JP2004342768A - Thin film solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film solar cell module with high versatility using a conductive substrate. <P>SOLUTION: A plurality of unit cells 10 connected in series are arranged. The unit cell 10 includes: a conductive substrate 11; and a first electrode layer 12, a semiconductor layer 13, and a second electrode layer 14 which are arranged on the conductive substrate 11 in order from the substrate 11 side. At least a part of ends 11a of the substrate 11 is bent to a second electrode 14 side. Two adjacent unit cells 10 are connected in series by bringing the ends 11a of one unit cell 10 into contact with the second electrode layer 14 of the other unit cell 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thin-film solar cell module.
[0002]
[Prior art]
Conventionally, CuInSe ₂ (CIS), which is a compound semiconductor thin film (chalcopyrite structure semiconductor thin film) composed of a Group Ib element, a Group IIIb element, and a Group VIb element, or Cu (In, Ga) Se in which Ga is dissolved in this ₂ (CIGS) or a structure and a manufacturing method of a thin film solar cell module using CuInS ₂ for a light absorbing layer have been reported (for example, see Non-Patent Document 1). In such a CIS-based thin film solar cell, an integrated structure in which a plurality of unit cells are connected in series on a substrate is generally used.
[0003]
An example of a conventional method for manufacturing a CIS-based thin-film solar cell module will be described with reference to FIG. First, as shown in FIG. 5A, after a first electrode layer 2 is formed on an insulating substrate 1 such as glass by a sputtering method, the first electrode layer 2 is irradiated with a continuous wave laser beam. The layer 2 is removed in a stripe shape to form a strip-shaped first electrode layer 2. Thereafter, as shown in FIG. 5B, a semiconductor film 3 composed of a laminated film of a p-type Cu (In, Ga) Se ₂ thin film and an n-type CdS thin film is formed. Thereafter, as shown in FIG. 5C, the semiconductor film 3 is divided into strips by a mechanical scribe method. After that, as shown in FIG. 5D, a transparent conductive film is formed as the second electrode film 4. Finally, as shown in FIG. 5E, the second electrode film 4 is divided into strips by a mechanical scribe method. In the thin-film solar cell module of FIG. 5E, each unit cell 5 is connected in series by connecting the second electrode film 4 of each unit cell 5 to the first electrode layer 2 of the adjacent unit cell 5. Connected.
[0004]
In such an integrated thin-film solar cell, versatility is enhanced by using a flexible substrate such as a stainless steel substrate. Further, when a flexible substrate is used, the substrate wound around a roll can be pulled out and a solar cell can be continuously formed thereon, which is advantageous in manufacturing.
[0005]
[Non-patent document 1]
The 13th European Photovoltaic Solar Conference (13TH EUROPEAN PHOTOVOLTAIC SOLAR CONFERENCE) 1995 p. 1451-1455
[0006]
[Problems to be solved by the invention]
In order to manufacture an integrated solar cell using a conductive substrate such as a metal flexible substrate, it is necessary to impart insulation to the surface of the substrate. In this case, an insulating film is formed on a metal substrate, and a unit cell is formed thereon. However, if the insulating property of the insulating film is insufficient due to pinholes or the like, the first electrode film and the metal substrate conduct, and the unit cells are short-circuited.
[0007]
When the adhesion between the insulating film formed on the metal substrate and the first electrode film is insufficient, the first electrode film cannot withstand the high temperature at the time of forming the semiconductor film, and the first electrode film is thermally stressed. The film may peel off.
[0008]
An object of the present invention is to provide a thin-film solar cell module having a novel structure in order to solve the problems of the above-described conventional technology.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a thin-film solar cell module of the present invention is a thin-film solar cell module including a plurality of unit cells connected in series, wherein the unit cells are formed of a conductive substrate and a conductive substrate. A first electrode layer, a semiconductor layer, and a second electrode layer arranged in this order from the conductive substrate side, and at least a part of an end of the conductive substrate is bent toward the second electrode layer side And the two adjacent unit cells are connected in series by contact between the end of one unit cell and the second electrode layer of the other unit cell. And
[0010]
In the thin film solar cell module, the end and the second electrode layer may be in contact with each other via a conductive material.
[0011]
In the thin-film solar cell module, the conductive substrate may be a stainless steel substrate.
[0012]
In the thin-film solar cell module, the semiconductor layer may include a compound semiconductor layer containing a group Ib element, a group IIIb element, and a group VIb element.
