Abstract:
A system for collecting light energy through smaller photovoltaic cells (PV cell) such that the length of the PV cell is much greater than the width. The PV cells may be linear strung together and placed within a recess of a frame or pan that is part of a PV module. The PV module includes a lens and waveguide which provide advantages for focusing and concentrating the light energy by positioning a waveguide over the smaller PV cell and engaging the PV cell with a lens such that the lens is held by the frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application incorporates the following patents or applications, in their entirety, by reference: U.S. Pat. No. 8,705,914 titled REDIRECTING OPTICS FOR CONCENTRATION AND ILLUMINATION SYSTEMS and U.S. Pat. No. 8,561,878 titled LINEAR CELL STRINGING. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates generally to methods and systems for light collection and delivery. These systems relate more specifically to the use of optics to concentrate sunlight into photovoltaic receivers and the apparatus used for this light collection. 
       RELATED ART 
       [0003]    Photovoltaic (PV) cells or solar cells are electronic devices that convert solar energy, or light energy into electricity. PV cells are, roughly, manufactured from circular silicon wafers and are often cut into a rectangular shape with the corners cut off. The PV cells are then placed within a PV module side by side. A standard PV module may include cells placed in a frame in a format of 6 cells by 10 cells (6×10), or 6 cells by 12 cells (6×12) or other formats. 
         [0004]    The PV cells in a PV module are wired or soldered together in a series to create a higher additive voltage. The PV modules are necessarily waterproof or water-resistant so as not to short the electronics and electrical connections. Often a sheet of glass covers a sun-facing side of the module. Each PV module includes its own power box that captures the electricity produced from the PV cells. 
         [0005]    PV cells tend to have a standard length and width of, roughly, 156 mm×156 mm. These are then placed together in a PV module as set forth above. PV cells may be cut into many different sizes and or shapes but the industry standard tends to be the 156 mm×156 mm. 
         [0006]    Mirrors and other reflectors have been used in the solar energy art o help harness more of the solar energy into PV cells. Often times the reflectors do riot capture 100% of the solar energy because some energy is lost in the reflection. 
         [0007]    Edge collectors or optical waveguides are used for collection and concentration of light; in particular, sunlight. An edge collector or optical waveguide is defined for this application as an optical device that receives light from a top surface, and delivers the concentrated energy to the edge of the device. In practice, optical waveguides are generally of the type described in U.S. Pat. Nos. 7,664,350 and 7,672,549. Other types of optical waveguides include luminescent solar concentrators, or dye luminescent solar concentrators. 
       SUMMARY 
       [0008]    This disclosure, at least in one aspect, relates to the use of frames for holding PV cells, optical waveguides, and a lens or lenses to aid in concentrating solar energy onto those PV cells and the method of assembly. The frame may include a recessed track or grooves or voids to hold and capture PV cells that have been cut and soldered together linearly in a manner the same or similar to that described in U.S. Pat. No. 8,561,878. The PV cells are cut into strips, instead of the standard 156 mm×156 mm. 
         [0009]    The PV cells in the present description may be cut from the wafer into six thinner PV cells which may be 15 mm×125 mm. The PV cells may lay flat within the grooves. The PV cells may be secured by some type of adhesion or not. The track may be of a standard width to fit the linear PV cells so that the PV cells cannot shift laterally after being placed within the groove. The linear PV cells may lay within a frame which may comprise six tracks that the linear PV cells fit in. The linear PV cells may then be strung together 10 PV cells in length. The outlay of the PV cells may then be 6×10 PV cells; however, although the PV cells are thinner (15 mm×125 mm) they are able to capture as much solar energy and produce as much electricity as a standard cell of 156 mm×156 mm because of the optical waveguide and lens. 
         [0010]    The optical waveguide may be positioned just above, or superior, the PV cells. The assembly of the PV module may include a gel or other optically transparent material that engages the PV cell and the waveguide to allow transfer of solar energy with little to no reflective loss of the solar energy. A lens is positioned superior, or on top of, the waveguide to concentrate the light or solar energy into the waveguide. The waveguide then uses total internal reflection to transfer the solar energy or light on the PV cell or the receiver. 
         [0011]    At either end of the frame brackets may be place to “cap” the ends of the PV module. A waterproof or water resistant material is provided around the circumference of the frame to prevent water ingress into the assembly or system. At least one end bracket may include a vent to allow moisture or condensation to escape the internal structure of the PV module, however, preventing the ingress of any such moisture. GORE-TEX® may be used to cover the vents to allow moisture to pass in a single direction as described herein. 
