and/or collector tubes. As illustrated in  FIG. 15A , a single mount tube  1401  may span two adjacent mount collars  702  and  702 ′, thereby ganging two adjacent support assemblies together. As shown in  FIG. 8C , a mount tube  850  may extend through a base ring  810  of one mount collar  702  and into the trough collector for a short length. Alternatively, this end of the mount tube  850  may be substantially aligned with the outer surface of the base ring  810 . In other variations, this end of the mount tube  850  may be disposed within the neck tube  820  of the mount collar  702 . Alternatively or additionally, two or more support assemblies may be joined to one another through the collector tube (e.g.,  1313  in  FIG. 15 ), which will be further discussed below. 
     I. Drive System 
     A support assembly or a linear array of support assemblies ganged together as discussed above may have a drive system positioned at one end as illustrated in  FIG. 17 . In this figure, the drive system comprise a large-diameter sprocket  1303  secured to the rotatable support assembly  100 , a motor  1304  having a small-diameter sprocket  2001  on a shaft  1320  of the motor  1304  and secured to a support stand  1301  or other structure that holds the motor so that the motor does not rotate with the support assembly  100 , a chain  2002  or belt engaging the small sprocket  2001  on the motor  1304  and the large sprocket  1303  on the support assembly  100 , and optionally one or more adjustable idler sprockets (not shown) along the length of the chain that tension the chain to remove slack. 
     The motor may have a gear reduction unit so that the shaft  1320  of the motor  1304  turns more slowly than the magnets of the motor rotate. In some variations, the gear reduction ration of the motor  1304  may be any of 50:1, 80:1, 100:1 or higher. The gear-reduction of the motor in conjunction with the gear-reduction provided by the gear ratio of the sprocket  1303  on the support assembly  100  and the sprocket  2001  on motor shaft  2001  provides accurate placement of the support assembly when tracking the sun. In some variations, the gear ratio of the sprocket on the support assembly and the sprocket on the motor shaft may be any of 5:1, 10:1, 20:1, 30:1, 40:1, 50:1, or higher. In some variations, the drive system may provide a torque output of about 20,000 inch-pound, or about 25,000 inch-pound, or about 30,000 inch-pound, or more. 
     The drive system may utilize a motor powered by DC current, so that the drive system may be reversible. The drive system may utilize a motor powered by AC current, in which case the support assembly may rotate 360 degrees if a support assembly is not ganged or if multiple support assemblies are ganged only through mount collars  702  and/or mount tube  1401  of  FIG. 14  but not joints  1801 ,  1802  of  FIG. 18 . Once tracking is completed for the day, the support assembly may be rotated in the tracking direction to invert the support assembly for the evening to protect the solar energy collecting surfaces, and in the morning the support assembly may be turned in the tracking direction to directly face the sun and track it. Alternatively, an AC motor may be equipped with a gear box that has a reverse gear in it so that the support assembly may be rotated in or against the tracking direction. The motors used to pivot or otherwise orient solar energy collectors may be controlled by tracking devices, which may determine the orientation of the sun and pivot the solar energy collectors to optimize the solar radiation collection. The tracking device may be, for example, conventional solar tracking devices known to one of ordinary skill in the art. Such tracking devices may employ, for example, data that correlates rotation of the collectors with time of day and season to control the motors. 
     As illustrated in  FIG. 17 , a row or a linear array of solar energy collectors  1700  may be rotated in concert by one drive system that comprises one motor  1304 , a drive shaft  1702  and one or more sprocket assembly that further comprises one large-diameter sprocket secured to the support assembly and one smaller-diameter sprocket secured on either the motor shaft  1320  or the drive shaft  1702 . The sprocket assembly may optionally comprise one or more adjustable idler sprockets. In some variations, only one motor is provided to drive an entire row of solar energy collectors. In such variations, the motor may be located at the end of the row or at any location along the row. In one variation, the motor is located at the middle point of a row and two drive shaft tubes may be coupled to the motor shaft and extend in opposite directions to drive the rotation of the entire row. In other variations, more than one motor may be used in each row to drive the concerted rotation of all collectors. 
     The drive shaft  1702  may be a single tube for the entire row  1700  of solar energy collectors or several pieces of tubes attached to one another.  FIG. 45  illustrates an attaching method to join two pieces of drive shaft  4506  and  4514  together. A drive shaft coupling  4500  may comprise a key shaft  4508  and a cylindrical drive shaft coupler  4510  with a complementary surface recess or groove configured to receive a base portion of the key shaft  4508 . When the key shaft  4508  is inserted into the drive shaft coupler  4510 , a top portion of the day shaft  4508  will protrude from the surface of the drive shaft coupler  4510  along the longitudinal length of the coupler  4510 . A drive shaft coupler  4602  without insertion of a key shaft is illustrated in  FIG. 46  The drive shaft may be solid to enhance the torquability of the drive system. The drive shaft tubes  4508  and  4514  may both have a complementary inner surface recess  4506  (e.g., a key way) configured to engage the surface protrusion (e.g., a key) of the drive shaft coupler  4510 . Two drive shaft tubes  4508  and  4514  then may be joined together with the drive shaft coupling  4500  by inserting the key  4512  of the drive shaft coupling  4500  into the key way (e.g.,  4506 ) of each drive shaft tube. The drive shaft  4514  may be locked in place with the drive shaft coupling  4500  by one or more bolts  4516  or screws circumferentially disposed on the drive shaft tubes. The other end of the drive shaft tube  4514  may be placed into a drive shaft bracket similar to the bracket  4502  in  FIG. 45  with a bearing. Another drive shaft coupling may be formed then to join the drive shaft tube  4514  with another piece of drive shaft tube. The drive shaft bracket  4502  may be mounted on the base  4501  of a drive stand  4503 . One or more spacers  4505  or washers may be used to adjust the height of the bracket  4502 . 
     In some variations, the row of linear array of solar energy collectors  1700  may comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more sprocket assemblies. As illustrated in one variation in  FIG. 39 , there is one sprocket assembly for every three solar energy collectors in a linear array of collectors  3920 . The number of sprocket assemblies used in a linear array of solar energy collectors may be selected in part based upon the dimensions, the weight of each collector, and/or the way how collectors are joined together. For example, in the variation shown in  FIG. 39 , three collectors may be joined to one another either through the joints between longitudinal rails or through mount collars and mount tubes. Alternatively, the entire row of collectors may be ganged together but intermittent sprocket assemblies may still disposed every three collectors to facilitate accurate placement of each collector when entire row is rotated tracing the sun. 
       FIGS. 47A to 47D  illustrate one large-diameter sprocket  4702  mounted on the mount collar  4704  of one solar energy collector  4700 . The sprocket  4702  may be placed flush to the mount collar  4704  and attached to the end assembly  4708  by one or more bolts  4710 . Spacers  4706  and arm hooks  4712  may be used in conjunction with bolts  4710  to secure and position the sprocket  4702 . 
       FIGS. 47A to 47D  only illustrate one exemplary method to mount the large-diameter sprocket to the solar energy collector. The large sprocket may be secured to the collector by any suitable attachment methods. In another variation as illustrated in  FIG. 13 , sprocket  1303  may comprise a ring  1323  with multiple arms  1322  symmetrically disposed within the ring  1323 . Arms  1322  are individually attached to the surface of end assembly or end section  1340  of the support assembly  100  by welding or fasteners, such as screws, rivets or bolts. In another variation as shown in  FIG. 19 , the sprocket  1303  comprises a solid wheel  1902 , which is attached to the end assembly or end sections  1906  of the support assembly by a plurality of rivets  1904  or other types of fasteners. 
       FIG. 46  illustrates one small-diameter sprocket  4604  mounted on a drive shaft tube  4606 . The small sprocket  4604  may sit on the end portion of the drive shaft tube  4606  that extends through a drive shaft bracket  4610  and may be secured to the drive shaft  4606  with one or more screws (only threaded holes  4808  shown in this figure). Screws may be adjusted to tighten the sprocket  4604  around the drive shaft  4606 . Further, the screws may be used to adjust the relative position of the small-diameter sprocket  4604  with respect to the large-diameter sprocket. Before tightening the screws of the sprocket  4604 , an installer may check the position of the small sprocket to ensure that it is plumb to the large-diameter sprocket located above. 
     In some variations, the sprocket assembly may optionally comprise one or more adjustable idler sprockets along the length of the chain to tension the chain and remove slack. The idler sprocket may be spring-loaded to bias the sprocket chain constantly in a tensioned state, therefore removing chain slack that may be caused by thermal expansion of the chain and/or other reasons.  FIG. 48  illustrates one variation of a mechanism to tension the sprocket chain. The chain tensioner assembly  4800  illustrated in  FIG. 48  comprises two arms  4803  and  4804 , two idler sprockets  4801  and  4802  and two springs  4805  and  4806 . Two arms  4803  and  4804 , with an idler sprocket  4801  and  4802  attached to one end of each arm and engaging a portion of the sprocket chain, are joined and pivotedly attached to a collector stand at the other end of each arm. Two loaded springs  4805  and  4806  with one end of each coupled to the collector stand  4808  bias the two arms  4803  and  4804  toward a close configuration to tension the sprocket chain  4810 , therefore removing chain slack due to thermal expansion. In some variations when the chain tensioner assembly is installed on the hypotenuse of a right-triangle collector stand, one arm (e.g.,  4804 ) may be longer than the other arm (e.g.,  4803 ) in order for the sprocket (e.g.,  4802 ) to engage the chain coming from a longer distance. In some variations, the chain tensioner assembly may be installed on the vertical side of a collector stand (e.g., right-triangle-shaped or elongate-shaped stand). In such variations, the two arms may or may not have the same length.  FIG. 20  illustrates another chain tensioner assembly that comprises one cross bar  2005  mounted on an elongate collector stand  1301  with two idler sprockets  2003  and  2004  attached to each end of the cross bar  2005 . Two sprockets  2003  and  2004  each engages a portion of the sprocket chain  2002  and biases the chain  2002  in a tensioned state. 
     J. Finishing Panels 
     The support assembly may have optional finishing panels (e.g., housing panels or cowlings) and end caps that cover the longitudinal rails and/or ribs and provide a covered appearance to the support assembly. Finishing panels may be made from metals, plastics (e.g., impact resisting plastics) or other suitable materials. Finishing panels may be coated with anti-corrosive materials and/or anti-rust materials to protect the support assembly. Finishing panels may be riveted, adhered, bolted, or otherwise secured to longitudinal rails, ribs, and/or end sections, or the finishing panels may be secured by longitudinal cross-bars. Finishing panels may also provide the support assembly with some structural rigidity by bearing loads into the finishing panels. 
       FIG. 9B  shows a cowling  903  secured by two pairs of longitudinal cross-bars  904 ,  1014 ,  1004 , and  905  covering an end longitudinal rail  930 .  FIG. 9A  shows the finished look of the cowling  903  completely covering the end longitudinal rail  930 . In other variations as illustrated in  FIG. 38 , an end cowling  3820  may be used to attach or affix solar collecting panel  3800  to the support assembly. In variations where an outer housing panel is placed on the outside of the support assembly, the edge of the housing panel may be also enclosed in the cowling  3820 . The cowling, the end longitudinal rail, the solar collecting panel, or the optional housing panel may be attached together by a plurality of rivets  3821  or other suitable attachment methods. In some variations as discussed before, an inner cowling may be used with the outer cowing  3820  to secure the solar panels and housing panels. 
     In  FIG. 10 , a portion of housing panel  1003  is viewed from a side of the support assembly that will support the solar energy collecting panels. Housing panel  1001  is retained at one end by longitudinal cross-bar  1002  and by a similar center longitudinal cross-bar  701  at the center or apex or minimum of the support assembly. In some variations one housing panel may span from one end longitudinal rail of the support assembly to the other. In other variations, a housing panel may span only from one end longitudinal rail to a center longitudinal rail located at the center or apex or minimum of the support assembly. Two opposite-facing housing panels may then be attached together through a longitudinal cross bar on the outside of the support assembly as discussed above. In other variations, two opposite-facing housing panels may be overlapped at the center or apex or minimum of the support assembly and the overlapped portions of two panels may be attached to one another by rivets, screws, bolts or welding. In some variations, one housing panel may extend the longitudinal length of the support assembly (e.g.,  1001  in  FIG. 28 ). In other variations, a housing panel may span only a portion of the longitudinal length of the support assembly and each support assembly may comprise a plurality of housing panels disposed side by side to cover the outside of the support assembly. 
     In some variations, cowlings  3830  may be used to cover the transverse rib or rib sections located at the end of a support assembly, as illustrated in  FIG. 38 . In some variations, end caps  2701  and  2702  of the support assembly of  FIG. 27  provide a finished look to the assembly. 
     The housing panels may be rigid so that they retain the desired installed shape during shipping. Alternatively, the housing panels may be formed of a material that is sufficiently flexible that the panels can be shipped flat or rolled up but curved into shape on-site where the trough collectors are being installed for use. Optionally, the flexible material can also be sufficiently rigid that the material can lock ribs or rib sections in place longitudinally. In one variation, the housing panel may be made (e.g., cut or stamped) from aluminum sheets having a thickness of about 1 mm to about 2 mm. Any other suitable materials with suitable thicknesses may also be used. Suitable materials included, but are not limited to, metals, metal alloys (e.g., sheet steel or galvanized steel), plastics including impact resistant plastics, and wood. 
     K. Solar Energy Collecting Panels 
     Referring to  FIG. 13 , the illustrated trough solar energy collector  1300  has a support assembly  100  supporting parabolically shaped solar energy collecting panels  1306 ,  1307 ,  1308 , and  1309 . Each collecting panels shown in  FIG. 13  spans transversely from one end longitudinal rail to the other and spans longitudinally about one-fourth longitudinal length of the support assembly  100 . Alternatively, each collecting panel  1306 - 1309  may comprise two identical pieces that are joined to one another at the center, vertex, or minimum point of the support assembly  100 . The two panel pieces may be joined by a joining member. For example, two panel pieces may both be attached or affixed to the center cross-bar at the center, vertex, or minimum point of the support assembly.  FIG. 10  illustrates one collecting panel piece  1040  being secured by the center cross-bar  701 . Alternatively, two panel pieces may be attached to one another by welding, rivets, screws, bolts or other suitable fasteners. One or more collecting panel or panel pieces may be disposed side by side along the longitudinal length of the support assembly. In some variations, the support assembly may be used to support any number, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more of collecting panels or panel pieces form a solar energy collector. 
     Collecting panels or panel pieces supported on a support assembly may comprise a substantially parabolic shape with a line focus approximately on a central axis of a heat collector, which will be further discussed below. In other variations, collecting panels or panel pieces in the solar energy collector may comprise a substantially cylindrical (partial circular cross section) or any other suitable shapes. Collecting panels or panel pieces may be made from an elastically deformable material that allows them to assume a flat shape absent deforming forces but take a parabolic or other curved shape upon placement on the support assembly. In some variations, solar energy collecting panels are elastically deformable minors, which may be made, for example, from highly reflective aluminum sheets such as coated (weather-proofed) highly reflective aluminum sheets available under the product name MIRO-SUN® and manufactured by ALANOD Aluminium-Veredlung GmbH &amp; Co. KG of Ennepetal, Germany. In other variations, elastically deformable panels may be made from other materials such as, for example, reflectively coated plastics and other reflective or reflectively coated metals. In some variations, elastically deformable materials may comprise a reflective film such as, for example, a reflective or reflectively coated polyethylene terephthalate (e.g., Mylar®) film supported by an elastically deformable substrate such as, for example, a plastic or an unpolished aluminum sheet or panel. 
     Collecting panels or panel pieces may be secured to the support assembly by any suitable attachment methods in order to assume the parabolic or otherwise curved shape as the support assembly. As previously discussed, various structures and methods, including but not limited to end cowlings (e.g., inner and outer cowlings), transverse retaining strips, and/or longitudinal cross-bars, may be used to secure and hold the solar energy collecting panels to the support assembly. 
     L. Longitudinal Collector Tube 
