JP2018050027A - Solar cell module - Google Patents

Abstract

In a solar cell module of a double-sided glass protection substrate type, while maintaining sufficient heat resistance, by sufficiently suppressing “cell cracking” and “cell deviation” during lamination, the quality of the conventional product is improved. Provided is a double-sided glass protective substrate type solar cell module having excellent stability. A double-sided glass protective substrate type solar cell module, wherein a light-receiving surface side sealing material 2 is made of a polyethylene resin having a density of 0.900 g / cm 3 or less as a base resin, and has a gel fraction of 20% or more. 80% or less, the non-light-receiving surface side sealing material 3 is made of a polyethylene resin having a base fraction of 0.870 g / cm 3 or more and 0.930 g / cm 3 or less, and has a gel fraction of 0%. module. [Selection] Figure 1

Description

  The present invention relates to a solar cell module. More specifically, the present invention relates to a double-sided glass protective substrate type solar cell module.

  In recent years, solar cells as a clean energy source have attracted attention due to the growing awareness of environmental issues. Currently, various types of solar cell modules have been developed. Generally, a solar cell module has a configuration in which a transparent front protective substrate, a solar cell element, and a resin back protective substrate are laminated via a sealing material.

  There are various layers of solar cell modules, and the above-mentioned front protective substrate and the above-mentioned protective layer are particularly excellent in terms of barrier properties to prevent moisture from entering the module and long-term durability under severe use conditions. A solar cell module has been devised in which the back surface protection substrate is made of a glass protection substrate (see Patent Documents 1 and 2). In this specification, a solar cell module having a configuration in which the protective substrates disposed on both outermost surfaces of the module main body are glass substrates is referred to as a “double-sided glass protective substrate type solar cell module”.

  Here, the solar cell module is obtained by integrating the solar electronic element and the module constituent member including the sealing material and the like by a laminating process involving heating and pressing, regardless of the configuration. Manufactured. At the time of heat and pressure treatment for integration as a module, if the fluidity of the sealing material is insufficient, the follow-up to unevenness such as solar cell elements and lead wires and the embedding property (molding property) are lacking. When the risk of solar cell element damage (cell cracking) increases, while excessive fluidity, the solar cell element installed in the solar cell module is unnecessarily moved from the installation position during the lamination process. There was a problem of causing misalignment (cell misalignment).

  The phenomenon of “cell cracking” and “cell misalignment” due to insufficient or excessive fluidity as described above is a problem in the production of a double-sided glass protective substrate type solar cell module that is likely to be subjected to high pressure and tension by the sealing material during the laminating process. In particular, an improvement means for avoiding these phenomena has been desired which is easily manifested.

JP 11-31834 A JP 2013-98306 A

  The present invention has been made in view of the above situation, and in a double-sided glass protective substrate type solar cell module excellent in durability and barrier properties, while maintaining sufficient heat resistance, “cell cracking at the time of lamination” It is an object of the present invention to provide a solar cell module of a double-sided glass protective substrate type that is superior in stability of quality as compared with conventional products by sufficiently suppressing the “cell displacement” and “cell displacement”.

  As a result of intensive studies, the inventors of the present invention have made a double-sided glass protective substrate type solar cell module in which only a sealing material disposed on the light-receiving surface side of the solar cell element is sufficiently crosslinked. The present inventors have found that the above problems can be solved by using a sealing material, and have completed the present invention. More specifically, the present invention provides the following.

(1) A double-sided glass protective substrate type solar in which a light-receiving surface side glass protective substrate, a light-receiving surface side sealing material, a solar cell element, a non-light-receiving surface side sealing material, and a non-light-receiving surface side glass protective substrate are sequentially laminated. In the battery module, the light-receiving surface side sealing material is made of a polyethylene resin having a density of 0.900 g / cm ³ or less as a base resin, and has a gel fraction of 20% to 80%. surface-side sealing member is made as a 0.870 g / cm ³ or more 0.930 g / cm ³ or less polyethylene resin as a base resin of the gel fraction is 0%, the solar cell module.

(2) The non-light-receiving surface side sealing material is a multilayer sealing material constituted by a plurality of layers including a core layer and a skin layer disposed on both outermost surfaces, becomes a density of 0.910 g / cm ³ or more 0.930 g / cm ³ or less polyethylene resin as a base resin of the skin layer based on density 0.890 g / cm ³ or more 0.910 g / cm ³ or less of the polyethylene resin The solar cell module according to (1), which is made of resin.

  (3) In the non-light-receiving surface side sealing material, the core layer has a thickness of 100 μm or more and 600 μm or less, the melting point of the core layer is 90 ° C. or more and 135 ° C. or less, and the thickness of each layer of the skin layer The solar cell module according to (1) or (2), wherein each has a melting point of 55 ° C. or more and 100 ° C. or less.

(4) the non-light-receiving side encapsulant becomes a density 0.870 g / cm ³ or more 0.900 g / cm ³ or less of the polyethylene resin as the base resin, is substantially free of cross-linking aid, JIS The solar cell module according to (1), which is a sealing material having an MFR measured in accordance with K7210 at 190 ° C. and a load of 2.16 kg of 0.1 g / 10 min to 1.0 g / 10 min.

  (5) The light-receiving surface side sealing material and the non-light-receiving surface side sealing material contain a silane copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer (1 The solar cell module according to any one of (4) to (4).

  (6) The non-light-receiving surface side sealing material is a multilayer white sealing material configured by a plurality of layers including a white core layer and a skin layer disposed on the outermost surface, and the white core The solar cell module according to any one of (1) to (5), wherein a white coloring material is included only in the layer.

  (7) The solar cell module according to (6), wherein polypropylene is contained in the white core layer in an amount of 5% by mass to 40% by mass with respect to all resin components of the white core layer.

  (8) The polypropylene contained in the white core layer is a homopolypropylene having an MFR of 5 g / 10 min to 125 g / 10 min at 230 ° C. and a load of 2.16 kg measured according to JIS K7210 (7 ) Solar cell module.

  (9) A non-light-receiving surface side white sealing material is further laminated between the non-light-receiving surface side sealing material and the non-light-receiving surface side glass protective substrate, and the non-light-receiving surface side white sealing material Is a multi-layer sealing material composed of a plurality of layers including a white core layer and a skin layer disposed on the outermost surface, and only the white core layer contains a white coloring material The solar cell module according to any one of (1) to (5).

(10) A method for producing a solar cell module of a double-sided glass protective substrate type according to any one of (1) to (9), wherein a low-density polyethylene having a density of 0.900 g / cm ³ or less, a crosslinking agent, The light-receiving surface is obtained by subjecting an uncrosslinked sealing material formed by forming a sealing material composition containing a crosslinking aid to a gel fraction of 20% to 80%. A method for manufacturing a solar cell module, comprising a step of obtaining a side glass protective substrate, wherein the non-light-receiving surface side sealing material is not subjected to crosslinking treatment after film formation.

  According to the present invention, it was made in view of the above situation, and in a double-sided glass protective substrate type solar cell module excellent in durability and barrier properties, while maintaining sufficient heat resistance, “ By sufficiently suppressing “cell cracking” and “cell displacement”, it is possible to provide a solar cell module of a double-sided glass protective substrate type that is superior in stability of quality compared to conventional products.

It is drawing which shows typically the laminated constitution of the solar cell module of a double-sided glass protective substrate type | mold of this invention. It is drawing which shows typically the layer structure of the light-receiving surface side sealing material which comprises the solar cell module of the double-sided glass protection substrate type | mold of this invention. It is drawing which shows typically the layer structure of the non-light-receiving surface side sealing material which comprises the solar cell module of a double-sided glass protection substrate type | mold of this invention. It is drawing which shows typically the layer structure of the non-light-receiving surface side white sealing material which comprises the solar cell module of a double-sided glass protection substrate type | mold of this invention.

  Hereinafter, the solar cell module of the present invention and the sealing material used for the solar cell module will be sequentially described.

<Solar cell module>
FIG. 1: is sectional drawing which shows an example of the laminated constitution about the solar cell module 10 of the double-sided glass protection substrate type | mold of this invention. The solar cell module 10 includes, from the light receiving surface side of incident light, the light receiving surface side glass protective substrate 1, the light receiving surface side sealing material 2, the non-light receiving surface side sealing material 3, the non-light receiving surface side white sealing material 4, and the non-light receiving surface side sealing material 2. The light-receiving surface side glass protective substrate 5 is laminated in this order, and the solar cell element 6 is disposed in such a manner that the light-receiving surface side sealing material 2 and the non-light-receiving surface side sealing material 3 are sealed. In addition, about the non-light-receiving surface side white sealing material 4, although it is not an essential structural requirement in the solar cell module of this invention, it is between the non-light-receiving surface side sealing material 3 and the non-light-receiving surface side glass protective substrate 5. By arranging this, the power generation efficiency of the solar cell module can be further improved.

