Patent Publication Number: US-2013247963-A1

Title: Solar cell module and manufacturing method therefor

Description:
FIELD OF THE INVENTION 
     The present invention relates to a solar cell module and a method for manufacturing the same. 
     BACKGROUND 
     In recent years solar cell modules have attracted a great amount of attention as energy sources with low environmental impact. 
     Solar cell modules are provided with solar cells. Solar cells are easily degraded through contact with moisture and the like. Therefore, solar cells must be isolated from outside air. Therefore, solar cells are normally disposed within filler layers that are provided between protective members to protect the front and back. 
     With regard to these filler layers, for example, Patent Reference 1 described below states that, of these filler layers, a portion positioned between the back surface of a solar cell and the back surface side protective member is fabricated of a colored EVA film. In addition, Patent Reference 1 states that photoelectric conversion efficiency can be improved because the utilization efficiency of light is increased by using the colored EVA film. 
     DOCUMENTS OF PRIOR ART 
     [Patent Documents] 
     Patent Reference 1: Published Unexamined Patent Application No. 2003-258283 
     SUMMARY 
     Problems to be Solved by the Invention 
     The solar cell module described in Patent Reference 1 can be manufactured by, for example, thermocompression bonding of a laminate in which solar cells are disposed between a colored EVA film and a transparent EVA film. 
     However, when the solar cell module described in Patent Reference 1 is manufactured by this manufacturing method, there is concern that the colored EVA will wrap around to the light receiving surface side of the solar cells. If the colored EVA wraps around to the light receiving surface side of the solar cells, part of the light that should be incident to the light receiving surface will be shielded by the colored EVA. Therefore, the output of the solar cell module will be reduced because the light reception efficiency on the light receiving surface is reduced. 
     Means to Solve the Problems 
     A solar cell module according to an embodiment of the present invention has a colored resin layer and a transparent resin layer laminated on top of the colored resin layer. The solar cells are disposed between the colored resin layer and the transparent resin layer with the back surface oriented to the colored resin layer side and the light receiving surface oriented toward the transparent resin layer side. The solar cell module according to the present invention has bonding by a silane coupling agent between the light receiving surface of the solar cells and the transparent resin layer. 
     A manufacturing method for a solar cell module according to an embodiment of the present invention relates to a manufacturing method for the solar cell module having a colored resin layer and a transparent resin layer. The transparent resin layer is laminated on top of the colored resin layer. Solar cells are disposed at the boundary between the colored resin layer and transparent resin layer with the back surface oriented toward the loop resin layer side and the light receiving surface oriented toward the transparent resin layer side. The manufacturing method for the solar cell module according to an embodiment of the present invention has a silane coupling agent applied to at least one of a transparent resin sheet for constituting the transparent resin layer and the light receiving surface of solar cells. The transparent resin sheet, solar cells, and a colored resin sheet for constituting the colored resin layer are laminated such that the light receiving surface of the solar cells is in contact with one main surface of the transparent resin sheet while the back surface is in contact with the colored resin sheet, and a laminate is fabricated. Thermocompression bonding is carried out to thermocompression bond the laminate. 
     EFFECTS OF THE INVENTION 
     According to the present invention, a solar cell module having improved output and a method that can manufacture that solar cell module are provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view of a solar cell module according to an embodiment of the present invention. 
         FIG. 2  is a schematic cross-sectional view for describing a manufacturing method for the solar cell module according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following, an example of a preferred embodiment of the present invention will be described. However, the embodiment described below is only an example. The present invention is not limited in any manner to the following embodiment. 
     In addition, in the drawings referred to in the following embodiment, members having substantially the same function are referred to by the same element numbers. In addition, the figures referred to in the embodiment are denoted schematically, and the proportions of dimensions of objects drawn in the drawings and the like may differ from the proportions of dimensions of actual objects. The dimensional proportions and the like of objects may also differ among the drawings. Specifically, dimensional proportions and the like of objects should be judged with allowance made for the following description. 
       FIG. 1  is a schematic cross-sectional view of the solar cell module according to the present embodiment. 
     A solar cell module  1  comprises a first protective member  10 , a second protective member  11 , a filler layer  13  as a resin layer, and solar cell strings  15 . 
     The solar cell module  1  may have a frame that surrounds the periphery thereof. In addition, there may be a terminal box for extracting electric power on a front surface of a second protective member  12 . 
     (Light Receiving Surface Side Protective Member  10  and Back Surface Side Protective Member  11 ) 
