WO2018004179A1 - Solar cell module - Google Patents

Abstract

The present invention relates to a solar cell module capable of replacing an electrical connection method of neighboring solar cells by using a metallic wire and a conductive pad so as to increase a light receiving area and minimize electrical resistance and, according to the present invention, the solar cell module comprises: a plurality of solar cells including a first solar cell and a second solar cell, and arranged so as to neighbor each other; and a plurality of metallic wires for electrically connecting a front electrode of the first solar cell and a rear electrode of the second solar cell, wherein: the solar cells comprise a front electrode and a rear electrode; the front electrode has a front collection electrode and a plurality of front conductive pads, and the rear electrode has a rear collection electrode and a plurality of rear conductive pads; the metallic wires are provided on a front conductive pad of the first solar cell and are extended therefrom so as to be provided on a rear conductive pad of the second solar cell; the plurality of front conductive pads are spaced and arranged on the front surface of the solar cells, and the plurality of rear conductive pads are spaced and arranged on the rear surface of the solar cells; and an area of the outermost front conductive pad or an area of the outermost rear conductive pad is larger than an area of an inner side front conductive pad or an area of an inner side rear conductive pad.

Description

Solar cell module

The present invention relates to a solar cell module, and more particularly, to a solar cell module capable of minimizing electrical resistance while increasing the light receiving area by replacing an electrical connection method of a neighboring solar cell with a metallic wire and a conductive pad. will be.

The solar cell module is composed of a plurality of solar cells (solar cell) is a device for receiving photovoltaic photovoltaic conversion. Each solar cell constituting the solar cell module may be referred to as a diode composed of a p-n junction.

In the process of converting sunlight into electricity by solar cells, when solar light is incident on the pn junction of solar cells, electron-hole pairs are generated, and electrons move to n layers and holes move to p layers by the electric field. Photovoltaic power is generated between the pn junctions, and when a load or a system is connected to both ends of the solar cell, current flows to generate power. The front and rear of the solar cell is provided with a front electrode and a rear electrode for collecting electrons and holes from the inside of the substrate.

On the other hand, the plurality of solar cells constituting the solar cell module is electrically connected, for example, the front electrode of the first solar cell is connected in the form of being connected to the rear electrode of the second solar cell. At this time, the front electrode and the back electrode of the neighboring solar cells are connected by a ribbon-shaped interconnector (refer to Korean Patent No. 1138174).

1A and 1B, when the front electrode and the rear electrode of the neighboring solar cell 110 are connected by the interconnector 120, the front electrode and the rear electrode include the bus bar electrode 111 in detail. The interconnector 120 connects the bus bar electrode 111 of the front electrode and the bus bar electrode 111 of the back electrode. The busbar electrode transfers carriers collected from the finger electrodes of the front electrode and the back electrode to the interconnector.

The structure of the solar cell module has been described above in general, but as described above, a bus bar electrode and an interconnector are essentially required for electrical connection of the solar cells. In addition, in order to reduce the electrical resistance, the busbar electrode and the interconnector occupy a small area compared to the solar cell area.

One of the conditions for increasing the photoelectric conversion efficiency of the solar cell is to increase the light receiving area. However, as mentioned above, since the busbar electrode and the interconnector occupy a considerable area, there is a problem in that the light receiving area is reduced, and the material required for forming the busbar electrode and the interconnector is also increased, thereby increasing the manufacturing cost. .

[Preceding technical literature]

[Patent Documents]

(Patent Document 1) Korean Registered Patent No. 1138174

The present invention has been made to solve the above problems, a solar cell module that can increase the light receiving area and minimize the electrical resistance by replacing the electrical connection method of the neighboring solar cells with metallic wires and conductive pads. The purpose is to provide.

A solar cell module according to the present invention for achieving the above object comprises a first solar cell and a second solar cell, a plurality of solar cells disposed adjacent; And a plurality of metallic wires electrically connecting the front electrode of the first solar cell and the rear electrode of the second solar cell. The solar cell includes a front electrode and a rear electrode. The front electrode is composed of a front collecting electrode and a plurality of front conductive pads, the rear electrode is composed of a rear collecting electrode and a plurality of rear conductive pads, the metallic wire is provided on the front conductive pad of the first solar cell is extended and 2 is provided on the rear conductive pad of the solar cell, the plurality of front conductive pads are spaced apart, disposed on the front of the solar cell, the plurality of rear conductive pads are spaced apart, disposed on the rear of the solar cell, the outermost The area of the front conductive pads or the area of the rear conductive pads is less than the area of the front conductive pads or the rear conductive pads disposed inside. It is characterized by large.

