JP2001060706A - Method for manufacture of solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need for trimming a protective film to be used while protecting a heater against contamination with sealing resin at the time of reheating by setting the size of a sealing resin sheet larger than that of a glass substrate by an amount corresponding to shrinkage of the sealing resin due to curing. SOLUTION: A solar cell sub-module 20 comprising a plurality of cells 120 integrated on a glass substrate 11 is sealed using a vacuum laminator 30. A sealing resin sheet 13 has a size larger than that of the substrate 11 by an amount corresponding to shrinkage thereof and a protective film 14 has the same size as the substrate 11. A laminate of the sheet 13 and the film 14 is mounted on the rear surface of the solar cell sub-module 20 in the vacuum laminator 30, pressure in the upper and lower chambers 31, 32 thereof are then reduced and the laminate is pressed while being heated by means of a heater 323. The laminate is taken out from the vacuum laminator 30 before the sealing resin is cured and then heated again by means of another heater thus finishing curing of sealing resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a solar cell module by sealing a solar cell sub-module with a protective film via a sealing resin.

[0002]

2. Description of the Related Art A non-single-crystal solar cell made of amorphous silicon or the like has a higher degree of freedom in selecting a substrate than a crystalline solar cell, and can be easily formed on a translucent (transparent) glass substrate at a relatively low temperature. It has the feature that it can be formed in. In general, an amorphous solar cell is a so-called amorphous solar cell in which a plurality of solar cell unit cells including a transparent front electrode layer, a non-single-crystal photoelectric conversion unit and a back electrode layer are formed on a transparent glass substrate, and these are electrically connected to each other. It is configured as a solar cell sub-module. In order to physically or chemically protect each unit cell including its back electrode layer, such a solar cell sub-module is protected by a protective film via a sealing resin on its back side, so-called solar cell sub-module. It has been commercialized as a module.

[0003] Conventionally, protection (sealing) of a solar cell sub-module by a protective film has been performed by using a sealing resin (for example, ethylene / ethylene mixed with a curing agent) on the back surface of the solar cell sub-module.
This has been performed by placing a sheet of vinyl acetate copolymer), placing a protective film thereon, and heat-pressing the sealing resin sheet and the protective film to the back surface of the solar cell sub-module. In the heat-press bonding process, the sealing resin is cured through softening and melting. After the curing of the sealing resin, the excess protective film and the like are trimmed and removed.

Conventionally, the sealing of a solar cell sub-module with a sealing resin sheet / protective film is performed by using a vacuum laminating apparatus for the purpose of preventing air bubbles from being mixed therein. The process from softening / melting to the end of curing was continuously performed in the same vacuum laminating apparatus. However, the vacuum laminating apparatus has no processing capacity to seal a plurality of solar cell sub-modules at once, and is very expensive. Therefore, in recent years, the solar cell sub-module has been transferred from the vacuum laminating apparatus to the oven during the curing at the end of melting of the sealing resin without performing the heat-compression treatment until the completion of the curing of the sealing resin in the vacuum laminating apparatus. Completing the curing of the sealing resin is being performed. The trimming is performed after the curing of the sealing resin is completed.

[0005]

However, since the sealing resin is heated by the vacuum laminating apparatus and is in a flowing state at the melting stage, it flows out of the glass substrate region. If the solar cell sub-module is reheated for curing in an oven with this melt-extended portion, the melt-extended portion (extended portion) of the sealing resin may fall off and contaminate the oven. all right. This contamination of the oven reduces the productivity of the solar cell module since the oven requires cleaning.

Accordingly, it is an object of the present invention to provide a method for efficiently manufacturing a solar cell module without preventing contamination of a heating device such as an oven and reducing productivity.

