Solar cell module

Disclosed is a solar cell module that comprises a solar cell including a first electrode and a second electrode on one main surface thereof, a wiring member electrically connected to the solar cell, and a resin adhesive layer bonding the solar cell and the wiring member to each other. Each of the first and second electrodes includes finger parts extending in one direction. The wiring member includes an insulating substrate, and a wiring disposed on the insulating substrate, and electrically connected to the finger parts of the first or second electrode. The resin adhesive layer includes an adhesive layer body made of a resin, and a conductive member disposed in the adhesive layer. A portion of the conductive member digs into at least one of the finger parts and the wiring.

TECHNICAL FIELD

The disclosure relates to solar cell modules.

BACKGROUND ART

As a solar cell module capable of achieving high output characteristics, a solar cell module including a back contact solar cell with both first and second electrodes provided on the back side thereof is known (see Japanese Patent Application Publication No. 2012-142456, for example, and others).

In the solar cell module described in Japanese Patent Application Publication No. 2012-142456, multiple solar cells are electrically connected to each other via a printed circuit board. Wirings of the printed circuit board are electrically connected to finger parts of a first or second electrode of the solar cell. This art further states that a printed circuit board and a solar cell may be connected to each other with a resin adhesive layer having anisotropic conductivity.

SUMMARY OF THE INVENTION

A solar cell module according to an embodiment includes a solar cell, a wiring member, and a resin adhesive layer. The solar cell includes first and second electrodes on one main surface side thereof. The wiring member is electrically connected to the solar cell. The resin adhesive layer bonds the solar cell and the wiring member to each other. Each of the first and second electrodes includes finger parts extending in one direction. The wiring member includes an insulating substrate and a wiring. The wiring is disposed on the insulating substrate. The wiring is electrically connected to the finger parts of the first or second electrode. The resin adhesive layer includes an adhesive layer body, and a conductive member. The adhesive layer body is made of resin. The conductive member is disposed in the adhesive layer body. A portion of the conductive member digs into at least one of the finger parts and the wiring.

DETAILED DESCRIPTION

Hereinafter, embodiments of solar cell modules are described. However, the embodiments described below are merely illustrative. The invention is not limited to the embodiments described below.

In the figures referred to for describing the embodiments, a member having a substantially same function is referred to with a same reference numeral. Figures referred to in the description of the embodiments are provided schematically. Therefore, the dimension ratio or the like of an object drawn in a figure may differ from that of a real object. The dimension ratio or the like of an object may be different between figures. The dimension ratio or the like of a specific object should be determined by considering the description given below.

As illustrated inFIG. 1, solar cell module1includes solar cells20. Solar cells20are electrically connected to each other via wiring member30.

Solar cells20are disposed within bonding layer13filled between first protective member11and second protective member12. First protective member11may be made of, for example, a glass plate, a resin plate, a ceramic plate, or the like. On the other hand, second protective member12may be made of a resin sheet, a resin sheet having a barrier layer such as a metal layer and an inorganic oxide layer, a glass plate, a resin plate, a ceramic plate or the like. Bonding layer13may is made of a crosslinkable resin such as ethylene and vinyl acetate copolymer (EVA), and a non-crosslinkable resin such as olefin.

As illustrated inFIG. 2, solar cell20includes light-receiving surface20a, and back surface20b. In solar cell20, light-receiving surface20ais oriented toward first protective member11, and back surface20bis oriented toward second protective member12. Light-receiving surface is a main surface mainly receiving light among a pair of main surfaces of the solar cell, and the other main surface forms the back surface.

Solar cell20includes photoelectric conversion body23. Photoelectric conversion body23generates carriers such as electrons or holes when receiving light. Photoelectric conversion body23may is made of, for example, a crystal semiconductor plate. Photoelectric conversion body23includes first and second main surfaces23a,23b. First main surface23aforms light-receiving surface20a. Second main surface23bforms back surface20b.

As illustrated inFIG. 3, first electrode21and second electrode22are disposed on second main surface23b. Each of first electrode21and second electrode22includes finger parts24, and bus bar part25. However, the first and second electrodes according to the invention may include finger parts only without having a bus bar part.

Finger parts24extend in the X axis direction. Finger parts24are disposed at intervals therebetween in the Y axis direction. Finger parts24of first electrode21and finger part24s of second electrode22are disposed alternately in the Y axis direction. Bus bar part25extends in the Y axis direction. Bus bar part25of the first electrode21is disposed at an end of x1 side in the X axis direction on second main surface23b. Bus bar part25of the second electrode22is disposed at an end of x2 side in the X axis direction on second main surface23b. In each of first and second electrodes21,22, finger parts24are electrically connected with bus bar part25.

Solar cells20adjacent in the X axis direction are electrically connected to each other via wiring member30disposed on second main surface23b. Specifically, in solar cells20adjacent in the X axis direction, first electrode21of one solar cell20, and second electrode22of other solar cell20are electrically connected to each other via wiring member30.

