Solder strip, solar cell module welding method and solar cell module

Abstract

According to the welding strip and the welding method of the solar cell module, the welding strip comprises bending parts, the bending parts are arranged between every two adjacent connecting parts in the length direction of the welding strip, each bending part comprises at least one protrusion, the length of the part, between every two adjacent connecting parts, of the welding strip is 1.005-1.05 times of the distance between every two adjacent connecting parts, and the height of each bending part is 50-200 microns. During welding, the welding strips and the battery pieces are arranged one by one, and the welding strips are welded on the bonding pads of the solar battery pieces. According to the welding strip and the welding method, the welding strip comprises the bent part, and the bent part is located between the two connecting parts in the length direction of the welding strip; the bending portion comprises at least one protrusion, during welding, the welding strip is placed on the solar cell, the connecting portion makes contact with the surface of the solar cell, after welding is cooled, the welding strip shrinks, the bending portion between adjacent welding spots shrinks and becomes straight, the situation that in the prior art, shrinkage causes tensile stress to the cell is avoided, and therefore hidden cracks of the cell are avoided.

Description

Technical Field

[0001] The present application belongs to the technical field of solar cell processing, and relates to a welding strip, a solar cell module welding method and a solar cell module. Background Art

[0002] When a solar cell module is welded, one or more welding ribbons are needed to connect adjacent cells and the welding ribbons are welded to the welding pads of the solar cell.

[0003] In the prior art, when welding solar cell modules, laser, infrared and other heating methods are usually used to melt the welding ribbon and weld it on the pad. Due to the different thermal expansion coefficients of the welding ribbon and the solar cell, the welding ribbon shrinks when cooling after heating and welding, which can easily cause the cell to warp to a certain extent, resulting in hidden cracks in the cell. In solving this problem, the prior art adopts the method of heating the welded welding ribbon and the cell as a whole and pressing down, which can eliminate the warping of the cell to a certain extent. However, this method cannot completely solve the problem of cell warping, and when pressing down, the cell will also cause hidden cracks due to the pressure. Summary of the invention

[0004] The present invention aims to solve the technical problem that when a solar cell module is welded, due to the different thermal expansion coefficients of the welding ribbon and the solar cell, the welding ribbon shrinks when cooling after heating and welding, which easily causes the cell to warp to a certain extent, resulting in hidden cracks in the cell.

[0005] In order to solve the problems of the prior art, the present invention adopts the following technical solutions.

[0006] On the one hand, the present invention provides a welding strip, which includes at least a connecting portion and a bending portion. In the length direction of the welding strip, a bending portion is provided between every two adjacent connecting portions, and the bending portion includes at least one protrusion.

[0007] In an optional implementation, the connection portion corresponds to a welding point of a solar cell.

[0008] In an optional embodiment, the curved portion is a curved protrusion or a trapezoidal protrusion.

[0009] In an optional embodiment, a straight middle portion is provided between the curved portion and the connecting portion.

[0010] In an optional embodiment, the connecting portion is a concave portion having a direction opposite to the convex direction of the curved portion.

[0011] In an optional embodiment, the depth of the recess is 20-50 μm.

[0012] In an optional embodiment, both ends of the welding strip are straight.

[0013] In an optional embodiment, the length of the welding strip between adjacent connecting portions is 1.005-1.05 times the distance between adjacent connecting portions.

[0014] In an alternative embodiment, the height of the curved portion is 50-250 μm.

[0015] In an alternative embodiment, the height of the curved portion is 100-200 μm.

[0016] In an optional embodiment, the distance between adjacent connecting parts is 10-20 mm.

[0017] In an optional embodiment, the distance between the two ends of the curved portion is 4-9 mm.

[0018] In an optional embodiment, the ratio of the length of the weld band to the distance between adjacent connection portions at approximately the middle of the weld band and / or approximately one quarter of the weld band and three quarters of the weld band is greater than the ratio of the length of the weld band to the distance between adjacent connection portions in the remaining part.

[0019] In another aspect, the present invention provides a method for welding a solar cell assembly, comprising the following steps:

[0020] The soldering ribbon and the battery cell are arranged one by one so that the connecting part of the soldering ribbon corresponds to the soldering pad of the battery cell, and the bent part protrudes upward relative to the solar cell, and the soldering ribbon is welded to the soldering pad of the solar cell. Before the soldering ribbon and the battery cell are arranged one by one, the soldering ribbon is also shaped to obtain the aforementioned soldering ribbon.

