Patent Publication Number: US-2023163222-A1

Title: Solar cell module

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of priority to International Patent Application No. PCT/JP2021/026841, filed Jul. 16, 2021, and to Japanese Patent Application No. 2020-123958, filed Jul. 20, 2020, the entire contents of each are incorporated herein by reference. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates to a solar cell module. 
     Background Art 
     Use of solar cells as an environmentally-friendly energy source has been spreading. For example, Japanese Unexamined Patent Application, Publication No. 2017-188584 proposes a solar cell module mountable on a roof of an automobile. An automobile or the like has a limited area where solar cell modules are installed, and therefore, in order to obtain sufficient power, the solar cell modules are required to have high photoelectric conversion efficiency. In addition, it is important for an automobile or the like to have aesthetic appearance, and therefore, the solar cell modules are required to have a good design property. 
     SUMMARY 
     In the solar cell modules disclosed in Japanese Unexamined Patent Application, Publication No. 2017-188584, solar cells are held in predetermined positions by conductors connecting the solar cells and conductors connecting solar cell strings such that a front-surface plate or the like that protects a front surface is prevented from being damaged due to displacement of the solar cells. However, with such a configuration, it is difficult to arrange the solar cells with exactly equal gapes interposed therebetween. Variations in the gaps between the solar cells may cause deterioration of the design property of the solar cell modules. In view of the foregoing, the present disclosure provides a solar cell module having high photoelectric conversion efficiency and excellent aesthetic appearance. 
     A solar cell module according to one aspect of the present disclosure includes a plate-shaped front-surface protection material having, on an exterior peripheral part, a light-blocking region that blocks light, a plurality of solar cell strings each having a plurality of solar cells that are connected to each other and are aligned in line in a first direction, the plurality of solar cell strings being disposed adjacent to a back side of the front-surface protection material and aligned in a second direction intersecting with the first direction, a plate-shaped or sheet-shaped back-surface protection material disposed adjacent to back sides of the plurality of solar cell strings, and a sealing material filling a space between the front-surface protection material and the back-surface protection material. Each of the solar cell strings is disposed such that the solar cell located at at least one end of the solar cell string partially overlaps with the light-blocking region. 
     In the solar cell module, the plurality of solar cells may include a standard cell disposed at at least a location other than both ends of the solar cell string, and an end cell disposed at at least one end of the solar cell string. The end cell has a main part having a same structure as the standard cell and an extension part provided outside in the first direction of the main part and at least partially overlapping with the light-blocking region. 
     In the solar cell module, the standard cell may have a rectangular planar shape, and the end cell may have a hexagonal planar shape formed by chamfering outer corners of the extension part. 
     In the solar cell module, the standard cell may include a semiconductor substrate, a first semiconductor layer and a second semiconductor layer that are formed on a back surface of the semiconductor substrate and are different in conductivity type from each other, a first electrode pattern layered on the first semiconductor layer, and a second electrode pattern layered on the second semiconductor layer. The first semiconductor layer may include a plurality of first end semiconductor parts that extend in the first direction and are spaced apart from each other in the second direction, and a first connection semiconductor part that extends in the second direction so as to connect the plurality of first end semiconductor parts at their ends facing one side in the first direction. The second semiconductor layer may include a plurality of second end semiconductor parts that extend in the first direction and are disposed alternately with the first end semiconductor parts in the second direction, and a second connection semiconductor part that extends in the second direction so as to connect the plurality of second end semiconductor parts at their ends facing an other side in the first direction. The first electrode pattern may include a plurality of first finger electrodes that are layered on the first end semiconductor parts and extend in the first direction, and a first bus bar electrode that is layered on the first connection semiconductor part and connects the first finger electrodes at their ends facing the one side in the first direction. The second electrode pattern may include a plurality of second finger electrodes that are layered on the second end semiconductor parts and extend in the first direction, and a second bus bar electrode that is layered on the second connection semiconductor part and connects the second finger electrodes at their ends facing the other side in the first direction. 
     In the solar cell module, the first semiconductor layer of the end cell on one side in the first direction may extend to the extension part, and the second semiconductor layer of the end cell on the other side in the first direction may extend to the extension part. 
