Solar module

A solar module is provided which has improved durability. A third wiring member (32a) includes a first portion (32a1), a second portion (32a2), and a third portion (32a3). In the first portion (32a1), metal foil (52) faces a solar cell (20). The first portion (32a1) is electrically connected to the solar cell (20). The second portion (32a2) is arranged on the solar cell (20) with the metal foil (52) facing the side opposite to the solar cell (20). The third portion (32a3) connects the first portion (32a1) and the second portion (32a2). A first wiring member (32b) electrically connects the second portions (32a2) of adjacent solar cell strings (10) to each other. The solar module (1) also includes an insulating sheet (60). The insulating sheet (60) is arranged between the first wiring member (32b) and the solar cell (20).

FIELD OF THE INVENTION

The present invention relates to a solar module.

BACKGROUND

Solar modules with back contact solar cells are conventionally known to be solar modules with improved photoelectric conversion efficiency. An example is described in Patent Document 1. The solar module described in Patent Document 1 includes a plurality of circuit boards with wiring provided on the surface. The back contact solar cells are arranged in one direction on the circuit boards. The solar cells are connected electrically to the wiring of the circuit boards. The circuit boards are arranged in another direction which is perpendicular to the one direction. Circuit boards adjacent to each other in the other direction are connected electrically via conductive members.

PRIOR ART DOCUMENTS

Patent Documents

SUMMARY

Problem Solved by the Invention

In recent years, there has been growing demand for solar modules with improved durability.

It is an object of the present invention to provide a solar module with improved durability.

Means of Solving the Problem

The solar module of the present invention includes a plurality of solar cell strings and a first wiring member. The solar cell strings are arranged in the one direction. The first wiring member is used to electrically connect adjacent solar cell strings to each other. The first wiring member is composed of metal foil. Each solar cell string has a plurality of solar cells, a second wiring member, and a third wiring member. The solar cells are arranged in another direction inclined with respect to the one direction. The second wiring member is bonded to the end portions of each of the adjacent solar cells. The second wiring member is used to connect adjacent solar cells to each other. The third wiring member is electrically connected to the end portion in the other direction of the solar cell positioned at the very end of the solar cells in the other direction. The third wiring member has resin film and metal foil arranged on the resin film. The third wiring member includes a first portion, a second portion, and a third portion. In the first portion, the metal foil faces the solar cell. The first portion is connected electrically to the solar cell. The second portion is provided on the solar cell with the metal foil facing the side opposite to the solar cell. The third portion connects the first portion and the second portion. The first wiring member is used to electrically connect the second portions of adjacent solar cell strings to each other. The solar module of the present invention also includes an insulating sheet. The insulating sheet is arranged between the first wiring member and the solar cell.

Effect of the Invention

The present invention is able to provide a solar module with improved durability.

DETAILED DESCRIPTION

The following is an explanation of examples of preferred embodiments of the present invention. The following embodiments are merely examples. The present invention is not limited by the following embodiments in any way.

Further, in each of the drawings referenced in the embodiments, members having substantially the same function are denoted by the same symbols. The drawings referenced in the embodiments are also depicted schematically. The dimensional ratios of the objects depicted in the drawings may differ from those of the actual objects. The dimensional ratios of objects may also vary between drawings. The specific dimensional ratios of the objects should be determined with reference to the following explanation.

As shown inFIG. 1andFIG. 2, the solar module1is provided with a plurality of solar cell strings10each having a plurality of solar cells20. More specifically, the solar module1includes a first through sixth solar cell string10a-10f. As shown inFIG. 2, the solar cell strings10are arranged between a first protecting member11and a second protecting member12. The first protecting member11is positioned on the side with the light-receiving surfaces20aof the solar cells20. The second protecting member12is positioned on the side with the back surfaces20bof the solar cells20. The second protecting member12is flexible. A sealing material layer13is provided between the first protecting member11and the second protecting member12. The solar cells20are sealed by the sealing material layer13.

The first protecting member11can be composed of a translucent member such as a resin substrate. The second protecting member12can be composed of a flexible member such as a resin sheet or a resin sheet containing interposed metal foil. The sealing material layer13can be composed of ethylene-vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), polyethylene (PE), or polyurethane (PU). The sealing material layer13preferably contains a non-crosslinked resin.

Each of the solar cell strings10has a plurality of solar cells20arranged in the x-axis direction, which is inclined with respect to (usually perpendicular to) the y-axis direction or the direction in which the solar cell strings10are arranged. As shown inFIG. 1andFIG. 3, each solar cell20has a photoelectric conversion unit23, and first and second electrodes21,22.

