JP5020179B2 - Solar cell module - Google Patents

Description

  The present invention relates to a solar cell module.

  A conventional solar cell element will be described with reference to FIG. In FIG. 11, 1 is a semiconductor substrate, 2 is a front surface side electrode, 3 is a back surface side electrode, 4 is an impurity diffusion layer, and 5 is an antireflection film.

  For example, an N-type impurity diffusion layer 4 is provided on the light-receiving surface side of a semiconductor substrate 1 made of P-type silicon, an antireflection film 5 and a surface-side electrode 2 are provided on the surface of the impurity diffusion layer 4, and a back-side electrode is provided on the back side. 3 is provided. As shown in FIG. 12, the surface-side electrode 2 includes a bus bar electrode 6 for connecting inner leads made of silver and solder, and a finger electrode 7 for current collection made of silver and solder. Further, as shown in FIG. 13, the back surface side electrode 3 is also composed of a bus bar electrode 8 for connecting an inner lead made of silver and solder, and a current collecting finger electrode 9 made of silver and solder ( For example, see Patent Document 1).

  Further, as shown in FIG. 14, the back surface side electrode 3 includes an output extraction portion 10 for connecting an inner lead made of silver and solder, and a current collecting portion 11 made of aluminum or the like. (For example, refer to Patent Document 2).

  Since the electrode area of the surface side electrode 2 of the solar cell element 13 becomes a light receiving loss, it is necessary to make the area as small as possible. However, if the surface side finger electrode 7 is not designed to sufficiently suppress the conductive resistance by increasing the cross-sectional area or increasing the number of the surface-side finger electrodes 7, the output will be reduced. Further, the front side bus bar electrode 6 is provided at a substantially middle point obtained by equally dividing the front side finger electrode 7 in the length direction. That is, when one surface-side bus bar electrode 6 is provided, it is substantially perpendicular to the intermediate point in the length direction of the finger electrode 7, and when two surface-side bus bar electrodes 6 are provided, it is approximately at a quarter position in the length direction of the finger electrode 7. Two are provided vertically. This is to reduce the loss due to resistance in the surface side finger electrode 7 as much as possible.

  In general, the surfaces of the front-side electrode 2 and the back-side electrode 3 are coated with solder from the viewpoint of ensuring workability in a later process and long-term reliability. In order to attach solder to the surfaces of the front-side electrode 2 and the back-side electrode 3, the solar cell element 13 is immersed in a vertical or horizontal direction in which the finger electrodes 7 and 9 are immersed in a bath containing molten solder. The method is cost-effective and frequently used.

  A method of connecting a plurality of solar cell elements 13 will be described with reference to FIG. FIG. 4A is a diagram for explaining the connection on the front surface side, and FIG. In FIG. 15, 12 indicates an inner lead. One end of the inner lead 12 is disposed over substantially the entire length on the bus bar electrode 6 on the front surface side, and a plurality of portions thereof are joined by heat welding or the like to be connected to the front side bus bar electrode 6. Are arranged over substantially the entire length of the back-side bus bar electrode 8 of the adjacent solar cell element 13, and the plurality of portions are similarly joined by thermal welding or the like to be connected to the back-side bus bar electrode 8. That is, in the conventional solar cell element 13, the front-side bus bar electrode 6 and the back-side bus bar electrode 8 are formed such that the center lines in the longitudinal direction thereof overlap.

As shown in FIG. 16, a plurality of such solar cell elements 13 are connected in series and in parallel between a translucent panel 14 made of glass or the like and a back surface protective material 15 made of a steel sheet containing film, Enclosed with a transparent filler 16 such as EVA (ethylene-vinyl acetate copolymer), and as shown in FIG. 17, a frame member 17 made of an extruded aluminum material is attached to the peripheral portion to form a solar cell module. Was.
JP 2002-43597 A JP 10-335267 A

  However, in this conventional solar cell module, when the front side bus bar electrode 6 and the inner lead 12 are thermally welded, and when the rear side bus bar electrode 8 and the inner lead 12 are thermally welded, the difference in thermal contraction rate between them is caused. There is a problem that peeling occurs between the semiconductor substrate 1 and the front surface side electrode 2 and the back surface side electrode 3 or between the front surface side electrode 2 and the back surface side electrode 3 and the inner lead 12.

