Abstract:
A transportable photovoltaic system includes a plurality of photovoltaic devices, a composite frame to which the plurality of photovoltaic devices are affixed, and a base structure to which the composite frame is movably attached through at least one variable-angle mount structure. The orientation of the frame and the light concentrating elements relative to the base structure can be altered employing the at least one variable-angle mount structure. The frame and the plurality of photovoltaic devices can be assembled prior to shipping, and the base structure can be manufactured on site. The transportable photovoltaic system is not affixed to ground or other fixture, but can be picked up at any time during the operational lifetime. The transportable photovoltaic system can be rapidly deployed with little or no site preparation requirement other than generally level ground, and can be retracted to a lower exposure position to avoid storm and/or hazardous conditions.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/365,301, filed Feb. 3, 2012 the entire content and disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates to solar concentrators, and more particularly to a transportable photovoltaic system configured for rapid deployment and methods of operating the same. 
         [0003]    Solar concentrators allow replacement of large quantities of expensive semiconductor materials used in fixed flat panel systems with less expensive materials so that light can be concentrated on a smaller high power semiconductor photovoltaic device to achieve comparable performance at a lower cost. Varieties of solar concentrator photovoltaic systems have been constructed and deployed that range from small rooftop systems producing a few watts to very large concentrators producing thousands of watts of power. 
         [0004]    Once deployed, the solar concentrator photovoltaic systems must tolerate exposure to temperature extremes, dust, rain, hail and high winds. The ability to tolerate gusts of 140 miles per hour is a common requirement. Power inversion from direct current (DC) to alternating current (AC) is typically performed by connecting many concentrators systems into a single inverter operating at up to many thousands of watts. In more recent embodiments, micro inverters have been introduced that will grid couple smaller solar collectors operating at powers of 100 W to 500 W. 
         [0005]    A significant cost component in many current systems is the cost for on site assembly and extensive site preparation. Concentrator systems are constructed in component form and shipped to the site for assembly. On site preparation includes grading, excavation and pouring of foundations. Once a solar concentrator photovoltaic system is constructed at a location, the solar concentrator photovoltaic system remains at that location throughout the duration of the lifetime of the solar concentrator photovoltaic system. 
       SUMMARY 
       [0006]    A transportable photovoltaic system includes a plurality of photovoltaic devices, a composite frame to which the plurality of photovoltaic devices are affixed, and a base structure to which the composite frame is movably attached through at least one variable-angle mount structure. The orientation of the frame and the light concentrating elements relative to the base structure can be altered employing the at least one variable-angle mount structure. The frame and the plurality of photovoltaic devices can be assembled prior to shipping, and the base structure can be manufactured on site. The transportable photovoltaic system is not affixed to ground or other fixture, but can be picked up at any time during the operational lifetime. The transportable photovoltaic system can be rapidly deployed with little or no site preparation requirement other than generally level ground, and can be retracted to a lower exposure position to avoid storm and/or hazardous conditions. Further, the transportable photovoltaic system can be manufactured at a low cost, and can be configured for shipment in standard shipping containers for rapid and economical transportation. 
         [0007]    According to an aspect of the present disclosure, a method of operating a plurality of photovoltaic devices is provided. The method includes: mounting a plurality of photovoltaic devices to a frame; forming an assembly by attaching the frame to a base unit through at least one variable-angle mount structure, wherein the variable-angle mount structure is configured to rotate the frame around at least one axis; and placing the base unit on a horizontal surface without affixing the base unit to the horizontal surface at a location. 
         [0008]    According to another aspect of the present disclosure, a transportable photovoltaic structure is provided, which includes an assembly of: a plurality of photovoltaic devices mounted to a frame; and a base unit attached to the frame through at least one variable-angle mount structure, wherein the variable-angle mount structure is configured to rotate the frame around at least one axis, and the base unit is configured to be placed on a horizontal surface without being affixed to the horizontal surface. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         [0009]      FIG. 1A  is a top-down view of a first exemplary solar concentrator photovoltaic assembly in a retracted position according to an embodiment of the present disclosure. 
