JP2020141075A - Thin-film solar battery module - Google Patents

Abstract

To reduce the risk of an insulative resin material, which ensures the electrical isolation between a thin film solar battery element and a metal wiring line in "a double-sided glass protective base-type thin-film solar battery module," suffering photodegradation and thus causing a dielectric breakdown during a long-term use in a desert area or the like.SOLUTION: A double-sided glass protective base-type thin-film solar battery module 10 comprises a metal wiring line 33 disposed on an insulative resin material 5 on a backside of a thin film solar battery element 3 serving as a non-light receiving face. The thin-film solar battery module further comprises a seal-material sheet 1 composed of a resin sheet containing a polyethylene-based resin as a base resin and having a total thickness of 600 μm or less. The resin sheet is 0% in gel fraction, and has a melting point of 80°C or more and 115°C or less in the whole layer. The seal-material sheet 1 contains a UV absorber or a white pigment.SELECTED DRAWING: Figure 1

Description

The present invention is a solar cell module (referred to as "thin film solar cell module" in the present specification) on which a thin film solar cell element is mounted, and a transparent glass substrate is arranged on both outermost surfaces. Regarding "double-sided glass protective substrate type thin-film solar cell module".

In recent years, due to growing awareness of environmental issues, solar cells have been attracting attention as a clean energy source. For the solar cell element, in addition to the crystalline silicon solar cell element manufactured by using a single crystal silicon substrate or a polycrystalline silicon substrate, an ultrathin silicon film of about 1 μm is formed on a substrate such as glass with amorphous silicon or microcrystalline silicon. There is a thin-film solar cell element produced by molding.

The thin-film solar cell element is more advantageous than the crystalline silicon solar cell element in terms of the degree of freedom in the installation location due to its light weight and the economic efficiency due to the reduction in material cost. Compared to crystalline silicon solar cells, thin-film solar cell elements are less likely to lose conversion efficiency under high-temperature conditions, and crystalline silicon is also suitable as a solar cell installed in high-temperature areas such as desert areas. Has an advantage over solar cells. Due to these various advantages, in recent years, the demand for thin-film solar cell modules using thin-film solar cell elements has tended to expand worldwide.

The general layer structure of the thin-film solar cell module, whose demand has been increasing in recent years, is as shown in FIG. 1, and is a transparent front glass substrate 2, a thin-film solar cell element 3, a sealing material sheet 1, and a transparent back glass. The basic layer structure is a structure in which the substrate 4 and the substrate 4 are sequentially laminated. Further, in the thin film solar cell module 10, in many cases, as also shown in FIG. 1, a metal wiring 33 for collecting electricity and a thin film system are arranged across the back surface side of the thin film solar cell element 3. By interposing an insulating resin material 5 made of a polyester-based resin tape or the like between the electrodes of the solar cell element 3, the insulation between the two is maintained.

In the thin-film solar cell module 10 having the layer structure shown in FIG. 1, the sealing material sheet 1 that seals the thin-film solar cell elements 3 laminated on the transparent front glass substrate has heat resistance and good molding characteristics. Is required at a high level in a well-balanced manner. As an encapsulant sheet that can meet such demands, a thermoplastic polyethylene encapsulant sheet in which the core layer (intermediate layer) of the multi-layered sheet having a three-layer structure is made of a resin having a relatively high density and low elasticity. (Refer to Patent Document 1), or a multilayer sheet having the above configuration, in which the melting point of the core layer is set to a certain level or higher, and the skin layer contains a silane-modified polyethylene-based resin in a predetermined amount range, which is a thermoplastic polyethylene seal. Development of various encapsulant sheets whose composition and composition are optimized assuming use in thin-film solar cell modules, such as stop material sheets (see Patent Document 2), is in progress.

On the other hand, in many cases, the thin-film solar cell module has transparent glass substrates (transparent front glass substrate 2 and transparent back glass substrate 4) arranged on both outermost surfaces as described above. Such a layer structure allows moisture to enter the module, for example, as compared with a structure in which the protective sheet on the back side, which is often seen in many solar cell modules other than the thin film solar cell module, is made of a resin sheet. It has a great advantage in the water vapor barrier property to prevent. For this reason, it has been conventionally considered that such a module layer structure is an excellent layer structure that can easily secure long-term durability even if it is assumed to be installed in a high temperature area such as a desert area. ..