     The first protective member  10  is disposed on the light receiving surface of the solar cell module  1 . The first protective member  10  is a member that secures mechanical strength for the solar cell module  1 . Therefore, the protective member  10  is preferably a member having transparency and rigidity. The protective member  10  can be constituted of a glass sheet, resin sheet, or the like. Among these, the protective member  10  is preferably constituted of a glass sheet. This is because a glass plate has high rigidity and light transmission as well as superior weatherability. The thickness of the first protective member  10  is not limited in particular. The thickness of the protective member  10  is, for example, when a glass sheet is used, roughly 3 mm-6 mm. 
     The second protective member  11  faces the first protective member  10 . The second protective member  11  is disposed on the back surface of the solar cell module  1 . The second protective member  11  can, for example, be constituted of a resin sheet formed from polyethylene terephthalate (PET) or the like. Moreover, within the resin sheet constituting the protective member  11 , for example, a metal foil such as aluminum foil, an inorganic barrier layer with low moisture permeability, or the like may be provided. The inorganic barrier layer can, for example, be formed of an inorganic oxide such as silicon oxide, aluminum oxide, magnesium oxide, and the like. Moreover, the thickness of the second protective member  11  is not limited in particular. The thickness of the protective member  11  can be, for example, when a resin sheet is used, roughly 150 μm-300 μm. 
     (Solar Cell Strings  15 ) 
     A plurality of solar cell strings  15  is disposed within the filler layer  13 . Specifically, the solar cell strings  15  are provided with a plurality of solar cells  12 . The plurality of solar cells  12  is arranged in one direction and is electrically connected in series or parallel by wiring material  14 . Specifically, the plurality of solar cells  12  are electrically connected in series or parallel by the solar cells  12  that are arranged in a single direction and adjacent to each other being electrically connected by the wiring material  14 . In the present embodiment, the wiring material  14  electrically connects an electrode disposed on a light receiving surface  12   a  of one of the solar cells  12  that are adjacent to each other and an electrode disposed on a back surface  12   b  of the other. 
     Moreover, in the present invention, the solar cells may be back surface joining type solar cells in which both a p side electrode and an n side electrode are disposed on the back surface. In such a case, the wiring material  14  electrically connects the p side electrode on one solar cell of solar cells that are adjacent to each other and the n side electrode on the other solar cell. 
     (Filler Layer  13 ) 
     The filler layer  13  is filled in between the first protective member  10  and the second protective member  11 . A plurality of solar cell strings  15  is disposed within the filler layer  13 . In other words, the filler layer  13  is a member for sealing the solar cell strings  15 . Therefore, the filler layer  13  may also be referred to as a sealing layer. 
     Specifically, the filler layer  13  is constituted of a laminate that includes a colored resin layer  13   a  and a transparent resin layer  13   b . The colored resin layer  13   a  is disposed on the second protective member  11  side of the solar cells  12 . The transparent resin layer  13   b  is disposed on the first protective member  10  side of the solar cells  12 . In the solar cell module  1 , the colored resin layer  13   a , and the transparent resin layer  13   b  are disposed so as to be adjacent to each other. The solar cell strings  15  are disposed in the interface between the colored resin layer  13   a  and the transparent resin layer  13   b . The solar cell strings  15  are disposed such that a light receiving surface  12   a  is oriented toward the transparent resin layer  13   b  side and a back surface  12   b  is oriented toward the colored resin layer  13   a  side. 
     Moreover, in the present embodiment, the filler layer  13  for the resin layer is constituted of a laminate of the colored resin layer  13   a  and the transparent resin layer  13   b . However, in the present invention, the resin layers are not limited in particular other than having a colored resin layer positioned on the back surface side and a transparent resin layer positioned on the light receiving side and adjacent to the colored resin layer. The resin layers may have a resin layer other than the colored resin layer and the transparent resin layer. In addition, the colored resin layer and transparent resin layer may each be constituted of a plurality of resin layers. 
     (Transparent resin layer  13   b ) 
     The transparent resin layer  13   b  is disposed between the light receiving surface  12   a  of the solar cells  12  and the first protective member  10 . Here, the transparent resin layer  13   b  is a resin layer that transmits light in a wavelength range used in photoelectric conversion in the solar cells  12 . The transparent resin layer  13   b  preferably has average light transmittance of 85% or greater in a wavelength range of 400 nm-1100 nm. 
     The transparent resin layer  13   b  is at least one type of resin out of ethylene-vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), ethylene vinyl alcohol copolymer, acrylic resin, polyethylene (PE) and polypropylene (PP) or a resin composition containing at least one type of resin out of those resins. 
     From the standpoint of suitably protecting the solar cell strings  15 , the transparent resin layer  13   b  preferably is a cured resin having a crosslinked structure. 
     The solar cell module  1  is bonded with a silane coupling agent between the transparent resin layer  13   b  and the light receiving surfaces  12   a  of the solar cells  12 . 