           [0010]      FIG. 1B  is a side view of the first exemplary solar concentrator photovoltaic assembly in the retracted position according to an embodiment of the present disclosure. 
           [0011]      FIG. 1C  is a vertical cross-sectional view of the first exemplary solar concentrator photovoltaic assembly in the retracted position along the plane C-C′ in  FIG. 1A  according to an embodiment of the present disclosure. 
           [0012]      FIG. 1D  is a front view of the first exemplary solar concentrator photovoltaic assembly in the retracted position according to an embodiment of the present disclosure. 
           [0013]      FIG. 1E  is a side view of the first exemplary solar concentrator photovoltaic assembly in a tilted position according to an embodiment of the present disclosure. 
           [0014]      FIG. 1F  is a top-down view of the first exemplary solar concentrator photovoltaic assembly in an azimuthally rotated position according to an embodiment of the present disclosure. 
           [0015]      FIGS. 2A-2D  are views of a solar concentrator photovoltaic device at various viewing angles. 
           [0016]      FIG. 3A  is a top-down view of a second exemplary solar concentrator photovoltaic assembly in a tilted position according to an embodiment of the present disclosure. 
           [0017]      FIG. 3B  is a side view of the second exemplary solar concentrator photovoltaic assembly in the tilted position according to an embodiment of the present disclosure. 
           [0018]      FIG. 3C  is a vertical cross-sectional view of the second exemplary solar concentrator photovoltaic assembly in the tilted position along the plane C-C′ in  FIG. 3A  according to an embodiment of the present disclosure. 
           [0019]      FIG. 4  is a schematic illustration of a third exemplary solar concentrator photovoltaic assembly in an operational position. 
           [0020]      FIG. 5  is a schematic illustration of a fourth exemplary solar concentrator photovoltaic assembly in an operational position. 
           [0021]      FIG. 6A  is a top-down view of an exemplary flat panel photovoltaic assembly in a retracted position according to an embodiment of the present disclosure. 
           [0022]      FIG. 6B  is a side view of the exemplary flat panel photovoltaic assembly in the retracted position according to an embodiment of the present disclosure. 
           [0023]      FIG. 6C  is a vertical cross-sectional view of the exemplary flat panel photovoltaic assembly in the retracted position along the plane C-C′ in  FIG. 6A  according to an embodiment of the present disclosure. 
           [0024]      FIG. 6D  is a front view of the exemplary flat panel photovoltaic assembly in the retracted position according to an embodiment of the present disclosure. 
           [0025]      FIG. 6E  is a side view of the exemplary flat panel photovoltaic assembly in a tilted position according to an embodiment of the present disclosure. 
           [0026]      FIG. 6F  is a top-down view of the exemplary flat panel photovoltaic assembly in an azimuthally rotated position according to an embodiment of the present disclosure. 
           [0027]      FIG. 7  is a top-down view of two first exemplary solar concentrator photovoltaic assemblies that are loaded into a standard shipping container. The hatched area represents the area of the standard shipping container. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    As stated above, the present disclosure relates to a transportable photovoltaic system configured for rapid deployment and methods of operating the same, which are now described in further detail with accompanying figures. Throughout the drawings, the same reference numerals or letters are used to designate like or equivalent elements. The drawings are not necessarily drawn to scale. 
         [0029]    As used herein, a “photovoltaic” element is an element that is configured to generate electricity from electromagnetic radiation in the visible range, infrared range, or ultraviolet range. 
         [0030]    As used herein, a “solar concentrator” is a device that is configured to focus a substantially parallel beam, such as solar radiation, to a focus on a photovoltaic element using a lens or a mirror. 
         [0031]    As used herein, a “solar concentrator photovoltaic” element is a photovoltaic element that includes at least one solar concentrator. 
         [0032]    As used herein, a “flat panel photovoltaic” element is a photovoltaic element that does not employ any solar concentrator. 
         [0033]    As used herein, a “transportable” element is an element that is not permanently affixed to ground or any other fixture, and can be transported in commercial shipping vehicles such as a truck, a cargo ship, or a cargo plane after a pick up employing commercial construction equipment such as a crane or a forklift or by manual means. 
