JP2016039363A - Seal-material composition for solar battery module, sealant, and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealant for a non-light receiving surface side of a solar battery module, which can contribute to the enhancement of a heat dissipation performance of a solar battery module, and which can prevent a solar battery module power generation efficiency from being lowered.SOLUTION: A seal-material composition for a solar battery module comprises: a base resin (A); a thermally conductive resin(B); and thermally conductive inorganic particles (C). The base resin (A) is a polyethylene-based resin having a density of 0.870 to less than 0.930 g/cm, of which the content in the seal-material composition is 50-90 mass%. The thermally conductive resin(B) is a thermoplastic resin having a density of 0.930 to 0.980 g/cm, of which the content in the seal-material composition is 10-50 mass%. The thermally conductive inorganic particles (C) are made of an inorganic substance having a thermal conductivity of 1 W/mK or larger, of which the content in the seal-material composition is 6-35 mass%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sealing material composition for a solar cell module, a sealing material for a solar cell module using the composition, and a solar cell module using the sealing material. More specifically, the present invention relates to a solar cell module sealing material excellent in heat dissipation and a solar cell module using the same.

  In recent years, solar cells as a clean energy source have attracted attention due to the growing awareness of environmental issues. The solar cell module that constitutes the solar cell includes a solar cell element, and this solar cell element plays a role of converting light energy such as sunlight into electric energy. As this solar cell element, a single crystal or polycrystal silicon cell (crystalline silicon cell), a thin film cell using amorphous silicon, a compound semiconductor, or the like is used.

  Generally, a solar cell module is formed by sequentially laminating a transparent front substrate, a light-receiving surface side sealing material, a solar cell element, a non-light-receiving surface side sealing material, and a protective member on the back surface side that is arranged as necessary. Manufactured by a lamination method in which vacuum suction is applied to thermocompression bonding.

  It is known that the power generation efficiency of a solar cell element that generates electricity in a solar cell module generally decreases with increasing temperature. A decrease in power generation efficiency due to a rise in temperature is about 0.50% for every 1 ° C. increase in crystal type silicon solar cell elements, which is said to be relatively small due to the rise in temperature. Even in the element, it decreases by about 0.25% every time the temperature rises by 1 ° C. In other words, in a place with strong sunlight where solar power generation should be advantageous, the solar cell module is heated by sunlight at the same time, and the temperature in the module rises excessively. It may cause a phenomenon that power generation efficiency is not exhibited.

  As a method for suppressing the temperature rise of such a solar cell element, for example, a heat dissipation structure composed of a heat transfer member having high thermal conductivity, a heat dissipation fin, or the like is installed on the outermost layer side on the non-light-receiving surface side of the solar cell module And the solar cell module which aims at suppression of a temperature rise by this is disclosed. (See Patent Literature 1 and Patent Literature 2) Further, in Non-Patent Literature 1, solar power generation in which a cast product of aluminum or aluminum alloy (hereinafter also referred to as “aluminum cast product”) is provided on the non-light-receiving surface of the solar cell module. A photo of the facility is also disclosed.

  However, as a layer configuration of the solar cell module including the heat dissipation structure, a non-light-receiving surface side sealing material made of a resin film having low thermal conductivity is disposed between the heat dissipation structure and the solar cell element. In this case, the sealing material for the non-light-receiving surface side becomes a bottleneck on the heat conduction path for promoting heat radiation from the inside of the module to the outside. In many cases, the heat dissipation performance of the entire solar cell module was insufficient.

  On the other hand, as a means for increasing the thermal conductivity of the sealing material for the non-light-receiving surface side, there is a sealing material sheet obtained by adding a large amount of an inorganic material having high thermal conductivity to the resin composition forming the sealing material. Proposed. However, this sealing material sheet makes it an essential constituent requirement to add a larger amount of inorganic material than the amount generally required for various fillers. Therefore, the resin substrate surface may be deteriorated and the adhesion may be lowered due to the bleed-out of the inorganic particles, and the material cost is not preferable, and further improvement measures have been demanded.

JP 09-186353 A Japanese Patent Application Laid-Open No. 11-036540 JP 2012-79988 A

ASAKAWA Hatsuo, “-Mega Solar Construction Report P4”, [online], May 27, 2008, Asakawa Solar Power Station-Yatsugatake-Hokuto City Oizumi, [February 12, 2012 search], Internet <URL: http: // www. mt8. ne. jp / ~ sun / 2008/20080323. html>

  The present invention has been made in view of the above situation, and it is possible to improve the heat dissipation performance of the solar cell module while avoiding risks such as low adhesion due to the addition of a large amount of inorganic particles and an increase in manufacturing cost. It is an object of the present invention to provide a sealing material for the non-light-receiving surface side of a solar cell module that can contribute to the reduction in power generation efficiency of the solar cell module.