     (Colored Resin Layer  13   a ) 
     The colored resin layer  13   a  is disposed between the back surface  12   b  and the second protective member  11 . The colored resin layer  13   a  is formed from a resin composition that includes a colorant. Specific examples of the colorant include, for example, white colorants such as titanium oxide particles and calcium carbonate particles, blue colorants such as ultramarine, black colorants such as carbon black, coloring agents that give the colored resin layer  13   a  a milky white color such as glass beads and light scattering materials, and the like. Among these, white titanium oxide particles are preferably used. Light becomes easily scattered in the colored resin layer  13   a  by including white titanium oxide particles in the colored resin layer  13   a , and the photoelectric conversion efficiency of the solar cell module  1  can be increased further. 
     The resin included in the colored resin layer  13   a  can be made to be, for example, at least one type of resin out of ethylene-vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), ethylene vinyl alcohol copolymer, acrylic resin, polyethylene (PE), and polypropylene (PP). The resin included in the colored resin layer  13   a  may be the same as the resin included the transparent resin layer  13   b  or may be different. 
     From the standpoint of suitably protecting the solar cell strings  15 , the colored resin layer  13   a  is preferably also a cured resin having a crosslinked structure identical to the colored resin layer  13   b.    
     (Manufacturing Method for Solar Cell Module  1 ) 
     Next, an example of the manufacturing method for the solar cell module  1  will be described with reference to  FIG. 2 . 
     First, a transparent resin sheet  22  for constituting the colored resin layer  13   a , a colored resin sheet  21  for constituting the colored resin layer  13   a , solar cell strings  15 , first protective member  10 , and second protective member  11  are prepared. The transparent resin sheet  22  and the colored resin sheet  21  are each formed from a resin composition that includes at least one type of resin out of ethylene-vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), ethylene vinyl alcohol copolymer, acrylic resin, polyethylene (PE), and polypropylene (PP), and a crosslinking agent. In addition, the colored resin sheet  21  preferably also includes a colorant as described above. 
     Specific examples of a preferably used crosslinking agent include, for example, organic peroxides. For example, organic peroxides that crosslink EVA include 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 3-di-t-hydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumyl peroxide, alpha,alpha&#39;-bis(t-butylperoxy isopropyl)hexane, n-butyl-4,4-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy) cyclohexane, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, t-butyl peroxybenzoate, benzoyl peroxide, and the like. 
     Next, the first protective member  10 , transparent resin sheet  22 , solar cell strings  15 , colored resin sheet  21 , and second protective member  11  are laminated in this order such that the light receiving surfaces  12   a  are oriented toward the transparent resin sheet  22  side and the back surface  12   b  is oriented toward the colored resin sheet  21  side, and a laminate  30  is fabricated. 
     Moreover, prior to the fabrication of this laminate  30 , a silane coupling agent is applied to at least one of a main surface  22   a  on the solar cell string  15  side of the transparent resin sheet  22  and light receiving surfaces  12   a  of each of the plurality of solar cells  12  constituting the solar cell strings  15 , and a silane coupling agent layer  23  is formed. The silane coupling agent may be applied to both the main surface  22   a  and the light receiving surfaces  12   a , may be applied only to the main surface  22   a , or may be applied to only the light receiving surfaces  12   a . In the following, an example in which the silane coupling agent layer  23  is formed by applying the silane coupling agent to the main surface  22   a  in the present embodiment will be described. 
     For the silane coupling agent, for example, aminosilane-based silane coupling agents or epoxysilane-based silane coupling agents can be used preferably, but the silane coupling agent is not limited to these. Specific examples of the aminosilane-based silane coupling agent, include, for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and the like. In addition, specific examples the epoxy-based silane coupling agent include, for example, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and the like. 
     When the silane coupling agent is applied, the application can be carried out using a liquid in which the silane coupling agent is dissolved or dispersed in an organic solvent such as isopropyl alcohol. 
     Next, the laminate  30  is thermocompression bonded using a laminating method. 
     Moreover, in the present embodiment, the silane coupling agent layer  23  is formed on the main surface  22   a  on the solar cell string  15  side of the transparent resin sheet  22 . Therefore, in this compression bonding process, the silane coupling agent layer  23  is made to adhere rigidly with the transparent resin sheet  22  and light receiving surfaces  12   a  by a reaction. 
     Next, a curing process is carried out. The curing process is a process in which a crosslinked structure is formed within the transparent resin sheet  22  and the colored resin sheet  21 . Specifically, the crosslinked structure is formed within the transparent resin sheet  22  and colored resin sheet  21  by heating the transparent resin sheet  22  and colored resin sheet  21  and reacting a crosslinking agent contained in the transparent resin sheet  22  and colored resin sheet  21 . Thus, the transparent resin sheet  22  and colored resin sheet  21  are cured and the transparent resin layer  13   b  and colored resin layer  13   a  are completed. 