  In the solar cell module 10, the light receiving surface side in which the heat resistance is sufficiently improved by using a low density polyethylene excellent in fluidity on the light receiving surface side of the solar cell element and sufficiently crosslinking the module when it is modularized. Sealing material 2 is arranged. In the present specification, a sealing material that is formed as a non-cross-linked film on the premise that cross-linking proceeds in the process after film formation is referred to as a “cross-linking type sealing material”, and at least A sealing material that is not premised on the progress of crosslinking in the process after film formation is referred to as a “thermoplastic sealing material” or a “non-crosslinking sealing material”.

  On the other hand, on the non-light-receiving surface side of the solar cell module 10, a thermoplastic (non-crosslinked) non-light-receiving surface side sealing material 3 and, if necessary, a non-light-receiving surface side white sealing material 4 are arranged. Has been.

  In the solar cell module 10, when the non-light-receiving surface side white sealing material 4 is arranged as described above, out of the incident light from the light-receiving surface side, the light does not enter the solar cell element 6 and is on the non-light-receiving surface side. The sunlight that has reached is reflected at the interface between the non-light-receiving surface side sealing material 3 and the non-light-receiving surface side white sealing material 4 and is guided again to the light-receiving surface side of the solar cell element 6. The power generation efficiency of the battery module 10 is improved.

  Further, in the solar cell module 10, the non-light-receiving surface side white sealing as described above can also be achieved by adding a white coloring material to the non-light-receiving surface side sealing material 3 and using this as a white sealing material. The same power generation efficiency improvement effect as that of the configuration in which the material 4 is arranged can be enjoyed with a simpler configuration. Details of each of these sealing materials will be described later.

  About the light-receiving surface side glass protective substrate 1 and the non-light-receiving surface side glass protective substrate 5, various glass plate materials conventionally used as a light-transmitting substrate material constituting the solar cell module can be used without particular limitation. it can. In addition, the solar cell module 10 of this invention may also contain members other than the said member.

  The solar cell element 6 is not particularly limited. Not only a crystalline silicon solar cell manufactured using a single crystal silicon substrate or a polycrystalline silicon substrate, but also a thin film solar cell (CIGS) using amorphous silicon, microcrystalline silicon, a chalcopyrite compound, or the like is preferably used. be able to.

[Method for manufacturing solar cell module]
The solar cell module 10 includes the light receiving surface side glass protective substrate 1, the light receiving surface side sealing material 2, the non-light receiving surface side sealing material 3, the non-light receiving surface side glass protective substrate 5, the solar cell element 6 and the like. The module constituent members can be laminated one after another and integrated by vacuum suction or the like, and thereafter, the above members can be manufactured by thermocompression molding as an integral molded body by a molding method such as a lamination method.

  Among the sealing materials constituting the solar cell module 10, for the light-receiving surface side sealing material 2, a sealing material composition for the light-receiving surface side sealing material is formed as an uncrosslinked film, The step of crosslinking treatment so that the gel fraction is 20% or more and 80% or less is performed in the manufacturing process of the solar cell module. This crosslinking treatment can be performed by advancing a crosslinking reaction at the time of thermocompression bonding during lamination performed at the time of modularization. Alternatively, if necessary depending on the lamination conditions, a separate thermal crosslinking treatment may be performed after further modularization.

  On the other hand, the other sealing materials, that is, the non-light-receiving surface side sealing material 3 and the non-light-receiving surface side white sealing material 4 do not contain a crosslinking agent or do not substantially remain after film formation. Since the encapsulant composition is used, after the film formation, a crosslinking treatment in the manufacturing process of the solar cell module is unnecessary.

<Light-receiving surface side sealing material>
The light-receiving surface side sealing material 2 is formed of a crosslinked resin film having a density of 0.900 g / cm ³ or less as a base resin and a gel fraction of 20% to 90%.

  In this specification, “gel fraction (%)” means that 0.1 g of a sealing material is put into a resin mesh, extracted with toluene at 120 ° C. for 24 hours, taken out together with the resin mesh, weighed after drying, and before and after extraction. The mass ratio of the residual insoluble matter is measured and the gel fraction is obtained. The gel fraction of 0% means that the residual insoluble matter is substantially 0, and the crosslinking reaction of the sealing material composition has not substantially started. More specifically, “gel fraction 0%” means that the above-mentioned residual insoluble matter is not present at all, and that the above-mentioned residual insoluble matter mass% measured by a precision balance is less than 0.05% by mass. Shall be said. The residual insoluble matter does not include pigment components other than the resin component. When a mixture other than these resin components is mixed in the residual insoluble matter by the above test, for example, by separately measuring the content of these mixtures in the resin component beforehand, The gel fraction that should be originally obtained can be calculated for the residual insoluble matter derived from the resin component excluding the inclusions.

  The light-receiving surface side sealing material 2 is formed into a film or sheet by molding a sealing material composition for the light-receiving surface side sealing material having a composition specific to the present application by a conventionally known method. In addition, the sheet form in this invention means the film form, and there is no difference in both.

  The light-receiving surface side sealing material 2 may be a single-layer film, but as shown in FIG. 2, it is a multilayer film composed of a core layer 21 and skin layers 22 disposed on both surfaces of the core layer. Also good. The multilayer film in the present specification is a film or sheet having a structure having at least one outermost layer, preferably a skin layer formed on both outermost layers, and a core layer which is a layer other than the skin layer. Say that. When the light-receiving surface side sealing material 2 is a multi-layer film, the layers within the composition range of the sealing material composition for the light-receiving surface side sealing material described later and having different compositions and component ratios are used for each layer. Can do.

  For example, when the light-receiving surface side sealing material 2 is a multilayer film composed of three or more layers, the thickness of the skin layer 22 is preferably 30 μm or more and 200 μm or less, and the core layer 21 and the skin The thickness ratio of the layer 22 is preferably in the range of skin layer: core layer: skin layer = 1: 3: 1 to 1: 8: 1. By setting it as such layer thickness ratio, the preferable molding characteristic in the skin layer 22 can be provided, maintaining the preferable heat resistance as a light-receiving surface side sealing material.

  In the solar cell module 10, the light-receiving surface side sealing material 2 is made of low-density polyethylene having excellent fluidity as a base resin, and crosslinking is advanced so that the gel fraction becomes 20% or more and 90% or less when modularized. A feature of the layer structure is that it is a cross-linking encapsulant that can sufficiently improve heat resistance.

[Sealant composition for light-receiving surface side sealant]
The sealing material composition for the light-receiving surface-side sealing material used for manufacturing the light-receiving surface-side sealing material 2 is a cross-linked resin composition that uses a low-density polyethylene-based resin as a base resin and requires a crosslinking agent. is there.

The sealing material composition for the light receiving surface side sealing material has a density of 0.900 g / cm ³ or less, more preferably a polyethylene resin having a density of 0.870 g / cm ³ or more and 0.890 g / cm ³ or less as a base resin. To do. By using the low-density polyethylene resin as the base resin as described above, the adhesion between the light-receiving surface side sealing material 2 and the light-receiving surface side glass protective substrate 1 is increased, and when each member is pressed in the laminating process The risk of cell cracking can be reduced. Content of said base resin with respect to all the resin components in the sealing material composition for light-receiving surface side sealing materials is 50 to 99 mass%, Preferably it is 90 to 99 mass%. . As long as the base resin is included within the above range, the composition may contain another resin within a range that does not impair the effects of the present invention.

  The polyethylene resin used as the base resin of the sealing material composition for the light receiving surface side sealing material is low density polyethylene (LDPE), preferably linear low density polyethylene (LLDPE). The linear low density polyethylene is more preferably a copolymer of ethylene and α-olefin. The base resin is more preferably a metallocene linear low density polyethylene. Metallocene linear low density polyethylene is synthesized using a metallocene catalyst which is a single site catalyst. Such polyethylene has few side chain branches and a uniform comonomer distribution. For this reason, molecular weight distribution is narrow, it is possible to make it the above ultra-low density, and a softness | flexibility can be provided with respect to a sealing material. As a result of the flexibility imparted to the sealing material, the adhesion between the sealing material and glass, metal, or the like increases.

  In addition, linear low density polyethylene has a narrow crystallinity distribution and a uniform crystal size, so that not only a large crystal size does not exist, but also the crystallinity itself is low because of its low density. For this reason, it is excellent in transparency when processed into a sheet shape as a sealing material. Therefore, the incident in the case where the sealing material made of the sealing material composition for the light receiving surface side sealing material using this as a base resin is disposed between the light receiving surface side glass protective substrate 1 and the solar cell element 6. A decrease in power generation efficiency due to light attenuation can be prevented.