  As a result of intensive studies, the present inventors have made a polyethylene resin having a low thermal conductivity such as low density polyethylene (LDPE) but excellent flexibility and the like as a base resin. For example, by using a sealing material composition formed by adding a heat conductive resin having a relatively high heat conductivity such as high density polyethylene (HDPE), avoiding excessive addition of heat conductive inorganic particles, The present inventors have found that the above problems can be solved and have completed the present invention. More specifically, the present invention provides the following.

(1) A sealing material composition for a solar cell module, comprising a base resin (A), a heat conductive resin (B), and heat conductive inorganic particles (C), wherein the base resin ( a) is a polyethylene resin density of less than 0.870 g / cm ³ or more 0.930 g / cm ^3, the content of the sealing material composition is equal to or less than 50 wt% to 90 wt%, The thermally conductive resin (B) is a thermoplastic resin having a density of 0.930 g / cm ³ or more and 0.980 g / cm ³ or less, and the content in the sealing material composition is 10% by mass or more and 50%. It is below, Comprising: The said heat conductive inorganic particle (C) consists of an inorganic substance whose heat conductivity is 1 W / mK or more, and content in the said sealing material composition is 6 mass% or more and 35 mass% or less. The sealing material composition for solar cell modules.

  (2) The encapsulant composition according to (1), wherein the thermally conductive inorganic particles (C) are made of an inorganic material having a thermal conductivity of 5 W / mK or more.

  (3) The encapsulant composition according to (1) or (2), wherein the thermally conductive inorganic particles (C) are titanium oxide.

  (4) The sealing material composition according to any one of (1) to (3), wherein the base resin (A) is a metallocene linear low-density polyethylene.

  (5) The sealing material composition according to any one of (1) to (4), further comprising a copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer.

  (6) A sealing material for a solar cell module, which is a resin film formed by melt-molding the sealing material composition according to any one of (1) to (5).

  (7) The sealing material according to (6), wherein the thermal conductivity is 0.35 W / mK or more.

  (8) The sealing material according to (6) or (7), which has a thickness of 100 μm or more and 250 μm or less.

(9) A multilayer film having a three-layer structure consisting of an intermediate layer and an outermost layer laminated on both surfaces of the intermediate layer, and having a density of 0.870 g / cm ³ or more in a composition ratio when converted to a single-layer bulk The content of the polyethylene resin of less than 930 g / cm ³ is 50% by mass or more and 90% by mass or less, and the content of the thermoplastic resin having a density of 0.930 g / cm ³ or more and 0.980 g / cm ³ or less. The sealing material according to any one of (6) to (8), which is 10% by mass or more and 50% or less.

  (10) A solar cell module in which the sealing material according to any one of (6) to (9) is disposed on the non-light-receiving surface side of the solar cell element.

  (11) The solar cell module according to (10), wherein a heat dissipation structure is disposed on the outermost layer side on the non-light-receiving surface side of the solar cell module via the sealing material.

  According to the present invention, it is possible to contribute to the heat dissipation of the solar cell module while avoiding the risk and cost increase of adhesion due to the addition of a large amount of inorganic particles, thereby reducing the solar cell module power generation efficiency. It is possible to provide a sealing material for the non-light-receiving surface side that can be prevented from being reduced.

It is a cross-sectional schematic diagram which shows an example of the laminated constitution of the solar cell module using the sealing material of this invention.

<Encapsulant composition>
As an example, the solar cell module sealing material (hereinafter also simply referred to as “sealing material”) of the present invention is a non-light-receiving surface of the solar cell element 3 in the solar cell module 10 as shown in FIG. It is used as the sealing material 1 for the non-light-receiving surface side arrange | positioned at the side. And this sealing material is characterized by being capable of imparting excellent heat dissipation performance to the solar cell module. And the sealing material composition for solar cell modules of this invention used for manufacturing such a sealing material (henceforth a simple "sealing material composition") consists of low density polyethylene etc. A base resin (A), a thermally conductive resin (B) having a higher density and a higher thermal conductivity than the base resin (A), and thermally conductive inorganic particles (C) made of titanium oxide or the like, It can be obtained by blending at a predetermined content ratio. In addition, the sealing material composition of this invention is a thermoplastic composition which does not contain a crosslinking agent.

