WO2016065935A1

WO2016065935A1 - Solar cell module and manufacturing method thereof

Info

Publication number: WO2016065935A1
Application number: PCT/CN2015/084054
Authority: WO
Inventors: Zhiqiang Zhao; Zhanfeng Jiang; Long He
Original assignee: Byd Company Limited
Priority date: 2014-10-31
Filing date: 2015-07-15
Publication date: 2016-05-06

Abstract

A solar cell module (100) and a manufacturing method thereof are disclosed. The solar cell module (100) includes an upper cover plate (10), a front adhesive layer (20), a cell (31), a back adhesive layer (40) and a back plate (50) superposed in sequence, a secondary grid line (312) being disposed on a front surface of the cell (31), a transparent film (60) being disposed between the front adhesive layer (20) and the cell (31), a conductive wire (32) being disposed on a surface of the transparent film (60) corresponding to the cell (31), the conductive wire (32) being inserted into the transparent film (60) and exposed therefrom, and being formed of a metal wire (321) and connected with the secondary grid line (312), the transparent film (60) having a melting point higher than the melting point of the front adhesive layer (20) and the back adhesive layer (40), the metal wire (321) including a metal wire body and a connection material layer (322) coating the metal wire body, and the conductive wire (32) being connected with the secondary grid line (312) by the connection material layer (322).

Description

SOLAR CELL MODULE AND MANUFACTURING METHOD THEREOF

FIELD

The present disclosure relates to a field of solar cells, and more particularly, to a solar cell module and a manufacturing method thereof.

BACKGROUND

A solar cell module is one of the most important components of a solar power generation device. Sunlight irradiates onto a cell from its front surface and is converted to electricity within the cell. Primary grid lines and secondary grid lines are disposed on the front surface, and then a welding strip covers and is welded on the primary grid lines outputs the current. The welding strip, the primary grid lines and the secondary grid lines cover part of the front surface of the cell, which blocks out part of the sunlight, and the part of sunlight irradiating onto the primary grid lines and the secondary grid lines cannot be converted into electric energy. Thus, the welding strip, the primary grid lines and the secondary grid lines need to be designed as fine as possible in order for the solar cell module to receive more sunlight. However, the welding strip, the primary grid lines and the secondary grid lines serve to conduct current, and in terms of resistivity, the finer the primary grid lines and the secondary grid lines are, the smaller the conductive cross section area thereof is, which causes greater loss of electricity due to increased resistivity. Therefore, the welding strip, the primary grid lines and the secondary grid lines shall be designed to get a balance between light blocking and electric conduction, and to take the cost into consideration.

SUMMARY

The present disclosure is based on discoveries and understanding of the applicant to the following facts and problems.

In prior art, the primary grid lines and the secondary grid lines of the solar cells are made of expensive silver paste, which results in complicated manufacturing process of the primary grid lines and the secondary grid lines and high cost. When the cells are connected to form a module, the primary grid lines on the front surface of a cell are welded with back electrodes of another adjacent cell by a solder strip. Consequently, the welding of the primary grid lines is complicated, and the manufacturing cost of the cells is high.

In prior art, two primary grid lines are usually disposed on the front surface of the cell, and formed by applying silver paste to the front surface of the cell. The primary grid lines have a great width (for example, up to over 2mm) , which consumes a large amount of silver, and makes the cost high.

In prior art, a solar cell with three primary grid lines is provided, but this kind of solar cell still consumes a large amount of silver, and has a high cost. Moreover, three primary grid lines increase the shading area, which lowers the photoelectric conversion efficiency.

In addition, the number of the primary grid lines is limited by the solder strip. The larger the number of the primary grid lines is, the finer a single primary grid line is, and hence the solder strip needs to be narrower. Therefore, it is more difficult to weld the primary grid lines with the solder strip and to produce the narrower solder strip, and thus the cost of the welding rises up.

Consequently, from the perspective of lowering the cost and reducing the shading area, the prior art replaces the silver primary grid lines printed on the cell with metal wires, for example, copper wires. The copper wires are welded with the secondary grid lines to output the current. Since the silver primary grid lines are no longer used, the cost can be reduced considerably. The copper wire has a smaller diameter to reduce the shading area, so the number of the copper wires can be raised up to 10. This kind of cell may be called a cell without primary grid lines, in which the metal wire replaces the silver primary grid lines and solder strips in the traditional solar cells.

In prior art, there is a technical solution that the electrical connection of the metal wire and the cells is formed by laminating a transparent film pasted with metal wires and the cells, i.e. multiple parallel metal wires being fixed on the transparent film by adhesion, then being stuck on the cell, and finally being laminated to contact with the secondary grid lines on the cell. However, since the metal wires are pasted and fixed on the transparent film by a bonding layer whose melting point is relatively low, the bonding layer may melt or be softened in the laminating process, and thus the metal wires will drift to some extent.

However, the metal wires are fixed on the transparent film by the bonding layer, and the bonding layer tends to melt in the laminating process, which causes the drifting of the metal wire, and thus lowers the photoelectric conversion efficiency of the solar cell module.

Thus, in the field of solar cells, the structure of the solar cell is not complicated, but each component is crucial. The production of the primary grid lines takes various aspects into consideration, such as shading area, electric conductivity, equipment, process, cost, etc., and hence becomes a difficult and hot issue in the solar cell technology. In the market, a solar cell with two primary grid lines is replaced with a solar cell with three primary grid lines in 2007 through huge efforts of those skilled in the art. A few factories came up with a solar cell with four primary grid lines around 2014. The concept of multiple primary grid lines is put forward in the recent years, but still there is no fairly mature product.

The present disclosure seeks to solve at least one of the problems existing in the related art to at least some extent.

The present disclosure provides a solar cell without primary grid lines, which needs neither primary grid line nor sold strip disposed on the cells, and thus lowers the cost. The solar cell without primary grid lines can be commercialized for mass production, easy to manufacture with simple equipment, especially in low cost, and moreover have high photoelectric conversion efficiency.

According to a first aspect of embodiments of the present disclosure, a solar cell module includes an upper cover plate, a front adhesive layer, a cell, a back adhesive layer and a back plate superposed in sequence, a secondary grid line being disposed on a front surface of the cell, a transparent film being disposed between the front adhesive layer and the cell, a conductive wire being disposed on a surface of the transparent film corresponding to the cell, the conductive wire being inserted into the transparent film and exposed therefrom, and being formed of a metal wire and connected with the secondary grid line, the transparent film having a melting point higher than the melting point of the front adhesive layer and the back adhesive layer, the metal wire including a metal wire body and a connection material layer coating the metal wire body, and the conductive wire being connected with the secondary grid line by the connection material layer.

In the solar cell module according to embodiments of the present disclosure, the transparent film is disposed between the cell and the front adhesive layer, and the conductive wire is inserted in the transparent film in advance in the manufacturing process, such that the metal wire will not drift because the front and back adhesive layers melt in the laminating process, so as to guarantee the stability of connecting the conductive wire and the secondary grid line. Moreover, the metal wire body is provided with the connection material layer connected with the secondary grid line to improve the connection performance of the conductive wire and the secondary grid line, such that the solar cell module obtains relatively high photoelectric conversion efficiency.

