JPH1154780A - Thin-film solar cell module - Google Patents

Abstract

(57) [Summary] [Problem] To provide a low-cost, low-voltage, high-voltage output solar cell module that has excellent electrical insulation and is optimal for all uses including building material integration. SOLUTION: A box-shaped back plate having a side wall at a peripheral portion, a translucent substrate housed inside the side wall so as to be parallel to the back plate at a predetermined interval, a back plate and a translucent substrate And a thin film solar cell element formed by exposing the air chamber on the light-transmitting substrate, and being filled around the back plate and the peripheral edge of the light-transmitting substrate. And a lead wire connected to a thin-film solar cell element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin, high-voltage thin-film solar cell module suitable for being installed on a roof or integrated with various building materials.

[0002]

2. Description of the Related Art Conventionally, in a thin film solar cell module using a hydrogenated amorphous silicon element, the element is sealed with a flammable transparent resin such as an EVA resin (ethylene-vinyl acetate copolymer). Since solar cell modules using such hydrogenated amorphous silicon elements use a large amount of flammable EVA transparent resin having a low melting point, similar to general crystalline solar cell modules, they are stipulated in the Building Standards Law of Japan. It is difficult to comply with the fireproof regulations for building materials. Further, at present, the solar cell module having the structure in which the solar cell element is embedded in the EVA resin is very difficult to separate each member, and thus cannot be disassembled and disposed of at the time of disposal.

On the other hand, in the case of a thin-film solar cell module using CdS / CdTe elements, as shown in FIG. 6, an air chamber 66 having an average thickness of 10 mm or more is provided between the element 61 and the back plate 63. (National Technical Report VOL.37 No.1, Feb.1991) This is because, in past experiments, when a CdS / CdTe element sealed in a transparent container was used outdoors, the oxygen concentration in the container gradually decreased, and when used in a vacuum container, CdS / CdT
Based on the result that the characteristics of the e-element are degraded, the design concept is to provide an air chamber to secure a certain amount of oxygen.

[0004] However, the thin-film solar cell module has the following problems. As a sealing material, the air chamber 66 is sealed, and the translucent substrate 62 and the back plate 6 are sealed.
3 must be firmly joined. However, a sealing material having both the water vapor transmission rate and the adhesive strength required to seal and maintain the air chamber 66 having a thickness of 10 mm or more has not been reported so far. Therefore, two types of sealing materials are used: a main sealing material 64 for sealing the air chamber 66 and an adhesive sealing material 65 having a large bonding strength. As the main sealing material 64, for example, butyl rubber is used.
For example, a curable silicone rubber is used.
Further, in assembling, after the translucent substrate 62 and the back plate 63 are joined in advance by the main sealing material 64, it is necessary to further fill an adhesive sealing material 65 therebetween. The operation of filling the adhesive sealing material 65 is inefficient and requires a long time.

Further, when the translucent substrate 62 and the back plate 63 are joined only with the sealing material, the adhesive sealing material 6 is deformed due to a pressure change of the sealed air chamber 66 or deformation due to external stress.
5 is not repaired when it is peeled off from the light-transmitting substrate 62 or the back plate 63, a structure is adopted in which the light-transmitting substrate 62 and the back plate 63 are fixed with a large number of screws 68 using a fixing frame 67 for reinforcement. I have. Such a structure also causes low productivity and high cost. As described above, the complicated processing and structure are required, and the productivity of the solar cell module is low.
Its manufacturing cost is high. Further, in the solar cell module having such a structure, when a sufficient volume of the air chamber 66 is secured, the thickness of the central portion excluding the fixed frame 67 is about 16 mm.
As described above, the thickness including the fixed frame 67 is about 20 mm or more. Therefore, when integrated with building materials, it is difficult to handle. Also, it is not preferable in terms of design.

Further, such a solar cell module is
In recent years, it has been difficult to separate and disassemble members at the time of disposal, which has been increasingly demanded. For example, it is difficult to separate a cross-linkable silicone resin or the like used for the adhesive sealing material 65. Also, non-adhesive and high-hardness resin containing a large amount of thermoplastic resin used for the main sealing material 64 is hard to peel off and is relatively difficult to separate.

