Abstract:
A solar energy collection assembly includes a wind deflector and a solar module. A method of assembling includes roll forming frame sections of channel from sheet metal, connecting the frame sections to form an upright frame, and attaching the wind deflector and solar module to the frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of pending U.S. patent application Ser. No. 12/367,977, filed Feb. 9, 2009, which claims priority to U.S. Provisional Patent Application No. 61/049,567, filed May 1, 2008. The entire disclosure of both applications is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     Embodiments of the present invention relate to a rack assembly for mounting solar energy collecting modules and an associated method for constructing a rack assembly. 
     DESCRIPTION OF RELATED ART 
     Photovoltaics (PV) is the field of technology and research related to the application of solar cells for energy by converting sunlight directly into electricity. Due to the growing demand for clean sources of energy, the manufacture of solar cells and PV arrays has expanded dramatically in recent years. These mechanisms may be may be ground-mounted or built into the roof or walls of a building. Financial incentives, such as preferential feed-in tariffs for solar-generated electricity, and net metering, have supported solar PV installations in many countries. 
     A variety of solar energy collecting modules currently exist. One such module is a PV panel which converts solar energy into electricity. Another module is a solar thermal collector which harnesses solar energy for heat. The modules can have different geometries, but are commonly made with a generally flat construction. PV panels are often electrically connected in multiples as solar photovoltaic arrays to convert energy from the sun into electricity. In operation, photons from sunlight knock electrons into a higher state of energy, creating electricity. Solar cells produce direct current electricity from light, which can be used for such tasks as powering equipment or recharging a battery. Cells require protection from the environment and are packaged usually behind a glass sheet. When more power is required than a single cell can deliver, cells are electrically connected together to form PV modules, or solar panels. 
     Multiple issues have prevented the growth of solar energy from becoming even more explosive. The most pervasive of these issues may be installation and material costs. However, due to economies of scale, solar panels become less expensive as people use and buy more and as manufacturers increase production to meet demand. Thus, the cost and price is expected to drop in the years to come. 
     Solar energy collecting modules are currently used in a variety of settings, including commercial, residential, and industrial environments. These modules are typically mounted on a structure secured to a support surface, such as a rooftop. Different considerations affect the design and construction of the mounting structures for the modules. These factors include ease of manufacture and installation, minimization of related costs, and resistance to environmental factors such as wind forces. 
     Various problems have hindered the use and development of existing mounting structures. For example, because of lift forces created by wind gusts, existing mounting structures have often generated inadequate frictional forces to maintain satisfactory contact with the underlying support surface. Despite efforts made to reduce mounting structure surface area to create a mounting structure that minimizes lift forces created by the wind, it has often been viewed as necessary to secure the mounting structures to the rooftop or other base supporting surface. This attachment process often proves to be harmful and destructive to the underlying supporting surface. For example, the installer may be required to penetrate the roof shingles, roofing paper, and sheathing. This penetration makes the roof less weather resistant and thus may result in damage to the building itself. 
     Additionally, materials for the mounting structures are often expensive and manufacturing and installation have been complicated, thus adding to the expense of the mounting structure. An increase to the cost of the system negatively impacts the financial advantage that consumers expect from a solar energy solution. 
     Generally, solving any one of the aforementioned problems has magnified the other existing problems and no suitable solution has been found for a secure mounting structure having a reasonable cost. 
     Accordingly, a practical solution is needed that provides a secure mounting rack assembly with a novel construction for mounting solar energy collecting modules. Additionally, a solution is needed for providing an efficient and inexpensive method of constructing the novel rack assemblies. 
     SUMMARY OF THE EMBODIMENTS 
     In a first aspect, an embodiment comprises a rack assembly for supporting a solar energy collecting module on a support surface. The rack assembly comprises a plurality of upright frames and a transverse element connected to the plurality of frames. Each frame comprises a first base leg extending substantially parallel to the support surface in a first direction and a second leg extending from the first leg at an angle relative to the first leg. The second leg supports the solar energy collecting module at an angle relative to the support surface. A transverse member is connected to the first leg of each of the plurality of frames and extends substantially parallel to the support surface in a second direction substantially perpendicular to the first direction. The plurality of upright frames is constructed by roll forming at least one leg of the upright frame from sheet metal. 
