WO2024055674A1

WO2024055674A1 - Soldering method and photovoltaic module

Info

Publication number: WO2024055674A1
Application number: PCT/CN2023/102335
Authority: WO
Inventors: 赵德宝; 陈鹏; 陈军; 李华
Original assignee: 泰州隆基乐叶光伏科技有限公司
Priority date: 2022-09-14
Filing date: 2023-06-26
Publication date: 2024-03-21
Also published as: CN115632086A

Abstract

The present application relates to the technical field of solar photovoltaics. Provided are a soldering method and a photovoltaic module. The method is used for soldering interdigitated back contact solar cells. Each solar cell comprises a positive electrode and a negative electrode, wherein the positive electrode and the negative electrode each comprise a busbar electrode, a finger electrode, and a bonding pad located on the busbar electrode, the busbar electrode intersecting with the finger electrode. The method comprises: after an insulating adhesive is printed on at least the finger electrodes with different polarities on side edges of a positive electrode and a negative electrode in a solar cell, printing an electrically conductive adhesive on bonding pads, wherein the printing height of the electrically conductive adhesive is greater than or equal to the printing height of the insulating adhesive; and on the basis of the electrically conductive adhesive and the bonding pads, connecting at least two batteries in series, so as to form a battery string. In the present application, an insulating adhesive is printed to cover finger lines on the edge of a bonding pad, and an electrically conductive adhesive is additionally printed on the bonding pad, thereby eliminating a height difference formed between an electrically conductive wire and the bonding pad due to the presence of the insulating adhesive, and solving the problem of pseudo soldering of a battery.

Description

A kind of welding method and photovoltaic component

This application claims priority to the Chinese patent application filed with the China Patent Office on September 14, 2022, with application number 202211117164.3 and titled "A welding method and photovoltaic module", the entire content of which is incorporated into this application by reference.

Technical field

This application relates to the field of solar photovoltaic technology, and in particular to a welding method and photovoltaic components.

Background technique

Interdigitated back contact (IBC) solar cells refer to solar cells with no electrodes on the front of the cell, and both positive and negative electrodes are set on the back of the cell. This can reduce the shielding of the cell by the electrodes, increase the short-circuit current of the cell, and improve The energy conversion efficiency of the cell.

The existing back-contact solar cells use multi-busbar electrode technology (MULTI-BUSBAR, MBB) to set the electrodes on the back side of the cell. That is, the positive electrode on the back of the cell includes a positive main grid electrode and a positive fine grid, and the negative electrode includes a negative main grid electrode. And the negative electrode fine grid, the positive electrode main grid electrode and the negative electrode main grid electrode are arranged in parallel, the positive electrode fine grid and the negative electrode fine grid are arranged in a finger shape, and the main grid electrodes and the fine grids of the same polarity are connected to each other, and the positive electrode fine grid and the negative electrode fine grid are connected to each other. The main gate electrode and the fine gate are isolated from each other to avoid short circuits.

When back-contact solar cells are assembled into photovoltaic modules, solder ribbons are often used to connect adjacent cells. Because the positive electrode fine grid lines and the negative electrode fine grid lines are staggered on the back of the battery cells, when using solder ribbons to connect adjacent battery cells, it is necessary to use insulating glue to print the fine grid lines on both sides of the main grid electrode to prevent heterogeneous grids when the solder ribbons are interconnected. The wire connection is short-circuited.

However, the insulating glue printed on the fine grid lines will form a certain height, which will cause a height difference between the solder ribbon and the solder pad during welding, resulting in abnormal welding and affecting the quality of photovoltaic modules.

Application content

This application provides a welding method and photovoltaic module, aiming to reduce the problem of false welding during the welding process of back-contact solar cells and conductive wires, and improve the welding quality.

In a first aspect, embodiments of the present application provide a welding method for welding back-contact solar cells, wherein the cells include positive electrodes and negative electrodes, and the positive electrodes and negative electrodes include main grid electrodes, thin The gate electrode and the pad located on the main gate electrode, the main gate electrode and the The fine gate electrodes intersect;

The methods include:

At least after printing insulating glue on the opposite-shaped fine gate electrodes on the sides of the positive electrode and negative electrode in the battery piece, conductive glue is printed on the pad; the printing height of the conductive glue is greater than or equal to the printing height of the insulating glue;

Based on the conductive glue and the soldering pad, at least two batteries are connected in series to form a battery string.

