Abstract:
A photovoltaic energy panel has first and second electrically conductive regions on first and second sides of an electrically insulating sheet. Each of at least some pairs of the first electrically conductive regions are connected electrically by a photovoltaic cell between the two members of the pair. The panel also includes vias, each of which electrically connects one of the first electrically conductive regions to one of the second electrically conductive regions. There are first and electrical contacts, at first and second edges of the sheet, each of which is directly or indirectly connected to one of the electrically conductive regions. The electrically conductive regions, the cells and the vias are arranged to provide an electrically conductive path between one of the first contact and one, two or more of the second contacts.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to photovoltaic energy panels and, more particularly, to a photovoltaic energy panel based on an innovative electrical circuit. 
         [0002]    Background information on photovoltaic energy panels may be found in the following US patent documents: 
         [0003]    U.S. Pat. No. 3,369,939 to Myer 
         [0004]    U.S. Pat. No. 3,427,200 to Lapin et al. 
         [0005]    U.S. Pat. No. 3,574,925 to Schneider et al. 
         [0006]    U.S. Pat. No. 4,023,368 to Kelly 
         [0007]    U.S. Pat. No. 4,088,121 to Lapeyre 
         [0008]    U.S. Pat. No. 4,089,705 to Rubin 
         [0009]    U.S. Pat. No. 4,166,917 to Dorfeld et al. 
         [0010]    U.S. Pat. No. 4,174,978 to Lidorenko et al. 
         [0011]    U.S. Pat. No. 4,350,836 to Crouthamel et al. 
         [0012]    U.S. Pat. No. 4,367,367 to Reisfeld et al. 
         [0013]    U.S. Pat. No. 5,374,317 to Lamb et al. 
         [0014]    U.S. Pat. No. 6,493,342 to Bechtel et al. 
         [0015]    U.S. Pat. No. 7,161,083 to Mortenson 
         [0016]    U.S. Pat. No. 8,067,295 to Yagiura et al. 
         [0017]    U.S. Pat. No. 2012/0024345 to Reisfeld et al. 
         [0018]    All of these patent documents are incorporated by reference for all purposes as if fully set forth herein. 
         [0019]    Moslehi, in U.S. Pat. No. 8,035,028, which also is incorporated by reference for all purposes as if fully set forth herein, teaches a photovoltaic energy panel based on thin film solar cells that are mounted on a printed circuit board.  FIG. 1  is  FIG. 59  of the Moslehi patent and shows an array  980  of thin film solar cells  982  connected in series and connecting an input lead  984  to an output lead  986 . Array  980  is mounted on a printed circuit board.  FIG. 2  is  FIG. 60  of the Moslehi patent and shows the upper surface  990  of the printed circuit board, with electrically conductive solid squares  992  and electrically conductive hollow squares  994 .  FIG. 3  is  FIG. 61  of the Moslehi patent and shows the lower surface  1000  of the printed circuit board with electrically conductive regions that are connected to squares  992  and  994 , by vias that are represented by small circles, to provide the series connection that is illustrated in  FIG. 1 . 
         [0020]      FIG. 4  illustrates the principle of concentration of solar energy by a luminescent solar concentrator  10 . Luminescent solar concentrator  10  is a transparent glass or plastic plate that is doped with luminophores  12 . A photovoltaic cell  14  is mounted on the side of concentrator  10 . Luminophores  12  absorb incident solar radiation  16  at wavelengths that are too short for cell  14  to convert efficiently to direct current (DC) electricity and re-radiate the radiation at wavelengths that cell  14  converts more efficiently to DC electricity. Concentrator  10  acts as a waveguide that conveys the re-radiated radiation, as well as directly incident radiation  16 , to cell  14 . 
         [0021]    A sufficient number of breaks in the electrical connections from upper surface  990  of Moslehi&#39;s printed circuit board to lower surface  1000  of Moslehi&#39;s printed circuit board, for example in the vias that connect one of hollow squares  994  to the corresponding electrically conductive region on lower surface  1000 , can render array  980  inoperative. Moslehi states, without showing explicitly how, that solar cells  982  can be connected in a mixed series-parallel circuit, which presumably would be more robust against such failures that the strictly series circuit of  FIGS. 1-3 ; but a sufficient number of breaks in the electrical connections to input lead  984  or output lead  986  still would render such a serial-parallel array of solar cells  982  inoperative. It would be highly advantageous to have a photovoltaic energy panel that is more robust against failure than the photovoltaic energy panels of Moslehi. 
