JP3838684B2 - Method for manufacturing flexible solar cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a flexible solar cell in which one or a plurality of thin-film solar cell elements having a flexible substrate are sandwiched by a common surface holding material.
[0002]
[Prior art]
Both sides of a solar cell submodule in which a plurality of thin film solar cells formed by laminating a back electrode layer, a photoelectric conversion semiconductor layer, and a transparent electrode layer on a flexible substrate such as a polymer material film are connected by connecting wires, It is known, for example, in Japanese Patent Publication No. 5 (1993) -59591, that it is protected from the influence of moisture and gas of the outside air by coating with a protective material. FIG. 3 shows a cross-sectional structure of such a flexible solar cell, using a glass plate 31 on the front side and a fluororesin film 32 on the back side as a surface protective material, and a plurality of thin film solar cells on the flexible substrate. The solar cell submodule 1 in which the element is formed is sealed through ethylene vinyl acetate (EVA) 2 as an insulating sealing material. Further, the sides are covered with an aluminum frame 33 and a silicone resin sealant material 34 for reinforcement.
[0003]
The manufacturing process of the solar cell module as described above includes a step of arranging a plurality of solar cell submodules 1 on the surface protection material 31 and the film-like EVA 2 stacked in a single sheet, and performing wiring work, A film-like EVA 2 and a back surface protective material 32 are sequentially laminated on the solar cell submodule 1 after work in a single sheet, and this is thermocompression-bonded under reduced pressure to cross-link the EVA 2. It consists of a step of covering the periphery with the frame 33 and filling the gap with the sealant 34. Thermocompression bonding / crosslinking under reduced pressure is performed by first raising the temperature of EVA2 to a temperature at which the melt viscosity of EVA2 is lowest and no crosslinking reaction occurs in the sealing material while evacuating the atmosphere of the laminated material. After the pressure is maintained for a certain period of time, in order to cross-link EVA2, the temperature is raised to the optimum cross-linking reaction temperature and held.
[0004]
Thin-film solar cell using the flexible substrate, since it is possible to wind a film of multiple layers in a roll-to-roll or stepping roll method on an elongated substrate to be pulled out from the roll, in terms of mass production It is excellent. However, in the method of manufacturing a single-wafer solar cell module as described above, mass productivity, which is one of the characteristics of the flexible solar cell, is not lost, and the product is stored in a compact state wound in a roll shape. Further, it is impossible to make use of another characteristic of the flexible solar cell that can be moved and installed. Therefore, if a flexible weather-resistant material film is used as the protective material on both sides, all the module constituent materials can be drawn from the roll, and the completed module can be continuously wound on the roll. It is also conceivable that the surface protective material is omitted to make it flexible, and the EVA layer is exposed and protected by the weather resistance of EVA.
[0005]
[Problems to be solved by the invention]
However, in order to continuously seal the solar cell element and wind it into a roll, it is necessary to continuously supply the module constituent material from a state wound in a roll. Among module components, EVA used as an insulating sealing material can be wound in a roll shape, but the material itself stretches so that it does not cause dimensional change or deflection while controlling tension. Have the problem of not being able to. Moreover, since it melts at the time of thermocompression bonding, it is difficult to continuously convey the insulating sealing material at a constant speed. For this reason, in the process of laminating and pressure-bonding the solar cell element, the surface protection material, and the wiring material, wrinkles and bubbles are involved, and the reliability of the solar cell module is also lowered. Such a problem also exists when a single thin-film solar cell element is sealed.
[0006]
The object of the present invention is to solve the above-mentioned problems and to enable drawing of constituent materials from rolls and winding after sealing without causing dimensional changes, wrinkles and deflections due to melting of the insulating sealing material. Another object of the present invention is to provide a method for manufacturing a flexible solar cell.