     According to the present disclosure, there can be provided a solar cell module having high photoelectric conversion efficiency and superior aesthetic appearance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a backside view illustrating a solar cell module according to one embodiment of the present disclosure; 
         FIG.  2    is a cross-sectional view taken along line X-X of an end portion of the solar cell module of  FIG.  1   ; 
         FIG.  3    is a backside view of a standard cell of the solar cell module of  FIG.  1   ; and 
         FIG.  4    is a backside view of an end cell of the solar cell module of  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. Note that the same or corresponding components in the drawings are denoted by the same reference signs. For the sake of simplification, illustrations, reference signs and the like of some of the members may be omitted from a figure, and in such a case, other figures should be referred to. The shapes and dimensions of various members in the drawings are adjusted for convenience and ease of viewing. 
       FIG.  1    is a backside view illustrating a solar cell module  1  according to one embodiment of the present disclosure.  FIG.  2    is a cross-sectional view of an end portion of the solar cell module  1 . 
     The solar cell module  1  of  FIG.  1    includes a plate-shaped front-surface protection material  10 , a plurality of solar cell strings  20  disposed adjacent to a back side (an opposite side to a side on which light is incident) of the front-surface protection material, a plate-shaped or sheet-shaped back-surface protection material  30  disposed adjacent to a back side of the plurality of solar cell strings  20 , and a sealing material  40  that fills a space between the front-surface protection material  10  and the back-surface protection material  30 . 
     The front-surface protection material  10  covers front surfaces of the solar cell strings  20  via the sealing material  40  to thereby protect the solar cell strings  20 . The front-surface protection material  10  is formed of a transparent material having scratch resistance such as glass, polycarbonate, or acrylic resin, and is preferably excellent in weather resistance. Specifically, examples of the material of the front-surface protection material  10  may include a transparent resin such as an acrylic resin or a polycarbonate resin, and glass. In order to suppress reflection of light, the front surface of the front-surface protection material  10  may have asperities formed by way of processing or may be covered with an anti-reflective coating layer. 
     The front-surface protection material  10  preferably has a thickness enough to provide a strength capable of maintaining the shape of the solar cell module  1 . By using the front-surface protection material  10  previously formed into a desired shape, the solar cell module  1  having the desired shape can be produced. 
     The front-surface protection material  10  is larger than each of the plurality of solar cell strings  20 , the back-surface protection material  30 , and the sealing material  40 , in plan view. The front-surface protection material  10  having this configuration functions as a flange for mounting the solar cell module  1  on a desired device. In other words, the solar cell module  1  can be mounted on the device by bonding, with an adhesive, the back surface of an exterior edge of the front-surface protection material  10  to the device. 
     The front-surface protection material  10  has, on an exterior peripheral part, a light-blocking region  11  that blocks light. The light-blocking region  11  is normally formed to have a constant width along the exterior edge of the front-surface protection material  10 . In a state where the solar cell module  1  is mounted on and fixed to a device via an adhesive, the light-blocking region  11  prevents the adhesive from being degraded due to sunlight irradiation through the front-surface protection material  10 . In addition, the light-blocking region  11  covers and conceals the mounting part of the solar cell module  1  to thereby improve the aesthetic appearance. The light-blocking region  11  can be formed by applying a black paint, for example. As the black paint, a ceramic paint is generally used. 
     The solar cell strings  20  each include a plurality of solar cells (standard cells  21 A disposed at locations other than both ends of the solar cell string  20  and end cells  21 B disposed at both ends of the solar cell string) that are connected to each other and are aligned in line in a first direction. The solar cell strings  20  are disposed adjacent to the back side of the front-surface protection material  10  and aligned in a second direction intersecting with the first direction. In each of the solar cell strings  20 , the solar cells  21 A,  21 B adjacent to each other are connected by inter connectors  22 . The plurality of solar cell strings  20  are connected by wiring materials  23  via the inter connectors  22 . In addition, the solar cell strings  20  are each disposed so that a portion of the end cell  21 B at each end overlaps with the light-blocking region  11 . Thus, each solar cell string  20  has a continuous effective region where photoelectric conversion is enabled, over the entire length in the first direction of a region inside the light-blocking region  11 , thereby making the solar cell module  1  have relatively high photoelectric conversion efficiency. 
     The standard cell  21 A includes a semiconductor substrate  211 , a first semiconductor layer  212  and a second semiconductor layer  213  that are formed on the back surface of the semiconductor substrate  211  and are different in conductivity type from each other, a first electrode pattern  214  layered on the first semiconductor layer  212 , and a second electrode pattern  215  layered on the second semiconductor layer  213 . 