According to a second aspect of embodiments of the present disclosure, a method for manufacturing a solar cell module includes: welding a conductive wire constituted by a metal wire into a transparent film, in which the metal wire comes out from the transparent film, and includes a metal wire body and a connection material layer applied to the metal wire body； superposing an upper cover plate, a front adhesive layer, the transparent film, the cell, a back adhesive layer and a back plate in sequence, and laminating them to obtain the solar cell module, in which the conductive wire and a secondary grid line of the cell are connected by the connection material layer； the transparent film has a melting point higher than the melting point of the front adhesive layer and the back adhesive layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a plan view of a solar cell array according to an embodiment of the present disclosure；

Fig. 2 is a transverse sectional view of a solar cell array according to an embodiment of the present disclosure；

Fig. 3 is a longitudinal sectional view of a solar cell array according to embodiments of the present disclosure；

Fig. 4 is a schematic diagram of a metal wire for forming a conductive wire according to embodiments of the present disclosure；

Fig. 5 is a plan view of a solar cell array according to another embodiment of the present disclosure；

Fig. 6 is a plan view of a solar cell array according to another embodiment of the present disclosure；

Fig. 7 is a schematic diagram of a metal wire extending reciprocally according to embodiments of the present disclosure；

Fig. 8 is a schematic diagram of two cells of a solar cell array according to embodiments of the present disclosure；

Fig. 9 is a sectional view of a solar cell array formed by connecting, by a metal wire, the two cells according to Fig. 8；

Fig. 10 is a schematic diagram of a solar cell module according to embodiments of the present disclosure；

Fig. 11 is a sectional view of part of the solar cell module according to Fig. 10；

Fig. 12 is a schematic diagram of a solar cell array according to another embodiment of the present disclosure.

Reference numerals:

100 cell module

10 upper cover plate

20 front adhesive layer

30 cell array

31 cell

31A first cell

31B second cell

311 cell substrate

312 secondary grid line

312A front secondary grid line

312B back secondary grid line

3121 edge secondary grid line

3122 middle secondary grid line

313 back electric field

314 back electrode

32 conductive wire

32A front conductive wire

32B back conductive wire

321 metal wire

322 connection material layer

33 short grid line

40 back adhesive layer

50 back plate

60 transparent film

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described in detail and examples of the embodiments will be illustrated in the drawings, where same or similar reference numerals are used to indicate same or similar members or members with same or similar functions. The embodiments described herein with reference to the drawings are explanatory, which are used to illustrate the present disclosure, but shall not be construed to limit the present disclosure.

Part of technical terms in the present disclosure will be elaborated herein for clarity and convenience of description.

According to embodiments of the present disclosure, A cell 31 includes a cell substrate 311, secondary grid lines 312 disposed on a front surface (the surface on which light is incident) of the cell substrate 311, a back electric field 313 disposed on a back surface of the cell substrate 311, and back electrodes 314 disposed on the back electric field 313. Thus, the secondary grid lines 312 can be called the secondary grid lines 312 of the cell 31, the back electric field 313 called the back electric field 313 of the cell 31, and the back electrodes 314 called the back electrodes 314 of the cell 31.

A cell substrate 311 can be an intermediate product obtained by subjecting, for example, a silicon chip to processes of felting, diffusing, edge etching and silicon nitride layer depositing. However, it shall be understood that the cell substrate 311 in the present disclosure is not limited to be formed by the silicon chip, but includes any other suitable solar cell substrate 311.

In other words, the cell 31 comprises a silicon chip, some processing layers on a surface of the silicon chip, secondary grid lines on a shiny surface (namely a front surface) , and a back electric field 313 and back electrodes 314 on a shady surface (namely a back surface) , or includes other equivalent solar cells of other types without any front electrode.

A cell unit includes a cell 31 and conductive wires 32 constituted by a metal wire S.

A a solar cell array 30 includes a plurality of cells 31 and conductive wires 32 which connect adjacent cells 31 and are constituted by the metal wire S. In other words, the solar cell array 30 is formed of a plurality of cells 31 connected by the conductive wires 32.

In the solar cell array 30, the metal wire S constitutes the conductive wires 32 of the cell unit, and extends between surfaces of the adjacent cells 31, which shall be understood in a broad sense that the metal wire S may extend between front surfaces of the adjacent cells 31, or may extend between a front surface of a first cell 31 and a back surface of a second cell 31 adjacent to the first cell 31. When the metal wire S extends between the front surface of the first cell 31 and the back surface of the second cell 31 adjacent to the first cell 31, the conductive wires 32 may include front conductive wires 32A extending on the front surface of the first cell 31 and electrically connected with the secondary grid lines 312 of the first cell 31, and back conductive wires 32B extending on the back surface of the second cell 31 and electrically connected with the back electrodes 314 of the second cell 31. Part of the metal wire S between the adjacent cells 31 can be called connection conductive wires.

In the present disclosure, the cell substrate 311, the cell 31, the cell unit, the cell array 30 and the solar cell module are only for the convenience of description, and shall not be construed to limit the present disclosure.

All the ranges disclosed in the present disclosure include endpoints, and can be individual or combined. It shall be understood that the endpoints and any value of the ranges are not limited to an accurate range or value, but also include values proximate the ranges or values.

In the present disclosure, the orientation terms such as “upper” and “lower” usually refer to the orientation “upper” or “lower” as shown in the drawings under discussion, unless specified otherwise； “front surface” refers to a surface of the solar cell module facing the light in practical application (for example, when the module is in operation) , i.e. a shiny surface on which light is incident, while “back surface” refers to a surface of the solar cell module back to the light in practical application.

In the following, a solar cell module 100 according to the embodiments of the present disclosure will be described with respect to the drawings.

As shown in Fig. 1 to Fig. 11, the solar cell module 100 according to the embodiments of the present disclosure includes an upper cover plate 10, a front adhesive layer 20, a cell 31, a back adhesive layer 40 and a back plate 50.

Specifically, the cell has secondary grid lines 312. The transparent film 60 is disposed between the front adhesive layer 20 and the cell 31. The conductive wire 32 is disposed on a surface of the transparent film 60 corresponding to the cell 31, and is inserted into the transparent film 60 and exposed therefrom. The conductive wire 32 is formed of a metal wire S and connected with the secondary grid line 312. The transparent film 60 has a melting point higher than the melting point of the front adhesive layer 20 and the back adhesive layer 40. The metal wire S includes a metal wire body 321 and a connection material layer coating he metal wire body 321. The conductive wires 32 and the secondary grid lines 312 are connected via the connection material layer 322 applied to the metal wire body 321.

In other words, the solar cell module 100 according to the embodiments of the present disclosure includes an upper cover plate 10, a front adhesive layer 20, a cell 31, a back adhesive layer 40 and a back plate 50 superposed sequentially from up to down. The cell 31 consists of a cell substrate 311 and the secondary grid lines 312 disposed on the cell substrate 311, and a transparent film 60 is disposed between the front adhesive layer 20 and the upper surface of the cell 31 (i.e. the shiny surface of the cell 31) . The conductive wires 32 are disposed on the lower surface of the transparent film 60, in which the conductive wires 32 are inserted in the transparent film 60 and exposed therefrom. The conductive wires 32 are constituted by the metal wire S and connected with the secondary grid lines 312. The metal wire S includes a metal wire body 321 and a connection material layer coating he metal wire body 321. The conductive wires 32 and the secondary grid lines 312 are connected via the connection material layer 322 applied to the metal wire body 321.

In the process of laminating the solar cell module 100, the transparent film 60 has a higher melting point than the front adhesive layer 20 and the back adhesive layer 40. In the laminating process, the front adhesive layer 20 and the back adhesive layer 40 melt, but the transparent film 60 will not melt, such that the metal wire S in the transparent film 60 is prevented from drifting, so as to obtain relatively photoelectric conversion efficiency of the solar cell module 100.

As shown in Fig. 4, the metal wire body 321 is coated with the connection material layer 322 to form the metal wire S, such as a conductive adhesive or a welding layer. The metal wire body 321 is welded with the secondary grid lines or the back electrodes via the connection material layer 322, so as to enhance the stability of connecting the metal wire with the secondary grid lines and/or the back electrodes, and to prevent the metal wire from drifting in the connection process which may affect the photoelectric conversion efficiency.

