JP2014183286A - Solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery module arranged to be able to prevent an end of a protection layer from being peeled off from an end of a solar battery module when shaping the solar battery module, and to withstand a stress resulting from expansion or shrinkage of the protection layer when a large change in use environment temperature is causing the protection layer to largely expand or shrink.SOLUTION: A solar battery module comprises: a surface protection layer including a resin having a Young's modulus of 1-5 GPa at 23°C; a backside protection layer; a photoelectric conversion layer; and a reinforcement layer. In the solar battery module, the photoelectric conversion layer and the reinforcement layer are sealed in by a sealant between the surface and backside protection layers. In the solar battery module, the linear expansion coefficient of the backside protection layer within a range of 0-30°C is larger than that of the reinforcement layer within a range of 0-30°C by no less than 20 ppm/K, and/or the linear expansion coefficient of the surface protection layer within a range of 0-30°C is larger than that of the reinforcement layer within a range of 0-30°C by no less than 20 ppm/K. The thickness of a peripheral portion of the solar battery module is no less than 80% the thickness of a center portion of the solar battery module.

Description

As a solar cell, for example, a solar cell using single crystal silicon or polycrystalline silicon is known.
These solar cells normally constitute a solar cell module in a state of being sealed between protective members (protective layer) with a sealing material such as EVA resin. Specifically, these solar cell modules sandwich a photoelectric conversion layer in which a plurality of solar cells are connected with an electric wire or the like between protective layers such as a surface protective layer and a back surface protective layer, wrapped in an EVA resin film, Generally, the entire module is vacuum-produced by heating and pressing with a vacuum laminator.

In recent years, polycarbonate has been adopted as a material for the protective layer in order to reduce the weight of the solar cell module and improve the transparency and mechanical strength. For example, Patent Document 1 describes a solar cell module in which a glass filler-containing polycarbonate resin molded product including a polycarbonate resin and a glass filler is used as a protective layer.
On the other hand, when polycarbonate resin is used for the protective layer, it has a smaller rigidity and larger linear expansion coefficient than conventional glass, so in the process of heat-pressure molding with a vacuum laminator together with the photoelectric conversion layer and the sealing material, The problem that the battery module is deformed by thermal stress and a non-defective product is obtained, or the risk of damaging the photoelectric conversion layer with a relatively small linear expansion coefficient due to large expansion and contraction of the protective layer when the operating environment temperature changes greatly. was there. For this reason, in Patent Document 2, a soft resin protective layer such as an acrylic resin, a polyvinyl fluoride resin, or a polyvinylidene fluoride resin is further provided as a soft resin protective layer between the protective layer and the photoelectric conversion layer. Thus, it is described that the internal thermal stress of the polycarbonate generated in the photoelectric conversion layer can be removed through a sealing material, and a solar cell module that is light in deformation and excellent in impact resistance can be obtained.

JP 2009-88072 A JP 2002-1111014 A

  Usually, these solar cell modules are formed by laminating a back surface protective layer, a photoelectric conversion layer, a surface protective layer, and the like, and sandwiching a sealing layer made of a sealing material between each layer, and a vacuum laminator However, vacuum laminators, especially diaphragm-type vacuum laminators and roll laminations, tend to concentrate stress on the peripheral edge of the solar cell module. The sealing material at the peripheral edge of the surface perpendicular to the direction flows into the center during heating and pressurization, or flows out of the module and there is little sealing material at the peripheral edge, and the adhesive strength at the end of the solar cell module decreases. The problem became clear. Therefore, when the back surface protective layer or the surface protective layer is peeled off from the end of the solar cell module or continuously used in an environment with a temperature change, the surface protective layer or the back surface protective layer is expanded and contracted. There is a concern that the peeling at the end portion is expanded due to the expansion and contraction stress.

For modules with low rigidity and small thickness, a method of aligning the overall thickness by cutting off the relatively thin peripheral edge may be taken, but for modules with high rigidity and large thickness, such measures can be taken. It is difficult.
The present invention solves the above-mentioned problem, and prevents the peeling from the end of the protective layer from the end of the solar cell module after the laminate molding, particularly when the solar cell module is molded, and changes in the use environment temperature As a solar cell module that can withstand expansion and contraction stress generated by large expansion and contraction of the protective layer when it is large, has sufficient power generation efficiency, and is used in various applications (buildings and automobiles) It aims at providing the solar cell module which does not impair an external appearance.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors focused on the relationship between the surface protective layer, the back surface protective layer, the reinforcing layer, the photoelectric conversion layer, and the linear expansion coefficient. Turned out to be caused. Further, when the reinforcing layer is provided, if the size of the reinforcing layer is smaller than the area of the protective layer laminated surface, the sealing material at the periphery of the reinforcing layer in the solar cell module becomes thin, and the portion It was found that end peeling occurred from And the dispersion | variation in the thickness of the peripheral part of a solar cell module and the thickness of a center part was reduced by adjusting the quantity of a sealing material, it discovered that the said subject could be solved, and came to complete this invention.

That is, the gist of the present invention resides in the following [1] to [5].
[1] A solar cell module in which a photoelectric conversion layer and a reinforcing layer are sealed with a sealing material between a surface protective layer and a back surface protective layer containing a resin having a Young's modulus at 23 ° C. of 1 GPa to 5 GPa. The linear expansion coefficient of the back protective layer at 0 to 30 ° C. is 20 ppm / K or more larger than the linear expansion coefficient of the reinforcing layer at 0 to 30 ° C. and / or the linear expansion of the surface protective layer at 0 to 30 ° C. The coefficient is 20 ppm / K or more larger than the linear expansion coefficient of the reinforcing layer at 0 to 30 ° C., and the thickness at the peripheral portion of the solar cell module is 80% or more of the thickness at the central portion of the solar cell module. A solar cell module characterized by.
[2] The sun according to [1], wherein the area of the laminated surface of the reinforcing layer is smaller than the area of the laminated surface of the back surface protective layer and / or the surface protective layer and is equal to or larger than the area of the photoelectric conversion layer Battery module.
[3] The sun according to [1] or [2], wherein a thickness of a sealing layer included in the solar cell module formed by the sealing material is larger at a peripheral portion than at a central portion. Battery module.
[4] Two or more reinforcing layers are included, at least one of the reinforcing layers is between the back surface protective layer and the photoelectric conversion layer, and at least one of the reinforcing layers includes the surface protective layer and the surface layer. The solar cell module according to any one of [1] to [3], wherein the solar cell module is between the photoelectric conversion layer. [5] The solar cell module according to any one of [1] to [4], wherein the thickness of the entire periphery of the solar cell module is 5 mm or more.

  According to the present invention, a solar cell module that is sufficiently durable is prevented even under an environment where the temperature change of the use environment is large, preventing peeling from the end of the protective layer from the end of the solar cell module after laminate molding. Can be obtained.

It is a schematic diagram of the cross-sectional view which shows the laminated constitution of one embodiment of the solar cell module of this invention (Example 1: Solar cell module 1). BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of one embodiment of the solar cell module of this invention (Example 1: The schematic diagram of the cross-sectional view when throwing a laminated body into a laminator before producing the solar cell module 1). It is a schematic diagram of the cross-sectional view which shows the laminated constitution of one embodiment of the solar cell module of this invention (Example 2: Solar cell module 2). It is a schematic diagram of one embodiment of the solar cell module of the present invention (Example 2: schematic diagram of a cross-sectional view when a laminated body is put into a laminator before the solar cell module 1 is created). It is a schematic diagram of the cross-sectional view which shows the layer structure of one embodiment of the solar cell module of this invention (Example 3: Solar cell module 3). It is a schematic diagram of the cross-sectional view which shows the layer structure of one embodiment of the solar cell module of this invention (Example 4: Solar cell module 4).

<Surface protective layer>
In the present invention, the surface protective layer is a layer for imparting mechanical strength, weather resistance, scratch resistance, chemical resistance, gas barrier properties and the like to the solar cell module. As the surface protective layer, a resin (hereinafter sometimes referred to as “resin (A)”) is preferably used. From the viewpoint of supplying a large amount of sunlight to the photoelectric conversion layer, the total light transmittance of the resin (A) is 80% or more, preferably 90% or more. The measuring method of a total light transmittance is based on JISK7361-1, for example.

  Examples of the resin (A) used for the surface protective layer include polycarbonate (PC), polymethyl methacrylate (PMMA), cyclic polyolefin, polystyrene, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and ethylene-tetrafluoroethylene copolymer. Examples thereof include a polymer (ETFE), polytetrafluoroethylene (PTFE), polypropylene (PP), and polyethylene (PE). Preferably, polycarbonate (PC) resin, polymethyl methacrylate (PMMA), ethylene-tetrafluoroethylene copolymer (ETFE), etc. are mentioned. The surface protective layer may have a multilayer structure using a plurality of these resins. In that case, it is preferable to provide a sealing material layer between the layers.

The linear expansion coefficient at 0 to 30 ° C. of the resin (A) is 20 to 150 ppm / K, preferably 30 to 120 ppm / K, more preferably 40 to 100 ppm / K, still more preferably 50 to 80 ppm / K. K. The method for measuring the linear expansion coefficient is, for example, ASTM.
According to D696 and the like. When the linear expansion coefficient is less than 20 ppm / K, thermal expansion / contraction stress that requires a reinforcing layer tends not to occur. On the other hand, if it exceeds 150 ppm / K, the thermal expansion / contraction stress tends to be excessive.

The Young's modulus at 23 ° C. of the resin (A) is 1 to 5 GPa, preferably 1.5 to 4 GPa, and more preferably 2 to 3 GPa or less. Examples of the Young's modulus measurement method include JIS K7161-1994 (plastic tensile modulus), JIS K7113 (plastic tensile test method), static test method (Ewing method), and ultrasonic method. If the Young's modulus exceeds 5 GPa, the heat shrinkage stress tends to be excessive. On the other hand, when it is less than 1 Gpa, the rigidity of the solar cell module of the present invention tends to be significantly reduced.
From such a viewpoint, polycarbonate (PC), polymethyl methacrylate (PMMA), and polyethylene terephthalate (PET) are more preferable.