[0021] In an optional embodiment, the soldering ribbon is cut to a certain length as required and then shaped; or, the soldering ribbon is shaped and then cut to a required length.

[0022] In an optional embodiment, before arranging the welding ribbons and the solar cells one by one, a step of preparing an insulating layer for the solar cell is also included.

[0023] In an optional embodiment, a method for welding a solar cell assembly comprises the following steps:

[0024] S1 lays the solar cells and the welding ribbons on the solar cell back panel according to a preset pattern to obtain a solar cell module;

[0025] S2 places the solar cell assembly on a welding platform, covers the solar cell assembly of S2 with a flexible film, places the solar cell assembly in a closed space between the flexible film and the welding platform, and evacuates the closed space;

[0026] S3 irradiates the welding position by a laser beam arranged above the flexible film to complete the welding;

[0027] S4 removes the flexible film, covers the solar cell module with a packaging film and a cover plate, and laminates to obtain a solar cell module.

[0028] In an optional embodiment, the backplane includes a transparent base plate and a packaging film.

[0029] In an optional embodiment, a welding ribbon connects two adjacent battery cells, wherein the ratio of the welding ribbon length between corresponding welding points between adjacent battery cells to the distance between adjacent welding points and / or the ratio of the welding ribbon length between adjacent welding points corresponding to the middle of the battery cell to the distance between adjacent welding points is greater than the ratio of the rest.

[0030] On the other hand, the present invention also provides a solar cell module, which is prepared by the aforementioned solar cell module welding method, adjacent solar cells are connected by multiple parallel welding strips, the spacing between adjacent welding points on a welding strip before welding is 10-20mm, the length of the bending portion is 4-9mm, the bending portion has a protrusion, the height of the protrusion is 50-250μm, and the bending portion is located in the middle position between two adjacent welding points; after welding, the welding strips between the welding points are in straight contact with the solar cell.

[0031] In an optional embodiment, the ratio of the length of the solder strip between corresponding solder joints between adjacent battery cells to the distance between adjacent solder joints and / or the ratio of the length of the solder strip between adjacent solder joints corresponding to the middle of the battery cell to the distance between adjacent solder joints is greater than the ratio of the rest.

[0032] Through the above technical solution, this application achieves the following technical effects.

[0033] The welding strip and welding method of the present invention include at least one bending portion on the welding strip, and the bending portion is located between two connecting portions in the length direction of the welding strip; the bending portion includes at least one protrusion. During welding, the welding strip is placed on the solar cell, and the connecting portion contacts the surface of the solar cell. After the welding is cooled, the welding strip shrinks, and the bending portion between adjacent welding points shrinks and becomes straight, rather than shrinking and causing tensile stress on the cell as in the prior art, thereby avoiding hidden cracks in the cell. The welding strip is provided with a bending portion between each two connecting portions contacting the welding pad, which can ensure that the tensile stress is significantly reduced or not applied to different parts of the solar cell.

[0034] In the welding strip and welding method of the present invention, the concave portion of the connecting portion is exactly arranged in the concave welding pad and contacts the welding pad, which not only avoids the warping of the battery cell after welding, but also effectively avoids cold welding during the welding process.

[0035] The welding strip and welding method of the present invention can ensure that the welding strip is stably placed on the battery cell during welding. While the bending portion adapts to the cooling and shrinkage of the welding strip, the welding portion and the welding pad are kept in good contact when pressed down by the flexible film, so that the laser passing through the flexible film can achieve good welding.

[0036] In the solar cell assembly provided by the present invention, the solar cell sheet has close to zero warping, or its warping is much smaller than that of the solar cell assembly in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 A schematic diagram of the prior art showing that the solder strip is shortened after cooling after soldering, and the solar cell between two soldering points is subjected to tensile stress of the solder strip, resulting in warping of the solar cell;

[0039] Figure 2 A schematic diagram of placing a solder ribbon on a solar cell according to an embodiment of the present invention;

[0040] Figure 3 A schematic diagram of a welding strip according to an embodiment of the present invention;

[0041] Figure 4 Schematic diagram of a single ribbon before and after being welded to a solar cell according to an embodiment of the present invention;

[0042] Figure 5 A schematic diagram of placing a welding ribbon on a solar cell according to another embodiment of the present invention;

