WO2023005913A1

WO2023005913A1 - Solar cell string and manufacturing method therefor and application thereof

Info

Publication number: WO2023005913A1
Application number: PCT/CN2022/107881
Authority: WO
Inventors: 刘宗涛; 陈达明; 陈奕峰; 项建军; 刘志远; 邹杨; 刘成法; 王尧; 夏锐
Original assignee: 天合光能股份有限公司
Priority date: 2021-07-28
Filing date: 2022-07-26
Publication date: 2023-02-02
Also published as: CN113851550A

Abstract

The present invention provides a solar cell string and a manufacturing method therefor and an application thereof. The solar cell string comprises solar cells and a welding strip connected in series to the solar cells; the welding strip is bonded to the surfaces of the solar cells by means of a double-sided transparent adhesive tape; the double-sided transparent adhesive tape is located between the welding strip and the solar cells; and short grid lines in directions different from auxiliary grid lines are provided at the positions of the solar cells where the double-sided transparent adhesive tapes are placed on. According to the manufacturing method for the solar cell string provided by the present invention, the welding strip can be easily bonded to the solar cells, an original welded pad point is replaced, the shading loss is reduced while reducing the use amount of silver paste, and the solar cell string can be obtained by changing some accessories on a current welding machine; the transmittance of the adhesive tape is larger than 50%, sunlight is not affected to enter the area below the adhesive tape, short transverse lines are used for leading out photo-generated current generated in the area below the adhesive tape to be close to the grid lines, and the adhesive tape does not need to be combined with a welding strip firstly, such that the manufacturing process is greatly simplified.

Description

Solar battery string and its preparation method and application

technical field

The invention belongs to the technical field of solar cells, and relates to a solar cell string and its preparation method and application, in particular to a busbar-free solar cell string and its preparation method and application.

Background technique

In the field of busbar-free solar cells, using thin grid lines for current collection will encounter problems such as increased series resistance and decreased fill factor, resulting in a serious reduction in the power of the manufactured modules; Reduce the series resistance, but the cost will rise sharply due to the increase of the amount of silver used. At the same time, the wide gate line will also cause the insulation effect between P-N to deteriorate and the problem of easy leakage.

In the solar cell industry, several monolithic silicon cells need to be connected together in series with ribbons, so as to draw out the current generated by all the silicon cells. The connection method of the ribbon is that one end is welded to the front busbar of the front side silicon cell, and the other end is welded to the back busbar of the rear side silicon cell. The current thickness of silicon cells tends to be thinner, and it is more likely to produce hidden cracks when they are connected by solder ribbons. In this way, the connection method of the ribbon will be more and more limited.

When the solar cells are connected in series with strip-shaped ribbons to form a battery string, since the ribbons are in direct contact with EVA outside the area of the adhesive tape (or called a tape-shaped film), when laminating, EVA ((Ethylene Vinyl Acetate Copolymer)) has fluidity in melting, and EVA insulation tape and fine grid may appear during lamination.

The best way to improve the application of screen printed busbars is to avoid busbars altogether. However, the technical difficulty of completely avoiding busbars lies in how to connect the batteries in series. At present, there is also a polymer adhesive film provided by the existing technology. The adhesive film is first bonded to the wire, then placed on the battery, and finally laminated. together. This technology can completely avoid the use of busbars, but the adhesive film needs a special structure, and it needs to be bonded with the wires, and then fixed with the battery, which increases the complexity of the process.

CN100431175A discloses a kind of electrode, and this electrode comprises flat surface transparent electrical insulation optical film, and adhesive is coated on flat surface, then parallel wire is embedded in adhesive layer, and adhesive thickness is less than wire thickness, thereby makes protruding part Form ohmic contact with the optoelectronic element.

CN108419433A discloses a polymer conductor plate, a solar cell and a production method thereof. In a homogeneous polymer plate, a two-layer or three-layer region is formed through heat, radiation, chemical and other means, wherein the first region has a low AC The degree of linking or polymerization is heat-adhesive, the second area has a high degree of cross-linking or polymerization, and is a support layer, and the third layer has a lower degree of cross-linking or polymerization, and adheres to the first area. Groups of parallel wires form polymer plates, which in turn form battery strings.

Both of the above two documents mentioned the curing of transparent film or polymer board or liquid glue. As a technical person in this field, these three names all refer to the polymer film, which is bonded to the wire and then laminated. However, these three methods must add additional processing platforms for polymer film materials, bonding platforms for film materials and wires, etc., which undoubtedly increase the cost and complexity. In addition, the adhesive film provided by these three methods, that is, the adhesive layer, is on the layer where the metal wire is away from the solar cell, and is fully covered, so its light transmittance and stability have high requirements.