  Further, as shown in FIG. 14, in the case of the back side electrode structure constituted by the current collecting part 11 made of aluminum or the like and the output extraction part 10 made of silver or the like, the thermal contraction rate of aluminum, silver and silicon is reduced. The stress due to the difference may remain, and the above problem is particularly likely to occur.

  The present invention has been made in view of such problems of the prior art, and when the electrodes on the front and back surfaces of the solar cell element are thermally welded with the inner leads, the front and back electrodes and the inner leads are formed. It is an object of the present invention to provide a solar cell element and a solar cell module that eliminate the occurrence of peeling between a semiconductor substrate and an electrode and peeling between an electrode and an inner lead due to a difference in thermal shrinkage.

The solar cell module of the present invention includes a substrate having a first surface and a second surface on the back side of the first surface, an electrode provided on the second surface side of the substrate, and the electrode And an electrode provided on the second surface side is disposed between the plurality of first portions connected to the inner lead and the plurality of first portions. A solar cell module having a second portion that electrically connects the plurality of first portions while avoiding a non-connection portion that is not connected to the inner lead, The longitudinal direction of the part is perpendicular to the longitudinal direction of the first part , and the second part is formed in a broken line shape .

  According to the solar cell module according to the present invention, the influence of the thermal contraction of the electrode of the solar cell element when the inner lead is connected is not affected over the entire length of the solar cell element, and the inner lead and the electrode are thermally welded. Furthermore, peeling between the semiconductor substrate and the electrode and peeling between the electrode and the inner lead can be prevented.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  The structure of the solar cell element according to the present invention is basically the same as that of a conventional solar cell element. That is, for example, an N-type impurity diffusion layer 4 is formed on the light-receiving surface side of the semiconductor substrate 1 made of P-type silicon, and an antireflection film 5 and a surface-side electrode 2 are formed on the surface of the impurity diffusion layer 4. Is provided. Further, a back side electrode 3 is provided on the back side of the semiconductor substrate 1. As shown in FIG. 12, the surface-side electrode 2 is composed of a surface-side bus bar electrode 6 for connecting inner leads made of silver and solder, and a surface-side finger electrode 7 for current collection made of silver and solder. Is done. Further, as shown in FIG. 13, the back side also includes a back side bus bar electrode 8 for connecting an inner lead made of silver and solder, and a back side finger electrode 9 for collecting current made of silver and solder. .

  Moreover, as shown in FIG. 14, the back surface side electrode 3 may be comprised by the output extraction part 10 for connecting the inner lead which consists of silver and solder, and the current collection part 11 which consists of aluminum.

  Such a solar cell element 13 has an N-type impurity diffusion layer 4 in which, for example, the P-type semiconductor substrate 1 is heat-treated in an N-type impurity atmosphere to diffuse the N-type impurities to the entire surface region to a certain depth. The antireflection film 5 is formed by a CVD method or the like, and a silver paste is screen printed on the front and back surfaces and baked to form the front surface side electrode 2 and the back surface side electrode 3.

  In FIG. 1, the structure of the back surface side electrode of the solar cell element 13 is shown. A plurality of back-side finger electrodes (first portions) 9 formed in a substantially parallel manner are connected by back-side bus bar electrodes (second portions) 8 formed substantially perpendicular to the back-side finger electrodes 9. The back side bus bar electrode 8 is provided at a position that does not overlap the longitudinal center line 18 of the front side bus bar electrode 6. That is, in FIG. 1, the back-side bus bar electrode 8 is provided so that the longitudinal center line 19 of the back-side bus bar electrode 8 is positioned outside the longitudinal center line 18 of the front-side bus bar electrode 6. ing.

  Thus, when the back side bus bar electrode 8 is provided at a position that does not overlap with the longitudinal center line 18 of the front side bus bar electrode 6, as will be described later, the inner leads connecting the plurality of solar cell elements 13 are: It becomes possible to connect to the finger 9 portion corresponding to the position of the longitudinal center line 18 of the bus bar electrode 6 on the front surface side, and the semiconductor substrate and the electrode are separated due to the difference in thermal contraction rate between the electrode and the inner lead. Further, peeling between the electrode and the inner lead can be prevented.