         [0012]    This assembly does not require its own power box top capture the electricity from the cells. The assembly allows for direct electrical lines to feed into an electrical system or multiple PV module into a signal electric gathering receptacle, power box or battery. 
         [0013]    Other aspects, as well as the features and advantages of various aspects, of the disclosed subject matter will become apparent to those of ordinary skill in the art from the ensuing description, the accompanying drawings, and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    In the drawings: 
           [0015]      FIG. 1  illustrates a perspective view of an assembly with a frame, without a waveguide or a lens; 
           [0016]      FIG. 2  illustrates a closer perspective view, and partial cutout, of the assembly of  FIG. 1 ; 
           [0017]      FIG. 3  illustrates a cutout view of a recess and a single photovoltaic cell (PV cell) of the assembly of  FIG. 1 ; 
           [0018]      FIG. 4  illustrates a side view of the lens and waveguide of the assembly; 
           [0019]      FIG. 5  illustrates a side view of the assembly of  FIG. 1  if the frame was for a single PV cell or PV cell string and is for illustrative purposes only. 
           [0020]      FIG. 6  illustrates an exploded perspective view the assembly with with the frame, waveguide and lens; 
           [0021]      FIG. 7  illustrates a side view of at least one end cap or end bracket; 
           [0022]      FIG. 8  illustrates a side view of the end bracket of  FIG. 6  engaged with the frame; 
           [0023]      FIG. 9  illustrates a perspective view of an alternate embodiment of the assembly of  FIG. 1 ; 
           [0024]      FIG. 10  illustrates a side view of the assembly of  FIG. 9 ; 
           [0025]      FIG. 11  illustrates a side view of an alternate embodiment end cap or end bracket; 
           [0026]      FIG. 12  illustrates a top view of the alternate embodiment of  FIG. 9  with the PV cells in place; and 
           [0027]      FIG. 13  illustrates a side view of the end bracket of  FIG. 11  and frame of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0028]      FIG. 1  illustrates an embodiment of a PV module assembly  10  with PV cells  8 . The assembly  10  includes a body  12 , or frame, which may have a longitudinal length  13  longer than its width  15 . The body  12  may be a rectangular shape and may have sharp or rounded corners; however, other polygonal shapes are contemplated. The body  12  may comprise a top portion  14  that may include multiple grooves  16  or recesses extending the length  13  of the body  12 . The body  12  may also include at least a first wall  18  and a second wall  20  extending along the longitudinal length  13  around the periphery of the body  12  wherein the first wall  18  and second wall  20  are opposite from each other on opposite sides of the body  12 . The first wall  18  may extend superiorly from a first side  24  of the body  12  and the second wall  20  may extend superiorly from a second side  26  of the body  12 . The first and second walls  18 ,  20  may include shoulders  22  that may extend laterally from the walls in a direction lateral to a center of the body  12 . The shoulders may allow for a lens with a waveguide to be positioned on those shoulders  22 . 
         [0029]    The body may also include a third wall  28  extending along the width  15  from a third side of the body  12  and a fourth wall  30 , opposite the third wall  28 , extending long the width  15 . The third and fourth walls  28 , 30  may also extend superiorly from the body  12  and may include shoulders  22  the same or similar to those extending laterally from the center of the body  12 . The assembly  10  may comprise a cavity  32 , or trough, between the walls  18 ,  20 ,  28 ,  30  creating a trough. 
         [0030]    The third wall  28  may comprise at least one aperture, or a first aperture  29 , to allow for a Multi-Contact (MC4) connectors, electrical connector or other transmission wire to pass therethrough. The first aperture  29  may include an insulator as well as a rubber cap or stopper, or other means known for securing a wire without allowing other materials to enter or exit. The rubber cap may maintain the wire within the aperture of the third wall  28  while also preventing ingress of water or moisture or other materials. The first aperture may be biased laterally toward one side of the third wall  28  close in proximity to the first wall  18 . A second aperture  31  may be positioned laterally on the third wall  28  close in proximity to the second wall  20 . The second aperture may comprise a rubber cap as well that performs in the same or substantially the same manner as the rubber cap of the first aperture  29 . 
         [0031]    The fourth wall  30  may include a third aperture  33  which may include a vent, or semi-permeable vent, to allow for moisture to escape from the cavity  32 . The third aperture may be circular hole or an elliptical hole or any other circular or polygonal shape. The vent may semi-permeable and may be comprised of a breathable material that allows moisture to escape but prevents the penetration of moisture, much like GORE-TEX® or other possible polymer or venting material. The vent may be positioned along any portion of the fourth wall  30 . It will be appreciated that multiple vents may be disbursed on any of the walls disclosed herein. 