     In planar view, the semiconductor substrate  211  of the standard cell  21 A, i.e., the standard cell  21 A has a rectangular shape. The semiconductor substrate  211  can be formed from a crystalline silicon material such as single crystal silicon or polycrystalline silicon. Alternatively, the semiconductor substrate  211  may be formed from other semiconductor materials such as gallium arsenic (GaAs). The semiconductor substrate  211  is, for example, an n-type semiconductor substrate including a crystalline silicon material doped with an n-type dopant. The n-type dopant may be, for example, phosphorus (P). The semiconductor substrate  211  functions as a photoelectric conversion substrate to generate photocarriers (electrons and holes) when absorbing light incident on a light receiving surface. When the semiconductor substrate  211  is made of crystalline silicon, a dark current can be kept relatively low, and relatively high power (stable power regardless of illumination intensity) can be obtained even if the incident light has low intensity. 
     The first semiconductor layer  212  and the second semiconductor layer  213  have different conductivity types from each other. The first semiconductor layer  212  and the second semiconductor layer  213  generate a large number of carriers different from each other to thereby form an electrical field for attracting the carriers generated by the semiconductor substrate  211 . 
     Specifically, the first semiconductor layer  212  is formed from a p-type semiconductor, and the second semiconductor layer  213  is formed from an n-type semiconductor. The first semiconductor layer  212  and the second semiconductor layer  213  each can be formed from, for example, an amorphous silicon material containing a dopant imparting a desired conductivity type. A p-type dopant may be, for example, boron (B), and an n-type dopant may be, for example, phosphorus (P) described above. 
     As shown in detail in  FIG.  3   , the first semiconductor layer  212  includes a plurality of first end semiconductor parts  2121  that extend in the first direction and are spaced apart from each other in the second direction intersecting the first direction, and a first connection semiconductor part  2122  that extends in the second direction so as to connect the plurality of first end semiconductor parts  2121  at their ends facing one side in the first direction. The second semiconductor layer  213  includes a plurality of second end semiconductor parts  2131  that extend in the first direction and are disposed alternately with the first end semiconductor parts  2121  in the second direction, and a second connection semiconductor part  2132  that extends in the second direction so as to connect the plurality of second end semiconductor parts  2131  at their ends facing the other side in the first direction. 
     The first electrode pattern  214  is provided to extract the electric charges from the first semiconductor layer  212 , and the second electrode pattern  215  is provided to extract the electric charges from the second semiconductor layer  213 . The first electrode pattern  214  and the second electrode pattern  215  are layered while margins are left in the exterior edges of the first semiconductor layer  212  and the second semiconductor layer  213  such that a short circuit is prevented. The first electrode pattern  214  and the second electrode pattern  215  may be formed by means of, for example, etching of a metal layer or printing and baking of the conductive paste. Alternatively, the first electrode pattern  214  and the second electrode pattern  215  may be laminates that are layered on the first semiconductor layer  212  and the second semiconductor layer  213 , respectively, and that each includes a transparent electrode layer made of, for example, indium tin oxide (ITO) or zinc oxide (ZnO), and a metal electrode layer including a metal as a main constituent. 
     Specifically, the first electrode pattern  214  includes a plurality of first finger electrodes  2141  that are layered on the first end semiconductor parts  2121  and extend in the first direction, and a first bus bar electrode  2142  that is layered on the first connection semiconductor part  2122  and connects the first finger electrodes  2141  at their ends facing the one side in the first direction. The second electrode pattern  215  includes a plurality of second finger electrodes  2151  that are layered on the second end semiconductor parts  2131  and extend in the first direction, and a second bus bar electrode  2152  that is layered on the second connection semiconductor part  2132  and connects the second finger electrodes  2151  at their ends facing the other side in the first direction. The first bus bar electrode  2142  and the second bus bar electrode  2152  have widths greater than the widths of the first finger electrode  2141  and the second finger electrode  2151 , and are also used as terminals to which the inter connectors  22  are connected so as to output electric power from the standard cell  21 A. 
     As shown in  FIG.  4   , the end cell  21 B includes a main part  21 B 1  having the same structure as the standard cell  21 A, and an extension part  21 B 2  that is provided outside in the first direction of the main part  21 B 1  and at least partially overlaps with the light-blocking region  11  (the one-dot chain line in  FIG.  4    indicates a boundary between the main part  21 B 1  and the extension part  21 B 2 ). The extension part  21 B 2  is formed by extending a portion toward outside in the first direction of the semiconductor substrate  211  forming the main part  21 B 1 , and a portion toward outside in the first direction of the first connection semiconductor part  2122  or the second connection semiconductor part  2132  of the main part  21 B 1 . Specifically, the first semiconductor layer  212  of the end cell  21 B on the one side in the first direction extends to the extension part  21 B 2 , while the second semiconductor layer  213  of the end cell  21 B on the other side in the first direction extends to the extension part  21 B 2 . 