The number of front conductive pads and the number of rear conductive pads may be the same, or the number of rear conductive pads may be greater than the number of front conductive pads.

The plurality of front conductive pads and the plurality of rear conductive pads may be spaced apart from each other at equal intervals, and the distance between the front conductive pads or the rear conductive pads is 15 mm or less. In addition, the front conductive pad or the rear conductive pad disposed on the outermost side is disposed at 2.5mm or more away from the end of the solar cell substrate.

The number of metallic wires is less than six or more finger electrodes.

The area of the front conductive pad or the rear conductive pad disposed at the outermost side is 4 to 8 times larger than the area of the front conductive pad or the rear conductive pad disposed at the inner side.

The solar cell module according to the present invention has the following effects.

As the conventional ribbon and busbar electrodes are replaced with metallic wires and conductive pads, the number of metallic wires can be increased than the number of busbar electrodes, thereby improving the electrical characteristics of the solar cell module, and having a width greater than that of the busbar electrodes. By applying a narrow metallic wire, the light receiving area can be increased.

In addition, by optimally designing the number, area, and position of the conductive pads, adhesion characteristics between the metallic wires and the conductive pads and bowing characteristics of the solar cell can be improved.

1a and 1b is a block diagram of a solar cell module according to the prior art.

2 is a perspective view of a solar cell module according to an embodiment of the present invention.

3 is a reference diagram showing the front and rear of the solar cell according to an embodiment of the present invention.

4 is an experimental result showing the amount of warpage of the solar cell substrate according to the difference in the number of the front conductive pad and the rear conductive pad.

The present invention proposes a technique for replacing a ribbon-type interconnector in the construction of a solar cell module. As described in the background technology of the invention, a ribbon-type interconnector electrically connects the busbar electrodes of each solar cell. The present invention replaces the ribbon interconnection method by the combination of the metallic wire and the conductive pad.

Conductive pads are provided on the front and rear of each solar cell constituting the solar cell module, the conductive pad provided in each solar cell is electrically connected by a metallic wire. The conductive pads are provided on the front and rear surfaces of the solar cell, respectively, to transfer carriers collected by the electrodes on the front side and the electrodes on the rear side to the metallic wires.

In the case of a ribbon-type interconnector, two to four busbar electrodes are provided on the front and rear surfaces of the solar cell, and the same number of interconnectors as the busbar electrodes are applied. In contrast, in the case of the present invention, a plurality of conductive pads are spaced apart from and disposed on each of the front and rear surfaces of the solar cell substrate, and the metallic wires having a width smaller than the width of the bus bar electrodes are electrically connected to the plurality of conductive pads.

Since the width of the metallic wire is smaller than the width of the busbar electrodes, the number of metallic wires can be increased more than the number of busbar electrodes of the conventional interconnector method, and the number of busbar electrodes can be increased at the level of minimizing the reduction of light receiving area. As the metallic wires are disposed, the electrical connection between the solar cells can be improved.

In addition, the present invention proposes a technique for improving the adhesion characteristics between the metallic wire and the conductive pad and the bowing characteristics of the solar cell in the process of attaching the metallic wire and the conductive pad, that is, tabbing.

In consideration of the characteristics of the tabbing device, the heat transfer efficiency of the rear side is relatively lower than that of the front side of the solar cell, and the number of conductive pads disposed on the rear side is the same as the front side, or the number of conductive pads on the front side is designed to be larger. Through this, the adhesion property between the metallic wire and the conductive pad and the bending property of the solar cell can be improved. If the number of conductive pads on the front and back is different from each other, bending may occur.

As an additional method for improving the adhesion property between the metallic wire and the conductive pad, a technique of designing the area of the outermost conductive pad to be wider than that of other conductive pads (conductive pads disposed inside) is proposed. Along with this, the outermost conductive pad is disposed at a distance of 2.5 mm or more from the end of the solar cell substrate to reduce the possibility of cracking of the substrate.

Hereinafter, a solar cell module and a method of manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the drawings.

2 and 3, a solar cell module according to an embodiment of the present invention includes a plurality of solar cells 200, and the plurality of solar cells 200 are electrically connected by metallic wires 10. do.

