Solar cell module and manufacturing method thereof

Abstract: A solar cell module is provided which is excellent in folding workability and durability. The filler thickness in the suspended part 101, engagement part 103, rising part 104 and engagement part 105 of solar cell module 101 are made thinner than the filler that is placed other parts than these fold molded parts.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a solar cell module and a production process thereof. Related Background Art Solar cell which utilizes solar energy is expected to be a clean and reproducible energy source, from home use to large scale electricity generation. In particular, the use of solar cell module on roofs of buildings is expected as means utilizing limited spaces. Solar cell module built in roof structure holds big promise to reduce the construction cost of building because such solar cell module is built as the part of the construction and does not need frame for setting. The durability against environmental conditions such as temperature, humidity and shock is required when solar cells are used. For this purpose, usual solar cell module used conventionally is made by sealing the solar cell elements in a filler and by covering the surface with a durable plastic film or glass plate. Most preferable structure for integral type solar cell module built in a building roof is that the solar module is made in the following manner: the front side surface is sealed by a durable plastic film protector; a reinforcing plate is used in the back side surface using no frame; and the non-generating area is applied to plasticity processing integrally with the reinforcing plate. Solar module of such structure, which is mechanically reinforced by folding work, not by use of frame, has the following advantages. It has no joint part between main body of the cell elements and the frame, and has no needs of water proof treatment, this means it is advantageous for flushing. It also does not need material and setting work for the frame, and results in the cost reduction of the building. It is also lighter than the framed module, and is easy to handle. Stiffness of the module can be advantageous for jointing and overlapping at the construction step; consequently strong and reliable construction can be made. When a usual metallic material is used for the back reinforcing plate, it can be set on the building roof just like as the usual roofing material. Consequently, the reliability of the module as the roofing material can be increased; thereby, popularization of the module can be assured with the interchange ability of the module with the usual roofing material. The present inventors have developed the solar cell module that includes solar cell element, back reinforcing plate and a durable plastic film for environment protection. The protection of the back reinforcing plate by a durable plastic film is required to prevent the peeling between the cell elements and the back reinforcing plate, and to protect from the leakage of water in raining. There were the following problems in such a solar cell module, which is composed of solar cell elements and back reinforcing metal plate and applied to plastic processing integrally. At first, the module tends to be cracked in the filler at the folding portion, because the module uses the filler to protect the cell elements and the folding work creates large stress in the folding peripheral of the filler material. This crack causes problems not only on the appearance of the module but also the deterioration of elements due to the leakage of water through the cracked channel reaching to the cell elements. There is also the problem that the protection film tends to crack. Usually filler holder is embedded in the filler material of the solar cell module, and the peeling occurs between the filler material and the holder; the holder is torn because of the bending strain and the folding portion is subjected to whitening. This whitening also gives rise of problems not only in the appearance of the module but also deterioration of the elements caused by the flow of water. The filler holding material is embedded to protect the solar cell elements, it also prevents hot filler leakage during the laminating step of the solar cell modules under heat and vacuum, and it also guides the air to out side of the module during the defoaming under heat and vacuum. For these problems, the present inventors proposed, in JP-A 7-131048, a method in which the holder is removed from the folding portion. However, even this means is not satisfactory for producing solar cell modules commercially because of the following problems. Elastic material that can absorb mechanical shock is used for the filler to protect the solar cell element. The filler tends to return to the original flat plate shape after the solar cell module is molded by folding work, since the filler can not be folded because of the elasticity restoration, even after the back reinforcing plate is folded. There is a problem of so-called spring back in which required folding can not be obtained and insufficient dull angle results. There is also a problem in which peripheries of the module tend to deform wavely. These problems occur when a low strength backing plate for reinforcement, for example a thin steel plate, is used. Referring Fig. 19, the peeling problem is explained. This is the problem that the peelings occur in reference numeral 1905 when solar cell module 1901 is folded to the side of back reinforcing plate 1902 and the force of elasticity restoration, which is the force of filler 1903 to return to the original shape before the folding, exceeds the adhesive strength between filler 1903 and back reinforcing plate 1902. This peeling problem may occur in the folding work, and it also may occur after a long period of outdoor even though there was no problem after the folding. In the case where peeling occurs only in a limited part, the space between the filler and the back reinforcing plate forms a channel for water flow and the electricity generation ability of the solar cell elements deteriorates. There is also a problem that the presence of thick filler material induces difficulty in the folding work for various and complicated bending shapes of the solar cell module. The bending work has problems also for workability. When so-called bender, most simple bending machine that makes bending on the material that is put between a blade and a mold, is used, it is necessary to lift up and down the blade on every bending work; it is time consuming and makes the cost reduction difficult. This problem is more severe for the solar cell modules that have many folding parts. When the module has parallel long size along the folding side, it is necessary to use a blade and a mold that are longer than the size, and the necessary large power made the application difficult. There is also a problem when a molder usually called a roll molder is used to fold the solar cell elements for the purpose of avoiding the problem associated with the use of the bender. By referring Figs. 20-22, roll molders are explained. The modules are molded step by step in several stages between the upper and lower molding rollers. Various shapes of the roller are used for the roller molding. Fig. 20 shows a schematic front view of an upper and a lower molding rollers. The module material to be worked 2001 is put between the upper roller 2002 and lower roller 2003, as shown in Fig. 20, and molded. The rollers have the function to transport the module material 2001 in a constant speed in addition to the function to bend. The rollers have also the function to make necessary adjustment. Fig. 21 is a schematic drawing of a group of the upper and lower rollers. The module material is transported from the right side to the left side of the figure, and molded gradually. Complex and good molding is possible when the steps of rollers are larger, since the molding step can be divided in many stages. Fig. 22 explains the molding process in the roller molding. The material is processed gradually in many steps as shown in Fig. 22 and molded to the final shape. The merits of this molding method are that the complex cutting face of mold can be made in one series processing, that it is possible to make folding mold of a long shape of solar cell module, and that it is also possible to mold materials in good surface condition, with good shape and size precision. However, there is a problem in this method in that cutting and concave may be formed in the filler when the solar cell module is processed. There is also another problem that the process may cause scar and cut in the weather resistant-plastic film. These problems are explained by referring to Fig. 23. Fig. 23 is a schematic front view of the upper and lower rollers and solar cell module that is in the course of molding. As shown in the figure, the face of the solar cell module 2301 is pressed at the two points 2307, by upper molding roller 2305, when the solar cell module 2301 is folded to the side of back reinforcing plate 2302. Since the filler is thick and has large elasticity in this part, the problem of depression and tear of the filler occurs. Also, the problems that the scar and tear of the wear resistant plastic film occurred at the point. In addition, it is a problem that a molding size precision is impaired by the absorption of the molding load by the thick filler. These are not only the problem in the appearance of the finished module, but also the problem that may cause cracking and peeling of the filler by the concave and cut in the filler; the scar or damage of the filler may deteriorate the performance of the solar cell module by water flowing in along the peeling and damage of the