       SUMMARY OF THE INVENTION 
       [0022]    According to the present invention there is provided an electrical device including: (a) an electrically insulating sheet; (b) on a first side of the sheet: (i) a plurality of first electrically conductive regions that are electrically isolated from each other, and (ii) for each of at least a portion of adjacent pairs of the first electrically conductive regions: a respective electrical component that electrically connects the first electrically conductive regions of the each pair; (c) on a second side of the sheet, a plurality of second electrically conductive regions that are electrically isolated from each other; (d) a plurality of vias through the sheet, each via electrically connecting one respective the first electrically conductive region to one the second electrically conductive region; (e) at least one first electrical contact, at a first edge of the sheet, electrically connected to one of the electrically conductive region; and (f) a plurality of second electrical contacts at a second edge of the sheet, each second electrical contact being electrically connected to one of the electrically conductive regions; wherein the electrically conductive regions, the components and the vias are arranged to provide an electrically conductive path between each first electrical contact and at least two of the second electrical contacts. 
         [0023]    According to the present invention there is provided a photovoltaic energy panel including: (a) an electrically insulating sheet; (b) on a first side of the sheet: (i) a plurality of first electrically conductive regions that are electrically isolated from each other, and (ii) for each of at least a portion of adjacent pairs of the first electrically conductive regions: a respective photovoltaic cell, between the first electrically conductive regions of the each pair, that electrically connects the first electrically conductive regions of the each pair; (c) on a second side of the sheet, a plurality of second electrically conductive regions that are electrically isolated from each other; (d) a plurality of vias through the sheet, each via electrically connecting one respective the first electrically conductive region to one the second electrically conductive region; (e) at least one first electrical contact, at a first edge of the sheet, electrically connected to one of the electrically conductive region; and (f) at least one IS second electrical contact at a second edge of the sheet, electrically connected to one of the electrically conductive regions; wherein the electrically conductive regions, the photovoltaic cells and the vias are arranged to provide an electrically conductive path between each first electrical contact and at least one of the at least one second electrical contact. 
         [0024]    According to the present invention there is provided a photovoltaic energy panel including: (a) a substantially flat substrate; (b) at least one photovoltaic cell embedded in the substrate; (c) an optically transparent layer covering at least a portion of the substrate; and (d) for each photovoltaic cell, a respective lens for directing, towards the each photovoltaic cell, light that emerges from the optically transparent layer. 
         [0025]    A basic embodiment of an electrical device is based on an electrically insulating sheet. On a first side of the sheet there is a plurality of first electrically conductive regions that are electrically isolated from each other. For at least some adjacent pairs of such first electrically conductive regions, there is a respective electrical component, such as a photovoltaic cell, that electrically connects the two members of the pair. On a second side of the sheet there is a plurality of second electrically conductive regions that are electrically isolated from each other. Through the sheet there are vias, each one of which electrically connects one of the first electrically conductive regions to one of the second electrically conductive regions. There is at least one electrical contact, at a first edge of the sheet (i.e., off to the side of the electrically conductive regions on that side of the sheet), that is electrically connected to one of the electrically conductive regions, either directly to one of the electrically conductive regions on that side of the sheet or by a via to one of the electrically conductive regions on the other side of the sheet. There is a plurality of electrical contacts, at a second edge of the sheet (i.e., off to the side of the electrically conductive regions on that side of the sheet), each of which is electrically connected to one of the electrically conductive regions, either directly to one of the electrically conductive regions on that side of the sheet or by a via to one of the electrically conductive regions on the other side of the sheet. The electrically conductive regions, the components and the vias are arranged to provide an electrically conductive path between each first electrical contact and at least two of the second electrical contacts. 
         [0026]    Preferably, the device includes a plurality of first electrical contacts. 
