JP2017069244A - Solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module excellent in power generation efficiency, productivity and low cost.SOLUTION: The solar cell module is configured to include a solar cell and so that a reflection sheet with a diffusion layer including inorganic particles is positioned at any other portion than a solar cell when being cut at a surface in parallel to a light-receiving surface of the solar cell module.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a solar cell module.

  In recent years, it is predicted that global warming will occur due to the greenhouse effect due to the increase in carbon dioxide, and the demand for clean energy that does not emit carbon dioxide is increasing. Under such circumstances, solar power generation using a solar cell module has received much attention because of its high safety and versatility. Generally, a solar cell module has a configuration in which a cover material, a front side sealing material, a solar cell that performs photoelectric conversion, a back side sealing material, and a back sheet are laminated in order from the light receiving surface side.

  In the conventional solar cell module, a technique for improving the power generation efficiency of the solar cell module is generally used by reflecting the light passing between the solar cells with a back sheet or a sealing material and incorporating the light into the cell. ing. And in order to improve the power generation efficiency of a solar cell module more, the technique (patent document 1) which uses the sheet | seat which has specific unevenness | corrugation as a back sheet, and specific unevenness | corrugation between a front side sealing material and a back side sealing material A technique (Patent Document 2) for inserting a sheet having a sheet is known.

JP 2011-159683 A Japanese translation of PCT publication No. 2002-513210

  However, the solar cell module using the sheet having the concavo-convex structure as in Patent Documents 1 and 2 increases the labor and cost for manufacturing by using the sheet having the concavo-convex structure, and heating in the manufacturing process. There is a concern that the power generation efficiency may decrease due to the deformation of the uneven structure of the sheet.

  The object of the present invention is to provide a solar cell module that improves the drawbacks of the prior art and is excellent in power generation efficiency, productivity, and low cost.

In order to solve the above problems, the solar cell module of the present invention has the following configuration.
(1) When a solar cell module is cut along a plane including solar cells and parallel to the light receiving surface of the solar cell module, a reflective sheet having a diffusion layer containing inorganic particles is located in a portion other than the solar cells. The solar cell module characterized by the above-mentioned.
(2) The solar cell module according to (1), wherein the reflective sheet is located between a front side sealing material and a back side sealing material.
(3) The solar cell module according to (1) or (2), wherein the diffusion layer contains 10% by mass to 80% by mass of inorganic particles in 100% by mass of all components of the diffusion layer.
(4) The solar cell module according to any one of (1) to (3), wherein the reflective sheet has a reflective layer containing a polyester resin.
(5) The solar cell module according to (4), wherein the reflective layer includes a cavity.
(6) The solar cell module according to (4) or (5), wherein the reflective layer contains 10 to 50 parts by mass of an incompatible polymer with respect to 100 parts by mass of the polyester resin.
(7) The solar cell module according to any one of (4) to (6), wherein the front side sealing material, the diffusion layer, the reflective layer, and the back side sealing material are positioned in this order.

  According to the present invention, a solar cell module excellent in power generation efficiency, productivity, and low cost can be obtained.

It is a perspective view of the solar cell module which concerns on one embodiment of this invention. It is sectional drawing at the time of cut | disconnecting the solar cell module which concerns on one embodiment of this invention in a surface perpendicular | vertical to the light-receiving surface of a solar cell module including a photovoltaic cell. Sectional drawing when the reflective sheet used for the solar cell module which concerns on one embodiment of this invention is cut | disconnected in a surface perpendicular | vertical to a sheet | seat surface is shown. The specific example of the reflective sheet between a photovoltaic cell and a photovoltaic cell is shown. It is II sectional drawing of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  When the solar cell module of the present invention is cut along a plane parallel to the light receiving surface of the solar cell module including the solar cell module, the reflective sheet having a diffusion layer containing inorganic particles is other than the solar cell. It is located in this part.

  FIG. 1 is a perspective view of a solar cell module according to an embodiment of the present invention. FIG. 2 shows a cross-sectional view of a solar cell module according to an embodiment of the present invention cut along a plane that includes solar cells and is perpendicular to the light receiving surface of the solar cell module. FIG. 3 is a cross-sectional view of the reflective sheet used in the solar cell module according to one embodiment of the present invention, cut along a plane perpendicular to the sheet surface.

  As shown in FIG.1 and FIG.2, the solar cell module 1 which concerns on one embodiment of this invention is the cover agent 7, the front side sealing material 6, the photovoltaic cell 8, the reflective sheet 2, and the back side in order from the light-receiving surface side. The sealing material 5 and the back sheet 9 have a laminated structure. The reflection sheet 2 has a diffusion layer 3 and a reflection layer 4, 3 in FIG. 2 indicates a diffusion layer, and 4 indicates a reflection layer.

  From the viewpoint of improving power generation efficiency, the solar cell module of the present invention includes a diffusion layer containing inorganic particles when the solar cell module is cut along a plane that includes solar cells and is parallel to the light receiving surface of the solar cell module. It is important that the reflective sheet to be located in a portion other than the solar battery cell.

  The surface including the solar battery cell and parallel to the light receiving surface of the solar battery module may be any surface as long as the solar cell is included and is parallel to the light receiving surface of the solar battery module. That is, it can be arbitrarily determined within the range of the vertical length of the solar battery cell (12 or less in FIG. 2, sometimes referred to as the height of the solar battery cell).

  Here, “when the solar cell is included and when cut by a plane parallel to the light receiving surface of the solar cell module, the reflective sheet is located at a portion other than the solar cell” includes the solar cell and the solar cell. In a cross section obtained by cutting at any one of the planes parallel to the light receiving surface of the module, it means that the reflection sheet exists in all or part of the portion other than the solar battery cell. That is, when only a mode (a and c in FIG. 4) in which the reflective sheet is located in a portion other than the solar battery cells when cut on all the surfaces including the solar battery cells and parallel to the light receiving surface of the solar battery module. However, depending on how to define the plane including the solar battery cell and parallel to the light receiving surface of the solar battery module, the reflective sheet may or may not be located in a part other than the solar battery cell (b in FIG. 4). d and f), a mode in which the solar cell surface and the reflection sheet surface are not parallel (e in FIG. 4) is also included.