From the viewpoint of the performance of the battery, the electrical connection between a pair of lead wires 69 for outputting a current from the positive and negative electrodes of the solar cell element 61 housed in the air chamber 66 and the metal back plate 63. In order to ensure insulation and airtightness of the air chamber 66, for example, an O-ring is attached, and an insulating spacer 70 is attached. However, according to this method,
The withstand voltage of the spacer 70 is as low as 2.5 kV. further,
In order to blacken the light receiving surface of the element so as to be inconspicuous in appearance, and to obtain a hardness that withstands a change in the internal pressure of the air chamber 66, about 25% or more of carbon is added to the main sealing material 64 as an inorganic filler. You. Such a sealing material to which a large amount of carbon is added does not pose a problem for small independent power supply applications, but has a low electrical insulation property and a low withstand voltage when used on a roof or used integrally with a building material.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above problems and realizes a thin-film solar cell module excellent in electric insulation and thin with a simple structure.
It is an object of the present invention to provide an inexpensive solar cell module suitable for all uses including integration with building materials.

[0009]

Means for Solving the Problems In a CdS / CdTe solar cell module, conventionally, as described above, the air chamber is:
It was thought to function as an oxygen supply space. However, as a result of verification, it was found that the initial decrease in the fill factor was caused by the heat-dried or cured protective resin film, and thereafter, the stability was stabilized. Therefore, the air chamber does not need to be large. However, in order to avoid the influence of the atmosphere on the ohmic contact between the carbon electrode and the semiconductor, which is a mechanical contact, it is necessary to secure an air chamber with a minimum volume. Therefore, the capacity of the air chamber can be reduced, and the thickness of the solar cell module can be reduced. Therefore, the thickness of the air chamber is 1 to
5 mm, and the air chamber is used as a non-combustible insulating layer for ensuring a withstand voltage. Here, it is not necessary to use two types of sealing materials as in the related art, and the productivity is greatly improved by using an adhesive material for the sealing material and greatly reducing the thickness of the air chamber. be able to.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A thin-film solar cell module according to the present invention is provided so that a box-shaped back plate having a side wall at a peripheral edge and a flat plate portion of the back plate inside the side wall are parallel to each other at a predetermined interval. The housed light-transmitting substrate, an air chamber formed by a space between the back plate and the light-transmitting substrate, and a thin-film solar cell element formed on the light-transmitting substrate and exposed to the air chamber, It comprises an insulating and adhesive sealing material which is filled around the periphery of the back plate and the translucent substrate to seal the air chamber, and a lead wire connected to the thin-film solar cell element. Thus, the module can be sealed with a simple structure. Therefore, member costs and assembly costs can be significantly reduced.
In addition, the module can be significantly reduced in thickness. Furthermore, since it is not necessary to use two types of sealing materials, it is possible to greatly improve flame retardancy and non-combustibility. Therefore, a thin, thin-film solar cell module that is most suitable for roofing and building material integration that requires durability can be obtained. Further, the separation of the member after recovery as industrial waste is facilitated.

In a preferred embodiment of the thin-film solar cell module of the present invention, the back plate is obtained by bending a single metal plate to form a side wall. Another thin-film solar cell module of the present invention includes a back plate, a light-transmitting substrate disposed close to and parallel to the back plate at a predetermined distance, and a back plate and a light-transmitting substrate. An air chamber formed by the space portion of the above, a thin-film solar cell element formed on the light-transmitting substrate and exposed to the air chamber, and an air chamber filled around the periphery of the back plate and the light-transmitting substrate. And a lead wire connected to the thin-film solar cell element and a spacer including an insulating adhesive material partially disposed in the space. Thereby, even in a module having a large area, the approach and contact between the back plate and the solar cell element can be prevented.