Therefore, how to adjust the connection mode of the soldering strips while avoiding shading of the busbar of the solar cell and large consumption of silver is a technical problem to be solved urgently.

Contents of the invention

The object of the present invention is to provide a solar cell string and its preparation method and application. The invention uses double-sided transparent tape to connect the solder ribbon to the solar cell, and with a special grid design, the solder ribbon can be easily bonded to the solar cell, replacing the original welding pad points (metal solder joints) ), forming a solar cell string, reducing the amount of silver paste and reducing shading loss, and can be obtained by changing some accessories on the current welding machine. There is no need to combine the tape with the welding strip first, which greatly simplifies the preparation process.

To achieve this purpose of the invention, the present invention adopts the following technical solutions:

In a first aspect, the present invention provides a solar cell string, the solar cell string includes solar cells and a ribbon connecting the solar cells in series, and the solder ribbon is bonded to the solar cell by double-sided scotch tape The surface of the double-sided scotch tape is located between the solder ribbon and the solar cells, and the position where the double-sided scotch tape is placed in the solar cell is provided with a short grid line in a direction different from that of the auxiliary grid line.

The solar battery string provided by the present invention refers to a string of component structures formed by connecting multiple groups of battery pieces in series through soldering strips, connected end to end. The connection method is that the positive pole of the previous battery piece is connected with the negative pole of the next battery piece That is, the positive and negative electrodes are connected alternately. The provided welding strip is the wire connecting the cells. The welding strip is segmented and its length is greater than or equal to twice the length of the solar cell. It is in close contact with the front of a solar cell, one side is in contact with the back of an adjacent solar cell, and connected in sequence to form a solar cell string.

In the present invention, the strip-shaped tape cannot affect the light absorption of the battery, so it must have a transparent characteristic, and at the same time, there is no specific requirement for the conductivity of the tape, and it can be a conductive tape or a non-conductive tape.

In a solar cell, the grid wire is the electrode, and its function is to lead out the current generated by the solar cell. Generally, the grid wire (electrode) of the solar cell is formed by screen printing and then sintered, and has many single wires parallel to each other with the same spacing composition. The battery string provided by the present invention is a battery string without a main grid, that is, there are only auxiliary grid lines and no main grid lines.

In the present invention, when the double-sided scotch tape is positioned between the solar cell sheet and the soldering tape, the grid lines at the bottom of the soldering tape will insulate between the grid lines and the soldering tape (wires) due to the insertion of the intermediate tape, resulting in The current generated in the area cannot be exported, and by matching special short grid lines, the design of multiple single grid lines parallel to each other is broken. Even if there is tape, the design of short grid lines in different directions from the auxiliary grid lines can also The current is exported to the adjacent sub-gate lines, so as to be transmitted to the soldering strips (wires), avoiding insulation.

The double-sided transparent adhesive tape provided by the present invention may be located in the area of the short grid lines, and there is no special limitation on the position of the adhesive tape, as long as the solder tape and the solar cells can be closely bonded together.

The invention uses double-sided transparent tape to connect the solder ribbon to the solar cell, and with a special grid design, the solder ribbon can be easily bonded to the solar cell, replacing the original welding pad points (metal solder joints) ), form a solar cell string, reduce the amount of silver paste and reduce the shading loss, and can be obtained by changing some accessories on the current welding machine, the method is simple and convenient; the tape is located between the welding tape and the battery, and will not affect the photogenerated current of the solar cell under the tape There is no need to combine the tape with the welding strip first, which greatly simplifies the preparation process.

Preferably, the transmittance of the double-sided scotch tape is >50%, such as 51%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96% , 97%, 98% or 99%, etc.

The transmittance of the double-sided scotch tape provided by the present invention is the transmittance after lamination when the solar battery string is applied to a photovoltaic module.

In the present invention, if the transmittance of the double-sided transparent tape is too low, it will cause light-shielding loss and affect the power generation efficiency.

Preferably, the double-sided transparent tape is arranged along a direction perpendicular to a direction parallel to the welding strips. Preferably, the direction of the short gate lines is perpendicular to the parallel direction of the auxiliary gate lines.

Preferably, the double-sided transparent tape has a width of 0.1-30mm, such as 0.1mm, 1mm, 5mm, 10mm, 15mm, 20mm, 25mm or 30mm.