weather resistant film. It is necessary to increase the roller pressure in order to get enough folding effect of the rollers, because the pressure tends to be absorbed by the filler; the high pressure also deteriorates the performance of solar cell element. As described above, conventional method of molding a solar cell module by folding work is difficult and unreliable; thereby, deterioration of solar cell module has been brought in a long term service. DE-U-93 12 518 discloses a solar cell module which is formed by laminating a glass fiber woven 3, first and second EVA fusible films 5a, 5b with at least one solar cell 4 in between, and an E/TFE laminate film 7 on a back reinforcing plate 2. The fusible films, which represent a filler material, are fused to bury the at least one solar cell. Before or after fusing, the substrate is folded in the non-generating area of the solar cell module so as to form a mounting flange. According to the embodiment shown in Figs. 1 and 1a, the laminate film 7 is adhered to one of the fusible films 5a and 5b in the generating-area of the solar cell module whereas the laminate film 7 is directly adhered to the carrier plate 2 in the non-generating area 6. SUMMARY OF THE INVENTION An object of the present invention is to provide a solar cell module that is excellent in fold molding workability and in durability. The present invention is to solve the problems explained above and to attain the object mentioned above by a solar cell module comprising a weather resistant film (305), solar cell elements (304), a filler (303) for burying the solar cell elements, and a back reinforcing plate (302), with the non-generating area of the solar cell module being folded, wherein the filler (303) is applied to both the generating and non-generating area of the solar cell module and the thickness of the filler (303) is thinner in the non-generating area of the solar cell module so that the generating area of the solar cell module represents a thick part and the non-generating area has a thin part to which said folding is applied. The invention concerns a method of manufacturing a solar cell module as featured in claim 1. It is preferable that the filler thickness of the flat plane area containing thinner filler mentioned above is not less than 5 µm and not more than 1000 µm. It is further preferable that a material for holding the filler is buried in the filler and that the flat plane area containing thinner filler does not have a buried material for holding the filler. It is further preferable that the material for holding the filler is non-woven fabric or woven fabric. It is further preferable that the non-woven fabric or woven fabric is ceramic non-woven fabric or woven fabric, glass non-woven fabric or woven fabric, or polypropylene non-woven fabric or woven fabric. It is further preferable that the weather resistant film is a non-oriented film. It is further preferable that the back reinforcing plate is a metal plate. It is further preferable that the solar cell elements are bendable. It is further preferable that the solar cell elements are amorphous silicon solar cell elements having, on a conductive substrate, a metallic electrode layer, amorphous silicon semiconductor layer, transparent conductive layer, and a grid electrode. It is further preferable that the solar cell elements are amorphous silicon solar cell elements connected in series with plural amorphous silicon solar cells that have, on a conductive substrate, a metallic electrode layer, amorphous silicon semiconductor layer, transparent conductive layer, and a grid electrode. It is further preferable that the folding is applied by using a roll molding machine. The solar cell according to the present invention has durability against external environment such as temperature, humidity, wind and rain since the weather resistant film protects the module. Durability against external environment such as temperature, humidity, wind and rain is also brought by the filler that buries the solar cell elements, which also protects the solar cell from impact. Strength as a structure is maintained by the back reinforcing plate and by the fold molding. Thereby, frame body is now unnecessary, which makes the module light and the cost reduced. Fixed installation is possible by using the fold working part. Since the fold molding is applied at the flat area where the filler is thin, the amount of filler is reduced; thereby, bending strain is decreased and peeling between the back reinforcing plate and the filler is prevented. Also, problem of spring back, in which required angle is not available and only insufficient dull angle is attained, is overcome since the elasticity restoration of filler is decreased. Problem of waving at the edge of a solar cell module when folding is applied near the edge of the solar cell module is also cleared. In addition, problems of cutting and collapsing occurring in weather resistant film and filler when folding is applied by a roll molding machine are also avoided. The pressure applied to solar cell elements is reduced since the pressure to the presser roll of the roll molding machine is mitigated. Furthermore, the amount of filler to be used is decreased, which contributes to cost reduction. The present inventors have studied on the thickness of filler by evaluating the folding part, in which evaluation test samples are prepared and allowed to bent. At first, the filler thickness at the folding part was varied to 1 µm, 5 µm, 10 µm, 100 µm, 500 µm, 1000 µm, 1500 µm, and 2000 µm, for preparing the test samples of the solar cell module. The experiment samples were made as follows. Fillers in sheet form of 1000 µm thickness respectively were laminated on and under the solar cell elements. For the samples of filler thickness of 1 µm, 5 µm, 10 µm and 100 µm, the filler was coated on to the back reinforcing plate. For the samples of filler thickness of 500 µm, 1000 µm, 1500 µm and 2000 µm, the filler in sheet form of 500 µm thickness is laminated in required number of the sheet. In this way, the filler lamination of the fold molding work area was made. These fillers and solar cell elements were inserted between a rectangular back reinforcing plate and a weather resistant film; a vacuum laminator was applied there and the fillers were melted at 150°C. Solar cell modules were thus prepared. EVA (ethylene-vinyl acetate copolymer) was used as the filler. The experiment samples, prepared in this way, were subjected to folding (bending) by a roll molding machine, and the appearance was evaluated. The shape of folding was: the solar cell module was pulled down vertically by 1 cm along the lengthwise direction to the back reinforcing plate side. Table 1 shows the result. Durability of these samples against the change of temperature was evaluated by visual observation of the folded part after 50 times repetition of a test cycle condition consisting of at 40°C for 1 hour and at 85°C for 1 hour. Filler Thickness (µm) Folding by Roller Folding by Bender Initial After Temperature Change Initial After Temperature Change 1 G G G P(2) 5 G G G G 10 G G G G 100 G G G G 500 G G G G 1000 G G G G 1500 P(1) P(1) G P(2) 2000 P(1) P(1) P(2) P(2) Results by folding using a mold and a knife are also shown in Table 1 for the purpose of comparison. The evaluation criterion is as follows. G (good): No appearance change was observed. P (poor) (1): Cut or concave. P (poor) (2): Peeling between the back reinforcing plate and the filler was observed. In the sample of 1 µm filler thickness, the adhesive strength of the filler lowered after the varying temperature cycles and peeling between the back reinforcing plate and the filler was observed. It has been found that enough adhesive strength requires 5 µm or more film thickness. In the samples of 1500 µm or more filler thickness, cutting of the weather resistant film and filler were observed in most portions along with the folding line near but apart from the bent part by the roller molding machine. The folding by the bender also caused the peeling between the back reinforcing plate and the filler since the adhesive strength between the back reinforcing plate and the filler was insufficient compared to the elasticity restoration of the filler and weather resistant film. It has been found that the filler thickness should be not more than 1000 µm for the rolling work on the surface of solar cell module without troubles and for preventing peel of the filler. As found, the problems mentioned before are surely solved by making the filler thickness, in the thinner flat area of the mentioned filler, not less than 5 µm and not more than 1000 µm. In addition, by not burying the material for holding the filler, the solar cell element parts are protected by the filler holding material, flow out of the filler is prevented at an elevated temperature when the solar cell modules are laminated under vacuum and heat, the air remaining in the solar cell module is exhausted to outside, and the problems causing deterioration of the solar cell module is avoided including white turbidity of the folding part brought by peeling between the filler and the filler holding material and their cutting and the water flow therein. By the fact that the material for holding the filler is non-woven fabric or woven fabric, high light transmittance, high porosity and high strength result. By these effects, flow out of the filler is further prevented at an elevated temperature when the solar cell modules are laminated under vacuum and heat, the air remaining in the solar cell module is further exhausted to outside. Decrease of the incident light is also kept to a minimum extent. When the non-woven fabric or woven fabric is ceramic non-woven fabric or woven fabric, glass non-woven