Optionally, the welding method also includes:

Cut the battery sheet printed with conductive adhesive into half sheets and process them into battery half sheets;

Based on the conductive glue and the pad, at least two batteries are connected in series to form a battery string, including:

Based on the conductive adhesive and the soldering pad, at least two battery halves are serially welded using multiple welding ribbons to form a battery string.

Optionally, in the welding method, the negative electrode is a silver electrode, the positive electrode is an aluminum electrode, both the positive electrode pad and the negative electrode pad are silver pads, and the positive electrode The outer periphery of the pad is equipped with an aluminum frame;

In the step of printing conductive glue on the pad, the size of the conductive glue printed on the positive electrode pad in the battery sheet is controlled to be smaller than the size of the conductive glue printed on the negative electrode pad.

Optionally, in the soldering method, in the step of printing conductive glue on the soldering pads, conductive glue forming at least two soldering points is printed on each of the soldering pads.

Optionally, in the welding method, when printing insulating glue on the opposite-shaped fine grid electrodes on the sides of the positive electrode and negative electrode in the battery sheet, the printing width of the insulating glue is controlled to be greater than the width of the opposite-shaped fine grid electrode, and the The printing width of the insulating glue covers the anisotropic fine gate electrode, and the width is the width along the extending direction of the fine gate electrode.

Optionally, before using a plurality of welding strips to string-weld at least two battery halves, the welding method further includes:

The thickness of the tin layer on the surface of each soldering strip is thinned. After the thinning process, the thickness of the tin layer of the soldering strip is 3 to 10 μm;

And/or flatten both ends of the welding ribbon, and the flattening length of the welding ribbon is 1 to 10 mm.

Optionally, in the welding method, the plurality of welding strips include a first welding strip, a second welding strip and a third welding strip;

Use multiple welding ribbons to string-weld at least two battery halves, including:

Weld one end of the third solder ribbon to at least one negative electrode pad on the battery half piece, and connect all The other end of the third welding ribbon is welded to at least one positive electrode pad on the adjacent battery half piece;

For the first battery half-piece located at the beginning of the battery string, extend one end of the first soldering strip and weld it to the first bus bar, and connect the other end of the first soldering strip to at least one positive electrode pad on the battery half-sheet. perform welding;

For the second battery half-piece located at the end of the battery string, weld one end of the second welding ribbon to at least one negative electrode pad on the second battery half-piece, and extend the other end of the second welding ribbon and connect it with Second bus bar welding.

Optionally, in the welding method, one end of the first welding strip is extended and welded to the first bus bar, including:

Apply flux to the first bus bar in advance, and then extend one end of the first soldering strip and weld it to the first bus bar;

Extend the other end of the second soldering strip and weld it to the second bus bar, including:

Apply flux to the second bus bar in advance, and then extend the other end of the second soldering strip and weld it to the second bus bar.

Optionally, before using a plurality of welding ribbons to string-weld at least two battery halves, the method further includes:

Black expandable polyethylene is disposed between two adjacent battery halves, between the first battery half and the first bus bar, and between the second battery half and the second bus bar.

In a second aspect, embodiments of the present application provide a photovoltaic module, which is welded by the above-mentioned welding method.

In the embodiment of the present application, at least after printing insulating glue on the opposite-shaped thin gate electrodes on the sides of the positive electrode and negative electrode in the battery piece, conductive glue is printed on the pad at the main gate electrode, and the printing height of the conductive glue is greater than or equal to the insulation Glue printing height, and then based on the conductive glue and pads, at least two batteries are connected in series to form a battery string. In this application, by printing insulating glue to cover the thin grid lines at the edge of the pad, and additionally printing conductive glue on the pad, it not only reduces the risk of battery grid breakage and the short circuit of heterosexual grid lines when interconnecting conductive wires, but also eliminates the need for conductive The height difference between the wire and the pad caused by the presence of insulating glue solves the problem of weak soldering of conductive wires.

Description of drawings

In order to explain the technical solutions of the embodiments of the present application more clearly, the drawings needed to be used in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. , for those of ordinary skill in the field, without exerting creativity Subject to availability, other drawings can also be obtained based on these drawings.