Consequently, in the solar cell module 100 according to the embodiments of the present disclosure, the transparent film 60 is disposed between the front adhesive layer 20 and the upper surface (i.e. the shiny surface) of the cell 31, and the conductive wire 32 is inserted in the transparent film 60 in advance in the manufacturing process, such that the metal wire will not drift because the front adhesive layer 20 and the back adhesive layer 40 melt in the laminating process, so as to guarantee the stability of connecting the conductive wire 32 and the secondary grid line 312. Moreover, the metal wire body 321 is provided with the connection material layer connected with the secondary grid line to form the metal wire S, and the metal wire S constitutes the conductive wires, so as to improve the connection performance of the conductive wire and the secondary grid line, such that the solar cell module obtains relatively high photoelectric conversion efficiency.

The front adhesive layer 20 and the back adhesive layer 40 are adhesive layers commonly used in the art. Preferably, the front adhesive layer 20 and the back adhesive layer 40 are polyethylene-octene elastomer (POE) and/or ethylene-vinyl acetate copolymer (EVA) . In the present disclosure, polyethylene-octene elastomer (POE) and/or ethylene-vinyl acetate copolymer (EVA) are conventional products in the art, or can be obtained in a method known to those skilled in the art.

In the embodiments of the present disclosure, the upper cover plate 10 and the back plate 50 can be selected and determined by conventional technical means in the art. Preferably, the upper cover plate 10 and the back plate 50 can be transparent plates respectively, for example, glass plates.

Other components of the solar cell module 100 according to the present disclosure are known in the art, which will be not described in detail herein.

It can be understood that in the present disclosure, the conductive wires 32 are inserted in the transparent film 60 disposed between the front adhesive layer and the upper surface of the cell 31, and located between the transparent film 60 and the upper surface of the cell 31. The conductive wires 32 in the embodiment can be understood as the front conductive wires 32A of the solar cell module 100, i.e. part of the conductive wires 32 connected with the secondary grid lines on the front surface of the cell 31 constituting the front conductive wires 32A.

In some specific embodiments of the present disclosure, there are multiple cells 31 to form the cell array 30, and adjacent cells 31 are connected by a plurality of conductive wires 322. The conductive wires 32 are constituted by the metal wire S which is electrically connected with the cell 31 and extends reciprocally between surfaces of the adjacent cells 31, so as to form the conductive wires.

When the cells 31 are connected in series by the metal wire S, the metal wire S extends reciprocally between a front surface of a first cell 31 and a back surface of a second cell 31 adjacent to the first cell 31.

In the embodiment, the transparent film 60 is be also disposed between the back adhesive layer 40 and the second cell, and the conductive wires 32 are disposed on the surface of the transparent film 60 opposite the second cell, and are inserted into the transparent film 60 and exposed therefrom. The conductive wire 32 is formed of a metal wire and connected with the secondary grid line 312. The conductive wires 32 are connected with the back electrodes 314 of the second cell, and part of the conductive wires 32 connected with the back electrodes 314 of the second cell constitute the back conductive wires 32B of the second cell.

In the embodiment, the connection material layer 322 is arranged in a position where the metal wire body for constituting the front conductive wire 32A and the secondary grid line 312 are connected, or coats the metal wire body along an entire length of the metal wire body constituting the front conductive wire 32A； the connection material layer 322 is arranged in a position where the metal wire body for constituting the back conductive wire 332B and the back electrode 314 are connected, or coats the metal wire body along an entire length of the metal wire body constituting the back conductive wire 32B.

That’s to say, in the solar cell module 100 of the present disclosure, the front conductive wires 32A are disposed on the front surface of the first cell 31, and the back conductive wires 32B are disposed on the back surface of the second cell 31. The front conductive wires 32A disposed on the front surface of the first cell 31 are provided with the connection material layer 322 by which the front conductive wires 32A are connected with the secondary grid lines 312 of the first cell 31； the back conductive wires 32B located on the back surface of the second cell 31 are also provided with the connection material layer 322, by which the back conductive wires 32B are connected with the back electrodes 314 of the second cell 31.

The connection material layer 322 may cover the whole metal wire body 321 completely, or may cover the position where the metal wire body 321 needs to be connected with the secondary grid lines 312 or the back electrodes 314.

It shall be noted that in the present disclosure, the metal wire S refers to a metal wire for extending reciprocally on the cells 31 to form the conductive wires 32, and consists of the metal wire body 321 and the connection material layer 322 coating the metal wire body 321. In other words, the conductive wires include the metal wire body 321 and the connection material layer 322 coating the metal wire body 321. In the embodiment of the present disclosure, unless specified otherwise, the metal wire refers to the metal wire S for extending reciprocally on the cells 31 to form the conductive wires 32.

Specifically, as for the back conductive wires 32B, the connection material layer 322 can be disposed at the position where the metal wire body 321 for constituting the back conductive wires 32B is connected with the back electrodes 314, or coat the metal wire body 321 along the entire length of the metal wire body 321 for constituting the back conductive wires 32B.

As for the front conductive wires 32A, the connection material layer 322 can be disposed at the position where the metal wire body 321 for constituting the front conductive wires 32A is connected with the secondary grid lines 312, or coat the metal wire body 321 along the entire length of the metal wire body 321 for constituting the front conductive wires 32A.

In the present disclosure, the conductive wires 32 (including the front conductive wires 32A and the back conductive wires 32B) can be inserted in the transparent film 60 by melting. The melting method includes: arranging the conductive wires 32 in the surface of the transparent film 60； heating the conductive wires 32 (e.g. electrical heating) , such that the contact portion of the transparent film 60 and the conductive wires 32 is softened or melted, so as to melt and fix the conductive wires 32 and the transparent film 60 together.

Preferably, a first end of the conductive wire is arranged on the lower surface of the first transparent film 60, and a second end of the conductive wire is arranged on the upper surface of the second transparent film 60, and then the conductive wire is heated (e.g. electrical heating) , such that the contact portion of the transparent film 60 and the conductive wires 32 is softened or melted, so as to melt and fix the conductive wires 32 and the transparent film 60 together. The first transparent film 60 whose lower surface is melted with the conductive wires faces a front surface of a first cell 31, such that the conductive wires 32 are connected with the secondary grid lines 312 on the front surface of the first cell； the second transparent film 60 whose upper surface is melted with the conductive wires faces a back surface of a second cell 31, such that the conductive wires 32 are connected with the back electrodes 314 on the back surface of the second cell； part of the conductive wires 32 welded with the secondary grid lines on the front surface of the first cell are called front conductive wires 32A, and part of the conductive wires 32 welded with the back electrodes on the back surface of the second cell are called back conductive wires 32B.

The conductive wires 32 are not completely inserted in the transparent film 60, and part thereof project from the transparent film 60. The part of the conductive wires 32 projecting from the transparent film 60 at least contains an alloy layer of low melting point, such that the conductive wires 32 are in ohmic contact with the secondary grid lines 312 on the shiny surface of the cell 31 or the back electrodes 314 on the back surface of the cell 31. The conductive wires 32 refer to the front conductive wires 32A, the back conductive wires 32B, or the combination.

In some specific embodiments of the present disclosure, the transparent film 60 is made of a transparent material with a melting point up to 160℃. In the embodiment, it can be guaranteed that the front adhesive layer 20 and the back adhesive layer 40 melt, but the transparent film 60 will not melt in the laminating process, such that the conductive wires 32 melted in the transparent film 60 will not drift.

Preferably, the transparent film 60 is formed with at least one of polyethylene glycol terephthalate (PET) , polybutylene terephthalate (PBT) and polyimide (PI) .

In the present disclosure, the transparent film has a thickness of 50 to 200μm, i.e. the transparent film 60 located on the front surface of the cell 31 and the transparent film 60 located on the back surface of the cell 31 have a thickness of 50 to 200μm respectively. Further, in order to improve the photoelectric conversion efficiency of the solar cell module 100, the transparent film 60 has a light transmittance of no less than 90％.