fabric or woven fabric, or polypropylene non-woven fabric or woven fabric, high light transmittance, high porosity and high strength are secured. Thereby, enough protection against scratch and impact to the solar cell module results. With the high light transmittance, the incident light decreases by a minimum degree. Deterioration and discoloration for a long period of time are inhibited, and disadvantageous effects are prevented. Since the solar cell modules are not deteriorated when they are laminated under vacuum and heat, flow out of the filler is prevented at an elevated temperature in this process and the effect to exhaust the remaining air in the solar cell module outside is further enhanced. Furthermore, when the weather resistant film is a non-oriented film, elongation of the weather resistant film is large, and the problem of breaking weather resistant film in the step of folding is minimized. The non-oriented film also accommodates the variation of filler from the thick part to the thin part, and cutting or wrinkling does not therefore occur even for a solar cell module in which the thickness varies significantly. Furthermore, when the back reinforcing plate is a metal plate, necessary strength as a structure and excellent workability result. Excellent durability for outdoor use is secured thereby. Since metal plates have been conventionally used as roof materials, the convertibility therebetween is obtained. When the solar cell elements are bendable, the problem of crack in solar cell elements is avoided, and the thickness of solar cell module can be made thin since limited rigidity is required, which contributes to make the weight small and make the cost curtailed. When the solar cell elements are amorphous silicon solar cell elements having, on a conductive substrate, a metallic electrode layer, amorphous silicon semiconductor layer, transparent conductive layer, and a grid electrode, thin solar cell elements can be manufactured inexpensively; less thick solar cell modules contribute reduction of the weight and cost. When the solar cell elements are amorphous silicon solar cell elements connected in series with plural amorphous silicon solar cells that have, on a conductive substrate, a metallic electrode layer, amorphous silicon semiconductor layer, transparent conductive layer, and a grid electrode, manufacturing larger solar cell modules can be possible; thereby, array of solar cells with a broad area can be constituted with a smaller number of solar cell modules. Require parts and workmanship per module are consequently reduced; thereby, the cost is down. When the folding is applied by using a roll molding machine, the fabrication is continuous with high productivity, and the folding is possible in a shorter period and less expensively than the case where a bending machine with a receiver mold and knife is used. Thereby, molding shapes with complicated cross-section is possible, and large and long modules can be manufactured simply. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an outside drawing of a solar cell module of an embodiment and an example of the present invention; Fig. 2 is an upper outside drawing of a solar cell module of an embodiment and an example of the present invention; Fig. 3 is a cross-sectional schematic drawing of a solar cell module of an embodiment and an example of the present invention; Fig. 4 is a cross-sectional schematic drawing of an example of the present invention when installed; Fig. 5 is an outside drawing of a solar cell module of an example of the present invention; Fig. 6 is an upper outside drawing of a solar cell module of an example of the present invention; Fig. 7 is a cross-sectional schematic drawing of a solar cell module of an example of the present invention; Fig. 8 is a cross-sectional schematic drawing of a solar cell module of an example of the present invention; Fig. 9 is an outside drawing of a solar cell module of an example of the present invention; Fig. 10 is an upper outside drawing of a solar cell module of an example of the present invention; Fig. 11 is a cross-sectional schematic drawing of an embodiment of the present invention; Fig. 12 is a cross-sectional drawing of a solar cell element of a solar cell module of an example of the present invention; Fig. 13 is a schematic drawing showing constitution of an a-Si solar cell element of an example of the present invention; Fig. 14 is a cross-sectional drawing of an a-Si solar cell element of an example of the present invention; Fig. 15 is a series connection diagram of an a-Si solar cell element of an example of the present invention; Fig. 16 is a back side wiring diagram of a solar cell module of an example of the present invention; Fig. 17 is a cross-sectional drawing showing an example of a filler in the thin part used in the present invention; Fig. 18 is a schematic cross-sectional drawing of a conventional solar cell module; Fig. 19 is a drawing illustrating problems in the forming of a conventional solar cell module; Fig. 20 is a front view of upper and lower molding rolls; Fig. 21 is a schematic drawing of molding rolls' group; Fig. 22 is a flow chart of molding steps by rolls; Fig. 23 is a front view of upper and lower molding rolls; Fig. 24 is a cross-sectional drawing of a solar cell module in another embodiment of the present invention before the folding step; Fig. 25 is a detailed cross-sectional drawing of the module of Fig. 24; Fig. 26 is a cross-sectional drawing of a solar cell module in another embodiment of the present invention before the folding step; Fig. 27 is a detailed cross-sectional drawing of the module of Fig. 26; Fig. 28 is a cross-sectional drawing of a solar cell module in another embodiment of the present invention before the folding step; Fig. 29 is a detailed cross-sectional drawing of the module of Fig. 28; Fig. 30 is an outside drawing of a solar cell module of the present invention; Fig. 31 is a cross-sectional drawing of a solar cell module in another embodiment of the present invention before the folding step; Fig. 32 is a detailed cross-sectional drawing of the module of Fig. 31; Fig. 33 is an outside drawing of another solar cell module of the present invention; Fig. 34 is a cross-sectional drawing of a solar cell module in another embodiment of the present invention before the folding step; and Fig. 35 is a cross-sectional drawing of a solar cell module in another embodiment of the present invention after the folding step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiments, the solar cell module 301 is constructed, as shown in Fig. 3, so that the filler for the non-generating area of the solar cell module is thinner than the filler for the generating area on the solar cell element 304 of the generating area. Each element for the solar cell module of the present invention is explained hereinafter. <Photovoltaic element> While there is no limitation for the type of the solar cell elements used for the present invention, it is preferable that the solar cell is bendable. It is further preferable that amorphous silicon semiconductor is formed on a stainless steel substrate. Since the thickness of an amorphous silicon semiconductor formed on a stainless steel substrate can be made as thin as about 0.1 mm, the amount of the filler for solar cell elements can be reduced. Since the amorphous silicon semiconductor formed on the stainless steel substrate is bendable and the solar cell is hard to be damaged, it is easy to treat and its workability can be excellent. Since the weight of the solar cell element can be made smaller with stainless steel substrate, the thickness of the back reinforcing plate can be reduced, and the material cost can be reduced as a result. Fig. 12 is a schematic cross-sectional view of one embodiment of a solar cell element used for a solar cell module of the present invention. In Fig. 12, reference numeral 1201 designates a substrate, 1202 designates a back reflecting layer, 1203 designates a semiconductor layer as a photoelectric converting element and 1204 designates a transparent conductive layer. The conductive substrate 1201 can be the back reflecting layer 1202. While the above substrate 1201 is not limited, a conductive substrate is preferable in consideration of its bendability and high impact resistance. Examples of the conductive substrates include stainless steel, aluminum, copper, titanium, carbon sheet, steel; and resin films such as polyimide, polyester, polyethylene naphthalide, and epoxy, having conductive layer; and ceramics. While the semiconductor layer 1204 has no restrictive condition, a semiconductor of a compound is suitable such as an amorphous silicon semiconductor, polycrystalline silicon semiconductor, crystalline silicon semiconductor, and copper indium selenide. For the case of amorphous silicon semiconductor, it is formed using plasma CVD of silane gas and others. Polycrystalline silicon semiconductor is formed by molted silicon sheeting or by heat treatment of amorphous silicon semiconductor. As the semiconductor layer composition, pin junction, pn junction or Schottky type junction is used. The semiconductor layer is constructed such as sandwiched at least between the back electrode layer 1202 and the transparent conductive layer 1204. For the back electrode layer 1202, a metallic layer, metallic oxide or a complex layer of a metallic layer and a metallic oxide layer may be used. For the material of the metallic layer, Ti, Al, Ag or Ni may be used. For the metallic oxides layer, ZnO, TiO 2 or SnO 2 may be adopted. For forming the above metallic layer and metallic oxide layer, resistance heating evaporation, electron beam evaporation, spattering method, spray method or CVD method may be used. Furthermore, as for the collector