[Base resin (A)]
The polyethylene resin used as the base resin (A) is preferably a polyethylene resin having a relatively low density as a resin component constituting the encapsulant composition. Specifically, density 0.910 g / cm ³ or less, can be preferably used 0.870 g / cm ³ or more 0.890 g / cm ³ or less of low density polyethylene (LDPE). The base resin (A) has a melting point of 70 ° C. or lower. In addition, the density of said polyethylene-type resin used as base resin (A) can be specified also by measuring the melting | fusing point in the sealing material which is a finished product. Specifically, if the molecular structure of the resin contained in the encapsulant can be identified by IR or the like, the density can be identified from the melting point by confirming the melting point of the resin by DSC. In addition, since the amount of heat detected by DSC is quantitative, it is possible to specify the content ratio when resins having different densities are mixed as the material resin. This also applies to the following heat conductive resin (B).

  The polyethylene resin used as the base resin (A) is more preferably a copolymer of ethylene and α-olefin, and linear low density polyethylene (LLDPE) in the above density range can be used. The content of the base resin (A) in the sealing material composition is 50% by mass to 90% by mass, and preferably 70% by mass to 80% by mass. By setting the type and density range of the base resin (A) and the content in the encapsulant composition as described above, preferable flexibility can be imparted to the encapsulant.

  As the base resin (A), it is more preferable to use a metallocene linear low density polyethylene (M-LLDPE). M-LLDPE is synthesized using a metallocene catalyst that is a single site catalyst. Such polyethylene has few side chain branches and a uniform distribution of comonomer. For this reason, molecular weight distribution is narrow and it is possible to make it the above ultra-low density. In addition, since the crystallinity distribution is narrow and the crystal sizes are uniform, not only a large crystal size does not exist, but also the crystallinity itself is low due to the low density. For this reason, it excels in processability and flexibility when processed into a sheet.

The melt mass flow rate (MFR) of the polyethylene resin used as the base resin (A) is preferably 1.0 g / 10 min to 40 g / 10 min at 190 ° C. and a load of 2.16 kg, and preferably 2 g / 10 min. More preferably, it is 40 g / 10 minutes or less. When the MFR is in the above range, a sealing material composition having excellent processability during film formation can be obtained. In addition, unless otherwise indicated, MFR in this specification is a value obtained by the following method.
MFR (g / 10 min): Measured according to JIS K7210. Specifically, the synthetic resin was heated and pressurized at 190 ° C. in a cylindrical container heated by a heater, and the amount of resin extruded per 10 minutes from an opening (nozzle) provided at the bottom of the container was measured. . The test machine used was an extrusion plastometer, and the extrusion load was 2.16 kg.

[Thermal conductive resin (B)]
The thermoplastic resin used as the heat conductive resin (B) is preferably a resin having a relatively high density as a resin component constituting the sealing material composition. Specifically, density 0.920 g / cm ³ or more 0.970 g / cm ³ or less of polyethylene, it preferably using 0.935 g / cm ³ or more 0.965 g / cm ³ or less of high density polyethylene (HDPE) Can do. Moreover, it is preferable that melting | fusing point of a heat conductive resin (B) is 125 degreeC or more. Further, as the heat conductive resin (B), other thermoplastic resins in the above density range can also be used. The content of the heat conductive resin (B) in the sealing material composition is 10% by mass or more and 50% by mass or less, preferably 15% by mass or more and 35% by mass or less. Sufficient heat resistance while maintaining the flexibility of the base resin (A) by keeping the type and density range of the heat conductive resin (B) and the content in the sealing material composition as described above. And the heat conductivity required in order to exhibit the effect of this invention can be provided in a sealing material.

  When the content of the heat conductive resin (B) in the encapsulant composition is less than 10% by mass, the heat dissipation as the encapsulant according to the present invention is insufficient, while the heat conductive resin (B ) Exceeds 50% by mass, the flexibility as a sealing material becomes insufficient. Further, by using a polyethylene resin as the base resin (A) as the heat conductive resin (B), good moldability and dispersibility can be obtained due to high compatibility between the two resins.

  As the heat conductive resin (B), in addition to the polyethylene resin, other thermoplastic resins having a melting point in the range of about 125 ° C. or more and 170 ° C. or less can be used. As an example, an olefin-based elastomer that is a thermoplastic elastomer in which ethylene-propylene rubber (EPDM, EPM) is finely dispersed in polypropylene resin (PP) can be preferably used. The olefin-based elastomer is incompatible with polyethylene, but has high flexibility and heat resistance, and therefore can impart favorable flexibility and heat resistance to the sealing material. And the embrittlement characteristic peculiar to PP can be supplemented with a polyethylene resin used as the base resin (A). Therefore, the olefin-based elastomer can be preferably used as the heat conductive resin (B).

  When polyethylene is used as the heat conductive resin (B), the melt mass flow rate (MFR) of the polyethylene resin is preferably from 0.1 g / 10 min to 40 g / 10 min at 190 ° C. and a load of 2.16 kg. More preferably, it is 0.1 g / 10 min or more and 15 g / 10 min or less. When the MFR of the thermally conductive resin (B) is in the above range, the sealing ability can be imparted with excellent heat resistance and excellent durability based on the sealing material as well as excellent processability during film formation. It can be set as a stopping material composition.