In the present disclosure, the connection material layer 322 is a welding layer or a conductive adhesive, and the welding layer is an alloy layer. In the following, the connection material layer 322 as the alloy layer will be illustrated in detail.

Specifically, in the present disclosure, the alloy contains Sn, Bi, and at least one of In, Ag, Sb, Pb and Zn.

Preferably, based on the total weight of the alloy, there are 15 to 60 weight percent of Bi, 30 to 75 weight percent of Sn, 0 to 20 weight percent of Cu, 0 to 40 weight percent of In, 0 to 3 weight percent of Ag, 0 to 20 weight percent of Sb, 0 to 10 weight percent of Pb, and 0 to 20 weight percent of Zn in the alloy.

Further, the alloy can be at least one selected from 50％Sn-48％Bi-1.5％Ag-0.5％Cu, 58％Bi-42％Sn, and 65％Sn-20％Bi-10％Pb-5％Zn.

Alternatively, the connection material layer 322 has a thickness of 1 to 100μm, and the metal wire body 321 has a cross section of 0.01 to 0.5mm². Preferably, a ratio of a thickness of the connection material layer 322 and a diameter of the metal wire body 321 is (0.02-0.5) : 1.

Alternatively, the connection material layer 322 is disposed at the position where the metal wire body 321 is in contact with the secondary grid lines 312 and/or the back electrodes 314. The connection material layer 322 is a welding layer or a conductive adhesive. More preferably, the welding layers are disposed at the positions where the metal wire body 321 is in contact with the secondary grid lines 312 and the back electrodes 314 of the cell 31. The alloy for forming the welding layer can be an alloy with a low melting point, for example a tin alloy. The tin alloy can be conventional in the art, for example, an alloy containing Sn, and at least one of Bi, Pb, Ag and Cu, specifically, SnBi, SnPb, SnBiCu, SnPbAg, etc, so as to avoid insufficient welding between the metal wire body 321 and the secondary grid lines 312 and/or the back electrodes 314 of the cell 31, and to obtain a relatively high photoelectric conversion efficiency of the solar cell module.

In some specific embodiments of the present disclosure, there are multiple cells 31 to constitute the cell array 30, adjacent cells 31 connected by the metal wire S that extends reciprocally between a surface of a first cell 31 and a surface of a second cell 31 adjacent to the first cell 31.

Specifically, the solar cell array 30 according to the embodiments of the present disclosure includes a plurality of cells 31. The adjacent cells 31 are connected with a plurality of conductive wires 32 which are constituted by a metal wire S. The metal wire S is electrically connected with the cells 31 and extends reciprocally between the surfaces of the adjacent cells 31.

The cell unit is formed by the cell 31 and the conductive wires 32 constituted by the metal wire S which extends on the surface of the cell 31. In other words, the solar cell array 30 according to the embodiments of the present disclosure are formed with a plurality of cell units； the conductive wires 32 of the plurality of cells are formed by the metal wire S which extends reciprocally between the surfaces of the cells 31.

It shall be understood that the term “extending reciprocally” in the application can be called “winding” which refers to that the metal wire S extends between the surfaces of the cells 31 along a reciprocal route.

In the present disclosure, it shall be understood in a broad sense that “the metal wire S extends reciprocally between surfaces of the cells 31. For example, the metal wire S may extend reciprocally between a front surface of a first cell 31 and a back surface of a second cell 31 adjacent to the first cell 31； the metal wire S may extend from a surface of the first cell 31 through surfaces of a predetermined number of middle cells 31 to a surface of the last cell 31, and then extends back from the surface of the last cell 31 through the surfaces of a predetermined number of middle cells 31 to the surface of the first cell 31, extending reciprocally like this.

In addition, when the cells 31 are connected in parallel by the metal wire S, the metal wire S can extend on front surfaces of the cells 31, such that the metal wire S constitutes front conductive wires 32A. Alternatively, a first metal wire S extends reciprocally between the front surfaces of the cells 31, and a second metal wire S extends reciprocally between the back surfaces of the cells 31, such that the first metal wire S constitutes front conductive wires 32A, and the second metal wire S constitutes back conductive wires 32B.

When the cells 31 are connected in series by the metal wire S, the metal wire S can extend reciprocally between a front surface of a first cell 31 and a back surface of a second cell 31 adjacent to the first cell 31, such that part of the metal wire S which extends on the front surface of the first cell 31 constitutes front conductive wires 32A, and part thereof which extends on the back surface of the second cell 31 constitutes back conductive wires 32B. In the present disclosure, unless specified otherwise, the conductive wires 32 can be understood as the front conductive wires 32A, the back conductive wires 32B, or the combination thereof.

The term “extending reciprocally” can be understood as that the metal wire S extends reciprocally once to form to two conductive wires 32 which are formed by winding a metal wire S. For example, two adjacent conductive wires form a U-shape structure or a V-shape structure, yet the present disclosure is not limited to the above.

In the solar cell array 30 according to the embodiments of the present disclosure, the conductive wires 32 of the plurality of cells 31 are constituted by the metal wire S which extends reciprocally； and the adjacent cells 31 are connected by the conductive wires 32. Hence, the conductive wires 32 of the cells are not necessarily made of expensive silver paste, and can be manufactured in a simple manner without using a solder strip to connect the cells. It is easy and convenient to connect the metal wire S with the secondary grid lines and the back electrodes, so that the cost of the cells is reduced considerably.

Moreover, since the conductive wires 32 are constituted by the metal wire S which extends reciprocally, the width of the conductive wires 32 (i.e. the width of projection of the metal wire on the cell) may be decreased, thereby decreasing the shading area of the conductive wires 32. Further, the number of the conductive wires 32 can be adjusted easily, and thus the resistance of the conductive wires 32 is reduced, compared with the primary grid lines made of the silver paste, and the photoelectric conversion efficiency is improved. Since the metal wire S extends reciprocally to form the conductive wires, when the cell array 30 is used to manufacture the solar cell module 100, the metal wire S will not tend to shift, i.e. the metal wire is not easy to “drift” , which will not affect but further improve the photoelectric conversion efficiency.

Therefore, the solar cell array 30 according to the embodiments of the present disclosure has low cost and high photoelectric conversion efficiency.

Moreover, it shall be noted that in the present disclosure, the conductive wires 32 can be constituted by the metal wire S which is coated with the conductive adhesive and extends reciprocally between the surfaces of the adjacent cells, or can be arranged by multiple metal wires in parallel to and spaced apart from each other. It is understandable for those skilled in the art that in the technical solution a plurality of individual metal wires are spaced apart from each other to form the primary grid lines of the traditional structure, which will not be described in detail.

In the following, the solar cell array 30 according to specific embodiments of the present disclosure will be described with reference to the drawings.

The solar cell array 30 according to a specific embodiment of the present disclosure is illustrated with reference to Fig. 1 to Fig. 3.

In the embodiment shown in Fig. 1 to Fig. 3, two cells 31 in the solar cell array 30 are shown. In other words, it shows two cells 31 connected with each other via the conductive wires 32 constituted by the metal wire S.

It can be understood that the cell 31 comprises a cell substrate 311, secondary grid lines 312 (i.e. front secondary grid lines 312A) disposed on a front surface of the cell substrate 311, a back electric field 313 disposed on a back surface of the cell substrate 311, and back electrodes 314 disposed on the back electric field 313. In the present disclosure, it shall be understood that the back electrodes 314 may be back electrodes of a traditional cell, for example, printed by the silver paste, or may be back secondary grid lines 312B similar to the secondary grid lines on the front surface of the cell substrate, or may be multiple discrete welding portions, unless specified otherwise. The secondary grid lines refer to the secondary grid lines 312 on the front surface of the cell substrate 311, unless specified otherwise.