Each solar cell 200 has a front electrode and a back electrode. The front electrode is provided on the front side of the solar cell 200, the rear electrode is provided on the rear side of the solar cell 200. Each of the front electrode and the back electrode is composed of a collecting electrode and a conductive pad. That is, the front electrode includes the front collection electrode 211 and the front conductive pad 212, and the rear electrode includes the rear collection electrode 221 and the rear conductive pad 222. The collecting electrode serves to collect a carrier generated by photoelectric conversion, and the conductive pad serves to transfer the carrier collected by the collecting electrode to the metallic wire 10.

The collecting electrodes may be configured to be spaced apart and arranged in parallel or may have a plate shape. In one embodiment, when the front electrode of the front-side photovoltaic solar cell or the front electrode and the rear electrode of the double-sided photovoltaic solar cell is configured, the collecting electrode is configured as a finger-line electrode spaced apart and arranged in parallel. In the case of forming the back electrode of the front-receiving solar cell, the collecting electrode may be configured in the form of a plate like an Al electrode (hereinafter referred to as a BSF electrode) that induces the formation of a back surface field. .

On the other hand, the conductive pads are repeatedly arranged at regular intervals on the front and rear surfaces of the solar cells regardless of the structure of the solar cells. In detail, the plurality of conductive pads are spaced apart at equal intervals in the horizontal and vertical directions. As described above, when the collection electrode forms the shape of a finger electrode, the finger electrode and the metallic wire 10 are orthogonal to each other, and a conductive pad is disposed at the intersection of the finger electrode and the metallic wire 10. In this case, the conductive pad may be provided at all intersection points of the finger electrode and the metallic wire 10 or may be selectively provided at some intersection points of all the intersection points. On the other hand, when the collecting electrode has a plate shape like the BSF electrode, the plurality of conductive pads are equally spaced apart in the horizontal direction and the vertical direction, and the BSF electrode is provided in an area where the conductive pad is not provided, and the plurality of metallic wires ( 10) forms a structure provided on the conductive pad.

The distance between the conductive pads is not limited, but within 15 mm in consideration of the adhesion characteristics of the metallic wire 10 and the conductive pad, the reduction of the light receiving area, the amount of the conductive material (eg, Ag) used to form the conductive pad, and the electrical characteristics. It is desirable to design. In addition, the finger electrode and the conductive pad may be composed of Ag as a main component, and the metallic wire 10 may be formed of copper (Cu) and tin (Sn) based metal compounds.

In configuring the front conductive pad 212 and the rear conductive pad 222, the area of the outermost conductive pad (hereinafter, referred to as the outermost conductive pad) is designed to be larger than the area of the conductive pad disposed inside. do. During the tabbing process, uniform heat is supplied to the inner conductive pads, so that the adhesive property of the metallic wire 10 and the conductive pad is good, but the outermost conductive pad is located at the edge of the cell. 10) the contact characteristics with the lowering and to compensate for this, it is necessary to design the area of the outermost conductive pad larger than the area of the inner conductive pad. In order to improve the adhesion characteristics of the metallic wire 10 and the outermost conductive pad, the outermost conductive pad may have an area of 4 to 8 times the area of the inner conductive pad. Only four to eight times the length can be designed.

In addition, in order to prevent cracking of the solar cell substrate 201, the outermost conductive pad may be disposed at a distance of 2.5 mm or more from the end of the solar cell substrate 201. The closer the position of the outermost conductive pad to the end of the substrate 201, the higher the output of the solar cell, but the greater the bending angle of the metallic wire, the greater the possibility of cracking at the end of the substrate. In the case of applying a conventional ribbon-shaped interconnector, one end of the busbar electrode is disposed 6 mm or more away from the end of the substrate. However, when the metallic wire of the present invention is applied, the outermost conductive pad is attached to the end of the substrate because of the flexible bending property of the metallic wire. It can be provided in a near position. In consideration of this point, the outermost conductive pad is preferably placed 2.5 to 6 mm away from the substrate end.

The number of front conductive pads 212 and the number of rear conductive pads 222 are preferably the same. The reason for designing the same number of front conductive pads 212 and rear conductive pads 222 is to prevent bending of the solar cell substrate. When the number of conductive pads on the front and rear surfaces of the substrate is different, the warpage phenomenon of the solar cell substrate may occur due to the difference in the coating amount of the conductive material forming the front and rear conductive pads. 4 illustrates the amount of warpage of the solar cell substrate according to the difference in the number of front conductive pads and the rear conductive pads. As shown in FIG. 4, the amount of warpage of the substrate increases as the difference in the number of front conductive pads and the rear conductive pads increases. It can be seen. It is most preferable to make the same number of front conductive pads and rear conductive pads to minimize the amount of warpage of the substrate. However, in the conventional structure, a tabbing device is located on the front side of the solar cell, and thus heat transfer efficiency to the rear side of the solar cell. There is a problem of falling, and in this case, the number of the rear conductive pads 222 may be larger than the front conductive pads 212.