  The method for obtaining these resins is not particularly limited, and commercially available products can be used. For example, polycarbonate plates made by Takiron Co., Ltd., “Iupilon (registered trademark)” manufactured by Mitsubishi Engineering Plastics Co., Ltd., and polymethyl methacrylate, “Acrylite (registered trademark)” manufactured by Mitsubishi Rayon Co., Ltd. “SUMIPEX (registered trademark)” manufactured by KK and ETFE include ETFE (model: 100HK-DCS) manufactured by Asahi Glass Co., Ltd.

The thickness of the resin (A) is usually 0.1 mm or more when a photovoltaic cell such as a polycrystalline silicon cell or a single crystal silicon cell is used for the photoelectric conversion layer. The thickness is preferably more than 0.5 mm, more preferably 1.0 mm or more, and even more preferably 1.5 mm or more. If it is less than 0.1 mm, the impact resistance is remarkably lowered. On the other hand, the upper limit is not particularly limited, but 5
It is preferable that it is mm or less. If the resin becomes too thick, the flexibility of the resin layer is reduced and the weight of the module is increased, so that the merit of using the solar cell module substrate as the resin is lost.

  When using photovoltaic cells such as amorphous silicon cells, microcrystalline silicon cells, compound solar cells such as CIGS, organic thin film solar cells, and dye-sensitized solar cells for the photoelectric conversion layer, usually 0.01 mm or more It is. The thickness is preferably more than 0.02 mm, more preferably 0.05 mm or more, and still more preferably 0.1 mm or more. If it is less than 0.01 mm, impact resistance and tear strength are significantly reduced. On the other hand, the upper limit is not particularly limited, but is preferably 5 mm or less. If the resin becomes too thick, the flexibility of the resin layer is reduced and the weight of the module is increased, so that the merit of using the solar cell module substrate as the resin is lost.

Moreover, the magnitude | size of the laminated surface of a surface protective layer should just have an area larger than the laminated surface of the photoelectric converting layer which has the photovoltaic cell mentioned later normally. The area of the lamination surface here means the area of the surface perpendicular to the thickness direction of the surface protective layer. A photoelectric conversion layer can fully be protected because the area of the lamination surface of a surface protective layer is larger than the area of the lamination surface of a photoelectric conversion layer.
Moreover, since a solar cell module is heated by sunlight, it is preferable that a surface protective layer has heat resistance. Therefore, the constituent material of the surface protective layer preferably has a melting point of 100 ° C. or higher, and more preferably 120 ° C. or higher. On the other hand, the upper limit of the melting point is not particularly limited, but is preferably 320 ° C. or lower from the viewpoint of secondary workability.

<Photoelectric conversion layer>
In the present invention, the photoelectric conversion layer is a layer that generates power based on sunlight incident from the light receiving surface side. The photoelectric conversion layer only needs to be capable of converting light energy into electric energy and taking out the electric energy obtained by the conversion to the outside. The photoelectric conversion layer includes one or more solar cells, and the photoelectric conversion layer may be formed by connecting a plurality of solar cells with an electric wire (interconnector). The electric energy obtained in the photoelectric conversion layer can be taken out via an external converter through a collecting wire.

In the present invention, the material of the electric wire is not particularly limited, but it is preferable to use a highly conductive metal material. Specifically, silver, copper, aluminum, copper alloy, aluminum alloy, copper plated with tin, lead-free solder-coated copper wire, or the like can be used.
Therefore, as a photoelectric conversion layer, a solar battery cell in which a power generation layer is sandwiched between a pair of electrodes, a solar battery cell in which a stacked body of a power generation layer and another layer (buffer layer, etc.) is sandwiched between a pair of electrodes, and the like It is possible to use those including a plurality of such connected in series or / and in parallel.

  Various power generation layers can be adopted as the photoelectric conversion layer, but the power generation layer is thin film single crystal silicon, thin film polycrystalline silicon, amorphous silicon, microcrystalline silicon, CdTe, Cu-In- (Ge). It is preferable to use an inorganic semiconductor material such as Se, an organic dye material such as a black die, or an organic semiconductor material such as a conjugated polymer / fullerene, but from the viewpoint of power generation efficiency, thin film single crystal silicon or thin film polycrystalline silicon Is more preferable. For example, commercially available silicon solar cells may be used, and examples include solar cells such as those manufactured by Q-Cells, First Solar, Suntech, Sharp, Shinsung, Gintech, and Sunpower. .

Further, a multi-junction photoelectric conversion layer, a HIT photoelectric conversion layer, or the like may be employed.
In order to realize higher power generation efficiency, it is preferable to provide a sufficient light confinement structure, such as forming an uneven structure on the surface of the power generation layer or on the photoelectric conversion layer substrate that is installed as necessary.
If the power generation layer is an amorphous silicon layer, a photoelectric conversion layer that has a large optical absorption coefficient in the visible region and can sufficiently absorb sunlight even with a thin film having a thickness of about 1 μm can be realized. In addition, amorphous silicon, microcrystalline silicon, inorganic semiconductor materials, organic dye materials, and organic semiconductor materials are non-crystalline materials or materials with low crystallinity, and thus have resistance to deformation. Therefore, if an amorphous silicon layer is provided as a power generation layer, a solar cell module that is particularly lightweight and has a certain degree of resistance to deformation can be realized.

  If an inorganic semiconductor material (compound semiconductor) is used for the power generation layer, a photoelectric conversion layer with high power generation efficiency can be realized. From the viewpoint of power generation efficiency (photoelectric conversion efficiency), the power generation layer is preferably a chalcogenide-based power generation layer containing a chalcogen element such as S, Se, Te, etc. I-III-VI2 group semiconductor system (chalcopyrite system) ) More preferably as a power generation layer, a Cu-III-VI2 semiconductor power generation layer using Cu as a group I element, particularly a CIS semiconductor [CuIn (Se1-ySy) 2; 0 ≦ y ≦ 1] layer In addition, it is desirable to use a CIGS-based semiconductor [Cu (In1-xGax) (Se1-ySy) 2; 0 <x <1, 0 ≦ y ≦ 1] layer.

Even when a dye-sensitized power generation layer composed of a titanium oxide layer, an electrolyte layer, or the like is employed as the power generation layer, a photoelectric conversion layer with high power generation efficiency can be realized.
As the power generation layer, an organic semiconductor layer (a layer including a p-type semiconductor and an n-type semiconductor) can be employed. In addition, as a p-type semiconductor which can comprise an organic-semiconductor layer, a purophylline compound such as tetrabenzoporphyrin, tetrabenzocopper porphyrin, tetrabenzozinc porphyrin; a phthalocyanine compound such as phthalocyanine, copper phthalocyanine, zinc phthalocyanine; a polycene of tetracene or pentacene; Examples include oligothiophenes such as sexithiophene and derivatives containing these compounds as a skeleton. Furthermore, examples of p-type semiconductors that can form the organic semiconductor layer include polymers such as polythiophene including poly (3-alkylthiophene), polyfluorene, polyphenylene vinylene, polytriallylamine, polyacetylene, polyaniline, polypyrrole, and the like. .

  In addition, n-type semiconductors that can constitute the organic semiconductor layer include fullerenes (C60, C70, C76); octaaporphyrins; perfluoro compounds of the above p-type semiconductors; naphthalenetetracarboxylic anhydrides, nafullerenetetracarboxylics. Examples thereof include aromatic carboxylic acid anhydrides such as acid diimide, perylene tetracarboxylic acid anhydride, and perylene tetracarboxylic acid diimide, and imide compounds thereof; and derivatives containing these compounds as a skeleton.

  Further, as a specific configuration example of the organic semiconductor layer, a bulk heterojunction type having a layer (i layer) in which a p-type semiconductor and an n-type semiconductor are phase-separated in the layer, and a layer (p layer) each including a p-type semiconductor. And a layered type (hetero pn junction type), a Schottky type, and a combination thereof, in which layers containing an n-type semiconductor (n layer) are stacked.

Each electrode of the solar battery cell can be formed using one or more arbitrary materials having conductivity. Examples of the electrode material (electrode constituent material) include metals such as platinum, gold, silver, aluminum, chromium, nickel, copper, titanium, magnesium, calcium, barium, sodium, and alloys thereof; indium oxide and tin oxide Metal oxides such as, or alloys thereof (ITO: indium tin oxide); conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene; acids such as hydrochloric acid, sulfuric acid, sulfonic acid, Containing dopants such as Lewis acids such as FeCl3, halogen atoms such as iodine, metal atoms such as sodium and potassium; conductive particles such as metal particles, carbon black, fullerene and carbon nanotubes in a matrix such as a polymer binder Examples include a dispersed conductive composite material.

This electrode material is preferably a material suitable for collecting holes or electrons. Examples of electrode materials suitable for collecting holes (that is, materials having a high work function) include Au, Ag, Cu, Al, ITO, IZO, and ZnO2. Moreover, Al can be illustrated as an electrode material suitable for electron collection (that is, a material having a low work function).
There is no restriction | limiting in particular also in the formation method of an electrode. Therefore, the electrodes can be formed by a dry process such as vacuum deposition or sputtering, or can be formed by a wet process using a conductive ink or the like. As the conductive ink, an arbitrary one (conductive polymer, metal particle dispersion, etc.) can be used.

  Each electrode of the solar battery cell may be substantially the same size as the power generation layer or may be smaller than the power generation layer. However, when the electrode on the light-receiving surface side of the solar battery cell is relatively large (the area is not sufficiently small compared to the power generation layer area), the electrode should be transparent ( The transmissivity of the light having a wavelength (for example, 300 to 1200 nm, preferably 500 to 800 nm) at which the electrode, particularly the power generation layer can be efficiently converted into electric energy, is relatively high (for example, 50% or more). ) Electrode. Examples of transparent electrode materials include oxides such as ITO and IZO (indium oxide-zinc oxide); metal thin films, and the like.

  In addition, the thickness of each electrode of the solar battery cell and the thickness of the power generation layer can be determined based on the required output, etc., but if it is too thick, the electrical resistance increases, and if it is too thin, the durability is high. May fall.

