JP2013149770A - Solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery which is capable of suppressing an increase in electrical resistance between a solar cell and metal foil wiring due to an increase in the number of temperature cycles.SOLUTION: The solar battery includes: a solar cell 3; a metal foil 5 which has an uneven surface facing the solar cell 3, wherein a plurality of projections of the uneven surface are in contact with the solar cell 3; and an adhesive 4 bonding recesses of the uneven surface to the solar cell 3.

Description

  The present invention relates to a solar cell provided with a metal wiring structure.

  Japanese Patent Application Laid-Open No. H10-228667 includes a flexible solar cell that includes a thin-film semiconductor photoelectric conversion layer formed on a flexible substrate and sandwiched between electrode layers, and is sealed between double-sided protective materials via a binder resin. In the method for manufacturing a thin-film solar battery module, the electrode of the solar battery cell and the lead wire are connected by a conductive adhesive, and the conductive adhesive is cured in the same heating step as that of sealing with a binder resin. A method for manufacturing a flexible thin film solar cell module is disclosed.

  In Patent Document 2, an output electrode having a different polarity of a solar tile in which a thin-film solar cell is formed on a flexible substrate and two main wirings are connected via secondary wirings, respectively. A flexible thin-film solar cell in which a secondary wiring is an aluminum tape with a conductive adhesive is disclosed in a flexible solar cell module that is sandwiched and sealed by a protective film via an adhesive resin film.

  A cross-sectional view of the solar cell described in Patent Documents 1 and 2 is shown in FIG. The solar cell 3 is provided with the sealing material 2 and the surface protection film 1 on the light receiving surface side, and the conductive adhesive 8, lead wire or aluminum tape 5a (corresponding to the metal foil 5 of the present invention) on the non-light receiving surface side. The binder resin 6a and the back surface protective film 7 are provided.

JP-A-8-213643 JP-A-10-335686

  Until now, the solar cell has been subjected to a temperature cycle as a durability test simulating the installation environment of the solar cell. The conventional solar cell wiring structure as described above has a problem in that the electrical resistance between the solar cells and the wiring tends to increase as the number of temperature cycles increases.

  An object of this invention is to provide the wiring structure of the solar cell which can suppress the increase in the electrical resistance between the photovoltaic cell and metal foil wiring by the increase in the number of temperature cycles.

  In order to solve the above-mentioned problem, a first aspect of the present invention is to provide a solar cell and an uneven surface on a surface facing the solar cell, and the convex portion of the uneven surface is in contact with the solar cell. A metal foil, a concave portion of the concave and convex surface, and an adhesive for adhering the solar battery cell.

  According to such a configuration, since the metal foil and the solar battery cell are in direct contact with each other, the electrical resistance can be kept low, and an adhesive having a high contact adhesive strength can be used as a material for the adhesive regardless of the presence or absence of conductivity. Can be arbitrarily selected.

The metal foil is preferably made of copper or aluminum, has a thickness of 10 to 100 μm, and has a surface plated with tin or gold.
According to such a structure, since the part which contacts a photovoltaic cell is plated using copper and aluminum which are metals with good electroconductivity, electrical connectivity can be improved.

  The adhesive may be an acrylic, rubber, silicone, or urethane adhesive. It is more desirable to use an acrylic or rubber adhesive having high adhesive strength.

According to such a configuration, it is possible to suppress peeling between the solar battery cell and the metal foil that is likely to occur due to a temperature cycle.
The adhesive may be a conductive adhesive. This conductive adhesive is manufactured by mixing a conductive member such as silver powder or carbon powder into the acrylic, rubber, silicone, or urethane adhesive.

According to such a configuration, the conductive surface can be widened.
Moreover, it is desirable that the convex portions or the concave portions are arranged in a staggered pattern, a mesh pattern, or a striped pattern.

According to such a configuration, the concave portions that are the bonded portions can be distributed almost uniformly, so that the bonding strength can be improved.
And it is desirable that the non-light-receiving surface of the solar battery cell is in contact with the convex portion.

  According to such a configuration, since the metal foil is provided on the non-light-receiving surface instead of the light-receiving surface, electrical wiring can be performed on the non-light-receiving surface without covering the light-receiving surface of the solar battery cell. Therefore, the amount of received light can be increased and the amount of power generation can be increased compared to the case where a metal foil is disposed on the light receiving surface side.

  ADVANTAGE OF THE INVENTION According to this invention, the wiring structure of the solar cell which can suppress the increase in the electrical resistance between the photovoltaic cell and metal foil wiring by the increase in the number of temperature cycles can be provided.

Sectional drawing which concerns on 1st aspect of this invention (Example with an uneven | corrugated surface cross section corrugated) Example of uneven surface cross section rectangular Example where the concave or convex portions have a staggered pattern Example where the concave or convex portion is a mesh pattern Example in which concave or convex portions are striped Temperature cycle test results Sectional view of a conventional solar cell

  Hereinafter, embodiments of the solar cell according to the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment, In the range which does not change the summary, it can implement suitably.

  FIG. 1 is a cross-sectional view according to the first aspect of the present invention (an example in which the concave-convex surface cross-section is corrugated). The solar battery cell 3 is provided with the sealing material 2 and the surface protective film 1 on the light receiving surface side, and with the adhesive 4, the metal foil 5, and the back surface protective film 7 on the non-light receiving surface side. The surface of the metal foil 5 facing the solar battery cell 3 is an uneven surface 9, and the convex portion of the uneven surface 9 is in contact with the solar battery cell 3.