Figure 1 shows a step flow chart of a welding method in an embodiment of the present application;

Figure 2 shows a schematic structural diagram of the back contact cell sheet in the embodiment of the present application;

Figure 3 shows a schematic structural diagram of the photovoltaic module in the embodiment of the present application;

Figure 4 shows a partial enlarged view of part G in Figure 3;

Figure 5 shows a schematic diagram of the first angle printing of conductive adhesive in the embodiment of the present application;

Figure 6 shows a schematic diagram of the second angle printing of conductive adhesive in the embodiment of the present application;

Figure 7 shows a schematic structural diagram of the welding strip after flattening in the embodiment of the present application.

Specific embodiments

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

Before describing the embodiments of the present application in detail, the application scenarios of the embodiments of the present application are first introduced.

When assembling back-contact solar cells to obtain a photovoltaic module, one end of the conductive wire is connected to the positive main grid on the back of the cell, and extends along the positive main grid to the negative main grid on the back of the adjacent cell. The other end of the conductive wire One end is connected to part of the negative main grid, thereby conducting the current collected by the positive main grid and the negative main grid, and connecting two adjacent back-contact solar cells in series. At the same time, in order to prevent the conductive wire from being short-circuited when it is connected to the main grid electrode in the battery sheet and the fine grid electrode of opposite polarity, an insulating layer needs to be installed in the battery sheet except where the main grid electrode is connected to the conductive wire. In this way, even if the conductive line connected to the main gate electrode is offset to a certain extent, it will not come into contact with the thin gate electrode of the opposite polarity.

However, the insulating glue printed on the fine grid lines will form a certain height, which will cause a height difference between the conductive lines and the pads during welding, resulting in abnormal welding and affecting the quality of the photovoltaic modules.

Based on the above problems, embodiments of the present application provide a welding method and photovoltaic module, aiming to reduce the problem of virtual soldering between back contact solar cells and conductive wires caused by printing insulating glue on the side of the main grid, and improve the performance of photovoltaic modules. Welding quality.

Referring to Figure 1, Figure 1 shows a step flow chart of a welding method according to an embodiment of the present application. The method is used to weld back-contact solar cells. The cells include positive electrodes and negative electrodes. The positive electrodes and negative electrodes include main The gate electrode, the fine gate electrode and the pad located on the main gate electrode, the main gate electrode The electrode intersects the fine gate electrode; the method may include steps 101 to 102.

As shown in Figure 2, the back contact battery sheet in the embodiment of the present application includes: a semiconductor substrate 10, and a positive electrode 20 and a negative electrode 30 provided on the backlight surface of the semiconductor substrate 10. The positive electrode 20 may in turn include a positive main grid electrode. 21 and a positive fine gate electrode 22. The negative electrode 30 may further include a negative main gate electrode 31 and a negative fine gate electrode 32. The positive main gate electrode 21 and the negative main gate electrode 31 are arranged parallel to and spaced apart from each other along the first direction A. The positive fine gate electrode 30 The gate electrode 22 and the negative fine gate electrode 32 are parallel to and spaced apart from each other along the second direction B, that is, the positive fine gate electrode 22 and the negative fine gate electrode 32 are arranged in a finger-like intersecting manner, and the first direction A and the second direction B are not parallel to each other. , in one case of the embodiment of the present application, the first direction A may be perpendicular to the second direction B.

At the same time, since the positive fine gate electrode 22 is distributed on the surface of the semiconductor substrate 10, it is used to collect the positively charged carriers generated on the surface of the semiconductor substrate 10, and transport and gather the collected positively charged carriers to the positive electrode main body. The gate electrode 21 , that is, the current is formed and converged in the positive fine gate electrode 22 and the positive main gate electrode 21 ; the negative fine gate electrode 32 is distributed on the surface of the semiconductor substrate 10 and is used to collect the negatively charged carriers generated on the surface of the semiconductor substrate 10 , and transport and converge the collected negatively charged carriers to the negative main gate electrode 31 , that is, a current is formed and converged in the negative fine gate electrode 32 and the negative main gate electrode 31 . Therefore, the positive fine gate electrode 22 is connected to the positive main gate electrode 21 and is separated from the negative main gate electrode 31 by a first preset distance, that is, one end C of the positive fine gate electrode 22 is connected to the positive main gate electrode 21, and the other end D (th The two end points) are separated from the negative main grid electrode 31 by a first preset distance to achieve disconnection from the negative main grid electrode 31 to avoid short circuit; the negative fine gate electrode 32 is connected to the negative main grid electrode 31 and connected to the positive main grid. The electrodes 21 are separated by a second preset distance, that is, one end E of the negative fine gate electrode 32 is connected to the negative main gate electrode 31, and the other end F (first endpoint) is separated from the positive main gate electrode 21 by a second preset distance. It achieves disconnection from the positive main gate electrode 21 to avoid short circuit.