[0007]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention provides a flexible solar cell manufacturing method in which a solar cell element formed on a flexible substrate is sealed with an insulating sealing material. After pressure-bonding between the flexible support base and one surface of the opposing body having a surface layer made of a releasable material on at least one surface, the opposing body is removed to expose the insulating sealing material. And a step of bringing the insulating sealing material exposed surface on the supporting substrate into contact with the solar cell element and then crimping the insulating sealing material on the supporting substrate to both surfaces of the solar cell element. Among the steps of performing the pressure bonding, the step performed later is the step of thermocompression bonding under reduced pressure.
By supporting the insulating sealing material by pressing it on a flexible support substrate, it can be conveyed together with the sealing material thereon by controlling the tension of the support substrate. Since the dimensional change and the deflection of the sealing material do not occur at the time of pulling out from the roll, it is possible to perform the crimping process to the solar cell element between the pulling out from the roll and the winding onto the roll. When a pressurizing body for pressure bonding comes into contact with the insulating sealing material, it adheres to the pressurizing body and is not easily separated, and therefore pressure is applied through a counter body having a releasable surface. Thereafter, the opposing body is removed so that the insulating sealing material can be brought into contact with the solar cell element. Of the steps of contacting and pressing the insulating sealing material on the support base to both sides of the solar cell element, the step performed later is the step of thermocompression bonding under reduced pressure, and thermocompression bonding is performed under reduced pressure. Accordingly, the gas released from the constituent material and the air entrained in the constituent material in the previous process are removed, and the adhesion of the sealing material to the solar cell element is ensured. The insulating sealing material is preferably made of EVA. EVA has a track record as a sealing resin. In that case, it is desirable that the pressure bonding be performed at 120 ° C. or lower and the crosslinking be performed in a later step. If it is 120 ° C. or higher, a crosslinking reaction occurs. The cross-linking reaction is performed for a necessary time in a separate step. It is preferable that the support base of the insulating sealing material is made of a releasable material and includes a step of removing the support base after the step of pressure-bonding the insulating sealing material to the solar cell element. As a result, a flexible solar cell having both surfaces sealed with an insulating material is completed . The releasable material is preferably a fluorine resin, a silicone resin, or a metal oxide. These materials have a surface free energy lower than that of plastic used for the supporting substrate, and therefore have a low adhesion to sealing materials and dust.
According to the reference means of the present invention, the supporting substrate of the insulating sealing material is made of a material having weather resistance, and at least the pressure-bonding surface with the insulating sealing material has low releasability, and the entire manufacturing process It is desirable to leave it after the end. As a result, the support base remains as a surface protective material and is fixed to the insulating sealing material with sufficient adhesive strength. It is preferable to provide a step of performing an adhesion improving surface treatment on the sealing material pressure-bonding surface of the support base of the insulating sealing material before pressure bonding. Thereby, the adhesive strength with the insulating sealing material of a surface protection material improves. A step of coating the surface layer made of a releasable material on the anti-sealing material pressure-bonding surface of the support base of the insulating sealing body may be provided. As a result, adhesion of dust and the like to the surface protection material is reduced, and the incident light is not reduced particularly on the light incident surface side.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The flexible solar cell is composed of a solar cell element, a main wiring material, an auxiliary wiring material, an insulating sealing material, and, in some cases, a surface protective material. One solar cell element or a plurality of solar cell elements may be modularized.
A thermoplastic resin made of EVA is used as the material of the insulating sealing material. EVA is a hot-melt adhesive material having a melting point at 60 to 80 ° C. at which the melt viscosity rapidly decreases at a temperature of 50 ° C. or higher. Note that the melt viscosity does not change significantly in the range of 60 ° C. to 150 ° C., and tends to have a lower melt viscosity as the temperature increases. Further, EVA has a characteristic that, in a temperature range of 120 ° C. or higher, the reaction rate varies depending on the temperature, but a crosslinking reaction is caused by a crosslinking material mixed in advance in EVA and is thermally stabilized. On the other hand, regarding the fusion property of EVA, when fusion is performed under a constant pressure, the fusion force changes depending on the temperature and time. The higher the temperature and the longer the fusion strength, the greater the fusion strength. growing. For this reason, as thermocompression bonding conditions for EVA, when thermocompression bonding and cross-linking are continuously performed, it is desirable to perform at a temperature of 60 ° C to 120 ° C. The EVA crosslinking conditions must be maintained at a temperature of 140 to 150 ° C. for 10 to 15 minutes as a condition that enables EVA to be sufficiently gelled.
