Patent Publication Number: US-2019172962-A1

Title: Encapsulation structure and solar cell module

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefits of Taiwan application serial no. 106142492, filed on Dec. 5, 2017. The disclosure of which is hereby incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The disclosure relates to an encapsulation structure and a solar cell module. 
     BACKGROUND 
     The encapsulation material for the solar cell module generally adopts glass or ethylene tetrafluoroethylene (ETFE) as the protective layer and the water-barrier layer in present. 
     However, although glass has the function of water barrier, it is neither lightweight nor flexible and is readily fragmented. Moreover, the water-barrier effect of ETFE used as the protective layer is poor, and the surface hardness thereof is too poor to prevent the surface from being scratched. 
     Therefore, a simplified encapsulation structure with high light transmittance and low water permeability is in need for lightweight and flexible of the solar cell module. 
     SUMMARY 
     According to an embodiment of the disclosure, an encapsulation structure of a solar cell module is disposed on the light incident surface of the solar cell module. The encapsulation structure is consisted of a thermoplastic protective layer, a transparent water-barrier layer, and an adhesive layer. The thermoplastic protective layer is disposed on the outermost layer of the light incident surface, and the material thereof includes thermoplastic polyurethane (TPU), thermoplastic polyolefin (TPO), or thermoplastic elastomer (TPE). The transparent water-barrier layer is disposed between the adhesive layer and the thermoplastic protective layer. 
     According to another embodiment of the disclosure, an encapsulation structure of a solar cell module is disposed on the back light surface of the solar cell module. The encapsulation structure is consisted of a thermoplastic protective layer, a water-barrier layer, and an adhesive layer. The thermoplastic protective layer is disposed on the outermost layer of the back light surface, and the material thereof includes TPU, TPO, or TPE. The water-barrier layer is disposed between the adhesive layer and the thermoplastic protective layer. 
     According to yet another embodiment of the disclosure, a solar cell module includes a front plate encapsulation structure, a backplate encapsulation structure, and a plurality of solar cells encapsulated between the front plate encapsulation structure and the backplate encapsulation structure. The front plate encapsulation structure is consisted of a first thermoplastic protective layer, a first water-barrier layer, and a first adhesive layer, wherein the first water-barrier layer is disposed between the first thermoplastic protective layer and the first adhesive layer. The material of the first thermoplastic protective layer includes TPU, TPO, or TPE. The first water-barrier layer is a transparent water-barrier layer. The solar cells are directly in contact with the first adhesive layer. 
     Based on the above, in the disclosure, by including a specific protective layer with a single water-barrier layer and a single adhesive layer, the effects of high light transmittance and low water permeability for the front plate encapsulation structure may be achieved, and the effect of low water permeability for the backplate encapsulation structure may also be achieved. Moreover, the solar cell module of the disclosure has the front plate encapsulation structure or the backplate encapsulation structure, and therefore not only has the features of lightweight and flexibility, but the life and reliability of the solar cell module may also be increased at the same time. 
     Several exemplary embodiments accompanied with figures are described in detail below to further describe the disclosure in details. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments and, together with the description, serve to explain the principles of the disclosure. 
         FIG. 1A  is a schematic of the encapsulation structure of a solar cell module according to the first embodiment of the disclosure. 
         FIG. 1B  is a schematic of the encapsulation structure of a solar cell module according to the second embodiment of the disclosure. 
         FIG. 2  is a schematic of a solar cell module according to the third embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS 
     Embodiments are provided hereinafter and described in detail with reference to figures. However, the embodiments provided are not intended to limit the scope of the disclosure. Moreover, the figures are only descriptive and are not drawn to scale, and different layers or regions may be enlarged or shrunk to be shown in a single figure. Moreover, although different elements, regions, and/or film layers are described using, for instance, “first” and “second” in the specification, the elements, regions, and/or film layers should not be limited to these terms. Instead, these terms are only used to distinguish an element, region, or film layer from another element, region, or film layer. Therefore, a first element, region, or film layer discussed below may be referred to as a second element, region, or film layer without violating the teaching of the embodiments. Moreover, to facilitate understanding, the same elements in the following are described with the same reference numerals. 
       FIG. 1A  is a schematic of the encapsulation structure of a solar cell module according to the first embodiment of the disclosure. 
