JPH069253B2 - How to connect solar cells - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a thin film solar cell having a thin film such as amorphous silicon formed on a flexible substrate.

[0002]

2. Description of the Related Art An a-Si solar cell using amorphous silicon (hereinafter referred to as a-Si) formed by glow discharge decomposition of silane gas has been studied by many researches for improving efficiency as a hope for a low-cost solar cell. Development is in progress. Since this a-Si solar cell is formed by vapor phase growth, it is suitable for increasing the area, and since it can be manufactured at a low temperature of 200 to 300 ° C., it has great flexibility in selecting the substrate material. Further, since the formed a-Si film has good adhesion to the substrate, even if a flexible substrate is adopted, characteristic deterioration due to bending of the substrate is hardly seen.

FIG. 7 shows an example of such a thin film solar cell. The substrate 1 is an insulating thin film having a thickness of 50 μm to 100 μm and made of a polymer material such as polyimide.
Sputtering of high melting point metal such as stainless steel, chromium, titanium, molybdenum, metal electrode 2 formed by electron beam evaporation, and diborane gas 1 for silane gas.
% Mixed reaction gas is controlled to 1 to 10 torr and decomposed in glow discharge plasma by high frequency electric field to 200 to 30
A p-type a-Si film 3 deposited on a substrate heated to 0 ° C. is laminated. Further, a non-doped a-Si layer having a thickness of about 0.5 μm was formed on the layer by glow discharge decomposition of silane gas.
The film 4 and the n-type a-Si film 5 are formed by the decomposition of the reaction gas in which 1% of Huoshin gas is mixed in the silane gas.
A transparent electrode 7 is deposited on the pin type a-Si layer 6 composed of the films 3, 4, and 5. The transparent electrode 7 is made of ITO (indium tin oxide), SnO ₂ (tin oxide) or the like,
It is formed on a thin film of 700 to 2000 liters by a method such as sputtering, electron beam evaporation, or thermal CVD.

FIG. 8 shows a solar cell in which the structure of FIG. 7 is connected in series, (a) is a plan view and (b) is a sectional view taken along the line AA. Three strip-shaped metal electrodes 2 are provided on the flexible insulating substrate 1 in the figure, and in addition to that, a terminal electrode 21 is also formed. These electrodes can be formed by using a metal mask during vapor deposition. Pi on this
Three regions of the a-Si layer 6 having an n-junction are separately provided in a strip shape. Each region of the a-Si layer 6 can be formed by dividing the a-Si layer formed on the entire surface of the substrate using the photoetching technique. Furthermore, a transparent electrode 7 is formed on the transparent electrode 7 in three separate parts by using a metal mask. In this way, the metal electrode 2,
a solar cell element 11 including an a-Si layer 6 and a transparent electrode 7,
12 and 13 are connected in series, and the output is the leftmost solar cell 1
It can be taken out from the end 20 of the first electrode and the terminal electrode 21.

[0005]

Light enters such a solar cell from the transparent electrode side. However, terminals 20, 21
Exists on the light incident side of the insulating substrate, and a lead wire must be connected to the terminals 20 and 21 on the light incident side when measuring the output characteristics of this solar cell. In this case, it is necessary to prevent the lead wire or the terminal at the tip thereof from blocking light. When the solar cells shown in FIG. 8 are further connected in series, the substrates 1 are adjacent to each other, and the electrode 21 of one solar cell is not shielded from the electrode 20 of the other solar cell by using a metal foil or a lead wire. Need to be connected. In the case of parallel connection, it is necessary to connect with the same consideration,
There is a limitation in connection means, which is a troublesome task.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of connecting a solar cell having terminals that can be easily connected without the above-mentioned drawbacks of connecting a solar cell provided on an opaque flexible substrate. To do.

[0007]

To achieve the above object, according to the present invention, a first solar cell having a solar cell element connected in series to the surface of a first flexible insulating substrate, In a method of connecting a solar cell having a second solar cell element having a solar cell element connected in series to the surface of a second flexible insulating substrate, the first flexible insulation of the first solar cell. The surface electrode formed directly on the end of the substrate and the surface electrode formed directly on the end of the second flexible insulating substrate of the second solar cell are viewed in the vertical direction. The first electrode is formed by connecting the surface electrode formed on the first solar cell and the surface electrode formed on the second solar cell by a conductive material after being aligned so as to at least partially overlap each other. The solar cell and the second solar cell are electrically connected It is assumed that the case.