However, as described above, when the thin-film solar cell module is installed in a desert area or the like by taking advantage of the thin-film solar cell element, the environment is such that intense reflected light is incident from the back surface side of the module. It will be exposed for a long period of time. Therefore, even if the above-mentioned insulating resin material 5 is sufficiently prevented from being deteriorated by hydrolysis by the protective substrate made of glass, it is exposed to the intense reflected light that penetrates through the protective substrate made of glass for a long period of time. When exposed to light, photodegradation may occur, resulting in dielectric breakdown. Reducing this risk has come to be required to be newly addressed, in particular, as a new technical issue included in the "double-sided glass protective substrate type thin-film solar cell module".

Japanese Unexamined Patent Publication No. 2017-118074 JP-A-2018-60837

The present invention has been made in view of the above circumstances, and is an insulating resin that guarantees insulation between a thin film solar cell element and a metal wiring in a "double-sided glass protective substrate type thin film solar cell module". An object of the present invention is to reduce the risk that the material causes light deterioration and dielectric breakdown during long-term use in a desert area or the like.

As a result of diligent studies, the present inventors have optimized the composition and composition of the resin sheet assuming use in a thin-film solar cell module, and in the thin-film solar cell module, the solar cell element is used. However, they have found that the above problems can be solved by containing an ultraviolet absorber or a white pigment in the encapsulant sheet arranged closer to the non-light receiving surface side, and have completed the present invention. .. More specifically, the present invention provides the following.

(1) A transparent front glass substrate, a thin-film solar cell element laminated on the back surface of the transparent front glass substrate, a sealing material sheet, and a transparent back glass substrate are sequentially laminated. The thin-film solar cell module is a thin-film solar cell module in which metal wiring is arranged on the back side, which is the non-light receiving surface of the thin-film solar cell element, with an insulating resin material in between, and the sealing material sheet is polyethylene. A single-layer or multi-layer resin sheet using a based resin as a base resin and having a total thickness of 600 μm or less. The resin sheet has a gel content of 0% and a melting point of 55 ° C. or higher and 115 ° C. in all layers. A thin-film solar cell module, wherein the encapsulant sheet contains an ultraviolet absorber or a white pigment.

(2) The thin-film solar cell module according to (1), wherein the sealing material sheet does not contain an ultraviolet absorber.

(3) The thin-film solar cell module according to (1), wherein the encapsulant sheet does not contain a white pigment.

(4) The encapsulant sheet is a multilayer resin sheet containing a core layer and skin layers arranged on both outermost surfaces, and the melting point of the core layer is 90 ° C. or higher and 115 ° C. or lower. The thin-film solar cell module according to any one of (1) to (3), wherein the skin layer has a melting point of 55 ° C. or higher and 70 ° C. or lower.

(5) The core layer has a density of the base resin and 0.900 g / cm ³ or more 0.930 g / cm ³ or less of the polyethylene resin, the skin layer has a density, 0.870 g / cm ³ or more zero. The thin film-based solar cell module according to (4), which uses a polyethylene-based resin of 899 g / cm ³ or less as a base resin.

(6) The thin-film solar cell module according to any one of (1) to (5), wherein the insulating resin material is polyethylene terephthalate.

According to the present invention, in the "double-sided glass protective substrate type thin film solar cell module", the insulating resin material that guarantees the insulation between the thin film solar cell element and the metal wiring is used for a long time in a desert area or the like. It is possible to reduce the risk of dielectric breakdown due to photodeterioration during the period.

It is sectional drawing which shows typically the layer structure of the thin film type solar cell module of this invention. It is sectional drawing which shows typically an example of the layer structure of the sealing material sheet which can be suitably used for the thin film type solar cell module of this invention.

<Double-sided glass protective substrate type thin-film solar cell module>
FIG. 1 is a cross-sectional view schematically showing the layer structure of the thin-film solar cell module 10 of the present invention. In the thin-film solar cell module 10, a thin film formed in a thin film form on the surface of the transparent front glass substrate 2 and the back surface side (non-light receiving surface side) of the transparent front glass substrate 2 from the light receiving surface side of the incident light L. The system solar cell element 3, the sealing material sheet 1, and the transparent back glass substrate 4 are laminated in this order.

Further, in the thin film solar cell module 10, a metal wiring 33 is arranged on the back surface side (non-light receiving surface side) of the thin film solar cell element 3 with an insulating resin material 5 interposed therebetween.

Further, the double-sided glass protective substrate type thin-film solar cell module 10 sandwiched between glass protective substrates has a so-called frameless structure in which a metal protective frame installed surrounding the side surface of the module is eliminated. Often done. Including this case, an edge seal 6 made of butyl rubber or the like may be arranged on the side surface of the thin film solar cell module 10 as a member for sealing the side surface of the module in the manner shown in FIG. It is common.

