JPH0433146B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a laminated material used as a back protection sheet for a solar cell module. (Configuration of conventional technology and its problems) The basic functions of a solar cell module are to efficiently guide the sun's radiant energy to the solar cell element, and to protect the solar cell element and internal wiring from harsh natural environments for a long period of time. The purpose is to protect it so that it endures. Conventionally, solar cell modules generally have an upper transparent material 9 that serves as a structural support for the entire module as shown in Fig. 1. For example, the upper transparent material 9 such as a glass plate and a painted steel plate or Al foil are sandwiched together. A solar cell element 7 made of monocrystalline silicon or the like is inserted between the back protection sheets 11 such as vinyl fluoride sheets, and furthermore, to prevent damage to the elements due to sudden changes in outside air conditions and to provide electrical insulation. The space between the upper transparent material and the lower substrate material is filled with a filler 8 such as silicone resin, and the whole is sealed and fixed using a frame 10 made of aluminum, stainless steel, etc. Furthermore, in recent years, there has been a strong demand for the early practical application of solar power generation as an alternative to conventional petroleum-based energy, and the filler 8 used in modules has changed from liquid silicone resin to sheet-like butyral resin, and even more. In response to the switch to low-cost ethylene-vinyl acetate copolymer resin sheets, the modular composite method is rapidly progressing to a form that only requires heat pressing. Here, the back protection sheet 11 protects the components inside the solar cell module (solar cell elements, internal wiring, etc.) from external forces such as mechanical shock and pressure from the outside, and also protects the inside of the module from moisture intrusion from the outside. It is an important material provided as a moisture-proof membrane to prevent parts from deteriorating. Conventionally, a laminated material having a structure as shown in a cross-sectional view in FIG. 2 has been used as a back protection sheet. That is, the structure is such that a moisture-proof metal foil 2 is sandwiched between weather-resistant resin films 1 from both sides. The weather-resistant resin film 1 is a white polyvinyl fluoride resin film that does not deteriorate due to sunlight or rain under outdoor exposure conditions when actually used as a solar cell.
Further, as the moisture-proof metal foil 2, for example, aluminum foil or galvanized iron foil is used. However, when using a back protection sheet with such a structure, the mechanical strength of the white polyfluorinated vinyl film is low, and it softens with the heat of 140 to 150°C applied during hot pressing, so it cannot be heated easily. During pressing, the protrusions of the soldered parts of the solar cell element electrodes penetrate the filler layer, and further penetrate the inner white polyfluorinated vinyl film 1 constituting the back protection sheet, and the metal foil 2 in the back protection sheet.
There was a problem in that contact with the metal foil caused a short circuit between the solar cell element and the metal foil, which adversely affected battery performance. Additionally, since the filler sheet and the back protection sheet are currently separate, the pressing pressure cannot be increased due to the use of elements that are easily damaged during composite molding.
There were restrictions on the press pressure, temperature, and time, making it difficult to continuousize and automate the solar cell module manufacturing process, making the work complicated and causing problems in terms of workability. (Object of the Invention) The present invention solves the above-mentioned problems of the prior art, and provides a heat-resistant resin with a glass-like moisture-proof film mainly composed of silicon oxide deposited on both sides of the film as a moisture-proof layer in place of metal foil. By providing the film, it is possible to avoid electrical short circuits between the protrusions of the soldering part of the solar cell element electrode part and the back protective sheet, and also to prevent the layer of adhesive resin, which has good adhesion to glassy materials, from being By providing it on the innermost surface to play the role of the protective layer of the moisture-proof film and the filler, which was previously separated, the purpose is to significantly shorten the process in manufacturing solar cell modules and reduce costs by making the filler sheet thinner. That is. In addition, as a back protection sheet for a solar cell module that has a heat-resistant resin film deposited with a glass-like moisture-proof film as a moisture-proof layer in place of metal foil, a heat-resistant resin film with a glass-like moisture-proof film deposited on one side is used. As an example, there is Japanese Patent Application No. 59-20510 filed by the present applicant, and in the back protection sheet for solar power module of the present invention, by using a heat-resistant resin film with a glassy moisture-proof film deposited on both sides, The moisture-proof function has been further improved, and even if the glass-like moisture-proof film on the inner surface comes into contact with a protrusion on the soldered part of the solar cell element electrode that penetrates the filler layer, pinholes can occur.