The photoelectric conversion unit23has first and second main surfaces23a,23b. The first main surface23aof the photoelectric conversion unit23constitutes the light-receiving surface20aof the solar cell20, and the second main surface23bconstitutes the back surface20bof the solar cell20.

A photoelectric conversion unit23is a member that generates carriers such as holes and electrons when exposed to light. The photoelectric conversion unit23may generate carriers when exposed to light only on the first main surface23a, or may generate carriers when exposed to light not only on the first main surface23abut also on the second main surface23b. In other words, the solar cells20may be bifacial solar cells.

There are no particular restrictions on the type of photoelectric conversion unit23that is used. The photoelectric conversion unit23can, for example, be composed using a crystalline silicon substrate.

A first electrode21for collecting one of either electrons or holes and a second electrode22for collecting the other of either electrons or holes are arranged on the second main surface23bof the photoelectric conversion unit23. In other words, the solar cells20are back contact solar cells.

There are no particular restrictions on the shape of either the first electrode21or the second electrode22. In the present invention, both the first electrode21and the second electrode22are comb-shaped. The first electrode21and the second electrode22are interdigitated. More specifically, the first electrode21and the second electrode22both have a plurality of finger portions21a,22aand a busbar portion21b,22b. Each of the finger portions21a,22aextends in the x-axis direction. Finger portions21a,22aare arranged at a predetermined interval in the y-axis direction, which is perpendicular to the x-axis direction.

The finger portions21aare connected electrically to busbar portion21b. Busbar portion21bis arranged on one side (the x1side) of the finger portions21ain the x-axis direction. Busbar portion21bis provided from one end to the other in the y-axis direction on the x1end portion of the solar cell20in the x-axis direction.

Similarly, the finger portions22aare connected electrically to busbar portion22b. Busbar portion22bis arranged on one side (the x2side) of the finger portions22ain the x-axis direction. Busbar portion22bis provided from one end to the other in the y-axis direction on the x2end portion of the solar cell20in the x-axis direction.

As shown inFIG. 1, adjacent solar cells20in the x-axis direction are connected electrically using a wiring member31in each of the solar cell strings10. More specifically, the first electrode21of one of the solar cells20adjacent to each other in the x-axis direction is connected electrically by a wiring member31to the second electrode22of the other solar cell20.

The wiring member31can be composed of metal foil, a metal foil laminate, metal foil whose surface is coated with solder, or a flexible printed circuit (FPC) board having an insulating film and wiring arranged on the insulating film. The metal foil and the wiring can be made of Ag or Cu.

The wiring member31and the back surface20bof a solar cell20are bonded via an adhesive layer (not shown). The adhesive layer can be composed of a cured resin adhesive, a cured resin adhesive containing a dispersed conductive material, or solder. The wiring member31is bonded to the end portion of the solar cell20in an x-axis direction. More specifically, the wiring member31is bonded only to the end portion of the solar cell20in an x-axis direction.

The first through sixth solar cell strings10a-10fare connected electrically via a wiring member32. More specifically, the solar cell20A at the farthest x2end of the first solar cell string10a, the solar cell20B at the farthest x2end of the second solar cell string10b, the solar cell20C at the farthest x2end of the third solar cell string10c, the solar cell20D at the farthest x2end of the fourth solar cell string10d, the solar cell20E at the farthest x2end of the fifth solar cell string10e, and the solar cell20F at the farthest x2end of the sixth solar cell string10fare each connected electrically by a wiring member32. The wiring member32electrically connects the first electrodes21of solar cells20A,20C and20E to the second electrodes22of solar cells20B,20D and20F.

In addition, the solar cell20H at the farthest x1end of the second solar cell string10b, the solar cell20I at the farthest x1end of the third solar cell string10c, the solar cell20J at the farthest x1end of the fourth solar cell string10d, and the solar cell20K at the farthest x1end of the fifth solar cell string10eare connected electrically by a wiring member32. The wiring member32electrically connects the first electrode21of solar cells20H and20J to the second electrode22of solar cells20I and20K.

A portion of wiring member32electrically connecting solar cells20H and20I, and a portion of wiring member32electrically connecting solar cells20J and20K create a first extraction electrode41. As shown inFIG. 2, the first extraction electrode41is drawn from the sealing material layer13and, more specifically, the solar module1. More specifically, the tip of the first extraction electrode41is drawn from the second protecting member12.

The wiring member32is actually composed of two wiring members32aand wiring member32b. The two wiring members32aare bonded via an adhesive layer40to the solar cell20, and are connected electrically to the first electrode21or the second electrode22. Wiring member32bis connected electrically to the two wiring members32a. Wiring member32ais arranged in the y-axis direction perpendicular to the x-axis direction from the y1end to the y2end of the end portion of the solar cell20in the x-axis direction. The wiring member32ais connected electrically to the solar cell at the far end in the x-axis direction of the solar cells20constituting a solar cell string10.