Here, in the thin-film solar cell module 10, as shown in FIG. 1, unevenness due to the insulating resin material 5, the metal wiring 33, or the like exists on the surface of the thin-film solar cell element 3 on the non-light receiving surface side. When a conventional encapsulant sheet using a polyethylene-based resin as a base resin is used, if the required heat resistance is to be ensured by cross-linking or simply increasing the density, the embedding property for this unevenness (hereinafter, "molding characteristics"). There is a problem that voids may be formed around the unevenness due to the lack of (). The encapsulant sheet 1 constituting the thin-film solar cell module 10 of the present invention is sufficiently molded when the thickness of the unevenness is 50% or more and 90% or less of the thickness of the encapsulant sheet 1. The composition of the base resin is the same as that of the encapsulant sheet (see Patent Documents 1 and 2) jointly developed by the present inventors as being capable of exhibiting the characteristics, and similarly, sufficient molding characteristics are exhibited. It can be done.

The thin-film solar cell module 10 is obtained by sequentially laminating each component including a transparent front glass substrate 2, a thin-film solar cell element 3, a sealing material sheet 1, a transparent back glass substrate 4, and the like, and then vacuum suction or the like. Then, by a molding method such as a lamination method, the above-mentioned members can be heat-bonded and molded as an integrally molded body.

[Transparent front glass substrate, transparent back glass substrate]
In the double-sided glass protective substrate type thin-film solar cell module 10, the transparent front glass substrate 2 and the transparent back glass substrate 4 are both made of a glass plate material. As the protective substrate made of glass, various transparent glass plate materials that have been mainly used as the front protective substrate in various solar cell modules can be used without particular limitation.

[Thin film solar cell element]
As shown in FIG. 1, the thin-film solar cell element 3 is formed on the power generation layer 30, the transparent electrode 31 formed on the light receiving surface side of the power generation layer 30, and the non-light receiving surface side of the power generation layer 30. It is composed of a metal electrode 32. In the thin film solar cell module 10, the insulation between the metal electrode 32 and the metal wiring 33 is maintained by the insulating resin material 5.

As the thin-film solar cell element 3, various thin-film elements such as amorphous silicon, microcrystalline silicon, and a thin-film solar cell (CIGS) using a chalcopyrite-based compound can be appropriately selected. .. However, among these, compound-based thin-film solar cell elements such as CdTe, CIGS, and perovskite can be particularly preferably used from the viewpoint of power generation efficiency, assuming use in a high temperature zone.

[Insulating resin material]
As shown in FIG. 1, as the insulating resin material 5 of the present invention, a double-sided adhesive insulating resin tape in which adhesive layers are formed on both sides of an insulating resin base material made of an insulating resin base material is preferably used. be able to.

In thin-film solar cell module 10, the level of insulation required for the insulating resin material 5 is generally, the volume resistivity of the resin base material forming the insulating resin material 5, 1.0 × 10 ⁹ Omega -Cm or more, preferably 1.0 x 10 ¹¹ Ω-cm or more. The insulating resin material 5 may be a resin base material that can satisfy the above-mentioned requirements for insulating properties.

Further, since the thin-film solar cell module 10 is expected to be used outdoors in a harsh high temperature environment for a long period of time, it is preferably a resin having excellent long-term durability. For example, specifically, a resin base material using a polyester resin such as polyethylene terephthalate (PET) as a base resin can be preferably used as the insulating resin material 5.

The thickness of the insulating resin material 5 is generally 20 μm or more and 250 μm or less on the premise that the thickness is such that the insulating property satisfying the safety eligibility of the thin-film solar cell module specified in IEC61730-2 can be guaranteed. It is preferable that it is 25 μm or more and 200 μm or less.

[Encapsulant sheet]
The encapsulant sheet constituting the thin-film solar cell module 10 of the present invention is a resin sheet using a polyethylene resin as a base resin.

(Layer structure / thickness)
Further, the sealing material sheet constituting the thin-film solar cell module 10 may have a single-layer structure, but as described in detail below, a multi-layered seal in which the melting point is individually optimized for each layer. It is preferably the stop material sheet 1. In any of the layer configurations, the total thickness may be 250 μm or more and 600 μm or less, and preferably 350 μm or more and 500 μm or less.

(Basic composition)
Further, the sealing material sheet constituting the thin-film solar cell module 10 preferably has a melting point of 80 ° C. or higher and 115 ° C. or lower in all layers. The more preferable melting point range for each layer when the sealing material sheet is a multilayer sheet will be described later.