[Thermal conductive inorganic particles]
As the thermally conductive inorganic particles (C), at least particles composed of an inorganic substance having a higher thermal conductivity than the base resin or the thermally conductive resin that is a resin component of the encapsulant composition can be used as appropriate. More specifically, the thermally conductive inorganic particles (C) are preferably made of an inorganic material having a thermal conductivity of at least 1 W / mK or more, and are made of an inorganic material having a thermal conductivity of 5 W / mK or more. More preferably. Content in the sealing material composition of such a heat conductive inorganic particle (C) shall be 6 mass% or more and 35 mass% or less. By limiting the content in the sealing material composition of the thermally conductive inorganic particles (C) made of an inorganic material having a high thermal conductivity to the above range, the adhesiveness of the sealing material is not impaired. The sealing material can be provided with desired thermal conductivity. When the content of the thermally conductive inorganic particles (C) in the encapsulant composition is less than 6% by mass, the effect of improving the heat dissipation as the encapsulant according to the present invention becomes insufficient, while the thermal conductivity. When the same content of the inorganic particles (C) exceeds 35% by mass, there is a problem in that the film-forming property is lowered or the smoothness of the sheet of the sealing material is lowered due to bleeding out.

  Specific examples of inorganic materials having high thermal conductivity that can be used as the thermally conductive inorganic particles (C) include titanium oxide (thermal conductivity 5.12 W / mK), calcium carbonate (thermal conductivity 3.59 W / mK). , Barium sulfate (thermal conductivity 1.31 W / mK), silicon dioxide (thermal conductivity 7.6 W / mK), and the like. Among these, by adding a white pigment to the encapsulant composition, titanium oxide that can contribute to the improvement of the light reflectivity and design of the encapsulant sheet disposed on the non-light-receiving surface side, The heat conductive inorganic particles (C) used in the sealing material composition of the present invention can be particularly preferably used.

  Here, generally, the addition of inorganic particles into the sealing material composition tends to reduce the base material adhesion of the sealing material. In the sealing material composition of the present invention, the improvement in the thermal conductivity of the sealing material is expressed mainly by optimizing the composition of the resin component in the sealing material composition. Thereby, the addition of the heat conductive inorganic particles (C) is sufficient as long as an auxiliary effect can be obtained. Therefore, the addition amount of the heat conductive inorganic particles (C) can be suppressed to the necessary minimum, and the decrease in the adhesion of the sealing material due to the excessive addition of the inorganic particles can be avoided.

[Silane-modified polyethylene resin]
In addition, in addition to said base resin (A) and heat conductive resin (B), the sealing material composition of this invention copolymerizes (alpha) -olefin and an ethylenically unsaturated silane compound as a comonomer. It is more preferable to contain a certain amount of a silane copolymer (hereinafter also referred to as “silane-modified polyethylene resin”). The silane-modified polyethylene resin is obtained by graft-polymerizing an ethylenically unsaturated silane compound as a side chain to linear low-density polyethylene (LLDPE) or the like as a main chain. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to the adhesive force, the adhesion of the sealing material to other members in the solar cell module can be improved. The content of the silane-modified polyethylene resin in the sealing material composition is preferably 5% by mass or more and 20% by mass or less.

  The silane-modified polyethylene resin can be produced, for example, by the method described in JP-A-2003-46105. By using the resin as a component of a sealing material composition for a solar cell module, strength and durability can be increased. In addition, it has excellent weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, yield resistance, and other characteristics, and also affects manufacturing conditions such as thermocompression bonding for manufacturing solar cell modules. It is possible to manufacture solar cell modules that have extremely excellent heat-sealability without being received, that are stable, low-cost, and suitable for various applications.

  Examples of ethylenically unsaturated silane compounds to be graft polymerized with linear low density polyethylene include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentyloxysilane , One or more selected from vinyltriphenoxysilane, vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane be able to.

  The graft amount, which is the content of the ethylenically unsaturated silane compound, is, for example, 0.001 to 15 masses with respect to a total of 100 mass parts of all the resin components in the sealing material composition containing other polyethylene-based resins described later. Part, preferably 0.01 to 5 parts by mass, particularly preferably 0.05 to 2 parts by mass. In the present invention, when the content of the ethylenically unsaturated silane compound is large, the mechanical strength and heat resistance are excellent. However, when the content is excessive, the tensile elongation and heat-fusibility tend to be inferior.