  In the solar cell module of the present invention, if attention is paid to improving the power generation efficiency of the solar cell module, in the cross section obtained when the solar cell module is cut by a plane parallel to the light receiving surface of the solar cell module, including the solar cells. The larger the range in which the reflective sheet is located, the better, and the aspect in which the reflective sheet is located in all parts other than the solar cells (a in FIG. 5) is most preferred. By enlarging the range in which the reflection sheet is located, it is possible to efficiently reflect light that has passed through the gap between the solar cells, and as a result, the power generation efficiency of the solar cell module is improved.

  Focusing on reducing the manufacturing cost of the solar cell module and simplifying the manufacturing process, in the cross section obtained when the solar cell module is cut along a plane parallel to the light receiving surface of the solar cell module, the solar cell An embodiment (b or c in FIG. 5) in which the reflective sheet is positioned so as to linearly fill the gaps between the battery cells is preferable. In order to obtain the embodiment shown in FIG. 5b or c, a strip-shaped reflection sheet is sufficient, and therefore, it is not necessary to cut out a cell portion from the reflection sheet. Therefore, by adopting the mode of FIG. 5b or c, the manufacturing cost can be reduced and the manufacturing process can be simplified.

  In the solar cell module of this invention, it is preferable that a reflection sheet is located between a front side sealing material and a back side sealing material from a viewpoint of improving the electric power generation efficiency of a solar cell module. By setting it as such an aspect, it becomes possible to reflect efficiently the light which passed through the gap | interval of the photovoltaic cell, and, as a result, the electric power generation efficiency of a photovoltaic module improves.

  In the solar cell module of the present invention, from the viewpoint of the productivity and power generation efficiency of the solar cell module, the thickness of the reflection sheet is preferably in the range of 25 μm to 300 μm, and more preferably in the range of 50 μm to 200 μm. . By setting the thickness of the reflection sheet to 25 μm or more, wrinkles can be prevented from occurring in the reflection sheet in the solar cell module manufacturing process. In addition, by setting the thickness of the reflection sheet to 300 μm or less, it becomes possible to prevent the cells from being covered with the shadow of the reflection sheet in the time zone (morning or evening) where the solar altitude is low, and the power generation efficiency is improved.

  In addition, since the reflection sheet has a diffusion layer containing inorganic particles, the reflection angle formed from the interface between the light reflected by the diffusion layer and the cover material or the sealing material is increased, so that the reflected light entering the cell Can be increased. As a result, the power generation efficiency of the solar cell module is improved.

  Examples of inorganic particles contained in the diffusion layer include calcium carbonate, magnesium carbonate, zinc carbonate, titanium oxide, zinc oxide, cerium oxide, magnesium oxide, barium sulfate, zinc sulfide, calcium phosphate, alumina, mica, titanium mica, talc, Examples include clay, kaolin, lithium fluoride, and calcium fluoride. Among these, it is preferable to use titanium oxide from the viewpoints of weather resistance and diffusibility.

  Titanium oxide used for the diffusion layer is, for example, anatase-type titanium oxide or rutile-type titanium oxide, but was measured by the minimum declination method from the viewpoint of increasing the difference in refractive index from the polyester used for the diffusion layer. Those having a refractive index of 2.7 or more are preferred, and rutile type titanium oxide is particularly preferred.

  The titanium oxide used for the diffusion layer is preferably a titanium oxide having a high purity with a small content of coloring elements such as vanadium, iron, niobium, copper and manganese, from the viewpoint of reducing the light absorption capability for visible light, In particular, the vanadium content in the titanium oxide is preferably 5 ppm or less by mass (hereinafter sometimes referred to as high-purity titanium oxide).

  Examples of the high-purity titanium oxide include titanium oxide produced by a chlorine method process. In the chlorine process, first, rutile ore mainly composed of titanium oxide is reacted with chlorine gas in a high-temperature furnace at about 1,000 ° C. to produce titanium tetrachloride. Subsequently, high purity titanium oxide can be obtained by burning this titanium tetrachloride with oxygen.

  The high-purity titanium oxide is preferably one whose surface is coated with at least one inert inorganic oxide selected from the group consisting of silica, alumina and zirconia. By setting it as such an aspect, not only the light resistance of a film improves, but the photocatalytic activity of a titanium oxide is suppressed and the high light reflectivity of a titanium oxide is maintained. Furthermore, high-purity titanium oxide coated with two or three kinds of inert inorganic oxides is more preferably used, and in particular, a plurality of inert inorganic oxides essential for silica are used in combination. The high-purity titanium oxide used is particularly preferably used.

  Furthermore, in order to improve the dispersibility of the inorganic particles in the resin, the inorganic particles are subjected to surface treatment with a silicon compound, a polyhydric alcohol compound, an amine compound, a fatty acid, a fatty acid ester, or the like on the surface of the inorganic particle. Can be used.

  As the surface treatment agent, for example, at least one kind of inorganic compound selected from a siloxane compound and a silane coupling agent can be used, and these can also be used in combination. Furthermore, at least one organic compound selected from the group consisting of a siloxane compound, a silane coupling agent, a polyol, and polyethylene glycol can be used. These inorganic compounds and organic compounds can also be used in combination.

  From the viewpoint of obtaining a reflective sheet having a homogeneous diffusion layer, the inorganic particles used in the present invention preferably have a lower limit of the number average secondary particle size of 0.05 μm, more preferably 0.1 μm. preferable. By making the number average secondary particle size of the inorganic particles 0.05 μm or more, it is possible to suppress a decrease in the dispersibility of the inorganic particles in the diffusion layer, and thus to obtain a reflective sheet having a homogeneous diffusion layer Can do.

