JP4967414B2 - Solar cell back surface protection sheet and solar cell module - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a back surface protective sheet for a solar cell, which has excellent required properties, is inexpensive, and has excellent design properties, and a solar cell module using the same.

  In recent years, various efforts have been made to suppress carbon dioxide emissions while interest from various countries both inside and outside Japan has increased. Increasing fossil fuel consumption leads to an increase in atmospheric carbon dioxide, and the greenhouse effect raises the Earth's temperature, significantly affecting the global environment. Various studies have been conducted on alternative energy to fossil fuels, but there is an increasing expectation for photovoltaic power generation, which is a clean energy source. A solar cell used for photovoltaic power generation constitutes the heart of a photovoltaic power generation system that directly converts solar energy into electricity, and is made of a semiconductor. As the structure, a single solar cell element is not used as it is, and generally several to several tens of solar cell elements are wired in series and in parallel to protect the element over a long period of time. Therefore, various packaging is performed and unitized. A unit built in this package is called a solar cell module. Generally, the surface that is exposed to sunlight is covered with glass, the gap is filled with a filler made of thermoplastic, and the back is made of a heat- and weather-resistant plastic material. The structure is protected by a white sheet. The reason for using the white sheet is to reflect light and increase the power generation effect.

  Since these solar cell modules are used outdoors, sufficient durability and weather resistance are required in the materials used and their configurations. In particular, the back surface protection sheet is required to be white and have a weather resistance and a low water vapor transmission rate. This is because moisture permeation causes the filler in the unit to peel off, causing corrosion of the wiring and adversely affecting the module output itself.

Conventionally, as the back surface protection sheet for solar cells, a back surface protection sheet having a laminated structure in which an aluminum foil is sandwiched from both sides with a white fluorine-based film has been often used. However, this fluorine-based film has low mechanical strength and is softened by heat of 140 ° C. to 150 ° C. hot press applied at the time of making the solar cell module, and the projection of the solar cell element electrode portion penetrates the filler layer, Furthermore, by penetrating the fluorine-based film on the inner surface constituting the back surface protection sheet and contacting the aluminum foil in the back surface protection sheet, the solar cell element and the aluminum foil are short-circuited to adversely affect the battery performance. At the same time, it is expensive and is an obstacle in terms of reducing the price of solar cell modules. In order to improve these problems, a solar cell back surface sealing film made of a laminate in which a gas barrier layer is laminated on one side of a white biaxially stretched polyethylene terephthalate film layer made of a special polymer has been proposed (for example, Patent Documents). 1).
JP 2002-26354 A

  However, the proposed solar cell back surface sealing film has the disadvantages that the biaxially stretched polyethylene terephthalate film used is entirely white, has poor design, and is difficult to differentiate from other products. .

  The subject of this invention is providing the solar cell module using the back surface protection sheet for solar cells which has various characteristics, such as a weather resistance and moisture resistance, and has the outstanding designability.

  In the invention according to claim 1 of the present invention, a colored layer and a weather resistant resin layer are formed on the vapor-deposited thin film layer surface of the gas barrier laminated film layer formed by laminating at least one inorganic oxide vapor-deposited thin film layer on one surface of the base material layer. In the back protective sheet for solar cells, which is sequentially laminated, the colored layer and the weather-resistant resin layer are coated on the vapor-deposited thin film layer with an uncured coating layer made of an electron beam curable acrylic ink and an acrylic oligomer as a main component. A solar cell back surface protective sheet comprising: an uncured resin layer made of an agent, which is sequentially laminated and then cured by irradiation with an electron beam.

  The invention according to claim 2 of the present invention is the back protective sheet for solar cells according to the invention according to claim 1, wherein the inorganic oxide is aluminum oxide, silicon oxide or a mixture thereof. is there.

  The invention according to claim 3 of the present invention uses the solar cell back surface protective sheet according to claim 1 or 2 so that the weather resistant resin layer of the solar cell back surface protective sheet is the outermost surface. It is a solar cell module characterized by comprising what was unitized.