The first preset distance and the second preset distance may be equal or unequal. The first preset distance and the second preset distance may not occur between the main gate electrode and the fine gate electrode with opposite polarity. spacing during short circuit.

Multiple IBC solar cells can be interconnected through conductive wires to form a photovoltaic module, as shown in Figure 3, so that the current generated and accumulated in the multiple solar cells can be further collected to power external devices.

Specifically, the positive main grid electrode 21 in the cell sheet may include: a plurality of first pads 211 for connecting to conductive wires, and positive connection grid lines 212 connecting adjacent first pads 211; a negative main grid The electrode 31 may include: a plurality of second pads 311 for connecting to conductive lines, and connecting The negative electrode of the adjacent second bonding pad 311 is connected to the gate line 312 . Correspondingly, one end C of the positive fine gate electrode 22 is connected to the first bonding pad 211 or the positive electrode connecting grid line 212, and the other end D (the second endpoint) is connected to the second bonding pad 311 or the negative electrode connecting grid line 312 at a first predetermined distance. Distance; one end E of the negative fine gate electrode 32 is connected to the negative connection point 311 or the negative connection grid line 312, and the other end F (first end point) is separated from the positive connection point 211 or the positive connection grid line 212 by a second preset distance.

Specifically, when using conductive wires to connect adjacent solar cells, the first soldering pad 211 and the second soldering pad 311 can be used as welding points to be welded to the conductive wires, so that the conductive wires are along the positive main grid electrode 21 and the negative main grid electrode. 31 extension.

Step 101: After at least printing insulating glue on the opposite-shaped fine gate electrodes on the sides of the positive electrode and negative electrode in the battery sheet, conductive glue is printed on the pad; the printing height of the conductive glue is greater than or equal to the insulating glue Printing height.

In this step, as shown in Figures 3 to 6, the main grid electrode includes the positive main grid electrode 21 and the negative main grid electrode 31, and the bonding pads include the above-mentioned first bonding pad 211 and the second bonding pad 311. After printing insulating glue 40 on at least part of one side or both sides of the gate electrode, conductive glue 50 is printed on the pad on the main gate electrode; wherein at least part of the above includes the first endpoint of the anisotropic fine gate close to the main gate, That is, it can be effectively avoided that when the conductive wire 60 is used for series welding with other cells in the later stage, even if the conductive wire 60 connected to the main grid electrode is offset to a certain extent, it will not come into contact with the fine grid electrode of the opposite polarity. .

In this step, when using the conductive wires 60 to weld multiple battery cells in series, the conductive wires 60 need to be welded to multiple pads, and the insulating glue 40 printed on the thin grid lines will form a certain height, which makes There will be a height difference between the conductive wire 60 and the soldering pad due to the protrusion of the insulating glue 40, which will lead to abnormal welding between the conductive wire 60 and the soldering pad, affecting the quality of the photovoltaic module. In the embodiment of the present application, there is an additional step at the soldering pad. The conductive adhesive 50 is printed to fill the height difference between the conductive line 60 and the pad, so that when the pad and the conductive line 60 are welded, welding based on the conductive adhesive 50 can effectively avoid the gap between the conductive line 60 and the pad. Welding problem.

In the embodiment of the present application, the back-contact solar cell sheet may specifically have a side length of 166 mm, 182 mm or 210 mm, etc. The number of the above-mentioned main grid electrodes can be 6 to 25; the above-mentioned pads are silver pads, and the pads can be rectangular, circular or oval, with a size of 0.5-5mm, and the pads at the beginning and end of the main grid electrodes The distance to the edge of the cell is 0~10mm.

Optionally, the number of the main grid electrodes can be 15, the pads are rectangular, and the size is 2*3mm, and the distance between the pads at the beginning and end of the main grid electrodes and the battery sheet is 3mm to prevent the battery sheet from cracking.