     A longitudinal collector tube  1313  of  FIG. 13  or  1602  of  FIG. 16  may be positioned approximately coincidentally with the line of focus of parabolic collecting panels to receive light reflected by the collecting panels of a solar energy collector. In some embodiments, the collector tube may be made from black iron, carbon steel, 304 and 316 stainless steel, copper, aluminum, or any other suitable metals or metal alloys. The collector tube may be coated with a coating (e.g., paint) on its inner surface and/or outer surface to enhance its thermal performance, e.g., to promote absorption of solar incident radiation and/or to minimize thermal loss from the collector tube. Some examples of the coating materials include, but not limited to, black paint, black chrome, a three-layer coating comprised of metallic titanium, titanium oxide, and antireflection coating, aluminum nitride, black-colored CuCoMnO x  formed using sol-gel synthesis, C/Al 2 O 3 /Al, or Ni/Al 2 O 3 . 
     The collector tube may have a working fluid running through it. The working fluid may be an organic liquid whose boiling point is greater than the temperature typically encountered in a solar trough collector, such as an oil. The working fluid may also be an organic liquid that undergoes boiling in the tube to produce vapor, such as Freon or methylene chloride. The collector may instead have a liquid or a liquid/gas mixture, lithium bromide, glycol, ammonia, water and/or steam passing through the collector tube. The working fluid may or may not undergo a phase change. In some variations, the working fluid may reach temperature from, for example, about 100° F. to about 550° F., sometimes about 150° F. to about 500° F., sometimes about 200° F. to about 450° F., and other times about 250° F. to about 400° F. 
     The collector tube may traverse the length of the solar energy collector. The tube may or may not connect to a joint that may be rifled or dimpled to create turbulent flow. Alternatively, collector tube may pass through a mount collar and mount tube  1401  of  FIG. 16  that joins to stands  1302 , which support the solar collector and its support assembly. A single collector tube  1602  may be used for ganged support assemblies, or the collector tube may be formed in sections so that several adjacent support assemblies share a single collector tube. Alternatively, each support assembly may have its own collector tube that joins to adjacent collector tubes through joints, hoses, or other types of connectors typically used in joining pipes that undergo frequent thermal expansion and contraction. In some variations, adjacent collector tubes are welded together. 
     A support assembly may have one or more stanchions to support the collector tube. In some variations, one or more two-leg stanchions  2201  of  FIG. 22  and/or single-leg stanchions  2301 ,  2302  of  FIG. 23  are positioned between the transverse end assemblies and may attach to ribs, transverse panel-retaining strips  1310 ,  1311 , and/or optional longitudinal cross-bar  701 . In other variations, a stanchion may attach to one or more longitudinal rails, especially the rail or rails located at the center, apex, or minimum of the support assembly. A stanchion may have adjustment screws or bolts  2202  of  FIG. 22  that can be adjusted to provide better focus on the collector across the length of the collector assembly. Collecting panels may be not perfectly flat when installed due to normal manufacturing tolerances. The adjustment screws or bolts allow portions of the collector to be repositioned somewhat to better illuminate the collector, increasing collection efficiency. 
     The collector tube may be rigidly secured to the solar energy collector via adjusting screws and/or bolts extending from the mount collar and stanchion, so that the collector tube rotates in unison with the solar energy collector. A collector tube may join a pipe that is held stationary on e.g., a pipe rack through a “swivel” joint that allows rotation of one end of a collector, or the collector tube may join a pipe through e.g., a braided hose. 
     Alternatively, the collector tube may be stationary. It may be held in a bearing such as a ball, needle, or graphite bearing that permits the solar energy collector to support the weight of the collector tube and fluid passing through it while allowing the solar energy collector to rotate while the collector tube remains stationary. 
       FIGS. 29 and 30  illustrate one variation of a stanchion assembly  2900  that supports a stationary collector tube  2906 . The stanchion assembly of  FIG. 29  has a ring  2901  (in this instance, a split ring, although a split ring is only optional). Set screws  2902  push on a tube  2904  around a bearing  2905  such as a graphite bearing. The receiver tube  2906  engages the inner surface of the bearing  2905 . The stanchion  2900  rotates in conjunction with the solar energy collector to which the stanchion is mounted. The bearing  2905  likewise rotates in conjunction with the solar energy collector and rotates about the stationary collector tube  2906 . In some instances, the bearing  2905  and the tube  2904  surrounding the bearing  2905  may be splittable. A split ring  2905  and a split metal tube permit a split bearing to be replaced without having to disassemble an end of the solar energy collector, easing maintenance on the solar energy collector. 
     In some variations, the tube  2904  may be an independent structure, which is configured to bear the weight of the solar collector. In other embodiments, the tube  2904  may be attached to the mount tube or may be a portion of the mount tube that is extended through the mount collar.  FIGS. 31A and 31B  show a mount collar  3101  which may be configured similarly to the stanchion assembly to have set screws  3102  push on mount tube  3103  around a bearing  3107  such as a graphite bearing. The inner surface of the mount tube  3103  engages a collector tube  3106 . A split ring  3104  retaining the bearing  3107  allows easy replacement of the bearing, especially if the bearing and the tube  3103  around the bearing  3107  area also split. In one instance, the collector tube  3106  may extend through the mount collar  3101  and engages the stand of the support assembly. As a result, the stationary collector tube will support the weight of the solar collector. Alternatively, mount tube  3103  may engage the bearing in a stand as described previously. The bearing retained by the stand and engaging the mount tube of the mount collar  3101  supports the weight of the solar energy collector, and the bearing  3107  within the mount collar  3101  and engaging the collector tube permits the collector tube  3106  to remain stationary as the solar energy collector is rotated to track the sun. 
     Set screws in the stanchion assemblies and the mount collars move their respective bearings in y and/or z directions. The collector tube may therefore be adjusted relative to the collecting panels to better align the collector tube along the focal line(s) or focal surface(s) of the solar energy collecting panels, improving collection efficiency. 
     In some variations, at least a portion of the collector tube may be surrounded or enclosed by one or more tubular sleeves. In such variations, the rings of the mount collars and/or stanchions may be sufficiently large to engage the sleeves.  FIG. 32  illustrates one variation of transparent collector tube sleeves  3201  and  3202  disposed around a collector tube  3203  of a solar energy collector  3200 . A sleeve may help insulate the collector tube to reduce loss of heat from the tube to the surrounding cooler atmosphere by conduction and/or convection. The collector tube sleeve may be made from glass (e.g., Pyrex or borosilicate glass) or suitable polymeric materials (e.g., polymethylmethacrylate, butyrate, or polycarbonate). In some variations, a single sleeve may extend the length of the collector tube along a trough solar energy collector. Alternatively, multiple sleeves may be used to cover parts or all of the length of the collector tube, as illustrated in  FIG. 32 . The solar energy collector  3200  illustrated in  FIG. 32  has two sleeves  3201  and  3202  that extend along a portion of the length of the collector tube  3203 . The sleeve or sleeves may cover at least about ½, at least about ⅔, at least about ¾, or all of the exposed collector tube in the vicinity of the collecting panels  3205 . In some variations, the space between sleeves and the collector tube may be evacuated. Alternatively, the space between the sleeves and collector tube may be filled with a gas. The gas may be air or an inert gas under pressure to preventingress of dirt and moisture. 
     The collector tube sleeve may or may not be transparent. The sleeve may be coated with a coating material that may enhance solar radiation adsorption. In some variations, the collector tube sleeve may have one or more holes that permit condensate to drain when the solar energy collector is placed in a parked position where collecting panels are not tracing the sun. 
     In one instance, the sleeve is formed of a flexible material (e.g., polymers) that has a slit running along the longitudinal length of the sleeve. The sleeve material may be sufficiently flexible in one or more locations along the sleeve that the slit opens when the sleeve wall adjacent to the slit is pushed or squeezed. An inventor or installer  3204  may temporarily move or deform the wall of the sleeve in the vicinity of the slit at one end of the sleeve such that the slit opens to admit the collector tube. The installer then works from that end of the sleeve to the other end, squeezing adjacent areas of the sleeve to admit the collector tube to place more and more of the sleeve over the collector tube until finally the sleeve is placed entirely over the collector tube. The slit may be covered with a seal such as a silicone gasket. The seal may be removable or may be permanent. In one instance, the seal has a portion that inserts into the narrow slit and a gripping portion that conforms to the surface of the sleeve. The sleeve may be removed from the collector tube in a similar fashion. 
     End plugs may be placed over the collector tube to engage the ends of the sleeve to close the ends and retain much if not all of the heated air within the sleeves when the solar energy collector is placed in service. The end plugs may be polymeric or metallic, for instance. The end plugs may engage the outer wall of the sleeve. Alternatively, end plugs may engage the inner wall of the sleeve. End plugs may be flat or may be tapered, for instance, so that the plugs may be driven into the ends of a sleeve and hold it away from the surface of the collector tube. An adhesive may be used to secure end plugs to the sleeve. In some instances, a flexible polymer such as a silicone polymer may be placed between the sleeve and end plugs to seal and retain the sleeve to end plugs. The slit may be sealed using e.g., adhesive or transparent polymeric tape if desired. 
     In other variations, the collector tube sleeve may be formed of a semi-flexible or rigid material (e.g., glass) that has a slot running along the longitudinal length of the sleeve. A collector tube sleeve having a slot may be formed many ways. The sleeve may be cut longitudinally using e.g., a diamond-tipped saw to slice a very thin channel perpendicular to the wall of an uncut tube. Alternatively, a circular or band-saw can be used to slice an arc from a tube along the length of the tube. A tube cut in this manner is illustrated in  FIG. 37 , in which the slotted sleeve  3701  is illustrated along-side the arc-shaped piece  3702  that was removed from a tube used to form the sleeve. Edges of the cut sleeve may be polished to avoid injuring the installer  3204  as well as to avoid snagging a movable cover that will be discussed in greater detail below. 
     In some variations, the collector tube sleeve may comprise a cover configured to cover or seal a complementary slot on the collector sleeve. The cover may engage the slot, thereby encapsulating the collector tube if ends of the sleeve are also secured and sealed to the collector tube as discussed above. A cover may fit within or upon the slot on the collector sleeve. The cover may be flat or may be curved. A curved cover may have a circular or parabolic arcuate profile, for instance. The cover may have the same curvature as the collector tube sleeve, or the cover may have a different curvature. For instance, the cover may be parabolic while the tube sleeve is generally circular in profile. If the cover is reflective and arcuate, the curvature of the arc (e.g. circular arc or parabolic arc) is preferably one that focuses solar energy upon the collector tube when the cover is seated upon the collector sleeve. 
     A cover may be formed of any suitable material. Considerations in selecting a material from which to form a cover include (a) whether the cover itself will transmit light, in which case the material would be transparent to the desired light wavelengths; (b) whether the cover is to be reflective; (c) the operating temperature range and/or peak temperatures that the cover will encounter; (d) how well the material of the cover seats onto the thermal solar energy collector tube; (e) weight, rigidity, and/or strength of the cover material; and any other considerations appropriate to use. In some variations, the cover may be made from a metal, such as aluminum (polished or unpolished) and stainless steel with high rigidity. The inner surface of a metal cover may optionally be silvered to make a reflective surface. In other variations, the cover may be made from a thermally insulating material such as a polymer (e.g., a rigid polymer such as a polycarbonate, polyamide, or polyimide). The inner surface of a polymeric cover may also have a mirrored coating to reflect light. The outer surface of a cover may be coated with an anti-reflective coating to enhance solar radiation transmittance through the cover. 
     In some embodiments, a reflector may be placed between the cover and the collector tube. Such a reflector may catch any solar radiation reflected by collecting panels but missed by the collector tube and reflect back to the heat collector. In some variations, the reflector may be an elongate flat or curved strip covering the majority of the longitudinal length of the collector tube and be placed underneath the cover. In other variations, the reflector may be shorter strips placed only at multiple desired locations along the longitudinal length of the collector tube. The reflector may or may not be made from a same material as the cover. In one example, the reflector may be a polished aluminum strip having about the same longitudinal length as the cover. 
     In some variations, the cover may be fixedly mounted on the collector tube sleeve by any suitable attachment methods, such as riveting, bolting and screwing. In other variations, the cover may be movable. The movable cover may engage and seal the slot on the collector sleeve as the solar energy collector tracks the sun through the day. However, the cover may disengage from the slot on the collector sleeve when the solar energy collector is parked in the evening, preventing condensate from forming within the sleeve or draining any condensate formed. The movable cover also enables water or air jets that may be mounted beneath the parked solar energy collector to shoot jets of fluid into the sleeve to clear the sleeve of dust and/or debris that has collected within the sleeve. 
     The movable cover may be attached to a track or rail, which is configured to move in concert with the collector sleeve. When the solar energy collector is tracking the sun and collecting solar energy during the day, the movable cover is placed upon the slot of the collector sleeve, thereby rotating with the collector sleeve. As a result, there is no relative motion between the movable cover and the cover track. When the solar energy collector is rotating towards its parked position and beyond a certain point, the movable cover will be removed from the collector sleeve. In some variations, the movable cover will be lifted from the sleeve slot by a disengaging mechanism. The movable cover may travel along the cover track for a distance, thereby uncovering the slot on the collector sleeve. When the solar energy collector rotates away from its parked position on the following day, the movable cover will be placed back upon the sleeve slot by an engaging mechanism. 
     The cover track may be disposed at one or both ends of the collector tube. In some variations, one or more tracks may be optionally disposed at one or more locations along the longitudinal length of the collector tube. The movable cover, the cover track, and the engaging and/or disengaging mechanism may optionally be attached to the collector sleeve, thereby rotating together with the sleeve when the solar energy collector tracks the sun. 
     One variation of a track assembly comprising a cover track with cover engaging and disengaging mechanisms is schematically illustrated in  FIGS. 35A to 35C , which are cross-sectional views of a movable cover at different positions as the solar energy collector is rotated.  FIG. 35A  depicts the collector tube  3303  and the movable cover  3301  of a solar energy collector at noon. At the depicted position, collector tube  3303  is enclosed by slotted sleeve  3302  and movable cover  3301 , which engages the cover track  3305  with a partially compressed spring  3308 , which is disposed between one end of the movable cover  3301  and a stop  3309  fixed to the cover rack  3305 . A finger  3306  or any type of protruding structure on the movable cover  3301  rests against an edge  3307  of the collector tube sleeve  3302  and stops the movable seal  3301  from moving due to the compressed spring  3308  acting on the movable seal  3301  and stop  3309 . The distance between the stop  3309  and the movable cover  3301  may be selected in part upon the type, the length and the configuration of the spring  3308  in order to resist relative motion between the cover  3301  and the cover track  3305 . 
       FIG. 35B  illustrates how a tab  3310  or any other suitable protruding structure on the stationary collector tube  3303  has engaged finger  3306  of the movable seal  3301  as the collector rotates clockwise toward its parked position. The finger  3306  prevents the cover  3301  from moving with the rotating sleeve  3302 , rail  3305 , and stop  3309 . Spring  3308  has been further compressed as the solar energy collector moves toward its parked position, partially revealing the open slot on the sleeve  3302 . 
       FIG. 35C  shows the positions of the sleeve  3302 , spring  3308 , movable cover  3301 , and collector tube  3303  when the solar energy collector is parked. Comparing to the position illustrated in  FIG. 35B , the cover track  3305  has rotated further and has further compressed the spring  3308  while movable cover  3301  was retained in place by tab  3310  and finger  3306 . Slot  3311  of the sleeve is entirely exposed. Water or air jets, for instance, can now enter the space between the sleeve  3302  and collector tube  3303 , cleaning the outer surface of the collector tube  3303  and the inner surface of the sleeve  3302 . 
     When the solar energy collector rotates counter-clockwise to an operational position (e.g., the position illustrated in  FIG. 35A ), the sleeve  3302  and cover track  3305  move back through a position as depicted in  FIG. 35B . The compressed spring  3308  continues to push the finger  3306  of movable cover  3301  against tab  3310  attached to the stationary collector tube  3302 , partially covering the slot  3311 . As the solar energy collector continues to rotate counter-clockwise, the sleeve  3303  and cover track  3305  continue to move until finger  3306  presses against edge  3307  of the sleeve  3302  and the slot on the sleeve  3302  is fully closed by the movable cover  3301 . The cover  3301  remains in this closed position as the solar energy collector rotates through the noon position depicted in  FIG. 35A  and to its operating position to start the day&#39;s operation. 