         [0032]    The recesses  16  may extend almost entirely from the third wall  28  to the fourth wall  30 . The recesses  16  may be parallel to each other and the body  12  may include anywhere from four recesses to eight or more recesses. Some of the figures show an embodiment with six recesses. The recesses  16  may also run parallel to the first wall  18  and the second wall  20  in a longitudinal direction. Each recess  16  may extend the entire length of the body  12  or each recess may terminate prior the third wall  28  or the fourth wall  30 . Each recess  16  may be configured to receive a solar cell string  34  as defined in U.S. Pat. No. 8,561,878 which is incorporated herein by reference. The solar cell strings  34  may slidably fit within the recesses  16 . Each solar cell string  34  may be ten PV cells in length soldered together with electrical tabbing ribbon or by other electrical connection means. It will be appreciated that the length and width of the PV cells and PV cell strings  34  is dependent on the length of the body  12  of the assembly  10  and by the length and width of the recesses  16  of which the cell strings  34  lay. Standard PV modules incorporate a six cell by ten cell configuration and for ease in describing the present embodiment six cells by ten cells have also been utilized; however the cells described herein may be much narrower or thinner such as 15 mm×156 mm instead of 156 mm×156 mm. 
         [0033]    Referring to  FIGS. 2 and 3 , at the end of each cell string  34  electrical tabbing ribbon  35 , or other means of electrical connection, may extend beyond the cell strings  34  and a separate tabbing ribbon which may run perpendicular to the tabbing ribbon(s) from the cell strings  34 . The perpendicular running tabbing ribbons may be connected to the cell strings  34  tabbing ribbon(s), either through soldering or crimping or some other electrical contact means. This perpendicular tabbing ribbon is then connected to, wired to, soldered to or attached by other electrical means to the wires which pass through the rubber caps which pass through the apertures in the third wall  28 . These electrical connections then allow the energy gathered by the PV cells of the cell string  34  to pass from the PV module to the energy harvester or battery. 
         [0034]    Referring to  FIG. 4 , a lens  36 , or glass, is incorporated into the PV module  10  as the outer layer or top piece of the PV module  10 . The lens  36  may be flat and smooth on a top portion  38  and ridged on the bottom portion  40 . The ridges  42  are convex protrusions extending in a pattern on the bottom portion  40  wherein the pattern may consist of a large convex protrusion followed by a small convex protrusion followed by a five or six medium sized convex protrusions and then another small convex protrusion followed by a large protrusion. The medium sized protrusions are larger than the small protrusions but smaller than the large protrusions. It will be appreciated that the number of protrusions or ridges  42  and pattern may be altered and fewer medium ridges  42  may be used and a greater number of smaller or larger ridges  42  may also be used. This ridges  42 , or convex protrusions, extend longitudinally the length of the lens  36  and run parallel to the recesses  16  of the body  12 . The shape and configuration of the ridges  42  is for proper focus of light or light energy. 
         [0035]    The lens may be made of glass, polymer, acrylic or other transparent material that provides the same means and methods of focusing the light to the waveguide. 
         [0036]    A waveguide  44  is positioned against the lens  36  on the ridged bottom portion  40 . The waveguide  44  may be secured in a number of different ways including, but not limited to, glue, silicone snap or press fit into grooves which may be carved into the lens  36 . The waveguide and lens must be appropriately positioned with respect to one another with a tolerance of not great than plus or minus 0.1 mm. The waveguide  44  interacts with the lens in a manner as set forth in U.S. Pat. No. 8,705,914 which is incorporated herein by reference. The waveguide  44  is configured to sit within the cavity  32  and an edge  46  of the waveguide is positioned, or sits, just above the narrow PV cell. The waveguide  44  collects the light and concentrates the light at the edge  46  of the waveguide  44  for collection on a receiver, or the PV cell. The waveguide  44  may or may not touch the PV cell. In order for maximum light energy to be captured it is optimal that no air gap exist between the waveguide  44  and receiver, or PV cell. In the event the waveguide  44  is not in contact with the PV cell a non-refractive, index matching gel, or silicone, may be placed on top of the PV cell. The gel would engage both the PV cell and the waveguide  44  such that there is no air gap between the edge  46  of the waveguide  44  and the PV cell. The gel may be maintained within the recesses  16  such so that it does not spill onto the body  12  beyond the recesses  16 . 
         [0037]    The waveguide  44  may be made of materials such as acrylic, polymer, glass or other transparent material. However, the materials used may comprise those elements which allow refraction of light in the manner set forth in U.S. Pat. No. 8,705,914. 