In the welding method provided by the embodiment of the present application, during the process of printing the insulating glue 40 on the opposite-shaped fine grid electrodes on the sides of the positive electrode and the negative electrode in the battery sheet, the printing width of the insulating glue 40 is controlled to be greater than the width of the opposite-shaped fine grid electrode, and The printing width of the insulating glue 40 is controlled to cover the anisotropic fine gates of the main gate electrodes, and the width is the width along the extending direction of the fine gate electrodes. Among them, by covering the fine grid lines at the edge of the pad with the printed insulating glue 40, it can not only avoid the short circuit caused by the contact between the main grid electrode and the fine grid electrode of the opposite polarity when the conductive wire 60 is used for series welding with other cells. It can also effectively reduce the risk of battery breakage.

Optionally, in the welding method provided in this application, the printing width of the insulating glue 40 is 1.5-10 mm, and the printing height of the insulating glue 40 is 10-80 μm. For example, the printing width of the insulating glue 40 is controlled to be 4.8 mm, and the printing height of the insulating glue 40 is controlled to be 40 μm.

In the embodiment of the present application, the printed shape of the conductive adhesive 50 may be a cube, an elliptical cylinder, a cylinder, etc.

Optionally, in the described welding method, in the step of printing the conductive adhesive 50 on the pad at the main gate electrode, the conductive adhesive 50 has a length, width, and height of 1 to 2 mm, 1 to 2 mm, and 0.1 to 1 mm respectively. cube.

Optionally, in the embodiment of the present application, the above-mentioned negative electrode is a silver electrode, the above-mentioned positive electrode is an aluminum electrode, the positive electrode pad and the negative electrode pad are both silver pads, and the periphery of the pad of the negative electrode is provided with Aluminum frame;

In the embodiment of the present application, the back-contact solar cell positive electrode pad (i.e., the first pad 211 and the negative electrode pad (i.e., the second pad 311)) have different base textures, and the first pad is provided with an aluminum Block 213; In the step of printing the conductive adhesive 50 on the pad at the main grid electrode, control the size of the conductive adhesive 50 printed on the first pad 211 in the cell sheet to be smaller than the size of the conductive adhesive 50 printed on the second pad 311.

Among them, because the conductive glue 50 melts during the welding process, the silver in the pad connects to the conductive glue 50 and then connects to the conductive wire 60. During this process, a "silver eating" phenomenon occurs, causing the height of the conductive glue 50 to decrease. Therefore, in order to ensure the welding pulling force, it is necessary to set the size of the conductive adhesive 50 in the first pad 211 to be smaller than the size of the conductive adhesive 50 in the second pad 311, so as to reduce the "silver eating" phenomenon on the second pad and prevent the silver from being consumed. Due to the existence of the aluminum frame, the conductive wires are overhead and cannot fully contact the conductive adhesive.

Optionally, the area of the conductive glue printed on the positive electrode pad is half of the area of the conductive glue printed on the negative electrode pad.

Optionally, in the described welding method, the length, width, and height of the conductive glue 50 at the positive electrode pad are 0.5mm, 0.5mm, and 0.15mm respectively, and the length, width, and height of the conductive glue 50 at the negative electrode pad are 0.5 mm, 0.5 mm, and 0.15 mm respectively. They are 1mm, 1mm, and 0.15mm respectively.

Considering that when using conductive wires 60 for series connection, the welding quality at the beginning and end positions is more critical, and it is also necessary to cut the battery sheet into two half-pieces along the middle position of the vertical main grid electrode, so that the main grid electrode is at the middle position. Become the first and last positions of the new conductive lines 60 for string welding. Therefore, in the step of printing the conductive glue 50 on the pads at the main grid electrode, the first and last positions and the middle position pads of the main grid electrode are printed to form conductive double solder joints. Glue 50 to prevent the conductive glue 50 from being in contact with the conductive wire 60 due to offset of the conductive wire 60, resulting in a false soldering situation. Among them, the printing effect of the conductive adhesive 50 is specifically shown in Figure 3. Among them, except for the first and last positions and the middle position of the main gate electrode, conductive adhesive 50 of a single solder joint is printed on other pads to save the amount of conductive adhesive 50 .

Optionally, in one embodiment, in the step of printing conductive glue on the soldering pads, conductive glue forming double solder joints is printed on each of the soldering pads.

In this embodiment, by printing conductive glue to form double solder joints on each pad, not only can the conductive glue 50 not be able to contact the conductive line 60 due to the deviation of the conductive line 60, and thus the occurrence of a false solder, it can also be ensured that the battery After the sheet is cut in half, there is still enough conductive glue and conductive wire at the pad of each battery half for welding.