[Other ingredients]
In addition to the above silane-modified polyethylene resin, the polyethylene resin used in the encapsulant composition of the present invention is not only a normal polyethylene resin obtained by polymerizing ethylene, but also an α-olefin and the like. Obtained by polymerizing a compound having an ethylenically unsaturated bond, a resin obtained by copolymerizing a plurality of different compounds having an ethylenically unsaturated bond, and grafting another chemical species to these resins The resulting modified resin or the like can be used as appropriate.

  Further, the sealing material composition may further contain other components. For example, a weathering master batch for imparting weather resistance to a sealing material for a solar cell module produced from the sealing material composition for a solar cell module of the present invention, various fillers, a light stabilizer, ultraviolet absorption Components such as an agent and a heat stabilizer are exemplified. These contents vary depending on the particle shape, density, and the like, but are preferably in the range of 0.001 to 5 mass% in the encapsulant composition. By including these additives, it is possible to impart a long-term stable improvement in mechanical strength, an effect of preventing yellowing, cracking, and the like to the sealing material made of the sealing material composition.

  A weatherproof masterbatch is obtained by dispersing a light stabilizer, an ultraviolet absorber, a heat stabilizer and the above-mentioned antioxidant in a resin such as polyethylene, and adding this to a sealing material composition. Thus, good weather resistance can be imparted to the encapsulant. The weatherproof masterbatch may be prepared and used as appropriate, or a commercially available product may be used. These light stabilizers, ultraviolet absorbers, heat stabilizers and antioxidants can be used alone or in combination of two or more. In addition, as resin, such as polyethylene used for a weatherproof masterbatch, LLDPE etc. similar to base resin (A) may be sufficient, and other resin may be sufficient.

  Further, as other components used in the sealing material composition for the solar cell module of the present invention, in addition to the above, an adhesion improver such as a silane coupling agent, a nucleating agent, a dispersing agent, a leveling agent, a plasticizer, Examples include an antifoaming agent and a flame retardant.

In the sealing material composition of the present invention described above, the content ratio of the base resin (A) and the heat conductive resin (B) in the resin component is in the range of 90:10 to 50:50. Preferably there is. The average density of the resin component of the sealing material composition is preferably 0.900 g / cm ³ or more 0.930 g / cm ³ or less.

<Encapsulant>
The sealing material of this invention is arrange | positioned between the non-light-receiving surface side of a solar cell element, Comprising: Between the back surface side members arrange | positioned at the outermost layer of the non-light-receiving surface side of a solar cell module. The back side member is not limited, but is preferably a heat dissipation structure such as a heat sink of an aluminum cast product. Since the sealing material of the present invention is disposed on the non-light-receiving surface side of the solar cell element, transparency is not particularly required, but it has a high thermal conductivity. The encapsulant of the present invention having such properties is obtained by melt-molding the above encapsulant composition by a conventionally known method to form a single-layer or multilayer sheet or film. In addition, the sheet form in this invention means the film form, and there is no difference in both.

  The sealing material is formed into a sheet by various molding methods such as injection molding, extrusion molding, hollow molding, compression molding, and rotational molding, which are usually used in ordinary thermoplastic resins. In addition, as an example of the sheet forming method when the sealing material is a multilayer film, a method of forming by co-extrusion using two or more melt-kneading extruders can be given.

  However, in any of the above molding methods, the melt molding temperature in the production of the sealing material using the sealing material composition of the present invention is the same as that of the heat conductive resin (B) contained in the sealing material composition. It is preferable that it is melting | fusing point +30 degreeC or more. Specifically, a high temperature of 175 to 230 ° C. is preferable, and a high temperature in the range of 190 to 210 ° C. is more preferable. Since the sealing material composition of the present invention is a thermoplastic composition that does not contain a crosslinking agent, it is not necessary to consider inadequate control of the progress of crosslinking during melt molding. As a result, in the production of the encapsulant of the present invention, the solution is solved from the temperature limitation in the case of using a thermosetting encapsulant composition that requires a conventional crosslinking treatment, which improves productivity. Therefore, the melt molding temperature can be set in a higher temperature range.

  The sealing material of this invention is a multilayer film formed by laminating | stacking the single layer film which consists of said sealing material composition, or the single layer film which consists of said sealing material composition. The thickness of the sealing material of the present invention is preferably 150 μm or more and 300 μm or less, and more preferably 150 μm or more and 250 μm or less. The sealing material of this invention can maintain the preferable heat dissipation performance as a sealing material sheet by setting thickness to 300 micrometers or less. Further, as shown later, when it is arranged facing the heat dissipating structure arranged in the outermost layer of the solar cell module, even if it is 150 μm or less in thickness, it should have a thickness of at least 100 μm or more. For example, the function of protecting the solar cell element from an impact from the outside of the module is sufficient, and by using such a thin sealing material, the heat dissipation performance of the solar cell module can be further enhanced. In particular, when the sealing material of the present invention is a multilayer film having a three-layer structure, the thickness ratio of each layer is preferably about 1: 10: 1 to 1: 16: 1.