     In the solar cell string  20 , the extension parts  21 B 2  of the end cells  21 B are prevented from receiving light by the light-blocking region  11 , which makes the end cells  21 B partially unable to contribute to the photoelectric conversion, whereas the main parts  21 B 1  are not prevented from receiving light by the light-blocking region  11 , which makes it possible for the end cells  21 B to output substantially same amount of electric power as the standard cells  21 A. Accordingly, in the solar cell string  20 , the outputs of all the solar cells  21 A,  21 B are substantially equal to each other, and therefore the solar cell string  20  as a whole is excellent in the photoelectric conversion efficiency. 
     The standard cells  21 A and the end cells  21 B may be formed by dividing a semiconductor wafer into a plurality of pieces in the first direction. The extension part  21 B 2  of the end cell  21 B can be formed of an end region of the semiconductor wafer. Accordingly, the end cell  21 B has a hexagonal planar shape formed by chamfering outer corners of the extension part  21 B 2 , whereby the use efficiency of the semiconductor wafer can be improved. In addition, the standard cell  21 A is obtained by cutting off the extension part  21 B 2  from the end cell  21 B, and therefore, the number of standard cells  21 A and the number of end cells  21 B can be easily adjusted according to a configuration of the solar cell string  20 . 
     The lower limit of the length in the first direction of the extension part  21 B 2  is preferably 1 mm, and more preferably 3 mm. On the other hand, the upper limit of the length in the first direction of the extension part  21 B 2  is preferably 20 mm, and more preferably 15 mm Setting the length in the first direction of the extension part  21 B 2  to the above-described lower limit or more makes it possible to efficiently prevent the aesthetic appearance from being degraded due to positional errors of the solar cell strings  20  that can be caused at the time of assembling the solar cell module  1 . Setting the length in the first direction of the extension part  21 B 2  to the above-described upper limit or less makes it possible to achieve a relatively high use efficiency of the semiconductor wafer when the solar cells  21 A and  21 B are produced. 
     The back-surface protection material  30  is a layer that protects the back sides of the solar cell strings  20 . The back-surface protection material  30  may be made of any material, but is preferably made of a material capable of preventing infiltration of water and the like (highly water-impermeable material). Specifically, the back-surface protection material  30  may be made of, for example, glass, or a resin such as polyethylene terephthalate (PET), an acrylic resin, polyethylene (PE), an olefin resin, a fluorine-containing resin, or a silicone-containing resin. Alternatively, the back-surface protection material  30  may be a laminate of a resin layer and a metal layer such as an aluminum foil. The color (light reflection characteristics) of the back-surface protection material  30  as viewed from the front side surface is preferably approximate to the color of the front side surfaces of the solar cells  21 A,  21 B such that gaps between the solar cell strings  20  are made inconspicuous, thereby improving the aesthetic appearance of the solar cell module  1 . 
     The sealing material  40  seals the solar cell strings  20  in the space between the front-surface protection material  10  and the back-surface protection material  30 , thereby suppressing the degradation of the solar cell strings  20  due to moisture or the like. The sealing material  40  is formed from a transparent material having adhesiveness to the front-surface protection material  10  and the solar cell strings  20 . The material of the sealing material  40  preferably has thermoplasticity so that the space between the front-surface protection material  10  and the solar cell strings  20  can be sealed by heat pressing. Specifically, examples of the material of the sealing material  40  include a resin composition containing, as a main component, ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, ethylene-vinyl acetate-triallyl isocyanurate (EVAT), polyvinyl butyrate (PVB), an acrylic resin, a urethane resin, or a silicone resin. 
     While an embodiment of the present disclosure has been described in the foregoing, the above embodiment is not intended to limit the present disclosure and may be altered or modified in various ways. For example, a specific structure of the solar cells in the solar cell module according to the present disclosure, such as the planar shapes of the semiconductor layer and the electrode pattern, may be different from those of the above embodiment. Alternatively, the solar cell strings may include solar cells all having the same structure. 
     In the solar cell module according to the present disclosure, each solar cell string may have only one end overlapping with the light-blocking region. Accordingly, the solar cell string of the solar cell module according to the present disclosure may include, at only one end, the end cell having the extension part. 
     In the solar cell module according to the present disclosure, the back-surface protection material and the sealing material may have the same planar shape as the front-surface protection material. In particular, in a case where the back-surface protection material is formed from a rigid material such as glass, the exterior edge of the back-surface protection material may be bonded to a frame of an automobile or the like with an adhesive.