[0043] Figure 6 A schematic diagram of placing a solder ribbon on a solar cell according to an embodiment of the present invention;

[0044] Figure 7 This is a schematic diagram of placing a solder ribbon on two solar cells according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0046] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0047] Secondly, the present application is described in detail with reference to the schematic diagram. When describing the embodiments of the present application in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0048] In the prior art, when welding solar cell modules, laser, infrared and other welding methods are usually used to weld the welding ribbon to the pad. Due to the different thermal expansion coefficients of the welding ribbon and the solar cell, when cooling after welding, the welding ribbon shrinks and generates tension on the cell, which can easily cause a certain degree of warping of the cell, resulting in hidden cracks in the cell. Figure 1 Schematic diagram of the battery cell warping caused by the shortened solder strip during cooling after welding (arrow indicates the direction) and the tensile stress of the solder strip (arrow indicates the direction) between the two solder joints. The prior art solves this problem by heating the solder strip and the battery cell as a whole and then pressing them down flat, which can eliminate the warping of the battery cell to a certain extent. However, this method cannot completely solve the problem of battery cell warping, and the battery cell will also cause hidden cracks due to the pressure when it is pressed down.

[0049] In order to solve the problems existing in the prior art, the present invention provides a welding strip, see Figures 2 to 7 The welding ribbon includes at least one bending portion 12. In the length direction of the welding ribbon, the bending portion 12 is located between two adjacent connecting portions 11, and the bending portion 12 is set between adjacent connecting portions 11; the bending portion 12 includes at least one protrusion. Before welding, the welding ribbon is placed on the solar cell 20, and the connecting portion 11 contacts the pad on the surface of the solar cell, specifically, the position to be welded on the surface of the solar cell. Usually, the position to be welded is usually provided with a welding pad 21; the protrusion does not contact the surface of the solar cell 20. After the welding is cooled, the welding ribbon shrinks, and the bending portion 12 between adjacent welding points shrinks and becomes straight, rather than shrinking as in the prior art to cause tensile stress on the cell. It can be understood by those skilled in the art that the connecting portion 11 is the part that contacts the pad of the solar cell, and after the welding is completed, this connecting portion is the welding point.

[0050] The bent portion 12 of the present invention is provided to shrink and straighten the welded ... Figure 3, schematic diagrams of various shapes of the curved portion 12 are given, for example, the protrusion of the curved portion 12 can be arc-shaped, rectangular, trapezoidal or triangular.

[0051] Usually, one welding ribbon is used to weld two solar cells 20, and there are multiple corresponding positions to be welded, that is, multiple connecting portions 11 are arranged at intervals on the welding ribbon, and bending portions 12 are arranged between adjacent connecting portions 11. In this case, the welding ribbon includes multiple connecting portions 11 and multiple bending portions 12. Figure 2 An example of a welding strip having a plurality of connecting portions 11 and bending portions 12 is given. Generally, the bending portions 12 are all convex toward one direction.

[0052] As known to those skilled in the art, the surface of the solar cell has a conductive grid line, and the welding ribbon connects the grid lines of different poles of adjacent solar cells. Usually, a conductive pad 21 is provided on the solar cell 20, and the connecting portion 11 of the welding ribbon contacts and is welded to the pad 21, thereby achieving connection with the grid line.

[0053] Please continue to see Figure 2 and Figure 4 As an practicable method, the solder strip of the present invention has a straight connecting portion 11, which is disposed at the solder pad 21 when in use. Figure 2 and Figure 4 As shown, the soldering ribbon is placed on the battery cell 20, the connecting portion 11 is in contact with the solder pad 21, and the bent portion 12 protrudes upward relative to the battery cell 20. When cooled, the soldering ribbon shrinks and the bent portion 12 is straightened. Adjacent solder joints of the battery cell 20 are not subjected to the tension of the soldering ribbon, thereby avoiding warping of the battery cell.

[0054] For some P-type solar cells, the pad 21 is usually lower than the surface of the cell 20, forming a concave pad 21; for some N-type solar cells 20, although the pad 21 is not lower than the surface of the solar cell 20, in order to avoid the welding ribbon overlapping the grid line of the opposite sex and causing a short circuit during the assembly welding, the prior art applies insulating glue to the surface of the solar cell 20 to form an insulating layer. Obviously, no insulating glue is applied to the pad 21 to expose the pad 21 for welding with the welding ribbon. The insulating layer has a certain thickness and also forms a concave pad 21. In this case, if the connecting portion 11 is straight, there is a height difference between the connecting portion 11 of the welding ribbon and the pad 21, which will cause the welding ribbon and the pad 21 to have poor contact when welding, resulting in a cold solder joint.