  The back protective sheet for solar cell of the present invention has a colored layer and a weather-resistant resin layer on the vapor-deposited thin film layer surface of a gas barrier laminated film layer formed by laminating a vapor-deposited thin film layer of an inorganic oxide on one side of a base material layer. In the back protective sheet for solar cells, which is sequentially laminated, the colored layer and the weather-resistant resin layer are coated on the vapor-deposited thin film layer with an uncured coating layer made of an electron beam curable acrylic ink and an acrylic oligomer as a main component. Since the uncured resin layer made of an agent is sequentially laminated and then cured by irradiating an electron beam, the inorganic oxide is aluminum oxide, silicon oxide or a mixture thereof, so that excellent weather resistance, It has moisture resistance and design. Using the solar cell back surface protective sheet, the solar cell module unitized so that the weather resistant resin layer of the solar cell back surface protective sheet is the outermost surface has good weather resistance, can withstand long-term use, and is low Price is also possible, and since it has a colored layer, it can be differentiated from other products.

  The back surface protection sheet for solar cells of this invention and a solar cell module using the same are demonstrated in detail below along embodiment. FIG. 1 is a side sectional view showing an embodiment of a back surface protection sheet for solar cells of the present invention. The back surface protection sheet for solar cells (1) is an inorganic oxide vapor-deposited thin film on one side of a substrate layer (11). In this structure, a colored layer (13) and a weather resistant resin layer (14) are sequentially laminated on the surface of the vapor-deposited thin film layer (12) of the gas barrier laminated film layer (10) formed by laminating the layer (12).

  Further, the gas barrier laminate film (10) may be obtained by further laminating a gas barrier coating layer on the deposited thin film layer (12), and the gas barrier coating layer includes polyvinyl alcohol and one or more metal alkoxides. And the thing containing its hydrolyzate is preferable, and since the thickness after drying will become easy to produce a crack when it exceeds 50 micrometers, it is desirable to set it as 0.01-50 micrometers. In this case, the colored layer (13) is laminated on the gas barrier coating layer.

The base material layer (11) is made of a heat-resistant film, for example, a polyester film such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), a polyamide film, a polycarbonate film, a polyacrylonitrile film, a polyimide. Engineering plastic films such as films are used. In particular, a biaxially stretched film is preferably used among these, and a biaxially stretched nylon film and a biaxially stretched polyester film are preferable, and among them, a biaxially stretched polyester film is more preferable. The thickness of the film is not particularly limited, but generally 6 to 30 μm is more preferable.

  The vapor-deposited thin film layer (12) is made of aluminum oxide, silicon oxide or a mixture thereof, and has excellent gas barrier properties and excellent moisture resistance. The film thickness is preferably in the range of 5 to 300 nm, and the value is appropriately selected. However, if the film thickness is less than 5 nm, a uniform film may not be obtained or the film thickness may not be sufficient, and the function as a gas barrier material may not be sufficiently achieved. In addition, when the film thickness exceeds 300 nm, the thin film cannot maintain flexibility, and there is a possibility that the thin film may be cracked due to external factors such as bending and pulling after the film formation. Preferably, it exists in the range of 10-150 nm.

  As the method for forming the vapor-deposited thin film layer (12), it can be formed by a normal vacuum vapor deposition method, but other thin film formation methods such as sputtering, ion plating, and plasma vapor deposition (CVD). Etc. can also be used. However, considering productivity, the vacuum deposition method is the best at present.

  The colored layer (13) is formed by irradiating an uncured coating layer made of an electron beam curable acrylic ink with an electron beam and curing it. The back surface protection sheet (1) for solar cells of this invention can provide the outstanding designability by forming a colored layer using the electron beam curable acrylic ink of various colors.