Preferably, the number of double-sided transparent tapes is ≥ 2, such as 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 20 etc.

The number of double-sided scotch tapes pointed out in the present invention refers to the number of adhesive tapes in each solar cell string in the solar cell string, and the number of adhesive tapes can also be understood as the number of rows or columns of adhesive tape on the solar cell sheet. The number of strips of the adhesive tape matches the width of the adhesive tape, and the width is relatively narrow, which can be set more adaptably.

Preferably, the number of the welding ribbons is ≥ 1, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20 , 25, 30 or 35 etc. Preferably, the welding strip includes a wire and a coating covering the surface of the wire.

In the present invention, in order not to increase the series resistance, the number of wires is negatively correlated with the size, and the thinner the wires, the more wires are required.

Preferably, the diameter of the wire is 0.1-400 μm, such as 0.1 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm , 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, or 400 μm, etc., preferably 100 to 300 μm.

Preferably, the coating comprises a single metal coating and/or an alloy coating.

In the present invention, the coating in the ribbon plays the role of welding with the grid wire of the solar cell, so different wrapping layers correspond to different welding temperatures, thereby affecting the lamination temperature.

Preferably, the alloy coating has a melting point of 50°C to 200°C, such as 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, etc., preferably 100 to 160°C.

In the present invention, the alloy coating with a melting point of 120-160°C is selected to adapt to the lamination temperature during the subsequent preparation of photovoltaic modules. During the lamination process, when the melting point temperature of the alloy coating is lower than the lamination temperature, the alloy coating The coating will melt, flow down along the wire, and gather at the grid line of the solar cell, realizing the cooling welding. The main part of the wire can be copper wire or other wires with good electrical conductivity, preferably copper wire.

Preferably, the length of the short grid lines is greater than the width of the double-sided transparent tape.

In the present invention, it is ensured that the length of the short grid lines is greater than the width of the double-sided transparent tape, so that the tape insulation between the welding strip and the auxiliary grid lines perpendicular to the welding strip will not occur.

Preferably, the material of the short grid lines is consistent with that of the auxiliary grid lines. Preferably, the sticking area of the double-sided transparent tape is smaller than the area of the short grid lines.

In a second aspect, the present invention provides a method for preparing the solar cell string according to the first aspect, the preparation method comprising:

Set a short grid line perpendicular to the parallel direction of the auxiliary grid line at the position where the double-sided transparent tape is placed on the solar cell sheet, then paste the double-sided transparent tape on the surface of the solar cell sheet along the parallel direction of the auxiliary grid line, and place the soldering tape on the double-sided grid line. The surface of the scotch tape is used to connect the solar cells in series with a soldering tape to obtain the solar cell string.

Preferably, after the welding ribbon is placed on the surface of the double-sided scotch tape, pressure is applied to the welding ribbon. In the third aspect, the present invention also provides a photovoltaic module, the photovoltaic module comprising the first glass, the first adhesive film, the solar cell string as described in the first aspect, the second adhesive film and the second glass which are sequentially stacked .

Preferably, a third adhesive film is provided between the first adhesive film and the solar battery string as described in the first aspect.

Preferably, a fourth adhesive film is arranged between the solar battery string as described in the first aspect and the second adhesive film.

In the present invention, on the basis of the original adhesive film, a new adhesive film is further added to cover. The purpose of covering is to avoid direct contact between the battery and the first and second adhesive films. It prevents the first and second adhesive films from filling the gap, and also improves the electrical contact because the first and second adhesive films are more fluid at the lamination temperature. The situation that the first and second adhesive films insulate the welding strip and the grid line during the lamination process is avoided.

Preferably, the thicknesses of the third adhesive film and the fourth adhesive film are each independently 0.1-100 μm, such as 0.1 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100μm etc.

Compared with the prior art, the present invention has the following beneficial effects:

Description of drawings

Fig. 1 is a schematic structural diagram of a single solar cell in a solar cell string provided in a specific embodiment.

Fig. 2 is a partial schematic diagram of a side view of a solar cell string provided in a specific embodiment.

Fig. 3 is a schematic structural diagram of a solar cell string provided in a specific embodiment.

1-solar battery sheet, 2-welding ribbon, 3-double-sided scotch tape, 4-short grid wire.