electrode material on the grid for collecting the current effectively generated by the photoelectromotive force on the transparent conductive layer, Ti, Cr, Mo, W, Al, Ag, Ni, Cu, Sn or conductive paste such as silver paste may be used, but the material is not limited to these. For forming the grid electrode, the following methods may be used: spattering with masked pattern, resistance heating, CVD and other vapor deposition, etching and patterning method after entire evaporating of metallic layer, method of direct forming of the grid electrode pattern by optical CVD, method of forming by plating after forming negative mask pattern of the grid electrode, and method of forming by printing conductive paste. As for the conductive paste, fine powder of Au, Ag, Cu, Ni, or carbon which are distributed with a binder polymer, are generally used. Examples of the above binder polymer include resins of polyester, epoxy, acryl, alkyd, polyvinyl acetate, rubber, urethane, and phenol. For the material of bus bar to further collect and transport the current collected by the grid electrode, copper or nickel which are tinned or solder coated are used. Bus bar is connected to the grid electrode by using conductive adhesive or solder. When the back reinforcing plate other than metallic plates is used, a solar cell module which has excellent folding workability, as excellent as by the other embodiments, can be formed, by directly forming amorphous silicon semiconductor on the back reinforcing plate made of insulated material, forming non-generating area in the folding position using laser scribe, and forming the area to contain thinner filler on the folding position. <Back reinforcing metal plate> It is preferable that the back reinforcing plate has the stiffness by fold molding as a structure. Preferably the back reinforcing plate has bendability, excellent workability, strong adhesive ability with the filler layer, and high weather resistance and corrosion resistance. Its gradation of color is preferred to be selectable because it may affect to the outside view according to the installing condition. It is preferable that the back reinforcing plate is metallic. More specifically, examples of the metal plate include copper plate, aluminum alloy plate, titanium plate, stainless steel plate, zinc-galvanized steel plate, zinc-aluminum-galvanized steel plate and other specially galvanized steel plate, and laminated and coated steel plates. It is preferable that the metallic plate is colored by a paint of polyester resin family or epoxy resin family. <Weather resistant film> It is preferable that the weather resistant film has high weather resistance. Preferably it has volatility to prevent contamination. Preferably its elongation is high because of the need of responding to the variation from thicker filler area to thinner filler area, and because of the necessity of following the folding of the back reinforcing plate without tearing. Examples of the weather resistant film includes fluororesin films. Copolymer film of non-extended type ethylene-tetrafluroethylene is more preferable. For the purpose of securing the adhesiveness with the filler layer, a process for making the adhesion easy, such as corona discharge process or making ozone, is preferable. A non-extended type film is preferable. As for the weather resistant film of the solar cell module used for the present invention, its elongation is preferably high for not bringing cracks on the folding position of the film when folded. The crack on the weather resistant film is not desirable, and it may also cause the film peeling. <Filler for burying photovoltaic element> The filler for burying photovoltaic element is preferred to have excellent workability because fold molding is applied to the solar cell module. It is preferable that incident side is transparent to the light that is used for photoelectronic transfer. The adhesiveness and stickability are preferred to be high with the back reinforcing plate, the photovoltaic element and the weather resistant film. The filler is preferred to be a thermoplastic resin for the purpose of filling concave and convex of the photovoltaic element. Copolymer of ethylene-vinyl acetate (EVA), copolymer resin of ethylene acrylate (EEA), polyvinyl butyral (PVB), silicon resin and acrylic resin are preferable examples of the filler. A cross-linking agent and thermal oxidation inhibitor may be added to the filler for improving the heat resistance. The filler that is placed on the back side of the photovoltaic element needs not to be transparent. Different types of fillers may be used depending on their locations such as incident side of the photovoltaic element or its backside, or depending on their locations of presence or absence of the photovoltaic element. A filler holding material, in a form of sheet, of woven fabric or non-woven fabric such as glass and polypropylene may be buried into the filler. <Filler holding material> Filler holding material used in the present invention is for the purpose of preventing the filler from flowing out when the filler temperature is elevated, and protecting the solar cell elements. The filler holding material also functions as exhausting remaining air in the solar cell module to outside when the solar cell module is defoamed under vacuum and heat. Preferable filler holding materials used for the present invention are of high transparency, porosity and stiffness. More specifically, preferable filler holding materials are woven fabric or non-woven fabric of glass, ceramic or polypropylene. <Surface shape of the module> Before the fold molding process, the back reinforcing plate and the weather resistant film are face to face in parallel approximately. In the space between the back reinforcing plate and the weather resistant film, it is necessary that the filler should be thicker and the distance should be long to protect the solar cell element in the area where the solar cell elements exist, and that the filler should be thinner and the distance should be short to get higher workability and reliability after molded at the folding area where the folding work is done. For this purpose, the weather resistant film of the solar cell module surface must be covered continuously from where the filler is thicker to where the filler is thinner. For this purpose, the weather resistant film with high elongation should be used. Thus, the angle of the transition area where the thickness of the filler changes is arbitrary. For this reason, the weather resistant film should have large elongation. Both of the sharp continuity or smooth continuity may be allowed in the solar cell module. The thinner filler part can be exist not only at the edge but also at any part. For example, for the case of approximately rectangular of solar cell module, the thickness of the filler in the facing lengthwise may be reduced not only in the edge but also in all the edges. Other than the edge part, in the center part where the solar cell element does not exist, the filler may have reduced thickness. For performing the roll molding without trouble, it is preferable that the thinner part of the filler has some width along the folding direction in the neighborhood of the folding part where the roller pushes. It is preferable that the thickness of the filler of the flat area where the filler is thinner is not less than 5 µm and not more than 1000 µm. <Preparation method of the module> To fabricate the area where the filler is thinner in the solar cell module, it is necessary to reduce the amount of the filler to be laminated when the composition materials are laminated. To get the required shape, it is necessary to push the mold for restricting the flowing out of filler. If the angle of the transition area where the filler thickness is to change smoothly, the desired shape is obtained by flowing out the filler from its thicker part to its thinner part, without any jig in the assembly. The surface and the corner of the board-like pressing jig are to be treated to have smooth surface for not scratching the weather resistant film. The amount of the filler to be laminated and the thickness of the pushing jig are to be determined not to be wrinkled by slacking of the weather resistant film. An example for forming the thinner filler part, mentioned above, of the solar cell module is explained by referring to Fig. 17. When laminating the constituent materials, the amount of filler to be laminated in the thinner filler part is made smaller than the generating area, for the purpose of increasing the flatness and uniformity of the filler. The sheet type jig 1702, which pushes the thinner part for forming a sharp step in the angle of transposition part from the filler thicker part to its thinner part, is placed from the incident side of the weather resistant film; therein, the filler is melted using a vacuum laminator. The sharp step is formed in this way. Moreover, the thickness of the thinner filler part can be made more thinner by making the pressing jig 1702 more thicker and decreasing the filler volume accordingly. Furthermore, by making the pressing jig 1701 more thinner and increasing the filler volume accordingly, the thickness of the thinner filler part can be made not so thinner. In this way, the thickness of the thinner filler part is adjustable. <Plasticity processing> While there is no limitation for the fold molding method of the solar cell module, it is preferable that the folding is done using a roll forming machine. In this case, preferably, a soft roller such as of urethane resin, avoiding a metal roller, is used for not scratching the weather resistant film. The roller angle R should be large as much as possible. The roller transport speed should be slower for minimizing damage