  When the sealing material of this invention is a multilayer film, the sealing material composition which shape | molds each single layer film laminated | stacked as a multilayer film is a base resin (A), a heat conductive resin (B), and As long as the total content of the encapsulant composition is 75% or more, encapsulant compositions having different compositions and component ratios can be used for each layer.

  In addition, the sealing material of the present invention is generally used in a solar cell module with one surface in close contact with the electrode on the non-light-receiving surface side of the solar cell element. In that case, it is preferable that a sealing material has a high molding characteristic which can express high adhesiveness especially about the surface closely_contact | adhered with the electrode surface of a solar cell element irrespective of the unevenness | corrugation of this electrode surface. Even when the sealing material of the present invention is a single-layer sealing material, it can have preferable flexibility and heat resistance, but the content of the heat conductive resin (B) for each layer is optimal. By forming a layer with a relatively low content of the heat conductive resin (B) in close contact with the electrode surface of the solar cell element and placing it in the outermost layer on the side to be used, heat resistance preferable as a sealing material While maintaining the properties, the molding characteristics in the contact surface with the solar cell element can be further enhanced. For example, when the thickness of the outermost layer is 60 μm or less in total, the outermost layer may be formed of a resin that does not contain the heat conductive resin (B).

  For example, when the sealing material is a multilayer film having a three-layer structure, the outermost layer may be a transparent layer without adding the heat conductive inorganic particles (C). Even in such a three-layer sealing material, if the average value of the content ratio of each composition in each layer is within the range of the present invention, that is, the composition ratio at the time of single layer bulk conversion is the present invention. If it is within the range, it is within the scope of the present invention regardless of the layer structure.

  As described above, the sealing material of the present invention is intended to improve the power generation efficiency by reflecting the sunlight rays that are not directly incident on the solar cell elements and guiding them again to the solar cell elements, or to improve the design. As a white sealing material. The encapsulant composition of the present invention uses a relatively high density resin such as HDPE as the heat conductive resin (B), so that the encapsulant composition is composed only of a low density polyethylene resin. Although it can be said that there is no practical problem as compared with a sealing material using, the transparency tends to be slightly inferior. However, for example, in the case where the white sealing material excellent in reflection efficiency and designability is used by being arranged on the non-light-receiving surface side of the solar cell module element, there is no problem of slight deterioration in transparency. Rather, in such a case, the sealing material of the present invention maintains the power generation efficiency of the solar cell module at a high level, is excellent in design, and has flexibility, molding characteristics based on it, and heat resistance. It can be used very preferably as the durability based on it is compatible at an extremely high level as compared with the conventional polyethylene-based sealing material.

<Solar cell module>
One embodiment of a solar cell module using the sealing material of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the layer structure of a solar cell module using the sealing material of the present invention. The solar cell module 10 includes, from the light receiving surface side of incident light, the transparent front substrate 4, the light receiving surface side sealing material 2, the solar cell element 3, the non-light receiving surface side sealing material 1 of the present invention, and As the back side member, the heat dissipation structure 5 is laminated in order. The solar cell module 10 is characterized in that the heat dissipation performance of the entire solar cell module is sufficiently improved by disposing the sealing material 1 having excellent thermal conductivity on the non-light-receiving surface side.

  As the heat dissipating structure 5 arranged as the back side member, a heat dissipating structure having a conventionally known aluminum cast heat sink or resin heat dissipating fins can be appropriately selected and used. The solar cell module 10 having the heat dissipating structure 5 can be suitably used for solar cell power generation in general. In particular, the solar cell module 10 is used for a low-concentration solar photovoltaic device in which the temperature rise of the solar cell module is remarkable. It can be preferably used in a battery module.

  The solar cell module 10 is formed by sequentially laminating, for example, members composed of the transparent front substrate 4, the light-receiving surface side sealing material 2, the solar cell element 3, and the non-light-receiving surface side sealing material 1 of the present invention. Then, it is integrated by vacuum suction or the like, and then the above members are integrally molded by a molding method such as a lamination method, and further, the heat dissipating structure 5 is installed in the integrated laminate. be able to.

  In the solar cell module 10 of the present invention, conventionally known materials can be used for the members other than the non-light-receiving surface side sealing material 1 without particular limitation. Moreover, the solar cell module 10 of this invention may also contain members other than the said member. In addition, the sealing material of this invention is applicable not only to a single crystal type but to all other solar cell modules.