[0055] In order to solve this problem, as a preferred embodiment, the welding strip of the present invention, the connecting portion 11 can be Figure 5 As shown, the concave portion in the opposite direction to the convex direction of the bent portion 12 can make better contact with the pad 21, effectively avoiding the situation of cold soldering. Figure 5The concave portion of the connecting portion 11 is just arranged in the concave solder pad 21 and contacts the solder pad 21, which not only avoids the warping of the battery cell after welding, but also effectively avoids cold soldering during the welding process.

[0056] It should be noted that, in the welding strip of the present invention, the protrusion of the curved portion 12 may be one or more protrusions arranged along the length direction, see Figure 6 The curved portion 12 and the connecting portion 11 may not be directly connected. In other words, there is a straight intermediate portion 13 of a certain length between the curved portion 12 and the connecting portion 11, see Figure 6 shown.

[0057] Preferably, the length L1 of the welding strip between adjacent connecting parts is 1.005-1.05 times of the distance D1 between adjacent connecting parts, and more preferably 1.01-1.03 times, so that after the welding strip shrinks, the length L1' of the welding strip after shrinkage between adjacent welding points is exactly equal to D1, that is, after shrinkage, the welding strip fits flatly on the battery cell and does not generate tensile stress on the battery cell.

[0058] The welding strip of the present invention can avoid the problem of hidden cracks in the battery cell after welding through the above technical solution. However, for laser welding of the whole panel assembly, the battery cell and the welding strip are usually arranged on the back plate of the solar cell assembly according to the preset pattern, and then covered by a flexible film. After the space covered by the flexible film is evacuated, the laser is passed through the flexible film to irradiate the welding position to complete the welding. Different from traditional string welding, during welding, it is necessary to ensure that the welding strip is placed stably on the battery cell, bend to adapt to the cooling and shrinkage of the welding strip, and maintain good fit between the connecting part and the pad when pressed down by the flexible film so that the laser passing through the flexible film can achieve good welding, etc.

[0059] The welding strip of the present invention solves the above problems in the following ways: the welding strip length L1 between adjacent connecting parts 11 is 1.005-1.05 times the distance D1 of the adjacent connecting parts 11, the length L2 of the bending part 12 does not exceed 1 / 2 of the welding strip length L1 between adjacent connecting parts 11, one bending part 12 includes one protrusion, the height H of which is 50-250μm, and the bending part 12 is preferably arranged in the middle between adjacent welding parts. The bending part is a curve or a trapezoidal shape, which is convenient for bending and shaping, and is also conducive to picking up the welding strip.

[0060] As a preferred technical solution, the spacing between adjacent connecting parts is 10-20 mm, the distance between the two ends of the bending part is 4-9 mm, and the height of the protrusion of the bending part is 100-200 μm. With this arrangement, there is a straight middle part 13 of a certain length (not less than 1 / 2) between the bending part 12 and the connecting part 11. This middle part 13 is adhered to the surface of the solar cell and remains stable, and is conducive to the adhesion of the connecting part 11 and the pad 21. The setting of the protrusion height is conducive to the stable placement of the welding strip on the surface of the solar cell, and can also adapt to the downward pressure of the flexible film on it. Even if the protrusion of the bending part 12 is skewed due to process problems, it will not overlap with the opposite grid line to cause a short circuit.

[0061] More preferably, as a preferred embodiment, the welding strip of the present invention has straight ends 14 at both ends of the welding strip. The straight setting of the ends 14 of the welding strip can avoid bending down and piercing the insulating glue and damaging the battery to cause hidden cracks during welding.

[0062] Those skilled in the art can understand that the welding strip extends in the length direction, and the bend 12 extends in the width direction of the entire welding strip. Ignoring the tiny and negligible thickness change caused by the stretching of the welding strip before cutting, the thickness of the entire welding strip is consistent. In other words, the bulge of the bend 12 is a bulge of a certain welding strip bending in the thickness direction, rather than a bulge caused by thickening of the thickness.