  The adhesive 4 is filled in the concave portion of the uneven surface 9 and adheres the concave portion and the solar battery cell 3. The adhesive may be an acrylic, rubber, silicone, or urethane adhesive. It is more desirable to use an acrylic or rubber adhesive having high adhesive strength. The adhesive may be a conductive adhesive. This conductive adhesive is manufactured by mixing a conductive member such as silver powder or carbon powder into the acrylic, rubber, silicone, or urethane adhesive.

In addition, FIG. 1 is the figure which looked at the AA cross section of FIG.
As a different mode from FIG. 1, a structure as shown in FIG. 2 may be used. FIG. 2 shows an embodiment in which the concave and convex surface has a rectangular cross section. FIG. 2 has the same structure as FIG. 1 except that the concave and convex surface of the concave and convex surface of FIG. 1 is rectangular.

  In the structure in which the concave and convex surface of the concavo-convex surface in FIG. 1 is corrugated or in the structure in which the concave and convex surface of the concavo-convex surface in FIG. It can be made into a simple shape.

FIG. 3A is a view of the concavo-convex surface of FIG. 1 as viewed from above, and is an embodiment in which the concave portions have a staggered pattern. The convex portion is the metal foil 5, and the concave portion is filled with the adhesive 4.
As a modification of FIG. 3A, a structure as shown in FIG. FIG. 3B shows an example in which the convex portions have a staggered pattern. The convex portion is the metal foil 5, and the concave portion is filled with the adhesive 4.

As an aspect different from the above, FIG. 4A shows an embodiment in which the concave portion has a mesh pattern. The convex portion is the metal foil 5, and the concave portion is filled with the adhesive 4.
As a modification of FIG. 4A, a structure as shown in FIG. FIG. 4B shows an example in which the convex portion has a mesh pattern. The convex portion is the metal foil 5, and the concave portion is filled with the adhesive 4.

As an aspect different from the above, FIG. 5A shows an embodiment in which the recesses are striped. The convex portion is the metal foil 5, and the concave portion is filled with the adhesive 4.
As a modification of FIG. 5A, a structure as shown in FIG. FIG. 5B shows an example in which the convex portion has a striped pattern. The convex portion is the metal foil 5, and the concave portion is filled with the adhesive 4.

  FIG. 6 is a diagram showing the results of the temperature cycle test. FIG. 6 shows the result of the conventional structure of FIG. 7 (triangle mark), the result of the structure of the embodiment of the present invention in FIG. In (b), the cross section of the concavo-convex surface showed the result of the corrugated structure (circle).

  In the solar cell having a rectangular structure in FIG. 4B, the section of the concavo-convex surface is 0.7 mm in length and width for each portion of the metal foil exposed to the solar battery cell, and the portion of the metal foil exposed. The experiment was carried out so that the distance between them was 3.0 mm, the depth of the metal foil was 0.08 mm, and the ratio of the exposed area of the metal foil to the area of the adhesive was 5%.

  In the solar cell having a corrugated cross section in FIG. 3B, the dimension of each part of the metal foil exposed to the solar battery cell is between the radius of 0.27 mm and the part of the metal foil exposed. The experiment was conducted such that the distance was 3.0 mm, the depth of the unevenness of the metal foil was 0.13 mm, and the ratio of the exposed area of the metal foil to the area of the adhesive was 10%.

  In the conventional example, the electrical resistance increased remarkably as the temperature cycle increased, but in the example of the present application, the increase in electrical resistance could be suppressed. In addition, although presentation of the result by a graph is abbreviate | omitted, also in each Example of FIG. 3 (a), FIG. 4 (a), FIG. 5 (a), and FIG. As a result, the increase in electric resistance was suppressed in the embodiment of the present invention.

  When the ratio of the exposed area of the metal foil to the area of the adhesive was changed to 5 to 25% and examined, the area of the adhesive is preferably larger than the exposed area of the metal foil, and the optimal range of this ratio is 5 to 5%. 15%.

DESCRIPTION OF SYMBOLS 1 Surface protective film 2, 6 Sealing material 3 Solar cell 4 Adhesive 5 Metal foil 5a Aluminum tape 6a Binder resin 7 Back surface protective film 9 Uneven surface

Claims (8)

Solar cells,
A metal foil having a concavo-convex surface on the surface facing the solar battery cell, wherein the convex part of the concavo-convex surface is in contact with the solar battery cell,
An adhesive that bonds the concave and convex portions of the uneven surface and the solar battery cells;
A solar cell comprising: 2. The solar cell according to claim 1, wherein the metal foil is made of copper or aluminum, has a thickness of 10 μm or more and 100 μm or less, and has a surface plated with tin or gold. . The solar cell according to claim 1, wherein the adhesive is an acrylic, rubber, silicone, or urethane adhesive. The solar cell according to claim 1, wherein the adhesive is a conductive adhesive. The solar cell according to claim 1, wherein the convex portions or the concave portions are arranged in a staggered pattern. The solar cell according to claim 1, wherein the convex portion or the concave portion is arranged in a mesh pattern. The solar cell according to claim 1, wherein the convex portion or the concave portion is arranged in a striped pattern. The solar cell according to claim 1, wherein the non-light-receiving surface of the solar cell is in contact with the convex portion.

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