  The melt mass flow rate (MFR) of the above polyethylene-based resin is MFR at 190 ° C. and a load of 2.16 kg measured according to JIS K7210 (hereinafter, the measurement value under this measurement condition is referred to as MFR in this specification). 0.5 g / 10 min or more and 40 g / 10 min or less is preferable, and 2.5 g / 10 min or more and 40 g / 10 min or less is more preferable. When the MFR is in the above range, a sealing material having excellent adhesion to other members of the solar cell module made of glass, metal, or the like can be obtained. In addition, about MFR in case a sealing material is a multilayer film, it measures by the said process with the multilayer state by which all the layers were laminated | stacked integrally, and the obtained measured value is the MFR value of the said multilayer sealing material. Shall be. Note that “MFR” in this specification refers to the value of MFR at 190 ° C. and a load of 2.16 kg measured according to JIS K7210 as described above unless otherwise specified. However, the MFR of the polypropylene resin is the value of MFR at 230 ° C. and a load of 2.16 kg according to JIS K7210.

  Here, the “polyethylene resin” in the present invention is obtained by polymerizing not only ordinary polyethylene obtained by polymerizing ethylene but also a compound having an ethylenically unsaturated bond such as α-olefin. Resin, a resin obtained by copolymerizing a plurality of different compounds having an ethylenically unsaturated bond, a modified resin obtained by grafting another chemical species to these resins, and the like.

  Of these, a silane copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer (hereinafter, also referred to as “silane copolymer”) can be preferably used. By using such a resin, it is possible to obtain higher adhesion between the sealing member and another member such as a transparent front substrate or a solar cell element.

  As the α-olefin of the linear low density polyethylene, an α-olefin having no branch is preferably used. Among these, 1-hexene and 1-heptene which are α-olefins having 6 to 8 carbon atoms are preferable. Or 1-octene is particularly preferably used. When the α-olefin has 6 to 8 carbon atoms, the solar cell module sealing material can be provided with good flexibility and good strength. As a result, the adhesiveness between the solar cell module sealing material and the transparent front substrate such as glass is further increased, and the intrusion of moisture can be suppressed.

  The silane copolymer is described in, for example, JP-A-2003-46105. By using the copolymer as a component of the solar cell module sealing material composition, it is excellent in strength, durability, etc., and weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, yield resistance In addition, it has excellent other characteristics, and has extremely excellent heat-sealability without being affected by manufacturing conditions such as thermocompression bonding for manufacturing solar cell modules. A solar cell module suitable for the above can be manufactured.

  As the silane copolymer, any of a random copolymer, an alternating copolymer, a block copolymer, and a graft copolymer can be preferably used. However, the silane copolymer is more preferably a graft copolymer. A graft copolymer obtained by polymerizing polyethylene for polymerization as a main chain and an ethylenically unsaturated silane compound as a side chain is more preferable. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to the adhesive force, the adhesion of the solar cell module sealing material to other members in the solar cell module can be improved.

  The content of the ethylenically unsaturated silane compound in constituting the copolymer of the α-olefin and the ethylenically unsaturated silane compound is, for example, 0.001% by mass or more and 15% by mass with respect to the total copolymer mass. % Or less, preferably 0.01% by mass or more and 5% by mass or less, and particularly preferably 0.05% by mass or more and 2% by mass or less. In the present invention, when the content of the ethylenically unsaturated silane compound constituting the copolymer of the α-olefin and the ethylenically unsaturated silane compound is large, the mechanical strength and heat resistance are excellent, but the content is excessive. When it becomes, it exists in the tendency which is inferior to tensile elongation, heat-fusibility, etc.

  As a crosslinking agent used as an essential component in the sealing material composition for the light-receiving surface side sealing material, known crosslinking agents, for example, various radical polymerization initiators exemplified below can be used. Examples of the radical polymerization initiator include n-butyl 4,4-di (t-butylperoxy) valerate, ethyl 3,3-di (t-butylperoxy) butyrate, 2,2-di (t-butyl). Peroxyketals such as peroxy) butane, hydroperoxides such as diisopropylbenzene hydroperoxide, 2,5-dimethyl-2,5-di (hydroperoxy) hexane; di-t-butyl peroxide, t -Butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-peroxy) hexyne-3 Dialkyl peroxides such as bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, benzo Diacyl peroxides such as ruperoxide, o-methylbenzoyl peroxide, 2,4-dichlorobenzoyl peroxide; t-butyl peroxyacetate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy Pivalate, t-butyl peroxy octoate, t-butyl peroxy isopropyl carbonate, t-butyl peroxy benzoate, di-t-butyl peroxy phthalate, 2,5-dimethyl-2,5-di (benzoyl peroxy) ) Peroxyesters such as hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexyne-3, t-butylperoxy-2-ethylhexyl carbonate; keto such as methyl ethyl ketone peroxide and cyclohexanone peroxide Organic peroxides such as peroxides, or azo compounds such as azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile), dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctate, dioctyltin dilaurate And silanol condensation catalysts such as dicumyl peroxide.

  The content of the crosslinking agent in the encapsulant composition for the light-receiving surface side encapsulant is 0.2% by mass or more and 2.0% by mass or less with respect to the total resin components in the encapsulant composition. More preferably, it is the range of 0.5 mass% or more and 1.5 mass% or less. By adding a crosslinking agent in this range, sufficient durability can be imparted to the low-density polyethylene resin used for the sealing material of the present invention.

  The encapsulant composition for the light-receiving surface side encapsulant is a polyfunctional monomer having a carbon-carbon double bond and / or an epoxy group, more preferably an allyl group or a (meth) acrylate group. It is preferable to contain a crosslinking aid which is a vinyl group. Thus, in addition to promoting an appropriate crosslinking reaction and improving the adhesion between the light-receiving surface side sealing material 2 and the light-receiving surface side glass protective substrate 1, this crosslinking aid is used for the light-receiving surface side sealing material 2 The crystallinity of the linear low-density polyethylene that forms is reduced and the transparency is maintained. Thereby, in addition to the effect of improving the adhesion, the effect of making the light receiving surface side sealing material more excellent in transparency and low temperature flexibility can be enjoyed.

  Specific examples of the crosslinking aid that can be used in the encapsulant composition for the light-receiving surface side encapsulant include triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fumarate, diallyl. Polyallyl compounds such as maleate, trimethylolpropane trimethacrylate (TMPT), trimethylolpropane triacrylate (TMPTA), ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol Poly (meth) acryloxy compounds such as diacrylate and 1,9-nonanediol diacrylate, glycidyl methacrylate containing double bond and epoxy group, 4-hydroxybutyl acrylate glycidyl ether and epoxy The containing two or more 1,6-hexanediol diglycidyl ether, and 1,4-butanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, an epoxy-based compounds such as trimethylolpropane polyglycidyl ether. These may be used alone or in combination of two or more. Among the above-mentioned crosslinking aids, it also contributes significantly to improving the glass adhesion of the sealing material, has good compatibility with linear low density polyethylene, reduces crystallinity by crosslinking, maintains transparency, TAIC can be preferably used from the viewpoint of imparting flexibility in the above.

  The content of the crosslinking aid in the encapsulant composition for the light-receiving surface side encapsulant is 0.01% by mass or more and 3% by mass or less with respect to all resin components in the encapsulant composition. Preferably, it is 0.05 mass% or more and 2.0 mass% or less. Within this range, an appropriate crosslinking reaction can be promoted to improve the adhesion between the light receiving surface side glass protective substrate 1 and the light receiving surface side sealing material 2.

  It is preferable to add a light-resistant stabilizer to the encapsulant composition for the light-receiving surface side encapsulant so as to capture radical species harmful to the polymer and prevent generation of new radicals. As the light resistance stabilizer added to the sealing material composition for the light receiving surface side sealing material, a high molecular weight type hindered amine light resistance stabilizer can be particularly preferably used.

  In general, many types of compounds are known as hindered amine light stabilizers from low molecular weight compounds to high molecular weight compounds. When used in a sealing material composition for a solar cell module, bleeding out often occurs when a low molecular weight, that is, a molecular weight of less than 1200 is used. In this case, the light transmittance is low. It becomes smaller and transparency is lowered. Since a decrease in the transparency of the encapsulant leads to a decrease in power generation efficiency of the solar cell module, it is preferable to use a high molecular weight molecular weight of 1200 or more as the light resistance stabilizer used in the encapsulant composition. As an example of a high molecular weight type hindered amine light stabilizer that can be preferably used, mention may be made of 1- [2- (4-hydroxy-2,2,6,6-tetramethylpiperidino) ethyl] butanedioate. Can do.

  About the hindered amine light-resistant stabilizer addition amount to the sealing material composition for light-receiving surface side sealing materials, 0.005 mass% or more and 0.2 mass% with respect to all the resin components in a sealing material composition. If it is less than 0.03 mass%, it is preferable that it is 0.03 mass% or more and 0.20 mass% or less. By making the content 0.005% by mass or more, the effect of stabilizing light resistance can be sufficiently obtained. Further, when the content is less than 0.2% by mass, bleeding out can be suppressed, and discoloration of the resin due to excessive addition of a hindered amine light-resistant stabilizer can also be suppressed.