         [0034]    Referring to  FIGS. 1A-1F , a first exemplary solar concentrator photovoltaic assembly according to an embodiment of the present disclosure is illustrated. The first exemplary solar concentrator photovoltaic assembly is a transportable photovoltaic system.  FIGS. 1A-1D  illustrate the first exemplary solar concentrator photovoltaic assembly in a retracted position in which the first exemplary solar concentrator photovoltaic assembly is most compact.  FIG. 1B  is a side view,  FIG. 1C  is a vertical cross-sectional view along the plane C-C′ in  FIG. 1A , and  FIG. 1D  is a front view of the first exemplary solar concentrator photovoltaic assembly in the retracted position.  FIG. 1E  illustrates the first exemplary solar concentrator photovoltaic assembly in a tilted position in which the top surface of a frame  30  is at a non-zero angle from a vertical line.  FIG. 1F  illustrates the first exemplary solar concentrator photovoltaic assembly in an azimuthally rotated position in which the frame  30  is rotated around an axis that is not parallel to a horizontal plane. This axis of rotation is vertical in  FIG. 1F . In general, the frame  30  of the first exemplary solar concentrator photovoltaic assembly can be tilted and rotated by two independent angles. 
         [0035]    The first exemplary solar concentrator photovoltaic assembly comprises a plurality of solar concentrator photovoltaic devices  40  that are mounted on a frame  30 . The frame  30  is configured to hold the plurality of solar concentrator photovoltaic devices  40  through mounting structures  32 , which can be separate structures that are attached to the frame  30  or can be structures that are integrally formed with the frame, viz. as components of the frame  30 . For example, the mounting structures  32  can be a set of bolts and corresponding threaded holes. The plurality of solar concentrator photovoltaic devices  40  are thus mechanically affixed to the frame  30 . The solar concentrators shown in these illustrations employ round lenses. We note that In alternate embodiments the lens or minors may be individual units or square, rectangular and hexagonal shape. We further note that in alternate embodiments individual lens or minor elements may be combined into a single unit or parquet arrangement. 
         [0036]    Referring to  FIGS. 2A-2D , an example of a solar concentrator photovoltaic device  40  is shown at various viewing angles. Each solar concentrator photovoltaic device  40  can include a solar concentrator  42 , a heat sink  44 , and a photovoltaic cell  46 . The solar concentrator  42  is configured to focus a substantially parallel radiation in the visible range, in the infrared range, and/or in the ultraviolet range onto the photovoltaic cell  46  within the same solar concentrator photovoltaic device  40 . The plurality of solar concentrators  42  are mounted on the frame  30  and over the plurality of photovoltaic cells  46  so that solar radiation incident on the top surfaces of the plurality of solar concentrators  42  is focused onto the plurality of photovoltaic cells  46 . In one embodiment, the solar concentrator  42  can include a lens  41  and/or a mirror (not shown) that is/are configured to focus light onto the photovoltaic cell located within the same solar concentrator photovoltaic device  40 . The lens  41  of a solar concentrator  42 , (a) side panel(s)  43  of the solar concentration  42 , and a back side panel of the solar concentrator  42  can provide an enclosure. In one embodiment, the back side panel of the solar concentrator  42  can be covered by, or replaced with, the heat sink  44 . The location of a photovoltaic cell  46  is schematically illustrated in  FIG. 2A . In one embodiment, the plurality of solar concentrators  42  can be configured to provide most efficient focusing when the solar radiation impinges onto the top surfaces of the solar concentrators  42  at normal incidence, i.e., in a direction perpendicular to the top surfaces of the solar concentrators  42 . 
         [0037]    In one embodiment, at least one of the plurality of solar concentrators  42  includes a Fresnel lens, a conductive enclosure, and the heat sink  44 . At least one of the plurality of photovoltaic cells  46  is located at a focal point of said Fresnel lens. For example, a solar concentrator  42  can include sidewalls of a spun aluminum cone, and can include a Fresnel lens (not show) affixed with adhesive to the spun aluminum cone. The length of the spun aluminum cone can be equal to the sum of the focal length of a lens or a lens system included therein and the thickness of a photovoltaic cell  46  therein. In alternate embodiments the solar concentrator may comprise an array of lenses affixed to a single enclosure with the photovoltaic elements affixed to the back of said enclosure. In this case the enclosure may comprise a conductive structural material such as aluminum to dissipate heat and may further comprise multiple heat sink elements affixed to the enclosure to further dissipate heat. 