[0013]
In the thin-film solar cell module, the first electrode layer may be made of a metal containing molybdenum.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same portions are denoted by the same reference numerals, and duplicate description may be omitted.
[0015]
FIG. 1 shows a cross-sectional view of an example of the thin-film solar cell module of the present invention. The solar cell module 100 of FIG. 1 includes a plurality of unit cells 10 connected in series.
[0016]
Each unit cell includes a conductive substrate 11, a first electrode layer 12, a semiconductor layer 13, and a second electrode layer 14 that are sequentially stacked on the conductive substrate 11 from the substrate side. Note that another layer may be included between the layers as long as the layer functions as a solar cell. Further, an electrode for current collection may be formed on the second electrode layer 14.
[0017]
At least a part of the end 11 a of the conductive substrate 11 is bent toward the second electrode layer 14. The back surface of the bent end 11a is in direct contact with the second electrode layer 14 of the adjacent unit cell 10. In this way, two adjacent unit cells 10 are connected in series by electrically connecting the end 11a of one unit cell 10 and the second electrode layer 14 of the other unit cell 10. You. In this way, the plurality of unit cells 10 arranged in a line are connected in series. The end 11a and the second electrode layer 14 may be connected via a conductive material such as a metal paste or a conductive adhesive. With this configuration, the series resistance can be reduced. The angle α at which the end 11a is bent is generally in the range of 1 ° to 90 ° (preferably in the range of 1 ° to 60 °).
[0018]
As shown in FIG. 1, the end of the conductive substrate 11 of the unit cell 10 arranged at one (right side in FIG. 1) end of the unit cells 10 arranged in a row may not be bent. Further, the electrode layer and the semiconductor layer may be formed on the entire surface of the conductive substrate 11.
[0019]
FIGS. 2A and 2B are cross-sectional views of another example of the solar cell module of the present invention. In the solar cell module of FIG. 2A, the end portion of the end portion 11a is bent again toward the back surface side of the substrate. As a result, the end of the end 11a is substantially parallel to the surface of the second electrode layer 14, and the contact area between the end 11a and the second electrode layer 14 can be increased. The solar cell module of FIG. 2B has a configuration in which the angle α at which the end 11a is bent is set to about 90 ° in the solar cell module of FIG. 2A. Also in this case, the contact area between the end 11a and the second electrode layer 14 can be increased.
[0020]
Hereinafter, a method for manufacturing the solar cell module of the present invention will be described. First, a first electrode layer 12 is formed on a conductive substrate 11. The first electrode layer 12 is a metal film such as a Mo film, and can be formed by a sputtering method. The thickness of first electrode layer 12 is, for example, in the range of 0.3 μm to 2.0 μm. As the conductive substrate 11, a metal substrate such as a stainless steel substrate can be used. When a solar cell is manufactured using the roll-to-roll method, the conductive substrate 11 needs to have flexibility enough to be wound around a roll. When the conductive substrate 11 is a flexible stainless steel substrate, the thickness of the conductive substrate 11 is, for example, in a range of 20 μm to 200 μm.
[0021]
Next, a semiconductor layer 13 including a pn junction is formed on the first electrode layer 12. The semiconductor layer 13 includes a p-type semiconductor layer and an n-type semiconductor layer. As the p-type semiconductor, for example, a chalcopyrite structure semiconductor can be used, and specifically, a semiconductor containing a group Ib element, a group IIIb element, and a group VIb element can be used. More specifically, CuInSe ₂ (CIS), Cu (In, Ga) Se ₂ (CIGS) in which Ga is dissolved in Ga, or a semiconductor in which part of Se is replaced by sulfur can be used. . These can be formed by a vapor deposition method or a sputtering method. As the n-type semiconductor, for example, a compound containing at least a group II element and a group VIb element such as CdS, ZnO, Zn (O, OH), Zn (O, OH, S), or ZnMgO is used. be able to. These can be formed by a chemical bath deposition method or a sputtering method. The p-type semiconductor and the n-type semiconductor are stacked in this order from the substrate side. The p-type semiconductor layer functions as a light absorption layer, and the n-type semiconductor layer functions as a window layer.
[0022]
Next, a second electrode layer 14 is formed on the semiconductor layer 13. As the second electrode layer 14, a transparent conductive film such as a ZnO film, a ZnO: Al film, or an ITO film can be used, and can be formed by a sputtering method, a CVD method, or the like.