     The cover track  3305  may not be a circular track. The track may have more of an ellipsoidal shape or other shape having a minimum position placed to help unseat the cover  3301  from or seat the cover  3301  onto the sleeve  3302 . As the solar energy collector rotates from an operational position and toward its parked position, the eccentrically-shaped rotating track  3305  can lift the cover away from the sleeve  3302  as the sleeve  3302  rotates past the cover  3301 , which is held stationary by the tab  3310  on stationary collector tube  3303 . Likewise, the eccentrically-shaped track helps seat the cover  3301  onto the sleeve  3302  as the track  3305  and sleeve  3302  rotate back to their operational position. 
       FIGS. 33 and 34  illustrate the variation from  FIGS. 35A to 35C  as the track assembly installed on a solar energy collector. As illustrated in these figures, a slotted collector tube sleeve  3303  with a movable cover  3301  is placed between two track assemblies  3400 . The movable cover  3305  may be attached to the track assembly  3400  by a bracket  3310 , which is in slide contact with the cover track  3305 . The bracket  3310  may be made of the same material (e.g., polymer) as the movable cover  3301 . The bracket  3310  may be made from a metal or metal alloy in some variations. The movable cover  3301  may be attached to the bracket  3310  by welding, rivets, screws, bolts or any suitable attachment methods. The slotted sleeve  3302  and the complementary cover  3301  may span the entire length of the collector tube  3303  or only a portion of the length of the collector tube  3303 . The track assembly may be attached to a mount tube  3320  (as illustrated in  FIG. 33 ) in order to rotate with the solar energy collector when it tracks the sun. In other variations, the track assembly  3400  may attached to the tube (e.g.,  2904  in  FIG. 29 ) in a stanchion assembly. The track assembly that comprises the cover track  3305 , the engaging mechanism (e.g., the spring  2604 ) and/or the disengaging mechanism (e.g., the complementary finger  3306  on the cover and the tab  3310  on the collector tube  3303 ) illustrated in  FIGS. 35A to 35C  is only exemplary. Any other suitable means or mechanisms may be employed to engage or disengage the movable cover. For example, both movable cover and the collector tube may comprise magnets to facilitate their engagement. In some variations, the polarity of either or both magnets may be altered as the solar energy collector rotates. 
       FIG. 36  illustrates another variation of a track assembly located near a stanchion  3601  or alternatively near a mount collar. A sleeve  3612  enclosing a collector tube  3602  may be retained within the split ring  3603  by a plug or seal  3640 . In some variations, the seal or plug may be a silicone seal positioned between the outer wall of the collector tube  3602  and the inner surface of the sleeve  3612 . The track assembly  3600  has a mounting bracket  3605  that attaches to the stanchion  3630 . A bracket  3606  has holes  3607  and  3608  that allow a track  3609  to continue rotating yet retain the bracket  3606  and cover  3610  in a generally arc-shaped path. The bracket  3606  is attached to the movable cover  3610  by a single screw  3611  in a manner that permits the cover to flex and perhaps wiggle into a seated position on the slotted sleeve  3612 . 
     The mechanism described above to control the motion of the sleeve cover is only one variation. In other variations, the cover may be lifted, slid or otherwise removed by a cam, a lever, or any suitable structures. Further, instead of having a slot along its longitudinal length, the collector sleeve may, in some variations, comprise more than one opening, deposed on the sleeve either circumferentially or longitudinally. In variations where the sleeve comprises a plurality of openings, the movable cover may be sufficiently large to cover all openings. Alternatively, there may be a plurality of covers that cover corresponding openings. In still some variations, the solar energy collector may comprise more than one collector tube. An array of collector tubes may be placed approximately coincident with the line focus of parabolic collecting panels. Variations of collector tubes are described in detail in U.S. Provisional Patent Application Ser. No. 61/081,655, filed Jul. 17, 2008, titled “Thermal Energy Receiver,” which is incorporated herein by reference in its entirety. 
     The heated working fluid in the collector tube may be used directly to supply heat for an application or, for example, as a working fluid used to drive a turbine for power generation. The turbine may be a steam or organic Rankine engine and turbine, for example and/or for process heat. Alternatively, the working fluid may function as a heat transfer fluid that transfers heat collected in solar energy collector to another working fluid which is subsequently used in an application. In another variation, the working fluid may pass to an absorption chiller or other form of chiller to provide chilled air for air conditioning, for instance. 
     Described above are various support assemblies and solar energy collection systems. Table 1 provides a summary of different combinations of features that may be present in different support structures and/or solar energy collection systems. The combinations outlined in Table 1 apply for support assemblies and solar energy collection systems in which the number of longitudinal rails and/or their location differs from the number and location specified in the table. Consequently, the same combinations of features specified in Table 1 apply to structures and systems in which there are: (a) two longitudinal rails, (i) one at each end of the ribs of the support assembly; (ii) one at an end and one at a center, vertex, or minimum of the support assembly; or (iii) both rails are at the center, vertex, or minimum of the support assembly; (b) three longitudinal rails, (i) one at the center and two at the ends of the ribs; (ii) one at the center and two between respective ends and the center; or (iii) two or more at the center of the assembly; (c) four longitudinal rails, (i) two at ends and two at the center; (ii) two at the center and two between respective ends and the center; or (iii) at least one at the center; (d) five longitudinal rails, (i) two at ends, one at the center, and two between respective ends and the center; (ii) two at the center, two at ends, and one between an end and the center; or (iii) at least two at the center; (e) six longitudinal rails, two at ends, two at the center, and two between respective ends and the center; and (f) eight longitudinal rails, two at ends, two at the center, and two each intermediate between respective ends and the center. Other combinations and numbers of rails are of course possible, and a support structure may have more than eight rails. Table 1 is therefore to be read as applying to each of the combinations of two, three, four, five, six, and eight rails discussed above as well as to support assemblies and other structures that incorporate e.g. seven or more rails. 
     For example, the support assembly  100  illustrated in  FIG. 1  may be one exemplary embodiment of entry  64  of Table 1, where parabolic rib sections (e.g., half parabolic) and double-piece “Y”-shaped end assemblies are used in conjunction with a plurality of longitudinal rails. 
     Support assemblies and other pieces used to form solar energy collection systems, which have been described above in great detail, may be provided in unassembled form. Rib sections, transverse end sections, solar energy collecting panels, and/or housing panels or cladding may all be shipped as flat pieces that stack easily. Likewise longitudinal cross-bars and longitudinal rails may be bundled and shipped, or these pieces may be obtained locally to simplify shipping. Pieces may be placed on a pallet or in various boxes as may fit conveniently within containers in order to ship the pieces. Hardware such as spacers, fasteners such as rivets, bolts, nuts, and adhesive, guy wire, turnbuckles, and other pieces may be packaged and included in boxes for shipment. 
     Drawings of the various pieces described throughout this specification may be supplied by drafts-people who have manually drawn the various pieces, or the drawings may be formed and stored in a computer. 
     It is to be understood that any of the additional pieces discussed above, such as the longitudinal cross bars, guy wires, turnbuckles, stands, solar energy collecting panels, drive assembly, ganging pieces, finishing panels, cowlings, longitudinal collector tube, and hardware may be provided with any combination specified in Table 1 and text explaining Table 1. Further, any combination of the pieces listed in this paragraph may be combined with any of the combinations specified in Table 1 and text explaining Table 1. For example, the entry  64  of Table 1 (e.g., the support assembly  100  in  FIG. 1 ) may or may not comprise a longitudinal cross-bar (the exemplary embodiment shown in  FIG. 1  comprises a longitudinal bar). As another example, one support assembly shown in  FIG. 9A  illustrates a combination of entry  13  of Table 1 (full parabolic rib with double-piece “Y”-shaped end assemblies) and a bundle of additional features (e.g., guy-wires  901 , longitudinal cross-bars  701 , cowling  903  and housing panels). 
     II. Wash 
     The solar energy collection system may have a wash mechanism which will provide for a water or compressed air cleaning. For example, a sprinkler system may be mounted beneath the solar energy collectors such that when the solar energy collector is in its parked position, water, air or other suitable washing fluids may be sprayed onto the collecting panels, collector tube or into the collector tube sleeve when the collector tube sleeve is removed to remove contaminants accumulated on these parts. The sprinkler system may be controlled by the tracking device such that once the solar energy collector rotates to its parked position and the sleeve cover is removed to expose the collector tube, the sprinkler system may be activated to spray washing fluid. In other variations, the sprinkler system may be controlled by a separate control system. In some variations, the covers for the slotted sleeve may be removed manually for cleaning. 
     In some variations, an automated solar collector wash mechanism may be used to clean one trough collector or a row of trough collectors.  FIG. 56  illustrates one variation of the automated wash mechanism  5600 , which comprises a pressure source  5602  configured to pump or otherwise drive water or other suitable cleaning fluid from a water source  5206  to the cleaning site  5606  (e.g., a solar field). The water source may be a water storage unit such as a tank, a water main or a natural water source (e.g., a lake). Before water reaches the cleaning site  5606 , it may be mixed with cleaning detergent or other additives as desired. Such process may occur before or after water enters the pressure source  5602 , which may be a pump. The automated wash mechanism  5600  may further comprise a piping system  5610  having a layout of pipes and nozzles in a solar field, and a control mechanism  5608  configured to control the cleaning process of one or more trough collectors of interest. Pipes of any suitable size and material may be used to transport water from the water source to the solar collectors to be cleaned. In the specific variation in  FIG. 56 , 4″-diameter high density polyethylene pipe is used as main feed introducing water from a water storage tank  5604  through a water pump  5602 . 3″-diameter pipes may be optionally used to connect the main feed and run along the solar energy collector rows. When the piping system reaches the collectors farther away from the main feed, even smaller diameter pipe, e.g., 2″-diameter, may be used to ensure that nozzles for end-of-row collectors receive adequate pressure and amount of cleaning fluids. Any suitable connectors, such as compression fittings or saddles, may be used to connect pipes with different diameters. The pipes that run through the solar field may be equipped with nozzles for water ejecting. The spacing between nozzles may be selected depending in part on the collector size, the water pressure, and the nozzle size. In one example, a collector having about 12 feet longitudinal length may be washed by two 4-feet-apart nozzles, placed about one-third and two-thirds of the longitudinal length of the collector. In some variations, the nozzles may be used in pairs along the longitudinal length of a collector row. In some variations, the nozzle may be placed facing upward such that the water flow exiting the nozzle is substantially perpendicular to the ground. In other variations, the angle between the nozzle and the ground is different from 90 degrees. In still other variations, the nozzle orientation may be controlled by the control mechanism that will be discussed in further detail later. In some instances, one nozzle of the nozzle pair may be configured to wash the collector tube and the other of the pair may be configured to wash the solar energy collecting panels. In this variation, two nozzles may form different angles with respect to the ground from each other. 
     A control mechanism that comprises one or more solenoid valves may be used to control the cleaning process. In the variation illustrated in  FIG. 56A , each collector row comprises one solenoid valve  5622 . In such a set-up, each row of the solar field may be washed independently. To allow the solar field to be washed in segments may be particularly beneficial when the water supply is limited. Segmented washing scheme may also be beneficial when certain rows of collectors are more likely to be exposed to contaminants than others. For example, one row on the side of the solar field may be more exposed to contaminants then the inner rows. As another example, the wind may blow in a certain direction so that one row may block the other rows from the contaminants.  FIG. 56  B illustrates another variation of the piping system and control mechanism with more than one solenoid valves in each collector row. Additional solenoid valves may be added to enhance the specificity and degree of control. As shown in this figure, each row of solar energy collector comprises three solenoid valves, which are located at both ends and the middle of the row. These additional controllable valves allow more flexibility in terms of regulating washing scheme. For example, the second half  5630  of each row now can be separately washed with the valve  5620  opened and valves  5622  closed. The change in the valve setup may result in change in the piping system. For example, when the second half  5630  of the row is separately washed, because of reduced length of the working pipe, the pressure level of the washing fluid (e.g., water) may be increased for a higher pressure wash. 
     The solenoid valves may be controlled by a control center using e.g., a time-based main controller, which may open and close the valves individually, thereby enhancing consistency in the washing scheme. In some variations, the main controller for the automated washing mechanism may be independent from the control mechanism for the tracking system and/or CSP (concentrating solar power) plant information (e.g., thermal loop information, heat generation, etc.). In other variations, the control mechanism for the washing mechanism may at least partially share certain input information with other control mechanisms. For example, the main controller for the solenoid valves may use an input from a solar tracking system regarding the position (e.g., light-collecting position or a parked position) of solar energy collectors to determine whether a washing session should begin. As another example, the control system for washing may acquire thermal input from CSP plant to determine whether a collector is in its working mode. Various embodiments of control mechanism used for tracking system have been described in great detail in U.S. Provisional Patent Application Ser. No. 61/135,146, filed on Jul. 16, 2008, titled “SopoTracker”, which is incorporated herein by reference in its entirety. 
     It is noted that the layout of the piping system and the valve setup illustrated in  FIGS. 56A and 56B  are only exemplary. The use of solenoid valve is not necessary either. Other types of controllable valves may be used. 
     III. Photovoltaic Panels 
     One or more photovoltaic panels may be secured to a support assembly. The ribs of the support assembly may be flat in this instance, or the ribs may be angled to allow photovoltaic panels on adjacent halves or quarters of the support assembly to angle somewhat to e.g., reflect a portion of light to panels on opposite halves or quarters of the support assembly. Light that would otherwise be reflected may therefore be captured by panels mounted on an opposite portion of the support assembly. 
     Support assemblies may be joined to one another to provide a ganged support assembly, as discussed previously, and photovoltaic panels may be secured to the support assemblies by any suitable attachment methods. 
     The support assembly may be used to support solar energy collection panels, such as mirror panels for a solar reflector. The reflector may be configured as a trough solar collector, in which the solar energy collector rotates with the support assembly, or the reflector may be configured to operate as part of a Fresnel solar array. The support assembly may also be used to position photovoltaic cells to track the sun and maximize efficiency. Further, the support assembly may also be used to position an array of tubes or pipes that absorb solar energy directly to e.g. produce hot water. 
     IV. Method of Assembling One or More Solar Energy Collectors 
     In some variations, solar energy collectors may individually have e.g., three or four solar energy collecting panels adjacent one another in a collector and have a length of e.g., about 9-12 feet respectively. Multiple solar energy collectors may be are assembled into a row of collectors. 
     A row of trough collectors may contain any number of trough collectors, for example, 2, 3, 4, 5, 10, 15, or more. The collectors in one row pivot on bearings supported by stands between ganged collectors. One, two or more drive motors may be used to pivot the collectors to track the sun. Each collector may comprise one sprocket assembly. In other variations, two, three, four or more collectors share one sprocket assembly. In some variations, a plurality of collectors are first assembled into collector sections comprising, for example, two, three, four or more collectors, and sections may then be assembled into a row. 
     A method for assembling solar energy collectors to form a row may include the following steps, though in some variations some steps may be performed in a different order, may be performed concurrently, or may be omitted. Assembly methods in some variations may include additional steps as well. The steps to assemble a row of trough solar energy collectors  3920  as illustrated in  FIG. 39  are described below. 
     A. Formation of Transverse End Assemblies 
     In one instance, one end section is formed by riveting two end plates with cowlings and spacers. Two end sections are interdigitated and placed upon a mount collar and a mount tube to form one transverse end assembly (as illustrated in  FIGS. 7 and 8B ). Multiple bolts or rivets are used to attach end sections to the collar to prevent the sections from rotating independently. The steps may be repeated to form another transverse end assembly. 