Still another thin-film solar cell module according to the present invention is housed in a box-shaped back plate having a side wall at a peripheral edge thereof and inside the side wall so as to be parallel to a flat plate portion of the back plate at a predetermined interval. A light-transmitting substrate, an air chamber defined by a space between the back plate and the light-transmitting substrate, a thin-film solar cell element formed on the light-transmitting substrate and exposed to the air chamber, An insulating sealing material that is filled around the periphery of the plate and the translucent substrate to seal the air chamber, and a lead wire connected to the thin-film solar cell element, and the back plate has a cutout in the side wall. And the lead wire penetrates the sealing material, and is further led out through a cutout portion of the side wall of the back plate. As a result, the output terminal can be sealed at the same time, so that the productivity can be further improved. In a preferred embodiment of the thin-film solar cell module of the present invention, a connection terminal for connecting to an external device, a terminal protection portion for covering and protecting the connection terminal, and a collar for tightly covering the notch portion from the outside. A cover having a portion.

In another preferred embodiment of the thin-film solar cell module according to the present invention, an insulating substrate joined to a back plate, a pair of conductive films formed on the insulating substrate, a diode connecting the conductive films, and a conductive film It has a connection terminal for connecting one to an external device, and the other of the conductive films is connected to a lead wire. In still another preferred embodiment of the thin-film solar cell module according to the present invention, the sealing material contains butyl-based rubber as a main component, contains 15% by weight or less of carbon, and has a volume resistivity of 10 ¹⁰ Ωm or more. Thereby, insulation resistance and dielectric strength can be improved.
Urethane, silicone and acrylic adhesives
Since both have high water vapor transmission rates, it is difficult to use them as sealing materials for sealing the air chamber.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIGS. 1 and 2 show a thin-film solar cell module of this embodiment. C on the surface in advance
A translucent substrate 2 such as a glass substrate on which a thin-film solar cell element 1 such as dS / CdTe is formed and a box-shaped back plate 11 having a side wall 11b around it are arranged close to each other. Here, back plate 1
1 is formed by bending a stainless steel plate having a thickness of 0.2 to 1 mm to form side walls 11b around a flat plate portion 11a, and has cuts 20 at four corners. Also, the lead wire 15 connected to the solar cell element 1 is provided on the side wall 11 b with the back plate 1.
A cutout portion 19 for leading out to the outside is formed. After leading out the lead wire 15 composed of a pair of flat core wires connected to the solar cell element 1 to the outside of the back plate 11 from the notch portion 19, either one of the translucent substrate 2 or the back plate 11 is guided. An insulating adhesive material mainly composed of butyl rubber is applied around the outer peripheral portion as the sealing material 12. Next, the translucent substrate 2 and the back plate 11 are overlaid and bonded to be integrated. At this time, the lead 15 is also fixed by the sealing material 12. An air chamber 13 is formed between the translucent substrate 2 and the back plate 11. The thickness of the air chamber 13 is to ensure insulation between the solar cell element 1 and the back plate 11,
In consideration of the stress deformation of the back plate 11 at a low temperature, 1 mm or more is preferable. In consideration of the influence of the atmosphere in the air chamber 13 and the reduction in the thickness of the module, the thickness is preferably 5 mm or less.

On the outer surface of the back plate 11, an insulating relay terminal plate 14 having a pair of conductive foils 14a on the surface is fixed in advance. A lead wire 15 is soldered to one side of the conductor foil 14a, and a cabtire cable for connection to the outside is connected to the other side. As a result, no external force is applied to the lead wire 15. In addition, a diode 21 having a reverse withstand voltage of 100 V to 150 V or more is connected between the conductor foils 14 a to prevent back flow. In order to reduce costs,
It is also possible to use one notch and one relay terminal plate, and connect the positive and negative lead wires to the same relay terminal plate.

The back plate 11 is provided with a ventilation hole 17 for preventing the internal pressure of the air chamber 13 from increasing when the sealing material 12 is filled. This ventilation hole 17 is formed with a sealing material 18.
The air chamber 13 is sealed by closing with air. Back plate 11
However, when a solderable material such as a stainless steel plate or a nickel-plated steel plate is used, the air chamber 13 can be sealed by soldering. When a vinyl chloride steel plate is used, a metal plate or the like is bonded and sealed. By fixing a small amount of desiccant on the back plate 11 in the air chamber 13 as necessary, dew condensation in the air chamber 13 can be prevented. When the translucent substrate 2 is made of glass, after the solar cell element 1 is formed, matting is performed on the surface of the translucent substrate 2 opposite to the side provided with the solar cell element 1, that is, the light receiving surface. By coating with the applied fluorine-based resin film having a thickness of 20 to 100 μm, it is possible to prevent specular reflection and scattering when the translucent substrate 1 is damaged.