Wiring member30includes insulating substrate31and wiring32. Insulating substrate31may is made of, for example, a resin sheet or a ceramic plate. Wiring32is disposed on a surface, which orient to the second main surface23b, of insulating substrate31. Wiring32is electrically connected to finger part24of first electrode on one solar cell20, and finger part24of second electrode22on the other solar cell20. Specifically, wiring32includes first linear parts32a, second linear parts32b, and connection part32c. Connection part32cextends in the Y axis direction between adjacent solar cells20while extending from an end of one solar cell20on the x1 side in the X axis direction to an end of other solar cell20on the x2 side in the X axis direction. Connection part32ccovers at least portions of bus bar part25of first electrode21on one solar cell20, and bus bar part25of second electrode22in other solar cell20.

First linear parts32aare electrically connected to connection part32c. First linear parts32aextend in a convex shape from connection part32ctoward the x1 side in the X axis direction. First linear parts32aare arranged at intervals therebetween in the Y axis direction. At least some of first linear parts32aare disposed on finger parts24of second electrode22on the other solar cell20. First linear parts32aare electrically connected to finger parts24of second electrode22.

Second linear parts32bare electrically connected to connection part32c. Second linear parts32bextend in a convex shape from connection part32ctoward the x2 side in the X axis direction. Second linear parts32bare disposed at intervals therebetween in the Y axis direction. At least some of second linear parts32bare positioned on finger parts24of first electrode21on one solar cell20. Second linear parts32bare electrically connected to finger parts24of first electrode21.

Solar cell20and wiring member30are bonded to each other via resin adhesive layer40illustrated inFIG. 5. Resin adhesive layer40includes adhesive layer body41, and conductive members42. Adhesive layer body41is made of a resin. Specifically, adhesive layer body41is made of a cured resin adhesive. Conductive members42are disposed within adhesive layer body41. At least a surface layer of each conductive member42is made of a conductive material. That is, according to the invention, the conductive member may be conductive on at least a surface thereof, and does not need to have conductivity in the entirety. Conductive member42may be made of, for example, a metal particle, or inorganic oxide particle coated with a metal layer.

In solar cell module1, conductive member42digs into at least one of finger part24and wiring32(specifically, first or second linear part32a,32b). In other words, a portion of conductive member42is embedded within at least one of finger part24and wiring32. This provides an increased contact area between conductive member42and at least one of finger part24and wiring32, and thereby reduces electrical resistivity between wiring member30and solar cell20. Accordingly, improved output characteristics can be obtained. This also strengthens an anchoring effect by conductive member42, which makes electrical breakdown of wiring32and electrodes21,22less likely. Thus, improved reliability can be obtained. In order to obtain more improved output characteristics and reliability, it is preferable that conductive members42digs into both finger part24and wiring32. All conductive members42do not need to dig into at least one of finger part24and wiring32, but at least one conductive member42may dig into at least one of finger part24and wiring32.

In order to suitably dig conductive member42into finger part24and wiring32, it is preferable that at least one of finger part24and wiring32have a rough surface. This makes it possible to increase stress applied between conductive member42and finger part24or wiring32in bonding wiring member30and solar cell20together with pressure. This facilitates digging of conductive member42into finger part24and wiring32. Specifically, in solar cell module1, wiring32is provided with a rough surface such that conductive member42easily can be dug into wiring32.

In order to suitably dig conductive member42into finger part24and wiring32, the average particle diameter of conductive member42is preferably smaller than the average pitch of roughness (shortest distance between apexes of adjacent projection portions), more preferably 0.7 times or less and even more preferably 0.5 times or less than the average pitch of roughness. Specifically, the average particle diameter of conductive member42is preferably, for example, between 15 μm and 1 μm, more preferably between 10 μm and 2 μm, and even more preferably between 5 μm and 2 μm. The average pitch of roughness is preferably between 40 μm and 5 μm, and more preferably between 20 μm and 10 μm.

A method of providing roughness to the surface is not limited. For example, roughness may be provided by subjecting the surface to roughing treatment. The roughing treatment on the surface provides the rough surface, and also reduces hardness of the surface layer. This facilitates digging of conductive member42into finger part24and wiring32. Preferably used roughening treatments include, for example, a surface etching such as a multi-bond treatment.

In order to dig conductive member42into finger part24and wiring32, conductive member42preferably has a spherical shape. Here, the spherical shape means a shape having an aspect ratio of 2 or less, where the aspect ratio is a ratio of the major axis diameter to the minor axis diameter ((major axis diameter)/(minor axis diameter)).

In order to dig conductive member42into finger part24and wiring32, conductive member42preferably has hardness higher than a surface layer of at least one of finger part24and wiring32. Preferably, for example, conductive member42is made of copper or a copper alloy, and a surface layer of at least one of finger part24and wiring32is made of tin or a tin alloy. Specifically, in solar cell module1, conductive member42has hardness higher than the surface layer of finger part24. More specifically, conductive member42includes copper or a copper alloy, and the surface layer of finger part24is made of tin or a tin alloy. This facilitates digging conductive member42into the surface layer of finger part24. In solar cell module1, the portion of finger part24other than the surface layer is made of copper or a copper alloy.

In this way, embodiments described above provides a solar cell module having improved output characteristics.