  Further, the upper limit value of the number average secondary particle size of the inorganic particles is preferably 7 μm, and more preferably 3 μm. By setting the number average secondary particle size of the inorganic particles to 7 μm or less, it is possible to prevent the voids formed in the diffusion layer from becoming rough, and a reflective sheet having a high reflectance can be obtained.

  In the solar cell module of the present invention, the diffusion layer may contain 10% by mass or more and 80% by mass or less of inorganic particles in 100% by mass of the total components of the diffusion layer, from the viewpoint of achieving both mechanical properties and diffusibility of the reflective sheet. Preferably, it is more preferably 10% by mass or more and 50% by mass or less. By increasing the amount of inorganic particles, it becomes possible to increase the diffusibility, and by reducing the amount of inorganic particles, it is possible to suppress a decrease in mechanical properties of the reflective sheet.

  In the solar cell module of the present invention, the thickness of the diffusion layer is not particularly limited as long as the effects of the present invention are not impaired, but the lower limit value of the thickness of the diffusion layer is preferably 2 μm, more preferably 10 μm. preferable. By setting the thickness of the diffusion layer to 2 μm or more, the diffusion layer has a function of diffusing light. Moreover, the electric power generation efficiency of a solar cell module can be improved by the thickness of a diffusion layer being 10 micrometers or more. Further, the upper limit value of the thickness of the diffusion layer is preferably 188 μm because there is no effect even if the thickness is greater than a certain thickness from the viewpoint of productivity and diffusion performance.

  In the solar cell module of this invention, it is preferable that a reflection sheet has a reflection layer containing a polyester resin from a viewpoint of productivity, mechanical characteristics, and durability.

  Here, the polyester resin is a general term for polymer compounds having an ester bond in the repeating unit of the main chain. The polyester resin is usually a dicarboxylic acid, a hydroxycarboxylic acid, or a derivative thereof (hereinafter sometimes collectively referred to as a dicarboxylic acid or a dicarboxylic acid component) and a diol or a derivative thereof (hereinafter referred to as a diol or the like). It may be obtained by subjecting a diol component or the like) to a polycondensation reaction. In the solar cell module of the present invention, the polyester resin may be one type or plural types.

  Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, adipic acid, and sebacic acid. Examples of the diol include ethylene glycol, trimethylene glycol, tetramethylene glycol, and cyclohexanedimethanol. Examples of the polyester resin include polyethylene terephthalate, polyethylene naphthalate, polymethylene terephthalate, polytetramethylene terephthalate, polyethylene-p-oxybenzoate, poly-1,4-cyclohexylenedimethylene terephthalate, and polyethylene-2,6- And naphthalene dicarboxylate.

  The polyester resin in the solar cell module of the present invention is preferably polyethylene terephthalate or polyethylene naphthalate from the viewpoint of productivity, mechanical properties, and durability, and polyethylene from the viewpoint of water resistance, durability, and chemical resistance. More preferably, it is terephthalate.

  The polyester resin in the solar cell module of the present invention may be a homopolyester resin or a copolyester resin. Examples of the copolymer component include diol components such as diethylene glycol, neopentyl glycol, and polyalkylene glycol. And dicarboxylic acid components such as adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 5-sodium sulfoisophthalic acid.

  Moreover, in the solar cell module of this invention, unless the effect of this invention is impaired, various additives can also be added in a polyester resin. Examples of the additive include an antioxidant and an antistatic agent.

  In the solar cell module of the present invention, the reflective layer preferably includes a cavity. When the reflection layer has a cavity, a difference in refractive index occurs between the polyester resin portion and the cavity portion in the reflection layer, and the light incident on the reflection sheet can be efficiently reflected by the difference in refractive index.

  The cavity in the reflective layer may be a continuous cavity or a discontinuous cavity as long as the effects of the present invention are not impaired, but is preferably a discontinuous cavity from the viewpoint of the mechanical strength of the reflective sheet. In addition, the ratio of the area of the cavity portion in the entire reflection layer (hereinafter sometimes referred to as porosity) in the cross section obtained by cutting the reflection sheet along a plane perpendicular to the sheet surface is the mechanical strength of the reflection sheet. And 10% to 50% from the viewpoint of achieving both improved reflectance. The upper limit value of the porosity in the reflective layer is more preferably 40% from the viewpoint of suppressing a decrease in mechanical strength. On the other hand, the lower limit value of the porosity in the reflective layer is more preferably 20% from the viewpoint of improving the reflectance.

  The porosity here means that an image obtained by imaging a cross-section obtained by cutting a reflective sheet with a plane perpendicular to the sheet surface with a scanning electron microscope at a magnification of 3,000 times is automatically used. It means the porosity obtained by binarization processing and calculating the ratio of the number of pixels in the cavity portion to the sum of the number of pixels in the cavity portion and the resin portion.

  In the solar cell module of the present invention, from the viewpoint of obtaining a high reflectance, the thickness of the reflective layer is preferably 50 μm or more, more preferably 75 μm or more, and further preferably 125 μm or more. The upper limit of the thickness of the reflective layer is not particularly limited as long as the effects of the present invention are not impaired, but even if it is 300 μm or more, there is no effect in improving the reflection performance.

  In the solar cell module of the present invention, the reflective layer preferably contains an incompatible polymer. When the reflective layer contains an incompatible polymer, the incompatible polymer is finely dispersed in the polyester resin, and a cavity is formed around the incompatible polymer by stretching (for example, biaxial stretching). Since the refractive index is different between the cavity and the polyester resin, the reflective layer is whitened and the reflectance is improved. That is, as the content of the incompatible polymer is increased, the number of cavity nuclei is increased and the number of cavity layers is increased, so that the reflectance is improved and high luminance is contributed.