  The sealing material composition for the light-receiving surface side sealing material can further contain other components. For example, ultraviolet absorbers, heat stabilizers, adhesion improvers, nucleating agents, dispersants, leveling agents, plasticizers, antifoaming agents, flame retardants, and other various fillers can be added as appropriate. The content ratio of these additives varies depending on the particle shape, density, and the like, but is preferably in the range of 0.001% by mass to 60% by mass in the encapsulant composition. By including these additives, it is possible to impart a mechanical strength that is stable over a long period of time, an effect of preventing yellowing, cracking, and the like to the encapsulant composition.

<Non-light-receiving surface side sealing material>
Non-light-receiving-side sealing member 3 is made as a 0.870 g / cm ³ or more 0.930 g / cm ³ or less polyethylene resin as a base resin of the gel fraction is formed by the 0% of the resin film.

  Thus, the non-light-receiving surface side sealing material 3 having a gel fraction of 0% can be formed as a thermoplastic sealing material as one embodiment.

  Further, as another embodiment, the non-light-receiving surface side sealing material 3 is a weak cross-link that advances a very weak cross-link (weak cross-link) that does not interfere with the film formation during the film formation and does not change the gel fraction. It can also be formed as a system sealing material. “Weak cross-linking” is a production method disclosed in detail in International Publication No. 2011/152314, and is a known film-forming technique in which very weak cross-linking proceeds while maintaining the gel fraction at about 0%. It is. In this specification, the sealing material formed by obtaining this weak crosslinking treatment is referred to as a “weakly-crosslinked sealing material” or a “weakly crosslinked sealing material”.

  Even if it is based on any of the above production methods, at least in the meaning that the crosslinking of the material resin does not proceed after film formation, these are all “non-crosslinked sealing materials” in a broad sense. is there. The solar cell module 10 is characterized in that the sealing material disposed on the non-light-receiving surface side is all a non-crosslinking sealing material in this sense in terms of its layer structure.

As above-mentioned, the non-light-receiving surface side sealing material 3 can be formed as a thermoplastic sealing material which consists of a sealing material composition which does not contain a crosslinking agent as one embodiment. In this case, the non-light-receiving surface side sealing material 3 is preferably a multilayer film composed of a plurality of layers including a core layer 31 and a skin layer 32 disposed on both outermost surfaces. In this case, the core layer 31 preferably uses a polyethylene resin having a density of 0.910 g / cm ³ or more and 0.930 g / cm ³ or less as a base resin, and the skin layer 32 has a density of 0.890 g. The base resin is preferably a polyethylene resin having a density of from / cm ^{3 to} 0.910 g / cm ^{3 and} lower than the base resin for the core layer.

  As described above, when the non-light-receiving surface side sealing material 3 is formed as a thermoplastic multilayer film, the total thickness is preferably 250 μm or more and 600 μm or less, and more preferably 300 μm or more and 550 μm or less. If the total thickness is less than 250 μm, the impact cannot be sufficiently reduced, but if the total thickness is 250 μm or more, for example, the non-light-receiving surface side sealing material 3 is thinned to a total thickness of about 250 μm. Even in this case, the molding property and the heat resistance can be combined at a sufficiently preferable level. In addition, when the total thickness exceeds 600 μm, it is difficult to obtain an effect of further improving the impact mitigation effect, it is not possible to meet the demand for thinning the solar cell module, and it is uneconomical.

  Further, the thickness of the core layer 31 in the non-light-receiving surface side sealing material 3 formed as the thermoplastic multilayer film is preferably 100 μm or more and 400 μm or less, and more preferably 250 μm or more and 350 μm or less. . In this case, the thickness of each layer of the skin layer 32 is not less than 30 μm and not more than 200 μm. By setting the thickness of each layer of the non-light-receiving surface side sealing material 3 in such a range, the heat resistance and molding characteristics of the non-light-receiving surface side sealing material 3 can be maintained in a favorable range.

As described above, the non-light-receiving surface side sealing material 3 can also be formed as a weakly crosslinked sealing material as another preferred embodiment. In this case, the non-light-receiving-side sealing member 3, a density of 0.870 g / cm ³ or more 0.900 g / cm ³ or less of the polyethylene resin as a base resin, containing a very small amount of crosslinking agent as described below It is preferable that it consists of a composition.

  When the non-light-receiving surface side sealing material 3 is formed as a weakly cross-linking type sealing material, the non-light-receiving surface side sealing material 3 may be a single-layer film, but as shown in FIG. And the multilayer film comprised by the skin layer 32 arrange | positioned on both surfaces of a core layer may be sufficient. In this case, it is within the composition range of the sealing material composition for the non-light-receiving surface side sealing material, which will be described later, and those having different compositions and component ratios can be used for each layer.

  When the non-light-receiving surface side sealing material 3 is a weakly crosslinked multilayer film, it is more preferable to use a sealing material having a different MFR for each layer. The non-light-receiving surface side sealing material 3 made of a weakly crosslinked resin film has preferable transparency, flexibility and heat resistance even when it is a single layer film. It is more preferable that the surface to be adhered is further excellent in such molding characteristics. This non-light-receiving surface side sealing material 3, which is a multilayer film having different MFRs for each layer, is disposed on the outermost layer on the side to be used in close contact with the electrode surface of the solar cell element. As described above, while maintaining the above-described preferable transparency and heat resistance, the molding characteristics on the contact surface with the solar cell element can be further enhanced.

  For example, in the non-light-receiving surface side sealing material 3 which is a weakly crosslinked multilayer film composed of three or more layers, the thickness of the outermost layer is preferably 30 μm or more and 200 μm or less. By doing in this way, while maintaining the preferable heat resistance as a sealing material, the preferable molding characteristic in an outermost layer can be provided, and also manufacturing cost can be suppressed low.

Here, the weakly cross-linking type sealing material is characterized by (i) maintaining low density and (ii) improving heat resistance but having sufficient film-forming properties in terms of its physical properties. is there. With regard to the density of the weakly crosslinked sealing material (i), the density of the light-receiving surface side sealing material 2 is approximately 0.900 g / approximately the same as the density of the low-density polyethylene resin that is the main raw material. The density difference of the resin composition before and after melt molding does not increase at cm ³ or less and is within 0.05 g / cm ³ . For this reason, transparency is maintained. On the other hand, the weakly crosslinked sealing material has an MFR of 0.1 g / 10 min or more and 1.0 g / 10 min or less with respect to the heat resistance of (ii), and the MFR difference between the resin compositions before and after melt molding. Is preferably 1.0 g / 10 min or more and 10.0 g / 10 min or less. As described above, the weakly cross-linking type sealing material has improved heat resistance while being within the range of MFR capable of being formed. Normally, there is a positive correlation between the MFR and the density of the resin. However, according to the weak cross-linking treatment, it is possible to slightly reduce the MFR within the range of the MFR that can be formed without changing the density.

  The weakly crosslinked encapsulant has a polystyrene-equivalent weight average molecular weight of 120,000 or more and 300,000 or less, and is an encapsulant after weakly crosslinked / an encapsulant composition before weakly crosslinked (uncrosslinked polyethylene-based). The ratio of the weight average molecular weight of the resin) is in the range of 1.5 to 3.0. From this, it can be understood that although it is made into a macromolecule, a dense cross-linked structure is not formed and a weak cross-link is formed. In addition, the weight average molecular weight in this invention melt | dissolves so that it may become 6 wt% of xylene, a viscosity is measured, and the weight average molecular weight is calculated | required from conversion with the polystyrene sample from the viscosity. In addition, about the molecular weight of the sealing material which is a multilayer film, the said process was performed in the multilayer state with which all the layers were laminated | stacked, and the obtained measured value was made into the weight average molecular weight of the said multilayer sealing material. To do.

  The non-light-receiving surface side sealing material 3 is formed into a film or sheet by molding a sealing material composition for a non-light-receiving surface side sealing material, which will be described in detail below, by a conventionally known method. is there. In addition, the sheet form in this invention means the film form, and there is no difference in both.

  As described above, the solar cell module 10 further increases the use efficiency of incident light by disposing a white layer on the non-light-receiving surface side of the solar cell element 6 or when the solar cell module is required to have a white appearance. Can meet the demands of design. Such a white layer can be formed by disposing the non-light-receiving surface side white sealing material 4 further outside the non-light-receiving surface side sealing material 3 in the solar cell module 10, but the non-light-receiving surface side sealing material Also by adding a white coloring material to 3 to obtain a white sealing material, a solar cell module including a white layer that can meet such a demand can be obtained. Of the two configurations described above, according to the configuration in which the latter non-light-receiving surface side sealing material 3 is a white sealing material, the solar cell module can be configured with fewer components than in the former case. In addition, the module can be made thinner. From the above, productivity and economy can be improved. Furthermore, since the white reflective layer is disposed at a position closer to the solar cell element 6, the transmitted light can be reflected more efficiently, and the solar cell module is more advantageous in optical design. Can do.

