JPH05129644A - Cover glass for solar cell - Google Patents

Abstract

PURPOSE:To decrease the weight of adhesive for fixing a cover glass to a solar cell by giving the cover glass an inwardly-curved light-receiving surface with an antireflection coating so that the warpage per unit length of the cover glass may be greater along its minor side than along its major side. CONSTITUTION:A cover glass 1 has an inwardly-curved light-receiving surface with an anti-reflection coating 6. The warpage per unit length of the cover glass is greater along its minor side than along its major side. The cover glass is fitted on a solar cell 3 with adhesive 2 in such a manner that the adhesive spreads from the center. This prevents lack of adhesive in inner portions, and as a whole, the adhesive becomes thin and uniform between the cover glass and the solar cell.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in cover cells for solar cells. It is particularly useful when used in space solar cells.

[0002]

2. Description of the Related Art As a solar cell for space use, one having a cover glass attached to the surface thereof is used to prevent radiation exposure and to block ultraviolet rays. The radiation exposure prevention performance of the cover glass is determined by its thickness when its specific gravity is constant. As a method of processing the cover glass to a predetermined thickness, there is generally a redraw method. The redraw method is a method of applying high heat to the cover glass and stretching the cover glass to a predetermined thickness.The processing cost is low, but the cover glass has a complicated warp shape in the process of stretching to the predetermined thickness. There is.

When a cover glass having such a complicated warp shape is adhered to a solar battery cell, if the application amount of the adhesive is small, the adhesive may not spread in a large warp portion of the cover glass. Also, in order to spread the adhesive throughout the cover glass, if the amount of adhesive applied is too large,
The thickness of the adhesive becomes unnecessarily large and the weight of the solar battery cell becomes large.

FIG. 4 is a cross-sectional view of a conventional example. When a cover glass 1 having the above-described complicated warp shape is bonded to the light-receiving surface side of a solar cell 3, it is 1
Drops or a few drops of the adhesive agent 2 are discharged onto the light-receiving surface of the solar cell 3 or the back surface of the cover glass 1, and both are pressure-bonded to each other. It is greatly affected by the warped shape of the glass 1. When the discharge amount of the adhesive 2 is small, as shown in FIG.
Of the cover glass 1 cannot follow the complicated warp shape of the cover glass 1, and a portion 4 where the adhesive does not adhere is generated in a portion where the warp is large. Further, when the discharge amount of the adhesive 2 is large, as shown in FIG. 6, the thickness of the adhesive 2 follows the complicated warp shape of the cover glass 1, but becomes thick as a whole, and the cover glass is bonded. In addition, the weight of the solar cell 3 increases.

[0005]

As shown in FIGS. 4 to 6, when a cover glass having a complicated warp shape is to be bonded to a solar battery cell, a large amount of adhesive must be dropped to cover glass. There is a manufacturing problem that the connecting agent does not spread all over, and if a large amount of adhesive is used, the weight of the solar cell to which the cover glass is adhered becomes large, and the weight reduction of the solar cell for space in recent years There is a problem that it violates the request of.

[0006]

In the present invention, an antireflection film is provided on the light receiving surface side of the cover glass, and the cover glass is curved so that the light receiving surface side becomes a recess. The amount of warpage per unit length of the cover glass was set to be larger in the short side direction than in the long side direction.

[0007]

According to the present invention, when the cover glass is bonded to the solar cell, the adhesive can be easily spread over the entire cover glass, and the thickness of the adhesive can be made relatively thin and uniform. Therefore, the weight of the solar battery cell to which the cover glass is adhered can be reduced.

[0008]

1 is a plan view of an embodiment of the present invention.
When the cover glass 1 is square, the dashed contour line 6 indicating the warp shape is circular, but when the cover glass 1 is rectangular, the contour line 6 is almost centered around the center of the cover glass 1 as shown in the figure. It has an elliptical shape. The contour lines 6 have a high density in the short side direction and a low density in the long side direction of the cover glass 1. That is, the cover glass 1 has a smaller warp per unit length in the long side direction than in the short side direction. This is to prevent the thickness of the adhesive at the ends in the long side direction from increasing as described later. The cover glass of this shape has, for example, a concave surface formed by cutting out the warped portion shown in FIG. 1 to a predetermined size when the cover glass 1 is drawn by the redraw method to a predetermined thickness. In Figure 2
It can be obtained by coating the antireflection film 5 as shown in FIG.

When the cover glass 1 shown in FIG. 1 is adhered to the solar cell 3 with the adhesive 2, X to X in FIG.
A cross-sectional view of the solar cell with a cover glass in the X'direction (long side direction) is shown in FIG. 2, and a cross-sectional view of the solar cell with a cover glass in the YY 'direction (short side direction) is shown in FIG. Since the cover glass 1 has a simple warp shape in which the antireflection film 5 side is concave, when the cover glass 1 is bonded to the solar battery cells 3 with the adhesive 2, the cover glass 1 is located outside the central portion of the cover glass 1. The adhesive 2 is spread and spread over the entire bonding surface of the cover glass 1. Therefore, it becomes difficult to cause a defect such as a portion 4 to which the adhesive is not attached on the inner surface of the cover glass 1 as shown in FIG. Also, cover glass 1
In the case of a rectangular shape, since the amount of warp per unit length in the long side direction is small, the adhesive thickness in the long side direction of the cover glass 1 has a warp per unit length as shown in FIG. Since it is small, it is relatively uniform. As shown in FIG. 3, the thickness of the adhesive in the short side direction of the cover glass is largely warped and greatly affected by the difference between the inside and outside, but is not uniform, but the absolute value itself of the variation in the adhesive thickness is small. Further, since the contour lines are substantially elliptical, the thickness of the adhesive at the peripheral portion can be made substantially equal in the long side direction and the short side direction. Therefore, as a whole, the adhesive 2 between the cover glass 1 and the solar cell 3
Can be thin and nearly uniform.

[0010]

As described above, when the cover glass according to the present invention is adhered to the solar battery cell, the surface of the cover glass coated with the antireflection film has a concave warp, so that the adhesives are different from each other. Even with a very small amount, it easily spreads over the entire adhesive surface of the cover glass. Further, when the shape of the cover glass is rectangular, the thickness of the adhesive becomes relatively uniform when the amount of warpage per unit length in the long side direction is smaller than that in the short side direction of the cover glass. Therefore, the weight of the adhesive can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line XX ′ when the cover glass of FIG. 1 is bonded to a solar battery cell.

FIG. 3 is a sectional view taken along line YY ′ when the cover glass of FIG. 1 is bonded to a solar battery cell.

FIG. 4 is a cross-sectional view of an example of a state in which a conventional cover glass and a solar cell are bonded together.

FIG. 5 is a cross-sectional view of an example of a conventional bonded state.

FIG. 6 is a cross-sectional view of another example of a conventional bonded state.

[Explanation of symbols]

 1 Cover Glass 2 Adhesive 3 Solar Cell 5 Antireflection Film 6 Contour

Claims (2)

[Claims] 1. A cover glass for a solar battery cell, which has an antireflection film on the light-receiving surface side and is curved so that the light-receiving surface side becomes a recess. 2. The cover glass according to claim 1, wherein the warp per unit length is larger in the short side direction than in the long side direction of the cover glass.