     In a further aspect, an embodiment comprises a rack assembly for supporting a solar energy collecting module on a support surface. The rack assembly comprises a plurality of upright triangular frames. Each triangular frame comprises a first leg extending substantially parallel to the support surface in a first direction and a second leg extending from the first leg at a first angle relative to the first leg. The second leg supports the solar energy collecting module at an angle relative to the support surface. Each frame additionally includes a third leg extending from the first leg at a second angle relative to the first leg, the third leg supporting a wind deflector plate at an angle relative to the support surface, the third leg connected with the second leg to form the triangular frame. Each frame further includes a transverse member connected to the first leg of each of the plurality of frames and extending substantially parallel to the support surface in a second direction. 
     In another aspect, an embodiment comprises a method for constructing a rack assembly for supporting a solar energy collecting module on a support surface. The method comprises roll forming a first and second section of channel from sheet metal. The first and second sections of channel are connected to form an upright frame. A transverse element is attached to the upright frame. The upright frame comprises a first leg formed from the first section of channel and extending substantially parallel to the support surface. The upright frame also comprises a second leg formed from the second section of channel and extending from the first leg at an angle relative to the first leg. 
     In an additional aspect, an embodiment comprises a method for on-site construction of a rack assembly for supporting a solar energy collecting module on a support surface. The method comprises providing for a roll forming machine and a coil of sheet metal adjacent an installation location, using the roll forming machine to form a plurality of channels from the coil of sheet metal, and constructing an upright frame from the channels. The frame comprises a horizontally extending leg, a first upwardly angled leg, and a second upwardly angled leg. A transverse element is connected to a plurality of upright frames. 
     Other objects, features, and characteristics of the present embodiments will become apparent upon consideration of the following description and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In the drawings, like reference characters generally refer to the same parts throughout the different views. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which: 
         FIG. 1  is a front perspective view of a rack assembly according to a first embodiment. 
         FIG. 2  is a rear perspective view of a rack assembly according to the first embodiment. 
         FIG. 3  is a side view of a rack assembly in accordance with an additional embodiment of the invention. 
         FIG. 4  is a perspective view of a clip for use with multiple embodiments of the invention. 
         FIG. 5  is a perspective view of a rack assembly according to a further embodiment of the invention. 
         FIG. 6  is a top plan schematic view of a rack assembly array in accordance with an additional embodiment of the invention. 
         FIG. 7  is a perspective view illustrating an alternative rack assembly embodiment. 
         FIG. 8  is a perspective view illustrating a pop-rivet attachment of a stiffening rib to a frame in accordance with the alternative embodiment of the invention. 
         FIG. 9  is a perspective view illustrating laminates attached to the stiffening ribs in accordance with the alternative embodiment of the invention. 
         FIG. 10  is a perspective view illustrating a junction between the laminate, the stiffening rib, and the rack assembly in accordance with the alternative embodiment of the invention. 
         FIG. 11  is a side view illustrating an additional embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a first embodiment of a rack assembly  100 . The rack assembly  100  may include a plurality of frames  104 . Each frame  104  may include a base leg  112  and one or more additional legs  114  and  116 . The rack assembly may additionally include clips  106  and panels  122  having flanges  108 . A transverse member  110  may extend the length of the rack assembly  100  and friction pads  130  may be affixed to the base of the rack assembly  100 . 
     In the illustrated embodiment, two solar energy collecting modules  102  are mounted on three frames  104 . The solar energy collecting modules  102  are of the kind that is generally flat, such as photovoltaic modules. The solar energy collecting modules  102  are mounted on the rack assembly  100  at a predetermined angle and are secured by clips  106  and flange portions  108  of panels  122 . The transverse member  110  extends the length of the rack assembly  100  and is secured to the frames  104  on the base leg  112  of each of the frames  104 . The transverse member  110  may serve as a ballast tray for adding additional weight to the rack assembly  100 . 