         [0027]    Preferably, if the components are photovoltaic cells, each cell is between the two first electrically conductive regions that are electrically connected by the cell. Also, if the components are photovoltaic cells, the device preferably also includes an optically transparent layer that covers at least a portion of the first electrically conductive regions on the first side of the sheet, and also includes, for each cell, a respective lens for directing, towards that cell, light that emerges from the optically transparent layer. Most preferably, such a device also includes a diffusely reflective layer, that at least partially covers the first electrically conductive regions, between the first side of the sheet and the optically transparent layer. Also most preferably, the transparent layer includes a luminescent solar concentrator. 
         [0028]    A basic embodiment of a photovoltaic energy panel is based on an electrically insulating sheet. On a first side of the sheet there is a plurality of first electrically conductive regions that are electrically isolated from each other. At least some adjacent pairs of such first electrically conductive regions have, between the two members of the pair, a respective photovoltaic cell that electrically connects the two members of the pair. On a second side of the sheet there is a plurality of second electrically conductive regions that are electrically isolated from each other. Through the sheet there are vias, each one of which electrically connects one of the first electrically conductive regions to one of the second electrically conductive regions. There is at least one electrical contact, at a first edge of the sheet (i.e., off to the side of the electrically conductive regions on that side of the sheet), that is electrically connected to one of the electrically conductive regions, either directly to one of the electrically conductive regions on that side of the sheet or by a via to one of the electrically conductive regions on the other side of the sheet. There is at least one electrical contact, at a second edge of the sheet (i.e., off to the side of the electrically conductive regions on that side of the sheet), that is electrically connected to one of the electrically conductive regions, either directly to one of the electrically conductive regions on that side of the sheet or by a via to one of the electrically conductive regions on the other side of the sheet. The electrically conductive regions, the cells and the vias are arranged to provide an electrically conductive path between each first electrical contact and (at least one of) the second electrical contact(s). 
         [0029]    Preferably, the panel also includes an optically transparent layer that covers at least a portion of the first electrically conductive regions on the first side of the sheet, and also includes, for each cell, a respective lens for directing, towards that cell, light that emerges from the optically transparent layer. Most preferably, such a panel also includes a diffusely reflective layer, that at least partially covers the first electrically conductive regions, between the first side of the sheet and the optically transparent layer. Also most preferably, the transparent layer includes a luminescent solar concentrator. 
         [0030]    Another basic photovoltaic energy panel includes a substantially flat substrate, one or more photovoltaic cells embedded in the substrate, an optically transparent layer that covers at least a portion of the substrate, and, for each cell, a respective lens that directs, towards the cell, light that emerges from the optically transparent layer. 
         [0031]    Preferably, the optically transparent layer includes a luminescent solar concentrator. 
         [0032]    Preferably, the panel also includes a diffusely reflective layer between the substrate and the optically transparent layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    Various embodiments are herein described, by way of example only, with reference to the accompanying drawings, wherein: 
           [0034]      FIG. 1  shows a solar panel of the prior art that includes an array of thin film solar cells mounted on a printed circuit board; 
           [0035]      FIG. 2  shows the upper surface of the printed circuit board of the solar panel of  FIG. 1 ; 
           [0036]      FIG. 3  shows the lower surface of the printed circuit board of the solar panel of  FIG. 1 ; 
           [0037]      FIG. 4  illustrates the principle of concentration of solar energy by a luminescent solar concentrator; 
           [0038]      FIGS. 5 and 6  are cross-sections of small portions of two different photovoltaic panels of the present invention; 
           [0039]      FIG. 7  shows the layout of the upper conductors of a basic photovoltaic panel of the present invention; 
           [0040]      FIGS. 8A and 8B  show the layout of the lower conductors of a basic photovoltaic panel of the present invention; 
           [0041]      FIGS. 9A and 9B  show a portion of the layout of a typical full-size photovoltaic panel of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    The principles and operation of a photovoltaic panel according to the present invention may be better understood with reference to the drawings and the accompanying description. 