         [0038]    The photovoltaic cells  46  can be any type of photovoltaic cells known in the art. In one embodiment, the photovoltaic cells  46  can be multijunction cells having different photovoltaic junctions optimized for absorbing photons in different wavelength ranges. The multiple photovoltaic junctions are located at different depths from the topmost surfaces of the photovoltaic cells  46 . In one embodiment, each area of the photovoltaic cell  46  can be illuminated by roughly equal amounts of the solar rays in the multiple spectral regions. 
         [0039]    The heat sink  44  is configured to dissipate the heat generated from the energy focused onto the photovoltaic cell  46  and not converted into electricity. The heat sink  44  may optionally include fins and/or a fan to facilitate heat dissipation. The heat sink  44  can be mechanically and thermally coupled to the spun aluminum cone. The heat sink  44  can also be affixed to the photovoltaic  46  employing any methods known in the art including a conductive paste, screws, bolts and nuts, etc. 
         [0040]    The frame  30  is a structure configured to hold the plurality of solar concentrator devices  40 . The frame  30  can include a composite light weight material such as fiberglass including glass fibers and epoxy, composite carbon fiber including carbon fibers embedded in an epoxy matrix, or any other light weight material that can provide sufficient mechanical strength to hold the plurality of solar concentrator photovoltaic devices  40 . The frame  30  provides structural support to the plurality of solar concentrator photovoltaic devices  40 . The shape and size of the frame  30  are selected to mount the plurality of solar concentrator devices  40 . In the first exemplary solar concentrator photovoltaic assembly, seven solar concentrator photovoltaic devices  40  are arranged on a hexagonal frame, which functions as a support plate. In alternate embodiment the frame may comprise a metal such as aluminum, steel, magnesium and titanium. Combinations of metal and composite materials may be employed to further improve strength to weight performance. 
         [0041]    The frame  30  is attached to a base unit  10  through at least one variable-angle mount structure  20 . The at least one variable-angle mount structure  20  is configured to rotate the frame  30  around at least one axis relative to the base unit  10 . Each of the at least one variable-angle mount structure  20  can include a powered actuator, which can be an electrically powered strut, a hydraulically powered strut, a pneumatically powered strut, and/or a combination thereof. Each of the variable-angle mount structure  20  can include a hinge, or any other mechanically equivalent mechanical structure that enable rotation of a first element attached to a first component of the variable-angle mount structure  20  relative to a second element attached to a second component of the variable-angle mount structure  20 . The combination of a hinge (or an equivalent structure) and a powered actuator enables change of the at least one angle between the base unit  10  and the frame  30 . 
         [0042]    The at least one variable-angle mount structure  20  can include a tilt angle adjustment mount structure  22  configured to raise or lower the center of gravity of the combination of the frame  30  and the plurality of solar concentrator photovoltaic devices  40 . Additionally or alternately, the at least one variable-angle mount structure  20  can include an azimuthal angle adjustment mount structure  24  configured to rotate the combination of the frame  30  and the plurality of solar concentrator photovoltaic devices  40  within a plane in which the center of gravity of the combination ( 30 ,  40 ) remains at a same distance from a horizontal plane that is coplanar with a bottom surface of the base unit  10 . 
         [0043]    The base unit  10  is configured to be placed on a horizontal surface, such as leveled ground, without being affixed to the horizontal surface. The first exemplary solar concentrator photovoltaic assembly is not attached to any structure contiguously extending below the horizontal surface. The base unit  10  includes a heavy material that can be assembled on site, i.e., at a location of a first operation of the first exemplary solar concentrator photovoltaic assembly. In one embodiment, the base unit  10  includes a heavy material that can provide sufficient weight to the first exemplary solar concentrator photovoltaic assembly. The base unit  10  can be made of, for example, cast concrete. 