  In addition, in addition to said structure, the solar cell module which has further arrange | positioned the light reflection board can be mentioned as other preferable embodiment of the solar cell module using the sealing material of this invention. More specifically, incident light is efficiently condensed at a predetermined distance from the solar cell element and in the vicinity of any outermost surface of the solar cell module, and extremely strong light is applied to the solar cell element. A so-called concentrating solar cell module of a type in which a light reflecting plate such as a concave mirror that can guide light is disposed can be exemplified. In general, this type of solar cell module is often assumed to be used in a specially high temperature environment such as a desert area, and the solar cell module requires particularly excellent heat dissipation. The sealing material of the invention can be used very preferably.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

<Manufacture of sealing material>
A sealing material composition having the composition shown in Table 1 below (the units of numerical values other than thermal conductivity and film thickness in Table 1 are all mass%) was mixed to obtain a blend for a single layer. The above blend is used for a solar cell module which is a single layer resin sheet having a thickness of 200 μm 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 forming machine having a T die having a width of 200 mm. The sealing material was produced (Examples 1-3, Comparative Examples 1-4).

  Moreover, the sealing material sheet | seat which is a multilayer sheet | seat of the 3 layer structure formed by laminating | stacking each of those single layer resin sheets, and laminating | stacking the outermost layer on the both surfaces was produced (Examples 4-5). The total thickness of each sealing material in Example 4 and the thickness ratio of each layer were set to a total thickness of 200 μm, an intermediate layer thickness of 150 μm, and both outermost layer thicknesses of 25 μm. The total thickness of each sealing material in Example 5 and the thickness ratio of each layer were set to a total thickness of 200 μm, an intermediate layer thickness of 170 μm, and both outermost layer thicknesses of 15 μm. In addition, it shows in Table 2 about the composition ratio in the composition ratio in single layer bulk conversion of the sealing material of Example 4 and 5. FIG.

The following raw materials were used as the sealing material composition raw material.
(Base resin (A))
Base resin A1 (indicated as “A1” in Table 1): density 0.880 g / cm ³ , metallocene linear low density polyethylene (M-LLDPE) at 190 ° C. and MFR 3.5 g / 10 min
Base resin A2 (denoted as “A2” in Table 1): density 0.905 g / cm ³ , metallocene linear low-density polyethylene (M-LLDPE) at 190 ° C. and MFR 3.5 g / 10 min
(Thermal conductive resin (B))
Thermally conductive resin B1 (indicated as “B1” in Table 1): high density polyethylene (HDPE) having a density of 0.963 g / cm ³ and MFR at 190 ° C. of 7.0 g / 10 min.
Thermally conductive resin B2 (denoted as “B2” in Table 1): density 0.924 g / cm ³ , high density polyethylene (HDPE) with MFR at 230 ° C. of 2.1 g / 10 min
(Thermal conductive inorganic particles (C))
Titanium oxide T1 (indicated as “T1” in Table 1): Titanium oxide having an average particle diameter of 0.3 μm has a density of 0.900 g / cm ³ and an MFR at 190 ° C. of 3.5 g / 10 min. 60 parts by mass was mixed with 40 parts by mass of metallocene-based linear low-density polyethylene (M-LLDPE), and melted and kneaded at 200 ° C. to form a pellet. The thermal conductivity of this titanium oxide was 5.12 W / mK.

<Evaluation Example 1>
About the sealing material for solar cell modules of the Example produced by said method and a comparative example, the heat conductivity was measured with the following method, respectively. The results are shown in Table 1.
[Measurement method of thermal conductivity]
In accordance with ISO 22007-2, the thermal conductivity in the thickness direction of the sheet was measured using “TPS-2500S (manufactured by Kyoto Electronics Co., Ltd.)” as a measuring instrument.

<Evaluation Example 2>
About the sealing material for the solar cell modules of the Example produced by said method and a comparative example, film forming property was evaluated. The film forming property was evaluated by visually observing the embodiments of the sealing materials of Examples and Comparative Examples in the manufacturing process of the sealing material. As shown in Table 1, no particular problem on film formation was observed except for Comparative Example 1, but Comparative Example 1 containing 40% by mass of inorganic particles in the encapsulant composition was observed. In the film formation, it was observed that titanium oxide aggregated and clogging occurred in the filter in the extruder.