By providing a glassy moisture-proof film on the outer surface as well, it is possible to sufficiently maintain the moisture-proof function. (Summary of the Invention) That is, the present invention is a method of laminating a heat-resistant film having at least an electrically insulating glass-like film deposited on both sides on the inner surface of a heat-resistant and weather-resistant resin film that does not melt and soften at temperatures below 150°C. This invention provides a back protection sheet for a solar cell module consisting of a laminate made of a laminate, and since this back protection sheet does not need to contain a conductive moisture-proofing material in its constituent materials, There is no electrical short circuit between the internal wiring, etc.) and the back protection sheet, and as a result, press pressure, time, temperature, etc. can be selected more freely, making heat press work more efficient, and there is no risk of short circuit. Therefore, the thickness of the filler sheet can be reduced to the necessary minimum, so materials can be saved, and furthermore, the back protection sheet can be easily fused to the filler. Alternatively, because the back protection sheet itself has an integrated layer of adhesive resin that functions as a filler, conventionally a multi-step pressing process was required: back material - filler, then filler - element. It is now possible to modularize objects with just one pressing process. (Description of Specific Examples of the Invention) Specific examples of the present invention will be described below with reference to the drawings. FIG. 3 is a cross-sectional view showing one embodiment of the back protection sheet for solar cell modules of the present invention, which has a heat-resistant and weather-resistant resin film 3 and a glassy moisture-proof film 4, 4' deposited on both sides thereof. It is composed of a resin film 5 and an adhesive resin layer 6. The heat-resistant and weather-resistant resin film 3 is laminated on the outer surface of the glassy moisture-proof coating 4 to prevent pinholes from forming in the glassy moisture-proof coating 4 due to external mechanical pressure, impact, etc. Provided as a protective sheet to provide heat press workability,
It will not melt or deteriorate due to the heat applied during the heat press process during solar cell module manufacturing, and will not deteriorate due to sunlight, rain, etc. even under outdoor exposure conditions when actually used as a solar cell. No resin film is used. In particular, since heat press conditions typically involve applying heat of about 150°C, the resin film must not melt and soften at temperatures below 150°C. For example, perfluoroalkoxy resin, tetrafluoroethylene-hexafluoropropylene copolymer, perfluoroethylene-
In addition to fluororesin films selected from perfluoropropylene-perfluorovinylether terpolymer, ethylene-tetrafluoroethylene copolymer, chloride-trifluoroethylene resin, polyvinylidene fluoride, and polyvinyl fluoride, polycarbonate, There is a type of film selected from polymethyl methacrylate, polyacrylate, or polyethylene terephthalate impregnated or kneaded with an ultraviolet absorber (for example, benzophenone or benzotriazole), or a composite film of these films, and these films are made of titanium oxide or the like. It may be kneaded with pigment, or it may be printed solid or with a pattern on at least one side. The thickness thereof is not particularly limited as long as it can ensure the protective effect of the glassy moisture-proof film, but a film having a thickness of 12 μm or more is usually used. The heat-resistant resin film 5, which has electrically insulating glassy moisture-proof coatings 4, 4' deposited on both sides, prevents moisture from entering the solar cell module from outside and deteriorating components such as the solar cell elements and internal wiring. It is established for the purpose of The glassy moisture-proof coatings 4, 4' are preferably inorganic coatings containing silicon oxide as a main component, taking into consideration vapor deposition suitability, continuous film formation, moisture resistance, and cost. In the case of silicon oxide, the chemical composition is usually SiO ₂ , but in the case of a vapor-deposited film, the composition is close to SiO. The thickness of the vapor deposited film is
At least 200Å or more is required for moisture resistance, but
If the thickness exceeds 1000Å, cracks will easily occur in the film, which will actually impair its moisture resistance.