[0008]

By the above method, the two solar cells are simply connected by simply using a conductive material. Also, the area where the lead wire or the terminal at the tip of the terminal blocks the light incident on the solar cell is greatly reduced.

[0009]

EXAMPLES Before entering the description of the examples of the present invention, the basic structure of the solar cells connected in the present invention will be described. FIG. 6 shows an example thereof, in which electrodes 22 are formed from a vapor-deposited metal layer on the surface of the flexible substrate 1 on the back side of the electrodes 20 and 21 at both ends of the solar cell. A hole 33 is formed in the electrode 22 through the substrate 1. The hole 33 is opened by a punch or the like before or after the electrode 22 is formed. The diameter of the hole 33 is about 200 μm to 1 mm, which is larger than the film thickness of the substrate. A conductive adhesive such as silver paste 3 is placed in the hole 33.
By dropping 4, the silver paste spreads, wets both the metal electrode 20 or both the terminal electrode 21 and the back electrode 22, and brings the front and back electrodes into a conductive state. As a result, the back electrode 2
2 can be used as a terminal and can be connected to an external lead wire without considering light shielding.

Next, a description will be given of an embodiment of the present invention. In FIG. 1, an a-Si solar cell which is the subject of the present invention is formed on a large-area flexible substrate. 1 (b) and 1 (c) are shown in FIG.
The XX line and the YY line cross section of (a) are each shown. The solar cell elements 10 are connected in series three by three and are arranged vertically and horizontally. As can be seen from FIG. 1C, the metal electrode 2 is continuous in the Y-Y line direction, and the a-Si layer 6 is also Y-.
Solar cells 10 that are continuous in the Y-line direction but are connected in series
A large hole 35 is formed between the rows. This hole 3
5 is formed simultaneously by patterning when forming the a-Si layer 6. Holes 36 smaller than the holes 35 are opened between the vertical and horizontal sides of the solar cells 10 connected in series through the metal electrode 2 and the substrate 1. The holes 36 opened between the solar cells in the YY line direction are conveniently concentric with the holes 35. The electrode 22 is formed on the side of the hole 36 opposite to the solar cell, as in the case of FIG. This solar cell is cut by a cutting line 41 or 42 with a cutter or scissors. The cutting line 41 separates the parallel-connected solar cell units arranged in the YY direction, and the cutoff line 42 separates the series-connected solar cell units formed in the XX line direction. When forming a solar cell module that requires a large amount of current and may have a low voltage, the cutoff line 42 is cut off, and if a module with a large voltage is needed, the cutoff line 41 is cut off to connect them. As a result, a module having an arbitrary voltage and current can be formed. In the example of FIG. 1, the 3-series connected thin film solar cell unit is drawn as the minimum unit that can be separated, but it is not fixed to this and the number of series of the minimum unit can be arbitrarily selected as necessary.

FIG. 2 shows an example of connecting the solar cell units separated in FIG. In this example, the cutting line 42 is used for separation, but the same is true for the cutting line 41. The hole 36 is cut into a semicircular cross section, and the two 3-series solar cell units 61 and 62 are cut into holes 36.
If the centers of the solar cell units 61 and 62 are overlapped and adhered with a conductive adhesive 34, the front surface metal electrodes 20 and the rear surface electrodes 22 of the terminals of the solar cell units 61 and 62 that are overlapped are brought into a common conductive state, and two 3 series Solar cell unit 61,62
Can be connected in series. In FIG. 2, the thickness direction is exaggeratedly drawn. Since the thickness of the substrate 1 is about 100 μm and the diameter of the hole 36 is about 0.5 mm, the solar cells 61 and 62 are stacked and conductive adhesive is applied from one side. The connection can be established simply by pouring the agent 34.

FIG. 3 shows an example different from FIG.
3B and 3C are respectively X-X line and Y- line in FIG.
It is a Y line sectional view. In this case, instead of the hole 36, two adjacent holes 37, 38 are provided. Cutoff lines 41, 42
Is designed to pass between these holes 37 and 38.
In FIG. 3, the a-Si layer 6 is not continuous in the Y-Y line direction, but as shown in FIG. 1, only the portions of the holes 37 and 38 may be made to be continuous and slightly larger. However, what is common to FIGS. 1 and 3 is that the transparent electrode 7 is discontinuous in the YY line direction, and there is no hole 36 or 37, 38. This is because the transparent electrode 7 and the metal electrode 2 do not short-circuit when separated.