[0007]

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, the resin used as a sealing resin, which is cured through melting by heating, shrinks to a certain degree upon curing. We paid attention to it. By setting the size of the sealing resin sheet to a size larger than the glass substrate by the amount of the curing shrinkage, even if the sealing resin is heated and melted, the amount of the resin extending from the glass substrate is small, if any. Therefore, even if the sealing resin is reheated in an oven to complete the curing, the sealing resin does not cause contamination of the oven, and shrinks during curing to a certain extent. Was found to be substantially equal to the size of the glass substrate. in this way,
Since the size after curing of the sealing resin is substantially equal to the size of the glass substrate, if the size of the protective film is set to be substantially equal to the size of the glass substrate from the beginning,
It turned out that trimming of a protective film etc. is unnecessary. The present invention is based on these findings.

That is, the present invention provides a sheet of a sealing resin which can be cured through softening / melting by heating on the back surface of a solar cell sub-module having a plurality of unit cells integrated on the back surface of a translucent glass substrate. And a protective film,
A step of pressing the sealing resin sheet and the protective film and the solar cell sub-module in a vacuum heating and pressing apparatus while heating them under vacuum, and pressing the solar cell sub-module under the vacuum heating and pressing during the curing of the sealing resin. After taking out from the device, including a step of completing the curing of the sealing resin under heating in another heating device, the sealing resin sheet placed on the back surface of the solar cell sub-module, the sealing resin Has a size larger than the size of the glass substrate by the amount of shrinkage upon curing, and the protective film placed on the sealing resin sheet has a size substantially equal to the size of the glass substrate. To provide a method for manufacturing a solar cell module.

In the present invention, it is preferable that the peripheral portion of the sealing resin sheet (melt of the sealing resin) except for the central portion is kept unbound during heating by another heating device. Thereby, the curing shrinkage of the sealing resin is freely performed. At this time, by temporarily fixing the protective film by heat at the center thereof, it is possible to prevent the protective film from shifting.

In the present invention, the sealing resin is preferably made of an ethylene / vinyl acetate copolymer containing a curing agent, and the protective film preferably contains an organic fluororesin film.

In the present invention, it is preferable that the vacuum heat compression is performed at a temperature of about 120 ° C. to about 130 ° C. for about 5 minutes to about 10 minutes.
It is preferably performed at a temperature of 40 ° C. or higher for about 10 minutes to about 120 minutes.

In this specification, the light incident side is called a front surface, and the opposite side is called a back surface.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. Throughout the figures, similar elements
The same reference numerals are used.

As described above, the present invention relates to a method for manufacturing a solar cell module by sealing a solar cell sub-module with a sealing resin / protective film laminate. First, an example of a solar cell module manufactured according to the present invention will be described with reference to FIG.

The solar cell module 10 shown in FIG. 1 includes a solar cell sub-module having a plurality of solar cell unit cells 12 integrated on a translucent (transparent) glass substrate 11. This solar cell sub-module is a glass substrate 11
Light enters from the side.

Each unit cell 12 includes, in order from the glass substrate 11, a transparent front electrode layer 121, a non-single-crystal silicon-based photoelectric conversion unit 122, and a back electrode layer 123.

The transparent front electrode layer 121 formed on the glass substrate 11 can be composed of a transparent conductive oxide layer such as an ITO film, a SnO ₂ film, or a ZnO film. The transparent front electrode layer 121 may have a single-layer structure or a multilayer structure, and any of them can be formed by a known vapor deposition method such as an evaporation method, a CVD method, and a sputtering method. It is preferable that the surface of the transparent front electrode layer 121 has a surface texture structure including fine irregularities.
By forming such a texture structure on the surface of the transparent front electrode layer 121, light incident on the non-single-crystal silicon-based photoelectric conversion unit 122 is emitted to the outside of the cell 12 without contributing to photoelectric conversion. Can be suppressed.