  The weather resistant resin layer (14) is formed by irradiating and curing an uncured resin layer composed of a coating agent mainly composed of an acrylic oligomer with an electron beam, and has excellent weather resistance. Yes. The thickness after curing is 10 to 300 μm. The coating agent is composed of a polyester monomer, a polyether acrylate, an acrylic acrylate, a urethane acrylate, an epoxy acrylate, a silicone acrylate, a polyacetal acrylate, a polybutadiene acrylate, a melamine acrylate, or other acrylic oligomer blended with a polymerizable monomer. . The polymerizable monomer is blended for viscosity adjustment. Examples of the polymerizable monomer used include hexyl acrylate, 2-ethylhexyl acrylate, isobornyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, ethoxy-ethyl acrylate, lauryl vinyl ether, 2-ethylhexyl vinyl ether, N-vinylformamide, Examples include decyl acrylate, isooctyl acrylate, vinyl-caprolactam, N-vinyl pyrrolidone, 1,6-hexanediol diacrylate, and neopentyl glycol diacrylate. Among these, isobonyl acrylate is preferable because of excellent weather resistance. .

  The colored layer (13) and the weather resistant resin layer (14) are formed by using an uncured coating layer made of an electron beam curable acrylic ink and an acrylic oligomer as a main component on the deposited thin film layer (12). An uncured resin film layer made of a coating agent is laminated in two layers in the above order by, for example, a die coating method, and irradiated with an electron beam from above to form the two layers simultaneously. Therefore, the adhesive strength between the colored layer (13) and the weather resistant resin layer (14) becomes very strong.

  FIG. 2 is a cross-sectional explanatory view showing an embodiment of a solar cell module unitized using the back surface protection sheet for solar cells of the present invention. The solar cell module (100) includes an upper transparent material (101) and a filler. (102), solar cell element (103), wiring (104), solar cell back surface protection sheet (1), sealing material (105), frame (106), and solar cell back surface protection sheet ( 1) is used such that the weather-resistant resin layer (14) surface is on the outside. Therefore, the solar cell module (100) of the present invention has good weather resistance, can withstand long-term use, and has excellent design.

  The upper transparent material (101) has good light transmittance, excellent weather resistance for a long period (about 20 years), little decrease in light transmittance, dust and the like are less likely to adhere, scratches It is necessary to have various functions such as being hard to stick and having a very low water vapor transmission rate, and glass, acrylic resin, polycarbonate resin, silicone resin, fluorine resin, and the like are used.

  The filler (102) has a high transmittance of sunlight, no change in physical properties such as a decrease in light transmittance due to long-term outdoor standing, etc., high insulation resistance, and no corrosion of other materials. In addition, it must have various functions such as no cracking of the resin due to sudden changes in the outside air condition, interfacial peeling, etc., polyvinyl butyral resin, silicone resin, vinyl chloride resin, polyurethane resin, ethylene / vinyl acetate copolymer Combined resins can be used.

  The sealing material (105) is not particularly limited as long as it can be sealed. For example, butyl rubber or the like is used.

  The frame (106) is generally made of an aluminum frame.

  An example of a method for producing the solar cell module of the present invention will be described below. A solar cell element (103) connected in advance with a wire is sandwiched between two filler sheets made of an ethylene / vinyl acetate copolymer resin having a thickness of 300 μm. After being sandwiched between, the upper transparent material (101) made of a tempered glass plate is placed on one filler sheet, and the solar cell back surface protective sheet (1) is placed on the opposite filler sheet on the weather resistant resin layer (14 ) To the outermost surface, and then preheated at 40 ° C. for 5 minutes, and further hot pressed at 150 ° C. for about 30 minutes from both sides to melt the back surface protection sheet (1) for solar cells. The solar cell module is manufactured by attaching and integrating, sealing the ends with butyl rubber, and fixing with an aluminum frame (106).

  Although the back surface protection sheet for solar cells of this invention is demonstrated according to a specific Example below, this invention is not limited to these Examples.

  As a base material layer (11), a biaxially stretched polyester film having a thickness of 12 μm is used, and a gas barrier property obtained by laminating a vapor deposited thin film layer (12) of aluminum oxide having a thickness of 50 nm on one surface of the biaxially stretched polyester film. A laminated film (10) is prepared, and then a blue pigment is blended with a medium (trade name: CSEB5 medium) of Showa Ink Industry Co., Ltd. on the surface of the vapor-deposited thin film layer (12) of the gas barrier laminated film (10). In addition, an uncured coating layer made of an electron beam curable acrylic ink to which a curing initiator (IRGACURE819) from Ciba Specialty Chemicals was added, an acrylic oligomer (trade name: KRM7818) from Daicel UCB, and isobonyl acrylate and Adds Ciba Specialty Chemicals curing initiator (IRGACURE 184) After the uncured resin layer made of the coating agent was laminated into two layers by the die coating method, the electron beam was irradiated from above to cure the two layers at the same time, and the colored layer (13) and the weather resistant resin layer (14) were respectively formed. It formed and the back surface protection sheet for solar cells of this invention was created.