  When the non-light-receiving surface side sealing material 3 is a white sealing material, the non-light-receiving surface side sealing material layer has a three-layer structure of skin / core / skin, and only the core layer contains a white coloring material. It is preferable that the skin layer disposed on the outermost surface of the non-light-receiving surface side sealing material 3 does not contain the same coloring material. When the non-light-receiving surface side sealing material 3 is a white layer, the adhesiveness of the skin is reduced due to the influence of the white pigment by adopting a configuration in which a white coloring material such as a white pigment is contained only in the core layer. Can be suppressed.

  As the white colorant added when the non-light-receiving surface side sealing material 3 is a white sealing material, the same white pigment as that used for the non-light-receiving surface side white sealing material 4 described later can be used. Details of the white pigment that can be preferably used will be described later.

[Sealing material composition for non-light-receiving surface side sealing material]
When the non-light-receiving surface side sealing material 3 is formed as a thermoplastic sealing material, the sealing material composition for the non-light-receiving surface side sealing material used for manufacturing each layer has a different density range or the like for each layer. The composition is a base resin. Hereinafter, first, the encapsulant composition that is preferably used when the non-light-receiving surface side encapsulant 3 is formed as a thermoplastic encapsulant will be described.

  In this case, as the sealing material composition for the non-light-receiving surface side sealing material, the sealing material composition for the core layer 31 and the sealing material composition for the skin layer 32 are separately used for forming each layer. . And by molding each of the encapsulant compositions for the core layer and the skin layer, a multilayer film having a three-layer structure in which the skin layers are arranged on both outermost surfaces with a predetermined layer thickness, for example, The non-light-receiving surface side sealing material 3 shown in FIG. 3 can be manufactured.

  As a base resin of the sealing material composition for the core layer 31 of the non-light-receiving surface side sealing material 3, a low density polyethylene resin (LDPE), a linear low density polyethylene resin (LLDPE), or a metallocene linear chain Low density polyethylene resin (M-LLDPE) can be preferably used. Among these, from the viewpoint of long-term reliability of the solar cell module, a low-density polyethylene resin (LDPE) can be particularly preferably used as the composition for the core layer.

The density of the polyethylene resin used as the base resin of the sealing material composition for the core layer 31 is 0.910 g / cm ³ or more and 0.930 g / cm ³ or less, more preferably 0.920 g / cm ³ or less. It is. By setting the density of the base resin of the sealing material composition for the core layer 31 within the above range, the non-light-receiving surface side sealing material 3 can be provided with necessary and sufficient heat resistance without undergoing a crosslinking treatment. .

  The melting point of the sealing material composition for the core layer 31 is preferably 90 ° C. or higher and 135 ° C. or lower, more preferably 100 ° C. or higher and 115 ° C. or lower. By setting the melting point of the core layer 31 to the above melting point range, the heat resistance and molding characteristics of these transparent sealing materials can be maintained within a preferable range. In addition, it is possible to raise the melting | fusing point of a sealing material composition to about 135 degreeC by adding high melting point resin, such as a polypropylene, to the composition of a core layer. In this case, it is preferable that the polypropylene is contained in an amount of 5% by mass or more and 40% by mass or less with respect to all the resin components of the core layer 31.

  The polypropylene contained in the core layer 31 is preferably a homopolypropylene (homo PP) resin. Homo PP is a polymer composed only of polypropylene and has high crystallinity, and therefore has higher rigidity than block PP and random PP. By using this as an additive resin to the white core layer composition, the dimensional stability of the sealing material can be enhanced. The homo PP used as an additive resin to the white core layer composition preferably has an MFR of 5 g / 10 min or more and 125 g / 10 min or less at 230 ° C. and a load of 2.16 kg measured according to JIS K7210. . When the MFR is less than 5 g / 10 minutes, the molecular weight increases and the rigidity becomes too high, so that it is difficult to ensure the preferable and sufficient flexibility of the sealing material. On the other hand, if the MFR exceeds 125 g / 10 min, the fluidity during heating is not sufficiently suppressed, and the heat resistance and dimensional stability cannot be sufficiently imparted to the sealing material.

  The melt mass flow rate (MFR) of the polyethylene resin used as the base resin of the sealing material composition for the core layer 31 is 2.0 g / 10 min or more and 7.5 g / 10 min or less at 190 ° C. and a load of 2.16 kg. It is preferable that it is 3.0g / 10min or more and 6.0g / 10min or less. By setting the MFR of the base resin of the sealing material composition for the core layer 31 within the above range, the heat resistance and molding characteristics of the non-light-receiving surface side sealing material 3 can be maintained within a preferable range. Moreover, the processability at the time of film-forming can fully be improved and it can contribute also to the improvement of the productivity of the non-light-receiving surface side sealing material 3. FIG.

  Content of said base resin with respect to all the resin components in the sealing material composition for core layers 31 is 70 to 99 mass%, Preferably it is 90 to 99 mass%. As long as the base resin is included within the above range, other resins may be included.

  As the base resin of the sealing material composition for the skin layer 32 of the non-light-receiving surface side sealing material 3, as with the sealing material composition for the core layer 31, a low density polyethylene resin (LDPE), linear A low density polyethylene resin (LLDPE) or a metallocene linear low density polyethylene resin (M-LLDPE) can be preferably used. Among these, from the viewpoint of molding characteristics, a metallocene linear low density polyethylene resin (M-LLDPE) can be particularly preferably used as the composition for the skin layer.

The density of the polyethylene resin used as the base resin of the sealing material composition for the skin layer 32 is 0.890 g / cm ³ or more 0.910 g / cm ³ or less, more preferably, 0.899 g / cm ³ or less. By setting the density of the base resin of the sealing material composition for the skin layer within the above range, the adhesion of the non-light-receiving surface side sealing material 3 can be maintained within a preferable range.

  About melting | fusing point of the sealing material composition for skin layers 32, it is preferable that it is melting | fusing point 55 degreeC or more and 100 degrees C or less, and it is more preferable that it is melting | fusing point 80 degreeC or more and 95 degrees C or less. By making melting | fusing point of the sealing material composition for skin layers 32 into the said range, the adhesiveness of the sealing material at the time of integration as a solar cell module can be improved further reliably.

  The melt mass flow rate (MFR) of the polyethylene resin used as the base resin of the sealing material composition for the skin layer 32 is 2.0 g / 10 min or more and 7.0 g / 10 min or less at 190 ° C. and a load of 2.16 kg. It is preferable that it is 2.5 g / 10min or more and 6.0 g / 10min or less. By setting the MFR of the base resin of the sealing material composition for the skin layer 32 within the above range, the adhesion of the sealing material can be more reliably maintained within a preferable range. Moreover, the processability at the time of film formation can be sufficiently improved, and it can contribute to the improvement of the productivity of the non-light-receiving surface side sealing material 3.

  Content of said base resin with respect to all the resin components in the sealing material composition for skin layers 32 is 60 to 99 mass%, Preferably it is 90 to 99 mass%. As long as the base resin is included within the above range, other resins may be included.

Next, the encapsulant composition that is preferably used when the non-light-receiving surface side encapsulant 3 is formed as a weakly crosslinked encapsulant will be described. In this case, the sealing material composition for the non-light-receiving surface side sealing material uses low density polyethylene (LDPE) having a density of 0.900 g / cm ³ or less, preferably linear low density polyethylene (LLDPE) as the base resin. . The linear low density polyethylene is a copolymer of ethylene and α-olefin, and in the present invention, the density is preferably 0.900 g / cm ³ or less, more preferably 0.870 g / cm ³ or more. The range is 0.890 g / cm ³ or less. If it is this range, favorable transparency and heat resistance can be provided by a weak crosslinking process, maintaining sheet workability.

  Further, when the non-light-receiving surface side sealing material 3 is formed as the above-mentioned weakly crosslinked sealing material, the melt mass flow rate (MFR) of the polyethylene resin used as the base resin is 190 ° C. and the load is 2.16 kg. It is preferably 1.0 g / 10 min or more and 40 g / 10 min or less, more preferably 2 g / 10 min or more and 40 g / 10 min or less. When the MFR is in the above range, the processability during film formation can be made excellent.

  When the non-light-receiving surface side sealing material 3 is formed as the above-mentioned weakly cross-linking type sealing material, the above-mentioned base resin for all resin components in the sealing material composition for the non-light-receiving surface side sealing material used for this The content of is 50 mass% or more and 99 mass% or less, preferably 90 mass% or more and 99 mass% or less. As long as the base resin is included within the above range, the composition may contain another resin within a range that does not impair the effects of the present invention.

  When the non-light-receiving surface side sealing material 3 is manufactured by a manufacturing method that imparts heat resistance by advancing weak crosslinking, with respect to all the resin components of the sealing material composition for the non-light-receiving surface side sealing material And by adding 0.02 mass% or more and less than 0.5 mass% crosslinking agent, the preferable heat resistance can be provided to the non-light-receiving surface side sealing material 3. When the addition amount of the cross-linking agent exceeds 0.5% by mass, a gel is generated during molding and the film forming property is lowered and the transparency is also lowered. There is no limitation in particular about the kind of crosslinking agent, The crosslinking agent similar to the sealing material composition for light-receiving surface side sealing materials mentioned above can be used suitably.