Normally, non-single-crystal silicon-based photoelectric conversion units 122 formed on transparent front electrode layer 121 are not shown, but are p-type non-single-crystal silicon-based semiconductors formed on transparent front electrode layer 121. And a non-single-crystal silicon-based thin film photoelectric conversion layer and an n-type non-single-crystal silicon-based semiconductor layer. All of these p-type semiconductor layers, photoelectric conversion layers, and n-type semiconductor layers can be formed by a plasma CVD method. The p-type silicon-based semiconductor layer can be formed of silicon or a silicon alloy such as silicon carbide or silicon germanium, and is doped with a p-conductivity determining impurity atom such as boron or aluminum. The photoelectric conversion layer formed on the p-type semiconductor layer is formed of a non-single-crystal silicon-based semiconductor material. Examples of such a material include silicon (e.g., silicon hydride) as an intrinsic semiconductor, silicon carbide, and silicon germanium. Silicon alloys and the like are included. If the photoelectric conversion function is sufficiently provided, a weak p-type or weak n-type silicon-based semiconductor material containing a trace amount of impurities for determining conductivity type can also be used. When this photoelectric conversion layer is amorphous, it is usually formed to a thickness in the range of 0.1 to 10 μm. The n-type silicon-based semiconductor layer formed over the photoelectric conversion layer can be formed of silicon or a silicon alloy such as silicon carbide or silicon germanium, and is doped with an n-conductivity determining impurity atom such as phosphorus or nitrogen. .

The back electrode 123 formed on the upper photoelectric conversion unit 122 is formed of a metal material. The back electrode layer 122 not only has a function as an electrode, but also has a function of transferring from the glass substrate 11 to the photoelectric conversion unit 122. The incident light that reaches the back electrode layer 123 is reflected to reflect the light into the photoelectric conversion unit 1.
Since it is preferable to also have a function as a reflection layer for re-entering the light into the inside 22, it is preferable to use a metal material having high light reflectance such as a silver-based material such as silver or silver alloy. The back electrode layer 123 can be formed by an evaporation method, a sputtering method, or the like.

The transparent front electrode layer 121 and the non-single-crystal silicon-based photoelectric conversion unit 122 described above are formed on the glass substrate 11 as a large-area thin film, and then divided into a plurality of thin films using laser processing or the like. And a plurality of unit cells 1
2 are formed simultaneously. These plurality of unit cells 12
They are electrically connected in series or in parallel to form an integrated structure.

As shown in FIG. 1, the peripheral region 111 of the glass substrate 11 is made of a transparent front electrode thin film, a silicon thin film, etc., which are deposited for the production of the cell 12 by means such as sandblasting. It has been removed, exposing the glass surface. Since the glass surface is exposed in the peripheral region of the glass substrate 11 as described above, the adhesive strength with the sealing resin described later is improved.

The back surface of the solar cell submodule described above is protected and sealed by a protective film 14 via a sealing resin layer (adhesive layer) 13.

The sealing resin used in the present invention is a resin which can be cured by being softened and melted by heating. The sealing resin seals each unit cell formed on the glass substrate 11 and firmly fixes the protective film 14. It is a resin that can be bonded. Examples of such resins include, for example, heat of ethylene / vinyl acetate copolymer (EVA), ethylene / vinyl acetate / triallyl isocyanurate (EVAT), polyvinyl butyral (PVB), and polyisobutylene (PIB). EVA is a plastic resin, and is preferably EVA from the viewpoint of adhesiveness to the glass substrate 11 and cost. Needless to say, a curing agent (crosslinking agent) is blended with these thermoplastic resins in order to crosslink and cure them. Preferred examples of such a curing agent include organic peroxides such as 2,5-dimethylhexane-2,5-dihydroperoxide. The organic peroxide cross-linking agent may generate radicals when heated to a temperature of 100 ° C. or higher to cross-link the sealing resin.

The protective film 14 protects the solar cell submodule placed in an outdoor environment, and is preferably excellent in moisture resistance and water resistance, and is preferably insulating. Such a protective film 14 is made of a fluororesin film such as a polyvinyl fluoride film (for example, Tedlar film (registered trademark)) or polyethylene terephthalate (PE).
T) What is necessary is just to have an organic film such as a film on the side in contact with the sealing resin layer 13, and may have a single-layer structure or a laminated structure of the organic film. further,
The protective film 14 may have a structure in which a metal foil made of aluminum or the like is sandwiched between these organic films. Since a metal foil such as an aluminum foil has a function of improving moisture resistance and water resistance, by using the protective film 14 having such a structure, the back surface of the solar cell sub-module can be more effectively protected from moisture. Can be. As the organic film, a fluororesin film is preferable.

