JP2934366B2 - Solar cells with interconnectors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell, and more particularly to a structure of a solar cell with an interconnector for mounting on a satellite in space.

[0002]

2. Description of the Related Art As a power source of an artificial satellite or a space station, a solar cell panel in which solar cells are connected in parallel is used. Since the launch weight of a rocket for launching an artificial satellite is limited, it is desirable that the solar battery panel be lightweight. Some artificial satellites use tens of thousands of solar cells, and it is necessary to reduce the weight of solar cells alone.

FIGS. 2A and 2B are a sectional view and a rear view, respectively, of a conventional solar cell.

As shown in FIGS. 2A and 2B, electrodes 2 and 2 'are formed on the upper surface (light receiving surface) and the rear surface of the semiconductor substrate 1, respectively. The thickness of the electrodes 2, 2 'is about 5 to 10 [mu] m. In addition, an interconnector 3 for connecting to another solar cell is connected to the electrode 2. The interconnector 3 is usually about 20 to 50 μm thicker than the electrode. The connection between the electrode 2 and the interconnector 3 includes a method such as welding or soldering.

[0005] A cover glass 4 is further adhered to the upper surface of the semiconductor substrate 1 with an adhesive 5 in order to reduce radiation exposure in space and to block ultraviolet rays.

To bond the cover glass 4, an adhesive is applied to the light receiving surface of the solar cell or the back surface of the cover glass 4, and the solar cell and the cover glass 4 are bonded together. Since the outer space is in a vacuum, if air bubbles enter during bonding, the air bubbles become larger and the adhesive may peel off. For this reason, it is necessary to remove air bubbles in the adhesive. Specifically, a method has been adopted in which, after bonding a cover glass, defoaming is performed in a vacuum to remove air bubbles and then cure the adhesive.

[0007]

Meanwhile, in the conventional solar cell shown in FIG. 2, the thickness a of the connection portion of the interconnector 3 on the substrate and the thickness b other than the connection portion are the same. Therefore, when the interconnector 3 is connected, the thickness of the entire connecting portion is increased by the thickness of the interconnector 3, and c
It becomes like the thickness shown in. When the cover glass 4 is adhered to this solar cell, a difference occurs in stress due to the difference in thickness of the adhesive 5 on the connection part of the interconnector 3 and the thickness of the adhesive 5 other than on the connection part, and a space environment is generated. In an environment having a large temperature difference as described above, the adhesive 5 may peel off. Therefore, conventionally, the application amount of the adhesive 5 is increased to increase the thickness of the entire adhesive 5 and reduce the difference in stress.

[0008] However, this method has a problem that the weight of the solar battery cell increases because the amount of the adhesive is increased. Further, there is a problem that air bubbles remain when the adhesive 5 spreads because there is a step in the d portion. In order to remove these air bubbles, it is necessary to remove air bubbles by defoaming in a vacuum after bonding. There was a problem of cost.

[0009]

In order to achieve the above object, the present invention provides a semiconductor substrate, an interconnector connected to an upper end of the semiconductor substrate, and a connection between the upper surface of the semiconductor substrate and the interconnector. A cover glass adhered to the portion via an adhesive, in an interconnector-equipped solar cell comprising: such that the upper surface of the interconnector and the upper surface of the semiconductor substrate are substantially flush with each other;
The thickness of the interconnector connecting portion of the semiconductor substrate is formed to be thinner than a portion other than the connecting portion.

[0010]

Since the upper surface of the interconnector and the upper surface of the semiconductor substrate can be substantially flush with each other, the thickness of the adhesive applied thereon can be reduced, and the weight and cost of the solar cell can be reduced. In addition, since the thickness of the adhesive becomes uniform, high reliability can be obtained without stress. Furthermore, there is no step between the upper surface of the interconnector and the upper surface of the semiconductor substrate,
Alternatively, air bubbles are not involved when the adhesive is applied because of a small amount. Therefore, the defoaming step in vacuum after application of the adhesive, which is conventionally indispensable, becomes unnecessary, and the manufacturing process can be simplified.

[0011]

An embodiment of the present invention will be described with reference to FIG. FIGS. 1A and 1B are a cross-sectional view and a rear view, respectively, of a solar cell with an interconnector according to the present embodiment. The same symbols are given to the same functional parts as the conventional example shown in FIG. Here, points different from the conventional example will be mainly described.

As shown in FIG. 1, the solar cell of this embodiment is characterized in that the thickness c 'of the entire welded portion of the interconnector 3 is substantially the same as the thickness b' of the portion other than the welded portion. There is. In the present embodiment, the thickness of the welded portion connecting the inner interconnector 3 of the semiconductor substrate 1 'is formed thin. As this method, for example, there is a method of forming a pattern by photolithography and then partially etching the substrate by etching. Here, the thin portion is provided with the electrode 2 and the interconnector 3 so that the upper surface of the interconnector 3 is flush with the upper surface of the semiconductor substrate 1 'other than the welded portion.

Next, the cover glass 4 is adhered to the upper surface of the semiconductor substrate 1 'via an adhesive 5'.

By adopting the above-mentioned shape, the thickness of the adhesive 5 'can be made uniform, and the difference in stress, which has been a conventional problem, can be eliminated, and the reliability can be improved. Also, when applying the adhesive 4 ', as is clear from d', since there is no step as in the conventional case, air bubbles are not involved when the adhesive 4 'spreads, and the adhesive which has been indispensable in the past. The step of removing bubbles in a vacuum after application of the agent is not required, and the manufacturing process can be simplified. Furthermore, since there is no step, a direct bonding method that does not use an adhesive, which has not been conventionally adopted, can also be applied.

In addition, since the thickness of the adhesive can be reduced, that is, the weight of the adhesive can be reduced, the weight of the solar cell can be reduced and the cost can be reduced.

Even if the thickness of c 'is slightly larger than b', the same effect as described above can be obtained, though to a lesser extent, since the step can be made smaller than in the prior art.

[0017]

According to the present invention, the thickness of the adhesive for bonding the cover glass to the semiconductor substrate can be made uniform, the difference in stress, which has been a problem in the past, can be eliminated, and the reliability can be improved. In addition, the step of removing bubbles in a vacuum, which is indispensable in the past, becomes unnecessary, and the manufacturing process can be simplified. Further, since the amount of the adhesive can be reduced, the weight of the solar cell can be reduced and the cost can be reduced.

[Brief description of the drawings]

FIGS. 1A and 1B are a cross-sectional view and a rear view, respectively, of a solar cell with an interconnector according to an embodiment of the present invention.

FIGS. 2A and 2B are a cross-sectional view and a rear view, respectively, of a conventional solar cell with an interconnector.

[Explanation of symbols]

 1 'semiconductor substrate 3 interconnector 4 cover glass 5' adhesive

Claims (1)

(57) [Claims] 1. A semiconductor substrate, an interconnector connected to an upper end of the semiconductor substrate, a cover glass adhered on an upper surface of the semiconductor substrate and a connecting portion of the interconnector via an adhesive, In a solar cell with an interconnect comprising: a portion other than a connecting portion of the interconnector connecting portion of the semiconductor substrate so that an upper surface of the interconnector and an upper surface of the semiconductor substrate are substantially flush with each other. A solar cell with an interconnector characterized by being formed thinner than the above.