Abstract:
A solar energy collection system for converting solar energy to electricity that includes solar arrays mounted on a frame. Each array is set on a tracker head that is supported on a pedestal; each pedestal mounts onto a beam. Elevators pivot the arrays, where each elevator is made up of a shaft with a threaded end coupled to a drive nut. An upper end of each drive nut gimbal mounts to a portion of the tracker head; rotating a lower end of each shaft raises or lowers the drive nut, thereby pivoting each array. The vertical shafts are ganged together and driven by a single motor. Further included with each pedestal are azimuth orientation shafts that also mount to each tracker head. Rotating each orientation shaft adjusts an azimuth of an associated array. The orientation shafts are ganged together and are rotated by a single motor.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 61/621,840; filed Apr. 9, 2012, the full disclosure of which is hereby incorporated by reference herein for all purposes. 
    
    
     BACKGROUND 
     1. Field of Invention 
     The invention relates generally to a drive system for aligning photovoltaic cells. More specifically, the invention concerns aligning photovoltaic cells mounted on multiple pedestals with a single drive system. 
     2. Description of Prior Art 
     Converting solar energy into electricity is often accomplished by directing the solar energy onto one or more photovoltaic cells. The photovoltaic cells are typically made from semiconductors that can absorb energy from photons from the solar energy, and in turn generate electron flow within the cell. A solar panel is a group of these cells that are electrically connected and packaged so an array of panels can be produced; which is typically referred to as a flat panel system. Solar arrays are typically disposed so they receive rays of light directly from the source. 
     Some solar collection systems concentrate solar energy by employing curved solar collectors that concentrate light onto a solar cell. The collectors are often parabolic having a concave side and a convex side, where the concave side typically faces towards the sun and reflects sunlight onto a strategically positioned receiver. Receivers for use with concentrated solar energy are generally equipped with a photovoltaic cell that has a higher performance than those in flat panel systems. The concave configuration of the reflective surface converges reflected rays of solar energy to concentrate the rays when contacting the receiver. Concentrating the solar energy with the curved collectors can project up to about 1500 times the intensity of sunlight onto a receiver over that of a flat panel system. As the cells currently do not convert all the solar energy received into electricity, substantial heating occurs on the receiver that can damage the cells unless the thermal energy accumulated on the receiver can be transferred elsewhere. 
     Solar collection systems that concentrate solar energy generally employ a number of collectors; each having a reflective side configured to focus the reflected light onto a solar receiver. Because the solar energy is concentrated, the reflective surface area exceeds the conversion cell area by a significant amount. Solar collection and conversion systems often consolidate the collectors into a solar array, thereby boosting the electricity generating capacity of the conversion system. The collectors within an array are typically positioned within a localized area to minimize the total area of the array. 
     SUMMARY OF THE INVENTION 
     Disclosed herein are systems and methods for collecting solar energy which is converted into electricity. In one example provided herein is a solar energy collection system which includes a frame having an elongate beam, elongate pedestals each having an end coupled with the beam, a solar array pivotingly mounted on an end of each pedestal distal from the beam, an inclination assembly in each pedestal having a portion in contact with the array on the pedestal. The inclination assembly is selectively elevated to a range of distances above the pedestal, so that when the portion is elevated an inclination of the array changes. Also included in each pedestal is an azimuth assembly that couples with the array on the pedestal, and that is rotatable about an axis of the pedestal. An inclination linkage, with a portion disposed in the beam, couples the inclination assembly to an inclination motor. Similarly, an azimuth linkage, with a portion disposed in the beam, couples the azimuth assembly to an azimuth motor. In an example, the inclination assemblies each include a shaft, a nut threadingly engaged with an upper end of the shaft proximate the solar array, a lower end of the shaft projecting into the beam, and a pulley on a lower end of the shaft. In this example, the inclination linkage includes a belt that engages a pulley on the inclination motor and also engages the pulley on the lower end of each shaft. The azimuth assembly can have a tubular member in each pedestal that circumscribes a portion of an inclination assembly, an upper end coupled with a solar array, a lower end in the beam, a pulley on the lower end. In this example, the azimuth linkage includes a belt that engages a pulley on the azimuth motor and also engages the pulley on the lower end of each tubular member. The system can further optionally include a multiplicity of beams with pedestals, solar arrays on the pedestals, in each pedestal an inclination assembly and an azimuth assembly, an inclination linkage and an azimuth linkage in each beam, an inclination motor coupled to each inclination linkage, and an azimuth motor coupled to each azimuth linkage. This example, can further have cross members coupling together the beams to define a self-supporting structure for supporting the solar arrays. An electrical circuit can optionally be included that is connected to the solar array and that includes a load powered by electricity generated by the solar array. In an example, the solar array has solar collectors, and a receiver strategically disposed away from each solar collector, so that when solar energy reflects from a collector, an image is formed on a receiver that is converted into electricity in the receiver. 