Optionally, the pads at the head and tail positions and the middle position of the main gate electrode are wider than the pads at other positions, that is, the head and tail positions and the middle position of the main gate electrode are widened to better print the conductive conductors forming the double solder joints. Glue 50. Optionally, the size of the above-mentioned widened pad is 4*3mm.

Step 102: Connect at least two batteries in series based on the conductive adhesive and the pad to form a battery string.

In this step, the conductive glue 50 melts during the welding process, so that the silver in the pad is connected to the conductive glue 50, and at the same time the conductive glue 50 is connected to the pad, thereby realizing the welding of the pad and the conductive wire 60, and obtaining the above-mentioned battery string. In the lamination process, multiple battery strings are welded through bus bars to obtain photovoltaic modules. In this step, due to the presence of the conductive adhesive 50, the use of flux can be omitted.

The welding method provided by the embodiment of the present application is used to weld back-contact solar cells. At least after printing insulating glue on the opposite-shaped fine grid electrodes on the sides of the positive electrode and negative electrode in the cell, it is printed on the pad at the main grid electrode. conductive glue, and the printing height of the conductive glue is greater than or equal to the printing height of the insulating glue. Then based on the conductive glue and the pad, at least two batteries are welded in series to form a battery string. In this application, by printing insulating glue to cover the thin grid lines at the edge of the pad, and additionally printing conductive glue on the pad, it not only reduces the risk of battery grid breakage and the short circuit of heterosexual grid lines when interconnecting conductive wires, but also eliminates the need for conductive The height difference between the wire and the pad caused by the presence of insulating glue solves the problem of weak soldering of conductive wires.

The welding method provided by the embodiment of the present application further includes step 103 before the above step 102, and the above step 102 specifically includes step 1021.

Step 103: Cut the battery sheet printed with conductive adhesive into half sheets and process them into battery half sheets.

In this step, the battery sheet is cut into two half-sheets along the middle position of the vertical main grid, which are the above-mentioned battery half-sheets. Among them, the top corners of the two battery slices located on both sides of the main grid electrode are chamfered, so that after the battery is cut into half slices, the other half of the battery slice does not need to be rotated 180°, so that the cut edge of the battery can be interconnected with the soldering strip 61 of the other cut edge. The chamfered edge is interconnected with the chamfered edge welding strip 61 of another battery.

Step 1021: Based on the conductive adhesive and the soldering pad, use multiple welding ribbons to string-weld at least two battery halves to form a battery string.

Among them, the conductive wire 60 can be a welding strip 61, and the welding strip 61 can be a conventional flat welding strip, a round welding strip, or a triangular welding strip. Specifically, it can be a flat welding strip to better contact the conductive adhesive 50 and the pad, and improve the Welding fastness.

Optionally, in one embodiment, the plurality of welding strips include a first welding strip, a second welding strip and a third welding strip;

The above step 102 includes steps 201 to 203:

Step 201: Weld one end of the third welding ribbon to at least one negative electrode pad on the battery half-chip, and weld the other end of the third welding ribbon to at least one positive electrode pad on the adjacent battery half-chip;

Step 202: For the first battery half-piece located at the head of the battery string, extend one end of the first welding strip and weld it to the first bus bar, and connect the other end of the first welding strip to at least one positive electrode on the battery half-piece. Electrode pads for welding;

Step 203: For the second battery half-piece located at the end of the battery string, weld one end of the second welding ribbon to at least one negative electrode pad on the second battery half-piece, and extend the other end of the second welding ribbon. out and soldered to the second bus bar.

In this embodiment, one end of the welding ribbon 61 is connected to the positive main grid electrode on the back of the battery half, and extends along the positive main grid electrode 21 to the negative main grid on the back of the adjacent battery half. The other end of the welding ribbon is connected to the negative electrode. Parts of the main grid electrodes are connected, thereby conducting the current collected by the positive main grid electrode 21 and the negative main grid electrode 31, and connecting two adjacent back contact solar cells in series;

At the same time, in order to assemble the photovoltaic module, it is necessary to use bus bars 70 to connect multiple battery strings. Therefore, the positive main grid electrode 21 and the first bus bar of the first battery half piece are connected to the two sides of the solder ribbon respectively. End welding, and welding and connecting the negative main grid electrode 31 and the second bus bar of the last half-cell cell to the two ends of the soldering strip, thereby connecting and conducting multiple cell strings, and then assembling the photovoltaic module.