As shown in Fig. 1 to Fig. 3, the solar cell array in the embodiment includes two

cells

31A, 31B (called a first cell 31A and a second cell 31B respectively for convenience of description) . The metal wire S extends reciprocally between the front surface of the first cell 31A (ashiny surface, i.e. an upper surface in Fig. 2) and the back surface of the second cell 31B, such that the metal wire S constitutes front conductive wires of the first cell 31A and back conductive wires of the second cell 31B. The metal wire S is electrically connected with the secondary grid lines of the first cell 31A (for example, being welded or bound by a conductive adhesive) , and electrically connected with the back electrodes of the second cell 31B.

In some embodiments, the metal wire extends reciprocally between the first cell 31A and the second cell 31B for 10 to 60 times to form 20 to 120 conductive wires. Preferably, as shown in Fig. 1, the metal wire extends reciprocally for 12 times to form 24 conductive wires 32, and there is only one metal wire. In other words, a single metal wire extends reciprocally for 12 times to form 24 conductive wires, and the distance of the adjacent conductive wires can range from 2.5mm to 15mm. In this embodiment, the number of the conductive wires is increased, compared with the traditional cell, such that the distance between the secondary grid lines and the conductive wires which the current runs through is decreased, so as to reduce the resistance and improve the photoelectric conversion efficiency. In the embodiment shown in Fig. 1, the adjacent conductive wires form a U-shape structure, for convenience of winding the metal wire. Alternatively, the present disclosure is not limited to the above. For example, the adjacent conductive wires can form a V-shape structure.

In some embodiments, preferably, the metal wire body 321 is a copper wire, but the present disclosure does not limited thereto. For example, the metal wire body 321 can be an aluminum wire. Preferably, the metal wire S has a circular cross section, such that more sunlight can reach the cell substrate to further improve the photoelectric conversion efficiency.

In some embodiments, preferably, before the metal wire contact the cells, the metal wire S extends under strain, i.e. straightening the metal wire. After the metal wire S is connected with the secondary grid lines and the back electrodes of the cell, the strain of the metal wire can be released, so as to further avoid the drifting of the conductive wires when the solar cell module is manufactured, and to guarantee the photoelectric conversion efficiency.

In some specific embodiments of the present disclosure, the secondary grid line has a width of 40 to 80μm and a thickness of 5 to 20μm； there are 50 to 120 secondary grid lines, a distance between adjacent secondary grid lines ranging from 0.5 to 3mm. thus, the structure of the secondary grid lines 312 is more reasonable, so as to obtain a larger sunlight area and higher photoelectric conversion efficiency.

Preferably, the binding force between the metal wire and the cells 31 ranges from 0.1N to 0.8N. That’s to say, the binding force between the conductive wires 32 and the cells 31 ranges from 0.1N to 0.8N. Preferably, the binding force between the metal wire and the cells ranges from 0.2N to 0.6N. so as to secure the welding between the cells and the metal wire, to avoid sealing-off of the cells in the operation and the transferring process and performance degradation due to poor connection, and to lower the cost.

Fig. 5 is a schematic diagram of a solar cell array according to another embodiment of the present disclosure. As shown in Fig. 5, the metal wire S extends reciprocally between the front surface of the first cell 31A and the front surface of the second cell 31B, such that the metal wire S constitutes front conductive wires of the first cell 31A and front conductive wires of the second cell 31B. In such a way, the first cell 31A and the second cell 31B are connected in parallel. Of course, it can be understood that preferably the back electrodes of the first cell 31A and the back electrodes of the second cell 31B can be connected via back conductive wires constituted by another metal wire S which extends reciprocally. Alternatively, the back electrodes of the first cell 31A and the back electrodes of the second cell 31B can be connected in a traditional manner.

Fig. 12 shows a schematic diagram of a solar cell array according to another embodiment of the present disclosure. As shown in Fig. 12, short grid lines 33 and secondary grid lines 312 are disposed at the front surface of the cell 31； the secondary grid lines 312 include middle secondary grid lines intersected with the conductive wires and edge secondary grid lines non-intersected with the conductive wires； the short lines 33 are connected with the edge secondary grid lines, and connected with the conductive wires or at least one middle secondary grid line. Preferably, the short grid lines 33 are perpendicular to the secondary grid lines 312.

Consequently, the short grid lines 33 are disposed at the edges of the shiny surface of the cell 31, so as to avoid partial current loss because the conductive wires 32 cannot reach the secondary grid lines 312 at the edges of the cell 31 in the winding process, and to further improve the photoelectric conversion efficiency of the solar cell module 100.

The solar cell array 30 according to another embodiment of the present disclosure is illustrated with reference to Fig. 6.

The solar cell array 30 according to the embodiment of the present disclosure comprises n×m cells 31. In other words, a plurality of cells 31 are arranged in an n×m matrix form, n representing a column, and m representing a row. More specifically, in the embodiment, 36 cells 31 are arranges into six columns and six rows, i.e. n＝m＝6. It can be understood that the present disclosure is not limited thereto. For example, the column number and the row number can be different. For convenience of description, in Fig. 6, in a direction from left to right, the cells 31 in one row are called a first cell 31, a second cell 31, a third cell 31, a fourth cell 31, a fifth cell 31, and a sixth cell 31 sequentially； in a direction from up to down, the columns of the cells 31 are called a first column of cells 31, a second column of cells 31, a third column of cells 31, a fourth column of cells 31, a fifth column of cells 31, and a sixth column of cells 31 sequentially.

In a row of the cells 31, the metal wire extends reciprocally between a surface of a first cell 31 and a surface of a second cell 31 adjacent to the first cell 31； in two adjacent rows of cells 31, the metal wire extends reciprocally between a surface of a cell 31 in a a^th row and a surface of a cell 31 in a (a+1) ^th row, and m-1≥a≥1.

As shown in Fig. 6, in a specific example, in a row of the cells 31, the metal wire extends reciprocally between a front surface of a first cell 31 and a back surface of a second cell 31 adjacent to the first cell 31, so as to connect the cells 31 in one row in series. In two adjacent rows of cells 31, the metal wire extends reciprocally between a front surface of a cell 31 at an end of the a^th row and a back surface of a cell 31 at an end of the (a+1) ^th row, to connect the two adjacent rows of cells 31 in series.

More preferably, in the two adjacent rows of cells 31, the metal wire extends reciprocally between the surface of the cell 31 at an end of the a^th row and the surface of the cell 31 at an end of the (a+1) ^th row, the end of the a^th row and the end of the (a+1) ^th row located at the same side of the matrix form, as shown in Fig. 6, located at the right side thereof.

More specifically, in the embodiment as shown in Fig. 6, in the first row, a first metal wire extends reciprocally between a front surface of a first cell 31 and a back surface of a second cell 31； a second metal wire extends reciprocally between a front surface of the second cell 31 and a back surface of a third cell 31； a third metal wire extends reciprocally between a front surface of the third cell 31 and a back surface of a fourth cell 31； a fourth metal wire extends reciprocally between a front surface of the fourth cell 31 and a back surface of a fifth cell 31； a fifth metal wire extends reciprocally between a front surface of the fifth cell 31 and a back surface of a sixth cell 31. In such a way, the adjacent cell bodies 31 in the first row are connected in series by corresponding metal wires.