     B. Formation of the Support Assembly 
     The support assembly may be assembled a number of ways. 
     1. Transverse Ribs Stationary 
     In one instance, longitudinal rails are inserted into a stationary transverse rib. The rails may be inserted through two or more stationary ribs, or the rails may be inserted through one or more stationary ribs and one or more stationary end pieces. This method retains the rails in an array, and additional ribs and/or end pieces may be added to continue forming the support assembly. 
     The ribs may be secured in the desired position along the length of the longitudinal rails by e.g. placing set-screws into the longitudinal rails, providing stops on the rails such as collars, or otherwise clamping or holding the ribs along their sides. The ribs may be secured instead or in addition by screwing, bolting, riveting, welding, or adhering the ribs to the longitudinal rails through the ribs. 
     Likewise, transverse end sections may be secured to the longitudinal rails by clamping or securing them from their sides or through the end sections and into the rails. The end plates or sections may therefore be secured by providing stops or collars on the rails, tacking the sides or bottoms of the end sections to the rails, bolting, screwing, riveting, or otherwise securing the end sections from their sides or through their bodies to the longitudinal rails. 
     2. Transverse End Assembly Stationary 
     In another instance, assembly commences by holding one of the transverse end sections stationary and inserting rails into it. One or more ribs may be in place, or the rails may be held in position temporarily by stands and/or a stand that holds the rail ends. Ribs may be slipped onto the rails to form the support assembly, and the ribs may be secured to the rails as discussed above. A second end section may be placed on the ends of the rails to form the support assembly. The ribs and end sections may be secured to the rails as discussed above. 
     3. Longitudinal Rails Stationary 
     In one instance, longitudinal rails are held stationary by e.g. one or more stands, and ribs are slipped onto the array of rails and secured as discussed above. End sections are placed onto and secured to the rails as discussed previously. 
     C. Assembling Optional Housing Panels 
     In one instance, housing panels may optionally be installed on the outside of the support assembly to provide structural rigidity. One or more panel locks may be secured to the end longitudinal rails at transverse ends of the support assembly using screws to secure the edges of the housing panels. The panel locks may be longitudinal cross-bars beneath which edges of the housing panels fit, or panel locks may be e.g., individual clamps that clamp edges of the panels. The panel locks may be two parallel cross-bars that are used as a clamp to secure the edges of the housing panels. The panel locks may be attached to the end rails, and/or the panel locks may be attached to ribs. The housing panels may also be secured to the ribs if desired to provide a more rigid structure. The housing panels may be large enough to span the entire width of the support assembly, or housing panels may span about half the width of the support assembly. A bottom panel lock may cover adjacent housing panels where half-width panels are used and also secure the panels in place. In some variations, two adjacent half-width housing panels may be riveted together without using a panel lock. 
     D. Assembling Solar Energy Collecting Panels 
     As noted above, solar energy collecting panels may be photovoltaic panels, an array of tubes through which water or oil flows, and/or minors that reflect light to a tube through which water or oil or another medium to be heated flows. Solar Energy collecting panels may be flexible or rigid. Collecting panels may have a width that spans the entire width of the support assembly, so that ends of the individual reflector panels fit beneath the end panel locks. Alternatively, collecting panels may span about half the width of the support assembly, in which case one end of the panels fits beneath an end panel lock and one end of the panels fits beneath a center panel lock that is secured to ribs and/or to the optional housing panel rail lock located on the outside of the support assembly. 
     Once the framework of the support assembly is formed and optional housing panels are installed as discussed above, one or more panel locks may be placed on the ribs and secured by welding, adhering, riveting, bolting, or otherwise securing the longitudinal cross-bars to the ribs. The panel locks may be longitudinal cross-bars beneath which edges of the solar energy collecting panels fit, or panel locks may be e.g., individual clamps that clamp edges of the panels. The panel locks may be two parallel cross-bars that are used as a clamp to secure the edges of the housing panels. In some variations, panel locks may be U-shape cowlings that enclose the edges of collecting panels and the end longitudinal rails. A longitudinal cross-bar, beneath which edges of the solar energy collecting panels fit, may optionally be enclosed inside the cowling to provide a riveting surface. 
     If panel locks are secured to the ribs at both transverse ends of the structure assembly, panels such as solar energy collecting panels may be slipped longitudinally into the support assembly from one or both longitudinal ends. The panels may be flat, especially if the ribs are flat rather than parabolic in shape, or the panels may be shaped to conform to the ribs&#39; curvature. In one instance, the panels are flexible minor panels that can be curved into e.g. cylindrical or parabolic profile and slid into place. The panels may be secured to the ribs, or the panels may rest upon the ribs. 
     If panel locks are secured to the ribs at one transverse end of the support assembly first, the collecting panels may be placed upon the ribs transversely rather than longitudinally. The panels are placed into the desired positions, and the longitudinal secure bars may then be secured to the ribs at the other transverse end of the support assembly. 
     Solar energy collecting panels may be held in place by transverse panel-retaining strips that run transversely between and atop adjacent collecting panels. Transverse panel retaining strips may be e.g. adhered, bolted, riveted, screwed, or otherwise secured to ribs or end sections. The retaining strips can provide deformable collecting panels with a regular, little-deformed curvature that can result when, for example, flexible panels are riveted or bolted to the support assembly through its ribs, longitudinal rails, and/or end sections. Retaining strips may be inserted between or placed upon adjacent collecting panels to help secure transverse edges of the collecting panels and assure the desired flat, cylindrical, or parabolic shape of the collecting panels. Individual retaining strips may be secured to end panel locks, central panel locks, and/or transverse ribs. 
     Once solar energy collecting panels are installed, optional torsion cables (e.g., guy wires) may be secured to diagonally opposite end assemblies and adjusted using turnbuckles to tension the end arms and longitudinal rails to provide a more rigid assembly. Smooth-surfaced end caps may also be placed upon ends of longitudinal rails to provide finished ends to the rails. 
     E. Assembling Collector Tube and Supporting Stanchions 
     In a solar energy collector, one or more stanchions may be attached to the support assembly to support a collector tube upon which solar energy is focused or collected. A stanchion may be secured to a transverse panel-retaining strips and/or rib by e.g., screwing, bolting, riveting, and/or adhering the stanchion to the strips and/or rib. The stanchions are first installed with the top half of the slit ring removed (as illustrated in  FIG. 39 ). Bearings and/or mount tubes used to support the collector tube in each stanchion may first be slid onto the collector tube. Collector tube is then placed upon the stanchions and inserted through mount collars located at both ends of the collector. The top half ring may then be placed on the stanchion with set-screws attached. 
     Once the collector tube is installed, a laser device may be used to adjust the position of the collector tube. The laser device may be a standard device that emits laser beam, which may be used to test the focus lines and/or surfaces of a solar energy collector. Alternatively, such laser device may be proprietary. In one instance, after a solar energy collector is assembled, a laser device may be placed on a horizontal bar across the opening of the parabolic-shaped collector. The reflection of the laser beam will be examined while the laser machine moves from one end of the bar to the other. The position of the collector tube may be adjusted by the set-screws on the stanchions, the set screws on the mount collar, and/or the tension of the panel-retaining bars to ensure the reflection of the laser beam falls upon the collector tube. Alternatively, an assembler of a solar energy collector may shine a bright light upon the reflector from directly above and adjust the set-screws to provide the desired pattern of illumination on the collector. 
     F. Ganging Adjacent Collectors 
     Two adjacent solar energy collectors may be ganged together by coupling one or more pairs of longitudinal rails with a joining pipe (as illustrated in  FIG. 18 ). The joints may be connected to the longitudinal rails by interference fit or other types of suitable fittings. 
     G. Assembly Rack 
     In some variations, parts of support assemblies and solar energy collection systems described herein may be shipped unassembled and assembled on site or near site by local installers. It is desirable to simplify and optimize the assembling process since often times rows of collectors need to be assembled for solar applications. Assembly racks may be used to help reduce the manpower and time required to assemble collectors. For example, a rack may be used to hold different parts and components of a collector in place, therefore restraining relative motion between different parts and allowing the installer to work on the installation. As another example, a rack may comprise holders, clips or clamps at pre-determined locations to hold parts in place, thereby avoiding on-site measurements and enhancing installation consistency and accuracy. A rack may also comprise various configurations adapted to use at different stages of assembly, further simplifying installation process. In still other variations, different racks may be used for different stages of assembly to felicitate an assembly line approach. 
       FIGS. 57A to 57F  illustrate one variation of an assembly rack used to assemble a support assembly for a trough solar energy collector. The rack  5700  comprises a bottom rectangular base  5705  formed of two longitudinal pieces  5704 , two transverse pieces  5706  and a plurality of optional cross pieces  5708 . All pieces that form the base  5705  may be stamped or pressed from a sheet of e.g., stainless steel or aluminum. As illustrated in  FIG. 57C , the transverse piece  6706  has triangular-shaped ends, which, along with the triangulated structures created by optional cross pieces  5708 , may enhance the rigidity of the base structure. Base pieces may be assembled by welding, soldering, screwing, riveting, bolting or other types of suitable attachment methods. Four end assembly brackets  5712  are mounted at four corners of the rectangular base  5705 , configured to hold two end assemblies of the trough collector in place by fitting the edge of the end assembly in an upright slot  5713 . Between two end assembly brackets  5712 , a plurality of rib brackets  5714  are mounted along the longitudinal piece  5704  of the base  5705 . The number of rib brackets  5713  may be the same as the number of ribs used in the trough collector to be assembled. In some variations, there may be more rib brackets than ribs to be assembled on the assembly rack  5700  such that the rack  5700  may be also used for collectors designed with more ribs. The rib brackets  5714  are located at pre-determined locations on the longitudinal piece  5704  to ensure proper rib spacing. In some variations, each bracket (rib bracket or end assembly bracket) may be movable in the lateral direction to allow better alignment between the two transversely corresponding brackets. In the example shown here, the upright slot  5715  in a rib bracket  5714  is narrower than the slot  5713  in an end assembly bracket  5712  because the corner bracket  5712  will receive both end assembly and a rib attached thereto. The width of the slot on both rib bracket and end assembly bracket also depends on the specific design of the rib and the end assembly. As noted above, a rib may be formed of two rib plates, which will need a wider slot, or a single rib plate, which will need a narrower slot. This applies to the end assembly as well. As a result, different sets of brackets with different slot width may be used in conjunction with one rectangular base. Brackets may be easily exchanged (e.g., unscrewed from the longitudinal piece) to assemble collectors with a different rib or end assembly design. Alternatively, brackets may be made from a flexible and/or resilient material such that one bracket may be used for rib/end assembly with an either single-plate design or a double-plate design. 
     The rack  5700  also comprises an elevated central beam  5740  configured to provide support to the apex, minimum, or vertex of the parabolic ribs. As illustrated in  FIG. 57D , a supporting member  5732  is coupled to the central beam  5730  to receive a rib in an upright slot  5733 . The central beam  5730  is supported by two end stanchions  5742 , which are mounted on the transverse base pieces  5706 . A supporting strut  5744  may optionally attached to the end stanchion  5742  to provide lateral support to the end assembly, as illustrated in  FIG. 57E . 
     To assemble a support assembly, an installer may first place an end assembly and a rib at both ends of the assembly rack  5700 . They may be held in place by end assembly brackets  5712  vertically and the supporting struts  5744  laterally. The rest of ribs may be then placed in rib brackets  5714 . The ribs will be held at both ends by brackets  5714  and be supported at the center by the supporting member  5732 . At this point, longitudinal rails ( 5701  to  5703  are shown in  FIG. 57A ) may be slid in and secured to the ribs and/or end assemblies. The rack  5700  may also be used for the next installation step—housing panel installation. As noted above, two housing panels may be overlapped at the apex, minimum, or vertex of the trough and secured to one another by rivets. As illustrated in  FIG. 57F , a metal backing for a rivet may be provided by the combined structure of two side “C”-shaped clips and one middle “U”-shaped clip. 
     Upon completion of the housing panel installation, the support assembly may be flipped over to have other parts, such as solar energy collecting panels installed. Installing colleting panels with the support assembly facing upward may be challenging. If the support assembly rests on the ground, additional worker may be needed to hold the collector up in place. Another option is to use stands on the ends of the trough collector as it would be supported during normal operation. However, by supporting the support assembly at the ends, a lack of support in the middle portion of the trough may cause the support assembly to dip. This may impede collecting panel installation because there could be uneven conforming forces along the collecting panels. 
       FIG. 51  illustrates another variation of an assembly rack  5100  that comprises a rectangular area where a partially finished support assembly  5102  may be placed with the solar collecting side facing upward. The rack  5100  helps support the support assembly  5102  along the entire longitudinal length so that the collecting panels may more easily slide into place. This upward facing position may be also useful for installing the end cowlings that wrap around the edges of the collecting panel and/or other accessories that may be added to the inside of the collector, such as stanchions and guy-wires. The assembly rack  5100  may also help prevent the support assembly  5102  from rotating. 
     Instead of using two different racks for various stages of assembly, one assembly rack with various configurations may be used.  FIGS. 58A to 58C  illustrate one example of a multi-purpose assembly rack  5800 . As illustrated in  FIG. 58A , the assembly rack  5800  comprises a hollow rectangular base  5802  with a surface  5804  wide enough to have a plurality of rib brackets  5812  mounted upon. Two side wings  5822  may be placed in the hollow region of the base  5802  to hold a trough collector facing upward. In some variations, these wings  5822  may be removed from the base  5802 . In other variations, the wings  5822  may be foldable structures that may be folded into the hollow region of the base  5802  when not being used. In still other variations, the height of the wings  5822  may be adjusted to permit ergonomic operation. As illustrated in  FIG. 58B , two side wings  5822  may be replace with a plurality of side brackets  5812  to support an upward facing trough collector. The middle portion of the collector may be supported by a supporting structure  5832  placed in the hollow region of the rectangular base  5802  to prevent the middle portion from dipping. In this specific embodiment, the supporting structure  5832  has an “X” shape and may also provide reinforcing effect to the base  5802 . In other variations, the supporting structure may have other configurations.  FIG. 58C  illustrates how the assembly rack  5800  may also be used to support a downward facing trough collector by placing ends of ribs into the slots of the side brackets  5812   
     In other variations, an assembly rack may also have convertible pieces and sizes that enable it to be used for different size collectors. For example, the surface  5804  of the rectangular base in the examples shown in  FIGS. 58A to 58C  may cover more surface area so that the side brackets  5812  could move to different widths for different sized ribs and end assemblies. Once it is adjusted to the proper width, the side brackets may then be locked into place to prevent the ribs and end assemblies from moving. Similarly the side wings  5822  or the assembly rack  5104  shown in  FIG. 51  may have adjustable sizes to support different sizes of trough collectors or to adjust the height. This may add to the versatility of the rack and allow the installers to work at a height most comfortable to them. In some variations, legs of an assembly rack used to support upward facing collectors may have different height settings (e.g., different width and/or height). In other variations, the side wings may vary in angle or length. 
     V. One Example of a Trough Solar Energy Collector and Method to Assemble 
       FIGS. 49A to 49E  illustrate another example of trough solar energy collector  4900 . When in collecting operation, trough  4900  tracks the movement of the sun and focus and direct the radiant energy of the sun into a heat collector tube  4932  that heats a working fluid which is then used for various applications, including, but not limited to generate steam, which is then used to for electricity, desalination, absorption cooling for HVAC and refrigeration, electrolysis, reformation, and hot water. 