~700 Å is preferred. Furthermore, the heat-resistant resin film 5 used for vapor deposition must have heat resistance so that it will not melt and lose its supporting function for the vapor-deposited film during the heat press during module manufacturing, but there are no particular restrictions in terms of suitability for vapor deposition. , perfluoroalkoxy resin, 4
Fluorinated ethylene-hexafluorinated propylene copolymer,
A fluororesin film selected from perfluoroethylene-perfluoropropylene-perfluorovinyl ether terpolymer, ethylene-tetrafluoroethylene copolymer, chloride-trifluoroethylene resin, polyvinylidene fluoride, and polyvinyl fluoride. Other examples include films made of polycarbonate, polymethyl methacrylate, polyacrylate, polyethylene terephthalate, polyamide, polyvinyl chloride, cellophane, and the like. The thickness of the heat-resistant resin film is not particularly limited as long as it is thick enough to support the vapor-deposited film, but a film having a thickness of 12 μm or more is usually used. In the present invention, since the glassy moisture-proof film is deposited on both sides of the heat-resistant resin film, the moisture-proof property is improved compared to the case where the glassy moisture-proof film is deposited on only one side, and the glassy moisture-proof film on the inner surface is Even if pinholes occur due to contact with protrusions of the soldered part of the electrode part of the solar cell module element during heat pressing of the module composite, the glass-like moisture-proof film 4' on the outer surface is provided. This maintains sufficient moisture resistance. Furthermore, the glassy moisture-proof coating 4' on the inner surface also has the advantage of having good adhesion to fillers. However, in order to maintain a high degree of moisture resistance,
It is preferable that the surface of the glassy moisture-proof film, which is prone to cracking, be protected until the time of heat pressing, and in this respect, an adhesive resin layer 6 having a function as a filler is further laminated on the inner surface of the glassy moisture-proof film 4. In addition to stabilizing the performance as a protective sheet,
It is possible to simplify the module composite process. The adhesive resin layer 6 is placed on the innermost surface of the protective sheet to serve as a cushion material that protects components such as the solar cell elements and internal wiring inside the solar cell module from external mechanical shock and pressure. It has the same function as the filler which was separate from the back protection sheet, and it itself has adhesive properties to glass and metal on the surface of the solar cell element, and has a temperature lower than 150℃, preferably 120℃. It is made of resin that melts and softens at the following temperatures. Specifically, ethylene-acetic acid such as polyvinyl butyral, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-glycidyl methacrylate terpolymer, ethylene-vinyl acetate partially saponified product-organic acid graft quaternary copolymer, etc. Modified resin of vinyl copolymer,
Alternatively, resins made of carboxyl group-containing polyolefins such as maleic anhydride-grafted polyethylene, polyester-modified resins such as ethylene terephthalate-modified alkylene ether terephthalate block copolymers, etc. are used, and the thickness is the same as that of the back cushion of the solar cell module. In order to effectively exhibit the effect as a material, it is preferable that the thickness is 50μ or more. The heat-resistant/weather-resistant resin film 1 and the heat-resistant resin film 5 having glassy moisture-proof coatings 4 and 4' deposited on both sides are formed by a dry laminating method, a heat press method, etc. using an adhesive or an adhesive resin film. Can be laminated, but use adhesive or adhesive film that is heat resistant to 150°C or higher and weather resistant. In addition, when laminating the adhesive resin layer 6 such as polyvinyl butyral, ethylene-vinyl acetate copolymer, and its modified resin on the glassy moisture-proof coating 4, it is possible to use a heat press method as well as heat-melting the adhesive resin to form a glassy moisture-proof coating. The protective sheet of the present invention can be produced using known lamination techniques, such as direct extrusion coating onto the film 4'. When the protective sheet of the present invention is applied to a solar cell module, the solar cell element 7 that has been wired in advance is placed on a glass plate that is the upper transparent material 9 on which the upper protective filler sheet 8 is spread, and then the lower Either cover with the protective filler sheet 8 or without using it, cover the back protection sheet of the present invention with the adhesive resin layer 6 side facing inside, and heat the whole body to 140°C to 150°C while reducing the pressure in a vacuum. The parts are pressed and fused together, and the ends are enclosed and fixed with a frame 10 made of aluminum or the like. As described in detail above, the back protection sheet for solar cell modules of the present invention has outstanding advantages over conventional protection sheets, especially in terms of module composite suitability. Since short circuits between the element electrodes and the protective sheet are completely eliminated, not only is the yield improved, but the press pressure, time, temperature, etc. can be selected more freely, which improves work efficiency. Since there is no risk of short circuit, it is possible to minimize the thickness of the filler sheet and save on materials. Because a part of the back protection sheet can become the filler or can be easily fused with the filler, conventionally, multi-stage pressing was required under different conditions such as back material - filler, then filler - element. , almost 1