     The rack assembly  100  may be mounted on relatively leveled and mildly sloping surfaces, such as for example on the roof of a building. The friction pads  130  affixed to the bottom of the frames  104  may provide additional support for retaining the rack assembly  100  on a support surface. The friction pads  130  may be made of rubber and may be affixed in a variety of configurations using one of a variety of techniques. In the illustrated embodiment, one friction pad  130  is juxtaposed adjacent each end of the base leg  112  of the frame  104 . However, it should be understand that one friction pad  130  or a larger number of friction pads  130  may be affixed in alternative configurations. 
       FIG. 2  illustrates the rack assembly  100  as shown in  FIG. 1  from a rear perspective view. As can be seen more clearly, two panels  122  extend the width of the rack assembly  100 . The panels  122  are dimensioned to serve as wind deflectors to eliminate uplift forces. Each panel  122  spans the distance between two frames  104 , which corresponds approximately to the width of each solar energy collecting module  102 . 
     Longer panels that span the full width of the rack assembly  100  may also be used. The panels  122  may be secured to the frames  104  using any appropriate fastening method, such as adhesive, screws, bolts, or pop rivets. As set forth above, with respect to  FIG. 1 , the panels  122  include flange portion  108  which serves to retain the top edges of each solar energy collecting module  102 . 
       FIG. 3  is a side view of a rack assembly  300 . The frame  304  shown in this embodiment has a triangular shape. The frame  304  includes a base leg  312  and two angled legs  314 ,  316 . Each leg  312 ,  314 ,  316  is preferably comprised of U-shaped channel pieces. The U-shaped channel pieces may be easily manufactured from roll-formed sheet metal, as will be described in more detail below. The legs  312 ,  314 , and  316  may be juxtaposed at pre-selected angles  324 ,  326 , and  328 . 
     Other frame geometries may also be used. Frames may have less than three legs or more than three legs. Frames may have closed geometries, such as a triangle or square, or open geometries, such as an open angle formed by two legs. 
     Using a triangle frame embodiment as illustrated in  FIG. 3 , the base leg  312  rests on a support surface. One or more frictional pads  330  may be affixed to a portion of the base leg  312  that contacts the support surface. In the embodiment of  FIG. 3 , the first angled leg  314  supports the solar energy collecting module  302 , and the second angled leg  316  supports a panel  322 . 
     The incline angle  324  of first angled leg  314  may be predetermined in order to maximize the interception of solar energy. Similarly, the incline angle  328  between the first  314  and second  316  angled legs may be predetermined to utilize the wind deflecting properties of the panels  322  and to control the amount of uplift generated by wind passing over the rack assembly  300 . The incline angles  324 ,  326 , and  328  of the first angled leg  314  and the second angled leg  316  may be adjusted by varying the lengths of the first and second angled legs  314 ,  316 . Additionally, one or more transverse members  310  may be connected to the base leg  312  of the frame  304 . The transverse member  310  may be used as a ballast tray. 
       FIG. 4  illustrates a clip  406  used to secure the bottom edge of solar energy collecting modules  402 . The height of the clip  406  may be selected to approximately equal the height of the solar energy collecting module  402  such that the solar energy collecting module  402  can be firmly and securely inserted into the clip  406 . The clip  406  may be manufactured separately from the frame  404  of the rack assembly  400  and secured onto the frame  404  using fasteners such as screws, bolts, or pop rivets. The clip  406  may alternatively be made by punching out and bending a piece of the frame  404 . A tab  452  maybe used to separate and longitudinally align adjacent solar energy collecting modules  402 . 
       FIG. 5  illustrates an additional embodiment of a rack assembly  500  in which seventeen frames  504  support sixteen solar energy collecting modules  502 . The embodiments shown in  FIGS. 1-5  are exemplary only and rack assemblies with different numbers of frames may be constructed to hold different numbers of solar energy collecting modules depending on need. Longer rack assemblies may require multiple pieces of transverse member  510  in order to connect all the frames. 
       FIG. 6  is a top plan schematic view of a rack assembly array  600 . As shown in  FIG. 6 , rack assemblies  610  are combined to form a rack assembly array  600 . Although shown with three rack assemblies  610 , a rack assembly array may include more or fewer rack assemblies. Additionally, the rack assemblies do not need to be of the same size. Rows of rack assemblies  610  may be connected to adjacent rows with sections of galvanized steel strut  602 . The steel strut  602  ties the sections of rack assemblies  610  together to spread force loads and may additionally be used as mounting points to which electrical conduit runs can be affixed. 