A sixth metal wire extends reciprocally between a front surface of the sixth cell 31 in the first row and a back surface of a sixth cell 31 in the second row, such that the first row and the second row are connected in series. A seventh metal wire extends reciprocally between a front surface of the sixth cell 31 in the second row and a back surface of a fifth cell 31 in the second row； a eighth metal wire extends reciprocally between a front surface of the fifth cell 31 in the second row and a back surface of a fourth cell 31 in the second row, until a eleventh metal wire extends reciprocally between a front surface of a second cell 31 in the second row and a back surface of a first cell 31 in the second row, and then a twelfth metal wire extends reciprocally between a front surface of the first cell 31 in the second row and a back surface of a first cell 31 in the third row, such that the second row and the third row are connected in series. Sequentially, the third row and the fourth row are connected in series, the fourth row and the fifth row connected in series, the fifth row and the sixth row connected in series, such that the cell array 30 is manufactured. In this embodiment, a bus bar is disposed at the left side of the first cell 31 in the first row and the left side of the first cell 31 in the sixth row respectively； a first bus bar is connected with the conductive wires extending from the left side of the first cell 31 in the first row, and a second bus bar is connected with the conductive wires extending from the left side of the first cell 31 in the sixth row.

As said above, the cell bodies in the embodiments of the present disclosure are connected in series by the conductive wires–the first row, the second row, the third row, the fourth row, the fifth row and the sixth row are connected in series by the conductive wires. As shown in the figures, alternatively, the second and third row, and the fourth and fifth rows can be connected in parallel with a diode respectively to avoid light spot effect. The diode can be connected in a manner commonly known to those skilled in the art, for example, by a bus bar.

However, the present disclosure is not limited to the above. For example, the first and second rows can be connected in series, the third and fourth rows connected in series, the fifth and sixth rows connected in series, and meanwhile the second and third rows are connected in parallel, the fourth and fifth connected in parallel. In such a case, a bus bar can be disposed at the left or right side of corresponding rows respectively.

Alternatively, the cells 31 in the same row can be connected in parallel. For example, a metal wire extends reciprocally from a front surface of a first cell 31 in a first row through the front surfaces of the second to the sixth cells 31.

In some specific embodiments of the present disclosure, for a typical cell with a dimension of 156mm×156mm, the solar cell module has a series resistance of 380 to 440mΩ per 60 cells. The present disclosure is not limited to 60 cells, and there may be 30 cells, 72 cells, etc. When there are 72 cells, the series resistance of the solar cell module is 456 to 528mΩ, and the electrical performance of the cells is better.

In some specific embodiments of the present disclosure, for a typical cell with a dimension of 156mm×156mm, the solar cell module has an open-circuit voltage of 37.5-38.5V per 60 cells. The present disclosure is not limited to 60 cells, and there may be 30 cells, 72 cells, etc. The short-circuit current is 8.9 to 9.4A, and has nothing to do with the number of the cells.

In some specific embodiments of the present disclosure, the solar cell module has a fill factor of 0.79 to 0.82, which is independent from the dimension and number of the cells, and can affect the electrical performance of the cells.

In some specific embodiments of the present disclosure, for a typical cell with a dimension of 156mm×156mm, the solar cell module has a working voltage of 31.5-32V per 60 cells. The present disclosure is not limited to 60 cells, and there may be 30 cells, 72 cells, etc. The working current is 8.4 to 8.6A, and has nothing to do with the number of the cells.

In some specific embodiments of the present disclosure, for a typical cell with a dimension of 156mm×156mm, the solar cell module has a conversion efficiency of 16.5-17.4％, and a power of 265-280W per 60 cells.

A method for manufacturing the solar cell module 100 according to the embodiments of the present disclosure will be illustrated with respect to Fig. 7 to Fig. 9.

The method includes the steps of welding a conductive wire 32 constituted by a metal wire S into a transparent film, in which the metal wire comes out from the transparent film, and includes a metal wire body 321 and a connection material layer 322 applied to the metal wire body 321； superposing an upper cover plate 10, a front adhesive layer 20, the transparent film 60, the cell 31, a back adhesive layer 40 and a back plate 50 in sequence, and laminating them to obtain the solar cell module 100, in which the conductive wire 32 is connected with the secondary grid line 312 of the cell 31 via the connection material layer 322, and the transparent film 60 has a melting point higher than the melting point of the front adhesive layer 20 and the back adhesive layer 40.

In other words, when the solar cell module 100 of the present disclosure is manufactured, the conductive wires 32 are arranged in the surface of the transparent film 60, and are constituted by the metal wire S which consists of a metal wire body 321 and a connection material layer 322 coating the metal wire body 321. Then the conductive wires 32 are heated (e.g. electrical heating) , such that the contact portion of the transparent film 60 and the conductive wires 32 is softened or melted, so as to melt and fix the conductive wires 32 and the transparent film 60 together, and the metal wire comes out from the transparent film 60.

Then, the upper cover plate 10, the front adhesive layer 20, the transparent film 60, the cell 31, the back adhesive layer 40 and the back plate 50 are superposed in sequence. The secondary grid lines 312 on the front surface of the cell 31 are in direct contact with the conductive wires 32. The upper cover plate 10, the front adhesive layer 20, the transparent film 60, the cell 31, the back adhesive layer 40 and the back plate 50 are laminated to obtain the solar cell module 100 said above in the present disclosure.

The upper cover plate 10, the front adhesive layer 20, the transparent film 60, the cell 31, the back adhesive layer 40 and the back plate 50 are superposed in sequence. The secondary grid lines 312 on the front surface of the first cell 31 are in direct contact with and connected with the conductive wires 32 via the connection material layer 322. The back electrodes 314 on the back surface of the second cell 31 are in direct contact with and connected with the conductive wires 32 via the connection material layer 322. The upper cover plate 10, the front adhesive layer 20, the transparent film 60, the cell 31, the back adhesive layer 40 and the back plate 50 are laminated to obtain the solar cell module 100 said above in the present disclosure.

Specifically, as shown in Fig. 7, the metal wire extends reciprocally for 12 times under strain, and then melts to be connected with the transparent film 60. As shown in Fig. 8, a first cell 31A and a second cell 31B are prepared. As shown in Fig. 9, a front surface of the first cell 31A is connected with a metal wire, and a back surface of the second cell 31B is connected with the metal wire, so as to form a cell array 30. Fig. 9 shows two cells 31. As above, when the cell array 30 has a plurality of cells 31, the metal wire extends reciprocally to connect the front surface of the first cell 31 and the back surface of the second cell 31 adjacent to the first cell 31, i.e. connecting secondary grid lines of the first cell 31 with back electrodes of the second cell 31 by the metal wire. The metal wire extends reciprocally under strain from two clips at two ends thereof.

In the embodiment shown in Fig. 9, the adjacent cells are connected in series. As above, the adjacent cells can be connected in parallel by the metal wire in the light of practical requirements.

The cell array 30 obtained is superposed with the upper cover plate 10, the front adhesive layer 20, the back adhesive layer 40 and the back plate 50 in sequence, in which the front surface of the cell 31 faces the transparent film 60； the conductive wires 32 on the transparent film 60 are in contact with the secondary grid lines 312 on the cell 31； and the back surface of the cell 31 faces the back adhesive layer 40. Then they are laminated to obtain the solar cell module 100.

In the following, the solar cell module 100 of the present disclosure will be described with respect to specific examples.

Example 1

Example 1 is used to illustrate the solar cell module 100 according to the present disclosure and the manufacturing method thereof.

(1) Manufacturing a metal wire S

A copper wire is coated with a Sn40％-Bi55％-Pb5％alloy layer, in which the copper wire has a cross section of 0.04mm², and the conductive adhesive has a thickness of 16μm, so as to obtain the metal wire S.

The metal wire extends reciprocally under strain from two clips at two ends of the copper wire, so as to form 15 parallel conductive wires. The distance between parallel adjacent conductive wires is 9.9mm.

Then part of the conductive wires are arranged in the surface of the transparent film made of a PET film； then the conductive wires are heated, such that the contact portion of the transparent film and the conductive wires is softened or melted, so as to melt and fix the conductive wires and the transparent film together, and the metal wire comes out from the transparent film.