It is possible to make it into a module through the multiple pressing process, and damage to the elements is greatly reduced.Also, in terms of moisture-proofing function, the glass-like moisture-proof coating is double-layered, making it highly durable. It has the advantage of being able to maintain its moisture-proofing function sufficiently even after severe mechanical pressure and shock are applied during the pressing process when combining modules. As described in detail above, the present invention provides advantages such as stabilizing the quality of solar cell modules, stabilizing manufacturing, and making it possible to save materials, and has great value in industrial fields related to solar power generation. It is something. (Description of Examples) Examples of the present invention will be described below. Two types of laminated materials having the following configurations were created as back protection sheets for solar cell modules of the present invention. <Invention 1> Ultraviolet absorber kneaded polyester film (product name: Lumira-Q-37 [manufactured by Toray Industries, Inc.] thickness 25μ)/
Double-sided silicon oxide vapor-deposited polyester film ([manufactured by Oike Kogyo] thickness 12μ) <Invention 2> Polycarbonate film (product name: Panlite [manufactured by Teijin Ltd.] thickness 50μ) / double-sided silicon oxide vapor-deposited polyamide film ([ Made by Oike Kogyo] Thickness
15 μ) / ethylene-vinyl acetate copolymer resin layer (vinyl acetate content: 33% by weight, thickness: 400 μ) As the above two types of laminated materials of the present invention and the laminated materials of the conventional example, white polyfluorinated vinyl film (product Name: Tedlar [manufactured by Dupont] thickness 38μ) /
A solar cell module with a structure similar to that shown in Figure 1 using a laminated material consisting of aluminum foil (thickness 20μ)/white polyfluorinated vinyl film (trade name: Tedlar, thickness 38μ) as the back protection sheet. was manufactured. However, when using the laminated materials of Invention 1 and the conventional example as a back protection sheet, the same sheet as the ethylene-vinyl acetate copolymer resin layer used as the adhesive resin layer in the laminated material of Invention 2 is used. A solar cell module was manufactured using the compound as a filler. In addition, the conditions of heat press are
150°C-5Kg/ ^cm2-10 minutes. Moisture permeability of these three types of back protection sheets for solar cell modules, and soldering parts of solar cell element electrodes when 100 solar cell modules each were manufactured by combining the three types of back protection sheets into modules. The table below shows the results of a comparison of the incidence of battery performance failures due to electrical shorts between the protrusions and the back protection sheet, and the workability of manufacturing operations.

[Table] As described above, by using the back protection sheet for solar cell modules of the present invention, a high degree of moisture-proofing function can be obtained, and the quality of the battery can be stabilized.
This was effective in simplifying module manufacturing work.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing the structure of a solar cell module to which the back protection sheet of the conventional and present invention is applied, FIG. 2 is a schematic sectional view showing the back protection sheet of a conventional solar cell module, and FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows one Example of the back surface protection sheet for solar cell modules of this invention. 1... Weather-resistant resin film, 2... Moisture-proof metal foil, 3... Heat-resistant/weather-resistant resin film, 4,
4'... Electrically insulating glassy moisture-proof film, 5... Heat-resistant resin film, 6... Adhesive resin layer, 7...
Solar cell element, 8... Filler, 9... Upper transparent material, 10... Frame, 11... Back protective sheet.

Claims (1)

[Claims] 1. Heat resistance that does not melt and soften at temperatures below 150°C;
A back protection sheet for a solar cell module, comprising a heat-resistant film having at least an electrically insulating glassy moisture-proof film deposited on both sides on the inner surface of a weather-resistant resin film, and an adhesive resin layer further provided on top of the heat-resistant film. 2. The back protection sheet for a solar cell module according to claim 1, wherein the electrically insulating glassy moisture-proof coating contains silicon oxide as a main component. 3. The back protective sheet for a solar cell module according to claim 1, wherein the adhesive resin layer is a resin layer that has adhesiveness to glass and metal and melts and softens at a temperature of less than 150°C, preferably 120°C or less.