       FIG. 7  is a perspective view illustrating an alternative rack assembly embodiment. A rack assembly  700  includes a frame  704  for use with a solar energy collecting module in the form of an unframed PV laminate. The frame  704  may have a triangular configuration including a base member  712  connected with angled members  714  and  716 . One or more stiffening ribs  740  may be provided and may be connected to angled members  714  of multiple frames  704 . the connection may be facilitated through the use of pop-rivets or other fasteners. The rack assembly  700  may also include one or more transverse members ( 1110 ,  FIG. 11 ), which may serve as ballast trays. 
     In order to mount PV laminates, an adhesive or other fastening means may be applied to affix the PV laminates to the stiffening ribs  740 . In addition to supporting the PV laminates, the stiffening ribs  740  may function as a bonded grounding path for the assembly  700 . 
     Similarly to the embodiments described above with respect to  FIGS. 1-5 , the rack assembly  700  may be constructed from galvanized sheet metal members assembled with pop-rivets or other fasteners. 
       FIG. 8  is a perspective view illustrating a pop-rivet attachment  842  of a stiffening rib  840  to a frame  804  in accordance with the alternative embodiment of  FIG. 7 . More specifically, the stiffening rib  840  is attached by the pop-rivet attachment  842  to angled arm  814  of the frame  804 . In the illustrated embodiment, a flange  808  may provide additional stability. 
       FIG. 9  is a perspective view illustrating PV laminates  950  attached to a plurality of stiffening ribs  940  in accordance with an embodiment of the invention. Such attachment is preferably accomplished through the use of an adhesive, but may alternatively be accomplished through other fastening mechanisms. Flange portions  908  of panels  922  may operate to encase edges of the PV laminates  950 . In the illustrated embodiment, two PV laminates  950  are mounted on three stiffening ribs  940 . However, it should be understood that in alternative embodiments, any suitable number of stiffening ribs  940  may be implemented for attachment to the PV laminates  950 . 
       FIG. 10  is a perspective view illustrating a junction between PV laminates  1050 , a stiffening rib  1040 , and a rack assembly  1004  in accordance with the embodiment of the invention illustrated in  FIGS. 7-9 .  FIG. 10  additionally illustrates a pop-rivet connector  1042  securing the stiffening rib  1040  to the rack assembly  1004 . Additionally, panels  1022  may include flanges  1008  that cover an edge of the stiffening rib  1040  and further encase an edge of the PV laminates  1050 . 
       FIG. 11  is a side view illustrating an additional embodiment of the invention. In this embodiment, one or more transverse ribs  1140  are attached to angled arm  1114  by pop-rivet attachment  1142 . One or more stiffening ribs  1144  are separately attached to a PV laminate  1150 , preferably using adhesive  1146 . The shapes of the transverse ribs  1140  and stiffening ribs  1144  are complementary, such that the PV laminate  1150  may be attached to the rack assembly  1100  by inserting the stiffening ribs  1144  into the transverse ribs  1140 . The two complementary ribs may be secured together using locking tabs, adhesive, fasteners, such as pop-rivets or screws, or other appropriate means. In this manner, the rack assembly  1100  may be assembled at the job site, and the stiffening ribs  1144  may be adhered to the PV laminate  1150  at another location in a controlled environment in order to minimize temperature or moisture concerns. The assembly of PV laminate  1150  and stiffening ribs  1144  may then be transported to the job site and snapped onto the transverse ribs  1140  previously mounted to the rack assembly  1100 . 
     The rack assembly according to the described embodiments has a relatively simple construction, which may be easily manufactured. Referring to  FIG. 1 , the frames  104  of rack assembly  100  may be constructed using channel pieces fabricated from a roll forming process. Roll forming is a continuous bending operation in which a long strip of is passed through consecutive sets of rolls, or stands, each performing only an incremental part of a bend, until a desired cross-sectional profile is obtained. A variety of cross-sectional profiles can be produced using varied roll tools. Roll formed sections are generally lighter and stronger than extrusions of a similar shapes, as they have been work hardened in a cold state. Other advantages of roll forming include the fact that that roll formed parts can be made having a finish or already painted. Furthermore, in comparison to extrusion processes, labor for roll forming is greatly reduced. 