Next, an example of a method for manufacturing a solar cell according to the present invention will be described with reference to FIGS. In addition, FIG.
4, the integrated structure of the solar cell unit cells 12 described with reference to FIG.

First, according to the present invention, the sealing resin sheet and the protective film are placed on the back surface of the solar cell sub-module, and the sealing resin sheet is placed in a vacuum heating / compression bonding apparatus (a so-called vacuum laminating apparatus). Then, the protective film and the solar cell sub-module are pressure-bonded while heating under vacuum.

As the vacuum laminating apparatus to be used, a known apparatus such as a double vacuum laminating apparatus can be used. For example, the vacuum laminating apparatus 30 illustrated in FIG. 2A includes a lower chamber 32 and an upper chamber 31 that is opened and closed by a driving mechanism (not shown) with respect to the lower chamber 32.

The upper chamber 31 has a diaphragm 311 having a peripheral portion hermetically fixed to an inner peripheral wall of the upper chamber 31.
Is provided. An upper exhaust hole 312 communicating with a space separated by the diaphragm 311 is formed on one side wall of the upper chamber 31.
An exhaust suction pump (not shown) is connected to 12.
On the other hand, a mounting plate 321 on which the object to be laminated is mounted is provided in the lower chamber 32, and a heater 323 for heating at the time of lamination is built therein. Further, a lower exhaust hole 3 is provided on one side wall of the lower chamber 32.
The lower exhaust hole 322 is connected to an exhaust pump (not shown).

In order to seal the solar cell sub-module 20 including the plurality of cells 120 integrated on the glass substrate 11 using the vacuum laminating apparatus 30, first,
As shown in FIG. 2A, the glass substrate 11 is
The solar cell sub-module 20 is mounted on the mounting board 321 in the lower chamber 32 so as to be in contact with 1. Next, a sealing resin sheet 13 ′ is placed on the back surface (the top surface in FIG. 2A) of the solar cell sub-module 20, and a protective film 14 is placed thereon, thereby forming a laminated body.

As shown in FIG. 2B, the sealing resin sheet 13 'has a size larger than the size of the glass substrate 11 by an amount corresponding to the curing shrinkage. Here, the fact that the sealing resin sheet 13 ′ has a size larger than the size of the glass substrate 11 by an amount corresponding to the curing shrinkage means that after the sealing resin sheet 13 ′ is subjected to heat and pressure in the vacuum laminating apparatus, it will be described in detail hereinafter. As described above, after being subjected to a heat treatment for completing the curing by another heating device, for example, FIG.
As shown in FIG.
1 has a size that is substantially flush with the peripheral end face. The size of the sealing resin sheet 13 'can be calculated based on, for example, an experimentally determined shrinkage ratio when the sealing resin sheet is cured.

Further, in the present invention, the protective film 14
Has a size substantially equal to the size of the glass substrate 11, as also shown in FIG. Here, that the protective film 14 has a size substantially equal to the size of the glass substrate 11 means that the protective film 14 adheres via the layer 13 of the sealing resin which has been cured through softening and melting according to the present invention. This means that the protective film 14 has a size such that the peripheral end surface of the protective film 14 is substantially flush with the peripheral end surface of the glass substrate 11 (see FIG. 1).

Returning to FIG. 2A, as described above, after the sheet 13 'of sealing resin and the protective film 14 are mounted on the back surface of the solar cell sub-module 20, a laminated body is formed. The upper chamber 31 is closed with respect to the lower chamber 32, and the pressure in the upper chamber 31 and the lower chamber 32 is reduced to remove a gas that may be contained in the sealing resin sheet 13 ′. Then
As shown in FIG. 2A, the diaphragm 311 provided in the upper chamber 31 expands downward and comes into pressure contact with the object to be laminated mounted on the mounting plate 321 heated by the heater 323. Thus, the object to be laminated is the mounting plate 32.
The sealing resin sheet 13 ′ is softened and melted by being heated and pressed by the diaphragm 111 and the diaphragm 311, resulting in adhesion between the protective film 14 and the back surface of the solar cell sub-module 20,
A laminate is provided.

