JPS60239067A - Solar cell element - Google Patents

Abstract

PURPOSE:To obtain a solar cell having excellent adhesive strength with leads and small shadow-loss of beams by forming a pattern with its width smaller than lead wires between divided bus bar electrodes. CONSTITUTION:An N<+> layer 13 is formed on a light-receiving surface 11 in a P type Si substrate 1, and a TiO2 antireflection film 4 and collectors 2 are superposed. A P<+> layer 14 and an electrode 3 are superposed on the back 12. Second pad electrodes 72, which are positioned among first pad sections 71 and pads 71 connected to the electrodes 2 and are smaller than the first pad sections 71, are formed to sections to which internal connecting leads for connecting solar cell elements in series are connected. Since bus bar electrodes are divided into a large number of pad sections 71, 72 in the structure, solder has excellent wettability and uniformity and also has a large adhesion area, thus resulting in large adhesive strength and high reliability on a temperature cycle. Since the pad sections have width smaller than the width of connecting leads, the shadow- loss of beams is reduced, and a device having high efficiency and high reliability is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to electrode structures on the light-receiving surface and back surface of a solar cell element.

[Background of the invention]

As shown in FIGS. 1 and 2, the conventional light-receiving surface electrode pattern of a solar cell element is formed by forming an n+ layer 13 on a light-receiving surface 11 on a p-type Bi substrate 1 by a method such as thermal diffusion. It has a structure in which an anti-reflection rIIA 4 and a current collecting electrode 2 are formed thereon by a printing method or a vapor deposition method. The pattern of the collecting electrode 2 is shown in FIG. 1(a).

As shown in (b), bus bar electrodes 7 are formed in the shape of parallel lines or a hexagonal mesh, and are used to connect elements in series to interconnector leads. However, with the comb pattern and honeycomb pattern electrodes shown in Fig. 1, when a solder dipping method or the like is used to connect the leads, the solder tends to flow to the bottom of the busbar electrode and become thick, resulting in poor adhesion when connecting the leads. The problem is that it cannot be obtained. Furthermore, in consideration of positional deviation during lead connection, it is necessary to make the busbar electrode width greater than the lead width, but if this is done, there is a problem that the light shielding area increases, leading to a decrease in electrical output.

Figures 2(a) and 2(b) show a structure in which the busbar electrode 7 is divided into small pieces to compensate for the above drawback, but since the bonding area between the electrode 7 and the IJ-board is small, the bonding strength is weak. .

[Purpose of the invention]

An object of the present invention is to provide a highly reliable solar cell element that has good solderability, excellent contact strength with leads, and low shadow loss of light.

[Summary of the invention]

A feature of the solar cell element of the present invention is that a pattern smaller than the lead line width is provided between the divided busbar electrodes.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below using the drawings shown as examples. Figure 3 shows a solar box 1 of the present invention (light-receiving surface) 1
l) N+ layer 1 by thermal diffusion method, ion implantation method, etc.
3 is formed and in contact with this reduces the reflectance of light,
91 layers 14 and electrodes 3 are formed by kt printing method etc. on T'+8''% oxide etc.
) shows the case where the electrode 2 has a comb-shaped pattern, and (b) shows the case where the electrode 2 has a honeycomb pattern. 71 and a second pad electrode 7 which is located between the first pad part 71 and which is smaller than the second pad part 71.
FIG. 3(d) is a plan view showing a state in which interconnector leads 9 are connected.

With this structure, since the bus bar electrode 7 is divided into a large number of first and second pad parts 71 and 72, the wettability and uniformity of the solder is good, and the bonding area is large, so it is easy to bond. It is possible to form a solar cell module that is strong and reliable enough to withstand harsh day and night heating and cooling cycles. Also,
Since each pad portion of the bus bar electrode is less than the width of the interconnect lead, there is an effect that shadow loss of light can also be reduced.

FIG. 4 is a plan view after interconnector leads are connected, showing another embodiment of the present invention. The first pad portion 71 of the busbar electrode 7 provided on the light-receiving surface 11 is provided with an R, and this electrode structure has the effect of further reducing shadow loss.

Although the present invention has been described above with respect to the electrode on the light-receiving surface, it can also be applied to an electrode pattern on the h-plane.

〔Effect of the invention〕

According to the present invention, it is possible to provide a highly efficient solar cell element that has good adhesion between interconnector leads and bus bar electrodes when connecting solar cell elements in series, is highly reliable, and has low shadow loss of light. The effect is great.

[Brief explanation of the drawing]

1 and 2 are a sectional view and a plan view showing a conventional solar cell element, FIG. 3 is a plan view and a sectional view of the light-receiving surface side showing an embodiment of the present invention, and FIG. 4 is a sectional view of the present invention. FIG. 7 is a plan view of the light-receiving surface side showing another embodiment of the invention. 1... SI board, 11... Light-receiving surface, 3... Back electrode, B... Current collecting electrode, 7...
・Busbar electrode, 71.72...Pad part of busbar electrode, 9...Interconnector lead. Agent Patent attorney Akio Takahashi Style 1 Illustration 2 Zu Kan 3 Figure (cL) (b) (G/) Continued from page 1 0 Inventors 1) Yasushi Akira 3-1 Saiwaimachi, Hitachi City
No. 1 Hitachi, Ltd. Hitachi Factory 390-

Claims (1)

[Scope of Claims] 1. A semi-integrated substrate having a PN junction, a thin wire-shaped first electrode in ohmic contact with a selected portion at a predetermined density on the entire surface of one main surface of the substrate, and one of the substrates. A bus bar electrode having a predetermined width provided on the main surface of the base body so as to intersect with the first electrode, and a second electrode in ohmic contact with a selected portion of the other main surface of the base body, A solar cell element characterized in that the busbar electrode is divided in its longitudinal direction. 2. The solar cell element according to claim 1, wherein some of the divided portions of the bus bar electrode have a width equal to or less than the width of the lead connected thereto.