[0063] As a preferred embodiment, in order to achieve good contact between the connecting portion 11 and the pad 21, the soldering strip of the present invention has the connecting portion 11 as a concave portion in the opposite direction of the protrusion of the bending portion 12, and the depth of the concave portion is 20-50μm, preferably 20-40μm. It can be understood that the depth of the concave portion is adapted to the depth of the depression of the pad 21, and is usually equal to or slightly less than the depth of the pad 21. The distance between the two ends of the concave portion is roughly the same as the length of the pad, and preferably does not exceed the length of the pad.

[0064] Figure 7 The schematic diagram shows the connection of the welding ribbon between two battery cells.

[0065] It should be noted that the aforementioned protrusion height refers to the distance from the highest point to the middle part of the protrusion, and the depth of the recess refers to the distance from the lowest point to the middle part of the recess.

[0066] Furthermore, the applicant discovered during the research process that, during laser welding, although a bending portion is provided on the soldering ribbon to solve the warping problem of the battery cell, during actual cooling after laser processing, the shrinkage of the soldering ribbon between adjacent connection portions is not the same. Moreover, since the soldering ribbon is usually stored on a soldering ribbon roll, it has a certain curvature. Before the soldering ribbon is shaped, it is usually necessary to straighten the soldering ribbon, which will inevitably cause some expansion and contraction of the soldering ribbon during the subsequent welding process. As a result, when the warping measurement is performed, the warping data may show good results, but certain positions of the battery cell still receive tensile stress from the soldering ribbon, resulting in the risk of hidden cracks.

[0067] Therefore, in the welding strip provided by the present invention, preferably, the ratio of the length of the welding strip to the distance between the adjacent connecting parts at about the middle of the welding strip, about one-quarter of the welding strip, and three-quarters of the welding strip is greater than the ratio of the length of the welding strip to the distance between the adjacent connecting parts in the remaining parts. Usually, the adjacent connecting parts in the middle of the welding strip correspond to the welding points of the adjacent battery cells, and this position requires a large bending amount to avoid stretching the two battery cells to the middle after welding. The welding strip at about one-quarter and about three-quarters usually corresponds to the middle part of the battery cell, and this part also requires a large bending amount. This avoids hidden cracks in the battery.

[0068] On the other hand, the present invention also provides a method for welding a solar cell assembly, comprising the following steps:

[0069] Arrange the soldering ribbon and the battery cell one by one, make the connecting part of the soldering ribbon contact the soldering pad of the battery cell, and the bent part bulges upward relative to the solar cell, and weld the soldering ribbon to the soldering pad of the solar cell, wherein before arranging the soldering ribbon and the battery cell one by one, it also includes the step of shaping the soldering ribbon into the aforementioned soldering ribbon.

[0070] Specifically, the soldering ribbon is cut to a certain length as required, and then the soldering ribbon is shaped according to the aforementioned shape; or, the soldering ribbon is shaped according to the aforementioned shape, and then cut to a required length.

[0071] The soldering ribbon is usually stored in a roll, which causes the soldering ribbon to bend to a certain extent. Before cutting, the soldering ribbon needs to be straightened, which inevitably stretches the soldering ribbon, and this stretching will tend to shrink during the subsequent welding process. The soldering method of the present invention is more applicable to the above situation.

[0072] For example, if the length of the soldering ribbon after welding is 180mm, the soldering ribbon is straightened and then shaped and cut as required. Specifically, the soldering ribbon is stretched from a length of 176mm to 181mm, and then shaped according to the soldering point of the solar cell, and finally the distance between the two ends of the soldering ribbon is 180mm, the length of the soldering ribbon is 181mm, the distance between adjacent connecting parts is 14mm, there is an upwardly protruding curved part between adjacent connecting parts, the height of the curved part is 100μm, and the two ends are straight.

[0073] After welding, it was measured that the warpage of the solar cell 20 was 0-10.5 mm.

[0074] As a comparative example of the prior art, the length of the welding ribbon was extended from 176 mm to 180 mm, and the welding was performed directly without shaping. It was measured that the warping of the solar cell was 3 mm.

[0075] See also Figure 1 The warpage h is calculated based on the height difference between the two ends of the solar cell relative to the center.

[0076] It can be seen that the welding method of the present application greatly reduces the warping of the solar cell and can effectively solve the problem of hidden cracks in the cell.

[0077] Furthermore, the welding method of the solar cell assembly of the present invention further includes the step of preparing an insulating layer for the solar cell before arranging the welding ribbons and the solar cells one by one.