The encapsulant sheet constituting the thin-film solar cell module 10 is a thermoplastic resin sheet that does not require a cross-linking treatment step at the time of manufacture. Therefore, the gel fraction of the encapsulant sheet is 0%.

The "gel fraction (%)" in the present specification refers to 0.1 g of a sealing material in a resin mesh, extracted with toluene at 120 ° C. for 24 hours, taken out together with the resin mesh, dried, and weighed. The mass before and after extraction was compared, the mass% of the residual insoluble matter was measured, and this was used as the gel fraction. The gel fraction of 0% means that the residual insoluble matter is substantially 0 and the cross-linking reaction of the encapsulant composition is not substantially started. More specifically, "gel fraction 0%" means that the residual insoluble matter is not present at all, and the mass% of the residual insoluble matter measured by a precision balance is less than 0.05% by mass. Suppose to say. 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 mixture in the resin component in advance, these It is possible to calculate the gel fraction that should be originally obtained for the residual insoluble matter derived from the resin component excluding the mixture.

The encapsulant sheet constituting the thin-film solar cell module 10 contains a white pigment or an ultraviolet absorber.

As the white pigment contained in the encapsulant sheet, known white pigments such as titanium oxide, calcium carbonate and barium sulfate can be appropriately selected and used. Among them, titanium oxide can be particularly preferably used from the viewpoint of versatility.

When a white pigment is selected and contained in the encapsulant sheet constituting the thin-film solar cell module 10 from the above additives, the content of the white pigment in the encapsulant sheet is 0. It is preferably 3% by mass or more and 6% by mass or less, and more preferably 0.5% by mass or more and 5% by mass or less.

When the content of the white pigment in the resin component of the sealing material sheet constituting the thin-film solar cell module 10 is 0.3% by mass or more, the risk of photodeterioration of the insulating resin material 5 is sufficiently reduced. Can be done.

On the other hand, when the content of the white pigment in the resin component of the encapsulant sheet constituting the thin-film solar cell module 10 is 6% by mass or less, the encapsulant sheet due to reduced film forming property, bleed-out, or the like. It is possible to sufficiently avoid a decrease in the adhesion of the.

Further, since the sealing material sheet constituting the thin-film solar cell module 10 has the melting point individually optimized for each layer in the manner described later, both heat resistance and molding characteristics are compatible at a high level. In the case of the multi-layered resin sheet (encapsulating material sheet 1), it is particularly preferable to keep the content of the white pigment in the resin component of the encapsulant sheet 1 to a small amount of 5% by mass or less. Thereby, the excellent molding characteristics of such a sealing material sheet can be maintained at the above-mentioned high level with higher accuracy.

In the thin-film solar cell module 10 shown in FIG. 1, the light reflectivity of the encapsulant sheet is conventionally adjusted to adjust the content of the white pigment to a low content range different from the conventional one as described above. In order to reflect the light entering from the side toward the solar cell element, it is not necessary to have a high reflectance as high as the white encapsulant sheet arranged on the non-light receiving surface side of the solar cell element. The composition of the thin-film solar cell module 10 is such that the reflected light incident from the back surface side has a composition that gives priority to maintaining the molding characteristics within a range in which the risk of light deterioration of the insulating resin material 5 can be sufficiently reduced. This is due to the original ingenuity of the present inventors, who focused on being beneficial for total quality improvement.

As the ultraviolet absorber contained in the sealing material sheet constituting the thin-film solar cell module 10, a known ultraviolet absorber such as a benzophenone-based ultraviolet absorber, a benzotriazole-based purple, or a triazine-based ultraviolet absorber is appropriately selected. Can be used.

When the sealing material sheet constituting the thin-film solar cell module 10 contains an ultraviolet absorber, the content of the ultraviolet absorber in the resin component of the sealing material sheet is 0.05% by mass or more 1 It is preferably 5.5% by mass or less. When the content of the ultraviolet absorber in the resin component of the sealing material sheet is 0.05% by mass or more, the risk of photodegradation of the insulating resin material can be sufficiently reduced. On the other hand, if the content exceeds 1.5% by mass, the problem of bleed-out of the ultraviolet absorber tends to become apparent, which is not preferable. In addition, the "ultraviolet absorber" in the present specification absorbs harmful ultraviolet rays in sunlight and converts them into harmless thermal energy in the molecule, and starts photodegradation of the material resin of the encapsulant sheet. It refers to an additive that can prevent the active species from being excited.

