JPH0445256Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improved back protection sheet that serves as a lower substrate of a solar cell module.
More specifically, the objective is to provide a back protection sheet that prevents short-circuiting between the moisture-proof metal foil contained in the protection sheet and the electrode portion of the solar cell element, resulting in poor insulation, and that allows modular composite work to be performed more easily and stably. It is something.

The basic function of a solar cell module is to efficiently guide the sun's radiant energy to the solar cell elements, and to protect the solar cell elements and internal wiring so that they can withstand harsh natural environments over long periods of time. . Conventionally, solar cell modules generally have an upper transparent material 7 that serves as a structural support for the entire module as shown in Fig. 1. For example, the upper transparent material 7 such as a glass plate and a painted steel plate or Al foil are sandwiched together. A solar cell element 5 made of mutually wired single crystal silicon or the like is inserted between a back protection sheet 9 such as a vinyl fluoride sheet to prevent damage to the element 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 6 such as silicone resin, and the whole is enclosed and fixed using a frame 8 made of aluminum, stainless steel, etc. Furthermore, in recent years there has been a strong demand for the early commercialization of solar power generation as an alternative to conventional petroleum-based energy, and the filler 6 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. On the other hand, as the weather-resistant and moisture-proof back protection sheet 9, a white vinyl fluoride sheet made by sandwiching 20 to 30μ Al foil is often used, but the mechanical strength of the vinyl fluoride resin is low; And 140-150
℃, the soldering parts of the element electrodes are softened by the heat during pressing, and pinholes are likely to occur due to the protrusions on the soldered parts of the element electrodes, resulting in short circuits and poor insulation.To prevent this, filler sheets are used more than necessary. Measures are being taken such as increasing the thickness and lowering the press temperature to slow down the speed during modular composite molding. Additionally, as the filler sheet and back protection sheet are currently separate, it is not possible to increase the press pressure due to the use of elements that are easily damaged during composite molding, and there are problems with the solar cell module manufacturing process, such as difficulty in removing air. The reality is that there are problems that cannot be achieved with continuity or automation.

This invention was devised in view of the above circumstances, and as a result of research into a manufacturing process for solar cell modules that can be automated, low-cost, and of stable quality, By using a highly insulating heat-resistant film on the inner surface of the film, and a protective sheet laminated with an adhesive resin that can be easily heat-sealed or the same as the filler ethylene-vinyl acetate copolymer resin sheet on the inner surface, We discovered that there are no problems such as poor insulation, and that the process can be significantly shortened, and the filler sheet can be made thinner, leading to cost reductions.
This idea was completed.

That is, as shown in FIG. 2, the present invention is a back protection sheet for a solar cell module consisting of a moisture-proof metal foil 2 with a thickness of 20μ or more bonded to a weather-resistant resin film 1 and an inner resin layer 10. Back protection for a solar cell module consisting of a laminated layer 10 of a highly insulating heat-resistant film 3 that does not melt or soften at temperatures below 150°C and an ethylene-vinyl acetate adhesive resin layer 4 that melts and softens at temperatures below 150°C, preferably below 120°C. An ethylene-vinyl acetate adhesive resin layer 4 which is a sheet and is further laminated.
is a solar cell module backside protective sheet which itself has a thickness of 0.1 to 1.0 m/m and can also be used as a sheet-like solar cell element protective filler.

Here, as an example of the weather-resistant resin film 1 that constitutes the outer surface of the back protection sheet having a laminated structure,
Perfluoroalkoxy resin, tetrafluoroethylene-hexafluoropropylene copolymer, perfluoroethylene-perfluoropropylene-perfluorovinylether terpolymer, ethylene-tetrafluoroethylene copolymer, chloride-trifluoroethylene In addition to fluororesin films selected from ethylene resin, polyvinylidene fluoride, and polyvinyl fluoride, polycarbonate, polymethyl methacrylate, polyacrylate, or polyethylene terephthalate impregnated with or kneaded with ultraviolet absorbers (e.g., benzophenone, benzotriazole, etc.) There are two kinds of films, or composite films of these films.
Resins other than polyethylene terephthalate may be kneaded or impregnated with ultraviolet absorbers as necessary to improve light resistance.

Moisture-proof metal foil 2 is Al foil or Zn foil due to cost.
Or, it is Sn-plated iron foil, which needs to have a thickness of 20μ or more in order to prevent pinholes and prevent whitening due to moisture absorption of the ethylene-vinyl acetate resin used as the filler.