[0078] Furthermore, the welding method of the solar cell assembly of the present invention comprises the following steps:

[0079] S1 lays the solar cells and the welding ribbons on the solar cell back panel according to a preset pattern to obtain a solar cell module;

[0080] S2 places the solar cell assembly on a welding platform, covers the solar cell assembly of S2 with a flexible film, places the solar cell assembly in a closed space between the flexible film and the welding platform, and evacuates the closed space;

[0081] S3 irradiates the welding position by a laser beam arranged above the flexible film to complete the welding;

[0082] S4 removes the flexible film, covers the solar cell module with a packaging film and a cover plate, and laminates to obtain a solar cell module.

[0083] Furthermore, the aforementioned backplane includes a transparent base plate and a packaging film. Those skilled in the art may know that the transparent base plate may be photovoltaic glass, the cover plate may be photovoltaic glass, or a transparent plate of other materials, and the packaging film may be EVA, POE or other packaging films.

[0084] The solar cell may be a whole cell or a half cell.

[0085] On the other hand, the present invention also provides a solar cell assembly, which is prepared by the above method and includes a back plate, a packaging film, a welded solar cell sheet, a packaging film and a cover plate arranged in sequence from bottom to top.

[0086] Among them, the battery cell is a back-contact solar cell such as an IBC battery, and its upper surface is welded by the aforementioned welding strip using the aforementioned solar cell welding method.

[0087] Adjacent battery cells are connected by multiple parallel welding strips, and one welding strip connects two adjacent battery cells. The ratio of the welding strip length between the corresponding welding points between adjacent battery cells to the distance between adjacent welding points, and the ratio of the welding strip length between the adjacent welding points corresponding to the middle of the battery cell to the distance between adjacent welding points are greater than the ratios of the rest. For example, if there are 12 welding points on a welding strip, and there are 6 welding points on each battery cell, then the ratios between the 6th and 7th welding points, the 3rd and 4th welding points, and the 9th and 10th welding points are all greater than the ratios between the rest of the welding points. Figure 7 The corresponding bending parts are adaptively circled with dotted lines. Those skilled in the art can understand that when the number of welding points changes, the ratio between two or three adjacent welding points located in the middle of the battery cell and between adjacent battery cells can be set to be greater than the ratio between the remaining welding points.

[0088] Adjacent battery cells are connected by multiple parallel welding ribbons. When adjacent battery cells are connected by multiple parallel welding ribbons, the spacing between adjacent welding points is 10-20 mm, the length of the bending portion 12 is 4-9 mm, the bending portion 12 has a protrusion, the height of the protrusion is 50-250μm, and the bending portion 12 is located in the middle position of two adjacent connecting portions 11.

[0089] As an implementable solution, the length of the welding strip after welding is 180 mm, the number of welding points on a welding strip is 12, the spacing between adjacent welding points is 14-20 mm, the length of the welding strip before welding is 181 mm, the number of connecting parts 11 on a welding strip is 12, the spacing between adjacent welding points is 14-20 mm, the length of the bending part 12 is 6-7 mm, and the height of the protrusion is 100-200 μm. Preferably, the length of the welding strip before welding is stretched from 176 mm to 181 mm.

[0090] The solar cell assembly provided by the present invention has a solar cell with close to zero warping, or a warping degree far less than that of the solar cell assembly in the prior art. Those skilled in the art will understand that far less than means that the warping degree of the solar cell of the present invention is at least two orders of magnitude smaller than that of the prior art.

[0091] It should be noted that, in order to highlight the technical features of the present invention, all the drawings of the present invention, the curved parts and the concave parts are not drawn strictly according to the scale. Figure 1 , Figure 2 and Figure 4 In order to clearly represent the welding, the pad protrudes from the surface of the solar cell when drawing, and the middle part of the welding strip does not touch the surface of the solar cell. The actual setting of the pad should be based on the actual situation.

[0092] The above is only a preferred implementation of the present application. Although the present application has been disclosed as a preferred embodiment, it is not intended to limit the present application. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present application without departing from the scope of the technical solution of the present application, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the scope of protection of the technical solution of the present application.

Claims

1. A welding strip, Features: The welding strip comprises a connecting portion and a bending portion. In the length direction of the welding strip, a bending portion is arranged between every two adjacent connecting portions, and each bending portion comprises at least one protrusion.