     The exemplary trough collector  4900  may be about 12 feet long (excluding the stands at both ends), about 5 feet 2 inches wide and about 3 feet 11 inches high. The trough collector  4900  comprises a collector body rotatablely mounted between a motor stand  4901  and a drive stand  4902 . The collector body with a generally parabolic shape further comprises a plurality of longitudinal rails (e.g., two end longitudinal rails  4905  disposed at two transverse ends of the trough, two center longitudinal rails disposed at the center, apex, minimum, or vertex of the trough, two longitudinal rails each disposed between the end rail and the center rail but closer to the end rail) held longitudinally between two end assembly  3  and transversely by a plurality of parabolic-shaped transverse ribs  4904 , which are spaced evenly between two end assembly  4903 . The collector body is covered on its outside by two oppositely-facing housing panels  4913  with each longitudinally spanning the length of the longitudinal rails  4905  and  4906  and transversely spanning from one end rail  4905  to a center rail  4906 . Two housing panels  4913  may overlap at the center, apex, minimum, or vertex of the trough and the overlapped portions of the housing panels may be riveted together. Three juxtaposed solar energy collecting panels  4912  are placed on the inner surface of the frame formed by the longitudinal rails  4905 ,  4906  and transverse ribs  4904 . The edges of the collecting panels  4911  are secured at both end of the trough between an inner cowling  4910  and an outer cowling  4909 . The collecting panels  4911  are attached to the upper surface of the ribs  4904  by a plurality of transverse retaining strips  4911 , thereby assuming a generally parabolic shape. A heat collector tube is positioned approximately coincidentally with the line focus of parabolic collecting panels  4912  to receive light reflected by the collecting panels  4912 . The collector tube extends through a mount collar  4938  at each end of the trough and into a supporting bracket  4914  on top of the collector stand (e.g., a drive stand  4902  or a motor stand  4901 ). A mount tube  4907  or  4908  is disposed within each mount collar  4938  to receive the collector tube  4932 , therefore removing the weight of the trough collector from the collector tube. A bearing  4937  (e.g., a graphite bearing) may be placed between the collector tube  4932  and the mount tube  4907  and  4908  to reduce friction and facilitate collector rotation. A motor  4936  with a drive shaft  4932  coupled to the motor shaft is used to drive the rotation of the trough collector to track the sun. The sprocket assembly or other types of transmission system that may be used to transmit the motor&#39;s torque output to the trough collector is not shown here. A collector tube sleeve assembly may be used to improve the thermal performance of the collector tube  4932 . The sleeve assembly may comprise a glass tube  4928  with a slot  4929  along its longitudinal length, a movable cover  4925  configured to cover and seal the slot  4929  during collector&#39;s operating motion, a reflective strip  4926  designed to focus and reflect back additional light captured by the strip  4926  to the collector tube  4932 , and seals  4926  used to seal the slot  4929  of the glass tube  4928  and/or ends of the glass tube  4928 . In this specific example, the cover  4925  has curved configuration with an opening slight larger than the width of the slot  4929  on the glass tube  4928  such that the cover  4925  may be secured to the glass tube  4928  along the slot  4929  by riveting, screwing, bolting, or mechanical locking (e.g., brackets or clamps). In this variation, the reflective strip has about the same longitudinal length as the cover  4925 . It also has a curved configuration with a radius about the same as that of the curved cover  4925 . The reflective strip  4526  may be secured to the inner surface of the cover  4925  by the same attachment method that may be used to secure the cover  4925  to the glass tube  4928 . For example, one screw may extend through the cover  4925 , the reflective strip  4926  and the glass tube  4928  to secure them together. The seal  4927  may be made from any of a variety of materials that are pliable or resilient to allow thermal expansion without undue stress being created on the glass tube  4928 , the cover  4925  and the collector tube  4932 . As one specific example, the seal may be silicone foam. 
     The trough collector  4900  may comprise three sets of sleeve assemblies that may be used to cover a portion of the collector tube between one end assembly and a first stanchion, between the first stanchion and the second stanchion, and between the second stanchion and the other end assembly, respectively. Such arrangement simplifies the assembly and maintenance process since the sleeve assembly may be assembled and removed without disturbing the collector tube. In some variations, the slotted glass tube  4928  may be positioned so that the slot is underneath the collector tube  4932 . In other variations, the slot may be positioned above the collector tube. In some variations, the glass tube  4928  and the cover  4928  are stationary while the trough collector pivots to track the sun. In other variations, the glass tube  4928  and the cover  4925  may be attached to the end assembly and/or stanchions such that they will move in concert with the trough collector. 
     To assemble a trough collector  4900 , an assembly rack  5000  as illustrated in  FIG. 50  may be used to first set up transverse ribs  4  and end assemblies  3  for later rail insertion. The rack  5000  has a rectangular base of about the same longitudinal length as the longitudinal rail  4905  or  4906  and about the same transverse width of the transverse rib  4904 . There are seven evenly spaced brackets  5004  on each longitudinal side of the racket  5000  that are configured to receive the ends of seven transverse ribs  4904 . The bracket  5000  also has a center beam  5002  elevated to a height configured to support the center, apex, or minimum point of the parabolic rib. The center beam  5002  is shorter than the longitudinal side of the bracket  5000  to leave room for two end assemblies  4903 . If the ribs have bent edges as discussed above, the installer should examine the assembly to ensure all ribs are oriented correctly. The installer may also mark the end assembly North or South depending upon the collector&#39;s proximity to the motor. The geographic orientation of the trough collector may be relevant when the sprocket assembly is installed. 
     Once the ribs  4904  and end assemblies  4903  are set up on the bracket, longitudinal rails  4905  and  4906  are inserted into corresponding mounting holes in the ribs  4904  and end assemblies  4903 . Before placing the housing panels  4913 , the installer first bores out mounting holes on the bent edges of the ribs  4904 . A housing panel may be riveted through the one top mounting hole in the center rib such that the panel may hang level while the installer place the rest of the rivets, working from the center rib toward the ribs attached to the end assemblies. A second housing panel may be placed on the ribs similarly with a longitudinal strip overlapped with the first panel. The installer can use a drill template to bore out evenly spaced rivet holes on the overlapped strip of the two housing panels and rivet the two panels together. 
     Once the housing panels are installed, the partially finished trough collector  5102  may be flipped over and placed on another assembly rack  5104 , as illustrated in  FIG. 51 . The rack  5104  has a rectangular opening that may receive and support the collector  5102  to allow the installer to finish the remaining steps to assemble the support frame. First, the ribs may be secured to the longitudinal rails by tanging a rib to the rail and creating a dimple on the rim of the mounting hole in the rib (shown in  FIG. 40 ). The inner cowlings then may be placed on both ends of the trough collector. 
     Prior to the collecting panel installation, temporary alignments shafts (e.g., thread rods or bolts  4330  in  FIG. 43 ) may be placed on the ribs at locations where collector tube stanchions will be installed later. The middle collecting panel may be placed first followed by the placement of two side panels. Once three collecting panels are property aligned, two outer cowlings may be placed outside the inner cowlings with the edges of the housing panels and the collecting panels clamped between the two cowlings. Temporary alignment shafts may be removed at this point and transverse retaining strips then may be placed on the surface of the collecting panels to secure the panels to the ribs underneath. In this particular trough collector, two retaining strips are placed over the center of two adjacent colleting panel seams, thereby securing both panels to the rib underneath the strip. Another two strips are used to secure the two side panels to the two end ribs. For the two retaining strips located adjacent to the end assemblies, one edge of the flattened strip head may be trimmed to ensure better alignment with the end assemblies (as illustrated in  FIG. 44 ). Ends of the retaining strips may then be attached to the outer cowlings by screws or other types of fasteners. Heat collector stanchions may then be installed on the retaining strips before the strips are tightened to be flush with the solar collecting panels. In this particular trough collector as illustrated in  FIG. 52 , two screws  5202  are used to secure each stanchion  19  on the transverse retaining bar  18 . Each stanchion  19  has a top bracket  5204  configured to support the heat collector tube and other parts used in conjunction with the collector tube, such as tube bearing, mount tube, stanchion gasket, etc., may extend. The top half of the stanchion bracket  5204  may be installed after the collector tube is installed in the filed. A bottom half of a mount collar bracket configured to support the collector tube when it extends through the mount collar at the end of the trough collector may then be installed on each end assembly located underneath the mount collar. 
     At this point, the screws that hold the transverse retaining bars to the outer cowlings may be tightened to ensure secure placement of the collecting panels. Screws used in other parts of the trough collector may be all tightened at this point to about 60 lbf. In some variations, the large-diameter sprocket may be installed onto the collector before the collector is moved into the filed to form a row. Variations of attachment methods to install the large sprocket have been described in detail above. 
     VI. An Example of a Row of Trough Collectors and Method to Assemble 
     A plurality of trough collectors  4900  may be assembled into a row or a linear array of collectors. A row of trough collectors may have any number of individual collectors, depending in part on the applications for the thermal energy collected and generated by the trough collectors, the real estate arrangement and the design of the drive system to drive the row to track the sun. 
     As one specific example shown in  FIG. 53 , a row of trough collectors  5300  is assembled generally extending in a north-south direction to track the east-west processing of the sun throughout a day. The row  5300  comprises one motor mounted on a motor stand  5304 , which is located in the middle portion of the row  5300 , and  14  trough collectors (No. 1 to No. 14), 7 of which are located north of the motor (No. 1 to No. 7) and 7 are located south (No. 8 to No. 14). The row  5300  further comprises 4 sets of sprocket assembly ( 5306  to  5309 ), two of which ( 5306  and  5307 ) are installed at the south ends of two trough collectors (No. 2 and No. 5, respectively) located north of the motor and two of which ( 5308  and  5309 ) are installed at the north ends of two trough collectors (No. 10 and No. 13, respectively) located south of the motor. In some variations, because of the width of the motor, the spacing between two trough collectors for motor stand  1  placements may be larger than that for drive stand  2  placements. As a result of such larger spacing, the drive tube  8  and/or the drive shaft  32 , which are coupled to the motor stand  1  may be longer than their counterparts that are used in conjunction with drive stand  2 . 
     It is noted that this layout of the trough collectors, motor and sprocket assembly is only exemplary. Different layout may be used in other variations. For example, a row of collectors may comprise more or less than 14 individual collectors. Further, more than one motor may be used to drive a row of collectors to track the sun. Even if only one motor is used, it may be located at a location other than the middle point of the row. For example, the motor may be at either the south end or the north end of one row. The number of intermittent sprocket assembly used in one row of collectors may vary, depending in part on the number of collectors in one row and/or the torque output of the motor(s) used to drive the rotation of the row. 
     Before trough collectors are assembled in the field to form a row, collector stands (e.g., motor stand  1  and/or drive stand  2 ) are first mounted on concrete bases. A drive stand  5404 , mounted on a concrete ground base  5406 , is illustrated in  FIG. 54 . In some variations, the stand  5404  may be shimmed with washers  5410  to ensure that the stand is plumb. When a stand is mounted properly, a drive shaft bracket  5408 , as well as the bearing  5412  and the drive shaft coupler  5410  may be assembled at this point. 
     The installation of the drive system may begin with the installation of the motor  4936  with a gear box onto the motor stand  4901 . Two drive shaft tubs may then be slid onto both sides of the motor shaft, extending opposite directions (e.g., north and south), respectively. The other end of each drive shaft tube is then placed into the drive shaft bracket of the drive shaft stand located next to the motor stand (e.g., either north of the motor stand or south) in the row. These two drive shaft tubes may be further extended by coupling another drive shaft tube using the drive shaft coupler, variations of which have been described above. This step to install drive shaft may be repeated for each trough collector in the row. In some variations where the spacing between two collectors for motor stand is larger than that of drive stand, the drive shaft disposed between the motor stand and the drive stand is therefore longer than the drive shaft disposed between two drive stands. 
     The small-diameter sprockets and chains may be installed at pre-selected locations before the drive shaft tubes are extended at such locations. A small sprocket  4604  may be first slide onto the end of a drive shaft tube  4606  that extends through and over a drive shaft bracket  4610 , as illustrated in  FIG. 46 . Another drive shaft tube  4607  may be then placed onto the drive shaft coupling (e.g., the drive shaft coupler  4602  with insertion of a key shaft) to extend the drive shaft. The installer may adjust the position of the small sprocket to ensure it is plumb to the large sprocket located thereabove. The small sprocket may be secured to the drive shaft by one or more set screws. When both sprockets are in place, a chain tensioner assembly may be assembled and installed on the drive shaft. 
     Before the heat collectors are installed, mount tubes (e.g.,  4907  and  4909  in  FIG. 49E ) and mount bearings (e.g.,  4915  in  FIG. 49E ) may be first installed for each trough collector starting from an end collector in the row. As illustrated in  FIG. 55 , a mount tube  5502  may be first inserted into the mount collar  5504  at one end of the trough collector  5500 . The mount tube  5502  may be secured to the mount collar  5504  by a key shaft (not shown) and one or more set screws  5506  in the mount collar  5504 . The key shaft used here may or may not be of the same size and/or shape as the key shaft (e.g.,  4512  in  FIG. 45 ) used to joint drive shaft (e.g.,  4508  in  FIG. 45 ). A bearing may be then slid onto the mount tube. The same installation steps may be repeated at the other end of the collector. Upon completion of installing two mount tubes and bearings, the collector may be lifted to place two extended mount tubes over the center of two stands. The top half of the collector bracket may be placed and secured with the bottom half with bolts  17  and plate washers  16 . The exposed portion of the drive tube will be inserted into the mount collar of next trough collector in the row. It is noted that the mount tube placed on a motor stand may be longer than the mount tube located on a drive stand because of the larger spacing for the motor stand as discussed previously. 
     The heat collector for one row of trough collectors may be a single tube or a plurality of tubes joined by welding or other types of attachment methods. When a plurality of collector tubes are welded together, the weld joints may be positioned away from locations where the collector tube may bear stress and/or strain. For example, the installer may avoid contact between weld joints and bearings (e.g., mount collar bearings, stanchion bearings or stand bearings). Once the mount tubes have been set up, the heat collector tube may be inserted from one end of the row to the other. A plurality of bearings may be slid onto a collector tub before the tube exits from each collector. For the exemplary collector illustrated in  FIG. 49 , four bearings may be slid onto the tube, two of which are used in conjunction with the tube stanchions and two of which are used in conjunction with the tube brackets attached on the collector end assemblies. Once the collector tube has been installed, three sets of sleeve assemblies may be installed for each trough collector by first placing the slotted glass tube upon the collector tube. Silicone form seals may be placed along both edges of the slot and at both ends of the sleeve assembly. The pre-determined length of the sleeve assembly allows the glass tube with the cove to fit between two bearings (e.g., either two stanchion bearings or between one mount collar bearing and one stanchion bearing) while leaving room for thermal expansion and contraction. Silicone form may be placed between the end of each sleeve assembly and bearings to reduce heat loss. When seals are placed properly, the cover with the reflector strip placed underneath the cover may be screwed upon the glass tube to cover and seal the slot. Upon completion of the collector tube installation, the position of the collector tube may be adjusted by the screws on the stanchion bearings or mount collar bearings. 
     Therefore, by way of illustration but not by way of limitation, the following are specifically envisioned as various embodiments of the invention:
         1. A trough solar energy collector, comprising:
           a support assembly for supporting one or more solar energy collecting panels, said support assembly further comprising:
               (a) a plurality of longitudinal rails;   (b) a first transverse rib and a second transverse rib both secured to said plurality of longitudinal rails, wherein each of said ribs has a shape approximating an arc of a cylindrical or parabolic surface; and   (c) a first end assembly and a second end assembly both secured to said plurality of longitudinal rails;
                   wherein a first of said plurality of longitudinal rails is positioned at an apex, minimum, or vertex of said cylindrical or parabolic surface;   
                   