[Photoelectric conversion layer substrate]
A photoelectric conversion layer base material is a member in which a photovoltaic cell is formed on one surface thereof as needed. Therefore, it is desired that the photoelectric conversion layer base material has a relatively high mechanical strength, is excellent in weather resistance, heat resistance, water resistance, and the like, and is lightweight. It is also desirable that the photoelectric conversion layer base material has a certain degree of resistance to deformation. On the other hand, if the physical properties (for example, linear expansion coefficient, melting point, etc.) of the formed photovoltaic cell are significantly different, there is a risk of distortion or peeling at the interface after formation.

Therefore, as the photoelectric conversion layer substrate, it is preferable to employ a metal foil, a resin film having a melting point of 85 ° C. or higher or no melting point, and several metal foil / resin film laminates.
Examples of the metal foil that can be used as the photoelectric conversion layer substrate (or a component thereof) include foils made of aluminum, stainless steel, gold, silver, copper, titanium, nickel, iron, and alloys thereof.

  In addition, resin films having a melting point of 85 ° C. or higher or no melting point include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycarbonate, polyacetal, acrylic resin, polyamide resin, ABS resin. , ACS resin, AES resin, ASA resin, copolymers thereof, fluorine resin such as PVF, silicone resin, cellulose, nitrile resin, phenol resin, polyurethane, ionomer, polybutadiene, polybutylene, polymethylpentene, polyvinyl alcohol, polyarylate Examples thereof include films made of polyetheretherketone, polyetherketone, polyethersulfone, polyimide, and the like. From the viewpoint of productivity of the metal resin composite substrate, the resin is preferably a thermoplastic resin. The resin film used as the power generation element substrate is a film in which inorganic substances such as antimony oxide, antimony hydroxide, barium borate, glass fiber, organic fibers, carbon fibers, etc. are dispersed in the resin as described above. There may be.

  The reason why the melting point of the resin film used as the photoelectric conversion layer substrate (or its constituent elements) is preferably 85 ° C. or higher is that when the melting point is excessively low, the photoelectric conversion is performed under the normal use environment of the solar cell module. This is because the layer base material is deformed and may damage the photoelectric conversion layer.

  Accordingly, the melting point of the resin film used as the photoelectric conversion layer substrate (or its constituent elements) is more preferably 100 ° C. or higher, further preferably 120 ° C. or higher, and more preferably 150 ° C. or higher. Particularly preferred is 180 ° C. or higher. The thermal expansion coefficient of the photoelectric conversion layer is not particularly limited, but is preferably 40 ppm / K or less, more preferably 35 ppm / K or less, and particularly preferably 30 ppm / K or less. The measuring method of the thermal expansion coefficient is, for example, according to ASTM D696. When the thermal expansion coefficient exceeds 40 ppm / K, deformation due to temperature change is large, and therefore, it tends to be liable to fail under heating / cooling processes or actual use conditions. On the other hand, the lower limit is not particularly limited, but is usually −5 ppm / K or more, preferably 0 ppm / K or more.

<Back side protective layer>
As the back surface protective layer of the solar cell module of the present invention, a resin (hereinafter sometimes referred to as “resin (B)”) material is preferably used.
Examples of such resins include polycarbonate (PC) resin, polymethyl methacrylate (PMMA), glass epoxy multilayer material, fiber reinforced plastic (FRP), cyclic polyolefin, polystyrene, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). ), Polyimide (PI), ethylene-tetrafluoroethylene copolymer (ETFE), and the like. Preferred examples include polycarbonate (PC) resin, polymethyl methacrylate (PMMA), glass epoxy multilayer material, polyethylene terephthalate (PET), and ethylene-tetrafluoroethylene copolymer (ETFE).

The linear expansion coefficient at 0 to 30 ° C. of the resin (B) is 20 to 150 ppm / K, preferably 30 to 120 ppm / K, more preferably 40 to 100 ppm / K, still more preferably 50 to 80 ppm / K. K. The method for measuring the linear expansion coefficient is, for example, ASTM.
According to D696 and the like. When the linear expansion coefficient is less than 20 ppm / K, thermal expansion / contraction stress that requires a reinforcing layer tends not to occur. On the other hand, if it exceeds 150 ppm / K, the thermal expansion / contraction stress tends to be excessive.

The Young's modulus at 23 ° C. of the resin (B) is 1 to 5 GPa, preferably 1.5 to 4 GPa, and more preferably 2 to 3 GPa or less. Examples of the Young's modulus measurement method include JIS K7161-1994 (plastic tensile modulus), JIS K7113 (plastic tensile test method), static test method (Ewing method), and ultrasonic method. If the Young's modulus exceeds 5 GPa, the heat shrinkage stress tends to be excessive. On the other hand, when it is less than 1 Gpa, the rigidity of the solar cell module of the present invention tends to be significantly reduced.
From such a viewpoint, polycarbonate (PC), polymethyl methacrylate (PMMA), and polyethylene terephthalate (PET) are more preferable.

The back surface protective layer may have a multilayer structure using a plurality of these resins. In that case, it is preferable to provide a sealing material layer between the layers.
As resin (B) used for a back surface protective layer, the same kind as resin (A) may be different, but it is preferable to use the same resin. As a combination of the resin (A) and the resin (B), when the resin (A) is a PC resin and the resin (B) is a PC resin, the resin (A) is a PMMA resin and the resin (B) is PMMA. In the case of a resin, it is preferable that the resin (A) is a PC resin and the resin (B) is a PMMA resin, and the resin (A) is a PMMA resin and the resin (B) is a PC resin. A particularly preferred combination is when the resin (A) is a PC resin and the resin (B) is a PC resin.

  The thickness of the resin (B) is usually 0.1 mm or more when a photovoltaic cell such as a polycrystalline silicon cell or a single crystal silicon cell is used for the photoelectric conversion layer. The thickness is preferably more than 0.5 mm, more preferably 1.0 mm or more, and even more preferably 1.5 mm or more. If it is less than 0.1 mm, the impact resistance is remarkably lowered. On the other hand, the upper limit is not particularly limited, but is preferably 5 mm or less. If the resin becomes too thick, the flexibility of the resin layer is reduced and the weight of the module is increased, so that the merit of using the solar cell module substrate as the resin is lost.

  When using photovoltaic cells such as amorphous silicon cells, microcrystalline silicon cells, compound solar cells such as CIGS, organic thin film solar cells, and dye-sensitized solar cells for the photoelectric conversion layer, usually 0.01 mm or more It is. The thickness is preferably more than 0.02 mm, more preferably 0.05 mm or more, and still more preferably 0.1 mm or more. If it is less than 0.01 mm, impact resistance and tear strength are significantly reduced. On the other hand, the upper limit is not particularly limited, but is preferably 5 mm or less. If the resin becomes too thick, the flexibility of the resin layer is reduced and the weight of the module is increased, so that the merit of using the solar cell module substrate as the resin is lost.

Since the solar cell module is heated by sunlight, the back surface protective layer preferably has heat resistance. Therefore, the constituent material of the back surface protective layer preferably has a melting point of 100 ° C. or higher, and more preferably 120 ° C. or higher. On the other hand, the upper limit of the melting point is not particularly limited, but is preferably 320 ° C. or lower from the viewpoint of secondary workability.
Further, in order to balance the rigidity of the front and back protective layers so that it is difficult to apply a load to the photoelectric conversion layer, the thickness of the resin (B) is preferably the same as that of the resin (A). The thickness is more preferably in the range of 0.2 to 5 times, more preferably in the range of 0.3 to 3 times, and still more preferably in the range of 0.5 to 2 times.

<Reinforcing layer>
In the solar cell module of the present invention, the reinforcing layer is a layer disposed between the surface protective layer and the back surface protective layer, and is caused by heat shrinkage stress from the surface protective layer and the back surface protective layer generated during cooling after thermal lamination. It is a layer which has a function which prevents that the photovoltaic cell of a photoelectric converting layer is damaged, or a crack arises in a photovoltaic cell.

The number of reinforcing layers included in the solar cell module of the present invention is not particularly limited, but is usually 1 to 2 layers. In addition, at least one of the reinforcing layers is between the surface protective layer and the photoelectric conversion layer, but is preferably between the photoelectric conversion layer and the back surface protective layer.
In the reinforcing layer of the present invention, the area of the laminated surface (the area of the surface perpendicular to the thickness direction) is preferably larger than the area of the laminated surface of the photoelectric conversion layer. By setting it as such an aspect, buckling of the current collection line which exists in the peripheral part of a photoelectric converting layer can be suppressed. Moreover, it is preferable that it is smaller than the area of the laminated surface of a surface protective layer and a back surface protective layer. The reason for this is that at the edge of the solar cell module where stress generated inside the module due to the thermal contraction difference between the layers tends to concentrate, the stress is applied to the end by increasing the thickness of the sealing layer with excellent flexibility. It can avoid concentrating and can suppress peeling from the edge part of a reinforcement layer.

The material of the reinforcing layer is not particularly limited as long as it has optical transparency, and examples thereof include thin plate glass, high-strength plastic (stretched polyethylene terephthalate (stretched PET), stretched polyethylene naphthalate (stretched PEN)), and the like. . Moreover, when arrange | positioning a reinforcement layer in the light-receiving surface side rather than a photoelectric converting layer, it is necessary to use a material with high light transmittance. Examples of such materials include glass, stretched PET, stretched PEN, and thin float glass.

The thickness of the reinforcing layer is not particularly limited, but is usually 10 μm or more, preferably 50 μm or more, and more preferably 100 μm or more. On the other hand, the upper limit is usually 1000 μm or less, preferably 500 μm or less.
Moreover, the reinforcement layer can also use the thing of the same or different material in combination of 2 or more layers, and can reinforce the reinforcement effect.

  The reinforcing layer has a linear expansion coefficient at 0 to 30 ° C. of 0 to 50 ppm / K, preferably 1 to 40 ppm / K, more preferably 2 to 30 ppm / K. As this value decreases, the solar cell damage due to heat shrinkage stress from the surface protective layer tends to decrease. When the linear expansion coefficient exceeds 50 ppm / K, thermal deformation of the reinforcing layer itself tends to increase and the reinforcing effect tends to decrease. On the other hand, when it is less than 0 ppm / K, it may be smaller than the linear expansion coefficient of the photoelectric conversion layer, which may have an adverse effect.