and dimensional error. The surface of solar cell module is generally weather resistant film such as of urethane resin, which is susceptible to surface damage. Hence, the mold of the "folding machine" or "bender" is preferably of a material that would not damage the surface of solar cell module. For example, the weather resistant film surface of a solar cell module is placed on a soft mold of urethane resin and the blade is applied to the back reinforcing plate; in this way, folding is made without damage. [Examples] Now, the present invention is described in details by way of examples, however, the present invention is not limited thereby. Example 1 Fig. 1 is an outside drawing of a solar cell module according to this example. Fig. 2 is an upper outside drawing of the solar cell module of this example before the folding work. Fig. 3 is a cross-sectional drawing along 3-3 of Fig. 2. This example relates to a case, in which a solar cell module that had amorphous silicon solar cell elements, prepared and connected serially on a stainless steel substrate, and had a zinc-galvanized steel on the back face sheet was subjected to folding work; thereafter many such solar cell modules were installed. First, an amorphous silicon solar cell element (Fig. 12) was prepared as follows. By sputtering, 5000 Å thick film of Al (1202) containing 1% Si was formed on a cleaned long stainless steel substrate 1201 of 0.1 mm thickness in a roll form. Next, n/i/p type amorphous silicon semiconductor layers 1203 were sequentially formed by plasma CVD method as follows: an n-type semiconductor layer of 300 Å thickness was formed using PH 3 , SiH 4 and H 2 gases; an i-type semiconductor layer of 400 Å thickness using SiH 4 and H 2 gases; and a p-type semiconductor layer of 100 Å thickness was formed using B 2 H 6 , SiH 4 and H 2 gases. Then, ITO (1204) of 800 Å thickness was formed by resistance heating vapor deposition method to form an amorphous silicon solar cell element 1200. Second, the long solar cell element mentioned above was cut by a press machine to make a plurality of solar cell elements, each being of the size of 30 cm × 15 cm as shown in Fig. 3. In the cut surface of the solar cell elements, cut by the press machine, the solar cell elements were crushed by the press machine; thereby, the ITO electrode and stainless steel substrate were in a condition of short-circuit. For the purpose of repairing this short-circuit, the peripheral areas of ITO electrode of each solar cell element were removed (1301). Removal of the peripheral areas of ITO electrode was done by screen-printing etching agent (FeCl 3 solution) on the peripheral areas of ITO located slightly inside the cut surface of each solar cell element to dissolve ITO and followed by cleaning the areas with water; the etching agent (FeCl 3 solution) had selectivity to dissolve ITO but not to dissolve the amorphous silicon semiconductor. Thus, the separate part of ITO electrode 1301 was formed. Third, collecting grid electrodes 1302 were formed on the ITO by screen-printing a silver paste containing polyester resin as the binder (made by DuPont Company, [5007]). A tin-galvanized copper wire 1303, which is the collecting electrode of the grid electrodes was placed crossing perpendicularly with the grid electrodes. An adhesive silver ink 1304, which was "C220" made by Emarson & Cuming, Inc., was dripped on the cross points of the wire and grid electrodes and dried at 150°C for 30 minutes to connect the tin-galvanized copper wire with grid electrodes. At that occasion, a polyimide tape was pasted to the lower side of the tin-galvanized copper wire 1303 to assure no contact between the end surfaces of stainless steel substrate and the tin-galvanized copper wire. Fourth, the ITO layer/α-Si layer at the part of non-generation area of the amorphous silicon solar cell element were removed by a grinder so that stainless steel substrate be exposed and welded to copper foils 1305 by a spot welder. Fifth, as shown in Fig. 15, the tin-galvanized copper wire 1504 of solar cell element 1501 and the copper foil 1505 of solar cell element 1502 were serially connected by soldering. Likewise, the tin-galvanized copper wire of the solar cell element and the copper foils of adjacent solar cell elements were serially connected by soldering so that 13 solar cell elements be serially connected. Wiring for positive and negative terminal connections was made on the backside of stainless steel substrate. Fig. 16 shows the backside wiring diagram of the solar cell elements connected serially. Insulating polyester tape 1603 was first pasted on the middle part of the 13th solar cell element 1601. Copper foil 1602 was then pasted on it. The positive side wiring was then done by soldering copper foil 1602 with the tin-galvanized copper wire. After copper foil 1606 was connected to the 1st solar cell element 1604 as shown in Fig. 16, the negative side wiring was done by soldering copper foil 1605 that was spot-welded with the 1st solar cell element 1604. Sixth, solar cell module 301 containing solar cell elements 304 that was sealed with the resin and held between zinc-galvanized steel sheet 302 and non-oriented fluororesin film 305, as shown in Fig. 3, was prepared in the following procedures: galvanized sheet iron 302 of 0.3 mm thickness/EVA 303/solar cell elements 304 consisting of 13 serially connected ones explained above/EVA 303/non-oriented copolymer film of ethylene tetraethylene and fluororesin "AFLEX" (Asahi Glass Company) of 50 µm thickness/a jig pushing EVA so that EVA forms a uniform and thin film at the thinner filler portion, were sequentially laminated in this order. Solar cell module 301 was then produced by using a vacuum laminator to melt EVA at 150°C. At that time the amount of EVA laminated at the thinner filler portion was relatively smaller than at the thicker filler portion. The pushing plate jig used was a steel sheet of 1.5 mm thickness. The amount of filler at the thinner filler portion was 1/4 of that at the generating area. Thereby, the solar cell module produced had the filler of 2 mm thickness at the generating area and had the filler of 0.5 mm thickness at the thinner filler portion. The surface, to be adhered, of non-oriented fluororesin film 305 was plasma-treated preliminarily for better adhesion with EVA 303. Solar cell elements 304 serially connected in this procedure were of a size smaller than the backside galvanized steel sheet and the non-oriented fluororesin film 305 so that the end portions of solar cell module 301 be folded at a later process. Seventh, above-mentioned solar cell module 301 was subjected to folding work into the shape as shown in Fig. 1 by a roller former. The suspended engagement portion was made by folding one of the ends perpendicularly as shown by reference numeral 102 and then by folding it at an acute angle into the inside direction twice as shown by reference numeral 103. The rising engagement portion was made by folding the other end portion upwardly at 90 degrees to the direction of the solar cell side as shown by reference numeral 104. It was again folded at an acute angle as shown by reference numeral 105. Finally it was once more folded at an acute angle as shown by reference numeral 105. Fig. 4 shows the engagement (seam) gripping between the rising engagement portion 105 and the suspending engagement portion 103 of the solar cell module. Fig. 4 shows a schematic cross-sectional drawing when a plurality of the solar cell modules of this example were installed on sheathing roof boards. Solar cell module 401 has both rising end 404 and suspending end 402, each end respectively having an engagement portion, 405 and 403. The engagement portions of the two vertically adjacent modules are gripped with each other (seamed). The solar cell module was installed on a supporter 406 by fixing the upward end with a fixing member 407. Joints were used to connect a solar cell module with another adjacent solar cell module located in the direction where no ends folding were available. Filler at the engagement portion of this example was so thin or the portion was so close to roofing materials commonly used that its folding and installing were done with the same degree of ease as handling of roofing materials. This example could produce a lighter solar cell module since no frame was used. As a result, handling at the time of installation, for example, was also easier. The material was less expensive. In addition, no whitening at the bending portion nor cracking in the filler was found. Thus, a solar cell module with good appearance was obtained. No peeling of the filler and weather-resistant film was observed. Thus, reliability of the folding portion was improved. Another advantage was smaller possibility of flame going upward through the engagement portion from the inside or room to the outside or roof in case of fire due to the thin filler layer of the engagement portion. Example 2 Fig. 5 shows outside of a solar cell module in this example; Fig. 6 shows upper outside of the solar cell module before being cut and folded, in this example; Fig. 7 shows a cross-section along 7-7 of Fig. 6, and Fig. 8 shows a cross-section along 8-8 of Fig. 6. This example is a case of cutting and bending solar cell module which consists of amorphous silicon solar cell elements prepared and serially connected on a stainless steel substrate with a galvanized sheet iron on its backside. In this Example 2, the solar cell elements prepared in the same way as in Example 1 was used. Solar cell module 701 containing solar cell elements 704 that is sealed with a resin and held between zinc-galvanized steel sheet 702 and non-oriented fluororesin film 704 as shown in Fig. 7 and was prepared in the following procedures: zinc galvanized steel sheet 702 of 0.3 mm thickness/EVA 703/solar cell elements 704 consisting of 13 serially connected ones/EVA 703/non-oriented copolymer film 705 of ethylene tetraethylene and fluororesin "AFLEX" (Asahi Glass Company) of 50 µm thickness/a jig pushing EVA so that the EVA form a uniform and thin film at the thinner filler portion, were sequentially laminated. Solar cell module 701 was then prepared by using a vacuum laminator to melt the EVA at 150°C. As shown in Figs. 6, 7 and 8, thinner film portion exists in all the four ends in this example resulting in good folding workability at all the four ends. Here, the amount of EVA laminated at the thinner film portion was relatively smaller than at the thicker film portion. Pushing plate jig used was 1.5 mm thick steel sheet. The amount of filler at the thinner filler portion was 1/4 of that at the generating area. Thereby, the solar cell module produced had the filler of 2 mm thickness at the generating area and the filler at the thinner filler portion of 0.5 mm thickness. Then, a corner shear cut all the four corners (as shown in dotted lines in Fig. 6), and a bender folded each of all the four sides at 90 degrees twice to the direction of the backside to make it a box shape. Installation on a supporter was done by screwing through fixing holes 602 from the backside. In this example, a lighter solar cell module was produced since no frame was used. As a result, the handling for installation was also easier. The material cost, too, was inexpensive. In addition, no whitening at the folding part nor cracking in the filler was found. Thus, a solar cell module with good appearance was obtained. No peeling of the filler and weather-resistant film was observed. In this way, reliability of the folded part was improved. Example 3 Fig. 9 is an outside drawing of a solar cell module in this example; Fig. 10 shows the upper outside of the solar cell module before folded in this example; and Fig. 11 shows a cross-section along 11-11 of Fig. 10. This example relates to a case in which many amorphous silicon solar cell elements, prepared and connected serially on a stainless steel substrate, were installed on a solar cell module that had been folded and had a zinc-galvanized steel sheet on the reverse surface. In this Example 2, solar cell elements prepared in the same way as in Example 1 were used. Solar cell module 1101 containing solar cell elements 1104 that was sealed with a resin and held between zinc-galvanized steel sheet 1102 and non-oriented fluororesin film 1105 as shown in Figs. 10 and 11, was prepared in the following procedures: 0.3 mm thick zinc-galvanized steel sheet 1102/EVA 1103/solar cell elements 1104 consisting of 13 serially connected ones/EVA 1103/non-oriented copolymer film 1105 of ethylene tetraethylene and fluororesin "AFLEX" (Asahi Glass Company) of 50 µm thickness/a jig pushing EVA so that EVA form a uniform and thin film at the thinner filler portion, were sequentially laminated. Solar cell module 1101 was then prepared by using a vacuum laminator to melt the EVA at 150°C. Therein, the amount of EVA laminated at the thinner film portion was relatively less than at the thicker film portion. Pushing plate jig used was a steel sheet of 1.5 mm thickness. The amount of filler at the thinner filler portion was 1/4 of that at the generating area. Thereby, the solar cell module produced had the filler of 2 mm thickness at the generating area and the filler of 0.5 mm thickness at the thinner filler portion. Then, above-mentioned solar cell module 1101 was folded by a roller former into the shape as shown in Fig. 9. That is, its central portion was first folded. One of the end portions was then folded to the direction of the backside at an acute angle, twice, to form engagement portion 903. The other opposite end portion was folded at 90 degrees to the direction of the solar cell side as shown by reference numeral 904 and was again bent at an acute angle to the direction of the weather resistant film side. Finally it was once more folded at an acute angle to form rising engagement portion 905. Installation was made in the same manner as in Example 1. In this Example 2, a solar cell module having good folding workability not only at the ends but at the central portion was produced. The module folded at the central portion was able to maximize effective use of the limited area of the solar cell. No whitening at the folding portion nor cracking in the filler was found. Thus, a solar cell module with good appearance was obtained. No peeling of the filler and weather-resistant film was observed. In this way, reliability of the folding portion was improved. Example 4 The solar cell module according to this example is characterized in that gradual taper-shaped change in the thickness of filler from the thicker filler part for protecting the solar cell element to the thinner filler part of the fabrication zone. Fig. 24 shows a schematic sectional view of the solar cell module before folded in this example. Preparation of this solar cell module is explained by referring to Fig. 25. The following materials, prepared, were laminated on a steel sheet having heat source in the following order similarly to Example 1: back reinforcement silicone rubber sheet 2502, filler 2504 in a sheet form, serially connected photovoltaic elements 2501, sheet filler 2504, and weather resistant film 2503. Therein, the thinner sheet filler was laminated in the neighborhood of ends, the fabrication zone. A heat resistant silicone rubber sheet was then placed over the above lamination materials to reduce the pressure between the silicone rubber sheet 2502 and steel sheet 2506 having the heat source to 10 torr by using a vacuum pump. Thereafter, the assembly was heated up to 150°C and kept at 150°C for 30 minutes, and allowed to cool down to room temperature while maintaining the vacuum. Allowing some amount of the filler to flow from the thicker filler area to the thinner filler area, a solar cell module having a gentle sloping surface was obtained. The thickness of the filler was 2 mm at the thicker filler area and 0.5 mm at the thinner filler area. Folding and installing were made in the same way as Example 1. The solar cell module of this example was light with better processability, higher reliability and lower production cost. In addition, compared with Example 1, it also resulted in better appearance nearly same as conventional roof since the gentle sloping surface at the area was made from the thicker filler area to thinner filler area. Example 5 The solar cell module according to this example is characterized in that different kinds of fillers are used in the protection zone for the solar cell elements and in the fabrication zone. Fig. 26 shows the sectional constitution of the solar cell module before folded in this example. Preparation of this solar cell module is explained by referring to Fig. 27. The following lamination materials, prepared similarly to Example 1, were laminated on a steel sheet having heat source in the following order: mold 2708 that limits flow of the filler when heated and determines the module surface shape; weather resistant film 2703; sheet filler 2704 that is placed only in the thicker filler area; serially connected solar cell elements 2701; filler 2704 for the thicker filler area. However, only filler 2708 was laminated in the area of fabrication with thinner filler. In the fabrication area, EEA resin was used as the filler that was different from the filler for the filling and protecting the place around solar cell elements. Thereafter, back reinforcing plate 2702 was placed. Then, a heat resistant silicone rubber sheet was overlapped. Thereafter, the space between the silicone rubber sheet and the steel sheet 2706 having the heat source was subjected to a vacuum of 10 torr by use of a vacuum pump. The assembly was then heated up to 150°C and kept at 150°C for 30 minutes, and allowed to cool to room temperature while the vacuum was maintained. Thereby, a solar cell module in which different kinds of the fillers were used respectively in the module protection area and in the fabrication area was obtained. The thickness of fillers was 2 mm at the thicker filler area and 0.5 mm at the thinner filler area. The folding and installing were made in the same way as Example 1. This example is an example of a solar cell module in which wider selection of the fillers is possible. It is not necessary to select a highly transparent filler for the fabrication zone. It is possible to select a material which can be processed easily compared with the filler for the protection of the solar cell elements. A material of favorable color may be selected. Example 6 The solar cell module according to this example is characterized in that the surface is flat by use of a steel plate that is subjected to a plasticity processing for the back reinforcing plate. Fig. 28 shows a sectional drawing of the solar cell module before folded in this example. Preparation of this solar cell module is explained by referring to Fig. 29. Except the back reinforcing plate, the materials prepared for the lamination in the same way as Example 1 were used. On a steel sheet that was provided with a heat source, weather resistant film 2903, filler 2904, solar cell elements 2901 serially connected, filler 2904, and back reinforcement metal plate 2902 that was folded as shown in the figure were laminated in this order. Then, a sheet of heat resistant silicone rubber was overlapped. Thereafter, the space between the silicone rubber sheet and the steel sheet 2706 having the heat source was subjected to a vacuum of 10 torr by use of a vacuum pump. The assembly was then heated up to 150°C and kept at 150°C for 30 minutes, and