     Referring to  FIG. 1A , an encapsulation structure  100  of the disclosure is used in a solar cell module and is generally disposed on a light incident surface  100   a  of the solar cell module. The encapsulation structure  100  is consisted of a thermoplastic protective layer  102 , a transparent water-barrier layer  104 , and an adhesive layer  106 . The thermoplastic protective layer  102  is disposed on the outermost layer of the light incident surface  100   a.  In other words, there are no other structural layers present besides the thermoplastic protective layer  102 , and the thermoplastic protective layer  102  is directly exposed to the external environment. The material of the thermoplastic protective layer  102  includes a thermoplastic polyurethane (TPU), a thermoplastic polyolefin (TPO), or a thermoplastic elastomer (TPE). The transparent water-barrier layer  104  is disposed between the adhesive layer  106  and the thermoplastic protective layer  102 . In an embodiment, the transparent water-barrier layer  104  may include a light-permeable material such as ultra-thin glass or a polymer having TFE (thin film encapsulation), wherein the ultra-thin glass refers to a glass having a thickness of 400 microns or less, alternatively a thickness of 150 microns or less. If the transparent water-barrier layer  104  is the polymer having TFE, then the polymer having TFE may include, for instance, polycarbonate (PC), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), fluoropolymer, polyvinyl fluoride (PVF), ethylene tetrafluoroethylene (ETFE), or polyvinylidene difluoride (PVDF). The material of the adhesive layer  106  is not particularly limited, and may be a thermoplastic adhesive layer or a thermosetting adhesive layer. In an embodiment, the material of the adhesive layer  106  includes TPU, TPO, TPE, or ethylene vinyl acetate (EVA). If the same material is used for the adhesive layer  106  and the thermoplastic protective layer  102 , then the same process conditions may be applied during encapsulation to facilitate process control. 
       FIG. 1B  is a schematic of the encapsulation structure of a solar cell module according to the second embodiment of the disclosure, wherein the same reference numerals as those of the first embodiment are used to represent the same or similar components. 
     Referring to  FIG. 1B , an encapsulation structure  100  of the disclosure may also be disposed on a back light surface  100   b  of the solar cell module. The encapsulation structure  100  is consisted of a thermoplastic protective layer  102 , a water-barrier layer  108 , and an adhesive layer  106 . The thermoplastic protective layer  102  is disposed on the outermost layer of the back light surface  100   b.  In other words, there are no other structural layers present besides the thermoplastic protective layer  102 , and the thermoplastic protective layer  102  is directly exposed to the external environment. The material of the thermoplastic protective layer  102  includes a thermoplastic polyurethane (TPU), a thermoplastic polyolefin (TPO), or a thermoplastic elastomer (TPE). The water-barrier layer  108  is disposed between the adhesive layer  106  and the thermoplastic protective layer  102 . In an embodiment, the water-barrier layer  108  may be a metal foil, such as aluminum foil, copper foil, or stainless steel foil, but the disclosure is not limited thereto. In another embodiment, the water-barrier layer  108  is, for instance, a light-permeable material such as ultra-thin glass or a polymer having TFE, wherein ultra-thin glass refers to a glass having a thickness of 400 microns or less, alternatively 150 microns or less. If the water-barrier layer  108  is the polymer having TFE, then the polymer having TFE may be, for instance, PC, PEN, PET, fluoropolymer, PVF, ETFE, or PVDF. The material of the adhesive layer  106  is not particularly limited, and may be a thermoplastic adhesive layer or a thermosetting adhesive layer. In an embodiment, the material of the adhesive layer  106  includes TPU, TPO, TPE, or ethylene vinyl acetate (EVA). If the same material is used for the adhesive layer  106  and the thermoplastic protective layer  102 , then the same process conditions may be applied during encapsulation to facilitate process control. 
       FIG. 2  is a schematic of a solar cell module according to the third embodiment of the disclosure. 
     Referring to  FIG. 2 , a solar cell module  200  includes a front plate encapsulation structure  202 , a backplate encapsulation structure  204 , and a plurality of solar cells  206  encapsulated between the front plate encapsulation structure  202  and the backplate encapsulation structure  204 . The solar cells  206  are, for instance, CIGS solar cells, monocrystalline silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, CdTe solar cells, perovskite solar cells, or a combination of the solar cells, such as tandem solar cells. In an embodiment, the solar cells  206  form a solar cell group connected in parallel and series. The front plate encapsulation structure  202  is consisted of a first thermoplastic protective layer  208 , a first water-barrier layer  210 , and a first adhesive layer  212 , wherein the first water-barrier layer  210  is disposed between the first thermoplastic protective layer  208  and the first adhesive layer  212 . The material of the first thermoplastic protective layer  208  in the present embodiment includes TPU, TPO, or TPE, and in terns of preventing yellowing, TPU may adopt aliphatic TPU. In the present embodiment, the first thermoplastic protective layer  208  is disposed on the outermost layer of the solar cell module  200 , and therefore when the surface of the first thermoplastic protective layer  208  is damaged by, for instance, scratching, the scratch may be repaired by heating. 