     However, for example, when no silane coupling agent layer is formed, rigid adhesion to the transparent resin sheet and light receiving surface does not occur. Therefore, in the thermocompression bonding process, part of the colored resin sheet positioned on the back surface side may flow to the light receiving side, and may enter between the light receiving surface and transparent resin sheet. In such cases, part of the colored resin layer is positioned on the light receiving surface. Therefore, part of the light trying to be incident to the light receiving surface is shielded by the colored resin layer. Thus, the light receiving efficiency of the light receiving surface is reduced. Therefore, the output of the solar cell module is reduced. 
     Conversely, in the present embodiment, the silane coupling agent layer  23  is formed prior to the thermocompression bonding process. Therefore, the silane coupling agent layer  23  reacts immediately after the start of the compression bonding process, and bonding is formed between the light receiving surfaces  12   a  of the solar cells  12  and the transparent resin sheet  22  by the silane coupling agent. Thus, the transparent resin sheet  22  and light receiving surfaces  12   a  rigidly adhere. Thus, even if part of the colored resin sheet  21  positioned on the back surface  12   b  side flows to the light receiving surfaces  12   a  side, the colored resin sheet  21  cannot easily enter between the light receiving surfaces  12   a  and transparent resin sheet  22 . In other words, in the solar cell module  1 , the wrapping around of the colored resin layer  13   a  to the light receiving surfaces  12   a  of the solar cells  12  is suppressed by the bonding by the silane coupling agent. Therefore, in the manufacturing method of the present embodiment, positioning of part of the colored resin layer on the light receiving surfaces  12   a  is suppressed. As a result, reductions in the light receiving efficiency of the light receiving surfaces  12   a  can be suppressed. Therefore, the solar cell module  1  having an improved output can be manufactured. 
     EXAMPLE 
     In the present example, a solar cell module having an identical constitution to the solar cell module  1  according to the first embodiment above was manufactured according to the following outline. 
     First, a transparent EVA sheet with a thickness of 0.6 mm containing 2% by mass of 1,1-bis (t-butylperoxy)3,3,5-trimethylcyclohexane as a curing agent was disposed on a first protective member  10 , which was formed from a glass sheet. Next, an isopropyl alcohol solution containing N-2-(aminoethyl)-3-aminopropyltrimethoxysilane as the silane coupling agent was applied to the surface of the transparent EVA sheet and the silane coupling agent layer  23  was formed. Furthermore, solar cell strings  15 , a colored EVA sheet having a thickness of 0.6 mm, containing 2% by mass of 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane as a curing agent, and containing 5% by mass of titanium oxide as a colorant, and a second protective member  11  were laminated in this order on the transparent EVA sheet, and the laminate  30  was fabricated. Next, thermal compression bonding of the laminate  30  was carried out using a laminating method. Thereafter, the solar cell module was completed by introducing a crosslinked structure into the filler layer by holding for approximately one hour at approximately 150° C. 
     Next, the solar cell module was inspected as to whether the colored resin layer had wrapped around onto the light receiving surface by visual observation from the first protective member  10  side. As a result, none of the colored resin layer had wrapped around onto the light receiving surface in this example. 
     Furthermore, the output was measured when light with an intensity of 100 mW/cm 2  at AM 1.5 was made to shine on the solar cell module. The results are given in Table 1 which follows. 
     Comparative Example 
     A solar cell module was fabricated identically to the example above with the exception of the silane coupling agent not being applied, and inspection of whether or not the colored resin layer wrapped around to the light receiving surface and output measurements were carried out. In this comparative example, the colored resin layer was found to have wrapped around onto the light receiving surface. 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Output ratio (%) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Example 
                 100.3 
               
               
                   
                 Comparative Example 
                 100 
               
               
                   
                   
               
            
           
         
       
     
     Moreover, the output values in Table 1 above are standardized with the output value for the comparative example set at 100. 
     From the results of the example and comparative example, it can be seen that the wrapping and forming of the colored resin layer onto the light receiving surface can be suppressed by applying a silane coupling agent to the surface of the transparent resin sheet. In addition, it can be seen that a high output was obtained as shown in Table 1. 
     EXPLANATION OF THE ELEMENTS 
     
         
           1  Solar cell module 
           10  First protective member 
           11  Second protective member 
           12  Solar cell 
           12   a  Light receiving surface 
           12   b  Back surface 
           13  Filler layer 
           13   a  Colored resin layer 
           13   b  Transparent resin layer 
           14  Wiring material 
           15  Solar cell string 
           21  Colored resin sheet 
           22  Transparent resin sheet 
           23  Silane coupling agent layer 
           30  Laminate