               at least one solar energy collecting panel; and   a collector tube positioned to receive light reflected by said collecting panel.   
           2. A trough solar energy collector, comprising:
           a support assembly for supporting one or more solar energy collecting panels, said support assembly further comprising:
               (a) a plurality of longitudinal rails;   (b) a first transverse rib and a second transverse rib both secured to said plurality of longitudinal rails, wherein each of said ribs has a shape approximating a chord of a cylindrical or parabolic surface; and   (c) a first end assembly and a second end assembly both secured to said plurality of longitudinal rails;
                   wherein a first of said plurality of longitudinal rails is positioned at an apex, minimum, or vertex of said cylindrical or parabolic surface;   
                   
               at least one solar energy collecting panel, said collecting panel being secured to said support assembly by at least one panel-retaining strip; and   a collector tube positioned to receive light reflected by said collecting panel.   
           3. The trough collector according to paragraph 1 or paragraph 2, further comprising a second longitudinal rail positioned at an apex, minimum, or vertex of said cylindrical or parabolic surface.   4. The trough collector according to paragraph 1 or paragraph 2, wherein said plurality of longitudinal rails comprises a single longitudinal rail positioned at an apex, minimum, or vertex of said cylindrical or parabolic surface.   5. The trough collector according to any of paragraphs 1 to 4, wherein said plurality of longitudinal rails comprises a first end longitudinal rail along a first longitudinal edge of said cylindrical or parabolic surface, and a second end longitudinal rail along a second longitudinal edge of said cylindrical or parabolic surface.   6. The trough collector according to paragraph 5, wherein said first end longitudinal rail and said second longitudinal rail have a larger outer diameter than the rest of said plurality of longitudinal rails.   7. The trough collector according to any of paragraphs 1 to 6, wherein each of said first and second transverse ribs comprises two rib sections; said each rib section transversely spanning half of said cylindrical or parabolic surface and abutting all adjacent rib section at an apex, minimum, or vertex of said cylindrical or parabolic surface.   8. The trough collector according to paragraph 7, wherein said two rib sections of each transverse rib overlap at an apex, minimum, or vertex of said cylindrical or parabolic surface; the overlapped portion of two rib sections having a first mounting hole configured to receive a first of said plurality of longitudinal rails.   9. The trough collector according to paragraph 8, wherein said overlapped portion of two rib sections further have a second mounting hole configured to receive a second of said plurality of longitudinal rails.   10. The trough collector according to any of paragraphs 1 to 9, wherein each of said transverse ribs or each of said rib sections has at least a portion of its edge bent to about 90 degrees with respect to the plane of said rib or rib section.   11. The trough collector according to any of paragraphs 1 to 10, wherein each of said transverse ribs or each of said rib sections comprises a single piece.   12. The trough collector according to any of paragraphs 1 to 10, wherein each of said transverse ribs or each of said rib sections comprises a first side piece, a second side piece and a spanning piece extending from said first side piece to said second side piece.   13. The trough collector according to paragraph 12, wherein said spanning piece comprises a “U”-shaped piece attached to said first side piece and said second side piece.   14. The trough collector according to any of paragraphs 7 to 9, wherein each said rib section comprises a first side piece, a second side piece and a spanning piece extending from said first side piece to said second side piece, and wherein said rib sections are interdigitated such that the first side piece of the first rib section is adjacent the first side piece of the second rib section and the second side piece of the first rib section is adjacent the second side piece of the second rib section.   15. The trough collector according to paragraph 14, wherein said first side piece and said second side piece are identical.   16. The trough collector according to any of paragraphs 7 to 14, wherein said rib sections are identical.   17. The trough collector according to paragraph 1 or paragraph 2, wherein each of said transverse ribs is a single piece that spans all said longitudinal rails.   18. The trough collector according to any of paragraphs 1 to 17, wherein each said end assembly is T or Y shaped.   19. The trough collector according to any of paragraphs 1 to 18, wherein each said end assembly comprises a first two identical pieces adjacent to and 180 degrees to one another in the plane within which said two pieces lie.   20. The trough collector according to paragraph 19, wherein each said identical pieces comprises an “L”-shape.   21. The trough collector according to paragraph 19 or 20, wherein said two identical pieces overlap; the overlapped portion of two identical pieces having a first mounting hole configured to receive a first of said plurality of longitudinal rails.   22. The trough collector according to paragraph 21, wherein said overlapped portion of two identical pieces having a second mounting hole configured to receive a second of said plurality of longitudinal rails.   23. The trough collector according to any of paragraphs 19 to 22, wherein each said end assembly comprises a second two identical pieces arranged identically to said first two identical pieces, said first two and said second two identical pieces being separated by spacers, and a spanning piece spanning a gap between said first two identical pieces and said second two identical pieces, wherein said end assemblies are interdigitated such that a first piece of said first two identical pieces is adjacent a first piece of said second two identical pieces and a second piece of said first two identical pieces is adjacent a second piece of said second two identical pieces.   24. The trough collector according to any of paragraphs 1 to 23, wherein each of said first end assembly and second end assembly abuts one said transverse rib to triangulate each longitudinal end of said trough collector.   25. The trough collector according to any of paragraphs 1 to 24, further comprising at least one housing panel secured to one side of said support assembly that is opposite to the solar energy collecting side.   26. The trough collector according to any of paragraphs 1 to 25, further comprising a first housing panel and a second housing panel, said first housing panel transversely spanning half of said trough and said second housing panel transversely spanning the other half of said trough, and wherein said first housing panel and said second housing panel abut at an apex, minimum, or vertex of said cylindrical or parabolic surface.   27. The trough collector according to any of paragraphs 1 to 26, wherein said panel-retaining strip is a cowling positioned around one said longitudinal rail located at one transverse end of said trough collector.   28. The trough collector according to paragraph 27, further comprising a second cowling, wherein said second cowling is disposed around said first cowling with an edge of said solar energy collecting panel positioned between said first cowling and said second cowling.   29. The trough collector according to paragraph 27 or paragraph 28, wherein each of said first cowling and said second cowling has a “U”-shape.   30. The trough collector according to any of paragraph 27 to 29, further comprising at least one transverse panel-retaining strip, wherein said strip spans all said longitudinal rails.   31. The trough collector according to any of paragraphs 1 to 26, wherein said strip is a retaining strip securing adjacent collecting panels to a rib and spanning all longitudinal rails.   32. The trough collector according to any of paragraphs 1 to 26, wherein said strip is a first longitudinal cross-bar disposed at a transverse end of said cylindrical or parabolic surface.   33. The trough collector according to paragraph 32, further comprising a second longitudinal cross-bar, wherein an edge of said solar energy collecting panel is secured between said first cross-bar and said second cross-bar.   34. The trough collector according to paragraph 32 or paragraph 33, further comprising at least one transverse panel-retaining strip, wherein said strip spans all said longitudinal rails.   35. The trough collector according to any of paragraphs 28 to 30, wherein an edge of said housing panel positioned between said first cowling and said second cowling.   36. The trough collector according to any of paragraphs 1 to 34, further comprising a longitudinal housing-panel-retaining cross-bar disposed at a transverse end of said cylindrical or parabolic surface.   37. The trough collector according to paragraph 36, further comprising a second longitudinal housing-panel-retaining cross-bar, wherein an edge of said housing panel is secured between said first cross-bar and said second cross-bar.   38. The trough collector according to any of paragraphs 1-37, further comprising a first center longitudinal cross-bar disposed at an apex, minimum, or vertex of said cylindrical or parabolic surface and configured to secure said solar energy collecting panel to said support assembly.   39. The trough collector according to any of paragraphs 1-38, further comprising a second center longitudinal cross-bar disposed at an apex, minimum, or vertex of said cylindrical or parabolic surface and configured to secure said housing panel to said support assembly.   40. The trough collector according to any of paragraphs 1 to 39, further comprising a plurality of solar energy collecting panels, wherein said panels are secured to one side of said support assembly adjacent one another with at least one said panel-retaining strip engaging two adjacent said panels, and each of said panels spans all said longitudinal rails.   41. The trough collectors according to any of paragraphs 1 to 40, wherein said solar energy collecting panel is elastically deformable and assumes a parabolic or cylindrical shape upon placement on said support assembly   42. The trough collector according to any of paragraphs 1 to 41, further comprising guy wires securing a first end of said support assembly to a second end of said support assembly and passing over collecting surface of said collecting panel.   43. The trough collector according to any of paragraphs 1 to 42, further comprising a transparent thermal insulating sleeve positioned around said collector tube.   44. The trough collector according to paragraph 43, wherein said sleeve has a slot along at least the majority of the longitudinal length of said sleeve.   45. The trough collector according to paragraph 44, wherein said slot is larger than the outer diameter of said collector tube.       

