JPS6141266Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a solar cell constructed by using a semiconductor wafer made of silicon or the like, and having a front electrode attached to the light irradiation surface and a back electrode attached to the back surface, in particular the shape of the surface electrode. This is related to.

Conventionally, this type of surface electrode includes one in which a large number of auxiliary thin wire lines c, c, etc. are concentrically branched from a central electrode line b provided with a lead wire outlet a, as shown in FIG. 1, for example. , the thin lines c, c... may be formed not only in concentric circles but also in angular shapes such as rectangles, or in various patterns such as lines c, c... extending radially from the center electrode line b. is already known.

However, in the above-mentioned patterns, a center electrode line b is formed in a straight line or in a star shape as shown in the figure over the entire surface of the light irradiation surface e of the semiconductor wafer d, and the center electrode line b is formed over the entire length of the line b. Since the structure is such that the auxiliary thin wire lines c, c... are branched out in a branching manner, in the case of the pattern shown in Fig. 1, the lead wire extraction portion a of the center electrode line b is
The current due to light irradiation collected on the auxiliary thin wire line c' that is distant from the line c' passes through the line c' and joins the end of the center electrode line b, and then flows through the same line b and reaches the lead wire extraction part a. Therefore, the carrier loss caused by this is large, and as a result, the short circuit current and fill factor, which are important characteristics of solar cells, are not satisfactory, and the conversion efficiency is only about 11.5%. There is.

In view of the above points, the present invention attempts to improve the characteristics of solar cells by forming an appropriate surface electrode pattern. In the present invention, as a surface electrode formed on the light irradiation surface 2, a lead wire extraction portion 3 with a wide width is provided near one side end of the light irradiation surface 2.
In addition, a desired plurality of wires are formed radially from the tip 3' and left and right side edges of the lead wire take-out portion 3 toward the periphery of the circular semiconductor wafer 1. The width straight lines 4, 4, . . . are pulled out at a distance from each other, and the medium width straight lines 4, 4, . is formed.

Furthermore, the medium-width straight lines 4, 4... are formed narrower than the lead wire extraction portion 3, and
From the left and right sides of the lines 4, 4..., auxiliary thin lines 5, 5..., which are even thinner than the lines 4, 4..., are pulled out laterally, and the lines 5, 5... In the illustrated example, the intersection angle α is approximately 45°, and the lines are drawn out in a straight line without intersecting each other. However, in the present invention, it is of course possible to achieve the purpose even if the lines are not in a straight line as shown in the figure. can.

In the present invention, as embodied in the above-mentioned embodiment, the surface electrode has a wide lead wire attachment part 3 formed near one end of the light irradiation surface 2, and a radial shape spaced apart from the attachment part 3. A desired plurality of medium-width straight lines 4, 4... drawn out and formed on the same line 4, 4.
Since it is composed of a large number of auxiliary thin wire lines 5, 5... branched from ..., the medium-width straight lines 4, 4... are connected to the straight lead wire attachment part 3 in a concentrated manner. Therefore, as shown in Figure 2, the path of current caused by photovoltaic force is
Since it is formed linearly from the terminal portion toward the lead wire take-out portion 3, it is formed to approximate the shortest distance, thereby reducing carrier loss.

Moreover, in this invention, the base portions of the medium width straight lines 4, 4 ... are not concentrated at one point A as shown in Figure 3, but are drawn out from the lead wire attachment portion 3 of a predetermined short length at a distance to the left and right.
Since an appropriate space is formed between the base portions, when forming the surface electrodes,
When the electrode is formed by vapor deposition or other means while masking areas other than the electrode formation area, extremely thin portions are not formed in the mask sheet used for masking as in the case of Figure 3. As a result, problems such as deterioration of workability due to extremely thin portions and improper vapor deposition of the surface electrode do not occur, and the loss can be significantly reduced.

Moreover, since the medium-width straight lines 4, 4, .
Compared to B', it is composed of a straight line B'' as shown in C in the same figure. Therefore, B'' is the shortest line connecting the end points X and X of these lines, and the carrier is correspondingly shorter. Since the loss in B' is reduced, and the area ratio of the surface electrode occupying the light irradiation surface is also minimized in case B', the area ratio of the light receiving surface is increased accordingly.

Here, for a 3-inch diameter cell according to the present invention,
Comparing its characteristics with conventional solar cells, it was found that the short circuit current increased by 10%, and the film factor increased by 5%.
~6% increase, compared to the conventional product with exchange efficiency of 11.5%
We were able to confirm 13.0%.

In addition, from the above experimental results, it is possible to expect a further increase in the effect if the solar cell is larger than the 3-inch cell.

[Brief explanation of the drawing]

Figure 1 shows one of the surface electrodes in a conventional solar cell.
FIG. 2 is a plan view of a solar cell showing an example of the surface electrode pattern according to the present invention; FIG. 3 is a plan view of a virtual surface electrode pattern exemplified to explain the effect of the pattern of the present invention. , A, B, and C of FIG. 4 are plan views showing examples of electrode lines for explaining the same effect. 1... Semiconductor wafer, 2... Light irradiation surface, 3...
Lead wire outlet, 4... Medium width straight line, 5...
Auxiliary thin line.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a solar cell in which a surface electrode is formed on the light irradiation surface of a semiconductor wafer, the surface electrode is formed with a wide lead wire extraction portion formed near one end of the light irradiation surface. , a desired plurality of medium-width straight lines drawn radially apart from each other from the extraction portion;
A surface electrode pattern of a solar cell consisting of a large number of auxiliary thin lines branched from the same straight line. (2) The auxiliary thin line is abbreviated to the medium-width straight line.
The electrode pattern of a solar cell according to claim 1 of the utility model registration, which is branched and drawn out in a straight line at an angle of 45 degrees.