2. A welding strip according to claim 1, Features: The connecting portion corresponds to the welding point of the solar cell.

3. A welding strip according to claim 1, Features: The curved portion is a curved protrusion or a trapezoidal protrusion.

4. A welding strip according to claim 1, Features: A straight middle portion is arranged between the bent portion and the connecting portion.

5. The welding strip according to claim 1, Features: The connecting portion is a concave portion in a direction opposite to the convex direction of the curved portion.

6. A welding strip according to claim 5, Features: The depth of the concave portion is 20-50 μm.

7. The welding strip according to claim 1, Features: The two ends of the welding strip are straight.

8. A welding strip according to any one of claims 1 to 7, Features: The length of the welding strip between adjacent connecting parts is 1.005-1.05 times the distance between the adjacent connecting parts.

9. A welding strip according to claim 8, Features: The height of the curved portion is 50-250 μm.

10. A welding strip according to claim 8, Features: The height of the curved portion is 100-200 μm.

11. A welding strip according to claim 8, Features: The distance between adjacent connecting parts is 10-20 mm.

12. A welding strip according to claim 8, Features: The distance between the two ends of the bending part is 4-9mm.

13. A welding strip according to claim 8, Features: The ratio of the length of the welding strip to the distance between adjacent connecting portions at approximately one quarter of the welding strip, three quarters of the welding strip and / or approximately the middle of the welding strip is greater than the ratio of the length of the welding strip to the distance between adjacent connecting portions in the remaining parts.

14. A method for welding a solar cell module, Features: The following steps are included: Arrange the soldering ribbon and the battery cell one by one, make the connecting part of the soldering ribbon correspond to the soldering pad of the solar cell, and the bent part bulges upward relative to the solar cell, and weld the soldering ribbon to the soldering pad of the solar cell. Before arranging the soldering ribbon and the battery cell one by one, it also includes shaping the soldering ribbon to obtain the soldering ribbon described in any one of claims 1 to 13.

15. A method for welding a solar cell assembly according to claim 14, Features: The welding strip connects two adjacent battery cells, wherein the ratio of the welding strip length between corresponding welding points between adjacent battery cells to the distance between adjacent welding points and / or the ratio of the welding strip length between adjacent welding points corresponding to the middle of the battery cell to the distance between adjacent welding points is greater than the ratio of the rest.

16. The method for welding a solar cell assembly according to claim 14, Features: The soldering ribbon is cut to a certain length as required, and then the soldering ribbon is shaped; or, the soldering ribbon is shaped and then cut to the required length.

17. The method for welding a solar cell assembly according to claim 14, Features: Before arranging the welding strips and the solar cells one by one, the method also includes the step of preparing an insulating layer for the solar cell cells.

18. A method for welding a solar cell assembly according to any one of claims 14 to 17, Features: The following steps are included: S1 lays the solar cells and the welding ribbons on the solar cell back panel according to a preset pattern to obtain a solar cell module; S2 places the solar cell assembly on a welding platform, covers the solar cell assembly of S2 with a flexible film, places the solar cell assembly in a closed space between the flexible film and the welding platform, and evacuates the closed space; S3 irradiates the welding position by a laser beam arranged above the flexible film to complete the welding; S4 removes the flexible film, covers the solar cell module with a packaging film and a transparent cover plate, and laminates to obtain a solar cell module.

19. The method for welding a solar cell assembly according to claim 18, Features: The back plate includes a transparent bottom plate and a packaging film.

20. A solar cell module, Features: The solar cell assembly is prepared by the welding method of any one of claims 14 to 19, wherein adjacent cells are connected by multiple parallel welding ribbons, one welding ribbon connects two adjacent cells, and before welding, the spacing between adjacent welding points on a welding ribbon is 10-20 mm, the distance between the two ends of the bending portion is 4-9 mm, the bending portion has at least one protrusion, the height of the protrusion is 50-250 μm, and the bending portion is located in the middle of two adjacent welding points; after welding, the welding ribbon between the welding points is in straight contact with the solar cell.

21. A solar cell assembly according to claim 20, Features: The ratio of the length of the solder strip between the corresponding solder joints between adjacent battery cells to the distance between adjacent solder joints and / or the ratio of the length of the solder strip between the adjacent solder joints corresponding to the middle of the battery cell to the distance between adjacent solder joints is greater than the ratio of the remaining parts.

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