         [0038]      FIG. 5  depicts a single PV module assembly  10  for explanation purposes only and represents a single lens  36 , waveguide  44 , and frame  12 . However, it will be appreciated that the PV module assembly described herein is intended to be a standard length width and size of a typical PV module. In this illustration it is readily recognizable the recess  16  at the base of the frame  12  that holds the PV cell. Likewise the walls which include the shoulder  22  that rests the lens  36  with the waveguide  44  secured to the lens  36 . 
         [0039]    Referring to  FIG. 6 , each narrow PV cell (15 mm×156 mm, or similar) may include a waveguide  44  in order to concentrate enough light energy to reach the same efficiency of a standard PV cell (156 mm×156 mm). In a standard PV module comprising ten PV cells by six PV cells each cell may include a waveguide thus requiring sixty (60) waveguides for the PV module assembly  10 . Multiple waveguides  44  may be secured to a single lens  36  wherein the lens length and width are sufficient to reside on the shoulders  22  of the walls  18 ,  20 ,  28 ,  30 . The length of the waveguide  44  may be substantially similar to the length of the PV cell thus maximizing the light energy over the length of the PV cell. Each waveguide  44  may laterally touch an adjacent waveguide  44 ; however because of the length of a PV cell a waveguide  44  may not touch or be in direct contact with another waveguide on its proximal and distal ends. It will be appreciated that a single extruded waveguide may be utilized, or single piece, or single waveguide  44 , may be machined that may sit within the frame  12  and engage the lens  36  and the PV cells; wherein the machined single piece, or extruded waveguide, may have the same or similar refractive properties as each individual waveguide  44 . Similarly, a waveguide may be machined that runs the length  13  of the frame  12 ; wherein the single waveguide engages ten PV cells. Many other variations and dimensions of waveguides are contemplated herein and are within the scope of this disclosure. 
         [0040]    The waveguide  44  may further include legs  48  extending away from a body of the waveguide  44 . The legs  48  may extend from the proximal and distal ends of the waveguide  44 . The legs  48  may straddle the recess  16  when positioned within the cavity  32  and provide additional support to the waveguide  44  and support to the lens  36  which sits superior to the waveguide  44  when the PV module assembly  10  is assembled. 
         [0041]    Referring to  FIGS. 7 and 8 , a bracket  50  may be mounted on either side of the body  12  of the PV module assembly  10 . The bracket  50  may engage the body  12  on the width side  13  along the third wall  28  and fourth wall  30 . Each bracket  50  may resemble an S shape body in a profile view. The bracket  50  may engage the walls  28 , 30  in a number of different ways. Once such engagement means may be a releasable snap fit wherein a portion of the bracket  50  snaps over a portion of the wall  28 , 30 . A lip  52  may extend from the bracket  50  such that a force must be applied against the wall  28 , 30  with the bracket  50  to overcome the lip and engage the wall  28 , 30 . The bracket  50  may be removed when the force to overcome the lip is applied in a direction opposite the force to engage the bracket  50 . An alternate means to secure the bracket  50  may use screws and nuts or bolts. Other fastening means may also be used and are contemplated herein such as glues, adhesives, tapes, press fit, interference engagement, tabs, other threaded elements and the like. 
         [0042]    Ideally, each width side  13  of the assembly  10  may include a bracket  50 . Each bracket  50  is configured to secure the assembly to a mount such as a house a vehicle or other solar trackers which may sense and move with the light. The brackets  50  may include apertures or cutouts to allow for proper fastening of the bracket  50 , and thus the assembly  10 , to the proper location whether that be a tracker or other fixed location. The cutouts or apertures will allow for fastening mechanisms, such as screws or nuts or bolts and the like, to be passed through the cutouts or apertures to hold the assembly  10  in place on the mount. 
         [0043]    Referring to  FIGS. 9 and 10 , an alternate embodiment of a PV module assembly  110  is depicted. The assembly  110  includes a frame  112 , or body, with a length  113  and a width  115 . The frame  112  may include recesses  116  similar to the previous embodiment; however, the recesses  116  may run along the width  115  instead of the length  113  as in the previous embodiment and the recesses  116  may run parallel to each other. The recesses  116  may also run perpendicular to a first wall  118  and the second wall  120  and terminate prior to the first and second walls  118 , 120 . Each recess  116  may extend the entire width  113  of the body  112  and may run parallel to a third wall  128  and a fourth wall  130 . The number of recesses  116  may be contingent on the number of waveguides that may engage a PV cell and that may be able to be placed within the frame  112 . 