         [0043]    Referring again to the drawings,  FIG. 5  is a cross-section of a small portion of a photovoltaic panel  20  of the present invention. Photovoltaic panel  20  is based on a planar, electrically insulating substrate sheet  22  that preferably is made of epoxy. Electrical conductors such as copper are plated by standard printed circuit board fabrication techniques on the two sides of substrate  22 : upper conductors  24  on the upper side of substrate  22  and lower conductors  26  on the lower side of substrate  26 . Upper conductors  24  and lower conductors  26  are connected electrically by way of vias  36  through substrate  22 . A photovoltaic cell  28 , with the indicated polarity, is placed in a trench in substrate  22  between two upper conductors  24  and in electrical contact with those two upper conductors  24 . Preferably, photovoltaic cell  28  is a monocrystalline silicon photovoltaic cell with a surface such as a black silicon surface for efficient absorption of incident light. When photovoltaic cell  28  is illuminated with light of the appropriate wavelengths, photovoltaic cell  28  creates a voltage difference between the two upper conductors  24  that causes an electrical current to flow through the two upper conductors  24 . 
         [0044]    Upper conductors  24  are covered by a thin layer  30  of a diffusively reflective material that in turn is covered by a luminescent solar concentrator  32  that butts up against photovoltaic cell  28  the way luminescent solar concentrator  10  of  FIG. 4  butts up against photovoltaic cell  14  of  FIG. 4 . 
         [0045]      FIG. 6  is a cross-section of a small portion of another photovoltaic panel  21  of the present invention. Photovoltaic panel  21  is similar to photovoltaic panel  20 , with photovoltaic cell  28  oriented horizontally instead of vertically. A pyrimidal lens  34  is provided above photovoltaic cell  28  to direct light from luminescent solar concentrator  32  down towards photovoltaic cell  28 . Photovoltaic cell  28  is encapsulated in an electrically conductive encapsulation.  38  and is separated from lens  34  by vacuum  40 . 
         [0046]      FIGS. 7 and 8A  show, respectively, the layout of upper conductors  24  and lower conductors  26  in a basic photovoltaic panel  20  or  21  of the present invention. There are two kinds of upper conductors  24 : triangular petals of three hexagonal flowers, and, rectangles that surround the array of the three flowers. The sides of the hexagons are about 5 cm long_ 45  photovoltaic cells  28 , labeled “ 28 - 1 ” through “ 28 - 45 ”, are positioned between the hexagons and between the hexagons and the rectangles, as shown. The unlabeled circles in  FIG. 7  represent vias  36  that connect upper conductors  24  to lower conductors  26 . Lower conductors  26  are shaped so as to connect photovoltaic cells  28  in series in a manner that provides the following paths from a contact  42 A adjacent to lower conductors  26  at one edge of substrate  22  to a contact  42 B adjacent to lower conductors  26  at the opposite edge of substrate  22 : 
         [0047]    First path: ( 28 - 1 ), ( 28 - 2 ), ( 28 - 3 ), ( 28 - 4 ), ( 28 - 5 ), ( 28 - 6 ), ( 28 - 19 ), ( 28 - 20 ), ( 28 - 21 ), ( 28 - 22 ), ( 28 - 23 ), ( 28 - 24 ), ( 28 - 25 ), ( 28 - 26 ), ( 28 - 27 ) 
         [0048]    Second path: ( 28 - 1 ), ( 28 - 2 ), ( 28 - 3 ), ( 28 - 4 ), ( 28 - 5 ), ( 28 - 6 ), ( 28 - 7 ), ( 28 - 8 ), to ( 28 - 9 ), ( 28 - 28 ), ( 28 - 29 ), ( 28 - 30 ), ( 28 - 31 ), ( 28 - 32 ), ( 28 - 33 ) 
         [0049]    Third path: ( 28 - 10 ), ( 28 - 11 ), ( 28 - 12 ), ( 28 - 13 ), ( 28 - 14 ), ( 28 - 15 ), ( 28 - 16 ), ( 28 - 17 ), ( 28 - 18 ), ( 28 - 28 ), ( 28 - 29 ), ( 28 - 30 ), ( 28 - 31 ), ( 28 - 32 ), ( 28 - 33 ) 