         [0044]    In one embodiment, the frame  30  can include a material having a first average density, and the base unit  10  can include another material having a second average density such that the second average density is greater than the first average density. The material of the frame  30  can be, but need not be, a composite material including fibers and a matrix material in which the fibers are embedded. For example, the frame  30  can include fiberglass (having a density of about 1.5 grams/cm 3 ) or composite carbon fiber (having a density of about 1.3 grams/cm 3 ), and the base unit can be made of cast concrete (having a density of about 2.4 grams/cm 3 ). Alternatively or additionally, the frame  30  can include one or more of steel, aluminum, magnesium, and titanium. 
         [0045]    In the first exemplary solar concentrator photovoltaic assembly, the base unit  10  can have a shape of a hollow square box without a top surface so that the plurality of solar concentrator photovoltaic devices  40  can be protected from hazardous environmental conditions (such as a hurricane or a heavy snowfall) in a retracted position, as well as minimizing a total volume of a package including the first exemplary solar concentrator photovoltaic assembly during a shipment from an original site (at which the base unit  10  is first attached to the combination of the frame  30  and the plurality of solar concentrator photovoltaic devices  40  through that at least one variable-angle mount structure  20 ) to another location. 
         [0046]    The first exemplary solar concentrator photovoltaic assembly can be employed to operate the plurality of photovoltaic cells  46  therein in an efficient manner with minimal prior notice or preparation. First, a plurality of solar concentrator photovoltaic devices  40  is attached to a frame  30 . For example, the plurality of solar concentrator photovoltaic devices  40  can be mounted to the frame  30  to form a first assembly of the frame  30  and the plurality of solar concentrator photovoltaic devices  40  at a first location, which can be a centralized manufacturing facility. The base unit  10  can be manufactured at a second location, which can be the site of installation for the first exemplary solar concentrator photovoltaic assembly. Thus, the second location can be different from the first location. 
         [0047]    The first assembly of the frame  30  and the plurality of solar concentrator photovoltaic devices  40  mounted thereupon can be transported on a wheeled vehicle such as a truck, a waterway-navigating vehicle such as a ship or a boat, or a flying vehicle such as a commercial freight plane from the first location to the second location. Subsequently, the first assembly ( 30 ,  40 ) can be attached to a base unit  10  at the second location to form a second assembly, which includes the first assembly ( 30 ,  40 ) and the base unit  10 . The at least one variable-angle mount structure  20  may be mounted on the first assembly ( 30 ,  40 ) prior to shipping from the first location to a second location, or may be attached to the first assembly ( 30 ,  40 ) and the base unit  10  at the second site. The at least one variable-angle mount structure  20  may be shipped to the second site with the first assembly ( 30 ,  40 ), or may be shipped to the second site in a different shipment. In one embodiment, the at least one variable-angle mount structure  20  may be assembled at a third site different from the first site and the second site, and be shipped to the second site for attachment to the first assembly ( 30 ,  40 ) and to the base unit  10  at the second site. 
         [0048]    Thus, an assembly, i.e., the second assembly, is formed by attaching the frame  30  to the base unit  10  through the at least one variable-angle mount structure  20 . As discussed above, the at least one variable-angle mount structure  20  is configured to rotate the frame  30  around at least one axis. 
         [0049]    The base unit  10  can be placed on a horizontal surface at a location at which the first exemplary solar concentrator photovoltaic assembly becomes operational for the first time, i.e., at a location at which the first exemplary solar concentrator photovoltaic assembly generates electricity from solar radiation. The placement of the base unit  20  at the location at which the first exemplary solar concentrator photovoltaic assembly becomes operational can be performed prior to, or after, the attachment of the first assembly ( 30 ,  40 ) to the base unit  10  through the at least one variable-angle mount structure  20 . 
         [0050]    The base unit  10  is not affixed to the horizontal surface at the location at which the first exemplary solar concentrator photovoltaic assembly becomes operational. The feature of not affixing the base unit  10 , or any component of the first exemplary solar concentrator photovoltaic assembly, to ground, any surface, or any other fixture enables the first exemplary solar concentrator photovoltaic assembly to be transportable. The first exemplary solar concentrator photovoltaic assembly remains in any place by weight and gravity, and can be moved by typical construction equipment or by a group of 2-3 workers. 