     46. The trough collector according to paragraph 43 or paragraph 44, wherein said slot traverses the entire longitudinal length of said sleeve.
         47. The trough collector according to any of paragraphs 44 to 46, wherein said sleeve comprises a removable cover positioned over said slot to retain heat within said sleeve.   48. The trough collector according to paragraph 47, wherein said cover is movable and configured to remain closed in solar energy collecting positions for the trough solar energy collector and is configured to open in a non-operational position for the solar energy collector.   49. The trough collector according to paragraph 48, further comprising a first track assembly and a second track assembly, each comprising springs engaging said movable cover.   50. The trough collector according to paragraph 49, wherein said first and second track assemblies and said sleeve are configured to rotate into all positions that said trough collector rotates.   51. The trough collector according to paragraph 49 or paragraph 50 wherein said collector tube and said movable cover have surfaces that engage one another at a position during the rotation of said trough collector.   52. The trough collector according to any of paragraphs 49 to 51, wherein said movable cover engages compressed springs in light-collecting positions of said trough collector.   53. The trough collector according to any of paragraphs 43 to 52, further comprising a reflective strip disposed between said collector tube and said sleeve; wherein said strip spans at least the majority of the longitudinal length of said sleeve.   54. The trough collector according to any of paragraphs 43 to 53, further comprising gaskets disposed around said collector tube to retain heat.   55. The trough collector according to paragraph 54, wherein said gaskets comprise silicone foam.   56. The trough collector according to any of paragraphs 1 to 55, further comprising a mount collar containing a bearing, said bearing engaging said collector tube to allow relative motion between said collector tube and said mount collar.   57. The trough collector according to paragraph 56, further comprising a plurality of fasteners engaging said mount collar to press upon the bearing, said fasteners having a range of adjustment sufficient to move said bearing and thereby align said collector tube to the focus line of said collecting panel.   58. The trough collector according to any of paragraphs 1 to 57, further comprising a stanchion containing a bearing, said bearing engaging said collector tube to allow relative motion between said collector tube and said stanchion.   59. The trough collector according to paragraph 58, further comprising a plurality of fasteners engaging said stanchion to press upon the bearing, said fasteners having a range of adjustment sufficient to move said bearing and thereby align said collector tube to the focus line of said collecting panels.   60. The trough collector according to any of paragraph 58 or paragraph 59, wherein said stanchion is mounted upon said panel-retaining strip.   61. The trough collector according to any of paragraphs 56 to 60, wherein said bearing comprises a graphite bearing.   62. The trough collector according to any of paragraphs 1 to 61, further comprising a drive system that comprises:
           a motor having a shaft;   a first sprocket attached to said support assembly; and   a second sprocket attached to said motor shaft;   wherein said first sprocket and second sprocket are coupled with a chain and are disposed substantially within the same plane.   
           63. The trough collector according to paragraph 62, wherein said chain is constantly biased to a tensioned configuration.   64. The trough collector according to paragraph 63, wherein said chain is constantly biased by a charged spring.   65. The trough collector according to any of paragraphs 62 to 64, wherein the gear ratio of said first sprocket to said second sprocket is about 10:1.   66. A linear array of trough solar energy collectors, comprising:
           a. a plurality of trough solar energy collectors according to any of paragraphs 1 to 65;   b. a motor having a shaft;   c. a first drive shaft with one end attached to said motor shaft; and   d. at least one sprocket assembly comprising a first sprocket attached to one trough collector and a second sprocket attached to said first drive shaft; wherein said first and second sprocket are coupled with a chain and disposed substantially within the same plane.   
           67. The linear array according to paragraph 66, wherein adjacent collectors are joined to one another by connecting a first longitudinal rail of a first collector to a first longitudinal rail of a second collector adjacent to said first collector.   68. The linear array according to paragraph 67, wherein each of said first longitudinal rail of said first collector and said first longitudinal rail of said second collector is end longitudinal rail disposed along a longitudinal edge of said cylindrical or parabolic surface of said collector.   69. The linear array according to paragraph 68, wherein said first collector and said second collector are joined to each other by further connecting a second longitudinal rail of said first collector to a second longitudinal rail of said second collector.   70. The linear array according to paragraph 69, wherein each of said second longitudinal rail of said first collector and said second longitudinal rail of said second collector is a rail adjacent to an end longitudinal rail disposed along a longitudinal edge of said cylindrical or parabolic surface of said collector.   71. The linear array according to any of paragraphs 66 to 70, further comprising a mount tube that engages two adjacent collectors, wherein said mount tube is supported by a stand disposed between said adjacent collectors through a bearing.   72. The linear array according to paragraph 71, wherein said mount tube is a fixedly attached to said adjacent collectors such that said mount tube and said two adjacent collectors rotate in concert.   73. The linear array according to paragraph 72, wherein said bearing comprises a graphite bearing.   74. The linear array according to any of paragraphs 66 to 73, wherein said motor is located at one end of said linear array.   75. The linear array according to any of paragraphs 66 to 73, further comprising a second drive shaft coupled to said motor shaft and the other end extending to an opposite direction from said first drive shaft.   76. The linear array according to paragraph 76, wherein said motor is disposed at the middle point of said linear array.   77. The linear array according to paragraph 75 or 76, wherein said array comprises at least ten collectors.   78. The linear array according any of paragraphs 66 to 77, wherein at least one said trough solar energy collector in said linear array has no said sprocket assembly attached to it.   79. The linear array according any of paragraphs 66 to 78, further comprising a wash system configured to wash said solar energy collectors when said collectors are not collecting solar energy.   80. The linear array according to paragraph 79, wherein said wash system comprises a plurality of nozzles controlled by at least one valve; said valve controlled by a control system.   81. The linear array according to paragraph 80, wherein said valve is solenoid valve.   82. The linear array according to paragraph 80 or 81, wherein said control system is a time-based control system.   83. The linear array according to any of paragraphs 80 to 82, wherein said control system controls rotation of said solar energy collectors.   84. A method of assembling a trough solar energy collector comprising:
           a. assembling a support assembly for supporting a plurality of solar energy collecting panels;   b. securing a plurality of solar energy collecting panels to said support assembly by a plurality of transverse panel-retaining strips;   c. securing an edge of said collecting panels to a transverse end of said support assembly with two longitudinal strips; and   d. placing a collector tube positioned to receive light reflected by said collecting panels; said collector tube being supported by a plurality of stanchions disposed upon said panel-retaining strips.   
           85. The method according to paragraph 84, wherein said two longitudinal strips are cowlings.   86. The method according to paragraph 85, wherein said two cowlings are “U”-shaped.   87. The method according to any of paragraphs 84 to 86, wherein the steps of assembling a support assembly further comprises:
           a. assembling a first and a second end assembly;   b. securing a plurality of transverse ribs to a plurality of longitudinal rails; said ribs having a shape approximating a chord or a cylindrical or parabolic surface;   c. securing said end assemblies to said longitudinal rails and to two of said plurality of ribs;   
           88. The method according to paragraph 87, wherein said end assemblies are formed by placing two identical end sections adjacent to one another but facing in opposite directions to form a triangulated structure with attached said ribs and securing each of said identical end sections to at least one of said longitudinal rails.   89. The method according to paragraph 88, wherein each said end sections further comprising two identical end plates separated by spacers and a spanning piece spanning a gap between two end plates.   90. A kit for making a support assembly for a trough solar energy collector comprising four identical end plates, a plurality of longitudinal rails having a cross-sectional shape and area, and a plurality of ribs having openings of about the cross-sectional shape and area of said plurality of longitudinal rails.   91. A kit according to paragraph 90, further comprising a plurality of cowlings configured to secure edges of a plurality of solar energy collecting panels to an assembled kit of paragraph 88.   92. A kit according to paragraph 91, further comprising at least one transverse panel-retaining strip adapted to engage adjacent solar energy collecting panels upon said support assembly.   93. A rack to assemble a trough solar energy collector according to any of paragraphs 1 to 65, comprising:
           a base having two longitudinal sides; each of said longitudinal sides having about the same length as said longitudinal rail of said trough solar energy collector, and   a plurality of brackets mounted along each of said longitudinal sides at pre-determined locations; said brackets configured to receive an end of said transverse rib of said trough solar energy collector.   
           94. The rack according to paragraph 93, wherein the positions of said brackets can be adjusted.   95. The rack according to paragraph 93 or paragraph 94, further comprising an elevated longitudinal beam configured to support an apex, minimum, or vertex of said rib.   96. The rack according to any of paragraph 93 to 95, further comprising a plurality brackets disposed at an apex, minimum, or vertex of said rib; said brackets configured to provide backing for rivets.   97. The rack according to any of paragraph 93 to 96, further comprising a strut having one end in slidable contact with said end assembly of said solar energy collector and the other end fixedly mounted on a fixed point of said rack, thereby providing lateral support to said end assembly.   98. A rack to assemble a trough solar energy collector according to any of paragraphs 1 to 65, comprising:
           a base having a hollow region; said base having sufficient surface to support four sides of said trough solar energy collector with the solar energy collecting side facing downward; and   a removable inner rack configured to place in said hollow region of said base and to support said trough solar energy collector with the solar energy collecting side facing upward;   
           99. The rack according to paragraph 98, further comprises a plurality of brackets mounted on said base.   100. A method of utilizing a trough solar energy collector according to any of paragraphs 1 to 65 to generate steam, comprising:
           a. assembling a trough solar energy collector according to any of paragraphs 1 to 65; and   b. heating water contained in said collector tube by light reflected by said solar energy collecting panels to generate steam.   
           101. A method of utilizing a trough solar energy collector according to any of paragraphs 1 to 65 to generate steam, comprising:
           a. assembling a trough solar energy collector according to any of paragraphs 1 to 65;   b. exchanging heat between a working fluid contained in said collector tube heated by light reflected by said solar energy collecting panels and water to generate steam.   
           102. A support assembly as set forth in any paragraph above.   103. A method of assembly or use as herein described.       