[0009]
At least the surface of the support base used for the purpose of fixing and supporting the insulating sealing material, which is removed in a subsequent process, should have a releasability. Therefore, fluororesin films such as polyvinyl fluoride (PVF) and tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), fluororesin coating, silicone resin coating, polyethylene and polyolefins with SiOx surface film formed Use film or metal foil. The supporting substrate of the insulating sealing material, which is not removed in a subsequent process and remains as a surface protective material, must exhibit good adhesion to EVA of the insulating sealing material. As such a supporting substrate, a polyester film such as polyethylene terephthalate (PET) having low releasability, a polyvinyl alcohol film, a polyvinyl chloride film, a polyvinylidene chloride film, a polyimide film or a polyethylene film can be used. Furthermore, in order to increase the adhesive strength with EVA, the adhesive surface is subjected in advance to a physical surface treatment such as plasma treatment or ultraviolet irradiation, or a chemical surface treatment such as coupling agent treatment, monomer or polymer coating treatment, or steam treatment. The surface tension is set to 40 dyne / cm or more. In addition, on the opposite outer surface, the solar cell is protected from external forces during storage, movement, installation and operation, prevention of contamination of the light incident surface due to dust adhesion, etc. Fluorine resin coating or silicone resin coating is applied to prevent electric shock. Alternatively, a film of a material having releasability may be simply attached. Of the supporting substrate remaining as the surface protective material, the light incident side needs to be a transparent film that transmits visible light. Cu, Ag or Al as the conductive material is used for the main wiring material and the auxiliary wiring material of the wiring material. The shape may be a foil or a twisted line. In that case, it is convenient to use a conductive adhesive layer formed on one side or both sides. For the connection between the external terminals of the entire flexible solar cell and the auxiliary wiring or the main wiring, a conductive foil having a conductive adhesive layer on the surface is used, or a conductive adhesive or solder is used.
[0010]
Note that the pressure bonding or thermocompression bonding is performed in order to make EVA adhere to the solar cell element. Therefore, it does not necessarily mean that pressure is applied from the outside, and includes a case where pressure is applied to the contact surface between the EVA and the element due to its own weight.
[0011]
【Example】
Hereinafter, several embodiments of the present invention will be described with reference to the drawings including the same reference numerals in FIG.
Example 1:
1A to 1F show the manufacturing process of Example 1, and FIG. 2 shows the manufacturing apparatus used in this process. The manufacturing process consists of seven steps from step 1 to step 7.
<Step 1>
As shown to Fig.1 (a), it bonds together to the fluororesin coating film 3 which has a release property on both surfaces of the film of EVA2 which is an insulating sealing material. For that purpose, as shown in FIG. 2, the EVA film 2 drawn out from the roll 11 and the two fluororesin coating films 3 drawn out from the two rolls 12 are thermocompression bonded through the two pressure-bonding rolls 13. The thermocompression bonding is performed at a temperature of the thermocompression-bonding roll 13 of 120 ° C. or less so that the crosslinking material in EVA is not consumed or the effect as the crosslinking material is not lost. Since fluorine coating film 3 of the upper surface is intended to prevent the EVA2 from adhering to the surface of the roll 13 is peeled off before entering the next step taken up into a roll 22, the film 3 of the release of the supporting base member A base film 4 on which the EVA layer 2 is fixed is obtained.
<Step 2>
As shown in FIG. 1 (b), the main wiring member 5 is fixed on the EVA layer 2 of the base film 4. The main wiring 5 is drawn from the roll 14 with its longitudinal direction parallel to the longitudinal direction of the base film 4 and is crimped or thermocompression bonded by the crimping roll 15. Since the fixing surface of the main wiring member 5 is a part of the base film 4, the main wiring member 5 itself is heated when thermocompression bonding is performed. One of the two main wiring members 5 in the figure is the plus side, and the other is the minus side.