  In the solar cell module of the present invention, from the viewpoint of improving productivity and reflectance while maintaining the mechanical strength of the reflective sheet, the reflective layer contains 10 mass of incompatible polymer with respect to 100 mass parts of the polyester resin. It is preferable to contain at least 50 parts by weight. From the viewpoint of the mechanical strength of the film, the upper limit of the amount of the incompatible polymer in the reflective layer is more preferably 30 parts by mass and even more preferably 25 parts by mass with respect to 100 parts by mass of the polyester resin. The lower limit of the amount of the incompatible polymer in the reflective layer is sufficient if it is about 10 parts by mass with respect to 100 parts by mass of the polyester resin from the viewpoint of improving the reflectance.

  Examples of the incompatible polymer used in the solar cell module of the present invention include poly-3-methylphthalene-1, poly-4-methylpentene-1, polyvinyl t-butane, and 1,4-trans-poly-2. , 3-dimethylbutadiene, polyvinylcyclohexane, polystyrene, polymethylstyrene, polydimethylstyrene, polyfluorostyrene, poly-2-methyl-4-fluorostyrene, polyvinyl tert-butyl ether, cellulose triacetate, cellulose tripropionate, Examples thereof include polymers having a melting point of 180 ° C. or higher selected from polyvinyl fluoride, amorphous polyolefin, cyclic olefin copolymer resin, polychlorotrifluoroethylene, and the like.

  Among these, poly-4-methylpentene-1 and cyclic olefin copolymer resin are particularly preferably used as the incompatible polymer for the polyester resin base material. The cyclic olefin copolymer resin is a resin obtained by copolymerizing ethylene with bicycloalkene and / or tricycloalkene.

  In order to disperse the incompatible polymer more uniformly, it is effective to use a dispersion aid. The dispersion aid here is a general term for compounds having an effect of promoting dispersion of an incompatible polymer.

  In the solar cell module of the present invention, the dispersion aid is preferably a thermoplastic polyester elastomer or polyalkylene glycol, more preferably polyalkylene glycol, and still more preferably polyethylene glycol. Further, in order to improve the dispersibility of the incompatible polymer, a copolymer of polybutylene terephthalate and polytetramethylene glycol may be used.

  The content of the dispersion aid is preferably 3% by mass or more and 40% by mass or less based on 100% by mass of the entire reflective layer from the viewpoint of achieving both improvement of the reflectance of the reflection sheet and maintenance of mechanical properties. By increasing the content of the dispersion aid within the above range, the dispersibility of the incompatible polymer is improved, and as a result, the reflectance of the reflective sheet is improved. On the other hand, by reducing the content of the dispersion aid, the mechanical properties of the reflective sheet can be maintained without impairing the original properties of the film base material. The dispersion aid can be mixed with a film base polymer in advance and adjusted as a master polymer (master chip).

  The diffusion layer and the reflection layer preferably contain a light stabilizer from the viewpoint of improving weather resistance. The content of the light stabilizer is from 0.1 to 5% by mass, with 100% by mass of all components of the diffusion layer or the reflective layer, from the viewpoint of improving weather resistance and minimizing coloring by the light stabilizer. Preferably, it is 0.5-5 mass%, More preferably, it is 1-5 mass%. Generally, weather resistance is improved by increasing the content of the light stabilizer, and coloring by the light stabilizer is reduced by reducing the content.

  The light stabilizer can be used alone or in combination of two or more. In the case of using a mixture of a plurality of types, the content of the light stabilizer refers to the total content of all the light stabilizers used, not the content of each light stabilizer.

  When the light stabilizer is used in the solar cell module of the present invention, it has excellent heat resistance, good compatibility with the above-described polyester resin, can be uniformly dispersed, and has less coloring, and the reflection characteristics of the polyester resin and the reflective layer It is desirable to select one that does not adversely affect As the light stabilizer, for example, various light stabilizers such as salicylic acid-based, benzophenone-based, benzotriazole-based, cyanoacrylate-based, and triazine-based UV absorbers, and hindered amine-based UV stabilizers are applicable. . More specific application examples are as follows.

(UV absorber)
Examples of the salicylic acid-based ultraviolet absorber include pt-butylphenyl salicylate and p-octylphenyl salicylate.

  Examples of the benzophenone-based ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, and 2,2′-4,4′-tetrahydroxybenzophenone. 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenyl) methane, and the like.

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-butylphenyl) benzotriazole, and 2- (2′-hydroxy). -3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'methylphenyl) -5-chlorobenzotriazole, 2- (2'- Hydroxy-3 ′, 5′-di-t-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzene Zotriazole, 2,2′methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2 (2′hydroxy-5′-meta Acryloxyphenyl) -2H-benzotriazole, 2- [2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′methylphenyl] benzotriazole and the like It is done.

  Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3'-diphenylacrylate.

  Examples of triazine ultraviolet absorbers include 2- (2,4-dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1,3,5-triazine, and 2,4-bis [2 -Hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3,5-triazine and the like.

  Other UV absorbers that can be used in the solar cell module of the present invention include 2-ethoxy-2′-ethyl oxazac acid bisanilide, and 2- (4,6-diphenyl-1,3,5-triazine. -2-yl) -5-[(hexyl) oxy] -phenol and 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hydroxy And phenyl.

(UV stabilizer)
Examples of hindered amine UV stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) separate and dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6 succinate. , 6-tetramethylpiperidine polycondensate and the like.

  Other ultraviolet stabilizers that can be used in the solar cell module of the present invention include nickel bis (octylphenyl) sulfide, [2-thiobis (4-t-octylphenolate)]-n-butylamine nickel, nickel complex- 3,5-di-tert-butyl-4-hydroxybenzyl-phosphate monoethylate, nickel-dibutyldithiocarbamate, 2,4-di-tert-butylphenyl-3 ′, 5′-di-tert-butyl-4 ′ -Hydroxybenzoate, and 2,4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4'-hydroxybenzoate.