FIG. 4 shows a connection state of the separated solar cell unit of FIG. In this case, since the holes 37 and 38 are circular, the positioning is easier than in the case of FIG. 2, and there is an advantage that the adhesive agent (not shown) does not leak out. FIG. 5 shows an example of a module in which a large number of thin film solar cell units cut as described above are connected. First, one unit 61 of the solar cell units 61 to 64 of appropriate size is attached to the glass plate 8 on the semiconductor thin film 6 side with, for example, an epoxy adhesive. Next, the next unit 62 is stacked so that the holes 36 in the case of the structure shown in FIG. 1 and the holes 37 and 38 in the case of the structure shown in FIG.
Glue the part that is in contact with the surface with adhesive in the same manner.
Next, a conductive adhesive is poured into the holes 36 or 37, 38 to electrically connect the overlapping electrodes. After the units are attached in this manner, the protective film 9 is adhered with, for example, epoxy resin. Such a module can be used as an interior such as a wallpaper by being attached to a glass window of a building, for example. In that case, since the light is taken into the room, it is necessary to use the flexible substrate 1 and the protective film 9 which are as transparent as possible. Alternatively, it is also effective to use the metal electrode 2 as a transparent electrode. Further, the shape of the metal electrode 2, the size and the arrangement of the holes 36, 37, 38 can be appropriately manufactured from a decorative point of view.

Although the conductive adhesive is used to connect the electrodes in the above embodiments, solder may be used if the flexible substrate has heat resistance.

[0015]

As described above, according to the present invention, since the connection between the output electrodes can be made on the back surface side of the substrate, there is no fear of blocking the incidence of light. Furthermore, if a large number of such solar cells are formed on a large area flexible substrate, cut to an arbitrary size, and connected by adhesion using the back electrode, the voltage and current capacity required by the customer can be reduced. The module can be easily formed. In addition, since the solar cells connected in this way can be attached to windows etc., it is possible to draw various patterns with the metal electrodes of the solar cells or through holes for connection when the decoration is focused. . Alternatively, if the metal electrode is changed to a transparent electrode, the effect of further increasing the degree of freedom in design can be obtained.

[Brief description of drawings]

FIG. 1 shows an a-Si solar cell to which the present invention is applied, which is formed on a large-area flexible substrate, (a) is a plan view,
(B) is a sectional view taken along line XX of (a), and (c) is a sectional view taken along line YY.

2 is a cross-sectional view of an essential part of an embodiment of the present invention showing a method for connecting solar cells cut out from the substrate of FIG.

FIG. 3 shows another example of an a-Si solar cell to which the present invention is applied, which is formed on a large-area flexible substrate, (a) is a plan view, (b) is X- of (a). X-ray sectional view, (c) YY
Line cross section

FIG. 4 is a cross-sectional view of an essential part of another embodiment of the present invention showing a method for connecting solar cells cut out from the substrate of FIG.

5 is a cross-sectional view of a main part of an example of a solar cell module including solar cells connected by the method shown in FIG. 2 or FIG.

FIG. 6 is a cross-sectional view showing an example of a basic structure of a solar cell connected in the present invention.

FIG. 7 is a sectional view of an a-Si solar cell.

FIG. 8 is an example of a series-connected solar cell, in which (a) is a plan view and (b) is a sectional view taken along the line AA of (a).

[Explanation of symbols]

 1 Flexible Insulating Substrate 10 Solar Cell Element 20 Front Electrode 22 Back Electrode 34 Conductive Adhesive 36 Hole 37 Hole 38 Hole 61 Solar Cell 62 Solar Cell

Claims (1)

[Claims] 1. A first solar cell having a solar cell element serially connected to a surface of a first flexible insulating substrate, and a solar cell element serially connected to a surface of a second flexible insulating substrate. A method of connecting a solar cell to connect a second solar cell element, the surface electrode directly formed on the end of the first flexible insulating substrate of the first solar cell, and the second The surface electrode directly formed on the end portion of the second flexible insulating substrate of the solar cell is aligned such that the positions of both electrodes overlap at least partially when viewed in the vertical direction, and then the first solar cell Electrically coupling the first solar cell and the second solar cell by connecting the surface electrode formed on the second solar cell and the surface electrode formed on the second solar cell by a conductive material. How to connect solar cells