(Multi-layered resin sheet with excellent heat resistance and molding characteristics)
The encapsulant sheet constituting the thin-film solar cell module 10 may be a single-layer sheet as long as the above requirements are satisfied, but as in the encapsulant sheet 1 shown in FIG. 2, the core layer 11 and both are the most. It is more preferable that the resin sheet has a multi-layer structure having the skin layer 12 arranged on the surface.

As shown in FIG. 2, the sealing material sheet 1 is a multi-layered resin sheet having a core layer 11 and skin layers 12 arranged on both outermost surfaces. Hereinafter, the details of the sealing material sheet 1 which is a multi-layered resin sheet optimized as the sealing material sheet constituting the thin-film solar cell module 10 will be described.

In the present specification, the skin layer refers to a layer arranged on both outermost surfaces of the multi-layered resin sheet, and the core layer refers to an inner layer other than the above-mentioned skin layer in the multi-layered resin sheet. Say. The core layer itself may have a multi-layered internal structure.

The base resin of the core layer 11 constituting the encapsulant sheet 1 is a low density polyethylene resin (LDPE), a linear low density polyethylene resin (LLDPE), or a metallocene linear low density polyethylene resin (M-). LLDPE) is preferable. In the present specification, the "base resin" refers to the resin having the largest content ratio among the resin components of the resin layer in the resin layer containing the base resin.

The base resin of the skin layer 12 constituting the sealing material sheet 1 is a low-density polyethylene-based resin (LDPE), a linear low-density polyethylene-based resin (LLDPE), or a metallocene-based linear low-density resin, similarly to the core layer 11. It is preferably a density polyethylene resin (M-LLDPE). Above all, the base resin of the skin layer 12 is more preferably a metallocene-based linear low-density polyethylene-based resin (M-LLDPE) from the viewpoint of molding characteristics.

As described above, the multi-layered encapsulant sheet 1 constituting the thin-film solar cell module 10 contains a white pigment or an ultraviolet absorber. Of these, when a white pigment is contained, it is preferable that the white pigment is contained only in the core layer 11. As a result, it is possible to sufficiently reduce the risk of photodegradation of the insulating resin material while more reliably avoiding a decrease in film-forming property and a decrease in adhesion of the sealing material sheet due to bleed-out or the like.

When the sealing material sheet 1 contains an ultraviolet absorber, it is preferable that the ultraviolet absorber is contained only in the skin layer 12 and the core layer 11 on the transparent back glass substrate 4, and the transparent back glass substrate 4 side. It is more preferable to contain it only in the skin layer 12 of the above. As a result, the ultraviolet absorber deteriorates due to direct contact with the thin-film solar cell element 3, and further wraps around to the light receiving surface side to absorb a part of ultraviolet light having a wavelength that can contribute to power generation. You can avoid that.

As described above, the total thickness of the encapsulant sheet 1 including the core layer 11 and the skin layer 12 is 250 μm or more and 600 μm or less, preferably 350 μm or more and 500 μm or less. If the total thickness is less than 250 μm, the impact cannot be sufficiently mitigated, but if the total thickness is 250 μm or more, the molding characteristics and heat resistance of the encapsulant sheet 1 are maintained at sufficiently preferable levels. be able to. If the total thickness exceeds 600 μm, it is difficult to obtain the effect of further improving the impact mitigation effect, it is not possible to meet the request for thinning the thin-film solar cell module 10, and it is uneconomical. Not preferable.

The thickness of the core layer 11 in the encapsulant sheet 1 is preferably 200 μm or more and 400 μm or less, and more preferably 250 μm or more and 350 μm or less. The thickness of each layer of the skin layer 12 is preferably 30 μm or more and 100 μm or less, and more preferably 35 μm or more and 80 μm or less. The total thickness of the two skin layers 12 laminated on both sides of the core layer is 1/20 or more and 1/3 or less of the total thickness of the encapsulant sheet 1, preferably 1/15. It is preferably 1/4 or less. By specifying the thickness of each layer of the encapsulant sheet 1 in such a range, the heat resistance and the molding characteristics of the encapsulant sheet 1 can be maintained in a good range.

The melting point of the core layer 11 of the encapsulant sheet 1 is preferably 90 ° C. or higher and 115 ° C. or lower, and more preferably 95 ° C. or higher and 110 ° C. or lower. When the melting point of the core layer 11 is 90 ° C. or higher, the sealing material sheet 1 can be provided with the necessary heat resistance. Further, the melting point of the core layer is 115 ° C. in relation to the heating conditions at the time of melt molding for forming a sheet as a sealing material sheet and at the time of thermal lamination treatment for integration as a thin film solar cell module. The melting point of the core layer 11 is more preferably 110 ° C. or lower in order to sufficiently enhance the molding characteristics of the sealing material sheet 1.