However, in the present invention, the heat and pressure bonding (lamination) by the vacuum laminating apparatus 30 is performed.
Is terminated during the curing of the sealing resin, that is, after the curing of the sealing resin starts but before the curing is completed.
That is, the sealing resin sheet 13 ′ is softened / melted and starts to be hardened by the heat and pressure bonding in the vacuum laminating apparatus, but the laminate is taken out from the vacuum laminating apparatus 30 before the hardening of the sealing resin is completed. The removal of the laminated body is performed by releasing the reduced pressure state of the lower chamber 32, contracting the diaphragm 311 that has expanded downward to the original state, and then raising the upper chamber 31 to open the vacuum laminating apparatus 30. be able to. In addition, the conditions of the heat compression bonding using the vacuum laminating apparatus 30 can be appropriately set according to the curing characteristics of the sealing resin to be used.
For VA, about 5 to 10 minutes at 120 ° C. to 130 ° C. is sufficient.

As shown in FIG. 3, the laminate taken out of the vacuum laminating apparatus 30 before the curing of the sealing resin is completed is melted and cast from the periphery of the glass substrate 11 as shown in FIG. The amount of the sealing resin extending portion 131 that is melted and extended is very small, and the problem of peeling of the extending portion 131 of the sealing resin at the time of reheating in the subsequent heating device does not occur.

Next, according to the present invention, the laminate shown in FIG. 3 is subjected to a heat treatment in an ordinary heating device (not shown) such as an oven to complete the curing of the sealing resin. The curing conditions can be appropriately set according to the type of the sealing resin to be used.
At a temperature of 0 ° C. or higher (less than the decomposition temperature) for 10 minutes to
This can be done in 120 minutes. Needless to say, when the curing of the sealing resin is completed, a large number of laminates can be accommodated in one oven.

In the present invention, at the time of the reheating for completing the curing of the sealing resin, at least the peripheral portion of the sealing resin layer 13 is placed in an unbound state, that is, pressure is applied from the peripheral portion of the protective film 14. It is preferable that the peripheral portion of the sealing resin 13 be placed in a free state together with the corresponding peripheral portion of the protective film 14 without applying heat or temporarily fixing the peripheral portion thereof. Thereby, the sealing resin can freely shrink during curing. As long as the peripheral portion of the sealing resin 13 is kept in the unbound state, the central portion can be thermally temporarily fixed via the protective film 14. In the example shown in FIG. 4, the protective film 14 has a circular temporary fixing portion 141 in the center region. Such temporary fixation is, for example, 70 ° C.
To 200 ° C., by pressing a pin or the like against the sealing resin layer in the central region of the protective film. By temporarily fixing the protective film 14 in this manner, it is possible to prevent the protective film 14 from being displaced when the sealing resin cures and contracts.

As described above, the solar cell module 10 as shown in FIG. 1 can be manufactured.

[0038]

Next, examples of the present invention will be described. Example 1 A front conductive oxide electrode layer, a p-type silicon semiconductor layer, an amorphous silicon photoelectric conversion layer, and an n-type silicon semiconductor layer were formed on a transparent glass substrate having a thickness of 4 mm and a size of 910 mm × 455 mm by a conventional method. A backside silver electrode layer was formed, laser scribing was appropriately performed to produce a large number of solar cell unit cells, and these were connected to produce a solar cell sub-module.

The obtained solar cell sub-module is placed on a mounting plate of a normal vacuum laminating apparatus as shown in FIG. 2A with its front face down, and an organic peroxide as a sealing resin is placed on its back face. Place a sheet of EVA resin containing
A Tedlar film was placed thereon as a protective film. Since the cure shrinkage at 150 ° C. of the EVA resin sheet used here was 0.5%, the size of the EVA resin sheet was set to 915 mm × 457 mm. The size of the protective film was set to 910 mm × 455 mm, which is substantially equal to the size of the glass substrate.