  Among these light stabilizers, 2,2′-4,4′-tetrahydroxybenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenyl) methane, from the viewpoint of compatibility with the polyester resin, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], and 2- (4,6-diphenyl-1, 3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol is preferably used, and 2- (4,6-diphenyl-1,3,5- More preferably, triazin-2-yl) -5-[(hexyl) oxy] -phenol is used.

  In the solar cell module of the present invention, the diffusion layer and the reflective layer may be laminated via an adhesive layer or the like, or may be laminated directly without other layers, from the viewpoint of productivity, It is preferable that the layers are directly laminated without interposing other layers.

  In the solar cell module of the present invention, the front side sealing material, the diffusion layer, the reflective layer, and the back side sealing material are preferably located in this order. When the diffusion layer is located on the front side sealing material side, the light reflected on the cover material side inside the reflection sheet can be efficiently diffused by the diffusion layer, and the power generation efficiency of the module is improved.

  In the solar cell module of the present invention, the cover material is a material that is directly irradiated with sunlight, and is located on the outermost surface when viewed from the light receiving surface side. The cover material has sunlight permeability, electrical insulation, mechanical strength against snow and wind pressure, weather resistance against acid rain, ultraviolet rays, temperature, humidity, etc., impact resistance against dust, and withstands the manufacturing process. A certain level of scratch resistance is required.

  The material of the cover material is not particularly limited as long as the effect of the present invention is not impaired, and for example, glass, a resin molded product, or the like can be used. Examples of the resin molded product include polyolefin, poly (meth) acryl, polycarbonate, polyester, and fluororesin. Among these materials, it is preferable to use glass or polycarbonate from the viewpoint of strength and weather resistance.

  The thickness of the cover material is not particularly limited as long as the effect of the present invention is not impaired, but is preferably in the range of 50 μm or more and 10 cm or less. When the thickness of the cover material is 50 μm or more, the mechanical strength necessary for the solar cell module can be ensured. Moreover, since the thickness of a cover material is 10 cm or less, the weight increase of a solar cell module can be suppressed and the load at the time of installing a solar cell module is reduced.

  In the solar cell module of the present invention, examples of the front side sealing material and the back side sealing material include ionomer resin, EVA (ethylene-vinyl acetate copolymer resin), polyvinyl butyral, silicon resin, polyurethane, polyolefin, and modified polyolefin. Can be used. Among these, EVA can be preferably used from the viewpoints of weather resistance, adhesion to other members, and member costs.

  The thickness of the front side sealing material is not particularly limited as long as the effect of the present invention is not impaired, but is preferably in the range of 200 μm to 1 cm. When the thickness of the front side sealing material is 200 μm or more, it is possible to avoid the solar battery cell from being cracked due to the loading of various members in the manufacturing process of the solar battery module or the pressure due to heating (laminating). Moreover, when the thickness of the front side sealing material is 1 cm or less, an increase in the weight of the solar cell module can be suppressed, and a load when installing the solar cell module is reduced. In addition, the thickness of the back side sealing material is not particularly limited as long as the effects of the present invention are not impaired, but from the same viewpoint as the thickness of the front side sealing material, it is preferably in the range of 200 μm or more and 1 cm or less.

  In the solar battery module of the present invention, a solar battery cell is a photovoltaic element that converts light energy of sunlight into electric energy. The solar cells are connected in series or in parallel with an interval between the front side sealing material and the back side sealing material (FIG. 2).

  Examples of solar cells include single crystal silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, compound solar cells, and organic thin film solar cells. In the solar cell module of the invention, any type of solar cell may be used as long as the effects of the present invention are not impaired.

  The thickness from the cover material surface of the solar cell module of the present invention to the back sheet back surface (hereinafter sometimes referred to as the thickness of the solar cell module) is not particularly limited as long as the effect of the present invention is not impaired, but is 475 μm or more and 12.5 cm. The following range is preferable. When the thickness of the solar cell module is 475 μm or more, sufficient mechanical strength for use as a solar cell module can be ensured. Moreover, since the thickness of a solar cell module is 12.5 cm or less, the weight increase of a solar cell module can be suppressed and the load at the time of installing a solar cell module is reduced.

  In the production of the solar cell module of the present invention, a known method for producing a solar cell module can be used. For example, it is possible to use a method in which the above materials are laminated and heat-pressed. Specifically, the front side sealing material or the back side sealing material in a state of atmospheric pressure, a method of thermocompression bonding by pressing in a temperature environment higher than the melting point of the higher melting point, or the front side sealing material in a vacuum state Or the method of thermocompression-bonding by pressurizing in the temperature environment more than the melting | fusing point of the higher one among back side sealing materials is mentioned. From the viewpoint of suppressing the generation of bubbles in the solar cell module, it is preferable to pressurize in a vacuum state and perform thermocompression bonding. The melting point here is a melting point measured by a DSC method based on JIS K7121: 1987.

  EXAMPLES Hereinafter, although this invention is demonstrated along an Example, this invention is not restrict | limited by these Examples. Various characteristics were measured by the following methods.

<Evaluation method of characteristics>
(1) Reflective sheet thickness and thickness of each layer:
The thickness of the reflection sheet was measured according to JIS C2151: 2006. Specifically, the reflective sheet was cut by a plane perpendicular to the sheet surface using a microtome to obtain a slice sample. Using a field emission scanning electron microscope (FE-SEM) S-800 manufactured by Hitachi, Ltd., the section sample was imaged at three points at a magnification of 500 times, and the average value of the layer thickness was obtained from the three point images. The thickness of each layer was calculated. The total thickness of each layer was taken as the thickness of the reflective sheet.