         [0051]    Once the first exemplary solar concentrator photovoltaic assembly is fully assembled and the base unit  10  is placed at the location of the first operational site, electricity can be generated from the plurality of solar concentrator photovoltaic devices  40  while the base unit  10  is placed at the location. 
         [0052]    During the operation of the first exemplary solar concentrator photovoltaic assembly in which electricity is generated from the plurality of solar concentrator photovoltaic devices  40  generates electricity from solar radiation, the frame  30  and the plurality of solar concentrator photovoltaic devices  40  mounted thereupon can be rotated, employing the at least one variable-angle mount structure  20 , to change the tilt angle of the frame  30  and the plurality of solar concentrator photovoltaic devices  40  mounted thereupon, i.e., in a direction that changes an angle between a horizontal plane and a plane of top surfaces of the plurality of solar concentrator photovoltaic devices  40 . For example, the tilt angle adjustment mount structure  22  can be employed to raise or lower the center of gravity of the combination of the frame  30  and the plurality of solar concentrator photovoltaic devices  40 . 
         [0053]    Further, during the operation of the first exemplary solar concentrator photovoltaic assembly in which electricity is generated from the plurality of solar concentrator photovoltaic devices  40  generates electricity from solar radiation, the frame  30  and the plurality of solar concentrator photovoltaic devices  40  mounted thereupon can be rotated, employing the at least one variable-angle mount structure  20 , to change the azimuthal angle of the frame  30  and the plurality of solar concentrator photovoltaic devices  40  mounted thereupon, i.e., around a direction that is perpendicular to a plane of the top surfaces of the plurality of solar concentrator photovoltaic devices  40 . For example, the azimuthal angle adjustment mount structure  24  can be employed to rotate the combination of the frame  30  and the plurality of solar concentrator photovoltaic devices  40  within a plane in which the center of gravity of the combined structure of the frame  30  and the plurality of solar concentrator photovoltaic devices  40  remains at a same distance from the horizontal plane that is coplanar with the bottom surface of the base unit  10 , which can be substantially level if in physical contact with a level ground. 
         [0054]    Because the first exemplary solar concentrator photovoltaic assembly is not affixed to ground, any horizontal surface, or any other fixture that does not move relative to ground, a construction equipment operator or a group of workers can slide the first exemplary solar concentrator photovoltaic assembly over the horizontal surface at which the base unit  10  is initially placed. The first exemplar solar concentrator photovoltaic assembly stays at a location through friction. The first exemplar solar concentrator photovoltaic assembly is thus slidable over the horizontal surface if a total sum of lateral forces can overcome the friction. Thus, first exemplar solar concentrator photovoltaic assembly is slidable with typical construction equipment such as a bulldozer or with sufficient manpower. 
         [0055]    In one embodiment, the base unit  10  can include features that enhance transportability of the first exemplary solar concentrator photovoltaic assembly. For example, the bottom portion of the base unit  10  can include a skid  10 A that is of contiguous and integral construction with other portions of the base unit  10 . In other words, the skid  10 A is an optional component of the base unit  10 . The first exemplar solar concentrator photovoltaic assembly can be moved from the original location (at which the first exemplar solar concentrator photovoltaic assembly is fully assembled) to another location over the horizontal surface employing the skid  10 A. For example, a forklift operator can insert blades of a forklift into the skid  10 A and pick up the first exemplary solar concentrator photovoltaic assembly, and then move the first exemplary solar concentrator photovoltaic assembly to the other location and place the first exemplary solar concentrator photovoltaic assembly there. In an alternate embodiment loops are cast into the concrete base to allow the use of a hook attachment and thereby enable ease of movement using a crane. 
         [0056]    In an alternate embodiment, the base unit  10  may not include a built-in skid, and a skid may be attached to the bottom surface of the base unit  10  at the time of placement of the base unit  10  at the location of the first operation of the first exemplary solar concentrator photovoltaic assembly. 