  In the case of producing the non-light-receiving surface side sealing material 3 by a production method that imparts heat resistance by advancing weak crosslinking, the crosslinking aid is not used, unlike a general crosslinking treatment. It is preferable.

  All the sealing material compositions for the non-light-receiving surface side sealing material layer described above include α-olefin and an ethylenically unsaturated silane compound, similarly to the sealing material composition for the light-receiving surface side sealing material layer. More preferably, each sealing material composition contains a certain amount of a silane copolymer obtained by copolymerizing as a comonomer. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to the adhesive force, the adhesion of the non-light-receiving surface side sealing material 3 to other members in the solar cell module can be improved. . The content of the silane-modified polyethylene-based resin with respect to all the resin components is 2% by mass or more in the encapsulant composition for the core layer 31 when the thermoplastic encapsulant is used. In the sealing material composition for the skin layer 32, the content is preferably 5% by mass or more and 40% by mass or less. In particular, it is more preferable that the encapsulant composition for the skin layer contains 10% or more of silane-modified polyethylene. In addition, it is preferable that the silane modification amount in said silane modified polyethylene resin is about 1.0 mass% or more and 3.0 mass% or less. The preferable content range of the silane-modified polyethylene resin in the sealing material composition is based on the premise that the silane-modified amount is within this range, and should be finely adjusted as appropriate according to the variation of the modified amount. Is desirable.

  An adhesion improver can be appropriately added to all the sealing material compositions for the non-light-receiving surface side sealing material layer. By adding the adhesion improver, the adhesion durability with other base materials can be made higher. As the adhesion improver, a known silane coupling agent can be used, and a silane coupling agent having an epoxy group or a silane coupling having a mercapto group can be particularly preferably used.

<Non-light-receiving surface side white sealing material>
White sealing member 4 is the non-light-receiving side, similar to the non-light-receiving-side sealing member 3, made as 0.870 g / cm ³ or more 0.930 g / cm ³ or less polyethylene resin as a base resin of the gel fraction Is preferably formed of a 0% resin film. The non-light-receiving surface side white sealing material 4 can also be formed as a thermoplastic or weakly-crosslinked sealing material by the same material and manufacturing method as the non-light-receiving surface side sealing material 3.

  As shown in FIG. 4, the non-light-receiving surface side white sealing material 4 is a multilayer film including a plurality of layers including a white core layer 41 and a skin layer 42 disposed on at least one of the outermost surfaces. And only the white core layer 41 contains the coloring material.

  The non-light-receiving surface side white sealing material 4 which is a multilayer film has the same resin composition as the core layer sealing material composition of the non-light-receiving surface side sealing material 3, and further added with a white coloring material A sealing material composition for the skin layer 42 made of the same resin composition as the sealing material composition for the skin layer of the non-light-receiving surface side sealing material 3, Are produced by molding a multilayer film having a three-layer structure in which skin layers are arranged on both outermost surfaces with a predetermined layer thickness by using each of these encapsulant compositions. Can do.

  The white core layer 41 in the non-light-receiving surface side white sealing material 4 constitutes a main part as a substrate layer in the non-light-receiving surface side white sealing material 4, and the non-light-receiving surface side white sealing material in this layer In the external appearance of No. 4, a colorant such as a white pigment for developing a white external appearance is contained. The non-light-receiving surface side white sealing material 4 can contribute to the improvement of power generation efficiency of the solar cell module 10 by reflecting sunlight in the white core layer 41 as described above.

  In the solar cell module 10, even when the non-light-receiving surface side white sealing material 4 is disposed on the non-light-receiving surface side, all of the sealing materials disposed on the non-light-receiving surface side including this have a gel fraction of 0%. One of the characteristics of the layer structure is that it is a non-crosslinked sealing material.

[Encapsulant composition for non-light-receiving surface side white sealant]
The sealing material composition for the white core layer of the non-light-receiving surface side white sealing material 4 used for forming the white core layer 41 of the non-light-receiving surface side white sealing material 4 is used for the non-light-receiving surface side sealing material. It is possible to use a low-density polyethylene resin having a predetermined density range similar to that of the sealing material composition for the core layer 31 as a base resin and an inorganic white pigment such as titanium oxide added thereto.

  The sealing material composition for the white core layer of the non-light-receiving surface side white sealing material 4 contains a coloring material for expressing a preferable appearance and light reflection performance as a white sealing material. As such a coloring material, an inorganic white pigment made of an inorganic compound can be used. By including such a white pigment, when the white sealing material of the present invention is disposed on the non-light-receiving surface side of the solar cell module, the incident light into the solar cell module is reflected, and the solar cell module It is possible to improve the power generation efficiency. Further, when the white core layer 41 of the non-light-receiving surface side white sealing material 4 contains an inorganic white pigment, it not only has excellent light reflection performance in the visible light region, but also has an action of absorbing ultraviolet rays. Therefore, in the solar cell module 10 made of a glass substrate whose back side is transparent, the ultraviolet rays from the back side can be blocked to prevent the deterioration of each sealing material.

  As the inorganic white pigment, for example, calcium carbonate, barium sulfate, zinc oxide, titanium oxide and the like can be preferably used. Among these, titanium oxide can be particularly preferably used from the viewpoint of versatility.

  The white pigment preferably has a particle size of 0.2 μm or more and 1.5 μm or less. If the particle size of the white pigment is in the above range, the white layer formed from it effectively reflects near infrared rays in addition to the visible light region, so that the particles that can further contribute to the power generation efficiency improvement of the solar cell module. A typical example of a white pigment having a diameter of 0.3 μm or more and 1.5 μm or less is titanium oxide, and it is preferable to use titanium oxide as the white pigment in order to improve the reflection performance of sunlight. This inorganic white pigment is contained only in the white core layer 41, and the content in the white core layer 41 is preferably 5% by mass or more and 30% by mass or less. Moreover, the non-light-receiving surface side white sealing material 4 can suppress that the adhesiveness of the skin layer 42 falls by the influence of a white pigment by making a white pigment contain only in the white core layer 41. .

  The white pigment described above can be used as a white colorant used when the non-light-receiving surface side sealing material 3 is used as the white sealing material in the above-described manner without disposing the non-light-receiving surface-side white sealing material 4. Similarly, it can be preferably used.

<Light-receiving side glass protective substrate, Non-light-receiving side glass protective substrate>
About the light-receiving surface side glass protective substrate 1 and the non-light-receiving surface side glass protective substrate 5, various glass plate materials conventionally used as a light-transmitting substrate material constituting the solar cell module can be used without particular limitation. it can.

  While the present invention has been specifically described with reference to the embodiment, the present invention is not limited to the above embodiment, and can be implemented with appropriate modifications within the scope of the present invention.

<Manufacture of sealing material>
EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

[Manufacture of light-receiving surface side transparent sealing material (crosslinking system: sealing material A)]
Solar cell modules of Examples and Comparative Examples by mixing and melting a sealing material composition for a light-receiving surface side transparent sealing material having the following composition, and forming a film to a thickness of 450 μm by a conventional T-die method A single-layer sealing material A mainly used as a light-receiving surface side transparent sealing material was obtained. The film forming temperature was 90 ° C. to 100 ° C.
Base resin (LLDPE): a copolymer of ethylene and 1-hexene, having a density of 0.880 g / cm ³ and a melt mass flow rate (MFR) at 190 ° C. of 8 g / 10 min. polyethylene. Number average molecular weight of 77,000 in terms of polystyrene.
Cross-linking agent (TBEC): t-butylperoxy-2-ethylhexyl carbonate (manufactured by Arkema Yoshitomi, trade name Luperox TBEC). 0.7 parts by mass added to 100 parts by mass of the base resin.
Crosslinking aid (TAIC): triallyl isocyanurate (manufactured by Statomer, trade name SR533). 0.5 parts by mass added to 100 parts by mass of the base resin.
UV absorber: manufactured by Chemipro Kasei Co., Ltd., trade name KEMISORB102. Addition of 0.25 parts by mass to 100 parts by mass of the base resin.
Weathering stabilizer: Ciba Japan Co., Ltd., trade name Tinuvin 770. 0.2 parts by mass added to 100 parts by mass of the base resin.
Antioxidant: Ciba Japan Co., Ltd., trade name Irganox 1076. 0.05 parts by mass added to 100 parts by mass of the base resin.
Silane coupling agent: Shin-Etsu Chemical Co., Ltd., trade name KBM503. 0.05 parts by mass added to 100 parts by mass of the base resin.