Optionally, in a specific implementation, the welding method provided by the embodiment of the present application further includes step 104 before the above step 1021:

Step 104: Thin the tin layer thickness on the surface of each soldering strip.

In this specific embodiment, because the conductive glue 50 is printed on the soldering pads, the conductive glue 50 will melt during the welding process, making it firmly connected to the soldering pad and the soldering strip. Therefore, there is no need to consider the soldering effect of the tin layer of the soldering strip itself, so it can Reducing the thickness of the tin layer on the surface of the soldering strip 61 can not only save the cost of the soldering strip 61, but also reduce the risk of grid breakage when the silver grid wire has no insulating glue 40.

Optionally, the thickness of the tin layer of the solder strip 61 after the thinning process is 3 to 10 μm, for example, 5 μm.

Optionally, in a specific implementation method, extending one end of the first welding strip and welding it to the first bus bar includes:

In this specific embodiment, because the thickness of the tin layer on the surface of the soldering strip 61 is thinned and there is no conductive adhesive 50 at the bus bar, in order to ensure the welding effect between the soldering strip 61 and the bus bar, the first Apply flux to the first bus bar connected to the first battery half and to the second bus bar connected to the last second battery half, and then solder the flux to the first bus bar extending from the direction of the positive main grid electrode of the first battery half. Welding with the ribbon 61, or welding with the ribbon 61 extending from the direction of the negative main grid electrode of the second battery half, thereby respectively connecting the positive electrode of the first battery half with the first bus bar, and the negative electrode of the second battery half with the third bus bar. Two busbar connections.

Optionally, in one embodiment, the welding method provided by the embodiment of the present application further includes: before using multiple welding strips to string-weld at least two battery half-pieces:

Step 105: Flatten both ends of the welding strip.

In this embodiment, both ends of the cut welding ribbon 61 are flattened to prevent the welding ribbon 61 from piercing the insulating glue 40 and causing a welding short circuit due to the electrode grid lines of the opposite sex. At the same time, the flattened welding ribbon 61 can Increase the welding area and improve the welding yield. Among them, the welding strip 61 after the flattening process is shown in FIG. 7 .

Optionally, the flattened length of the welding strip 61 is 1 to 10 mm, for example, 3 mm.

Step 106: Arrange black expandable polyethylene between two adjacent battery halves, between the first battery half and the first bus bar, and between the second battery half and the second bus bar.

In this embodiment, by arranging black intensifiers between two adjacent battery halves that need to be serially welded, between the first battery half and the first bus bar, and between the last battery half and the second bus bar, Polyethylene 80 is used to fill the gaps, shield all the welding strips 61 for subsequent string welding, protect the welding strips 61, and make the overall structure more beautiful.

Wherein, the black expandable polyethylene 80 provided above may specifically be a small strip of high temperature resistant black expandable polyethylene tape.

The usage width of black expandable polyethylene 80 is determined based on the actual gap between the battery halves. Optionally, the width of the black expandable polyethylene 80 between battery strings is greater than the width between battery halves.

An embodiment of the present application also provides a photovoltaic module, which is prepared by the above-mentioned welding method.

Among them, in the process of welding to prepare the above-mentioned photovoltaic modules, not only insulating glue is printed on both sides of the main grid of the cell, but also conductive glue is printed on the pads. The printing height of the conductive glue is greater than or equal to the printing height of the insulating glue, eliminating the need for soldering strips and pads. The height difference solves the problem of abnormal welding of conductive wires, and the printed insulating glue covers the thin grid lines on the edge of the pad, which can effectively reduce the risk of battery grid breakage. Therefore, the photovoltaic module provided by the embodiment of the present application has good welding effect, high yield, and strong grid lines, so it has stable quality and durability.

It should be noted that for the sake of simple description, the method embodiments are expressed as a series of action combinations. However, those skilled in the art should know that the embodiments of the present application are not limited by the described action sequence, because According to the embodiments of the present application, certain steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily necessary for the embodiments of the present application.

It should be noted that, in this document, the terms "comprising", "comprises" or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or device that includes a series of elements not only includes those elements, It also includes other elements not expressly listed or inherent in the process, method, article or apparatus. Without further limitation, an element defined by the statement "comprises a..." does not exclude the presence of additional identical elements in a process, method, article or apparatus that includes that element.

Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus the necessary general hardware platform. Of course, they can also be implemented by over hardware, but in many cases the former is the better implementation. Based on this understanding, the technical solution of the present application can be embodied in the form of a software product in essence or that contributes to the existing technology. The computer software product is stored in a storage medium (such as ROM/RAM, disk, CD), including several instructions to cause a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in various embodiments of this application.

The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above-mentioned specific implementations. The above-mentioned specific implementations are only illustrative and not restrictive. Those of ordinary skill in the art will Inspired by this application, many forms can be made without departing from the purpose of this application and the scope protected by the claims, and these all fall within the protection of this application.

Claims

A welding method, which is used to weld back-contact solar cells. The cells include positive electrodes and negative electrodes. The positive electrodes and negative electrodes include main grid electrodes, fine grid electrodes and welding electrodes located on the main grid electrodes. Disk, the main gate electrode intersects the fine gate electrode;

The methods include:

At least after printing insulating glue on the opposite-shaped fine gate electrodes on the sides of the positive electrode and negative electrode in the battery piece, conductive glue is printed on the pad; the printing height of the conductive glue is greater than or equal to the printing height of the insulating glue;

Based on the conductive glue and the soldering pad, at least two batteries are connected in series to form a battery string.
The welding method according to claim 1, wherein the method further includes:

Cut the battery sheet printed with conductive adhesive into half sheets and process them into battery half sheets;

Based on the conductive glue and the pad, at least two batteries are connected in series to form a battery string, including:

Based on the conductive adhesive and the soldering pad, at least two battery halves are serially welded using multiple welding ribbons to form a battery string.
The welding method according to claim 1, wherein the negative electrode is a silver electrode, the positive electrode is an aluminum electrode, both the positive electrode pad and the negative electrode pad are silver pads, and the positive electrode An aluminum frame is provided on the outer periphery of the electrode pad;

In the step of printing conductive glue on the pad, the size of the conductive glue printed on the positive electrode pad in the battery sheet is controlled to be smaller than the size of the conductive glue printed on the negative electrode pad.
The soldering method according to claim 1, wherein in the step of printing conductive glue on the bonding pads, conductive glue forming at least two solder joints is printed on each of the bonding pads.
The welding method according to claim 1, wherein when printing insulating glue on the opposite-shaped fine grid electrodes on the sides of the positive electrode and the negative electrode in the battery sheet, the printing width of the insulating glue is controlled to be greater than the width of the opposite-shaped fine grid electrode, and The printing width of the insulating glue is controlled to cover the anisotropic fine gate electrode, and the width is the width along the extending direction of the fine gate electrode.
The welding method according to claim 2, wherein before using a plurality of welding strips to string-weld at least two battery half-pieces, it further includes:

The thickness of the tin layer on the surface of each soldering strip is thinned, and the thickness of the tin layer of the soldering strip after the thinning treatment is 3 to 10 μm; and/or the two ends of the soldering strip are flattened, and the soldering strip is pressed The flat length is 1～10mm.
The welding method according to claim 2, wherein the plurality of welding strips include a first welding strip, a second welding strip and a third welding strip;

Use multiple welding ribbons to string-weld at least two battery halves, including:

Welding one end of the third welding strip to at least one negative electrode pad on the battery half-piece, and welding the other end of the third welding strip to at least one positive electrode pad on the adjacent battery half-piece;

For the first battery half-piece located at the beginning of the battery string, extend one end of the first soldering strip and weld it to the first bus bar, and connect the other end of the first soldering strip to at least one positive electrode pad on the battery half-sheet. perform welding;

For the second battery half-piece located at the end of the battery string, weld one end of the second welding ribbon to at least one negative electrode pad on the second battery half-piece, and extend the other end of the second welding ribbon and connect it with Second bus bar welding.
The welding method according to claim 7, wherein extending one end of the first welding strip and welding it to the first bus bar includes:

Apply flux to the first bus bar in advance, and then extend one end of the first soldering strip and weld it to the first bus bar;

Extend the other end of the second soldering strip and weld it to the second bus bar, including:

Apply flux to the second bus bar in advance, and then extend the other end of the second soldering strip and weld it to the second bus bar.
The welding method according to claim 7, wherein before using a plurality of welding strips to string-weld at least two battery halves, the method further includes:

Black expandable polyethylene is disposed between two adjacent battery halves, between the first battery half and the first bus bar, and between the second battery half and the second bus bar.
A photovoltaic module, which is welded by the welding method according to any one of claims 1 to 9.