As shown inFIG. 4, the wiring member32ais composed of a flexible printed circuit board having a resin film51and wiring52. The resin film51can be made of a resin such as polyimide (PI) or polyethylene terephthalate (PET). The wiring52is arranged on the resin film51. The wiring52is connected electrically to the first electrode21or the second electrode22. The wiring52can be composed of metal foil made of at least one type of metal such as Cu or Ag.

The wiring member32ahas a first portion32a1, a second portion32a2and a bent portion32a3. The first portion32a1constitutes one end of the wiring member32a. The first portion32a1is arranged so that the wiring52faces the solar cell20. The first portion32a1is bonded to the back surface20bof the solar cell20.

The second portion32a2constitutes the other end of the wiring member32a. The second portion32a2is arranged so that the wiring52faces the side opposite to the solar cell20. At least a section of the second portion32a2is arranged on the first portion32a1. In other words, at least a section of the second portion32a2overlaps with the first portion32a1in the z-axis direction, which is the thickness direction of the solar cell20.

The bent portion32a3is connected to the first portion32a1and the second portion32a2. The bent portion32a3has a bent structure. In the bent portion32a3, the wiring52faces outside. The bent portion32a3is arranged on the back surface20bof the solar cell20. In other words, the bent portion32a3overlaps with the solar cell20in the z-axis direction. The bent portion32a3is formed by bending a flat wiring member.

Wiring member32bis connected electrically to the wiring52of the wiring member32ain the second portion32a2. In other words, the wiring member32bconnects the second portions32a2of solar cell strings10adjacent to each other in the y-axis direction. The wiring member32bis arranged so as to overlap with the second portion32a2in the x-axis direction. The wiring member32bmay be bonded to the wiring member32ausing a resin adhesive. In the present invention, it is bonded to the wiring member32ausing solder and is connected electrically to the wiring52of the wiring member32a. The wiring member32bis bonded to a portion of the wiring member32ain the y-axis direction. The ratio of the length of the portion of wiring member32abonded to wiring member32bin the y-axis direction relative to the length of wiring member32ain the y-axis direction ((length of wiring member32abonded to wiring member32bin the y-axis direction)/(length of wiring member32ain y-axis direction)) is preferably from 1/10 to 1, and more preferably from 1/10 to 1/2.

A portion of wiring member32bconstitutes extraction electrode41and is drawn from the solar module1.

In the present invention, the wiring member32bis composed of metal foil of at least one type of metal such as Cu or Ag. The thickness of the wiring member32bis greater than the thickness of the wiring52. The thickness of the wiring member32bis two or more times greater, and preferably 5 or more times greater, than the thickness of the wiring52.

The second electrode22of the solar cell20G at the farthest x1end of the first solar cell string10aand the first electrode21of the solar cell20L at the farthest x1end of the sixth solar cell string10fare connected electrically by wiring member33. Solar cells20G and20L are bonded to the wiring member33via an adhesive layer40.

Wiring member33has wiring member32aand wiring member33b. The wiring member32aconstituting a portion of wiring member33has a configuration that is substantially similar to the wiring member32aconstituting a portion of wiring member32. Wiring member32aconstituting a portion of wiring member33is bonded and connected electrically to the second electrode22of solar cell20G and the first electrode21of solar cell20L.

Wiring member33bis connected electrically to wiring member32aconstituting a portion of wiring member33. A portion of wiring member33bconstitutes extraction electrode42. The extraction electrode42is drawn from the sealing material layer13, more specifically, from the solar module1.

The wiring member33bis connected electrically to the wiring52in the second portion32a2of the wiring member32aconstituting a portion of wiring member33. The wiring member33bmay be bonded to the wiring member32ausing a resin adhesive. However, in the present embodiment, it is bonded to the wiring member32ausing solder and connected electrically to the wiring52of the wiring member32a. The wiring member33bis bonded to a portion of the wiring member32ain the y-axis direction.

In the present embodiment, the wiring member33bis composed of metal foil made of at least one type of metal such as Cu and Ag. The thickness of the wiring member33bis greater than the thickness of the wiring52. The thickness of the wiring member33bis 2 or more times greater, and preferably 5 or more times greater, than the thickness of the wiring52.