     Referring further to  FIG. 2 , the first water-barrier layer  210  is a transparent water-barrier layer such that light may be incident on the internal solar cells  206  from outside of the front plate encapsulation structure  202 . The first water-barrier layer  210  may be ultra-thin glass or a polymer having TFE, wherein the ultra-thin glass refers to glass having a thickness of 400 microns or less (alternatively 150 microns or less). If the first water-barrier layer  210  is the polymer having TFE, then the polymer having TFE may include, for instance, PC, PEN, PET, fluoropolymer, PVF, ETFE, or PVDF. The first adhesive layer  212  is not limited to a thermoplastic adhesive layer or a thermosetting adhesive layer. For instance, the material of the first adhesive layer  212  is, for instance, TPU, TPO, TPE, or EVA. If the same material is used for the first adhesive layer  212  and the first thermoplastic protective layer  208 , then the same process conditions may be applied during encapsulation to facilitate process control. The solar cells  206  are directly in contact with the first adhesive layer  212  and connected in parallel and series by wires  214  (such as ribbon or copper wires). 
     In the present embodiment, the backplate encapsulation structure  204  may be consisted of a second thermoplastic protective layer  216 , a second water-barrier layer  218 , and a second adhesive layer  220 , wherein the second water-barrier layer  218  is disposed between the second thermoplastic protective layer  216  and the second adhesive layer  220 . The material of the second thermoplastic protective layer  216  may be, but not limited to, for instance, TPU, TPO, or TPE. The second water-barrier layer  218  is, for instance, a metal foil, a glass having a thickness of 400 microns or less (alternatively 150 microns or less) (i.e. ultra-thin glass), or a polymer having TFE. If the second water-barrier layer  218  is the polymer having TFE, then the polymer having TFE may be, for instance, PC, PEN, PET, fluoropolymer, PVF, ETFE, or PVDF. If the second water-barrier layer  218  is a metal foil, then the second water-barrier layer  218  may adopt, for instance, aluminum foil, copper foil, or stainless steel foil, but the disclosure is not limited thereto. When the first water-barrier layer  210  and the second water-barrier layer  218  in the front plate encapsulation structure  202  and the backplate encapsulation structure  204  are both flexible, the solar cell module  200  which is made from aforementioned materials may also be flexible. The second adhesive layer  220  may include but not limited to a thermoplastic adhesive layer or a thermosetting adhesive layer. In an embodiment, the material of the second adhesive layer  220  is, for instance, TPU, TPO, TPE, or EVA. In terms of bonding compatibility, the second adhesive layer  220  and the first adhesive layer  212  may adopt the same material. Therefore, the solar cells  206  are directly in contact with the second adhesive layer  220  and the first adhesive layer  212  after encapsulation, and the interface (dotted line) between the first adhesive layer  212  and the second adhesive layer  220  is not readily distinguished due to fusion. In an embodiment, the backplate encapsulation structure  204  may also be directly bonded to a glass front plate and an adhesive layer to form a solar cell module. 
     Moreover, the solar cell module  200  of the present embodiment may also include a pattern layer  222  disposed on an outer surface  204   a  of the backplate encapsulation structure  204  that is aesthetic or suitable for commercial (advertising) use while generating electricity by absorbing sunlight. The pattern layer  222  includes, for instance, an ink layer  224  and a white pigment layer  226  disposed between the ink layer  224  and the second thermoplastic protective layer  216 , wherein the white pigment layer  226  is, for instance, a white material such as titanium oxide used as a white underlayer to allow the color and pattern of the ink layer  224  to stand out. In terms of the formability of the pattern layer  222 , the material of the second thermoplastic protective layer  216  may adopt TPU. 
     To verify the effects above, experiments are provided below, but the disclosure is not limited to the experiments below. 
     EXPERIMENTAL EXAMPLE 1 
     TPU/transparent water-barrier layer/TPU structure was used as the encapsulation structure of the front plate, TPU/aluminum foil (about 20 microns)/TPU structure was used as the encapsulation structure of the backplate, and the materials of the encapsulation structures of the front plate and the backplate were cut into a size greater than that of the solar cell module (about slightly greater than 1 cm at the edge). After stacking above structures, the lamination was performed on the stack of the encapsulation materials at 120° C./15 min. The encapsulation for front plate and backplate of a module was complete after the encapsulation materials were cooled. 
     Next, a water permeability test was performed at a humidity of 85% in a 40° C. environment, wherein the transparent water-barrier layer was UBSF-510 made by 3M. The results are shown in Table 1 below. 
     COMPARATIVE EXAMPLE 2 
     The materials of the encapsulation structures of the front plate and the backplate were changed to ETFE/EVA, and the other conditions were the same as those of experimental example 1, and a water permeability test was performed at a humidity of 85% in a 40° C. environment after lamination. The results are shown in Table 1 below. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                 Front plate of 
               