  The bus bar electrode 8 and the finger electrode 9 are formed so as to intersect substantially vertically. By doing in this way, the solder of the bus bar electrode 8 can be made to flow uniformly to the finger electrode 9.

  When the solar cell element is divided and modularized in order to obtain a high voltage value, it is desirable that the finger electrode 9 is not formed at the planned division position on the back surface side and in the vicinity thereof. That is, even if the finger electrode 9 and the inner lead 12 are connected by thermal welding or the like, the solder does not wrap around the surface, and even if the solder on the surface wraps around, the finger electrode 9 is separated from the end face of the solar cell element 13. This is because the problem of short-circuiting can be avoided.

  FIG. 2 is a diagram showing another structure of the back surface side electrode. In the solar cell element shown in FIG. 2, the finger electrode 9 is divided in the longitudinal direction, and the bus bar electrode 8 is formed on the same end side. As described above, when the bus bar electrode 8 is formed on the same end side of the divided finger electrode 9, the solar cell element 13 is immersed in the solder melt to form a solder layer on the surface of the bus bar electrode 8 and the finger electrode 9. In this case, it can be formed uniformly. That is, the problem that a lot of solder adheres to the bus bar electrode 8 on the lower side in the pulling direction does not occur.

  Moreover, as shown in FIG. 3, the finger electrode 9 can be tapered, or solder can be flowed more effectively by making it into an arrow shape as shown in FIG.

  In addition, when the solar cell element 13 is immersed in the solder bath in parallel with the finger electrode 9, as shown in FIG. 5, the bus bar electrode 8 is formed from the center, or as shown in FIG. You may form from outer periphery. Further, if it is outside the position where the inner lead 12 is connected, it may be formed so that the bus bar electrode 8 is positioned at the midpoint of the divided finger electrodes 9.

  The portion of the finger electrode 9 connected to the inner lead 12 is preferably formed directly on the semiconductor substrate 1. That is, even when applied to the back side electrode constituted by the current collector 11 made of aluminum or the like as shown in FIG. 14 and the output extraction portion 10 made of silver or the like, it is connected to the inner lead 12 of the finger electrode 9. This portion is formed directly on the semiconductor substrate 1. That is, portions of the plurality of finger electrodes 9 on the back surface that are on the line 19 that overlaps the longitudinal center line 18 of the bus bar electrode 6 on the front surface side are formed directly on the semiconductor substrate 1. By doing in this way, the adhesive strength of the finger electrode 9 can be improved and peeling can be prevented.

  In addition, as shown in FIG. 7, it is also an effective means for improving the electrode strength to make the portion of the finger electrode 9 connected to the inner lead 12 wider than the other portions. That is, a partially wide area is provided on the plurality of finger electrodes 9 on the back side on a line 19 that overlaps the longitudinal center line 18 of the front side bus bar electrode 6. At this time, the shape of the wide portion is not particularly limited. It may be formed in a quadrangular shape as shown in FIG. 7, or may be formed in a polygon such as a circle, a triangle, or a rhombus.

  Furthermore, as shown in FIG. 8, forming the finger electrodes 9 wider than the bus bar electrodes 8 is also an effective means for improving the electrode strength.

  The bus bar electrode 8 is preferably formed in a solid line over substantially the entire length. This is because the output can be taken out without connecting all of the finger electrodes 9 to the inner leads 12. However, as shown in FIG. 9, the bus bar electrode 8 may be formed in a broken line shape. However, at this time, it is necessary to connect the inner lead 12 to at least one finger electrode 9 connected to each bus bar electrode 8 in a broken line shape. Thus, by using the bus bar electrode 8 in a broken line shape, the amount of electrode material used for the bus bar electrode 8 can be reduced.

  Next, the structure of the solar cell module according to the present invention will be described with reference to FIG. The figure (a) is a figure which shows the wiring state which looked at the solar cell module from the front side, and (b) is a figure which shows the wiring state seen from the back side. The front side is the same as the conventional one, and one end of the inner lead 12 is arranged on substantially the entire length of the bus bar electrode 6 having an electrode structure optimized in consideration of the light receiving area and the resistance loss. Connect with.