Next, the highly insulating heat-resistant film 3 is not particularly limited as long as it does not soften or melt at the normal heat press temperature of 150°C or lower, but it has low hygroscopicity and
Due to its good electrical insulation and high mechanical strength,
Biaxially oriented polyethylene terephthalate film is preferred.

The ethylene-vinyl acetate adhesive resin layer 4 constituting the innermost surface of the laminated structure melts and softens at 150°C or lower, preferably 120°C or lower, and contains an ultraviolet absorber as necessary. - Partially saponified products of vinyl acetate copolymers and ethylene-vinyl acetate copolymers, modified resins containing acetoxy groups, hydroxyl groups, or carboxyl groups, and further applying silane-based or titanate-based coupling agents to their surfaces; or In addition, it is a transparent sheet with a thickness of 0.1 to 1.0 m/m that has adhesive properties to the glassy and metallic surfaces of solar cell elements, and is itself a part of the filler. can be configured.

The weather-resistant resin film 1, the moisture-proof metal foil 2, and the highly insulating heat-resistant film 3 can be laminated using an adhesive or an adhesive resin film by a method such as a dry lamination method or a heat press method. Use an adhesive or adhesive resin film that has heat resistance above ℃ and weather resistance. In addition, when laminating the ethylene-vinyl acetate-based adhesive resin layer 4 with the highly insulating heat-resistant film 3, in addition to the dry lamination method using an adhesive, the ethylene-vinyl acetate-based adhesive resin is thermally melted to achieve high insulating properties. Direct extrusion coating method on heat-resistant film 3, etc.
The protective sheet of the present invention can be created using known lamination techniques.

When applying the present invention to a solar cell module,
The solar cell element 5, which has been wire-connected in advance, is placed on a glass plate that is the upper transparent material 7 on which the upper protective filler sheet 6 is spread, and the lower protective filler sheet 6' is covered over it, or the lower protective filler sheet 6' is placed on top of the glass plate. Instead, the back protection sheet of the present invention is placed on top of it with the ethylene-vinyl acetate adhesive resin layer 4 side facing inside, and the whole is pressed at 140°C to 150°C under vacuum to fuse and integrate. Then, the ends are enclosed and fixed with a frame 8 made of aluminum or the like.

As described in detail above, the solar cell module back protection sheet of the present invention has an outstanding advantage over conventional protection sheets, especially in terms of module composite suitability. Since short circuits between the electrode and the metal foil in the protective sheet are almost eliminated, not only is the yield improved, but press pressure, time, temperature, etc. can be selected more freely, improving 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
One of the key points is that it is possible to make it into modules through a multiple pressing process, and the risk of element damage is greatly reduced.

As described above, the present invention provides advantages such as stabilizing the quality of solar cell modules, stabilizing manufacturing, and enabling material savings, and is expected to make a significant contribution to the practical use and widespread use of solar power generation.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the structure of a solar cell module to which the conventional back protection sheet and the present invention are applied, and FIG. 2 is a schematic cross-sectional view showing an example of the back protection sheet for a solar cell module of the present invention. be. DESCRIPTION OF SYMBOLS 1... Weather-resistant resin film, 2... Moisture-proof metal foil, 3... Highly insulating heat-resistant film, 4... Adhesive resin layer, 10... Inner surface resin layer.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. Protection of the back surface of a solar cell module comprising a weather-resistant resin film 1, a moisture-proof metal foil 2 with a thickness of 20μ or more, and an inner resin layer 10, which are laminated in this order from the outside to the inside. The inner resin layer 10 of the sheet includes a highly insulating heat-resistant film 3 that does not melt and soften at temperatures below 150°C, and preferably at temperatures below 150°C, preferably at 120°C.
Consists of a laminated structure of an ethylene-vinyl acetate-based adhesive resin layer 4 that melts and softens as follows: a highly insulating heat-resistant film 3 is placed on the moisture-proof metal foil 2 side, and an ethylene-vinyl acetate-based adhesive resin layer 4 is placed on the inside. A protective sheet for the back side of a solar cell module. 2. The solar cell module according to claim 1, wherein the ethylene-vinyl acetate adhesive resin layer 4 has a thickness of 0.1 to 1.0 mm and also serves as a filler sheet for protecting the lower part of the solar cell module. Back protection sheet.