  The need for uniform thickness of the solar cell module according to the present invention is particularly important when the linear expansion coefficient of the reinforcing layer is large from the linear expansion coefficient of the surface protective layer and / or the back surface protective layer. . That is, the linear expansion coefficient of the reinforcing layer in the present invention is preferably 20 ppm / K or less, more preferably 30 ppm / K or less, and more preferably 40 ppm / K than the linear expansion coefficient of the surface protective layer and / or the back protective layer. It is still more preferable that it is small. On the other hand, if the difference in coefficient of linear expansion between the surface protective layer and / or the back surface protective layer becomes too large, internal strain and internal stress accompanying the temperature change become too large, and peeling at the edges and inside tends to occur. . From such a viewpoint, the linear expansion coefficient of the reinforcing layer is preferably not less than 100 ppm / K, more preferably not less than 80 ppm / K, and more preferably 70 ppm / K than the linear expansion coefficient of the surface protective layer and / or the back surface protective layer. More preferably, it is not smaller than K.

Further, the reinforcing layer has a Young's modulus at 23 ° C. of 1 to 200 GPa, preferably 6 to 150 GPa, more preferably 10 to 120 GPa, and further preferably 20 to 100 GPa. As this value increases, the reinforcing effect tends to increase. When the Young's modulus is less than 1 GPa, the reinforcing effect tends to decrease.
The Young's modulus of the reinforcing layer may be small with respect to the materials (A) and (B) constituting the surface protective layer and the back protective layer, but the same or larger is the viewpoint that ensures the reinforcing effect. To more preferable.

<Encapsulant layer>
The solar cell module of the present invention is formed by sealing the reinforcing layer and the photoelectric conversion layer. When these are sealed, a sealing material is present so as to cover the photoelectric conversion layer and the reinforcing layer. Since a sealing material is used so that a photoelectric converting layer may be covered, the layer by a sealing material is formed between a surface protective layer and a photoelectric converting layer, and between a back surface protective layer and a photoelectric converting layer. Moreover, a sealing material layer is formed also when providing a reinforcement layer between a reinforcement layer and a surface protective layer, or between a photoelectric converting layer and a back surface protective layer. The sealing material is used to integrate the constituent layers (surface protective layer, photoelectric conversion layer, back surface protective layer, insulating layer, damage prevention layer, etc.) of the solar cell module and reinforce the photoelectric conversion layer. It is a component. Since the photoelectric conversion layer is thinner and weaker than the surface protective layer and the back surface protective layer, the strength of the solar cell module tends to be weak, but the strength can be kept high by the sealing material.

In addition, the sealing material is preferably high in strength from the viewpoint of maintaining the strength of the solar cell module. Specifically, the sealing material is generally related to the strength of the surface protective layer and the back surface protective layer other than the sealing material. However, it is desirable that the entire solar cell module has good durability and has a strength that does not cause internal peeling even after long-term use.
Further, the sealing material is preferably one that transmits visible light from the viewpoint of not hindering light absorption of the photoelectric conversion layer. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

  Furthermore, since the solar cell module is often heated by receiving light, it is preferable that the sealing material also has heat resistance. From this viewpoint, the melting point of the constituent material of the sealing material is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably It is 300 degrees C or less. By increasing the melting point, it is possible to reduce the possibility of the sealing material melting and deteriorating when the solar cell module is used.

  As a material which comprises a sealing material, what used the ethylene-vinyl acetate copolymer (EVA) resin composition for the film (EVA film) etc. can be used, for example. In order to improve weather resistance, the EVA film is usually blended with a crosslinking agent to form a crosslinked structure. As the crosslinking agent, an organic peroxide that generates radicals at 100 ° C. or higher is generally used. Examples of such an organic peroxide include 2,5-dimethylhexane; 2,5-dihydroperoxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; Di-t-butyl peroxide or the like can be used. The compounding amount of these organic peroxides is usually 5 parts by weight or less, preferably 3 parts by weight or less, and usually 1 part by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a crosslinking agent and it may use 2 or more types together by arbitrary combinations and a ratio.

  This EVA resin composition may contain a silane coupling agent for the purpose of improving the adhesive strength. Examples of the silane coupling agent used for this purpose include γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyl-tri- (β-methoxyethoxy) silane; γ-methacryloxypropyltri Methoxysilane; β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane and the like can be mentioned. The compounding amount of these silane coupling agents is usually 5 parts by weight or less, preferably 2 parts by weight or less, and usually 0.1 parts by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a silane coupling agent and it may use 2 or more types together by arbitrary combinations and a ratio.

  Furthermore, in order to improve the gel fraction of the EVA resin and improve the durability, a crosslinking aid may be included in the EVA resin composition. Examples of the crosslinking aid provided for this purpose include monofunctional crosslinking aids such as trifunctional crosslinking aids such as triallyl isocyanurate and triallyl isocyanate. The amount of these crosslinking aids is usually 10 parts by weight or less, preferably 5 parts by weight or less, and usually 1 part by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a crosslinking adjuvant, and 2 or more types may be used together by arbitrary combinations and a ratio.

  Furthermore, for the purpose of improving the stability of the EVA resin, the EVA resin composition may contain, for example, hydroquinone; hydroquinone monomethyl ether; p-benzoquinone; methyl hydroquinone. These compounding quantities are normally 5 weight part or less with respect to 100 weight part of EVA resin.

However, since the EVA resin cross-linking process requires a relatively long time of about 1 to 2 hours, it may cause a reduction in the production rate and production efficiency of the solar cell module. In addition, when used for a long period of time, the decomposition gas (acetic acid gas) of the EVA resin composition or the vinyl acetate group of the EVA resin itself may adversely affect the photoelectric conversion layer and reduce the power generation efficiency. Therefore, as the sealing material, a copolymer film made of a propylene / ethylene / α-olefin copolymer can be used in addition to the EVA film. As this copolymer, the thermoplastic resin composition with which the following component 1 and the component 2 were mix | blended is mentioned, for example.
Component 1: The propylene-based polymer is usually 0 part by weight or more, preferably 10 parts by weight or more, and usually 70 parts by weight or less, preferably 50 parts by weight or less.
-Component 2: A soft propylene-type copolymer is 30 weight part or more, Preferably it is 50 weight part or more, and is 100 weight part or less normally, Preferably it is 90 weight part or less.

The total amount of component 1 and component 2 is 100 parts by weight. As described above, when component 1 and component 2 are in a preferred range, the moldability of the encapsulant into a sheet is good, and the resulting encapsulant has good heat resistance, transparency and flexibility, It is suitable for a solar cell module.
Hereinafter, component 1 and component 2 will be described in detail.

[Component 1]
Component 1 is a propylene-based polymer, and examples thereof include a propylene homopolymer; a copolymer of propylene and at least one α-olefin having 2 to 20 carbon atoms other than propylene. Here, as the α-olefin having 2 to 20 carbon atoms other than propylene, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-octene, Examples include decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene. Among these, ethylene or an α-olefin having 4 to 10 carbon atoms is preferable. In addition, alpha-olefin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

These α-olefins may form a random copolymer with propylene or a block copolymer. The proportion of the constituent units derived from these α-olefins is usually 35 mol% or less, preferably 30 mol% or less in the polypropylene.
Component 1 has a melt flow rate (MFR) measured at 230 ° C. and a load of 2.16 kg in accordance with ASTM D 1238, usually 0.01 g / 10 min or more, preferably 0.05 g / 10 min or more. Usually, it is 1000 g / 10 min or less, preferably 100 g / 10 min or less.

The melting point observed by the differential scanning calorimeter of component 1 is usually 100 ° C. or higher, preferably 110 ° C. or higher, and is usually 160 ° C. or lower, preferably 150 ° C. or lower.
Component 1 can use either an isotactic structure or a syndiotactic structure, but the isotactic structure is preferred in terms of heat resistance and the like.
Further, as the component 1, a plurality of propylene-based polymers can be used in combination as necessary. For example, two or more types of components having different melting points and rigidity can be used.

[Component 2]
Component 2 is a soft propylene-based copolymer, and examples thereof include a copolymer of propylene and at least one α-olefin having 2 to 20 carbon atoms other than propylene.
Component 2 has a Shore A hardness of usually 30 or more, preferably 35 or more, and usually 80 or less, preferably 70 or less.

Furthermore, the melting point observed with the differential scanning calorimeter DSC of component 2 is less than 100 ° C. or no melting point is observed. Here, that the melting point is not observed means that a crystal melting peak having a heat of crystal melting of 1 J / g or more is not observed in the range of −150 to 200 ° C.
In Component 2, the α-olefin used as a comonomer is preferably, for example, ethylene and / or an α-olefin having 4 to 20 carbon atoms. In addition, alpha-olefin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

Component 2 contains propylene-derived units usually 45 mol% or more, preferably 56 mol% or more, and usually 92 mol% or less, preferably 90 mol% or less, and usually contains α-olefin-derived units used as a comonomer. 8 mol% or more, preferably 10 mol% or more, and usually 55 mol% or less, preferably 44 mol% or less.
Component 2 has a melt flow rate (MFR) measured at 230 ° C. and a load of 2.16 kg, usually 0.01 g / 10 min or more, preferably 0.05 g / 10 min or more, in accordance with ASTM D 1238. In addition, it is usually 100 g / 10 min or less, preferably 50 g / 10 min or less.

  Component 2 is based on JIS K6301, using a JIS No. 3 dumbbell, span: 30 mm, tensile speed: 30 mm / min, measured at 23 ° C., stress at 100% strain (M100) is usually 4 MPa. Hereinafter, it is preferably 3 MPa or less, more preferably 2 MPa or less. When the soft propylene copolymer is in such a range, the flexibility, transparency, and rubber elasticity are excellent.

Component 2 has a crystallinity measured by X-ray diffraction of usually 20% or less, preferably 15% or less, and usually 0% or more.
Component 2 has a single glass transition temperature Tg, and the glass transition temperature Tg measured by a differential scanning calorimeter (DSC) is usually in the range of −10 ° C. or lower, preferably −15 ° C. or lower. Is desirable. When the glass transition temperature Tg of Component 2 is within the above range, the cold resistance and low temperature characteristics are excellent.