The terminal cap 23 is made of a resin such as polycarbonate or stainless steel, and protects the relay terminal plate 14 and its connection. The plate-like brim portion 23a is in close contact with the notch portion 19 of the back plate 11 to prevent the sealing material 12 from protruding. The groove 23b secures the cabtire cable for external connection, and receives the relay terminal plate 1 from external force applied to the cable.
4 and its connections are protected. When a metal such as stainless steel is used for the back plate 11 and the terminal cap 23, high fire resistance and nonflammability can be obtained. Further, since high mechanical strength is obtained, impact resistance is also improved.

The light-transmitting substrate 2 has a width of 435 mm and a length of 175 mm, or a width of 870 mm and a length of 175 m.
The glass substrate having a thickness of 2.7 mm and a thickness of 2.7 mm, and the back plate 11 using a stainless steel plate having a thickness of 0.5 mm were used.
3 was 2.8 mm in thickness to produce a solar cell module. The thickness at the center of the obtained solar cell module is 6
mm. This value is 40% or less of the thickness of the solar cell module having the same output as the conventional one. As described above, according to the present embodiment, the thickness of the solar cell module can be significantly reduced. Further, according to the present embodiment, one type of sealing material may be used. Further, in this embodiment, the back plate 11 having the cuts 20 at the four corners obtained by bending a stainless steel plate.
However, the airtightness of the air chamber 13 is maintained by the adhesive sealing material 12, and a solar cell having good characteristics can be obtained.
Therefore, material costs and manufacturing costs can be significantly reduced.

In the above-described embodiment, a frameless thin-film solar cell module that can be made particularly thin has been described. However, a frame may be provided for mounting and fixing or for external design. For example, in order to increase the reliability in use in a high-temperature area such as a desert, a structure in which the translucent substrate 2 cannot be removed using a key-shaped frame is used. However, also in the solar cell module of the above embodiment, in normal installation, the light receiving surface is directed upward to receive the sunlight, and the viscoelastic frictional force of the sealing material 12 and the closed air pressure of the air chamber 13 cause light transmission. There was no example in which the conductive substrate 2 dropped from the back plate 11.

The thin-film solar cell module of this embodiment is
The translucent substrate 2 provided with the solar cell element 1 and the back plate 11 are fixed only at the outer periphery by a sealing material 12, and the sealing material 12 is adhesive. Therefore, after the disposal and collection, the transparent substrate 2
And the box-shaped back plate 11 can be easily separated. It does not peel off instantaneously due to the viscoelastic properties of the sealing material 12, but is separated without breaking the light-transmitting substrate 2 or the back plate 11 by applying a relatively small external force for a certain period of time at room temperature or heating. Can be. Further, the sealing material 12 can be easily separated by a method in which the sealing material 12 is dissolved by being immersed in a ketone, a thinner-based or alcohol-based organic solvent, or the like.

Therefore, the solar cell module according to the present embodiment can solve the problem of waste collection, which will become a major social problem as it spreads. In particular, Cd, T
It is useful for compound thin film solar cells containing heavy metals such as e, In, Se, Ga, and Cu and rare metals.

Next, the improvement of the withstand voltage of the solar cell module as described above will be described. In the thin-film solar cell module of this example, the withstand voltage of the module was measured by changing the type and thickness of the relay terminal plate 14 adhered to the metal back plate 11. The result is shown in FIG. Generally, when electric lines of force are applied perpendicularly to the insulating substrate, the accumulated charges cause creeping discharge. Therefore, the influence of the length from the end of the conductor foil 14a to the end of the relay terminal plate 14 (represented by an edge (mm) in the drawing) and the material of the relay terminal plate 14 can be neglected. This depends on the thickness of the relay terminal plate 14. As shown in FIG. 3, by setting the thickness of the relay terminal plate 14 to 1 mm or more, a withstand voltage of 3 kV or more could be obtained. Further, when the relay terminal plate 14 was molded with a silicone resin, a sufficient withstand voltage of 5 kV or more was obtained even when the metal terminal cap 23 was used.