 The other end of the inner lead 12 is disposed on the back side of the adjacent solar cell element 13. On the back side, the other end of the inner lead 12 is arranged on the finger electrode 9 instead of the bus bar electrode 8 and connected. Thereby, the influence of the thermal contraction of the electrode of the solar cell element 13 when the inner lead 12 is connected is not exerted over the entire length of the solar cell element 13, and the semiconductor substrate 1 and the electrode when the inner lead 12 and the electrode are heat-welded. Separation of the electrodes 8 and 9 and separation of the electrodes 8 and 9 and the inner lead 12 can be prevented.

  The inner lead 12 is preferably connected to the finger electrode 9 substantially perpendicularly. This is to reduce the connection area between one finger electrode 9 and the inner lead 12, and to prevent peeling between the semiconductor substrate 1 and the finger electrode 9 and peeling between the finger electrode 9 and the inner lead 12. It is.

It is a figure which shows the back surface structure of a solar cell element. It is a figure which shows the other back surface structure of a solar cell element. It is a figure which shows the structure which made the finger electrode of the solar cell element tapered. It is a figure which shows the structure which made the finger electrode of the solar cell element the arrow shape. It is a figure which shows the structure which provided the bus-bar electrode of the solar cell element in the center side. It is a figure which shows the structure which provided the bus-bar electrode of the solar cell element on the both sides of the board | substrate. It is a figure which shows the structure which provided the wide part in the finger electrode of the solar cell element. It is a figure which shows the structure which made the finger electrode of the solar cell element wider than the bus-bar electrode. It is a figure which shows the structure which made the bus-bar electrode of the solar cell element into the shape of a broken line. It is a figure for demonstrating the connection state of a solar cell element, (a) is a figure which shows the wiring state of the surface side, (b) is a figure which shows the wiring state of the back surface side. It is a figure for demonstrating the conventional solar cell element. It is a figure which shows the surface side electrode part of the conventional solar cell element. It is a figure which shows the back surface side electrode part of the conventional solar cell element. It is a figure which shows the back surface side electrode part of the other conventional solar cell element. It is a figure for demonstrating the connection state of the conventional solar cell element, (a) is a figure which shows the wiring state of the surface side, (b) is a figure which shows the wiring state of the back surface side. It is sectional drawing for demonstrating the structure of the conventional solar cell module. It is a top view for demonstrating the structure of the conventional solar cell module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate 2 ... Front side electrode 3 ... Back side electrode 4 ... Impurity diffusion layer 5 ... Antireflection film 6 ... Front side bus-bar electrode 7 ... Front side finger electrode 8 ... Back side bus bar electrode 9 ... Back side finger electrode 10 ... Output extraction part 11 ... Current collecting part 12 ... Inner lead 13 ... Solar cell element 14 ... Translucent Panel 15 ... Back surface protective material,
16 ... Filler 17 ... Frame member 18 ... Center line of inner lead to be connected

Claims (5)

A substrate having a first surface and a second surface on the back side of the first surface;
An electrode provided on the second surface side of the substrate;
An inner lead connected to the electrode;
The electrode provided on the second surface side includes a plurality of first portions connected to the inner leads and a non-connecting portion that is disposed between the plurality of first portions and is not connected to the inner leads. A solar cell module having a second part that avoids and electrically connects the plurality of first parts,
The part of the length of the second portion is perpendicular to the longitudinal direction of the first portion and the second portion, the solar cell module are formed like a dashed line. The plurality of first portions of the electrode provided on the second surface side and the non-connecting portion are disposed adjacent to each other along a longitudinal direction of the inner lead. 1. The solar cell module according to 1. The plurality of first portions of the electrode provided on the second surface side are divided in the longitudinal direction of the inner lead, and the first portions of the plurality of divided first portions are arranged on the same end side. the solar cell module according to claim 1 or 2, characterized in that a second portion. The said 1st part of the electrode provided in the said 2nd surface side is provided away from the edge part of the said 2nd surface of the said board | substrate, The any one of Claims 1-3 characterized by the above-mentioned. The solar cell module according to. Any said longitudinal inner leads, according to claim 1-4, characterized in that it is connected in the longitudinal direction substantially perpendicular of said plurality of first portions of the electrodes provided on the second surface A solar cell module according to claim 1.

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