The molecular weight distribution (Mw / Mn, polystyrene conversion, Mw: weight average molecular weight, Mn: number average molecular weight) measured by GPC of Component 2 is preferably 4.0 or less, more preferably 3.0 or less, and further Preferably it is 2.5 or less.
Preferred specific examples of component 2 include the following propylene / ethylene / α-olefin copolymers. By using such a propylene / ethylene / α-olefin copolymer, a sealing material having good flexibility, heat resistance, mechanical strength, solar cell sealing property and transparency can be obtained. Here, solar cell sealing property means that the cracking rate of the cell at the time of filling a photoelectric converting layer can be reduced by favorable softness | flexibility.

  As propylene / ethylene / α-olefin copolymer, propylene-derived structural units are usually 45 mol% or more, preferably 56 mol% or more, more preferably 61 mol% or more, and usually 92 mol% or less, preferably 90 mol% or less, more preferably 86 mol% or less, and further ethylene-derived structural units are usually 5 mol% or more, preferably 8 mol% or more, and usually 25 mol% or less, preferably 14 mol% or less, more Preferably, it contains 14 mol% or less, and the structural unit derived from an α-olefin having 4 to 20 carbon atoms is usually 3 mol% or more, preferably 5 mol% or more, more preferably 6 mol% or more, and usually 30 mol% or less. , Preferably those containing 25 mol% or less. With regard to α-olefins, 1-butene is particularly preferred.

A propylene / ethylene / α-olefin copolymer (component 2) containing a propylene-derived structural unit, an ethylene-derived structural unit, and a structural unit derived from an α-olefin having 4 to 20 carbon atoms in the above amount is propylene. The compatibility with the system polymer (component 1) becomes good, and the obtained sealing material exhibits sufficient transparency, flexibility, heat resistance and scratch resistance.
The thermoplastic resin composition in which the above components 1 and 2 are blended has a melt flow rate (
ASTM D 1238, 230 degrees, load 2.16 kg) is usually 0.0001 g / 10 min or more, and usually 1000 g / 10 min or less, preferably 900 g / 10 min or less, more preferably 800 g / 10 min or less. It is.

The melting point of the thermoplastic resin composition containing component 1 and component 2 is usually 100 ° C. or higher, preferably 110 ° C. or higher. Moreover, it is 140 degrees C or less normally, Preferably it is 135 degrees C or less.
Density of The thermoplastic resin composition Components 1 and 2 were compounded is preferably from 0.98 g / cm ³ or less, more preferably 0.95 g / cm ³ or less, more preferably 0.94 g / cm ³ or less .

In this encapsulant, a coupling agent can be blended into the component 1 and component 2 as an adhesion promoter for plastics and the like. As the coupling agent, silane, titanate, and chromium coupling agents are preferably used, and a silane coupling agent (silane coupling agent) is particularly preferably used.
Known silane coupling agents can be used and are not particularly limited. For example, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxy-ethoxysilane), γ-glycidoxypropyl-tri Examples include piltrimethoxysilane and γ-aminopropyltriethoxysilane. In addition, 1 type may be used for a coupling agent and it may use 2 or more types together by arbitrary combinations and a ratio.

These are usually 0.1 parts by weight or more, usually 5 parts by weight or less, preferably 100 parts by weight of the silane coupling agent, based on 100 parts by weight of the thermoplastic resin composition (total amount of Component 1 and Component 2). It is desirable to contain 3 parts by weight or less.
The coupling agent may be grafted to the thermoplastic resin composition using an organic peroxide. In this case, it is desirable that 0.1 to 5 parts by weight of the coupling agent is included with respect to 100 parts by weight of the thermoplastic resin composition (total amount of component 1 and component 2). Even if a silane-grafted thermoplastic resin composition is used, the same or better adhesiveness as that of the silane coupling agent blend can be obtained for glass and plastic.

When the organic peroxide is used, the organic peroxide is usually 0.001 part by weight or more, preferably 0.01 part by weight with respect to 100 parts by weight of the thermoplastic resin composition (total amount of Component 1 and Component 2). Part or more, and usually 5 parts by weight or less, preferably 3 parts by weight or less.
Known organic peroxides can be used and are not particularly limited. Examples thereof include dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, and dibenzoylperoxide. Examples thereof include oxide, t-amylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, and t-butylperoxymaleic acid. In addition, an organic peroxide may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

Moreover, the copolymer which consists of an ethylene-alpha-olefin copolymer can also be used as a sealing material. Examples of the copolymer include a laminate film having a hot tack property of 5 to 25 ° C., which is formed by laminating a resin composition for a sealing material comprising the following components A and B and a substrate.
Component A: ethylene resin.
Component B: a copolymer of ethylene and an α-olefin having the following properties (a) to (d).
(A) The density is 0.86 to 0.935 g / cm ³ .
(B) Melt flow rate (MFR) is 1 to 50 g / 10 min.
(C) There is one peak in the elution curve obtained by temperature rising elution fractionation (TREF); the peak temperature is 100 ° C. or lower.
(D) The integrated elution amount by temperature rising elution fractionation (TREF) is 90% or more at 90 ° C.

(A) Component A (ethylene-based resin)
Examples of the ethylene-based resin as the component A constituting the resin composition for a sealing material include a high-pressure low-density polyethylene, an ethylene / vinyl acetate copolymer, an ethylene / acrylic acid copolymer produced by a so-called radical polymerization method. Examples thereof include an ethylene / acrylic acid ester copolymer and an ethylene / vinyl fluoride copolymer. Moreover, the polymer or copolymer which has ethylene as a main component, such as what is called linear low density polyethylene and high density polyethylene manufactured by the ionic polymerization method, is also mentioned. Among these, ethylene / vinyl acetate copolymer and high pressure method low density polyethylene are preferable. In addition, these may use 1 type and may use 2 or more types together by arbitrary combinations and ratios.
When the ethylene resin as component A constituting the resin composition for a sealing material is an ethylene / vinyl acetate copolymer, those having the following properties are suitable.

(I) Melt flow rate (MFR)
JIS of ethylene / vinyl acetate copolymer as component A constituting resin composition for encapsulant
The MFR (melt flow rate: melt flow rate) by K7210 is usually 1 g / 10 minutes or more, preferably 2 g / 10 minutes or more, more preferably 3 g / 10 minutes or more, and usually 50 g / 10 minutes. Hereinafter, it is preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less. Increasing the MFR tends to increase transparency when blended with the component B, and decreasing the MFR tends to facilitate molding.

(Ii) Vinyl acetate content The vinyl acetate content of the ethylene / vinyl acetate copolymer as component A constituting the resin composition for a sealing material is usually 3% by weight or more, preferably 4% by weight or more, more preferably 5%. It is usually not more than 30% by weight, preferably not more than 20% by weight, more preferably not more than 15% by weight. Increasing the vinyl acetate content tends to increase heat sealability, and reducing the vinyl acetate content can suppress stickiness of the sealing material.
When the ethylene-based resin as component A constituting the resin composition for a sealing material is a high-pressure method low-density polyethylene, those having the following properties are suitable.

(I) Melt flow rate (MFR)
The MFR (melt flow rate: melt flow rate) of JIS K7210 of the high-pressure low-density polyethylene as component A constituting the resin composition for a sealing material is usually 1 g / 10 min or more, preferably 2 g / 10. Min. Or more, more preferably 3 g / 10 min or more, and usually 50 g / 10 min or less, preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less. It tends to be easy to extrude by increasing the MFR, and by reducing the MFR, the film becomes too soft and does not easily sag, and the moldability increases.

(Ii) Density by JIS K7112 of high-pressure low-density polyethylene as component A constituting the density encapsulant resin composition is usually 0.915 g / cm ³ or more, preferably 0.916 g / cm ³ or more, more preferably at 0.917 g / cm ³ or more and usually 0.93 g / cm ³ or less, preferably 0.925 g / cm ³ or less, more preferably 0.923 g / cm ³ or less. Increasing the density tends to suppress stickiness of the sealing material, and decreasing the density tends to increase heat sealability.
As the high-pressure method low-density polyethylene as component A constituting the resin composition for a sealing material, those exhibiting the above physical properties can be appropriately selected from commercially available products.
(B) Component B (ethylene / α-olefin copolymer)
Component B constituting the resin composition for a sealing material is an ethylene / α-olefin copolymer other than Component A. Component B preferably has the following properties.

(I) Density The density according to JlS K7112 of the ethylene / α-olefin copolymer as component B constituting the resin composition for a sealing material is usually 0.86 g / cm ³ or more, preferably 0.87 g /
cm ³ or more, more preferably 0.88 g / cm ³ or more, and usually 0.935 g / cm ³ or less, preferably 0.915 g / cm ³ or less, more preferably 0.91 g / cm ³ or less. By increasing the density, stickiness when used as a film tends to be suppressed, and by decreasing the density, heat sealability tends to increase.

(Ii) Melt flow rate (MFR)
The MFR (melt flow rate: melt flow rate) according to JLS K7210 of the ethylene / α-olefin copolymer as component B constituting the resin composition for a sealing material is usually 1 g / 10 min or more, preferably It is 2 g / 10 min or more, more preferably 3 g / 10 min or more, and is usually 50 g / 10 min or less, preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less. It tends to be easy to extrude by increasing the MFR, and by reducing the MFR, the film becomes too soft and does not easily sag, and the moldability increases.

  Here, the α-olefin is preferably an α-olefin having 4 to 40 carbon atoms. Among them, among α-olefins, those having usually 4 or more, preferably 6 or more, and usually 12 or less, preferably 10 or less are desirable. For example, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methylpentene-1, 4-methylhexene-1, 4,4-dimethylpentene-1, etc. Is mentioned. In addition, alpha-olefin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of α-olefin to ethylene is usually 2% by weight or more, preferably 5% by weight or more, more preferably 10% by weight or more, and usually 60% by weight or less, preferably 50% by weight or less. More preferably 30 wt% or less, ethylene is usually 40 wt% or more, preferably 50 wt% or more, more preferably 70 wt% or more, and usually 98 wt% or less, preferably 95 wt% or less, more preferably It is desirable that the content be 90% by weight or less.

  The blending ratio (component A / component B) of component A and component B is usually 50/50 or more, preferably 55/45 or more, more preferably 60/40 or more, and usually 99 / 1 or less, preferably 90/10 or less, more preferably 85/15 or less. Increasing the amount of component B tends to increase transparency and heat sealability, and decreasing the amount of component B tends to increase the workability of the film.