         [0057]    In one embodiment, the features that enhance transportability of the first exemplary solar concentrator photovoltaic assembly can include at least one channel  12 , which is incorporated into the base unit  12  at the time of construction of the base unit  12 , e.g., at the time of constructing a mold for the base unit  12 . The at least one channel  12  is raised over the bottommost planar surface of the base unit  10 . The at least one channel  12  can extend from one sidewall of the base unit  10  to another sidewall of the base unit  10 . 
         [0058]    The first exemplary solar concentrator photovoltaic assembly can be moved from one location to another location employing at least one substantially horizontal blade that slides into the at least one channel  12 . For example, a forklift having employing at least one substantially horizontal blade can be employed to move the first exemplary solar concentrator photovoltaic assembly. 
         [0059]    In one embodiment, the features that enhance transportability of the first exemplary solar concentrator photovoltaic assembly can include a plurality of through-hole-including structures  70 , which can be attached to the base unit  10  at the time of the assembling the first exemplary solar concentrator photovoltaic assembly. The plurality of through-hole-including structures  70  can include, for example, eye bolts that are bolted into corners of the top surface of the base unit  10 . Subsequently, the base unit  10  can be moved from the location of initial assembly to another location by lifting the assembly employing a chain or a rope that passes through the plurality of through-hole-including structures  70 . 
         [0060]    Referring to  FIGS. 3A-3C , a second exemplary solar concentrator photovoltaic assembly according to an embodiment of the present disclosure is illustrated in a tilted position. The second exemplary solar concentrator photovoltaic assembly is a transportable photovoltaic system.  FIG. 3A  is a top-down view,  FIG. 3B  is a side view, and  FIG. 3C  is a vertical cross-sectional view along the plane C-C′ in  FIG. 3A . 
         [0061]    The second exemplary solar concentrator photovoltaic assembly can include tilt angle adjustment mount structures  22  configured to tilt the combination of the frame  30  and the plurality of solar concentrator photovoltaic devices  40  relative to a horizontal surface. Additionally or alternately, the second exemplary solar concentrator photovoltaic assembly can include an azimuthal angle adjustment mount structure  24  configured to rotate the combination of the frame  30  and the plurality of solar concentrator photovoltaic devices  40  within a horizontal plane. The azimuthal angle adjustment mount structure  24  can be attached to the top surface of the base unit  10 . The tilt angle adjustment mount structure  22  and/or the azimuthal angle adjustment mount structure  24  collectively constitute at least one variable-angle mount structure that is configured to rotate the frame  30  around at least one axis relative to the base unit  10 . Each of the at least one variable-angle mount structure  20  can include a powered actuator, which can be an electrically powered strut, a hydraulically powered strut, a pneumatically powered strut, and/or a combination thereof. Each of the variable-angle mount structure  20  can include a hinge, or any other mechanically equivalent mechanical structure that enable rotation of a first element attached to a first component of the variable-angle mount structure  20  relative to a second element attached to a second component of the variable-angle mount structure  20 . The combination of a hinge (or an equivalent structure) and a powered actuator enables change of the at least one angle between the base unit  10  and the frame  30 . 
         [0062]    The shape and the size of the base unit  10  can be adjusted to accommodate the plurality of solar concentrator photovoltaic devices  40 . A base unit  10  having hexagonal sidewalls are illustrated in the second exemplary solar concentrator photovoltaic assembly. 
         [0063]    Further, the sidewalls of the base unit  10  are optional, and can be removed in some embodiments.  FIG. 4  shows a schematic illustration of a third exemplary solar concentrator photovoltaic assembly in an operational position, which is a tilted and rotated position that faces the sun. Likewise,  FIG. 5  shows a schematic illustration of a fourth exemplary solar concentrator photovoltaic assembly in an operational position, which is a tilted and rotated position that faces the sun. The third exemplary solar concentrator photovoltaic assembly and the fourth exemplary solar concentrator photovoltaic assembly are transportable photovoltaic systems. 
         [0064]    The sidewalls of the base unit  10  in the first and second exemplary solar concentrator photovoltaic assemblies are replaced with a thin vertical strip  10 B, which is a portion of the base unit  10  of the third exemplary solar concentrator photovoltaic assembly or a portion of the base unit  10  of the fourth exemplary solar concentrator photovoltaic assembly. 