(2) Manufacturing a solar cell module 100

A POE adhesive layer in 1630×980×0.5mm is provided (melting point: 65℃) , and a glass plate in 1633×985×3mm and a polycrystalline silicon cell 31 in 156×156×0.21mm are provided correspondingly. The cell 31 has 91 secondary grid lines (silver, 60μm in width, 9μm in thickness) , each of which substantially runs through the cell 31 in a longitudinal direction, and the distance between the adjacent secondary grid lines is 1.7mm. The cell 31 has five back electrodes (tin, 1.5mm in width, 10μm in thickness) on its back surface. Each back electrode substantially runs through the cell 31 in a longitudinal direction, and the distance between the adjacent back electrodes is 31mm.

60 cells are arranged in a matrix form (six rows and ten columns) . In two adjacent cells in the same row, the transparent film connected with the conductive wires by melting is disposed on a front surface of a first cell, and the secondary grid lines contact with the conductive wires. The other conductive wires which are welded extend onto a back surface of a second cell to be connected with the back electrodes on the back surface of the second cell.

Then, an upper glass plate, an upper POE adhesive layer, multiple cells arranged in a matrix form and welded with the metal wire, a lower POE adhesive layer and a lower glass plate are superposed sequentially from up to down, in which the shiny surface of the cell faces the front adhesive layer 20, and the shady surface of the cell faces the back adhesive layer 40, and finally they are laminated in a laminator so as to obtain the solar cell module A1.

Comparison example 1

The difference of Comparison example 1 and Example 1 lies in that the cells 31 are arranged in a matrix form. 15 metal wires connected in series are stuck on the transparent adhesive film, and then stuck on the solar cell. In two adjacent cells, the metal wire connects a front surface of a first cell and a back surface of a second cell. Then, an upper glass plate, an upper POE adhesive layer, the transparent adhesive film, multiple cells arranged in a matrix form and welded with the metal wire, the transparent adhesive film, a lower POE adhesive layer and a lower glass plate are superposed sequentially from up to down. In such a way, a solar cell module D1 is obtained.

Example 2

Example 2 is used to illustrate the solar cell module 100 according to the present disclosure and the manufacturing method thereof.

(1) Manufacturing a metal wire S

A copper wire is coated with an epoxy resin, in which the copper wire has a cross section of 0.04mm², and the conductive adhesive has a thickness of 16μm, so as to obtain the metal wire S.

The metal wire extends reciprocally under strain from two clips at two ends of the copper wire, so as to form 20 parallel conductive wires. The distance between parallel adjacent conductive wires is 9.9mm.

(2) Manufacturing a solar cell module 100

Then, an upper glass plate, an upper POE adhesive layer, multiple cells arranged in a matrix form and welded with the metal wire, a lower POE adhesive layer and a lower glass plate are superposed sequentially from up to down, in which the shiny surface of the cell faces the front adhesive layer 20, and the shady surface of the cell faces the back adhesive layer 40, and finally they are laminated in a laminator so as to obtain the solar cell module A2.

Example 3

The solar cell module is manufactured according to the method in Example 1, but the difference compared with Example 1 lies in that a short grid line 33 (silver, 0.1mm in width) is disposed on the secondary grid line of the shiny surface of the cell 31, and is perpendicular to the secondary grid line for connecting part of the secondary grid line at the edge of the shiny surface of the cell with the conductive wire, as shown in Fig. 12, so as to obtain a solar cell module A3.

Example 4

The solar cell module is manufactured according to the method in Example 1, but the difference compared with Example 1 lies in that the cells of six columns and six rows are connected in such a manner that in two adjacent rows of cells, the conductive wires extends from a shiny surface of a cell at an end of the a^th row (a≥1) to form electrical connection with a back surface of a cell at an adjacent end of the (a+1) ^th row, so as to connect the two adjacent rows of cells. The conductive wires for connecting the two adjacent rows of cells are arranged in perpendicular to the conductive wires for connecting the adjacent cells in the two rows. In such a way, the solar cell module A4 is obtained.

Testing example 1

(1) Whether the metal wire in the solar cell module drifts is observed with the naked eyes；

(2) According to the method disclosed in IEC904-1, the solar cell modules manufactured in the above examples and the comparison example are tested with a single flash simulator under standard test conditions (STC) : 1000W/m² of light intensity, AM1.5 spectrum, and 25℃. The photoelectric conversion efficiency of each cell is recorded. The testing result is shown in Table 1.

Table 1

The fill factor refers to a ratio of the power at the maximum power point of the solar cell module and the maximum power theoretically at zero resistance, and represents the proximity of the actual power with respect to the theoretic maximum power, in which the greater the value is, the higher the photoelectric conversion efficiency is. Generally, the series resistance is small, so the fill factor is great. The photoelectric conversion efficiency refers to a ratio of converting the optical energy into electric energy by the module under a standard lighting condition (1000W/m² of light intensity) . The series resistance is equivalent to the internal resistance of the solar module, in which the greater the value is, the poorer the performance of the module is. The fill factor represents a ratio of the actual maximum power and the theoretical maximum power of the module, in which the greater the value is, the better the performance of the module is. The open-circuit voltage refers to the voltage of the module in an open circuit under a standard lighting condition. The short-circuit current refers to the current of the module in a short circuit under a standard lighting condition. The working voltage is the output voltage of the module working with the largest power under a standard lighting condition. The working current is the output current of the module working with the largest power under a standard lighting condition. The power is the maximum power which the module can reach under a standard lighting condition.

It can be indicated from Table 1 that for the solar cell module according to the embodiments of the present disclosure, the metal wire will not drift, and higher photoelectric conversion efficiency can be obtained.

In the specification, it is to be understood that terms such as “central, ” “longitudinal, ” “lateral, ” “length, ” “width, ” “thickness, ” “upper, ” “lower, ” “front, ” “rear, ” “left, ” “right, ” “vertical, ” “horizontal, ” “top, ” “bottom, ” “inner, ” “outer, ” “clockwise, ” and “counterclockwise” should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the present disclosure be constructed or operated in a particular orientation.

In addition, terms such as “first” and “second” are used herein for purposes of description and are not intended to indicate or imply relative importance or significance or to imply the number of indicated technical features. Thus, the feature defined with “first” and “second” may comprise one or more of this feature. In the description of the present disclosure, “aplurality of” means two or more than two, unless specified otherwise.

In the present disclosure, unless specified or limited otherwise, a structure in which a first feature is “on” or “below” a second feature may include an embodiment in which the first feature is in direct contact with the second feature, and may also include an embodiment in which the first feature and the second feature are not in direct contact with each other, but are contacted via an additional feature formed therebetween. Furthermore, a first feature “on, ” “above, ” or “on top of” a second feature may include an embodiment in which the first feature is right or obliquely “on, ” “above, ” or “on top of” the second feature, or just means that the first feature is at a height higher than that of the second feature； while a first feature “below, ” “under, ” or “on bottom of” a second feature may include an embodiment in which the first feature is right or obliquely “below, ” “under, ” or “on bottom of” the second feature, or just means that the first feature is at a height lower than that of the second feature.

Reference throughout this specification to “an embodiment, ” “some embodiments, ” or “some examples” means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, these terms throughout this specification do not necessarily refer to the same embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

Although embodiments of the present disclosure have been shown and described, it would be appreciated by those skilled in the art that changes, modifications, alternatives and variations can be made in the embodiments without departing from the scope of the present disclosure.