As described above, the melting point of the core layer 11 is preferably 90 ° C. or higher and 115 ° C. or lower, but the core layer is appropriately mixed with polyethylene resins having different melting points as the sealing material composition for forming the core layer 11. It can also be used as a sealing material composition for forming 11. For example, according to a resin composition in which three types of polyethylene resins having melting points of 60 ° C., 90 ° C., and 105 ° C. are mixed by 15 parts by mass, 8 parts by mass, and 82 parts by mass, the melting point of the core layer is 97. Can be ° C. Then, a compounding example of such a material resin can be exemplified as a preferable resin compounding example of the sealing material composition for the core layer.

The melting point of the skin layer 12 of the sealing material sheet 1 is preferably 55 ° C. or higher and 70 ° C. or lower, and more preferably 60 ° C. or higher and 65 ° C. or lower. When the melting point of the skin layer 12 is 55 ° C. or higher, the sealing material sheet 1 can be provided with the necessary heat resistance. Further, when the melting point of the skin layer 12 is 70 ° C. or lower, the molding characteristics of the encapsulant sheet at the time of integration as a thin film solar cell module can be maintained in a preferable range.

As described above, the melting point of the skin layer 12 is preferably 55 ° C. or higher and 70 ° C. or lower, but polyethylene resins having different melting points may be appropriately mixed and used as a sealing material composition for forming the skin layer 12. it can. For example, according to a resin composition in which two types of polyethylene resins having melting points of 60 ° C. and 90 ° C. are mixed by 85 parts by mass and 20 parts by mass, respectively, the melting point of the entire skin layer can be set to 66 ° C. it can. Then, a compounding example of such a material resin can be exemplified as a preferable resin compounding example of the sealing material composition for the skin layer.

The melting point in the present specification refers to the average value of the melting points obtained by calculating from the unique melting points of each component contained in the object to be measured and their blending ratios. For example, the melting point of the encapsulant sheet or each of the resin layers constituting the encapsulant sheet according to this definition can be obtained by measuring by differential scanning calorimetry (DSC). When there are a plurality of valley peaks on the DSC curve, the melting point indicated by the peak having the largest peak area can be used as the melting point of the encapsulant sheet or each of the resin layers. Further, as another method for specifying the melting point according to the above definition from the encapsulant sheet, when the measured coefficient of linear expansion measured according to JIS K7179 is expressed as a function of the resin temperature, the coefficient of linear expansion decreases from the increase. It is also possible to obtain an approximate method by measuring the linear expansion peak temperature, which is the temperature at the maximum value at the time of turning to. According to this method, the melting point according to the above definition can be specified from a finished product such as a sealing material sheet.

Further, the core layer 11 of sealing material sheet 1, density of 0.900 g / cm ³ or more 0.930 g / cm ³ or less, more preferably 0.910 g / cm ³ or more 0.920 g / cm ³ or less of the polyethylene resin Is preferably used as the base resin. By setting the density of the base resin forming the core layer 11 within the above range, the encapsulant sheet 1 using the thermoplastic resin can be provided with heat resistance and molding characteristics at a high level in a well-balanced manner.

Further, the skin layer of the sealing material sheet 1, density of 0.870 g / cm ³ or more 0.899 g / cm ³ or less, more preferably 0.880 g / cm ³ or more 0.890 g / cm ³ or less of the polyethylene resin It is preferable to use a base resin. By setting the density of the base resin forming the skin layer 12 in the above range, the adhesion of the sealing material sheet 1 can be maintained in a preferable range.

The MFR of the encapsulant sheet 1 having a three-layer structure including the core layer 11 and the skin layer 12 is preferably 3.0 g / 10 min or more and less than 5.0 g / 10 min on average for all layers. More preferably, it is 10 min or more and less than 3.8 g / 10 min. When the MFR of the encapsulant sheet 1 is less than 5.0 g / 10 min, the required heat resistance of the encapsulant sheet 1 can be provided, and the MFR is 3.0 g / 10 min or more. Therefore, the sealing material sheet 1 can be provided with excellent molding characteristics.

The MFR in the present specification is a value obtained by the following method unless otherwise specified.
MFR (g / 10min): 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 from an opening (nozzle) provided at the bottom of the container was measured per 10 minutes. .. The test machine used an extruded plastometer, and the extruded load was 2.16 kg.
The MFR of the multi-layer encapsulant sheet was measured by the above treatment while all the layers were integrally laminated, and the obtained measured value was used as the MFR value of the multi-layer encapsulant sheet. ..