     Also disclosed herein is a solar energy collection system which includes an array of solar collectors pivotingly mounted on a support frame. An inclination assembly is provided in the support frame and has a portion selectively disposed along a range of elevations that is coupled with the array, so that when an elevation of the portion changes, an inclination of the array is changed. Further included is an azimuth assembly coupled with the array, the azimuth assembly is coaxially disposed within the support frame and rotatable about an axis of the azimuth assembly, so that when the azimuth assembly rotates, an azimuth of the array is changed. The system also includes an inclination motor coupled with the inclination assembly and an azimuth motor coupled with the azimuth assembly. In this example, the support frame can also have a pedestal having a lower end that mounts in an elongate beam and an upper end coupled with the solar array. Optionally, multiple pedestals can be mounted on the frame, where each pedestal has a solar array, an inclination assembly, and an azimuth assembly, and which defines a solar unit. In an example, multiple solar units can be arranged in rows and coupled together by cross members. In an example, each solar unit has a single inclination motor and a single azimuth motor. 
     A method of converting solar energy to electricity is provided herein, and that in one example includes providing a solar energy collection system with solar arrays mounted on a frame, an azimuth positioning system, and an inclination positioning system and transporting the solar energy collection system to a designated location having a mounting surface. The frame is set on a mounting surface, and the azimuth positioning system and the inclination positioning system are activated. The solar arrays are oriented in a designated orientation with the azimuth positioning system and the inclination positioning system and solar energy is reflected from solar collectors to receivers in the solar arrays that generate electricity in response to exposure to solar energy. The designated orientation can be an orientation wherein the solar collectors receive a maximum amount of solar energy. The method can further include reorienting the solar arrays in response to a change in a relative position of the sun. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic view of an example embodiment of a solar energy system in accordance with the present invention. 
         FIG. 2  is a side perspective view of an example of an array of  FIG. 1  coupled with a drive system in accordance with the present invention. 
         FIG. 3  is a side sectional view of a portion of the array and drive system of  FIG. 2  in accordance with the present invention. 
         FIG. 4  is a partial sectional and perspective view of an example of a portion of the drive system of  FIG. 2  in accordance with the present invention. 
         FIG. 5  is a perspective view of an alternate embodiment of the solar energy system of  FIG. 1  and in accordance with the present invention. 
     
    
    
     While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF INVENTION 
     The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. 
     It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the improvements herein described are therefore to be limited only by the scope of the appended claims. 
       FIG. 1  provides in schematic view an example embodiment of a solar energy collection system  10  having a curved collector  12  and a reflective surface  14  on a concave side of the collector  12 . In one example embodiment the collector  12  has a parabolic shape. In the example of  FIG. 1 , the collector  12  is disposed in the path of solar rays  16  that strike the reflective surface  14  and are redirected as reflected rays  17 . The reflected rays  17  are shown traveling on a path towards a solar receiver  18  shown spaced back from the reflective surface  14 . The collector  12  is shaped and contoured so that the reflective rays  17  form a defined image  19 . In the example of  FIG. 1 , a photovoltaic cell  20  is shown on the receiver  18  that coincides with formation of the image  19 . The image  19  has an area or footprint that is smaller than that of the reflective surface  14 , but its flux density more concentrated than that of the solar rays  16 . The photovoltaic cell  20  converts the concentrated energy in the image  19  into electrical current that flows into a circuit  22  shown connected to the photovoltaic cell  20 . Further illustrated in the example of  FIG. 1 , is an electrical load  24  schematically represented within the circuit  22 . Electrical lines  26 ,  27  provide electrical communication between the photovoltaic cell  20  and load  24 , thereby completing the circuit  22 . 
     An example embodiment of arrays  30  of a solar energy collection system  10  ( FIG. 1 ) are provided in a perspective view in  FIG. 2 . In this example, each of the arrays  30  are mounted on a tracker system  31  for selectively adjusting the azimuth and inclination of each array  30 . The embodiment of the tracker system  31  of  FIG. 1  includes pedestal assemblies  32  on which each of the arrays  30  are mounted. Each example pedestal assembly  32  is shown as a generally elongate vertical member whose lower end mounts on an elongate and longitudinally oriented beam  34 . In the example of  FIG. 2 , the beam  34  is a generally hollow member with a rectangle like cross section. As will be described in more detail below, an inclination linkage couples an inclination assembly in each pedestal assembly  32  with an inclination motor  36 . Inclination motor  36  is schematically illustrated disposed adjacent an end of the beam  34 , and provides a motive means for adjusting the inclination of the arrays  30 . Similarly, azimuth linkages couple azimuth assemblies in each pedestal assembly  32  with a schematically illustrated motor  38  for adjusting the azimuth of each of the arrays  30 . Shafts  40 ,  42  provide rotational output respectfully from motors  36 ,  38  to pulleys  44 ,  46 . The pulleys  44 ,  46 , engage belts  48 ,  49  that extend within the beam  34  for transmitting rotational force from the motors  36 ,  38  to the linkages. In the example of  FIG. 2 , the row of arrays  30  mounted on pedestals  32  projecting from the beam  34  define a solar unit  50 . 