(2) Confirmation of presence / absence of cavity in reflecting layer, cavity continuity, and porosity of reflecting layer:
The presence or absence of cavities in the reflective layer and the continuity of the cavities were determined by cutting the reflective sheet by the method described in (1), and observing the cross section of the obtained sample using a field emission scanning electron microscope (FE-SEM) S- Evaluation was performed based on the following criteria from an image obtained by imaging one point at a magnification of 3,000 times using 800. The presence or absence of cavities in the reflective layer and cavity continuity ◯ are the most preferable, and ◯ and △ are acceptable.
・ Cavity, discontinuity: ○
-There is a cavity, continuous: △
・ There is no cavity: ×
In addition, each of the three images obtained by imaging at a magnification of 3,000 using Hitachi field emission scanning electron microscope (FE-SEM) S-800 was automatically binarized, The ratio of the number of pixels of the cavity portion to the sum of the number of pixels of the cavity portion and the resin portion in the imaging was calculated, and the average value was defined as the porosity.

(3) Average relative reflectance of the reflective sheet:
Using a spectrophotometer (UV-3150 UV-VIS-NIR Spectrophotometer) manufactured by Shimadzu Corporation as a sample by cutting out the reflective sheet at 5 cm (longitudinal direction) × 5 cm (width direction), a basic using an attached integrating sphere In the configuration, the average relative reflectance at 400 nm to 1200 nm (hereinafter, simply referred to as “average relative reflectance”) was measured with reference to the sub-white plate of barium sulfate attached to the apparatus. The measurement conditions were a slit of 12 nm, a sampling pitch of 1 nm, and a high scanning speed. The measurement was performed three times, and the average value was calculated as the average relative reflectance.

(4) Power generation improvement rate by modularization:
The flux “HOZAN H722” was applied to the front and back silver electrode portions of the polycrystalline silicon solar cell “Gintech G156M3” with a dispenser, and the length of 155 mm was applied to the front and back silver electrodes. The wiring material “Hitachi Cable Co., Ltd. copper foil SSA-SPS0.2 × 1.5 (20)” cut into 10 mm from the one end of the cell on the front side is the end of the wiring material, and the back side is the front side. It was placed symmetrically, a soldering iron was brought into contact from the back side of the cell, and the front and back sides were simultaneously soldered to produce one cell string.

  Next, the direction of the length of the wiring material protruding from the cell of the produced 1 cell string and the extraction electrode “Cu foil A-SPS 0.23 × 6.0 manufactured by Hitachi Cable, Ltd.” cut into 180 mm were used. The long length direction was placed vertically, the flux was applied to the portion where the wiring material and the extraction electrode overlapped, and solder welding was performed to produce strings with the extraction electrode. At this time, the short-circuit current was measured according to the standard state of JIS C8914: 2005, and the power generation performance of the cell alone was obtained.

  Next, 190 mm × 190 mm glass (3.2 mm thick white plate heat-treated glass for solar cells manufactured by Asahi Glass Co., Ltd.) as a cover material, and 190 mm × 190 mm ethylene vinyl acetate (Sanvik sealing material 0.5 mm as a front side sealing material) (Thickness), a string with a take-out electrode for which the power generation performance evaluation of the single cell was carried out, and cut to 190 mm × 190 mm, and the center of the cut square was 156 mm (longitudinal) so that the cell could be included 17 mm inside from each side Direction) x 156 mm (width direction) cut out or 190 mm (longitudinal direction) x 17 mm (width direction) reflective sheet, and 190 mm x 190 mm ethylene vinyl acetate (Sanvik sealing) Material 0.5mm) and as a back sheet, 190mm x 190mm The laminated white polyester film “Lumirror” (registered trademark) MX11 manufactured by Toray Co., Ltd., having a thickness of 0.05 mm, is set in contact with the hot plate of the vacuum laminator, and the hot plate temperature is 145 ° C. Vacuum lamination was performed under the conditions of 1 minute, 1 minute of pressing, and 10 minutes of holding time to obtain a solar cell module. At this time, the strings with extraction electrodes were set so that the glass surface was on the cell surface side, and the reflective sheet was set so that the diffusion layer was on the front side sealing material side. The obtained solar cell module was subjected to measurement of a short-circuit current measured according to the standard state of JIS C8914: 2005, and set as the power generation performance after modularization.