[Manufacture of non-light-receiving surface side sealing material (thermoplastic: sealing material B1)]
The encapsulant composition raw materials described below are mixed in the following proportions (parts by mass), and the encapsulant composition for the core layer and the encapsulant composition for the skin layer of the encapsulant of Examples and Comparative Examples, respectively. It was a thing. Using each sealing material composition for a core layer and a skin layer at an extrusion temperature of 210 ° C. and a take-off speed of 1.1 m / min using a φ30 mm extruder and a film molding machine having a 200 mm wide T-die Each resin film was produced, these each resin film was laminated | stacked, and the thermoplastic sealing material provided with the core layer and the skin layer arrange | positioned on both outermost surfaces was manufactured. This was made into sealing material B1 mainly used as a non-light-receiving surface side sealing material in the solar cell module of an Example and a comparative example. The thicknesses of the sealing materials are all 450 μm in total, and the thickness ratio of each layer is such that the skin layer: core layer: skin layer thickness ratio is 1: 8: 1. did. The density of the core layer of this multilayer sheet is 0.92 g / cm ³ , and the density of the skin layer is 0.89 g / cm ³ .

The following raw materials were used as the thermoplastic sealing material composition raw material.
(Base resin for encapsulant composition for core layer)
A metallocene linear low density polyethylene resin (M-LLDPE) having a density of 0.919 g / cm ³ , a melting point of 105 ° C., and an MFR at 190 ° C. of 3.5 g / 10 min. 77 parts by mass added.
A metallocene linear low-density polyethylene resin (M-LLDPE) having a density of 0.880 g / cm ³ , a melting point of 60 ° C., and an MFR at 190 ° C. of 3.5 g / 10 min. Added 20 parts by weight.
(Base resin for encapsulant composition for skin layer)
Metallocene linear low density polyethylene resin (M-LLDPE) having a density of 0.898 g / cm ³ , a melting point of 90 ° C., and an MFR at 190 ° C. of 3.5 g / 10 min. Add 85 parts by weight.
(Other additives)
Weatherproofing agent master batch: Hindered amine light stability for 100 parts by weight of base resin (density 0.919 g / cm ³ , melting point 105 ° C., low density polyethylene resin MFR at 190 ° C. of 3.5 g / 10 min) Agent ("KEMISTAB62" (manufactured by Chemipro)): 0.6 parts by mass. UV absorber ("KEMISORB 12" (manufactured by Chemipro)): 3.5 parts by mass. UV absorber (“KEMISORB 79” (manufactured by Chemipro)): 0.6 parts by mass. The weathering agent master badge was added in an amount of 10 parts by mass to the composition for the core layer and the skin layer.
Silane-modified polyethylene resin: 2 parts by mass of vinyltrimethoxysilane with respect to 100 parts by mass of a metallocene linear low-density polyethylene resin having a density of 0.900 g / cm ³ and an MFR of 2.0 g / 10 min. A silane-modified polyethylene resin obtained by mixing 0.15 parts by mass of dicumyl peroxide as a radical generator (reaction catalyst), melting and kneading at 200 ° C. Density 0.901 g / cm ³ , MFR 1.0 g / 10 min. Melting point 100 ° C. The silane-modified polyethylene resin was added in an amount of 3 parts by mass to the core layer composition and 15 parts by mass of the skin layer composition.

[Manufacture of non-light-receiving surface side sealing material (weakly crosslinked system: sealing material B2)]
The encapsulant composition raw materials described below were mixed at the following blending ratios, and the encapsulant composition for the core layer of the encapsulant and the encapsulant composition for the skin layer of Examples and Comparative Examples, respectively. . Using each sealing material composition for a core layer and a skin layer at an extrusion temperature of 210 ° C. and a take-off speed of 1.1 m / min using a φ30 mm extruder and a film molding machine having a 200 mm wide T-die Each resin film was produced, and each of these resin films was laminated to produce a weakly-crosslinked sealing material including a core layer and a skin layer disposed on both outermost surfaces. This was made into sealing material B2 mainly used as a non-light-receiving surface side sealing material in the solar cell module of an Example and a comparative example. The thicknesses of the sealing materials are all 450 μm in total, and the thickness ratio of each layer is such that the skin layer: core layer: skin layer thickness ratio is 1: 8: 1. did. The density of the core layer of this multilayer sheet is 0.88 g / cm ³ , and the density of the skin layer is 0.88 g / cm ³ .

The following raw materials were used as raw materials for the weakly crosslinked encapsulant composition.
(Base resin for encapsulant composition for core layer)
2,5-dimethyl-2,5-di (t-butylperoxy) with respect to 100 parts by mass of M-LLDPE pellets having a density of 0.880 g / cm ³ and MFR at 190 ° C. of 3.5 g / 10 min Compound pellets were obtained by impregnating 0.041 parts by mass of hexane. 97 parts by mass added.
(Base resin for encapsulant composition for skin layer)
2,5-dimethyl-2,5-di (t-butylperoxy) with respect to 100 parts by mass of M-LLDPE pellets having a density of 0.880 g / cm ³ and MFR at 190 ° C. of 3.5 g / 10 min Compound pellets were obtained by impregnating 0.032 parts by mass of hexane. Add 80 parts by weight.
(Other additives)
Weathering agent master batch: 3.8 parts by mass of benzophenol UV absorber and hindered amine light stabilizer 5 with respect to 100 parts by mass of powder obtained by pulverizing Ziegler linear low density polyethylene having a density of 0.880 g / cm ³ Mass parts and 0.5 parts by mass of a phosphorous heat stabilizer were mixed, melted, processed, and pelletized to obtain a master batch. The weathering agent master badge was added in an amount of 5 parts by mass to the core layer and skin layer compositions.
With respect to 98 parts by mass of a metallocene linear low density polyethylene (M-LLDPE) having a density of 0.881 g / cm ³ and an MFR at 190 ° C. of 2 g / 10 minutes, , 0.1 part by mass of dicumyl peroxide as a radical generator (reaction catalyst), mixed and melted and kneaded at 200 ° C., density 0.884 g / cm ³ , MFR at 190 ° C. was 1.8 g / A silane-modified transparent resin of 10 minutes was obtained. 3 parts by mass of the silane-modified polyethylene resin was added to the composition for the core layer and 15 parts by mass to the composition for the skin layer.

[White sealing material (production of C1, C2, C3])
By mixing any of the following white pigments in a ratio of 7 parts by mass with respect to 100 parts by mass of the resin component in the core layer in each of the above-mentioned crosslinked, thermoplastic and weakly crosslinked encapsulants, A white encapsulant was produced. The crosslinked white sealing material thus obtained was designated as C1, the thermoplastic white sealing material as C2, and the weakly crosslinked white sealing material as C3.
(White pigment)
Titanium oxide with an average particle size of 0.2 μm.

[Measurement of gel fraction]
In order to evaluate the physical properties of each sealing material in an integrated state as a solar cell module, the above-mentioned measurement was performed for each sealing material sandwiched between ETFE films and subjected to crosslinking treatment by vacuum heating lamination. The gel fraction was measured by the method. As a result, the gel fraction of the cross-linking encapsulant A and the white encapsulant C1 is 60%. For the thermoplastic and weakly crosslinked sealing materials B1 to B2 and C2 to C3, the gel fraction after the heat treatment was 0%. The vacuum heating lamination conditions were the same as the conditions in the following “Manufacturing of solar cell module evaluation sample”.

<Manufacture of solar cell module evaluation samples>
Each of the sealing materials A, B1, and B2 is used as a light-receiving surface side transparent sealing material or a non-light-receiving surface side sealing material, respectively, and the white sealing materials C1 to C3 are respectively used. Samples for solar cell module evaluation of each example and comparative example were manufactured according to the configuration shown in Table 1 below by properly using the non-light-receiving surface side white sealing material. However, for Examples 3, 4 and Comparative Example 5, as shown in Table 1, any of the white sealing materials C1 to C3 is used without using the transparent sealing material as the non-light-receiving surface side sealing material. This was used as a layer structure in which this was directly laminated on the light-receiving surface side transparent sealing material.