allowed to cool to room temperature while the vacuum was maintained. Thereby, a solar cell module was obtained. The thickness of the filler was 2 mm at the thicker filler area and 0.5 mm at the thinner filler area. The folding and installing were made in the same way as Example 1. According to the solar cell module of this example, a solar cell was obtained having a light module that is excellent in processability and reliability and producible inexpensively. In addition, this solar cell had a flat surface giving more natural appearance which did not bring the feeling of the existence of a solar cell. Example 7 The solar cell module according to this example is characterized in that the solar cell module was folded to the incident side. Fig. 30 is an outside view of the solar cell module of this example. In this example, the solar cell module prepared in the same way as in Example 2 was used and installed by folding toward the incident (light receiving) side. The installation was made in a way called batten (ribbed) seam roofing. The solar cell module according to this example made it possible to solve problems such as spring back and waves in the periphery caused when the thicker filler area was folded to the incident side. Example 8 The solar cell module according to this example is characterized in that the thinner filler fabrication area is limited to the folded part and associated minimum area. Fig. 31 shows a cross-section of the solar cell module before folded in this example. Preparation of this solar cell module is explained by referring Fig. 32. On a steel sheet that was provided with a heat source, jig 3207 for formation of the thinner filler layer was placed. Thereafter, the materials for lamination that were prepared in the same way as Example 1 were laminated in the order of weather resistant film 3203, filler 3204, photovolatic elements 3201 serially connected, filler 3204, and back reinforcement metal plate 3202. Then, a sheet of heat resistant silicone rubber was overlapped. Thereafter, the space between the silicone rubber sheet and the steel sheet 3206 having the heat source was subjected to a vacuum of 10 torr by use of a vacuum pump. The assembly was then heated up to 150°C and kept at 150°C for 30 minutes, and allowed to cool to room temperature while the vacuum was maintained. Unlike Example 1, the amount of the filler in a sheet form was made same both in the fabrication area and generating area. The thinner filler part was formed by the flow of the filler from the fabrication area by atmospheric pressure on the back reinforcing metal plate. The thickness of the filler was 2.2 mm at the thicker filler area and 0.8 mm at the thinner filler area. The folding and installing were made in the same way as Example 7. The solar cell module according to this example made it possible to improve the workability of a solar cell module without sacrificing the processability of the solar cell module. Example 9 The solar cell module according to this example is characterized in that two methods for the folding were used, one being a roller former and the other being a mold and a blade. In this example, the solar cell module of Example 2 was used. Fig. 33 shows an outside of the solar cell module of this example. In this example, the four corners of the solar cell module were cut. Both ends of the two longer sides were folded by using a roller former to make the engagement portions for a supporter as shown by reference numeral 3302. Both ends of the two shorter sides were then folded by using a bender machine as shown by reference numeral 3303. According to the solar cell module of this example, the workability was improved by using a roller former for bending the two longer sides. Example 10 The solar cell module according to this example is characterized in-that the back reinforcing plate was exposed at the place closest to the ends. Fig. 34 shows a schematic cross-sectional constitution of the solar cell module of this example before folded in this example. Fig. 35 is a schematic cross-sectional drawing of the folded portion and its neighborhood when the solar cell module of this example is installed. The preparation method of the solar cell is explained at first. On a steel sheet that was provided with a heat source, a mold that limits the flow of the filler when heated and determines the module surface shape and a jig that forms the thinner part of the filler were placed. Thereafter, the materials for lamination that were prepared in the same way as Example 1 were laminated in the order of the weather resistant film, filler, photovoltaic elements serially connected, filler, and back reinforcement metal plate. In these procedures, the weather resistant film and the filler were made smaller so that they do not cover the whole area of the back reinforcing plate. Then, a sheet of heat resistant silicone rubber was overlapped. Thereafter, the space between the silicone rubber sheet and the steel sheet having the heat source was subjected to a vacuum of 10 torr by use of a vacuum pump. The assembly was then heated up to 150°C and kept at 150°C for 30 minutes, and allowed to cool to room temperature while the vacuum was maintained. Thereby, a solar cell module having the back reinforcing plate that was exposed at the place closest to the ends was obtained as shown by reference numeral 3410. The thickness of the filler was 2 mm at the thicker filler area and 0.5 mm at the thinner filler area. The folding and installing were made in the same way as Example 1. As seen in Fig. 35, the place where the adhesion between the back reinforcing plate and the filler starts, was located inside the engagement portion which was not exposed to rain and wind. The solar cell module according to this example shows an example of the surface shape. It is required to have no end nor seam of the weather resistant film at the place exposed to rain and wind. However, it is not necessarily required for the weather resistant film and filler to cover the whole area of the back reinforcing plate. This is because the weather resistant film should not necessarily protect the end portions of the back reinforcing plate which are supposed to be located, after installed, in the place not exposed to rain and wind and also because it is less likely that problems such as, for examples, peeling off the filler and weather resistant film at the area and flowing in of water occur. According to the solar cell module of this example, the amount of both filler and weather resistant film can be reduced; thereby, the production cost can be reduced. Furthermore, better folding workability is attained at the area where no filler is used. [EFFECT] According to the solar cell module of the present invention, durability against external environment such as temperature, humidity, wind and rain since the weather resistant film has been obtained. Durability against external environment such as temperature, humidity, wind and rain has been also brought by the filler that buries the solar cell elements, which also protects the solar cell from impact. Strength as a structure has been maintained by the back reinforcing plate and by the fold molding. Thereby, frame body has become unnecessary, which has made the module light and the cost reduced. Fixed installation is now possible by using the fold working part. By reducing the amount of filler, bending strain has been decreased and peeling between the back reinforcing plate and the filler has been prevented. Also, problem of spring back, in which required angle is not available and only insufficient dull angle is attained, has been overcome since the elasticity restoration of filler is decreased. Problem of waving at the edge of a solar cell module when folding is applied near the edge of the solar cell module has been also cleared. In addition, problems of cutting and collapsing occurring in weather resistant film and filler when folding is applied by a roll molding machine have been also avoided. The pressure applied to solar cell elements is now reduced since the pressure to the presser roll of the roll molding machine is mitigated. Furthermore, the amount of filler to be used has been decreased, contributing to cost reduction. By making the filler thickness, in the thinner flat area of the mentioned filler, not less than 5 µm and not more than 1000 µm, the problems mentioned before are surely solved. In addition, by not burying the material for holding the filler, the solar cell elements part are protected by the filler holding material, flow out of the filler can be prevented at an elevated temperature when the solar cell modules are laminated under vacuum and heat, the air remaining in the solar cell module can be exhausted to outside, and the problems causing deterioration of the solar cell module has been avoided including white turbidity of the folding part brought by peeling between the filler and the filler holding material and their cutting and the water flow therein. By the fact that the material for holding the filler is non-woven fabric or woven fabric, high light transmittance, high porosity and high strength have resulted. By these effects, flow out of the filler can be further prevented at an elevated temperature when the solar cell modules are laminated under vacuum and heat, the air remaining in the solar cell module is further exhausted to outside. Decrease of the incident light can be also kept to a minimum extent. By the fact that the non-woven fabric or woven fabric is ceramic non-woven fabric or woven fabric, glass non-woven fabric or woven fabric, or polypropylene non-woven fabric or woven fabric, high light transmittance, high porosity and high strength are secured. Thereby, enough protection against scratch and impact to