     Where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the inventions. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. Therefore, to the extent there are variations of the invention which are within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent that this patent will cover those variations as well. Finally, all publications and patent applications cited in this specification are herein incorporated by reference in their entirety as if each individual publication or patent application were specifically and individually put forth herein. 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Rib is 
                   
                 1- 
                 2- 
                   
                   
                   
                   
                 Transparent 
               
               
                   
                   
                 half or 
                 Ribs 
                 piece 
                 piece 
                   
                   
                 No 
                 Conventional 
                 cover 
               
               
                   
                 Rib is 
                 is about 
                 attached 
                 T or Y 
                 T or Y 
                 Stationary 
                 Rotating 
                 cover on 
                 cover on 
                 with 
               
               
                   
                 full 
                 half of 
                 to outer 
                 end- 
                 end- 
                 collector 
                 collector 
                 collector 
                 collector 
                 removable 
               
               
                   
                 parabola 
                 parabola 
                 skin 
                 section 
                 section 
                 pipe 
                 pipe 
                 pipe 
                 pipe 
                 cover 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 X 
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 2 
                   
                 X 
               
               
                 3 
                   
                   
                 X 
               
               
                 4 
                   
                   
                   
                 X 
               
               
                 5 
                   
                   
                   
                   
                 X 
               
               
                 6 
                   
                   
                   
                   
                   
                 X 
               
               
                 7 
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 8 
                   
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 9 
                   
                   
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 10 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 11 
                 X 
                   
                 X 
               
               
                 12 
                 X 
                   
                   
                 X 
               
               
                 13 
                 X 
                   
                   
                   
                 X 
               
               
                 14 
                 X 
                   
                   
                   
                   
                 X 
               
               
                 15 
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 16 
                 X 
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 17 
                 X 
                   
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 18 
                 X 
                   
                   
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 19 
                 X 
                   
                 X 
                 X 
               
               
                 20 
                 X 
                   
                 X 
                   
                 X 
               
               
                 21 
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 22 
                 X 
                   
                 X 
                   
                   
                   
                 X 
               
               
                 23 
                 X 
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 24 
                 X 
                   
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 25 
                 X 
                   
                 X 
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 26 
                 X 
                   
                   
                 X 
                   
                 X 
               
               
                 27 
                 X 
                   
                   
                 X 
                   
                   
                 X 
               
               
                 28 
                 X 
                   
                   
                 X 
                   
                   
                   
                 X 
               
               
                 29 
                 X 
                   
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 30 
                 X 
                   
                   
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 31 
                 X 
                   
                   
                   
                 X 
                 X 
               
               
                 32 
                 X 
                   
                   
                   
                 X 
                   
                 X 
               
               
                 33 
                 X 
                   
                   
                   
                 X 
                   
                   
                 X 
               
               
                 34 
                 X 
                   
                   
                   
                 X 
                   
                   
                   
                 X 
               
               
                 35 
                 X 
                   
                   
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 36 
                 X 
                   
                   
                   
                   
                 X 
                   
                 X 
               
               
                 37 
                 X 
                   
                   
                   
                   
                 X 
                   
                   
                 X 
               
               
                 38 
                 X 
                   
                   
                   
                   
                 X 
                   
                   
                   
                 X 
               
               
                 39 
                 X 
                   
                   
                   
                   
                   
                 X 
                 X 
               
               
                 40 
                 X 
                   
                   
                   
                   
                   
                 X 
                   
                 X 
               
               
                 41 
                 X 
                   
                   
                   
                   
                   
                 X 
                   
                   
                 X 
               
               
                 42 
                 X 
                   
                 X 
                 X 
                   
                 X 
               
               
                 43 
                 X 
                   
                 X 
                 X 
                   
                   
                 X 
               
               
                 44 
                 X 
                   
                 X 
                 X 
                   
                   
                   
                 X 
               
               
                 45 
                 X 
                   
                 X 
                 X 
                   
                   
                   
                   
                 X 
               
               
                 46 
                 X 
                   
                 X 
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 47 
                 X 
                   
                 X 
                   
                 X 
                 X 
               
               
                 48 
                 X 
                   
                 X 
                   
                 X 
                   
                 X 
               
               
                 49 
                 X 
                   
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 50 
                 X 
                   
                 X 
                   
                 X 
                   
                   
                   
                 X 
               
               
                 51 
                 X 
                   
                 X 
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 52 
                 X 
                   
                 X 
                 X 
                   
                 X 
                   
                 X 
               
               
                 53 
                 X 
                   
                 X 
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 54 
                 X 
                   
                 X 
                 X 
                   
                 X 
                   
                   
                   
                 X 
               
               
                 55 
                 X 
                   
                 X 
                 X 
                   
                   
                 X 
                 X 
               
               
                 56 
                 X 
                   
                 X 
                 X 
                   
                   
                 X 
                   
                 X 
               
               
                 57 
                 X 
                   
                 X 
                 X 
                   
                   
                 X 
                   
                   
                 X 
               
               
                 58 
                 X 
                   
                 X 
                   
                 X 
                 X 
                   
                 X 
               
               
                 59 
                 X 
                   
                 X 
                   
                 X 
                 X 
                   
                   
                 X 
               
               
                 60 
                 X 
                   
                 X 
                   
                 X 
                 X 
                   
                   
                   
                 X 
               
               
                 61 
                 X 
                   
                 X 
                   
                 X 
                   
                 X 
                 X 
               
               
                 62 
                 X 
                   
                 X 
                   
                 X 
                   
                 X 
                   
                 X 
               
               
                 63 
                 X 
                   
                 X 
                   
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 64 
                   
                 X 
                 X 
               
               
                 65 
                   
                 X 
                   
                 X 
               
               
                 66 
                   
                 X 
                   
                   
                 X 
               
               
                 67 
                   
                 X 
                   
                   
                   
                 X 
               
               
                 68 
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 69 
                   
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 70 
                   
                 X 
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 71 
                   
                 X 
                   
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 72 
                   
                 X 
                 X 
                 X 
               
               
                 73 
                   
                 X 
                 X 
                   
                 X 
               
               
                 74 
                   
                 X 
                 X 
                   
                   
                 X 
               
               
                 75 
                   
                 X 
                 X 
                   
                   
                   
                 X 
               
               
                 76 
                   
                 X 
                 X 
                   
                   
                   
                   
                 X 
               
               
                 77 
                   
                 X 
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 78 
                   
                 X 
                 X 
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 79 
                   
                 X 
                   
                 X 
                   
                 X 
               
               
                 80 
                   
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 81 
                   
                 X 
                   
                 X 
                   
                   
                   
                 X 
               
               
                 82 
                   
                 X 
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 83 
                   
                 X 
                   
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 84 
                   
                 X 
                   
                   
                 X 
                 X 
               
               
                 85 
                   
                 X 
                   
                   
                 X 
                   
                 X 
               
               
                 86 
                   
                 X 
                   
                   
                 X 
                   
                   
                 X 
               
               
                 87 
                   
                 X 
                   
                   
                 X 
                   
                   
                   
                 X 
               
               
                 88 
                   
                 X 
                   
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 89 
                   
                 X 
                   
                   
                   
                 X 
                   
                 X 
               
               
                 90 
                   
                 X 
                   
                   
                   
                 X 
                   
                   
                 X 
               
               
                 91 
                   
                 X 
                   
                   
                   
                 X 
                   
                   
                   
                 X 
               
               
                 92 
                   
                 X 
                   
                   
                   
                   
                 X 
                 X 
               
               
                 93 
                   
                 X 
                   
                   
                   
                   
                 X 
                   
                 X 
               
               
                 94 
                   
                 X 
                   
                   
                   
                   
                 X 
                   
                   
                 X 
               
               
                 95 
                   
                 X 
                 X 
                 X 
                   
                 X 
               
               
                 96 
                   
                 X 
                 X 
                 X 
                   
                   
                 X 
               
               
                 97 
                   
                 X 
                 X 
                 X 
                   
                   
                   
                 X 
               
               
                 98 
                   
                 X 
                 X 
                 X 
                   
                   
                   
                   
                 X 
               
               
                 99 
                   
                 X 
                 X 
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 100 
                   
                 X 
                 X 
                   
                 X 
                 X 
               
               
                 101 
                   
                 X 
                 X 
                   
                 X 
                   
                 X 
               
               
                 102 
                   
                 X 
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 103 
                   
                 X 
                 X 
                   
                 X 
                   
                   
                   
                 X 
               
               
                 104 
                   
                 X 
                 X 
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 105 
                   
                 X 
                 X 
                 X 
                   
                 X 
                   
                 X 
               
               
                 106 
                   
                 X 
                 X 
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 107 
                   
                 X 
                 X 
                 X 
                   
                 X 
                   
                   
                   
                 X 
               
               
                 108 
                   
                 X 
                 X 
                 X 
                   
                   
                 X 
                 X 
               
               
                 109 
                   
                 X 
                 X 
                 X 
                   
                   
                 X 
                   
                 X 
               
               
                 110 
                   
                 X 
                 X 
                 X 
                   
                   
                 X 
                   
                   
                 X 
               
               
                 111 
                   
                 X 
                 X 
                   
                 X 
                 X 
                   
                 X 
               
               
                 112 
                   
                 X 
                 X 
                   
                 X 
                 X 
                   
                   
                 X 
               
               
                 113 
                   
                 X 
                 X 
                   
                 X 
                 X 
                   
                   
                   
                 X 
               
               
                 114 
                   
                 X 
                 X 
                   
                 X 
                   
                 X 
                 X 
               
               
                 115 
                   
                 X 
                 X 
                   
                 X 
                   
                 X 
                   
                 X 
               
               
                 116 
                   
                 X 
                 X 
                   
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 117 
                   
                   
                 X 
                 X 
               
               
                 118 
                   
                   
                 X 
                   
                 X 
               
               
                 119 
                   
                   
                 X 
                   
                   
                 X 
               
               
                 120 
                   
                   
                 X 
                   
                   
                   
                 X 
               
               
                 121 
                   
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 122 
                   
                   
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 123 
                   
                   
                 X 
                   
                   
                   
                   
                   
                   
                 X 
               
               
                 124 
                   
                   
                 X 
                 X 
                   
                 X 
               
               
                 125 
                   
                   
                 X 
                 X 
                   
                   
                 X 
               
               
                 126 
                   
                   
                 X 
                 X 
                   
                   
                   
                 X 
               
               
                 127 
                   
                   
                 X 
                 X 
                   
                   
                   
                   
                 X 
               
               
                 128 
                   
                   
                 X 
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 129 
                   
                   
                 X 
                   
                 X 
                 X 
               
               
                 130 
                   
                   
                 X 
                   
                 X 
                   
                 X 
               
               
                 131 
                   
                   
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 132 
                   
                   
                 X 
                   
                 X 
                   
                   
                   
                 X 
               
               
                 133 
                   
                   
                 X 
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 134 
                   
                   
                 X 
                   
                   
                 X 
                   
                 X 
               
               
                 135 
                   
                   
                 X 
                   
                   
                 X 
                   
                   
                 X 
               
               
                 136 
                   
                   
                 X 
                   
                   
                 X 
                   
                   
                   
                 X 
               
               
                 137 
                   
                   
                 X 
                   
                   
                   
                 X 
                 X 
               
               
                 138 
                   
                   
                 X 
                   
                   
                   
                 X 
                   
                 X 
               
               
                 139 
                   
                   
                 X 
                   
                   
                   
                 X 
                   
                   
                 X 
               
               
                 140 
                   
                   
                 X 
                 X 
                   
                 X 
                   
                 X 
               
               
                 141 
                   
                   
                 X 
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 142 
                   
                   
                 X 
                 X 
                   
                 X 
                   
                   
                   
                 X 
               
               
                 143 
                   
                   
                 X 
                   
                 X 
                 X 
                   
                 X 
               
               
                 144 
                   
                   
                 X 
                   
                 X 
                 X 
                   
                   
                 X 
               
               
                 145 
                   
                   
                 X 
                   
                 X 
                 X 
                   
                   
                   
                 X 
               
               
                 146 
                   
                   
                 X 
                 X 
                   
                   
                 X 
                 X 
               
               
                 147 
                   
                   
                 X 
                 X 
                   
                   
                 X 
                   
                 X 
               
               
                 148 
                   
                   
                 X 
                 X 
                   
                   
                 X 
                   
                   
                 X 
               
               
                 149 
                   
                   
                 X 
                   
                 X 
                   
                 X 
                 X 
               
               
                 150 
                   
                   
                 X 
                   
                 X 
                   
                 X 
                   
                 X 
               
               
                 151 
                   
                   
                 X 
                   
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 152 
                   
                   
                   
                 X 
                   
                 X 
               
               
                 153 
                   
                   
                   
                 X 
                   
                   
                 X 
               
               
                 154 
                   
                   
                   
                 X 
                   
                   
                   
                 X 
               
               
                 155 
                   
                   
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 156 
                   
                   
                   
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 157 
                   
                   
                   
                   
                 X 
                 X 
               
               
                 158 
                   
                   
                   
                   
                 X 
                   
                 X 
               
               
                 159 
                   
                   
                   
                   
                 X 
                   
                   
                 X 
               
               
                 160 
                   
                   
                   
                   
                 X 
                   
                   
                   
                 X 
               
               
                 161 
                   
                   
                   
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 162 
                   
                   
                   
                 X 
                   
                 X 
                   
                 X 
               
               
                 163 
                   
                   
                   
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 164 
                   
                   
                   
                 X 
                   
                 X 
                   
                   
                   
                 X 
               
               
                 165 
                   
                   
                   
                 X 
                   
                   
                 X 
                 X 
               
               
                 166 
                   
                   
                   
                 X 
                   
                   
                 X 
                   
                 X 
               
               
                 167 
                   
                   
                   
                 X 
                   
                   
                 X 
                   
                   
                 X 
               
               
                 168 
                   
                   
                   
                   
                 X 
                 X 
                   
                 X 
               
               
                 169 
                   
                   
                   
                   
                 X 
                 X 
                   
                   
                 X 
               
               
                 170 
                   
                   
                   
                   
                 X 
                 X 
                   
                   
                   
                 X 
               
               
                 171 
                   
                   
                   
                   
                 X 
                   
                 X 
                 X 
               
               
                 172 
                   
                   
                   
                   
                 X 
                   
                 X 
                   
                 X 
               
               
                 173 
                   
                   
                   
                   
                 X 
                   
                 X 
                   
                   
                 X 
               
               
                 174 
                   
                   
                   
                   
                   
                 X 
                   
                 X 
               
               
                 175 
                   
                   
                   
                   
                   
                 X 
                   
                   
                 X 
               
               
                 176 
                   
                   
                   
                   
                   
                 X 
                   
                   
                   
                 X 
               
               
                 177 
                   
                   
                   
                   
                   
                   
                 X 
                 X 
               
               
                 178 
                   
                   
                   
                   
                   
                   
                 X 
                   
                 X 
               
               
                 179 
                   
                   
                   
                   
                   
                   
                 X 
                   
                   
                 X