JPH06204529A - Solar cell - Google Patents

Abstract

PURPOSE:To provide a solar cell which has a unit cell of a large area and can be formed with high reliability and a low cost. CONSTITUTION:Conductive fine wires 102 are buried in one surface side of a thermoplastic light permeable insulating board 101, and a transparent conductive layer 103 as a first electrode, a solar cell layer 104 and a conductive layer 105 as a second electrode are sequentially formed in this order on one side surface. In this case, the board 101 is a glass board, and is desirably softened at 400 to 600 deg.C. The wire 102 is desirably a metal wire having 10 to 200mum of its diameter. Accordingly, an electric resistance of the first electrode side can be reduced, and an increase in an area of the cell can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell having a large area single cell.

[0002]

2. Description of the Related Art Conventionally, when a solar cell is formed on a glass substrate, a transparent conductive film is formed as a first electrode on the substrate, then a photoelectric conversion layer is formed, and then a second electrode is formed thereon. The metal film is formed. on the other hand,
The solar cell is required to have a large area for practical use, but if the area is enlarged as it is, the electric resistance of the transparent conductive film is too large to effectively extract electricity.

Therefore, by using a known method such as laser scribing as shown in FIG. 6, cells are subdivided and connected in series to reduce the output current from a single cell and increase the output voltage of the entire module. There is. In FIG. 6, 601 is a transparent insulating substrate, 602 is a transparent conductive film as a first electrode, 603 is a photoelectric conversion layer, and 604.
Is a conductive layer as a second electrode.

Further, in JP-A-60-50975, as shown in FIG. 7, a groove 702 is formed on a glass substrate 701 by an etching method, and a silver paste 703 is embedded in the groove 702. Has proposed a method of forming a grid. In FIG. 7, 704 is a transparent conductive film as a first electrode, 705 is a photoelectric conversion layer, and 706 is a conductive layer as a second electrode.

[0005]

In the conventional laser scribing method for increasing the area of a solar cell, a cell is divided into small sections by using a laser beam after forming a film on a glass substrate, and the cells are connected in series. Therefore, there is a problem in that the area of the series-connected portion, which is a non-power generation portion, increases due to the increase in the number of times of series connection within one module. Further, in the latter glass substrate etching method, the process cost for etching becomes high, it becomes higher than the electric resistance metal of the silver paste by an order of magnitude, and the silver paste after curing becomes porous. There are problems such as shunting even if a film is formed on the film, and the components in the silver paste are diffused during vacuum film formation to deteriorate the film quality of the photoelectric conversion layer.

Further, in the conventional laser scribing method shown in FIG. 6, when the cell width exceeds 10 millimeters, the power loss in the transparent conductive film becomes large, so that the cell width cannot be further increased.

The present invention solves the above-mentioned conventional problems,
It is possible to make a large area single cell with high reliability and at low cost.

[0008]

In order to achieve the above-mentioned object, the present invention is to embed a conductive thin wire on one surface side of a thermoplastic translucent insulating substrate and to form a transparent conductive film as a first electrode on the one surface side. The layer, the solar cell element layer, and the conductive layer as the second electrode are formed in that order.

In this case, the translucent insulating substrate is a glass substrate, and it is desirable that it is softened at a temperature of 400 ° C. or higher and 600 ° C. or lower.

The diameter of the conductive thin wire is 10
It is desirable that the metal wire has a thickness of not less than μm and not more than 200 μm.

[0011]

In FIG. 1, 101 is a thermoplastic translucent insulating substrate which is a film forming substrate of a solar cell, 102 is a conductive thin wire, and 1
Reference numeral 03 is a transparent conductive film as a first electrode, 104 is a photoelectric conversion layer, and 105 is a conductive layer as a second electrode. The leads are taken out to take out the electric current, and the back surface is finished to ensure the weather resistance.

FIG. 2 shows a view from above in FIG. A large number of conductive thin wires 202 are arranged in parallel at equal intervals. As the thermoplastic translucent insulating substrate 201, ordinary glass is used. A film of silicon oxide may be formed on the glass surface in order to suppress the diffusion of metal ions from the glass. A metal wire such as copper or aluminum can be used as the conductive thin wire.

In order to minimize the power loss in the current path and the total loss of shadow loss due to the shadow of the conductive thin wire itself, it is good to arrange the thinnest metal wires at a narrow interval, but in practice, the diameter is reduced. It is preferable to use a metal wire of about 10 to 200 μm.

The photoelectric conversion layer may be made of amorphous silicon, crystalline silicon, or compound semiconductor. Vapor deposition of aluminum or the like is suitable for the second electrode.

FIG. 3 illustrates a method of embedding the conductive thin wire 302 in the translucent insulating substrate 301. In the figure,
Reference numeral 306 is a surface plate, and 307 is a heating device. 308
Is a pressure plate for uniformly pressing the entire surface of the translucent insulating substrate 301.

As the manufacturing procedure, first, the conductive thin wire 302 was placed on the surface plate 306, and the translucent insulating substrate 301 was placed thereon and heated. Then, the translucent insulating substrate 30
When 1 is softened, pressure is applied by the pressure plate 308 to the conductive thin wire 302.
Push into the glass. Therefore, the wire can be embedded in a state where a part of the conductive thin wire 302 is exposed on the surface of the substrate, so that it is possible to make sufficient electrical contact with the transparent conductive film. Ceramic, steel and the like are suitable as the material of the surface plate 306.