         [0044]    The current embodiment of the module  110  may include the same or similar features as the previous embodiment. The significant difference is the direction of the recesses  116  and the string of PV cells that sit within the recesses may be shorter because the direction the recesses  116  run. The number of recesses may be greater and as depicted may include thirty (30) recesses running the width  115  of the frame  112 . Because of the length of the recesses a PV cell string may be much shorter than the previous embodiment and may include three to four PV cells  8 , rather than ten PV cells  8 , strung together as set forth previously herein. 
         [0045]    The present embodiment of the assembly  110  may also include brackets  150  which may extend the length  115  of the frame  112  which is different from the previous embodiment that included brackets  50  that extended along the width  15  of the frame  12 . The brackets  150  may include the same or similar features as the previous embodiment that allow it to engage the frame  112 . 
         [0046]    Assembling the PV module assembly  10  may be automated or may be performed manually. The steps for assembling the assembly  10  may include the following: 
         [0047]    A PV cell may be cut into strips to allow those strips to reside within the recess  16  of the frame  12 . The width of those strips may be 15 mm or similar and the length may be the standard length of the standard PV cell (156 mm). The strips of the PV cell are then soldered together to form the string of PV cells  8  as disclosed herein. 
         [0048]    Forming the frame  12  as described herein wherein the frame  12 , or pan, may include a dielectric coating that at least partially covers the surface of the frame  12  or may cover the entire surface of the frame  12 . Thermally conductive tape may be applied within the recesses  16  of the frame  12  to secure the PV cells  8  to the recesses  16 . The PV cells  8  may be placed within the recesses  16  and may directly engage the conductive tape securing the string of PV cells  8  to the conductive tape and thus securing the string of PV cells  8  in the recesses  16  and thus to the frame  12 . Alternatively, thermally conductive adhesive may be applied to the cells that are secured to the recesses  16 . 
         [0049]    Each of the strings of PV cells  8  may be interconnected within the trough of the frame  12 . Each string of PV cells  8  by be connected in serious or in parallel by using crimps and/or diodes to interconnect each PV cell to the others. With all of the PV cells interconnected an external connection may be made through cord grips to the MC4 connectors or other standard electrical connectors. 
         [0050]    The aperture(s)  33  which include the vents may be disbursed on any of the side walls of the frame  12  and the water impermeable membrane is secured to the aperture(s)  33 . The vent, or water impermeable membrane, is, ideally, secured to the aperture on the internal side of the frame, or trough side; however, it may also be secured to the outside of the aperture(s)  33  depending on means of manufacture of the aperture(s)  33  and the frame  12 . 
         [0051]    The waveguide  44  may be placed onto the lens  36  and secured to the lens  36  using an adhesive. The lens may be positioned ridged, or ribbed, side up with the flat/smooth surface laying against a surface. The waveguide  44  is secured, upside down, to the lens  36  and the waveguide is secured to a ridged surface of the lens  44 . The adhesive is preferably transparent so as not to disrupt the light gathering and to optimize the amount of light passing through the lens  36  and waveguide  44 . 
         [0052]    A gel, or silicone, may be dispensed over and on top of the PV cells  8  within the recesses  16  of the frame  12 . The silicone may be a two part premixed mixture of different ratios of the components which include adhesion promoters and catalysts in addition to the silicone polymer and it covers the length of the PV cells  8  in each recess  16 . 
         [0053]    A separate adhesive, gel or silicone may be dispensed on the shoulder  22  of the frame  12 . The adhesive may hold the lens  36  in place on the shoulder  22  of the frame  22  to prevent movement of the lens  36  while also sealing the frame  12  preventing water ingress into the trough of the frame  12 . Another layer of adhesive, gel or silicone may be dispensed along the edges of the lens  36  that lies on the shoulders  22  for added security and water ingress prevention. 
         [0054]    Each of the silicones, gels or adhesives may be allowed to cure and dry and any excess may be trimmed from the frame  12 . The PV module  10  may be tested for performance after cure. In the event of any water ingress or miss performance the assembly may be disassembled in a manner reverse of assembly and the steps for assembly repeated for reassembly for a complete PV module  10 . The integrity of the sealed PV module  10  may be tested by using a vacuum pump connected to the assembly through the semi-permeable vent. 
         [0055]    Although the foregoing disclosure provides many specifics, these should not be construed as limiting the scope of any of the ensuing claims. Other embodiments may be devised which do not depart from the scopes of the claims. Features from different embodiments may be employed in combination. The scope of each claim is, therefore, indicated and limited only by its plain language and the full scope of available legal equivalents to its elements.