Detailed ways

In order to describe the embodiments of the present invention in detail below, the same or similar reference numerals represent the same or similar components or components having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

In the description of the present invention, unless otherwise clearly stipulated and limited, the terms "connected", "connected" and "installed" should be understood in a broad sense, for example, it can be an installation connection, a detachable connection, or a mechanical connection. A connection can also be an electrical connection, a direct connection, or an indirect connection through an intermediary, or an internal connection between two elements or an interaction relationship between two elements. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the description of the present invention, unless otherwise clearly specified and limited, a first feature being "on" or "under" a second feature may include direct contact between the first feature and the second feature, or include the first feature Not in direct contact with the second feature but through another feature therebetween. Moreover, "above", "above" and "above" the first feature on the second feature include that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. "Below", "beneath" and "under" the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.

The technical solutions of the present invention will be further described below through specific embodiments. It should be clear to those skilled in the art that the embodiments are only for helping to understand the present invention, and should not be regarded as specific limitations on the present invention.

In a specific embodiment, the present invention provides a solar battery string (as shown in FIG. 3 ) and a preparation method thereof. As shown in FIG. Ribbon 2 is bonded to the surface of the solar cell 1 (as shown in Figure 2) by double-sided scotch tape 3. The double-sided scotch tape 3 is located between the solder ribbon 2 and the solar cell 1, and the solar cell 1, where the double-sided transparent tape 3 is placed, there are short grid lines 4 in a direction different from that of the auxiliary grid lines. Furthermore, the direction of the short grid lines 4 is perpendicular to the direction parallel to the auxiliary grid lines.

The transmittance of the double-sided transparent tape 3 is >50%; the double-sided transparent tape 3 is arranged along the vertical direction parallel to the welding ribbon 2, and the width of the double-sided transparent tape 3 is 0.1-30 mm; the number of double-sided transparent tape 3 is ≥ 2 pieces.

The number of welding strips 2 is ≥ 1; the welding strips 2 include a wire and a coating covering the surface of the wire; the diameter of the wire is 0.1-400 μm, and further 100-300 μm; the coating includes a single metal coating and/or alloy Coating; the melting point of the alloy coating is 50-200°C, further 100-160°C.

The length of the short grid lines 4 is greater than the width of the double-sided transparent tape 3; the material of the short grid lines 4 is consistent with the material of the auxiliary grid lines;

Preparation methods include:

Place the double-sided scotch tape 3 on the solar battery sheet 1 to arrange short grid lines 4 perpendicular to the parallel direction of the auxiliary grid lines, and then paste the double-sided scotch tape 3 on the surface of the solar cell sheet 1 along the parallel direction of the auxiliary grid lines. The soldering tape 2 is placed on the surface of the double-sided transparent tape 3, pressure is applied to the soldering tape 2, and the solar cells 1 are connected in series by the soldering tape 2 to obtain the solar cell string.

In another specific embodiment, the present invention provides a photovoltaic module, which includes a first glass, a first adhesive film, a solar cell string as provided in the above specific embodiment, and a second adhesive film that are sequentially stacked. and second glass.

A third adhesive film is arranged between the first adhesive film and the solar cell string provided in the above specific embodiment;

A fourth adhesive film is provided between the solar cell string and the second adhesive film as provided in the above specific embodiment;

The thicknesses of the third adhesive film and the fourth adhesive film are each independently 0.1-100 μm.

Example 1

This embodiment provides a solar cell string and its preparation method, based on the solar cell string and its preparation method provided in the specific implementation:

Among them, the transmittance of the double-sided transparent tape 3 is 88%; the width of the double-sided transparent tape 3 is 3 mm; the number of double-sided transparent tape 3 is 10.

The number of welding strips 2 is 18; the welding strip 2 includes a wire and a coating covering the surface of the wire; the diameter of the wire is 260 μm; the coating is an alloy coating; the melting point of the alloy coating is 120 ° C; short grid wire 4 has a length of 5 mm.

This embodiment also provides a photovoltaic module based on the photovoltaic module provided in the detailed description: wherein, the thickness of the third adhesive film and the fourth adhesive film is 50 μm.

Example 2

Among them, the transmittance of the double-sided transparent tape 3 is 90%; the width of the double-sided transparent tape 3 is 4 mm; the number of double-sided transparent tape 3 is 8.

The number of welding strips 2 is 20; the welding strip 2 includes a wire and a coating covering the surface of the wire; the diameter of the wire is 240 μm; the coating is an alloy coating; the melting point of the alloy coating is 125 ° C; short grid wire 4 has a length of 8 mm.

This embodiment also provides a photovoltaic module based on the photovoltaic module provided in the specific implementation manner: wherein, the thickness of the third adhesive film and the fourth adhesive film is 80 μm.