[0017]

EXAMPLE 1 In this example, as the translucent insulating substrate 101 in FIG. 1, a 700 angstrom silicon oxide film was formed on a soda glass having a thickness of 3 mm and a thickness of 10 cm by a vacuum deposition method. The formed one was prepared.
As the surface plate 106, a ceramic plate of 20 cm square is used.
Copper wires having a round cross-sectional shape of 5 angstrom and a length of 13 cm were arranged in parallel at 2 mm intervals. The substrate 101 was placed thereon, and a ceramic plate having a weight of 5 kilograms was placed thereon as the pressing plate 108.

Then, at 30 ° C. in a nitrogen gas atmosphere at 500 ° C.
When kept for a minute, the copper wire was embedded in the glass substrate with a part of the cylindrical surface exposed on the surface of the glass substrate. Using this as a film-forming substrate, an ITO film having a thickness of 1 micron and an amorphous silicon photoelectric conversion layer are further formed on the film.
The layer, the i layer, and the p layer were formed twice in this order to fabricate a solar cell having a same band gap double tandem structure. As the second electrode, aluminum was formed by vacuum vapor deposition to have a thickness of 1 micron.

A solar battery cell manufactured as described above is
Ml. When measured with a standard light source of 5,100 mW / cm ² , a conversion efficiency of about 7% was obtained. The total loss of power loss and shadow loss due to the shadow of the copper wire itself was about 3.5%.

(Embodiment 2) This embodiment is applied to a monolithic integrated cell. As shown in FIG. 2, first, a plurality of metal wires 202 are formed on a glass substrate 201.
Were intermittently arranged in the longitudinal direction, and the wire 202 was embedded in the surface of the glass substrate 201 as in the first embodiment. Then, a transparent conductive film is formed on the glass substrate 201 under the same conditions as in Example 1 above, and as shown in FIG.
As shown in FIG. 7, a known laser scribing technique is used to irradiate the P ₀ portion of the transparent conductive film 503 with the first laser beam.
Shoot. In FIG. 5A, 501 is a glass substrate and 502 is a wire.

Next, as shown in FIG. 5B, the amorphous silicon photoelectric conversion layer 50 is formed on the transparent conductive film 503.
4 and irradiate the P ₁ part with the second laser beam
It was Then, as shown in FIG.
At the stage of vapor deposition of 05, the P ₂ portion was irradiated with the third laser beam.

According to this embodiment, the cell width of the unit cell can be increased to 10 cm because the conductivity of the first electrode portion is dramatically improved, and the number of laser scribing is reduced by about 90% as compared with the conventional method. did it. As a result, the ratio of the non-power generation portion on the cell surface is reduced by about 80%, and the cell width has a degree of freedom, so that a free current value or voltage value can be obtained for a certain module size. It became so.

(Embodiment 3) In this embodiment, a mesh-shaped conductor is used instead of the copper wire in Embodiments 1 and 2. In the above-described embodiment, the copper wires are simply arranged in parallel at intervals of 2 mm, but in this embodiment, after the parallel arrangement state, the same material is further arranged at intervals of 2.5 mm so as to be orthogonal to this. Copper wire was placed to form a mesh. With this configuration, the shadow loss is about 1
%, But the workability of arranging the wires on the ceramic surface plate has improved dramatically. Further, in the case of a mesh, even if one warp wire is cut, current can be carried to the adjacent wire via the other weft wire, which is convenient.

[0024]

As described above, according to the present invention, it is possible to reduce the electric resistance on the side of the first electrode on the glass substrate, and it is possible to form a solar cell having a larger area than the conventional one. As a result, the structure and manufacturing process of the solar cell are simplified, the reliability of the product is improved, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the configuration of a solar cell according to the present invention.

FIG. 2 is a top view of FIG.

FIG. 3 is a schematic side sectional view for explaining embedding of a conductive thin wire.

4A and 4B are diagrams showing a configuration of a solar cell according to Example 2, where FIG. 4A is a top view and FIG. 4B is a sectional view taken along line XX.

FIG. 5 is a diagram showing an example of respective steps (a) to (c) of cell integration.

FIG. 6 is a cross-sectional view showing a configuration example of a conventional solar cell.

FIG. 7 is a cross-sectional view showing a configuration example of another conventional solar battery cell.

[Explanation of symbols]

101, 201, 301, 401, 501 translucent insulating substrate, 102, 202, 302, 402, 502 conductive thin wire, 103, 503 transparent conductive film, 104, 504 photoelectric conversion layer, 105, 505 as second electrode Conductive layer.

Claims (3)

[Claims] 1. A conductive thin wire is embedded on one surface side of a thermoplastic translucent insulating substrate, and a transparent conductive layer as a first electrode, a solar cell element layer, and a conductive layer as a second electrode are provided on the one surface side. A solar cell characterized by being formed in that order. 2. The solar cell according to claim 1, wherein the translucent insulating substrate is a glass substrate and is softened at a temperature of 400 ° C. or higher and 600 ° C. or lower. 3. The conductive thin wire has a diameter of 10 μm.
The solar cell according to claim 1 or 2, wherein the solar cell is a metal wire having a size of 200 µm or more.