A "silane-modified polyethylene-based resin" obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer on the core layer and the skin layer, particularly the skin layer, which constitute the encapsulant sheet 1. Is more preferably contained in each layer in a certain amount, if necessary. The silane-modified polyethylene-based resin is obtained by graft-polymerizing a linear low-density polyethylene-based resin (LLDPE) or the like as a main chain with an ethylenically unsaturated silane compound as a side chain. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to adhesive strength, it is possible to improve the adhesiveness of the sealing material sheet 1 to other members in the thin-film solar cell module 10. ..

The silane-modified polyethylene-based resin can be produced, for example, by the method described in JP-A-2003-46105, and by using the resin as a component of a sealing material composition forming each layer of the sealing material sheet, the resin can be produced. It has excellent strength, durability, etc., and also has excellent weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, haze resistance, and other various characteristics. Furthermore, manufacturing conditions such as heat crimping for manufacturing solar cell modules. It is possible to manufacture a thin-film solar cell module suitable for various applications with extremely excellent heat-sealing property without being affected by the above, stably and at low cost.

Further, an adhesion improver can be appropriately added to the core layer and the skin layer constituting the sealing material sheet 1, particularly the skin layer. As the adhesion improver, a known silane coupling agent can be used, but a silane coupling agent having an epoxy group (hereinafter, also referred to as "epoxy-based silane coupling agent") or a silane having a mercapto group. Couplings (hereinafter, also referred to as "mercapto-based silane coupling agents") can be particularly preferably used.

The core layer and the skin layer constituting the sealing material sheet 1 can further contain other components. It is preferable that each of these layers contains a hindered amine-based light-resistant stabilizer (HALS) as a light-resistant stabilizer. When a hindered amine-based light-resistant stabilizer is contained, the content thereof is preferably 0.001% by mass or more and 0.20% by mass or less in the resin component of the encapsulant sheet.

Further, the sealing material sheet 1 can further contain other components. For example, components such as various weather resistant master batches, various fillers, and heat stabilizers are exemplified. Although these contents vary depending on the particle shape, density, etc., it is preferably in the range of 0.001 to 5% by mass in the resin component of the encapsulant sheet. By containing an appropriate amount of these additives, it is possible to impart stable mechanical strength over a long period of time and an effect of preventing yellowing, cracking, etc. to the encapsulant composition for a solar cell module.

The encapsulant sheet 1 is formed into a sheet by a molding method usually used in a normal thermoplastic resin, that is, various molding methods such as injection molding, extrusion molding, hollow molding, compression molding, and rotary molding. As an example of the method of forming a sheet when the encapsulant sheet is a multilayer film, there is a method of forming by coextrusion with three types of melt-kneading extruders.

However, in any of the above molding methods, the melt molding temperature in the production of the encapsulant sheet 1 is the melting point of the base resin of the encapsulant composition for the core layer contained in the encapsulant composition + 30 ° C. or higher. Is preferable. Specifically, the temperature is preferably 175 ° C. to 230 ° C., and more preferably 190 ° C. to 210 ° C. Since the sealing material composition used for the sealing material sheet 1 is a thermoplastic composition that does not contain a cross-linking agent, it is not necessary to consider inconvenient control of the progress of cross-linking during melt molding. As a result, in the production of a sealing material sheet using a polyethylene-based resin as a base resin, a solution method is performed from the temperature limitation when a thermosetting type sealing material composition that requires a cross-linking treatment, which has been generally used in the past, is used. The melt molding temperature can be set in a higher temperature range in order to improve the productivity. As a result, the encapsulant sheet 1 can be manufactured with higher productivity than the conventional thermosetting encapsulant sheet.

According to the thin-film solar cell module of the present invention described above, the following effects are obtained.

(1) Conventionally, in a "double-sided glass protective substrate type thin film solar cell module", a seal is arranged so as to seal the non-light receiving surface side of the thin film solar cell element formed on the back surface of the transparent front glass substrate. No additive was added to the stop material sheet to enhance the light resistance. This is because the problem of photodegradation of the insulating resin material, which is peculiar to installation in desert areas, was not recognized. On the other hand, in the invention of (1), in the "double-sided glass protective substrate type thin film solar cell module" in which transparent glass substrates are arranged on both outermost surfaces, the use for the thin film solar cell module. It is a resin sheet whose heat resistance and molding characteristics are optimized on the assumption that the thin film type solar cell module is a sealing material sheet arranged closer to the non-light receiving surface side than the solar cell element. , An ultraviolet absorber or a white pigment was added. As a result, by simply adding one of the above light-resistant agents to the encapsulant composition, the "double-sided glass protective substrate type thin-film solar cell module" can be installed in the desert area without changing the other basic configurations. It is possible to suppress photodegradation of the insulating resin material, which is a problem peculiar to the use in such cases.