         [0065]    Referring to  FIGS. 6A-6F , an exemplary flat panel photovoltaic assembly according to an embodiment of the present disclosure is illustrated. The exemplary flat panel photovoltaic assembly is a transportable photovoltaic system.  FIGS. 6A-6D  illustrate the exemplary flat panel photovoltaic assembly in a retracted position in which the exemplary flat panel photovoltaic assembly is most compact.  FIG. 6B  is a side view,  FIG. 6C  is a vertical cross-sectional view along the plane C-C′ in  FIG. 6A , and  FIG. 6D  is a front view of the exemplary flat panel photovoltaic assembly in the retracted position.  FIG. 6E  illustrates the exemplary flat panel photovoltaic assembly in a tilted position in which the top surface of a frame  30  is at a non-zero angle from a vertical line.  FIG. 6F  illustrates the exemplary flat panel photovoltaic assembly in an azimuthally rotated position in which the frame  30  is rotated around an axis that is not parallel to a horizontal plane. This axis of rotation is vertical in  FIG. 6F . In general, the frame  30  of the first exemplary solar concentrator photovoltaic assembly can be tilted and rotated by two independent angles. 
         [0066]    The exemplary flat panel photovoltaic assembly can be derived from the first, second, third, or fourth exemplary solar concentrator photovoltaic assembly by substituting a flat panel photovoltaic device  140  for each of the solar concentrator photovoltaic device  40 . Except for the difference between a plurality of flat panel photovoltaic devices  140  and a plurality of solar concentrator photovoltaic devices  40 , the exemplary flat panel photovoltaic assembly can be assembled, transported, and operated in the same manner as the first, second, third, and fourth exemplary solar concentrator photovoltaic assemblies. 
         [0067]    Because the base unit  10  is not affixed to ground, any surface, or any other fixture, the various photovoltaic assemblies of the present disclosure are transportable. Thus, the various photovoltaic assemblies of the present disclosure can be picked up from the site of the original assembly and initial operation, for example, by a crane, a forklift, or a working crew of a few people, and located into a standard shipping container to be shipped on land, on waterways, or in air in any vehicle configured to transport shipping containers. 
         [0068]      FIG. 7  is a top-down view of two first exemplary solar concentrator photovoltaic assemblies that are loaded into a standard shipping container. The hatched area represents the area of the standard shipping container. In general, multiple photovoltaic assemblies, which can include any of the first, second, third, and fourth solar concentrator photovoltaic assemblies and/or one or more of the flat panel photovoltaic assemblies, can be loaded into a standard shipping container after initial assembly at a first operational site, i.e., the location at which the first assembly of the frame  40  and photovoltaic devices ( 40  or  140 ) are assembled. 
         [0069]    In one embodiment, the size and shape of the base unit  10  and optionally, the size and shape of the solar concentrator photovoltaic devices  40  can be adjusted to fit in a standard shipping container employed for trucks. A standard shipping container has a width of 8 feet, a height of 9 feet and six inches, and a length of 48 feet or 53 feet. 
         [0070]    In order to facilitate pick up of the various photovoltaic assemblies of the present disclosure by construction equipment or by a working crew, the base unit  10  of the various photovoltaic assemblies of the present disclosure can be provided with any hard points and/or slots known in the art for lifting with a forklift or a crane. 
         [0071]    In one embodiment, the various photovoltaic assemblies can be provided with peripheral components (not shown) for immediate operation upon placement. Such a “drop and plug” operational mode can be enabled for the various photovoltaic assemblies by providing an automated control system (such as a computer), a power inverter that transforms an alternating current (AC) into a direct current (DC), and/or a battery storing sufficient electrical charge to enable positioning of the frame  30  and the plurality of photovoltaic devices ( 40  or  140 ). The battery can be employed to store sufficient to allow initial power up and orientation and stowage in emergency loss of load situations for the various photovoltaic assemblies of the present disclosure. 
         [0072]    While the present disclosure has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in forms and details can be made without departing from the spirit and scope of the present disclosure. It is therefore intended that the present disclosure not be limited to the exact forms and details described and illustrated, but fall within the scope of the appended claims.