<Step 3>
As shown in FIG. 1 (c), a solar cell sub-module 1 made of a solar cell element is fixed to a predetermined position on the EVA layer 2 on the base film 4 with a single sheet, and is crimped or thermocompression bonded through a crimping roll 16. . The conditions for thermocompression bonding are the same as in step 1.
[0012]
The positional relationship between the solar cell submodule 1 and the main wiring member 5 is arranged such that the positive and negative terminals of the solar cell submodule 1 overlap the main wiring member 5 or the main wiring member with respect to the solar cell submodule 1. 5 is placed outside. However, since a part of the main wiring member 5 is outside the peripheral edge of the module 1 and is electrically connected to the outside, a phenomenon that deteriorates the reliability of the solar cell module such as peeling or corrosion is caused by the main wiring member 15. Since it can be said that the portion is most likely to occur, a positional relationship in which the main wiring member 5 is outside the submodule 2 as shown in the drawing is more desirable.
<Step 4>
As shown in FIG. 1 (d), the connection between the solar cell submodule 1 and the main wiring member 5 is performed by the auxiliary wiring member 51. The dimensions and supply position of the auxiliary wiring member 51 differ depending on the positional relationship between the solar cell submodule 1 and the main wiring member 5. Of course, the dimensions and supply position relationship must overlap at least partially. <Step 5>
Although not shown in FIG. 1 (e), a base film produced separately by peeling the film on the lower surface after laminating the fluororesin coating film 3 on both sides of the film-like EVA 2 through the thermocompression roll 13 4 are stacked so that the EVA layer 2 is in contact with the solar cell module 1, and thermocompression-bonded by a pressure-bonding roll 17. When the pressure bonding is performed in an atmospheric pressure atmosphere, air bubbles are likely to be generated due to air entrainment at the stepped portion of the solar cell module 1 or gas released from the constituent material. For this reason, it is most desirable to provide a decompression chamber (not shown) and perform thermocompression bonding with the heating roll 13 under reduced pressure. At this time, bubbles and wrinkles generated in step 1 are also removed. In this case as well, the process is performed at a temperature of 120.degree. There is a method of performing thermocompression bonding with a heated flat plate, but it is inferior in terms of mass productivity.
<Step 6>
Next, as shown in FIG. 2, EVA 2 is cross-linked through the heating chamber 18.
[0013]
It is necessary to maintain the crosslinking conditions at a temperature of 140 to 150 ° C. for 10 to 15 minutes as a condition that enables sufficient gelation of EVA. Since the crosslinking temperature is higher than the thermocompression bonding temperature, it is desirable to depressurize the heating chamber 18 because there is gas emission from the constituent material of the flexible solar cell module. Further, since EVA has a melt viscosity that is lowered at a temperature of 50 ° C. or higher, it is desirable that EVA be further crosslinked in a pressurized state in order to prevent molding defects.
<Step 7>
Finally, as shown in FIG. 2, the double-sided releasable fluororesin coating film 3 is peeled off after passing through the roll 19 to form a flexible solar cell 10 having the structure shown in FIG. Wind up. The peeled fluororesin coating film 3 is wound around two rolls 21.
Example 2:
In this embodiment, as shown in FIGS. 4A to 4D, Step 2 and Step 3 of Embodiment 1 are interchanged. Therefore, also in the roll-to-roll module assembly apparatus, as shown in FIG. 5, the delivery roll 14 and the crimping roll 15 of the main wiring member 5 are arranged behind the crimping roll 16 of the solar cell submodule 1. As a result, the solar cell submodule 1 is fixed on the EVA layer 2 of the base film 4 as shown in FIG. 4B, and then the main wiring member 5 is placed outside the submodule 1 as shown in FIG. Then, as shown in FIG. 4D, the connection between the submodule 1 and the main wiring member 5 is performed by the auxiliary wiring member 51. The subsequent steps are the same as those shown in FIGS.