Claims

A solar cell module, comprising an upper cover plate, a front adhesive layer, a cell, a back adhesive layer and a back plate superposed in sequence, a secondary grid line being disposed on a front surface of the cell, a transparent film being disposed between the front adhesive layer and the cell, a conductive wire being disposed on a surface of the transparent film corresponding to the cell, the conductive wire being inserted into the transparent film and exposed therefrom, and being formed of a metal wire and connected with the secondary grid line, the transparent film having a melting point higher than the melting point of the front adhesive layer and the back adhesive layer, the metal wire including a metal wire body and a connection material layer coating the metal wire body, and the conductive wire being connected with the secondary grid line by the connection material layer.
The solar cell module according to claim 1, wherein the transparent film is made of a transparent material with a melting point higher than 160℃.
The solar cell module according to claim 2, wherein the transparent film is formed with at least one of polyethylene glycol terephthalate, polybutylene terephthalate and polyimide.
The solar cell module according to any one of claims 1 to 3, wherein the transparent film has a thickness of 50 to 200μm, and a light transmittance of no less than 90％.
The solar cell module according to any one of claims 1 to 4, wherein the connection material layer is a conductive adhesive layer.
The solar cell module according to any one of claims 1 to 4, wherein the connection material layer is a conductive adhesive or an alloy layer.
The solar cell module according to claim 6, wherein the alloy contains Sn, Bi, and at least one of In, Ag, Sb, Pb and Zn.
The solar cell module according to claim 7, wherein based on the total weight of the alloy, there are 15 to 60 weight percent of Bi, 30 to 75 weight percent of Sn, 0 to 20 weight percent of Cu, 0 to 40 weight percent of In, 0 to 3 weight percent of Ag, 0 to 20 weight percent of Sb, 0 to 10 weight percent of Pb, and 0 to 20 weight percent of Zn.
The solar cell module according to claim 8, wherein the alloy is at least one selected from 50％Sn-48％Bi-1.5％Ag-0.5％Cu, 58％Bi-42％Sn, and 65％Sn-20％Bi-10％Pb-5％Zn.
The solar cell module according to any one of claims 1 to 9, wherein the connection material layer has a thickness of 1 to 100μm, and the metal wire has a cross section of 0.01 to 0.5mm².
The solar cell module according to claim 1, wherein a ratio of a thickness of the connection material layer and a diameter of the metal wire is (0.02-0.5) : 1.
The solar cell module according to any one of claims 1 to 11, wherein there are multiple cells to constitute a cell array, adjacent cells connected by the metal wire that extends reciprocally between a surface of a first cell of the adjacent cells and a surface of a second cell thereof.
The solar cell module according to claim 12, wherein the metal wire extends reciprocally between a front surface of the first cell and a back surface of the second cell.
The solar cell module according to claim 13, wherein part of the conductive wire connected with the secondary grid line of a first cell constitute a front conductive wire of the first cell； the connection material layer is arranged in a position where the metal wire body of the front conductive wire and the secondary grid line are connected, or coats the metal wire body along an entire length of the metal wire body constituting the front conductive wire.
The solar cell module according to claim 13, wherein a transparent film is disposed between the back adhesive layer and the second cell； the transparent film is provided with the conductive wires on its surface opposite the second cell； the conductive wires are inserted in the transparent film and come therefrom； the conductive wires are connected with the back electrode of the second cell by a connection material layer.
The solar cell module according to claim 15, wherein part of the conductive wire connected with the back electrode of a second cell constitute a back conductive wire of the second cell； the connection material layer is arranged in a position where the metal wire body of the back conductive wire and the back electrode are connected, or coats the metal wire body along an entire length of the metal wire body constituting the back conductive wire.
The solar cell module according to claim 16, wherein the conductive wire is formed by reciprocally winding a metal wire.
The solar cell module according to any one of claims 12 to 17, wherein the metal wire extends reciprocally for 10 to 60 times.
The solar cell module according to any one of claims 12 to 18, wherein a distance between two adjacent segments of the metal wire ranges from 2.5mm to 15mm.
The solar cell module according to any one of claims 12 to 19, wherein the two adjacent segments of the metal wire form a U-shape structure or a V-shape structure.
The solar cell module according to any one of claims 1 to 20, wherein a short grid line is disposed along an edge of the front surface of the cell, and the short line connects a secondary grid line close to the edge of the cell with the conductive wire.
The solar cell module according to claim 21, wherein the short grid line is perpendicular to the secondary grid line.
The solar cell module according to any one of claims 1 to 22, wherein the cells are arranged in an n×m matrix form, n representing a column, and m representing a row；

in a row of cells, the metal wire extends reciprocally between a surface of a first cell and a surface of a second cell adjacent to the first cell； in two adjacent rows of cells, the metal wire extends reciprocally between a surface of a cell in a a^th row and a surface of a cell in a (a+1) ^th row, and m-1≥a≥1.
The solar cell module according to claim 23, wherein in two adjacent rows of cells, the metal wire extends reciprocally between a surface of a cell at an end of the a^th row and a surface of a cell at an end of the (a+1) ^th row, the end of the a^th row and the end of the (a+1) ^th row located at the same side of the matrix form.
The solar cell module according to claim 24, wherein in a row of cells, the metal wire extends reciprocally between a front surface of the first cell and a back surface of the second cell adjacent to the first cell；

in two adjacent rows of cells, the metal wire extends reciprocally between a front surface of a cell at the end of the a^th row and a back surface of a cell at the end of the (a+1) ^th row, to connect the two adjacent rows of cells in series.
The solar cell module according to any one of claims 23 to 25, wherein there is a metal wire extending reciprocally between adjacent cells in a row； and there is a metal wire extending reciprocally between cells in adjacent rows.
The solar cell module according to any one of claims 1 to 26, wherein the secondary grid line has a width of 40 to 80μm and a thickness of 5 to 20μm； there are 50 to 120 secondary grid lines, a distance between adjacent secondary grid lines ranging from 0.5 to 3mm.
A method for manufacturing a solar cell module, comprising:

welding a conductive wire constituted by a metal wire into a transparent film, in which the metal wire comes out from the transparent film, and includes a metal wire body and a connection material layer applied to the metal wire body；

superposing an upper cover plate, a front adhesive layer, the transparent film, the cell, a back adhesive layer and a back plate in sequence, and laminating them to obtain the solar cell module, in which the conductive wire and a secondary grid line of the cell are connected by the connection material layer； the transparent film has a melting point higher than the melting point of the front adhesive layer and the back adhesive layer.
The method according to claim 28, wherein the metal wire is welded into the transparent film before they are superposed.
The method according to claim 28, wherein the conductive wire and the secondary grid line are connected before or after they are superposed, or when they are laminated.
The method according to any one of claims 28 to 30, wherein the connection material layer is a conductive adhesive or an alloy layer.
The method according to claim 28, wherein the alloy layer contains Sn, and at least one of Bi, Cu, In, Ag, Sb, Pb and Zn.
The method according to any one of claims 28 to 32, wherein the connection material layer has a thickness of 1 to 100μm, and the metal wire has a cross section of 0.01 to 0.5mm².
The method according to any one of claims 28 to 33, wherein the metal wire extends reciprocally between a surface of a first cell and a surface of a second cell adjacent to the first cell.
The method according to claim 34, wherein the metal wire extends reciprocally between a front surface of the first cell and a back surface of the second cell.
The method according to claim 34 or 35, wherein the conductive wire is formed by reciprocally winding a metal wire.
The method according to any one of claims 34 to 36, wherein the metal wire extends reciprocally for 10 to 60 times.
The method according to claim 37, wherein two adjacent segments of the metal wire form a U-shape structure or a V-shape structure.
The method according to any one of claims 28 to 38, wherein the metal wire is welded into the transparent film before they are superposed.
The method according to any one of claims 28 to 39, wherein the transparent film is made of a transparent material with a melting point higher than 160℃.
The method according to claim 40, wherein the transparent film is formed with at least one of polyethylene glycol terephthalate, polybutylene terephthalate and polyimide.
The method according to any one of claims 28 to 41, wherein the transparent film has a thickness of 50 to 200μm, and a light transmittance of no less than 90％.