Next, the types of the sealing material will be described. A sealing material is prepared by uniformly dispersing carbon (furnace black) at a weight ratio of 0.01% to about 25% by weight in three types of butyl rubber-based adhesives A, B and C having different average molecular weights. did. However, each of A, B and C is composed of a mixture of a butyl rubber-based adhesive having a molecular weight of 50,000 or more and a butyl rubber-based adhesive having a molecular weight of 5,000 or less. Further, these sealing materials contain 1 to 40% by weight of an inorganic filler having a different composition such as a silicate or a carbonate for adjusting the viscosity and the tackiness. The volume resistivity at room temperature with respect to the carbon filling rate of these sealing materials was measured.
FIG. 4 shows the results. A sealing material using any of the adhesives A, B and C exhibits a high volume resistivity of 10 ¹⁰ Ωm or more when the carbon filling rate is 15% by weight or less.
Further, it can be seen that the difference in the composition of the sealing material does not significantly affect the volume resistivity. When the carbon filling rate exceeds 15%, the reason why the volume resistivity decreases sharply is considered that the carbon particles dispersed in the butyl rubber are bonded to each other to form a conductive path.

Even when the carbon filling rate is 0.01% by weight, a black coloring effect can be obtained. The volume resistivity in this case is about 1 × 10 ¹³ Ωm, which is almost the same as the value of the sealing material having a carbon filling rate of 0.03% by weight measured by the same measuring method.

Using these sealing materials, the same solar cell modules as described above were produced. The insulation resistance between the back plate and the terminal of the thin-film solar cell element at a voltage of 1000 V of the obtained solar cell module was measured. The solar cell module using the sealing material in which the adhesive material A was filled with 25% by weight of carbon had a low insulation resistance of 10 ³ to 10 ⁵ Ω and was unstable. However, even when any of the adhesives A, B and C was used, an excellent insulation resistance of 1 × 10 ⁹ Ω or more was obtained by setting the carbon loading to 15% by weight or less.

Embodiment 2 According to Embodiment 1, for example, the width is 880 mm and the length is 360 mm, or the width is 980 m.
In the case of a thin-film solar cell module having a large area such as m and a length of 660 mm, it is difficult to stably maintain the air chamber. That is, since the air chamber is thin, there is a concern that the back plate is deformed due to mechanical stress or thermal stress and comes into contact with the solar cell element. Therefore, in such a large-sized solar cell module, the spacer 55 is partially disposed on the inner surface of the back plate 41 facing the air chamber 43 as shown in FIG. Thereby, contact between the back plate 41 and the solar cell element 31 due to mechanical deformation or deformation due to thermal stress can be easily prevented. As the spacer 55, the sealing material 42
The same pressure-sensitive adhesive containing butyl rubber as a main component can be used. Further, as the spacer 55, the sealing material 42 is used.
Since various types of materials such as urethane-based materials can be used because they do not require excellent water vapor transmission rate and adhesive force as in the above. It is effective to dispose the spacer 55 at a position corresponding to the center of the air chamber 43 where the back plate 41 and the solar cell element 31 are most likely to approach each other. In addition, a plurality of minute spacers may be scattered, or the spacers may be arranged in a row.

For example, by using the same material as the sealing material 42 for the spacer, it is possible to apply the same material to the back plate or the transparent substrate in the same manner as the sealing material. Therefore, if an automatic coating device is used, it is not necessary to add a new process.
In addition, by using an adhesive sealing material, there is no mechanical damage such as separation of the solar cell element due to deformation of the back plate. Furthermore, since the impact applied to the light-transmitting substrate can be absorbed by the sealing material, the impact resistance of the solar cell module can be improved. Even when a metal plate such as stainless steel is used for the back plate, sufficient insulation and high withstand voltage as a solar cell module can be secured by using a spacer having the same insulation as the sealing material for the spacer. . Further, the easiness of separating and disassembling the members in the waste collection is not impaired.