From the power generation performance of the single cell thus obtained and the power generation performance after modularization, the performance improvement rate by modularization was calculated according to the following formula.
Power generation improvement rate by modularization (%) = (power generation performance after modularization / cell power generation performance-1) x 100 (%)
(5) Tape peeling:
Nichiban's “Cello Tape” (registered trademark) LP-15 was bonded to the diffusion layer side of the back sheet, the tape was peeled off according to JIS Z0237: 2009, and the state of the sample adhesion surface of the peeled tape was confirmed. The presence or absence of inorganic particles was visually confirmed. From the obtained results, the following criteria were evaluated. It is preferable that the inorganic particles do not adhere, and “◯” is regarded as acceptable.
No adhesion of inorganic particles: ○
Inorganic particles attached: ×
[Example 1]
A polyethylene terephthalate master chip in which 70 parts by mass of a polyethylene terephthalate chip and 50% by mass of titanium oxide having a number average secondary particle size of 0.25 μm are dispersed (containing 50% by mass of titanium oxide with respect to 100% by mass of the master chip) is contained. 30 parts by mass was vacuum-dried at a temperature of 180 ° C. for 3 hours, and then supplied to the extruder A heated to 280 ° C. as a diffusion layer material. Further, 100 parts by mass of a polyethylene terephthalate chip was vacuum-dried at a temperature of 180 ° C. for 3 hours, and then supplied to an extruder B heated to 280 ° C. as a reflective layer material. Next, these polymers were laminated through a laminating apparatus so that the thickness ratio of the film layer was 12 (diffuse layer): 63 (reflective layer), and formed into a sheet form from a T die. Furthermore, this sheet-like material is cooled and solidified with a cooling drum having a surface temperature of 25 ° C. to form an unstretched film, led to a roll group heated to 85 to 98 ° C., and stretched 3.4 times in the longitudinal direction. It cooled with the roll group of 21 degreeC. Subsequently, the both ends of the uniaxially stretched film thus obtained were guided to a tenter while being held with clips, and stretched 3.6 times in the width direction in an atmosphere heated to 120 ° C. Thereafter, heat setting was performed at 200 ° C. in the tenter, and after uniform cooling, the film was cooled to 25 ° C. and wound to obtain a reflective sheet having a thickness of 75 μm. The obtained reflection sheet was sampled to be 190 mm (longitudinal direction) × 190 mm (width direction), and only the cell portion was cut out from the obtained sample. Next, a solar cell module was produced by the method described in (4) Power generation improvement rate by modularization. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Example 2]
The reflective sheet obtained in the same manner as in Example 1 was cut into a strip shape of 190 mm (longitudinal direction) × 17 mm (width direction). The obtained strip-shaped reflection sheet is adjacent to the solar cells on both sides (for the end of the solar cell module, the end of the solar cell and the solar cell module) and parallel to the direction in which the length of the wiring material is long. And a solar cell module was produced in the same manner as in Example 1 except that the diffusion layer was laminated so as to be in contact with the front side sealing material. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Example 3]
75 parts by mass of polyethylene terephthalate, 5 parts by mass of a copolymer of polybutylene terephthalate and polytetramethylene glycol (PBT / PTMG, Toray DuPont, trade name: “Hytrel” (registered trademark)), and all dicarboxylic acids 10 parts by mass of a polyethylene terephthalate copolymer (PET / I / PEG) obtained by copolymerizing 10 mol% of isophthalic acid in a unit or diol unit and 5 mol% of polyethylene glycol having a molecular weight of 1,000, and polymethyl as an incompatible polymer After adjusting and mixing with 10 parts by mass of pentene and drying for 3 hours at a temperature of 180 ° C., it was supplied as a reflective layer material to an extruder B heated to a temperature of 270 to 300 ° C.

  Meanwhile, a polyethylene terephthalate master chip in which 70 parts by mass of a polyethylene terephthalate chip and 50% by mass of titanium oxide having a number average secondary particle size of 0.25 μm are dispersed (containing 50% by mass of titanium oxide with respect to 100% by mass of the total master chip). 30 parts by weight was vacuum-dried at a temperature of 180 ° C. for 3 hours, and then supplied to the extruder A heated to a temperature of 280 ° C. as a diffusion layer material.

  These polymers are laminated through a laminating apparatus in the order of diffusion layer / reflection layer / diffusion layer so that the thickness ratio of the film layer is 12 (diffusion layer): 126 (reflection layer): 12 (diffusion layer). The sheet was formed from a die into a sheet. Further, a reflective sheet having a thickness of 150 μm was obtained from this sheet-like material by the same process as in Example 1. A solar cell module was produced in the same manner as in Example 1 using the obtained reflection sheet. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Example 4]
A reflective sheet having a thickness of 150 μm and a solar cell module were prepared in the same manner as in Example 3 except that the polyethylene terephthalate of the reflective layer was changed to 37 parts by mass and the polymethylpentene as the incompatible polymer was changed to 48 parts by mass. Obtained. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Example 5]
70 parts by mass of polyethylene terephthalate, 5 parts by mass of a copolymer of polybutylene terephthalate and polytetramethylene glycol (PBT / PTMG, Toray DuPont, trade name: “Hytrel” (registered trademark)), and all dicarboxylic acids 10 parts by mass of a polyethylene terephthalate copolymer (PET / I / PEG) obtained by copolymerizing 10 mol% of isophthalic acid in a unit or diol unit and 5 mol% of polyethylene glycol having a molecular weight of 1,000, and polymethyl as an incompatible polymer After adjusting and mixing with 15 parts by weight of pentene and drying at a temperature of 180 ° C. for 3 hours, as a reflective layer material, it is supplied to an extruder B heated to a temperature of 270 to 300 ° C. Molded to obtain a sheet. Further, a reflective sheet (only the reflective layer portion) having a thickness of 150 μm was obtained from this sheet-like material by the same process as in Example 1. Next, a diffusion layer forming coating 1 described later was applied using a wire bar so that the coating thickness after drying was 2 μm, and dried at 100 ° C. for 60 seconds to obtain a reflective sheet. Then, it carried out similarly to Example 1, and obtained the solar cell module. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Preparation of paint for diffusion layer formation]
(I) Preparation of main agent “Harus hybrid polymer” (registered trademark) UV-G301 (solid content concentration: 40% by mass) which is a coating agent manufactured by Nippon Shokubai Co., Ltd., according to the formulation shown in the main agent column of Table 2 The color pigment and the solvent were mixed together and dispersed with a bead mill. Then, the plasticizer was added and the main ingredient of the coating material 1 for diffusion layer formation whose solid content concentration was 51 mass% was obtained.

In the main agent obtained as described above, “Desmodur” (registered trademark) N3300 (solid content concentration: 100% by mass) manufactured by Sumika Bayer Urethane Co., Ltd., which is a nurate type hexamethylene diisocyanate resin shown in Table 2. Was added so that the mass ratio of the resin layer-forming main component paint was 100/4, and a diluent (n-propyl acetate) was added so that the paint had a solid concentration of 20% by mass. The coating material 1 with a solid content concentration of 20% by mass was obtained by stirring for 15 minutes. The color pigments and plasticizers used in the preparation of the paint 1 are as follows.
White pigment: Titanium Co., Ltd. titanium oxide particles JR-709
Plasticizer: Polyester plasticizer “Polysizer” (registered trademark) W-220EL manufactured by DIC Corporation.