Example 3:
Used as the supporting base of the releasing in Step 1 and 5 in Example 1 or Example 2, in place of the fluorine resin coating film 3 peeled off in a later step, little releasability as shown in FIG. 6 PET A base film 41 is formed using the film 6 as a support base of EVA2. This PET film 6 is pulled out from the roll 12 by the apparatus shown in FIG. 2 or FIG. 5, and the film-like EVA 2 is fixed thereon. However, on the other surface of the EVA 2, a fluororesin coating film 3 having releasability similar to that in Example 1 or Example 2 is bonded, and the EVA 2 and the PET film 6 are peeled off after thermocompression bonding. Then, Step 7, that is, the rolls 19 and 21 in FIG. 2 or 5 are omitted, and the flexible solar cell module 10 formed by fixing the base film on both sides is finished with the EVA 2 in the heating chamber 18. Directly on the roll 20. The PET film 6 that has not been peeled off is left as a surface protective material.
Example 4:
Instead of the PET film 6 of Example 3, a film in which the surface in contact with EVA 2 has been subjected to surface treatment for improving adhesion in advance is used. That is, a polyvinyl alcohol (PVA) film subjected to plasma treatment as a surface treatment for improving adhesion is used.
Example 5:
Instead of the PET film 6 of Examples 3 and 4, a polyethylene film is used. A fluorine resin coating is applied to the surface of the polyethylene film opposite to the EVA side. This prevents dust and the like from adhering to the surface, and is particularly effective on the light incident surface side.
[0014]
【The invention's effect】
According to the present invention, by fixing the insulating sealing material for covering the solar cell element on the support base, it is possible to carry the tension control when pulling out from the roll to the support base. became. As a result, the flexible solar cell was sealed using the constituent material supplied from the state wound on the roll, and the manufacturing process of winding on the roll was realized. And high mass productivity was obtained compared with the single wafer system, and it became possible to manufacture a flexible solar cell module that can be stored, moved, and constructed in a particularly compact state.
[Brief description of the drawings]
1 is a cross-sectional view showing the manufacturing process of Example 1 of the present invention in the order of (a) to (f). FIG. 2 is a side view of a manufacturing apparatus for performing the manufacturing process shown in FIG. FIG. 4 is a cross-sectional view showing the first half of the manufacturing process of Example 2 of the present invention in the order of (a) to (d). FIG. 5 is a cross-sectional view of a manufacturing apparatus for performing the manufacturing process shown in FIG. Side view [FIG. 6] Cross-sectional view of the base film used in Examples 3 to 5 of the present invention [Explanation of symbols]
1 Solar cell sub-module 2 EVA
DESCRIPTION OF SYMBOLS 3 Fluorine resin coating film 4, 41 Base film 5 Main wiring material 51 Auxiliary wiring material 6 PET film 10 Flexible solar cell module 13, 15, 16, 17 Crimp roll 18 Heating chamber

Claims (5)

In a method for manufacturing a flexible solar cell in which a solar cell element formed on a flexible substrate is sealed with an insulating sealing material, the insulating sealing material is provided on at least one surface with a flexible support base. A step of pressure-bonding between the opposing body having a surface layer made of a releasable material and then removing the opposing body to expose the insulating sealing material; A step of bringing the exposed surface of the conductive sealing material into contact with the solar cell element and press-bonding the insulating sealing material on the support substrate and bringing the insulating sealing material on both sides of the solar cell element into contact with the solar cell element. method for producing a flexible solar cell dividing process is characterized a step der Turkey thermocompression bonding under reduced pressure. The flexible solar cell according to claim 1 , further comprising a step of removing the support base after the step of pressure-bonding the insulating sealant to the solar cell element, wherein the support base of the insulating sealant is made of a releasable material. A battery manufacturing method. The method for manufacturing a flexible solar cell according to claim 1, wherein the insulating sealing material is made of ethylene vinyl acetate . The method for producing a flexible solar cell for a solar cell according to claim 3, wherein the pressure bonding is performed at 120 ° C. or less, and the crosslinking is performed in a later step . The method for producing a flexible solar cell according to any one of claims 1 to 4 , wherein the releasable material is a fluorine resin, a silicone resin, or a metal oxide .

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