  In Example 1, the back surface protection sheet for solar cells of this invention was created similarly except having laminated | stacked the vapor deposition thin film layer (12) of silicon oxide instead of aluminum oxide.

  Examples for comparison of the present invention will be described below.

A colored layer composed of a polyurethane-based ink film is laminated on the vapor-deposited thin film layer surface of a gas barrier laminated film obtained by laminating a vapor-deposited thin film layer of 50 nm thick aluminum oxide on one side of a biaxially stretched polyester film having a thickness of 12 μm. A biaxially stretched polyethylene terephthalate film having a thickness of 50 μm was laminated on a 5 g / m ² (dried) polyurethane adhesive on the substrate to prepare a back protective sheet for a solar cell for comparison.

<Evaluation>
The solar cell back surface protective sheet of Examples 1 and 2 and the solar cell back surface protective sheet for comparison of Example 3 were evaluated by the following accelerated exposure test method to compare the weather resistance. The results are shown in Table 1.
(1) Accelerated exposure test method Using an accelerated exposure test apparatus having a sunshine carbon arc lamp in accordance with the accelerated exposure test method defined in JIS A-1415, the prototype solar cell back surface protection sheet was subjected to an exposure test for 2000 hours. The presence or absence of cracks on the surface opposite to the gas barrier laminated film of the back protective sheet for solar cells after the exposure test was confirmed, and the weather resistance was evaluated.

表１に示すように、実施例１〜２の本発明の太陽電池用裏面保護シートは、２０００時間暴露試験後も、ガスバリア性積層フィルムと反対側の表面に亀裂が無く、耐候性は良好であり、一方、実施例３の比較用の太陽電池用裏面保護シートは、同様の暴露試験後、ガスバリア性積層フィルムの反対側の表面に亀裂が生じ、耐候性は悪かった。

As shown in Table 1, the back surface protective sheet for solar cell of the present invention of Examples 1 and 2 has no crack on the surface opposite to the gas barrier laminate film and has good weather resistance even after the 2000 hour exposure test. On the other hand, the comparative solar cell back protective sheet of Example 3 was cracked on the opposite surface of the gas barrier laminate film after the same exposure test, and the weather resistance was poor.

It is a sectional side view which shows one Embodiment of the back surface protection sheet for solar cells of this invention. It is sectional explanatory drawing which shows one Embodiment of the solar cell module unitized using the back surface protection sheet for solar cells of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solar cell back surface protection sheet 10 ... Gas barrier property laminated film 11 ... Base material layer 12 ... Deposition thin film layer 13 ... Colored layer 14 ... Weather-resistant resin layer 100 ... Solar cell module 101 ... Upper transparent material 102 ... Filler 103 ... Solar cell element 104 ... wiring 105 ... sealing material 106 ... frame

Claims (3)

  A back surface protection sheet for solar cells, in which a colored layer and a weather-resistant resin layer are sequentially laminated on the vapor-deposited thin film layer surface of a gas barrier laminated film layer in which at least an inorganic oxide vapor-deposited thin film layer is laminated on one side of a base material layer In this, the colored layer and the weather-resistant resin layer are sequentially laminated on the vapor-deposited thin film layer with an uncured coating layer composed of an electron beam curable acrylic ink and an uncured resin layer composed of a coating agent mainly composed of an acrylic oligomer. A back protective sheet for solar cells, comprising a material cured by irradiation with an electron beam.   The back protective sheet for solar cells according to claim 1, wherein the inorganic oxide is aluminum oxide, silicon oxide or a mixture thereof.   A solar cell comprising the solar cell back surface protective sheet according to claim 1 or 2 and unitized so that the weather resistant resin layer of the solar cell back surface protective sheet is the outermost surface. Battery module.

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