  The melt flow rate (MFR) of the resin composition for a sealing material produced by blending component A and component B is usually 2 g / 10 minutes or more, preferably 3 g / 10 minutes or more, and usually 50 g / 10 minutes. Hereinafter, it is preferably 40 g / 10 min or less. In addition, the measurement and evaluation of MFR can be implemented by the method based on JISK7210 (190 degreeC, 2.16kg load).

The melting point of the encapsulant resin composition is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, and is usually 300 ° C. or lower, preferably 250 ° C. or lower, more preferably 200 ° C. or lower. By increasing the melting point, the possibility of melting and deterioration during use of the solar cell module can be reduced.
The density of the encapsulating resin composition is preferably 0.80 g / cm ³ or more, more preferably 0.85 g / cm ³ or more, and preferably 0.98 g / cm ³ or less, 0.95 g / cm ^3. The following is more preferable, and 0.94 g / cm ³ or less is more preferable. The measurement and evaluation of density can be performed by a method based on JIS K7112.

Further, in the sealing material using the ethylene / α-olefin copolymer, a coupling agent can be used in the same manner as in the case of using the propylene / ethylene / α-olefin copolymer.
Since the sealing material described above does not generate a decomposition gas derived from the material, it does not adversely affect the photoelectric conversion layer, and has good heat resistance, mechanical strength, flexibility (solar cell sealing property) and transparency. Have. In addition, since a material cross-linking step is not required, the manufacturing time of the sheet molding and the solar cell module can be greatly shortened, and the solar cell module after use can be easily recycled.

Note that the sealing material layer may be formed of one kind of material or two or more kinds of materials. Moreover, although the sealing material may be formed with the single layer film, the laminated | multilayer film provided with the film of two or more layers may be sufficient as it.
In the present invention, as described above, ethylene-vinyl acetate copolymer, copolymer made of propylene / ethylene / α-olefin copolymer, copolymer made of ethylene / α-olefin copolymer are used as the material of the sealing material. Although coalescence was illustrated preferably, the effect of this invention can be acquired more by using these as a material of a sealing material.

Although there is no restriction | limiting in the position which provides a sealing material layer, Usually, it provides so that a photoelectric converting layer may be inserted | pinched. This is for reliably protecting the photoelectric conversion layer. In this embodiment, sealing materials are provided on the front surface and the back surface of the photoelectric conversion layer, respectively.
The thickness of the sealing material layer is not particularly limited, but is preferably 50 μm or more, more preferably 100 μm or more, further preferably 150 μm or more, and preferably 2000 μm or less, more preferably 1000 μm or less, and still more preferably 800 μm. It is as follows.

By increasing the thickness, mechanical strength tends to increase, and insulation between the photoelectric conversion layer and the substrate can be secured. Thinning tends to increase flexibility and increase light transmittance.
The solar cell module according to the present invention is lightweight and excellent in rigidity, but since a plurality of layers having different linear expansion coefficients are formed in combination, the role of the sealing material that connects them is important. From the viewpoint of making it difficult to transmit the thermal deformation stress of the surface protective layer and the back surface protective layer to the photoelectric conversion layer and the reinforcing layer, the sealing material preferably has a low elastic modulus. Preferably, the elastic modulus at 25 ° C. is preferably 100 MPa or less, more preferably 50 MPa or less, and most preferably 20 MPa or less. However, from the viewpoint of maintaining the sealing performance, the lower limit is preferably 0.01 MPa or more, more preferably 0.1 MPa or more, and most preferably 1 MPa or more. The elastic modulus of the sealing material can be measured by using a known dynamic viscoelasticity measuring method, but JIS K-7244 is preferable.

  For example, preferable specific examples for use in the present invention include a thermosetting EVA sealing material manufactured by CI Kasei Co., Ltd., a thermoplastic EVA sealing material manufactured by Koshin Rubber Co., Ltd., Dai Nippon Printing Co., Ltd. Examples thereof include a modified polyolefin sealing material manufactured by Mitsubishi, and a modified polyolefin sealing material manufactured by Mitsubishi Plastics (Proceria).

<Method for manufacturing solar cell module>
A known method can be used as the method for producing the solar cell module of the present invention. For example, a laminated body in which a multilayer sheet including a surface protective layer, a reinforcing layer, a photoelectric conversion layer, a back surface protective layer, and a sealing material is laminated is vacuumed. A solar cell module can be obtained by placing in a lamination device, heating after vacuuming, and cooling after a predetermined time.

The heat laminating conditions are not particularly limited, and heat laminating is possible under normal conditions.
It is preferably performed under vacuum conditions, and the degree of vacuum is usually 1 Pa or more, preferably 10 Pa or more, more preferably 30 Pa or more. On the other hand, the upper limit is usually 200 Pa or less, preferably 150 Pa or less, more preferably 100 Pa or less. By setting it as the said range, since generation | occurrence | production of a bubble can be suppressed in each layer in a module and productivity is also improved, it is preferable.

  Although it does not specifically limit as vacuum time, Usually, it is 1 minute or more, Preferably it is 2 minutes or more, More preferably, it is 3 minutes or more. On the other hand, the upper limit is usually 30 minutes or less, preferably 20 minutes or less, more preferably 10 minutes or less. Setting the vacuum time in the above range is preferable because the appearance of the solar cell module after heat lamination becomes good and the generation of bubbles in each layer in the module can be suppressed.

  The pressure condition of the heat laminate is not particularly limited, but the normal pressure is 50 kPa or more, preferably 70 kPa or more, more preferably 90 kPa or more. On the other hand, the upper limit value is 200 kPa or less, preferably 110 kPa or less. By setting it as the pressurization conditions of the said range, since moderate adhesiveness can be acquired, without damaging a solar cell module, it is preferable also from a durable viewpoint.

The pressure holding time is not particularly limited, but is usually 1 minute or longer, preferably 3 minutes or longer, more preferably 5 minutes or longer. On the other hand, the upper limit is usually 120 minutes or less, preferably 900 minutes or less, more preferably 60 minutes or less. By setting the holding time, sufficient adhesive strength can be obtained.
The temperature condition of the heat laminate is not particularly limited, but is usually 100 ° C. or higher, preferably 110 ° C. or higher, more preferably 120 ° C. or higher. On the other hand, the upper limit is usually 180 ° C. or lower, preferably 160 ° C. or lower, more preferably 150 ° C. or lower. By setting the temperature range, sufficient adhesive strength can be obtained.

Moreover, the heating time of the said temperature is although it does not specifically limit, Usually, 5 minutes or more, Preferably it is 10 minutes or more, More preferably, it is 15 minutes or more. On the other hand, the upper limit is 100 minutes or less, preferably 60 minutes or less, more preferably 45 minutes or less. By setting it as the said heating time, since durability of a sealing material is bridge | crosslinked moderately and it can have moderate softness | flexibility, it is preferable.
The solar cell module of the present invention can be installed and used in various places for various applications. In particular, it is preferably used as a solar cell module for a vehicle installed in a vehicle such as a passenger car, a truck, a bus, or a train.

  The solar cell module according to the present invention is lightweight and excellent in rigidity, but since a plurality of layers having different linear expansion coefficients are formed in combination, the thickness of the sealing material connecting them is important. Especially, at the periphery of the solar cell module where the stress generated inside the module due to the difference in thermal shrinkage between layers tends to concentrate, the sealing layer with excellent flexibility is made thick enough to concentrate the internal stress at the edge. It is important to avoid the occurrence of peeling from the peripheral edge of the solar cell module. The peripheral portion of the solar cell module described in the present invention is provided to protect the photoelectric conversion layer from moisture, oxygen, and the like from the end portion, and mainly on the periphery of the solar cell module, the surface protective layer, the back surface protective layer, A non-power generation region including a reinforcing layer and a sealing layer and not including a photoelectric conversion layer is provided.

The peripheral edge of the solar cell module is usually 5 mm or more and 200 mm or less, preferably 10 mm or more and 100 mm or less, in the direction from the arbitrary end face of the module to the center of the module (however, the center indicates the center of gravity of the solar cell module). Preferably they are 15 mm or more and 75 mm or less, Most preferably, they are 20 mm or more and 50 mm or less. If the thickness is less than 5 mm, the function of protecting the photoelectric conversion layer is significantly deteriorated. If it exceeds 200 mm, the module conversion efficiency is significantly reduced.

In the present invention, the thickness of the peripheral portion of the solar cell module is the thickness measured at the peripheral portion, but the thickness of the solar cell module at a position 3 mm inside from the arbitrary end face of the solar cell module toward the center. Of these, the smallest one is inserted.
The central portion of the solar cell module described in the present invention refers to a region including the photoelectric conversion layer, and the thickness is the thickness of the solar cell module at a position 300 mm inside from an arbitrary end surface of the module toward the center. Of these, the smallest one is inserted. However, when the distance to the center of the solar cell module is less than 300 mm from the end face, the thickness at the center is changed. These values can be measured by a known method. For example, a sheet gauge having a measurement depth of about 300 to 690 mm and a maximum measurement thickness of 20 to 50 mm can be used. It is also possible to measure with a contact type three-dimensional dimension measuring instrument.

  In the solar cell module of this invention, the thickness in the peripheral part of a solar cell module needs to be 80% or more of the thickness in the center part of a solar cell module. The thickness at the peripheral edge of the solar cell module is preferably 90% or more, and more preferably 95% or more. If this thickness is less than 80%, internal peeling at the end of the module tends to occur, which is not preferable. On the other hand, the thickness at the peripheral edge of the solar cell module is 120% or less, preferably 110% or less, more preferably 105% or less of the thickness at the center of the solar cell module. If it exceeds 120%, internal peeling tends to occur at the center of the module if it exceeds 120%.

  By the way, in the solar cell module of this invention, although the thickness in the peripheral part of a solar cell module needs to be 80% or more of the thickness in the center part of a solar cell module, a photoelectric conversion layer, depending on the case The thickness of the encapsulant layer at the peripheral part is more than the central part in order to align the peripheral part of the solar cell module that does not include the reinforcing layer to the same thickness as the central part and to suppress end peeling. Is preferably large. It is sufficient that the correlation between the thickness of the peripheral portion and the central portion of the solar cell module is adjusted to the above range, and the thickness of the sealing material is determined from the measured module thickness to a layer other than the sealing material. The original thickness (* in this case, the average value or the median value is adopted) can be easily calculated.