         [0050]    and from contact  42 A to another contact  42 C adjacent to lower conductors  26  at the opposite edge of substrate  22 : 
         [0051]    Fourth path: ( 28 - 10 ), ( 28 - 11 ), ( 28 - 12 ), ( 28 - 13 ), ( 28 - 14 ), ( 28 - 15 ), ( 28 - 37 ), ( 28 - 38 ), ( 28 - 39 ), ( 28 - 40 ), ( 28 - 41 ), ( 28 - 42 ), ( 28 - 43 ), ( 28 - 44 ), ( 28 - 45 ) 
         [0052]    Fifth path: ( 28 - 10 ), ( 28 - 11 ), ( 28 - 12 ), ( 28 - 13 ), ( 28 - 14 ), ( 28 - 15 ), ( 28 - 16 ), ( 28 - 17 ), ( 28 - 18 ), ( 28 - 28 ), ( 28 - 29 ), ( 28 - 30 ), ( 28 - 34 ), ( 28 - 35 ), ( 28 - 36 ) 
         [0053]    Sixth path: ( 28 - 1 ), ( 28 - 2 ), ( 28 - 3 ), ( 28 - 4 ), ( 28 - 5 ), ( 28 - 6 ), ( 28 - 7 ), ( 28 - 8 ), ( 28 - 9 ), ( 28 - 28 ), ( 28 - 29 ), ( 28 - 30 ), ( 28 - 34 ), ( 28 - 35 ), ( 28 - 36 ) 
         [0054]      FIG. 8B  shows the structure of lower conductors  26 , as designed using standard computer-aided-design software: lower conductors  26  are individual triangular petals, similar to upper conductors  24 , or pairs of such triangular petals, extended and/or joined by jumpers that appear in  FIG. 8B  as ovals that have circles at both ends. 
         [0055]    Lower conductors  26  connect the negative side of each photovoltaic cell  28  in each path (except for the last photovoltaic cell  28  in the path) to the positive side of the next photovoltaic cell in the path, as shown by the “+” signs in  FIGS. 8A and 8B , so that the voltages generated by photovoltaic cells  28  are added to each other along the paths. In the case of  FIGS. 7 ,  8 A and  8 B, with 15 photovoltaic cells  28  in each path, the total voltage difference between contact  42 A and either contact  42 B or contact  42 C is 15 times the voltage produced by one photovoltaic cell  28 , minus resistive losses in conductors  24  and  26  and in vias  36 . The electrical power generated by the photovoltaic panel is tapped via leads  44 . Normally, a lead  44  is provided between adjacent pairs of contacts  42 , as shown in  FIG. 8A  for contacts  42 B and  42 C. 
         [0056]    In addition to providing the electrical connections among photovoltaic cells  28 , conductors  24  and  26  also conduct heat away from photovoltaic cells  28  to keep photovoltaic cells  28  from overheating. To this end, preferably, conductors  24  and  26  are made of a material such as copper that is both an excellent electrical conductor and an excellent thermal conductor. 
         [0057]      FIGS. 9A and 9B  show a portion of the layout of a typical full-size photovoltaic panel  20  or  21  of the present invention.  FIGS. 9A and 9B  show all or part of  39  hexagons labeled “A1” through “F6”, bounded by (unlabeled) photovoltaic cells  28 , and the associated leads  44  shown as black squares. The circles in the middle of the hexagons are test points for testing the connectivity of conductors  24  and  26 . There are many more conductive paths from a contact at one edge  46 A of such a panel to contacts at the opposite edge  46 B of such a panel, as shown by the thick lines in  FIG. 9B , than there are in the basic panel of  FIGS. 7 ,  8 A and  8 B 
         [0058]    A 36-hexagon panel (area of about 0.25 meters) (similar to  FIG. 9A  but without the hexagons labeled “A7”, “C7” and “E7”), either with vertical photovoltaic cells (panel  20 ) or with horizontal photovoltaic cells (panel  21 ), when illuminated by full sunshine, produces about 80-100 watts of DC power (about 24 volts across the panel; current of about 4 amps). 
         [0059]    While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. Therefore, the claimed invention as recited in the claims that follow is not limited to the embodiments described herein.