[0023]
These series of steps can be continuously performed by a roll-to-roll method. In the roll-to-roll method, each layer can be continuously formed by feeding a substrate wound on a roll. By using this method, a solar cell can be manufactured with high productivity and uniformity.
[0024]
Next, the conductive substrate 11 on which the thin-film solar cell is formed is cut into a fixed width to form a unit cell. Then, the end 11a of the conductive substrate 11 of the solar cell formed into a unit cell is bent as shown in FIG. 1 or FIG. The folding angle is from 1 ° to 90 °. Next, the back surface side of the bent end 11a is brought into contact with the second electrode layer 14 of the adjacent unit cell, and the adjacent unit cells are connected in series. At this time, the back side of the end 11a may be brought into contact with the second electrode layer 14 via a conductive paste or a conductive adhesive. Thus, the solar cell of the present invention can be easily manufactured.
[0025]
FIG. 3 shows a perspective view of another example of the solar cell module of the present invention. In the solar cell module of FIG. 3, the back surface of the end 11 a and the second electrode layer 14 are connected via the conductive paste 31. A grid electrode 32 is formed on the second electrode layer 14 to increase current collection efficiency. The grid electrode 32 can be formed by vapor deposition or screen printing using, for example, silver or aluminum.
[0026]
FIG. 4A shows a cross-sectional view of another example of the solar cell module of the present invention. FIG. 4B is a perspective view of a unit cell used in the module of FIG. In the solar cell module of FIG. 4A, only a part of the end 11a of the conductive substrate 11 is bent. In the example of FIG. 4A, the center portion of the end portion 11a is not bent, and the other portions are bent. The back surface of the bent portion of the end 11a is connected to the second electrode layer 14 of the adjacent unit cell 10. The unbent portion of the end 11a faces the back surface of the conductive substrate 11 of the adjacent unit cell 10 with the insulator 41 interposed therebetween. The insulator 41 can prevent a short circuit between the end 11a and the conductive substrate 11 of the adjacent unit cell. 3 and 4 can also be easily manufactured by the above-described manufacturing method.
[0027]
One thin-film solar cell formed on a conductive substrate can generate only a voltage of 1 V or less by itself. However, by connecting the unit cells in series as in the present invention, a solar cell module capable of generating an arbitrary voltage can be obtained.
[0028]
As described above, the embodiments of the present invention have been described by way of examples. However, the present invention is not limited to the above embodiments, and can be applied to other embodiments based on the technical idea of the present invention.
[0029]
【The invention's effect】
As described above, the thin-film solar cell module of the present invention has excellent versatility and is easy to manufacture.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of a thin-film solar cell module according to the present invention.
FIG. 2 is a sectional view showing another example of the thin-film solar cell module of the present invention.
FIG. 3 is a perspective view showing another example of the thin-film solar cell module of the present invention.
4A is a cross-sectional view showing another example of the thin-film solar cell module of the present invention, and FIG. 4B is a perspective view of a unit cell used therein.
FIG. 5 is a process cross-sectional view showing one example of a conventional method for manufacturing an integrated thin-film solar cell.
[Explanation of symbols]
100 solar cell module (thin film solar cell module)
Reference Signs List 10 unit cell 11 conductive substrate 11a end 12 first electrode layer 13 semiconductor layer 14 second electrode layer 31 conductive paste 32 grid electrode 41 insulator

Claims (5)

A thin-film solar cell module including a plurality of unit cells connected in series,
The unit cell includes a conductive substrate, a first electrode layer, a semiconductor layer, and a second electrode layer which are sequentially arranged on the conductive substrate from the conductive substrate side,
At least a part of an end of the conductive substrate is bent toward the second electrode layer,
The two adjacent unit cells are connected in series by contact between the end of one unit cell and the second electrode layer of the other unit cell. Battery module. The thin-film solar cell module according to claim 1, wherein the end portion and the second electrode layer are in contact with each other via a conductive material. 3. The thin-film solar cell module according to claim 1, wherein the conductive substrate is a stainless steel substrate. 3. The thin-film solar cell module according to claim 1, wherein the semiconductor layer includes a compound semiconductor layer including a group Ib element, a group IIIb element, and a group VIb element. 4. 3. The thin-film solar cell module according to claim 1, wherein the first electrode layer is made of a metal containing molybdenum.

Images