     Referring now to  FIG. 3 , an example of a pedestal  32  is provided in a side sectional view and which shows an inclination assembly  52  therein. In the illustrated embodiment, the inclination assembly  52  includes an elongate shaft  54 . Linkage assembly  55  for coupling inclination assembly  52  with inclination motor  36  includes belt  48  which engages a pulley  56  shown coaxially coupled on an end of the shaft  54 . Thus, as illustrated by the directional arrows, longitudinally moving belt  48  rotates pulley  56 , which in turn rotates shaft  54 . In the example of  FIG. 3 , the pulley  56  has a diameter that exceeds a diameter of the shaft  54 . A nut  58  is illustrated threadingly engaged with a threaded end of the shaft  54  distal from the pulley  56 ; where the shaft  54  is rotatable with respect to the nut  58 . Adjacent the nut  58  is a tracker head  60  shown coupled with a lower surface of an array  30 . The example of the tracker head  60  of  FIG. 3  includes a pivot member  62  and an azimuth plate  64 . In this example, both the pivot member  62  and azimuth plate  64  have a planar mid-section, with planar end portions that project substantially perpendicular from opposing ends of the mid-section. Thus both member  62  and plate  64  have generally “U” shaped cross sections. The distance between the inside of the end portions of the azimuth plate  64  exceeds the distance between the outside of the end portions of the pivot member  62 . The difference in distances allows the pivot member  62  to be positioned between the end portions of the azimuth plate  64 . A tubular hinge member  66  extends between end portions of the pivot member  62 . A pin  68 , which extends between opposing end portions of the azimuth plate  64 , inserts into the hinge member  66 . Thus pivotingly mounting the pivot member  62  between vertical portions of the azimuth plate  64 . Further in the example of  FIG. 3 , the hinge member  66  is offset from the middle of the mid-section. 
     The embodiment of the pedestal  32  of  FIG. 3  further includes a tubular azimuth drive assembly  70  shown having a cylinder  72  circumscribing the shaft  54 . Upper end of cylinder  72  connects to nut  58 , and a pulley  73  attaches to a lower end of cylinder  72 ; where pulley  73  is substantially coaxial with pulley  56 . Pulley  73  and belt  49  form an azimuth linkage assembly  74  which couples azimuth drive assembly  70  to azimuth motor  38 . Distal from the pulley  73 , the cylinder  72  inserts into a bore  75  formed axially through a horizontal portion of the azimuth plate  64 . The bore  75  in the mid-section of the azimuth plate  64  provides for passage of the shaft  54  therethrough. A tubular pedestal piling  76  circumscribes the cylinder  72  and provides structural support for the elevator assembly  58  and azimuth drive member  70 . Although cut away for clarity in the example of  FIG. 3 , piling  76  also circumscribes pulley  56  and its lower end couples to beam  34  ( FIG. 2 ). 
     Still referring to  FIG. 3 , upper ends of the vertical portions of the pivot member  62  are in contact with a lower end of the array  30 ; and an upper surface of the nut  58  contacts a lower surface of the pivot member  62 . Embodiments exist wherein the nut  58  is coupled with one of the pivot member  62  or azimuth plate  64 . So instead of rotating with rotation of the shaft  54 , by virtue of its threaded engagement with shaft  54 , the nut  58  is urged in a direction axially with the shaft  54 . Thus rotating the elevator assembly  58  vertically displaces the nut  58  with respect to the azimuth plate to exert a vertical force onto the pivot member  62  and changes an inclination of the array  30 . Depending on the rotational direction of the elevator assembly  58 ; the pivot member  62  pivots upward or downward. By rotating the cylinder  72 , the attached azimuth plate  64  is also rotated. As the azimuth plate  64  rotates, so do the pivot member  62  and array  30 , due to the respective couplings between these members. Thus rotating the azimuth plate  64  in turn changes the azimuth of the array  30 . Accordingly, the inclination and/or azimuth of the array  30  can be adjusted by respectively rotating the elevator assembly  52  and azimuth drive assembly  70 . 