An insulating sheet60is arranged between the back surface20bof the solar cell20and the wiring members32b,33band extraction electrodes41,42made of metal foil. This can prevent shorting of the wiring members32b,33b, the extraction electrodes41,42and the electrodes21,22. The insulating sheet60can be made of the PI or PET resin used in the resin film51or can be made of EVA, PVB, PE or PU resin used in the sealing material layer13. The insulating sheet arranged between the wiring members32b,33band the solar cell20can be separate from the insulating sheet arranged between the extraction electrodes41,42and the solar cell20.

Here, the thermal expansion coefficient of the printed circuit board is different from the thermal expansion coefficient of the solar cell. As in the solar module described in Patent Document 1, this makes it so that a circuit board and a solar cell easily delaminate when the entire surface of a back contact solar cell is bonded to a circuit board.

In the solar module1, the wiring member31is not bonded to the entire surface of a solar cell20but only to the end portion of the solar cell20in the x-axis direction. In this way, it is difficult for a large amount of stress to occur between the wiring member31and the solar cell20when the temperature of the solar module1changes. This makes delamination of the wiring member31and the solar cell20less likely to occur.

Similarly, the wiring member32ais connected electrically to a solar cell20at the end portion of the solar cell20in the x-axis direction. The second portions32a2of wiring members32ain solar cell strings10arranged adjacent to each other in the y-axis direction are connected to each other electrically via a wiring member32bof metal foil. An insulating sheet60is arranged between the wiring member32band the solar cells20. The insulating sheet60insulates the wiring member32band the solar cells20. When this configuration is used, it is difficult for a large amount of stress to occur between the wiring member32band the solar cells20when the temperature of the solar module1changes. This makes delamination of the wiring member32band the solar cell20less likely to occur. As a result, a solar module1with improved durability can be realized.

In a configuration in which two wiring members32aare connected via a wiring member32b, a portion of a wiring member32bmay come into contact with the first electrode21or the second electrode22of the solar cell20. In order to prevent current leakage due to contact, an insulating sheet may be provided between the wiring member32band the solar cell20. However, when an insulating sheet is provided in this portion, a level difference occurs between the region in which wiring member32ais provided and the region in which wiring member32bis provided, and the wiring member32bconnected to wiring member32amay come off. This is likely to occur when the solar cells20are sealed inside the sealing material layer13.

In the present embodiment, an insulating sheet60is provided not only in the region in which wiring member32bis provided but also in the region in which wiring member32ais provided. As a result, the connection reliability between wiring member32aand wiring member32bcan be improved while insulating wiring member32band the solar cell20.

When this configuration is used, the size of the insulating sheet60can be reduced. In this solar module1, the wiring member32bis provided so as to overlap with the second portion32a2in the x-axis direction. As a result, the length of the region in which the second portion32a2and the wiring member32bare provided can be reduced in the x-axis direction. This further reduces the size of the insulating sheet60. The manufacturing costs of the solar module1can be lowered by reducing the size of expensive insulating sheets60.

In solar module1, the length of the second portions32a2in the x-axis direction of solar cell strings10aand10fpositioned to the outside in the y-axis direction is the same as the length of the second portions32a2in the x-axis direction of solar cell strings10b-10epositioned in the center in the y-axis direction. However, as shown inFIG. 6, the solar cell strings10of solar module2include solar cell strings10whose second portions32a2have different lengths in the x-axis direction. More specifically, the length of the second portions32a2in the x-axis direction of solar cell strings10aand10fpositioned to the outside in the y-axis direction is different from the length of the second portions32a2in the x-axis direction of solar cell strings10b-10epositioned in the center in the y-axis direction. The extraction electrode42is connected electrically to the longer second portions32a2of solar cell strings10b-10ein a portion closer to the center of the solar cell module2than the shorter second portions32a2of the solar cell strings10a,10f. The portion of the extraction electrode42on the side with the second portion32a2extends away from the second portion32a2in the y-axis direction. Unlike solar module1, solar module2does not require a bent portion in the portion of the extraction electrode42on the side with the second portion32a2. This reduces manufacturing costs associated with the extraction electrode42. As a result, the manufacturing costs of the solar module2can be reduced.

The present invention includes various embodiments not described herein. For example, the first and second electrodes may be busbarless electrodes which have finger portions but no busbar portion.

A solar module may also include a single solar cell.

The present invention includes many other embodiments not described herein. Therefore, the technical scope of the present invention is defined solely by the items of the invention specified in the claims pertinent to the above explanation.

KEY TO THE DRAWINGS

1: Solar module

10,10a-10f: Solar cell strings

13: Sealing material layer

20,20A-20L: Solar cells

20b: Back surface

23: Photoelectric conversion unit

31-33,32a,32b,33b: Wiring members

51: Resin film