Example 3

Among them, the transmittance of the double-sided transparent tape 3 is 91%; the width of the double-sided transparent tape 3 is 5 mm; the number of double-sided transparent tape 3 is 6.

The number of welding strips 2 is 24; the welding strip 2 includes a wire and a coating covering the surface of the wire; the diameter of the wire is 180 μm; the coating is an alloy coating; the melting point of the alloy coating is 130 ° C, and the short grid wire 4 has a length of 7 mm.

This embodiment also provides a photovoltaic module based on the photovoltaic module provided in the detailed description: wherein, the thickness of the third adhesive film and the fourth adhesive film is 10 μm.

Example 4

Among them, the transmittance of the double-sided transparent tape 3 is 92%; the width of the double-sided transparent tape 3 is 7mm; and the number of double-sided transparent tape 3 is 5.

The number of welding strips 2 is 30; the welding strip 2 includes a wire and a coating covering the surface of the wire; the diameter of the wire is 140 μm; the coating is an alloy coating; the melting point of the alloy coating is 140 ° C; short grid wire 4 has a length of 9mm.

This embodiment also provides a photovoltaic module based on the photovoltaic module provided in the detailed description: wherein, the thickness of the third adhesive film and the fourth adhesive film is 20 μm.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and those skilled in the art should understand that any person skilled in the art should be aware of any disclosure in the present invention Within the technical scope, easily conceivable changes or substitutions all fall within the scope of protection and disclosure of the present invention.

Claims

A solar cell string, characterized in that the solar cell string includes solar cell sheets and soldering strips connected in series to the solar cell sheets, and the soldering tape is bonded to the surface of the solar cell sheet by a double-sided scotch tape, The double-sided transparent tape is located between the soldering strip and the solar battery sheet, and the position where the double-sided transparent tape is placed in the solar battery sheet is provided with a short grid line in a direction different from that of the auxiliary grid line.
The solar cell string according to claim 1, wherein the transmittance of the double-sided transparent tape is >50%.
The solar cell string according to claim 2, wherein the double-sided transparent adhesive tape is arranged along a direction perpendicular to a direction parallel to the soldering strips.
The solar cell string according to claim 3, wherein the direction of the short grid lines is perpendicular to the parallel direction of the auxiliary grid lines.
The solar cell string according to claim 1 or 2, characterized in that the width of the double-sided transparent tape is 0.1-30 mm.
The solar cell string according to claim 1, wherein the number of double-sided transparent tapes is ≥ 2.
The solar battery string according to claim 1, characterized in that the number of the welding ribbons is ≥ 1.
The solar cell string according to claim 7, characterized in that, the soldering strips include a wire and a coating covering the surface of the wire, the diameter of the wire is 0.1-400 μm, and the coating includes a single metal coating And/or alloy coating, the melting point of the alloy coating is 50-200°C.
The solar battery string according to claim 8, wherein the diameter of the wire is 100-300 μm; the melting point of the alloy coating is 100-160° C.
The solar cell string according to claim 1, wherein the length of the short grid lines is greater than the width of the double-sided transparent tape.
The solar cell string according to claim 10, wherein the material of the short grid lines is consistent with that of the auxiliary grid lines.
The solar cell string according to claim 10, characterized in that, the sticking area of the double-sided transparent tape is smaller than the area of the short grid lines.
The method for preparing a solar cell string according to any one of claims 1-12, wherein the method comprises:

Set a short grid line perpendicular to the parallel direction of the auxiliary grid line at the position where the double-sided transparent tape is placed on the solar cell sheet, then paste the double-sided transparent tape on the surface of the solar cell sheet along the parallel direction of the auxiliary grid line, and place the soldering tape on the double-sided grid line. The surface of the scotch tape is used to connect the solar cells in series with a soldering tape to obtain the solar cell string.
The method for preparing a solar cell string according to claim 13, characterized in that, after placing the soldering tape on the surface of the double-sided transparent tape, pressure is applied to the soldering tape.
A photovoltaic module, characterized in that the photovoltaic module comprises first glass, a first adhesive film, a solar cell string according to any one of claims 1-12, a second adhesive film and a second adhesive film which are sequentially stacked. Glass.
The photovoltaic module according to claim 15, wherein a third adhesive film is arranged between the first adhesive film and the solar cell string according to any one of claims 1-12;

A fourth adhesive film is arranged between the solar battery string as claimed in any one of claims 1-12 and the second adhesive film.
The photovoltaic module according to claim 16, wherein the thicknesses of the third adhesive film and the fourth adhesive film are each independently 0.1-100 μm.