In the state where the front electrode and the rear electrode of each solar cell 200 have the structure as described above, the metallic wire 10 connects the front electrode and the rear electrode of the neighboring solar cell 200. In an embodiment, when the first solar cell 200 and the second solar cell 200 are disposed, the metallic wire 10 may be formed of the front electrode of the first solar cell 200 and the second solar cell 200. The rear electrode is connected (or the rear electrode of the first solar cell 200 and the front electrode of the second solar cell 200 are connected by the metallic wire 10).

In detail, the metallic wire 10 disposed on the front conductive pad 212 of the first solar cell 200 extends to form a shape on the rear conductive pad 222 of the second solar cell 200. . The number of metallic wires 10 connecting the front electrode of the first solar cell 200 and the rear electrode of the second solar cell 200 is not limited, but it is 6 or more and the number of finger electrodes is less than the number. desirable.

[Description of the code]

10: metallic wire

200: solar cell 201: substrate

211: front collecting electrode 212: front conductive pad

221: rear collecting electrode 222: rear conductive pad

As the conventional ribbon and busbar electrodes are replaced with metallic wires and conductive pads, the number of metallic wires can be increased than the number of busbar electrodes, thereby improving the electrical characteristics of the solar cell module, and having a width greater than that of the busbar electrodes. By applying a narrow metallic wire, the light receiving area can be increased.

In addition, by optimally designing the number, area, and position of the conductive pads, adhesion characteristics between the metallic wires and the conductive pads and bowing characteristics of the solar cell can be improved.

Claims (11)

A plurality of solar cells including a first solar cell and a second solar cell and disposed adjacent to each other; And And a plurality of metallic wires electrically connecting the front electrode of the first solar cell and the rear electrode of the second solar cell. The solar cell includes a front electrode and a rear electrode, The front electrode is composed of a front collecting electrode and a plurality of front conductive pads, the rear electrode is composed of a rear collecting electrode and a plurality of rear conductive pads, The metallic wire is provided on the front conductive pad of the first solar cell and extended to be provided on the rear conductive pad of the second solar cell. A plurality of front conductive pads are spaced apart and disposed on the front of the solar cell, a plurality of rear conductive pads are spaced apart, disposed on the rear of the solar cell, The area of the front conductive pads or the area of the rear conductive pads disposed on the outermost side is greater than the area of the front conductive pads or the area of the rear conductive pads disposed inside. The solar cell module of claim 1, wherein the number of front conductive pads and the number of rear conductive pads are the same. The solar cell module of claim 1, wherein the number of rear conductive pads is greater than the number of front conductive pads. The solar cell module of claim 1, wherein the plurality of front conductive pads and the plurality of rear conductive pads are spaced apart from each other at equal intervals. The solar cell module of claim 1, wherein a distance between the front conductive pads and the rear conductive pads is 15 mm or less. The solar cell module of claim 1, wherein the front conductive pad or the rear conductive pad disposed at the outermost portion is disposed at a distance of 2.5 mm or more from an end of the solar cell substrate. The solar cell module of claim 1, wherein the number of metallic wires is 6 or more and less than the number of finger electrodes. The solar cell module of claim 1, wherein the solar cell is a double-sided light-receiving solar cell, and the emitter layer is a front-junction type double-sided light-receiving solar cell having an emitter layer disposed on a front surface of the substrate and a rear electric field layer provided on the rear surface of the substrate. . The solar cell module according to claim 1, wherein the solar cell is a double-sided light-receiving solar cell, and the emitter layer is a back-junction double-sided light-receiving solar cell having an emitter layer disposed on a rear surface of the substrate and a front electric field layer provided on the front surface of the substrate. The solar cell module according to claim 1, wherein the solar cell is a front light receiving solar cell. The solar cell according to claim 1, wherein an area of the front conductive pad or the rear conductive pad disposed at the outermost side is 4 to 8 times larger than the area of the front conductive pad or the rear conductive pad disposed inside. module.

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