In the invention of (2), the encapsulant sheet is configured to contain only a white pigment without containing an ultraviolet absorber. According to this, while avoiding the above-mentioned problem included in the conventional "double-sided glass protective substrate type thin-film solar cell module", the ground inside the module in the thin-film solar cell module described in (1). By suppressing the intrusion of reflected light from the side, it is possible to suppress the temperature rise in the module and reduce the risk of a decrease in power generation efficiency. Further, the design can be improved by giving a white appearance.

In the invention of (3), the encapsulant sheet is configured to contain only an ultraviolet absorber without containing a white pigment. According to this, the effect of the thin-film solar cell module described in (1) can be enjoyed without changing the appearance of the conventional "double-sided glass protective substrate type thin-film solar cell module".

In the invention of (4), the encapsulant sheet constituting the "double-sided glass protective substrate type thin film solar cell module" is formed into a multilayer sheet having a skin layer-core layer-skin layer structure, and the melting point of each layer is set. Optimized for a specific range that can combine molding characteristics and heat resistance at a high level. As a result, the reliability of the long-term durability of the solar cell module can be further improved while enjoying the above-mentioned effects in the invention of any one of (1) to (3).

In the invention of (5), the encapsulant sheet constituting the "double-sided glass protective substrate type thin-film solar cell module" is formed into a multi-layer sheet having a skin layer-core layer-skin layer structure to form each layer. The density of the base resin has been optimized to a specific range that can combine molding characteristics and heat resistance at a high level. As a result, the reliability of the long-term durability of the solar cell module can be further improved while enjoying the above-mentioned effects in the invention of any one of (1) to (3).

In the invention of (6), when the insulating resin material is composed of highly versatile polyethylene terephthalate, the overall configuration of the thin-film solar cell module is specified. In this case, the peculiar effect of the present invention of preventing photodegradation of the insulating resin material can be widely enjoyed as the most significant effect.

Based on the above, according to the present invention, in the "double-sided glass protective substrate type thin film solar cell module", the insulating resin material that guarantees the insulation between the thin film solar cell element and the metal wiring is a desert area or the like. It can be seen that the risk of light deterioration and dielectric breakdown during long-term use in the above can be sufficiently reduced.

1 Encapsulant sheet 11 Core layer 12 Skin layer 2 Transparent front glass substrate 3 Thin-film solar cell element 30 Power generation layer 31 Transparent electrode 32 Metal electrode 33 Metal wiring 4 Transparent back front glass substrate 5 Insulation resin material 6 Edge seal 10 Thin film system Solar cell module

Claims (6)

With a transparent front glass substrate,
A thin-film solar cell element laminated on the back surface of the transparent front glass substrate, and
Encapsulant sheet and
The transparent back glass substrate and the transparent back glass substrate are sequentially laminated,
A metal wiring is arranged on the back side, which is a non-light receiving surface of the thin-film solar cell element, with an insulating resin material in between.
It is a thin-film solar cell module.
The encapsulant sheet is a single-layer or multi-layer resin sheet using a polyethylene-based resin as a base resin and having a total thickness of 600 μm or less, and the resin sheet has a gel fraction of 0% and all layers. The melting point in is 55 ° C or higher and 115 ° C or lower.
The encapsulant sheet contains an ultraviolet absorber or a white pigment.
Thin-film solar cell module. The thin-film solar cell module according to claim 1, wherein the sealing material sheet does not contain an ultraviolet absorber. The thin-film solar cell module according to claim 1, wherein the encapsulant sheet does not contain a white pigment. The sealing material sheet
A multi-layered resin sheet containing a core layer and skin layers arranged on both outermost surfaces.
The melting point of the core layer is 90 ° C. or higher and 115 ° C. or lower.
The melting point of the skin layer is 55 ° C. or higher and 70 ° C. or lower.
The thin-film solar cell module according to any one of claims 1 to 3. The core layer has a density of a 0.900 g / cm ³ or more 0.930 g / cm ³ or less of the polyethylene resin as a base resin,
The skin layer has a density of a 0.870 g / cm ³ or more 0.899 g / cm ³ or less of the polyethylene resin as a base resin,
The thin-film solar cell module according to claim 4. The thin-film solar cell module according to any one of claims 1 to 5, wherein the insulating resin material is polyethylene terephthalate.

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