In each of the above embodiments, furnace black, which is often used for rubber, is used as carbon to be added to the sealing material. However, thermal black or channel black may be used. In addition to CdS / CdTe solar cell elements, the present invention can be easily applied to modules using other thin film solar cell elements such as hydrogenated amorphous silicon elements, thin film polycrystalline silicon elements, compound copper indium selenium elements, and the like. be able to.

[0030]

According to the present invention, it is possible to provide a low-cost, high-performance solar cell module which is thin and is suitable for roof installation or integrated with building materials.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a thin-film solar cell module according to one embodiment of the present invention.

FIG. 2 is an exploded perspective view of a part of the thin-film solar cell module.

FIG. 3 is a characteristic diagram showing a relationship between a thickness of a relay terminal plate and a withstand voltage.

FIG. 4 is a characteristic diagram showing a relationship between a carbon filling rate of a sealing material and a volume resistivity.

FIG. 5 is a longitudinal sectional view of a thin-film solar cell module according to another embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a thin-film solar cell module of a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thin-film solar cell element 2 Translucent substrate 11 Back plate 11a Flat plate portion 11b Side wall 12 Sealing material 13 Air chamber 14 Relay terminal plate 14a Conductive foil 15 Lead wire 17 Vent hole 18 Sealing material 19 Cut groove 20 Cut 21 Diode 23 Terminal Cap 23a Collar 23b Groove 31 Thin-film solar cell element 41 Back plate 42 Sealing material 43 Air chamber 55 Spacer 61 Solar cell element 62 Translucent substrate 63 Back plate 64 Main sealing material 65 Adhesive sealing material 66 Air chamber 67 Fixed frame 68 Screw 69 Spacer 70 Lead wire

Claims (7)

[Claims] A box-shaped back plate having a side wall at a peripheral portion; a light-transmitting substrate housed inside the side wall so as to be parallel to a flat plate portion of the back plate at a predetermined interval; An air chamber formed by a space between the back plate and the light-transmitting substrate; a thin-film solar cell element formed on the light-transmitting substrate so as to be exposed to the air chamber; An insulating sealing material that is filled around the periphery of the optical substrate and seals the air chamber, and a lead wire connected to the thin-film solar cell element is provided, and the sealing material has adhesiveness. Having a thin-film solar cell module. 2. The thin-film solar cell module according to claim 1, wherein the back plate is obtained by bending a single metal plate. 3. A back plate, a light-transmitting substrate disposed close to and parallel to the back plate at a predetermined distance, and a space between the back plate and the light-transmitting substrate. The configured air chamber, a thin-film solar cell element formed on the light-transmitting substrate and exposed to the air chamber, and the peripheral plate of the back plate and the light-transmitting substrate is filled and filled. A thin-film solar cell comprising: an insulating sealing material that seals an air chamber; a lead wire connected to the thin-film solar cell element; and a spacer including an insulating adhesive material partially disposed in the space. Battery module. 4. A box-shaped back plate having a side wall at a peripheral portion, a translucent substrate housed inside the side wall so as to be parallel to a flat plate portion of the back plate at a predetermined interval, and An air chamber formed by a space between the back plate and the light-transmitting substrate; a thin-film solar cell element formed on the light-transmitting substrate so as to be exposed to the air chamber; An insulating sealing material that is filled around the periphery of the optical substrate to seal the air chamber, and a lead wire connected to the thin-film solar cell element, wherein the back plate is cut into the side wall. A thin-film solar cell module including a notch, wherein the lead wire penetrates the sealing material, and is further led out through a notch in a side wall of the back plate. 5. A connection terminal for connecting to an external device,
The thin-film solar cell module according to claim 4, further comprising a cover having a terminal protection portion for covering and protecting the connection terminal and a flange portion for covering the notch portion from outside. 6. An insulating substrate bonded to the back plate, a pair of conductive films formed on the insulating substrate, a diode connecting between the conductive films, and one of the conductive films for connecting one of the conductive films to an external device. The thin-film solar cell module according to claim 1, further comprising a connection terminal, wherein the other of the conductive films is connected to the lead wire. 7. The sealing material according to claim 1, wherein the sealing material is mainly composed of an adhesive made of butyl rubber, contains 15% by weight or less of carbon, and has a volume resistivity of 10 ¹⁰ Ωm or more. Thin film solar cell module.