In the solar cell module of the present invention, the thickness at the peripheral portion of the solar cell module is 80% or more of the thickness at the central portion of the solar cell module, and / or the sealing material layer at the peripheral portion rather than the central portion. In order to increase the thickness, when using a vacuum laminator in the form of a diaphragm sheet that is flat on the bottom and flexible on the top, it is necessary to prevent compressive stress from concentrating on the end of the module during thermal lamination. is necessary. The specific method is not particularly limited. For example, the module is surrounded by a bar (made of metal or heat-resistant resin) having a width of about 10 to 50 mm and substantially the same thickness as the peripheral edge of the module. For example, a high-rigid metal plate can be used. Further, if a vacuum laminator of a type in which the upper and lower sides are flat hot plates is used, it is easy to avoid application of pressure stress to the module end.

  Also, since there is no photoelectric conversion layer in the module periphery, and in some cases no reinforcing layer, there is a tendency to make a difference with the thickness of the center, so only the periphery is sealed to a thickness that compensates for the difference. Adding a material layer is also highly effective. By doing in this way, the thickness of the sealing material in the central portion is also difficult to reduce, and the thickness of the peripheral portion is also unlikely to be insufficient.

<Example 1>
The solar cell module 1 was manufactured according to the following procedure.
Specifically, the back protective layer has a length of 890 mm and a width of 680 mm, on a polycarbonate sheet of 1.5 mm thickness (manufactured by Takiron Co., Ltd.), a size of 890 mm in length and 680 cm in width, and a thickness of 0 .4 mm sealing layer (C-I Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) was placed, and as a reinforcing layer, the same size as this sealing layer, with a thickness of 0.1 mm A PET film (Mitsubishi Resin Co., Ltd., model: E680E100) is placed, and a sealing layer having the same size as the reinforcing layer and a thickness of 0.4 mm (Ci Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA)) Sheet). On top of that, as a photoelectric conversion layer, four 6-inch single crystal silicon cells (manufactured by Shinsung, SH-1990S3), which are connected by three interconnectors with a gap of 4 mm, are arranged in parallel at intervals of 4 mm. These were placed electrically connected in series using a solder-coated copper wire having a width of 5 mm and a thickness of 0.18 mm. And on this photoelectric conversion layer, a size is 890 mm in length, 680 cm in width, and a thickness of 0.4 mm (Sea Chemical Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet). As a reinforcing layer, a PET film (Mitsubishi Resin Co., Ltd., model: E680E100) having the same size as the sealing layer and a thickness of 0.1 mm is placed, and the reinforcing layer has the same size as the reinforcing layer and a thickness of 0. A 4 mm sealing layer (produced by C-I Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is stacked, and the surface protective layer has a size of 890 mm in length, 680 mm in width, and 1.5 mm in thickness. A polycarbonate sheet (manufactured by Takiron Co., Ltd.) was placed on the laminate. At this time, an aluminum spacer having the same height as the module peripheral portion thickness is arranged as shown in FIG. 2 so that atmospheric pressure does not concentrate on the peripheral portion of the module, and a solar cell module laminator (NLM-270, manufactured by NPC) × 400). First, the inside of the laminator was held for 10 minutes under reduced pressure, and then the laminate was held at 130 ° C. for 60 minutes while being brought into a pressure-bonded state at atmospheric pressure to obtain the solar cell module 1 shown in FIG.

  About the total thickness of the solar cell module 1, the thickness of a center part and a peripheral part was measured. Moreover, the total thickness of the sealing layer contained in a solar cell module was each measured in the peripheral part and the center part. It put into the temperature cycle test (8 hours / cycle) of -40 degreeC-+80 degreeC. Table 1 shows the results of confirming the presence or absence of internal peeling after 10 cycles.

<Example 2>
The solar cell module 2 was created by the following procedure.
Specifically, as a back surface protective layer, the size is 890 mm in length and 680 mm in width, and a 1.8 mm thick polycarbonate sheet (manufactured by Ryojo Techno Co., Ltd., an acrylic film having a thickness of 0.07 mm is heated on one side of the polycarbonate sheet. A sealing layer of the same size and a thickness of 0.5 mm (made by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (with the acrylic film surface on the non-light-receiving surface side)) EVA) sheet) and a PET sheet (Mitsubishi Resin Co., Ltd., model: T103E188) having the same size as this sealing layer and a thickness of 0.188 mm as the reinforcing layer, and the same as the reinforcing layer A sealing layer having a size and a thickness of 0.3 mm (manufactured by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) was stacked. On top of that, as a photoelectric conversion layer, four 6-inch single crystal silicon cells (manufactured by Shinsung, SH-1990S3), which are connected by three interconnectors with a gap of 4 mm, are arranged in parallel at intervals of 4 mm. These were placed electrically connected in series using a solder-coated copper wire having a width of 5 mm and a thickness of 0.18 mm. On this photoelectric conversion layer, a sealing layer having the same size and a thickness of 0.3 mm (produced by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is placed, and the reinforcing layer The same size as this sealing layer and a 0.188 mm thick PET film (Mitsubishi Resin Co., Ltd., model: E680E100) are placed, and the same size and 0.5 mm thick sealing layer (Cai Kasei) Co., Ltd., an ethylene-vinyl acetate copolymer (EVA) sheet) are stacked, and the surface protective layer is the same size and 1.8 mm thick polycarbonate sheet (manufactured by Ryojo Techno Co., Ltd., 0.07 mm thick acrylic sheet). A film was heat-sealed to one side of a polycarbonate sheet. The acrylic film side was the light-receiving side. At this time, a Teflon (registered trademark) spacer having a height substantially equal to the module peripheral portion thickness is arranged as shown in FIG. 4 so that the atmospheric pressure does not concentrate on the peripheral portion of the module, and a solar cell module laminator (manufactured by NPC) , NLM-270 × 400). First, the interior of the laminator was held under reduced pressure for 10 minutes, and then the laminate was held in a pressure-bonded state at atmospheric pressure for 60 minutes at 130 ° C. to obtain a solar cell module 2 shown in FIG. About the total thickness of the solar cell module 2, the thickness of a center part and a peripheral part was measured. Moreover, the total thickness of the sealing layer contained in a solar cell module was each measured in the peripheral part and the center part. It put into the temperature cycle test (8 hours / cycle) of -40 degreeC-+80 degreeC. Table 1 shows the results of confirming the presence or absence of internal peeling after 10 cycles.

<Example 3>
The solar cell module 3 was created by the following procedure.
Specifically, as a back surface protective layer, the size is 890 mm in length and 680 mm in width, and a 1.8 mm thick polycarbonate sheet (manufactured by Ryojo Techno Co., Ltd., an acrylic film having a thickness of 0.07 mm is heated on one side of the polycarbonate sheet. A sealing layer of the same size and a thickness of 0.5 mm (made by CI Kasei Co., Ltd., fast-curing type ethylene-vinyl acetate) A polymer (EVA) sheet) is placed, and as a reinforcing layer, a PET sheet (Mitsubishi Resin Co., Ltd., model: T103E188) having the same size as this sealing layer and a thickness of 0.188 mm is placed and reinforced. A sealing layer having the same size as the layer and having a thickness of 0.3 mm (produced by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) was stacked. On top of that, as a photoelectric conversion layer, four 6-inch single crystal silicon cells (manufactured by Shinsung, SH-1990S3), which are connected by three interconnectors with a gap of 4 mm, are arranged in parallel at intervals of 4 mm. These were placed electrically connected in series using a solder-coated copper wire having a width of 5 mm and a thickness of 0.18 mm. On this photoelectric conversion layer, a sealing layer having the same size and a thickness of 0.3 mm (produced by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is placed, and the reinforcing layer As a result, a glass plate (manufactured by Asahi Glass Co., Ltd.) having a size of 850 mm long × 640 mm wide and a thickness of 0.4 mm was placed. On top of that, a sealing layer having the same size as that of the back surface protective layer and having a thickness of 0.3 mm (produced by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is stacked, and further on the back surface As a reinforcing layer having the same size as the protective layer, a 0.188 mm thick PET sheet (Mitsubishi Resin Co., Ltd., model: T103E188) is placed, and the sealing layer having the same size as this reinforcing layer and a thickness of 0.3 mm (Chi-Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is overlaid, and a polycarbonate sheet (rhizome) having the same size as the back surface protective layer and a thickness of 1.8 mm as the surface protective layer thereon. A product made by Sakai Techno Co., Ltd., having an acrylic film with a thickness of 0.07 mm heat-sealed on one side of a polycarbonate sheet. The acrylic film side was the light-receiving surface side.

Before putting this laminate into the laminator, the size of the back surface protection layer and the glass plate are different, so an EVA sheet (Ci Kasei Co., Ltd.) with a thickness of 0.5 mm is uniformly distributed around the glass plate. The area (gap) where there was no glass plate was filled (8 EVA sheet in FIG. 5). At this time, in order to prevent atmospheric pressure from concentrating on the peripheral edge of the module, as in Example 1, this laminated body was placed in a solar cell module laminator (NPC) with an aluminum spacer having a height substantially the same as the thickness of the peripheral edge of the module. NLM-270 × 400). First, the inside of the laminator was held for 10 minutes under reduced pressure, and then the laminate was held in a pressure-bonded state at atmospheric pressure for 60 minutes to obtain a solar cell module 3 shown in FIG. About the total thickness of the solar cell module 3, the thickness of a center part and a peripheral part was measured. Moreover, the total thickness of the sealing layer contained in a solar cell module was each measured in the peripheral part and the center part. It put into the temperature cycle test (8 hours / cycle) of -40 degreeC-+80 degreeC. Table 1 shows the results of confirming the presence or absence of internal peeling after 10 cycles.