the solar cell module results. With the high light transmittance, the incident light decreases by a minimum degree. Deterioration and discoloration for a long period of time are inhibited, and disadvantageous effects are prevented. Since the solar cell modules are not deteriorated when they are laminated under vacuum and heat, flow out of the filler is prevented at an elevated temperature in this process and the effect to exhaust the remaining air in the solar cell module outside is further enhanced. Furthermore, since the weather resistant film is a non-oriented film, elongation of the weather resistant film is large, and the problem of breaking weather resistant film in the step of folding is minimized. The non-oriented film also has accommodated the variation of filler from the thick part to the thin part, and cutting or wrinkling does not therefore occur even for a solar cell module in which the thickness varies significantly. Furthermore, since the back reinforcing plate is a metal plate, necessary strength as a structure and excellent workability have resulted. Excellent durability for outdoor use is secured thereby. Since metal plates have been conventionally used as roof materials, the convertibility therebetween is obtained. Due to the fact that the solar cell elements are bendable, the problem of crack in solar cell elements is avoided, and the thickness of solar cell module can be made thin since limited rigidity is required, which contributes to make the weight small and make the cost curtailed. Since the solar cell elements are amorphous silicon solar cell elements having, on a conductive substrate, a metallic electrode layer, amorphous silicon semiconductor layer, transparent conductive layer, and a grid electrode, thin solar cell elements can be manufactured inexpensively; less thick solar cell modules contributes reduction of the weight and cost. Since the solar cell elements are amorphous silicon solar cell elements connected in series with plural amorphous silicon solar cells that have, on a conductive substrate, a metallic electrode layer, amorphous silicon semiconductor layer, transparent conductive layer, and a grid electrode, manufacturing larger solar cell modules can be possible; thereby, array of solar cells with a broad area can be constituted with a smaller number of solar cell modules. Required parts and workmanship per module are consequently reduced and the cost is down. Since the folding is applied by using a roll molding machine, the fabrication can be continuos with high productivity, and the folding is possible in a shorter period and less expensively than the case where a bending machine with a receiver mold and blade is used. Thereby, molding shapes with complicated cross-section has become possible, and large and long modules can be manufactured simply. A solar cell module is provided which is excellent in folding workability and durability. The filler thickness in the suspended part 101, engagement part 103, rising part 104 and engagement part 105 of solar cell module 101 are made thinner than the filler that is placed other parts than these fold molded parts.

Claims: A method for manufacturing a solar cell module including the steps: preparing a solar cell module having a weather resistant film (305), solar cell elements (304), a filler (303) for burying the solar cell elements, and a back reinforcing plate (302), with the non-generating area of the solar cell module having a flat plane area; and applying folding to said flat plane area and said back reinforing plate by using a roll molding machine, characterized in that in said preparing step the filler (303) is applied to both the generating and non-generating area of the solar cell module and the thickness of the filler (303) is made thinner in the non-generating area of the solar cell module so that the generating area of the solar cell module represents a thick part and the non-generating area has a thin part to which said folding is applied. A method for manufacturing a solar cell module according to claim 1, characterized in that the thick part of said generating area and said thin part are formed such that the thick part and the thin part are connected through a gentle slope thickness part in a taper form. A method for manufacturing a solar cell module according to claim 1, characterized in that the filler thickness "a" in said thin part is set to meet a relation 5 ≤ a ≤ 100 µm. A method for manufacturing a solar cell module according to claim 1 to 3, characterized in that a material for holding the filler is buried in said filler (303) and said thin part does not have a buried material for holding the filler. A method for manufacturing a solar cell module according to claim 4, characterized in that said material for holding the filler is non-woven fabric or woven fabric. A method for manufacturing a solar cell module according to claim 5, characterized in that said non-woven fabric or woven fabric is ceramic non-woven fabric or woven fabric, glass non-woven fabric or woven fabric, or polypropylene non-woven fabric or woven fabric. A method for manufacturing a solar cell module according to claim 1, characterized in that said weather resistant film (305) is a non-oriented film. A method for manufacturing a solar cell module according to claim 1, characterized in that said back reinforcing plate (302) is a metal plate. A method for manufacturing a solar cell module according to claim 1, characterized in that said solar cell elements (304) are bendable. A method for manufacturing a solar cell module according to claim 1, characterized in that said thin part and the thick part of said generating area are formed with different fillers. A method for manufacturing a solar cell module according to claim 1, characterized in that said back reinforcing plate corresponding to said thin part (3002) is folded by using said roll molding machine so as to face the incident surface. A method for manufacturing a solar cell module according to claim 1, characterized in that said thin part is formed only in the part where said folding is planned. A method for manufacturing a solar cell module according to claim 1 or 12, characterized in that said folding is made by using said roll molding machine, a mold and a blade. A method for manufacturing a solar cell module according to claim 1, characterized in that the end part (3410) of the solar cell module is formed by exposure of the back reinforcing plate (3402). A solar cell module comprising a weather resistant film (305), solar cell elements (304), a filler (303) for burying the solar cell elements, and a back reinforcing plate (302), with the non-generating area of the solar cell module being folded, characterized in that the filler (303) is applied to both the generating and non-generating area of the solar cell module and the thickness of the filler (303) is thinner in the non-generating area of the solar cell module so that the generating area of the solar cell·module represents a thick part and the non-generating area has a thin part to which said folding is applied. A solar cell module according to claim 15, characterized in that the thick part of said generating area is connected to said thin part through a gentle slope thickness part in a taper form. A solar cell module according to claim 15, characterized in that the filler thickness "a" in said thin part meets a relation 5 ≤ a ≤ 1000 µm. A solar cell module according to one of claims 1 to 17, characterized in that a material for holding the filler is buried in said filler (303) and said thin part does not have a buried material for holding the filler. A solar cell module according to claim 18, characterized in that said material for holding the filler is non-woven fabric or woven fabric. A solar cell module according to claim 19, characterized in that said non-woven fabric or woven fabric is ceramic non-woven fabric or woven fabric, glass non-woven fabric or woven fabric, or polypropylene non-woven fabric or woven fabric. A solar cell module according to claim 15, characterized in that said weather resistant film (305) is a non-oriented film. A solar cell module according to claim 15, characterized in that said back reinforcing plate (302) is a metal plate. A solar cell module according to claim 15, characterized in that said solar cell elements (304) are bendable. A solar cell module according to claim 15, characterized in that said solar cell elements (304) are amorphous silicon solar cell elements (1300) that have, on a conductive substrate (1201), a metallic electrode layer (1202), an amorphous silicon semiconductor layer (1203), a transparent conductive layer (1204), and a grid electrode (1302). A solar cell module according to claim 24, characterized by plural amorphous silicon solar cell elements (1501, 1502, 1503) connected in series. A solar cell module according to claim 15, characterized in that said thin part and the thick part of said generating area are formed with different fillers. A solar cell module according to claim 15, characterized in that said back reinforcing plate corresponding to said thin part (3002) is molded by folding so as to face the incident surface. A solar cell module according to claim 15, characterized in that said thin part is formed only in the folded part. A solar cell module according to claim 15, characterized in that said back reinforcing plate (3402) is exposed at the end part (3410) of the solar cell module.

Inventors: FUKAE KIMITOSHI, INOUE YUJI, OHTSUKA TAKASHI, FUKAE, KIMITOSHI, INOUE, YUJI, OHTSUKA, TAKASHI, FUKAE, KIMITOSHI, C/O CANON K.K., INOUE, YUJI, C/O CANON K.K., Ohtsuka, Takashi, c/o Canon K.K.
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1995
Main classification: H01L31
IPC codes: H01L31, E04D13