<Manufacture of solar cell modules>
Each solar cell module sample for evaluation of an Example and a comparative example was manufactured using each sealing material sheet of said Example and a comparative example, and the following back surface protection sheet. 180 mm □, 3.2 mm thick white plate semi-tempered glass (manufactured by AGC Fabricec Co., Ltd .: 3KWE33), light receiving surface side sealing material (density 0.882 g / cm ³ M-LLDPE resin sheet thickness 450 μm ), Wire-connected 5 inch single crystal solar cell element, tape-type temperature sensor (manufactured by Anri Keiki Co., Ltd .: ST-14K-060-GW1-ANP), non-light-receiving surface side sealing material example, comparative example Each of the sealing material sheets and the back surface protection sheet (polyethylene terephthalate (PET): thickness 188 μm) are laminated in this order, and are subjected to vacuum heating laminating treatment under the following laminating conditions. A solar cell module evaluation sample was obtained.
(Lamination condition) Vacuum drawing: 5.0 minutes
Pressurization (0 kPa to 100 kPa): 1.0 minute
Pressure holding (100 kPa): 10.0 minutes
Temperature 165 ° C

<Evaluation Example 3>
The heat release performance of the solar cell module evaluation samples of Examples and Comparative Examples produced by the above methods was evaluated by the following test methods. The results are shown in Table 1.
[Heat dissipation test]
The heat dissipation was evaluated based on JIS C 8912. A SUS mask that irradiates pseudo-sunlight with an illuminance of 100 mW / cm ² equivalent to AM1.5G with a solar simulator (manufactured by Mitsunaga Electric Co., Ltd .: XES-155S1) and defines an effective area as 11 cm □, The sample was placed on the light receiving part side of the solar cell module evaluation sample of the comparative example, and the cell temperature was measured after 90 minutes. The change in cell temperature in each sample was measured. The temperature immediately after the test of Comparative Example 5 in which the temperature increase after 90 minutes was the largest was taken as the reference value, and the temperature difference between the temperature immediately after the test of each sample and the reference value was evaluated according to the following criteria. The results are shown in Table 1 below as “heat dissipation”. As shown in Table 1, the sealing material of the present invention exhibits excellent heat dissipation performance when its thermal conductivity is 0.35 W / mK or more, preferably 0.39 W / mK or more. I understand.
○: The temperature difference of the cell after 90 minutes is 3 ° C. or more. Δ: The temperature difference is greater than 0 ° C. and less than 3 ° C. ×: The temperature difference is 0 ° C. or less.

  From the results of Evaluation Examples 1 to 3, the encapsulant for the solar cell module of the present invention is used for heat dissipation of the solar cell module while avoiding risks and cost increase such as low adhesion due to the addition of a large amount of inorganic particles. It can be seen that this is a sealing material that can prevent a reduction in power generation efficiency of the solar cell module.

DESCRIPTION OF SYMBOLS 1 Sealing material for non-light-receiving surface side 2 Sealing material for light-receiving surface side 3 Solar cell element 4 Transparent front substrate 5 Heat radiation structure 10 Solar cell module

Claims (11)

A sealing material composition for a solar cell module,
Including a base resin (A), a thermally conductive resin (B), and thermally conductive inorganic particles (C),
The base resin (A) is a polyethylene resin density of less than 0.870 g / cm ³ or more 0.930 g / cm ^3, the content of the sealing material composition is 90 wt% or less than 50 wt% Because
The thermally conductive resin (B) is a thermoplastic resin having a density of 0.930 g / cm ³ or more and 0.980 g / cm ³ or less, and the content in the sealing material composition is 10% by mass or more and 50%. And
The thermally conductive inorganic particles (C) are made of an inorganic substance having a thermal conductivity of 1 W / mK or more, and the content in the sealing material composition is 6% by mass or more and 35% by mass or less. A sealing material composition.   The encapsulant composition according to claim 1, wherein the thermally conductive inorganic particles (C) are made of an inorganic material having a thermal conductivity of 5 W / mK or more.   The encapsulant composition according to claim 1, wherein the thermally conductive inorganic particles (C) are titanium oxide.   The encapsulant composition according to any one of claims 1 to 3, wherein the base resin (A) is a metallocene linear low-density polyethylene.   The encapsulant composition according to any one of claims 1 to 4, further comprising a copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer.   The sealing material for solar cell modules which is a resin film formed by melt-molding the sealing material composition in any one of Claim 1 to 5.   The sealing material according to claim 6, wherein the thermal conductivity is 0.35 W / mK or more.   The sealing material according to claim 6 or 7, which has a thickness of 100 µm to 250 µm. A multilayer film having a three-layer structure comprising an intermediate layer and an outermost layer laminated on both sides of the intermediate layer;
In composition ratio at the time of single layer bulk conversion,
The content of the polyethylene resin density of less than 0.870 g / cm ³ or more 0.930 g / cm ³ is, be more than 50% by mass to 90% by mass, density 0.930 g / cm ³ or more 0.980 g / cm ³ The sealing material according to any one of claims 6 to 8, wherein a content of the following thermoplastic resin is 10% by mass or more and 50% or less.   The solar cell module formed by arrange | positioning the sealing material in any one of Claim 6 to 9 in the non-light-receiving surface side of a solar cell element.   The solar cell module according to claim 10, wherein a heat dissipation structure is disposed on the outermost layer side on the non-light-receiving surface side of the solar cell module via the sealing material.

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