<Example 4>
The solar cell module 4 was created by the following procedure.
Specifically, as the back surface protective layer, the size is 400 mm in length and 200 mm in width, and a polycarbonate plate with a hard coat having a thickness of 1.8 mm (one surface of “Stella” is hard-coated. A non-light-receiving surface), and a sealing layer of the same size and a thickness of 0.3 mm (CAI Kasei Co., Ltd., fast-curing type ethylene-vinyl acetate copolymer (EVA) sheet) Further, a polyolefin encapsulant sheet (Dai Nippon Printing Co., Ltd., Z74) having the same size and thickness of 0.4 mm was stacked.

  On top of that, two 6-inch single crystal silicon cells (manufactured by Shinsung, SH-1990S3), which are connected by three interconnectors with a gap of 4 mm, were placed as a photoelectric conversion layer. And on this photoelectric conversion layer, the same size as the back surface protective layer, and a sealing layer having a thickness of 0.3 mm (manufactured by C-I Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is placed, Then, as a reinforcing layer, a glass plate (manufactured by Asahi Glass Co., Ltd.) having a size of 360 mm × 160 mm and a thickness of 0.4 mm was placed. On top of that, a polyolefin-based sealing material sheet (Dai Nippon Printing Co., Ltd., Z74) having the same size as the back surface protective layer and a thickness of 0.4 mm and a sealing layer having a thickness of 0.3 mm (CI Chemical Co., Ltd.) Made of an ethylene-vinyl acetate copolymer (EVA) sheet), and a polycarbonate plate ("Stella") with the same size as the back surface protective layer and a 1.8mm thickness hard coat on it as the surface protective layer The surface was hard-coated. The hard-coated surface was used as the light-receiving surface.

  Before putting this laminate into the laminator, the size of the back surface protection layer and the glass plate are different, so an EVA sheet (Ci Kasei Co., Ltd.) with a thickness of 0.5 mm is uniformly distributed around the glass plate. The area (gap) where there was no glass plate was filled (EVA sheet 7 in FIG. 6). At this time, in order to prevent atmospheric pressure from concentrating on the peripheral edge of the module, as in Example 2, the laminated body was placed in a state where a Teflon (registered trademark) spacer having a height substantially equal to the thickness of the peripheral edge of the module was disposed. It put into the module laminator (the product made by NPC, NLM-270 * 400). First, the interior of the laminator was held under reduced pressure for 10 minutes, and then the laminate was held in a pressure-bonded state at atmospheric pressure for 60 minutes at 130 ° C. to obtain a solar cell module 4 shown in FIG. About the total thickness of the solar cell module 4, the thickness of a center part and a peripheral part was measured. Moreover, the total thickness of the sealing layer contained in a solar cell module was each measured in the peripheral part and the center part. It put into the temperature cycle test (8 hours / cycle) of -40 degreeC-+80 degreeC. Table 1 shows the results of confirming the presence or absence of internal peeling after 10 cycles.

<Comparative Example 1>
The solar cell module 5 was created by the following procedure.
Specifically, as a back surface protective layer, the size is 890 mm in length and 680 mm in width, and a 1.8 mm thick polycarbonate sheet (manufactured by Ryojo Techno Co., Ltd., an acrylic film having a thickness of 0.07 mm is heated on one side of the polycarbonate sheet. A sealing layer of the same size and a thickness of 0.5 mm (made by CI Kasei Co., Ltd., fast-curing type ethylene-vinyl acetate) A polymer (EVA) sheet) is placed, and as a reinforcing layer, a PET sheet (Mitsubishi Resin Co., Ltd., model: T103E188) having the same size as this sealing layer and a thickness of 0.188 mm is placed and reinforced. A sealing layer having the same size as the layer and having a thickness of 0.3 mm (produced by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) was stacked. On top of that, as a photoelectric conversion layer, four 6-inch single crystal silicon cells (manufactured by Shinsung, SH-1990S3), which are connected by three interconnectors with a gap of 4 mm, are arranged in parallel at intervals of 4 mm. These were placed electrically connected in series using a solder-coated copper wire having a width of 5 mm and a thickness of 0.18 mm. On this photoelectric conversion layer, a sealing layer having the same size and a thickness of 0.3 mm (produced by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is placed, and the reinforcing layer As a result, a glass plate (manufactured by Asahi Glass Co., Ltd.) having a size of 850 mm long × 640 mm wide and a thickness of 0.4 mm was placed. On top of that, a 0.5 mm-thick sealing layer having the same size as that of the back surface protective layer (produced by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is overlaid, and the surface protection is performed thereon. As a layer, a polycarbonate sheet having the same size as the back surface protective layer and a thickness of 1.8 mm (manufactured by Ryojo Techno Co., Ltd., and heat-sealing an acrylic film having a thickness of 0.07 mm on one side of the polycarbonate sheet. It was placed on the surface side.

And this laminated body was thrown into the solar cell module laminator (the product made by NPC, NLM-270 * 400). First, the inside of the laminator was held for 10 minutes under reduced pressure, and then the laminated body was held at 130 ° C. for 60 minutes while being brought into a pressure-bonded state at atmospheric pressure to obtain a solar cell module 5.
About the total thickness of the solar cell module 5, the thickness of a center part and a peripheral part was measured. Moreover, the total thickness of the sealing layer contained in a solar cell module was each measured in the peripheral part and the center part. It put into the temperature cycle test (8 hours / cycle) of -40 degreeC-+80 degreeC. Table 1 shows the results of confirming the presence or absence of internal peeling after 10 cycles.

<Comparative example 2>
The solar cell module 6 was created by the following procedure.
Specifically, as the back surface protective layer, the size is 890 mm long and 680 mm wide, and the same size and 0.5 mm thick seal on a 2.0 mm thick polycarbonate sheet (manufactured by Takiron). A glass plate having the same size as this sealing layer and a thickness of 0.4 mm as a reinforcement layer (layer made by C-I Kasei Co., Ltd., fast-curing type ethylene-vinyl acetate copolymer (EVA) sheet) (Asahi Glass Co., Ltd.) was placed. On top of this, as the sealing layer, a sealing layer having the same size as the back surface protective layer and having a thickness of 0.3 mm (produced by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is overlaid. On top of that, as a photoelectric conversion layer, four 6-inch single crystal silicon cells (manufactured by Shinsung, SH-1990S3) connected by three interconnectors with a gap of 4 mm are arranged in parallel at intervals of 4 mm. These were placed electrically connected in series using a solder-coated copper wire having a width of 5 mm and a thickness of 0.18 mm.

  On this photoelectric conversion layer, a sealing layer having the same size and a thickness of 0.3 mm (produced by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is placed, and the reinforcing layer As a result, a glass plate (manufactured by Asahi Glass Co., Ltd.) having a size of 850 mm long × 640 mm wide and a thickness of 0.4 mm was placed. On top of that, a 0.5 mm-thick sealing layer having the same size as that of the back surface protective layer (produced by CI Kasei Co., Ltd., ethylene-vinyl acetate copolymer (EVA) sheet) is overlaid, and the surface protection is performed thereon. As a layer, a polycarbonate sheet (manufactured by Takiron Co., Ltd.) having the same size as the back surface protective layer and a thickness of 2.0 mm was placed to obtain a laminate. And this laminated body was thrown into the solar cell module laminator (the product made by NPC, NLM-270 * 400). First, the inside of the laminator was held under reduced pressure for 10 minutes, and then the laminated body was held at 130 ° C. for 60 minutes while being brought into a pressure-bonded state at atmospheric pressure to obtain a solar cell module 6.

  About the total thickness of the solar cell module 6, the thickness of a center part and a peripheral part was measured. Moreover, the total thickness of the sealing layer contained in a solar cell module was each measured in the peripheral part and the center part. It put into the temperature cycle test (8 hours / cycle) of -40 degreeC-+80 degreeC. Table 1 shows the results of confirming the presence or absence of internal peeling after 10 cycles.

<Comparative Example 3>
In Example 1, except that the laminator was carried out without using a mold spacer, a laminate was similarly formed to obtain a solar cell module 7.
About the total thickness of the solar cell module 7, the thickness of a center part and a peripheral part was measured. Moreover, the total thickness of the sealing layer contained in a solar cell module was each measured in the peripheral part and the center part. It put into the temperature cycle test (8 hours / cycle) of -40 degreeC-+80 degreeC. Table 1 shows the results of confirming the presence or absence of internal peeling after 10 cycles.

1 Surface protective layer
2 Back side protective layer
3 Photoelectric conversion layer
31 Electric wire (interconnector)
4 Sealing layer
5 Reinforcement layer (PET)
6 Spacer (mold)
7 Reinforcing layer (PET)
8 Reinforcing layer (glass)
9 EVA sheet
10 Sealing layer (polyolefin resin)
11 Surface protective layer (with acrylic sheet)
12 Surface protective layer (with surface hard coat)
21 Back side protective layer (with acrylic sheet)
22 Surface protective layer (with hard surface coating)

Claims (5)

  A solar cell module in which a photoelectric conversion layer and a reinforcing layer are sealed with a sealing material between a surface protective layer and a back surface protective layer containing a resin having a Young's modulus at 23 ° C. of 1 GPa or more and 5 GPa or less, The linear expansion coefficient of the back surface protective layer at 30 ° C. is 20 ppm / K or more larger than the linear expansion coefficient of the reinforcing layer at 0 to 30 ° C. and / or the linear expansion coefficient of the surface protective layer at 0 to 30 ° C. is 0. It is larger than the linear expansion coefficient of the reinforcing layer at -30 ° C by 20 ppm / K or more, and the thickness at the peripheral portion of the solar cell module is 80% or more of the thickness at the central portion of the solar cell module. Solar cell module.   2. The solar cell module according to claim 1, wherein an area of the laminated surface of the reinforcing layer is smaller than an area of the laminated surface of the back surface protective layer and / or the surface protective layer and is equal to or larger than the area of the photoelectric conversion layer.   3. The solar cell module according to claim 1, wherein a thickness of a sealing layer included in the solar cell module formed by the sealing material is larger at a peripheral portion than at a central portion.   Two or more reinforcing layers are included, at least one of the reinforcing layers is between the back surface protective layer and the photoelectric conversion layer, and at least one of the reinforcing layers is the surface protective layer and the photoelectric conversion layer. The solar cell module according to claim 1, wherein the solar cell module is between.   The solar cell module according to any one of claims 1 to 4, wherein a thickness of the entire peripheral portion of the solar cell module is 5 mm or more.