               
                   
                   
                 Backplate of 
                 experimental 
               
               
                   
                   
                 experimental 
                 example 1 
               
               
                   
                 Comparative 
                 example 1 
                 (TPU/transparent 
               
               
                 Encapsulation 
                 example 1 
                 (TPU/aluminum 
                 water-barrier 
               
               
                 material 
                 (ETFE/EVA) 
                 foil/TPU) 
                 layer/TPU) 
               
               
                   
               
             
            
               
                 Water 
                 &gt;10 
                 1.57E−4 
                 4.62E−2 
               
               
                 permeability 
               
               
                 (g/m 2 -24 hr) 
               
               
                   
               
            
           
         
       
     
     It may be known from Table 1 that, the water permeability of ETFE/EVA is greater than 10, the water permeability of TPU/transparent water-barrier layer/TPU is 4.62E-2 g/m 2 -24 hrs, and the water permeability of TPU/aluminum foil/TPU is 1.57E-4 g/m 2 -24 hrs, indicating that the disclosure has good water-barrier capability and also simplify the encapsuation structure of the solar cell. 
     EXPERIMENTAL EXAMPLE 2 
     A titanium oxide underlayer was first printed on the surface of a TPU film, and then a pattern was printed on the titanium oxide underlayer using an inkjet printer to complete the manufacture of the pattern layer. Next, a cross-cut test (anti-tear test) was performed on the pattern layer on the TPU film, and the results indicate the pattern layer was barely torn off 
     COMPARATIVE EXAMPLE 2 
     The pattern layer was made using the same method as experimental example 2, but the TPU film as changed to an ETFE film. Next, a cross-cut test (anti-tear test) was performed on the pattern layer on the ETFE film, and the results indicate most of the pattern layer was torn off 
     Based on the above, in the disclosure, via a specific encapsulation structure, the solar cell encapsulation structure may be simplified to distinguish from current solar cell encapsulation structures to achieve the effects of high light transmittance and low water permeability and the features of lightweight and flexibility. At the same time, the life and reliability of the solar cell module may also be increased. Therefore, the module of the disclosure may be applied in portable and wearable mobile power-generating devices. 
     It will be apparent to those skilled in the art that various modifications and variations may be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.