Samples for solar cell module evaluation include a light-receiving surface side glass protective substrate (white plate tempered glass, 1700 mm × 1000 mm × 2.5 mm), a light-receiving surface side transparent sealing material (1700 mm × 1000 mm × 0.45 mm), a solar cell element, Non-light-receiving surface side sealing material (1700 mm × 1000 mm × 0.45 mm), non-light-receiving surface side white sealing material (1700 mm × 1000 mm × 0.45 mm), and non-light-receiving surface side glass protective substrate (white plate float tempered glass, 1700 mm) × 1000 mm × 2.5 mm) are sequentially laminated and then manufactured by thermocompression molding using the above-mentioned members as an integrally formed body by vacuum heating lamination, and this is used for solar cell module evaluation of Examples and Comparative Examples A sample was used. Regarding the solar cell elements, the following solar cell elements were prepared, and 60 solar cell elements of the same type were electrically connected in series with a connecting member for one solar cell module evaluation sample.
(Vacuum heating lamination conditions) (a) Vacuum drawing: 6.0 minutes
(B) Pressurization (0 kPa to 70 kPa): 1.5 minutes
(C) Pressure holding (70 kPa): 11.0 minutes
(D) Temperature 165 ° C
(Solar cell element)
A crystalline silicon solar cell element manufactured using a polycrystalline silicon substrate. (Motech, IM156B3)

<Evaluation of solar cell element protection performance during laminating>
About each said solar cell module evaluation sample, it measured with the EL light emission tester, and evaluated the protective performance of the solar cell element at the time of a lamination process. The evaluation results are shown in Table 1 as “cell cracking”.
(Evaluation criteria) ○: No cracks on the entire surface of all solar cell elements
Δ: There is a crack in a part of the surface of the solar cell element, but light emission can be confirmed.
×: There is a place where light emission cannot be confirmed due to cracks

<Evaluation of cell displacement suppression effect during laminating>
About each said solar cell module evaluation sample, the cell flow suppression effect test was evaluated by visual observation by the following evaluation criteria. The evaluation results are shown in Table 1 as “cell deviation”.
(Evaluation criteria) (circle): The space | interval of the cell connected before and behind vacuum heating lamination has not changed.
X: The interval between the connected cells before and after the vacuum heating lamination is changed.

<Evaluation of wraparound effect during laminating>
About each said solar cell module evaluation sample, the wraparound suppression effect test was evaluated by visual observation by the following evaluation criteria. The evaluation results are shown as “wraparound” in Table 1.
(Evaluation criteria) (circle): The white sealing material does not wrap around to the light-receiving surface side of a solar cell element.
X: The white sealing material wraps around the light-receiving surface side of the solar cell element.

<Evaluation of heat resistance of solar cell module>
[Heat-resistant creep test]
In order to measure the heat resistance of the solar cell module, a heat resistance creep test was performed. Each sealing material of A, B, C1, and C2 cut into 5 cm × 7.5 cm on a glass plate (white plate float semi-tempered glass JPT3.2 150 mm × 150 mm × 3.2 mm) is a combination described in Table 2 In the order of light-receiving surface side sealing material-non-light-receiving surface-side sealing material-white sealing material, or light-receiving surface side sealing material-white sealing material, three or two sheets are placed on top of each other. The same glass plate as in Evaluation Example 1 of 5 cm × 7.5 cm was placed on top of each other, and vacuum heating laminator treatment was performed under the same conditions as in the above <Manufacture of solar cell module evaluation sample> to prepare a module heat resistance evaluation sample. Thereafter, the large format glass was placed vertically and allowed to stand at 105 ° C. for 12 hours, and the moving distance (mm) of the 5 cm × 7.5 cm glass plate after the standing was measured and evaluated. Evaluation was performed according to the following criteria.
(Evaluation criteria) ○: 0.00 mm or more and less than 0.05 mm
Δ: 0.05 mm or more and less than 1.0 mm
X: 1.0 mm or more The evaluation results are shown in Table 2 as “heat resistance”.

<Evaluation of heat resistance of sealing material (reference)>
As a reference test, a heat-resistant creep test was performed to measure the heat resistance of each sealing material. A glass plate (white plate float semi-tempered glass JPT3.2 150 mm × 150 mm × 3.2 mm), each of the sealing materials A, B1, B2, C1 to C3 cut out to 5 cm × 7.5 cm is placed on top of each other. From the top, the same glass plate as in Evaluation Example 1 of 5 cm × 7.5 cm was placed on top of each other, subjected to vacuum heating laminator treatment under the same conditions as in the above <Manufacture of solar cell module evaluation sample>, and a heat resistance evaluation sample was prepared. . Thereafter, the large format glass was placed vertically and allowed to stand at 105 ° C. for 12 hours, and the moving distance (mm) of the 5 cm × 7.5 cm glass plate after the standing was measured and evaluated. Evaluation was performed according to the following criteria.
(Evaluation criteria) ○: 0.00 mm
Δ: More than 0.00mm and less than 1.0mm
X: 1.0 mm or more The evaluation results are shown in Table 3 as “heat resistance”.

  From Table 2, it can be seen that the solar cell module of the present invention has sufficient heat resistance in the double-sided glass protective substrate type solar cell module excellent in durability and barrier properties. In this regard, according to the results in Table 3, as a single sealing material sheet, a thermoplastic or weakly crosslinked sealing material sheet that is not necessarily sufficient in heat resistance is used. Even if it exists, it turns out that the heat resistance as the whole solar cell module is fully ensured by combining with a bridge | crosslinking type sealing material sheet.

  And the solar cell module of the present invention ensures sufficient heat resistance by optimizing the combination of the encapsulant sheets in this way, and as shown in Table 1, the white portion wraps around and cell cracks during lamination. It can be seen that this is an extremely excellent double-sided glass protective substrate type solar cell module capable of sufficiently suppressing the above.

DESCRIPTION OF SYMBOLS 1 Light-receiving surface side glass protective substrate 2 Light-receiving surface side sealing material 21 Core layer 22 Skin layer 3 Non-light-receiving surface side sealing material 31 Core layer 32 Skin layer 4 Non-light-receiving surface side white sealing material 41 White core layer 42 Skin layer 5 Non-light-receiving surface side glass protective substrate 6 Solar cell element 10 Solar cell module

Claims (10)

A double-sided glass protective substrate type solar cell module in which a light-receiving surface side glass protective substrate, a light-receiving surface side sealing material, a solar cell element, a non-light-receiving surface side sealing material, and a non-light-receiving surface side glass protective substrate are sequentially laminated. There,
The light-receiving surface side sealing material has a density of 0.900 g / cm ³ or less as a base resin, and has a gel fraction of 20% to 80%,
The non-light-receiving-side sealing member is made as a 0.870 g / cm ³ or more 0.930 g / cm ³ or less polyethylene resin as a base resin of the gel fraction is 0%, the solar cell module. The non-light-receiving surface side sealing material is a multilayer sealing material constituted by a plurality of layers including a core layer and a skin layer disposed on both outermost surfaces, and the core layer has a density of 0.00. 910 g / cm ³ or more 0.930 g / cm ³ becomes as follows polyethylene resin as a base resin of the skin layer and the density of 0.890 g / cm ³ or more 0.910 g / cm ³ or less of the polyethylene resin-based resin The solar cell module according to claim 1.   In the non-light-receiving surface side sealing material, the core layer has a thickness of 100 μm or more and 600 μm or less, the melting point of the core layer is 90 ° C. or more and 135 ° C. or less, and the thickness of each layer of the skin layer is 30 μm. The solar cell module according to claim 1 or 2, wherein the skin layer has a melting point of not less than 200 µm and not less than 55 ° C and not more than 100 ° C. Wherein the non-light-receiving side encapsulant becomes a density 0.870 g / cm ³ or more 0.900 g / cm ³ or less of the polyethylene resin as the base resin, is substantially free of cross-linking aid, conforming to JIS K7210 The solar cell module according to claim 1, wherein the solar cell module is a weakly crosslinked encapsulant having an MFR measured at 190 ° C. and a load of 2.16 kg of 0.1 g / 10 min to 1.0 g / 10 min.   The silane copolymer formed by copolymerizing α-olefin and an ethylenically unsaturated silane compound as a comonomer is contained in the light-receiving surface side sealing material and the non-light-receiving surface side sealing material. The solar cell module according to any one of the above.   The non-light-receiving surface side sealing material is a multilayer white sealing material composed of a plurality of layers including a white core layer and a skin layer disposed on the outermost surface, and only in the white core layer The solar cell module according to any one of claims 1 to 5, wherein a white coloring material is contained.   The solar cell module according to claim 6, wherein polypropylene is contained in the white core layer in an amount of 5% by mass to 40% by mass with respect to all resin components of the white core layer.   The polypropylene contained in the white core layer is a homopolypropylene having an MFR of 5 g / 10 min to 125 g / 10 min at 230 ° C. and a load of 2.16 kg measured according to JIS K7210. Solar cell module. Between the non-light-receiving surface side sealing material and the non-light-receiving surface side glass protective substrate, further, a non-light-receiving surface side white sealing material is laminated,
The non-light-receiving surface side white sealing material is a multilayer sealing material composed of a plurality of layers including a white core layer and a skin layer disposed on the outermost surface, and only the white core layer. The solar cell module according to any one of claims 1 to 5, wherein a white coloring material is contained. It is a manufacturing method of the solar cell module of the double-sided glass protection substrate type according to any one of claims 1 to 9,
An uncrosslinked sealing material formed by forming a sealing material composition containing a low-density polyethylene having a density of 0.900 g / cm ³ or less, a crosslinking agent, and a crosslinking aid, and having a gel fraction of 20 The step of obtaining the light-receiving surface side glass protective substrate by performing a crosslinking treatment so as to be not less than 80% and not more than 80%,
About the said non-light-receiving surface side sealing material, the manufacturing method of a solar cell module which does not perform a crosslinking process after film forming.

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