     Roll forming lines can be set up with multiple configurations to punch and cut off parts in a continuous operation. For cutting a part to length, the lines can be set up to use a pre-cut die where a single blank runs through the roll mill, or a post-cut die where the profile is cutoff after the roll forming process. Features may be added in a hole, notch, embossment, or shear form by punching in a roll forming line. These part features can be done in a pre-punch application before roll forming starts, in a mid-line punching application during roll forming, or a post punching application after roll forming is completed. Some roll forming lines incorporate only one of the above punch or cutoff applications, others incorporate some or all of the applications in one line. 
     A roll forming process for forming the channel pieces used in the frames of disclosed embodiments may include feeding sheet metal from a coil through a plurality of roll pass combinations in a roll pass machine. The sheet metal may be galvanized steel, Galvalume™ or any other appropriate sheet metal. In accordance with the embodiments displayed in  FIGS. 1-10 , the resulting channel pieces may have a substantially V-shape with a flat bottom wall and a pair of opposed upstanding side walls. The roll pass machine may include flying punches to form cut-outs and sheering devices to cut the channel into pieces of predetermine lengths. Once formed, the channel pieces are connected together using fasteners to form frames. Three channel pieces of different lengths may be fastened together into a triangular shape having a base leg and two angled legs. 
     Another manufacturing embodiment includes forming each of the frames from a single channel piece. Instead of roll forming each leg as a separate piece of channel, the roll pass machine may be used to form a single channel long enough to form a full frame. Notches may be formed in the sidewalls of the channel to facilitate bending the single channel piece into the frame shape. The roll pass machine may use one or more flying punches to cut the notches during the roll forming process, or, as set forth above, the notches may be cut independently before or after the channel is formed. The notched piece of channel can then be folded into a frame and fastened together using fasteners. 
     Following the formation of frames, a transverse member (such as member  110  shown in  FIG. 1 ) is fastened to a predetermined number of frames to form a rack assembly. A single transverse member may be used to span the full width of the rack assembly or multiple transverse members may be used to span the full width. The transverse element may also be formed using a roll forming process. 
     Referring to  FIG. 4 , clip  406  may be formed from cut or stamped sheet metal patterns. A first bend is used to form the top of the clip and a second bend is used to form the bottom of the clip that is fastened to the frame. A clip may also be made during the roll forming process of the channels. A flying punch may form a cutout portion in a channel which may then be bent to form the clip. 
     Referring to  FIGS. 1 and 2 , panel  122  may be formed from cut or stamped sheet metal patterns. A first bend may be used to form the flange portion  108 . The panel may be secured to the rack assembly  104  after the solar energy collecting module  102  is placed on the assembly and into the clips  106  so that the flange portion  108  retains the top edge of the solar energy collecting module  102 . 
     Furthermore, with respect to the embodiment of  FIGS. 7-11 , PV laminates  750  are attached to the stiffening ribs  740  by means of an adhesive. Adhesion of the sheet metal stiffening ribs  740  to the backside of the laminate  740  is preferably accomplished in a controlled environment in order to minimize temperature or moisture concerns. Attachment of the stiffening ribs  740  to the triangular base structures  704  is preferably accomplished by implementing a pneumatic pop-rivet gun. This can be accomplished at the job site. 
     The ease of manufacture allows for construction of a rack assembly on-site at an installation location. A portable roll forming machine may be brought to an installation location where the channels for the frame and transverse members may be fabricated. The channels may then be fastened together to form the frames and the transverse member fastened to the frames to form a rack array. For a rooftop installation, the channels and transverse member may be formed on the ground and then lifted up to the roof where the frames and rack array are formed. A conveyor belt may be used to lift the rack array elements to the roof. 
     Having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. The described embodiments are to be considered in all respects as only illustrative and not restrictive.