Thereafter, the laminate was heat-pressed at 130 ° C. for 5 minutes and then taken out of the vacuum laminating apparatus. At that time, the melt casting of the sealing resin from the glass substrate was very slight.

Next, a pin having a diameter of 1 cm heated to 150 ° C. was pressed against the center of the protective film of the obtained laminate to temporarily fix it. Thereafter, this was placed in a normal oven and subjected to a heat treatment at a temperature of 150 ° C. for 30 minutes to complete the curing of the sealing resin. At this time, no contamination occurred in the oven due to peeling of the sealing resin or the like. In each of the solar cell modules thus manufactured, the end face of the sealing resin layer and the end face of the protective film were substantially flush with the end face of the glass substrate.

[0042]

As described above, according to the present invention, after the sealing resin is heat-pressed in the vacuum laminating device to the middle of the curing of the sealing resin, the sealing resin is cured by another heating device. In manufacturing the solar cell sub-module by reheating for the end, since the sealing resin sheet is set to a size larger than the size of the glass substrate by the amount of shrinkage when the sealing resin is cured. In addition, contamination of the heating device by the sealing resin does not occur during reheating. Moreover, the peripheral edge surface of the sealing resin layer after the curing is substantially flush with the peripheral edge surface of the glass substrate, and the protective film to be used has a size substantially equal to the size of the glass substrate. It becomes unnecessary. Therefore, according to the present invention, a solar cell module can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a solar cell module manufactured according to the present invention.

FIG. 2 is a schematic cross-sectional view for explaining a thermocompression bonding step in a vacuum laminating apparatus when manufacturing a solar cell module according to the present invention.

FIG. 3 is a schematic sectional view showing a state of a solar cell module taken out of a vacuum laminating apparatus according to the present invention.

FIG. 4 is a plan view partially showing a protective film temporarily fixed according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 solar cell module 11 glass substrate 111 exposed peripheral portion of glass substrate 12 solar cell unit cell 120 integrated structure of solar cell unit cell 121 front transparent electrode layer 122 photoelectric conversion unit 123 back electrode layer 13 Sealing resin layer 131: Melted extension portion of sealing resin layer 13 ': Sealing resin sheet 14: Protective film 141: Temporary fixing portion 20: Solar cell sub-module 30 ... Vacuum laminating device 31: Upper chamber 311 ... Diaphragm 32 … Lower chamber 321… Mounting plate 323… Heater

Claims (7)

[Claims] 1. A sheet of a sealing resin and a protective film, which can be hardened through softening / melting by heating, on a back surface of a solar cell sub-module having a plurality of unit cells integrated on a back surface of a translucent glass substrate. And sealing the sealing resin sheet and the protective film and the solar cell sub-module in a vacuum heating / compression bonding apparatus while heating the solar cell sub-module under vacuum. After removing from the vacuum heating and pressing device, including the step of completing the curing of the sealing resin under heating in another heating device, the sealing resin sheet placed on the back surface of the solar cell sub-module Having a size larger than the size of the glass substrate by the amount of shrinkage during curing of the sealing resin, and the protective film placed on the sealing resin sheet is substantially equal to the size of the glass substrate. A method for manufacturing a solar cell module having a small size. 2. The method for manufacturing a solar cell according to claim 1, wherein a peripheral portion of the sealing resin sheet is placed in an unbound state during heating by another heating device. 3. The method for manufacturing a solar cell module according to claim 1, wherein the protective film is temporarily fixed by heat at a central portion thereof during heating by another heating device. 4. The method for producing a solar cell module according to claim 1, wherein the sealing resin comprises an ethylene / vinyl acetate copolymer containing a curing agent. 5. The method for manufacturing a solar cell module according to claim 1, wherein the protective film includes an organic fluororesin film. 6. A vacuum heat compression bonding is performed at about 120 ° C. to about 13 ° C.
The method for manufacturing a solar cell module according to any one of claims 1 to 5, wherein the method is performed at a temperature of 0 ° C for about 5 minutes to about 10 minutes. 7. The method according to claim 6, wherein the curing in the heating device is performed at a temperature of 140 ° C. or more for about 10 minutes to about 120 minutes.