     Schematically illustrated in a partial sectional view in  FIG. 4  is an example of one of the pedestal assemblies  32  that mount to the beam  34  ( FIG. 2 ). In the example shown, a lower end of the pedestal piling  76  inserts into an upper surface of the beam  34  and mounts thereon. Also in the embodiment of  FIG. 4 , shaft  54  and cylinder  72  are substantially coaxial with an axis A X  of piling  76 . Further shown is that the pulley  56  couples with belt  48 . In this example, the belt  48  extends substantially the length of beam  34  ( FIG. 2 ) and is positioned to engage pulleys (not shown) of all pedestal assemblies  32  ( FIG. 2 ). Accordingly, all pulleys  56  that are part of an inclination linkage assembly  51  ( FIG. 3 ) are selectively rotatable by operation of the same motor  36 . Also, pulleys  74  of each of the pedestal assemblies  32  couple with belt  49  so that they are selectively rotatable by operation of motor  38 . Thus the inclination and azimuth of multiple arrays  30  can be selectively positioned by motors  36 ,  38 ; wherein in an example, all arrays  30  can be simultaneously positioned by motors  36 ,  38 . Further illustrated in  FIG. 4  are bearings  78  disposed between the pedestal piling  76  and the cylinder  72  so the piling  76  can provide vertical support for the cylinder  72  without introducing an interfering amount of friction. Similarly, bearings  80  are shown optionally provided between the shaft  54  and the cylinder  72 . 
     Designated or desired azimuths and inclinations of the arrays  30  can be based on an orientation that results in a maximum amount of electricity delivered to circuit  22  ( FIG. 1 ). Tracking systems can be relied on for estimating a designated orientation, and a controller for directing operation of the motors  36 ,  38  so that the designated orientation of the arrays  30  is achieved. In an example of operation, as the path of the sun rays changes relative to the arrays  30 , so does the designated orientation. When the tracking system recognizes that a difference between the orientation of the arrays  30  and a designated orientation exceeds a designated threshold, the motors  36 ,  38  can be operated so that the orientation of the arrays  30  is substantially equal to or within an operational tolerance of the designated orientation. 
     A significant weight and cost advantage is realized by orienting multiple arrays  30  with motors  36 ,  38 , rather than a motor or motors required for each array. Additionally, because the “ganged” arrays  30  are secured on the pedestals  32  and beam  34 , the need to build a support at the installation site is eliminated. Optionally, elongate stabilizer beams  82  ( FIG. 2 ) can be included with the system  10  that connect to the beam  34  and project laterally therefrom to maintain a vertical orientation of the pedestal assemblies  32 . In another example embodiment provided in  FIG. 5 , multiple solar units  50  of arrays  30 , pedestal assemblies  32  and beams  34  can be connected together by cross members  84 . In this example, the solar units  50  are arranged substantially parallel with one another, with the cross members  84  perpendicular to the beams  34 . Other arrangements of structure are available that form a modular system  10 , such as the cross members  84  being at oblique angles to the beams  34 . Optionally, embodiments of the system  10  include any number of rows of solar units  50 , wherein each unit  50  can have any number of arrays  30 . A self-supporting structure is thereby created that is mobile, and can be readily deployed without fabricating a foundation or coupling to an underlying surface. 
     In one example of operation, one or more rows of solar units  50  are provided to form a system  10 , where the system  10  is self-supporting with array  30  stable on its associated pedestal  32 . Additionally, the self-supporting system  10  is modular and can be substantially fabricated before being transported to a designated location for its use. At the designated location, the system  10  can be set on a mounting surface  86 . Example mounting surfaces  86  include the ground, another structure (e.g. building, house, decking, etc.), or a support slab. Fasteners  88  schematically shown through the beam  34  can be used to anchor the system  10  depending on the location and conditions of use. The arrays  30  can be oriented to collect a maximum amount of solar energy by actuating the motors  36 ,  38 ; which drives the inclination and azimuth assemblies  52 ,  70  ( FIG. 3 ) to position the arrays  30 . Various sun acquisition techniques can be employed to determine the designated orientation of the arrays  30 . Moreover, tracking techniques are available for reorienting the orientation of the arrays  30  to track movement of the sun. 
     The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. For example, multiple rails can be ganged together so that the arrays mounted on each rail can be tilted with actuation of a single motor and/or rotated with a single motor. Optionally, rack and pinion components, or the like, may be used in lieu of the belts  48 ,  49  and pulleys  56 ,  74 . Further, the system and method described herein for orienting an array of solar collectors can apply to flat panel photovoltaic cells, low concentration CPV, CSP (heliostats), high concentration photovoltaic cells, and combinations thereof. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.