[Example 6]
50 parts by mass of polyethylene terephthalate chips and 30% by mass of titanium oxide having a number average secondary particle size of 0.25 μm are dispersed in a polyethylene terephthalate master chip (containing 30% by mass of titanium oxide with respect to 100% by mass of the master chip) 50 After adjusting and mixing with parts by mass and vacuum drying at 180 ° C. for 3 hours, the mixture was supplied to an extruder D heated to 280 ° C. and molded into a sheet form from a T-die to obtain a sheet-like product. Further, a diffusion layer portion of a reflective sheet having a thickness of 188 μm was obtained from this sheet-like material by the same process as in Example 1. Next, a dry laminating adhesive, which will be described later, is applied to the reflective layer portion of the reflective sheet having a thickness of 122 μm having the same composition as that of Example 4 with a wire bar, and dried at 80 ° C. for 45 seconds to dry a thickness of 5 μm. A laminate adhesive layer was formed. The two sheets thus obtained were aged at a temperature of 40 ° C. for 3 days to obtain reflective sheets. Then, it carried out similarly to Example 1, and obtained the solar cell module. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Preparation of adhesive for dry lamination]
As an adhesive for dry laminating, 36 parts by mass of a dry laminating agent “Dick Dry” (registered trademark) TAF-300 manufactured by DIC Corporation, and as a curing agent, TAF manufactured by DIC Corporation, whose main component is a hexamethylene diisocyanate resin. 3 parts by mass of Hardener AH-3 and 30 parts by mass of ethyl acetate were weighed and stirred for 15 minutes to obtain an adhesive for dry lamination having a solid content concentration of 30% by mass.

[Example 7]
50 parts by mass of polyethylene chips (containing 30% by mass of titanium oxide with respect to 100% by mass of the total amount of master chips) in which 50 parts by mass of polyethylene chips and 30% by mass of titanium oxide having a number average secondary particle size of 0.25 μm are dispersed. Were adjusted and mixed, supplied to an extruder E heated to a temperature of 180 ° C., and formed into a sheet form from a T-die to obtain a sheet-like product. Further, a diffusion layer portion of a reflection sheet having a thickness of 20 μm was obtained from this sheet-like material by the same process as in Example 1. This was laminated on the reflective layer having a thickness of 150 μm obtained in Example 4 to obtain a reflective sheet. Then, it carried out similarly to Example 1, and obtained the solar cell module. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Example 8]
The layers are laminated in the order of diffusion layer / reflective layer / diffusion layer through the laminating apparatus so that the film layer thickness ratio is 12 (diffusion layer): 76 (reflective layer): 12 (diffusion layer), and is formed into a sheet from a T-die. Except that, a reflective sheet and a solar cell module were obtained in the same manner as in Example 1. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Example 9]
The layers were laminated in the order of diffusion layer / reflective layer / diffusion layer through a laminating apparatus so that the film layer thickness ratio was 12 (diffusion layer): 276 (reflection layer): 12 (diffusion layer), and formed into a sheet from a T-die. A reflective sheet was obtained in the same manner as in Example 1 except that. Then, it carried out similarly to Example 1, and obtained the solar cell module. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Example 10]
A reflective sheet was obtained in the same manner as in Example 5 except that the coating composition for preparing the diffusion layer had the composition shown in Table 3. Then, it carried out similarly to Example 1, and obtained the solar cell module. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Example 11]
A reflective sheet for a solar cell module was obtained in the same manner as in Example 5 except that the thickness of the coating after drying the diffusion layer was 1 μm. Then, it carried out similarly to Example 1, and obtained the solar cell module. Table 1 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Comparative Example 1]
Except not using a reflective sheet, it carried out similarly to Example 1, and obtained the solar cell module. The evaluation results of the solar cell module are shown in Table 1.

[Comparative Example 2]
A solar cell module was obtained in the same manner as in Example 1 except that the reflective sheet of Example 5 (reflective sheet having no diffusion layer) without applying the paint 1 was used. Table 4 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module.

[Comparative Example 3]
Implemented except that the reflective sheet for the solar cell module of Example 3 cut to a size of 190 mm (longitudinal direction) × 190 mm (width direction) was used instead of the back sheet so that the diffusion layer was in contact with the back side sealing material. In the same manner as in Example 1, a solar cell module was obtained. Table 4 shows the physical properties of the reflective sheet and the evaluation results of the solar cell module. Although the power generation improvement rate was excellent in this comparative example, the area of the sheet required for power generation improvement was large.

1: Solar cell module 2: Reflective sheet 3: Diffusion layer 4: Reflective layer 5: Back side sealing material 6: Front side sealing material 7: Cover material 8: Solar cell 9: Back sheet 10 for solar cell module: Light receiving surface 11: A plane including solar cells and perpendicular to the light receiving surface of the solar cell module 12: Height of the solar cells

Claims (7)

  When the solar cell module is cut along a plane that includes the solar cell and is parallel to the light receiving surface of the solar cell module, the reflective sheet having a diffusion layer containing inorganic particles is located in a portion other than the solar cell. A solar cell module.   The solar cell module according to claim 1, wherein the reflection sheet is located between the front side sealing material and the back side sealing material.   The solar cell module according to claim 1, wherein the diffusion layer contains 10% by mass to 80% by mass of inorganic particles in 100% by mass of all components of the diffusion layer.   The solar cell module according to claim 1, wherein the reflective sheet has a reflective layer containing a polyester resin.   The solar cell module according to claim 4, wherein the reflective layer includes a cavity.   The solar cell module according to claim 4 or 5, wherein the reflective layer contains 10 to 50 parts by mass of an incompatible polymer with respect to 100 parts by mass of the polyester resin.   The solar cell module according to any one of claims 4 to 6, wherein the front side sealing material, the diffusion layer, the reflective layer, and the back side sealing material are positioned in this order.