Photovoltaic module

Abstract

The application relates to the technical field of solar cells, and provides a photovoltaic module. The photovoltaic module comprises a plurality of cell string groups and a plurality of bus bars. The cell string group comprises at least two cell strings arranged along a first direction, each cell string is composed of a plurality of cell pieces connected in series, the first surface of each cell piece is provided with a plurality of welding points, the plurality of cell string groups are arranged along a second direction, and the first direction intersects the second direction. The bus bar is located on the first surface of the cell piece, and the bus bar is electrically connected with the welding point. The plurality of bus bars comprises a first bus bar. In the second direction, the first bus bar is arranged at the two ends of the cell string group along the first direction. The application solves the problems that the welding process of the bus bar and the welding strip is complex and the risk of hidden cracks is high in the prior art.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a photovoltaic module. Background Technology

[0002] Currently, photovoltaic modules adopt a structure in which independent solder strips and busbars are welded in stages. This requires precision tooling to adsorb and transport the solder strips, which is prone to incomplete welding and misalignment due to solder strip deformation. The process is complex and the yield is low. In addition, the height difference formed by the superposition of busbars and solder strips can easily cause microcracks and cell breakage risks after lamination.

[0003] Existing solutions still rely on additional solder strips or complex processes, failing to truly achieve direct electrical connection and structural integration between the busbar and the battery cell, and also carrying a high risk of microcracks. Summary of the Invention

[0004] This application provides a photovoltaic module that at least helps to improve the problem of complex welding processes and high risk of microcracks in the busbar and solder strip welding process.

[0005] According to some embodiments of this application, one aspect of this application provides a photovoltaic module, including multiple battery string groups, each battery string group including at least two battery strings arranged along a first direction, each battery string being composed of multiple battery cells connected in series, each battery cell having multiple solder points on its first surface, the multiple battery string groups being arranged along a second direction, the first direction intersecting the second direction; multiple busbars, the busbars being located on the first surface of the battery cells and electrically connected to the solder points, the multiple busbars including a first busbar, in the second direction, the first busbar being disposed at both ends of the battery string group along the first direction.

[0006] In some embodiments, the plurality of busbars includes a second busbar disposed in the middle of the battery string along the first direction in the second direction.

[0007] In some embodiments, the busbar is welded to the solder joint by a plurality of first solder strips, the plurality of first solder strips being arranged along the second direction on a first surface of the busbar, and the width of the first solder strips in the first direction being equal to the width of the busbar in the first direction.

[0008] In some embodiments, in the second direction, each of the busbars is in direct contact with the solder joint.

[0009] In some embodiments, the photovoltaic module further includes insulating film strips, a plurality of the insulating film strips being arranged along the second direction on a first surface of the busbar, and the insulating film strips being located between adjacent first solder strips.

[0010] In some embodiments, in the first direction, adjacent solar cells are connected to the solder joints via a second solder strip.

[0011] In some embodiments, the thickness of the second solder strip is equal to the thickness of the busbar, and the difference between the thickness of the second solder strip and the thickness of the first solder strip is ≤0.05mm.

[0012] In some embodiments, the first welding strip is a round wire welding strip or a flat welding strip.

[0013] In some embodiments, the busbar is locally widened in the area in contact with the solder joint, and the width of the widened portion in the first direction is 1.2 to 2.0 times the diameter of the solder joint.

[0014] In some embodiments, a first region on the first side of the battery cell has two columns of solder joints along the second direction, and a second region on the first side of the battery cell has two columns of solder joints along the second direction. Each column of solder joints is spaced apart along the second direction. Two columns of solder joints in the same region are electrically connected by metal leads, and two adjacent columns of solder joints in different regions are connected by a third solder strip.

[0015] According to the technical solution of this application, a photovoltaic module includes multiple cell string groups and multiple busbars. Each cell string group includes at least two cell strings arranged along a first direction. Each cell string is composed of multiple cells connected in series. Each cell has multiple solder points on its first surface. The multiple cell string groups are arranged along a second direction, where the first and second directions intersect. The busbars are located on the first surface of the cell and are electrically connected to the solder points. The multiple busbars include a first busbar, which is positioned at both ends of the cell string group along the first direction in the second direction. In this application, by setting solder points on the cell and welding the busbars to the solder points of the cell, the busbars and cell are integrated. This eliminates the need for complex tooling to pick up and place the solder strips and busbars; simply picking up the busbars and placing them is sufficient. This solves the problems of complex welding processes and high risk of microcracks in the prior art for busbars and solder strips. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of a photovoltaic module according to an embodiment of this application is shown;

[0018] Figure 2 A schematic diagram of the busbar and solder joint connection of a specific photovoltaic module according to an embodiment of this application is shown;

[0019] Figure 3 A schematic diagram of a solar cell for a specific photovoltaic module according to an embodiment of this application is shown;

[0020] Figure 4 A schematic diagram of the current transmission path of a specific photovoltaic module according to an embodiment of this application is shown;

[0021] Figure 5 A schematic diagram showing the layout of the cells of a specific photovoltaic module according to an embodiment of this application is provided;

[0022] Figure 6 A schematic diagram of the insulating film strip arrangement of a specific photovoltaic module according to an embodiment of this application is shown;

[0023] Figure 7 A schematic diagram of a specific photovoltaic module provided according to an embodiment of this application is shown;

[0024] Figure 8 A schematic diagram of a widened busbar for a specific photovoltaic module according to an embodiment of this application is shown;

[0025] Figure 9 A schematic diagram of a non-circular busbar for a specific photovoltaic module provided according to an embodiment of this application is shown.

[0026] The above figures include the following reference numerals:

[0027] 01. Photovoltaic module; 10. Battery string; 11. Battery string; 110. Battery cell; 1110. Solder joint; 20. Busbar; 201. First busbar; 202. Second busbar; 30. First solder strip; 1101. First area; 1102. Second area; 40. Metal lead; 50. Third solder strip; 60. Insulating film tape. Detailed Implementation

[0028] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0031] As described in the background section, in the prior art, photovoltaic modules adopt a structure in which independent solder strips and busbars are welded in stages. This relies on additional solder strips or complex processes, which fails to truly achieve direct electrical connection and structural integration between the busbars and the cells, and also carries a high risk of microcracks. To solve the above problems, the embodiments of this application provide a photovoltaic module.

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0033] This application provides a photovoltaic module, such as... Figure 1 As shown, the photovoltaic module 01 mentioned above includes:

[0034] Multiple battery string groups 10, each battery string group 10 including at least two battery strings 11 arranged along a first direction, each battery string being composed of multiple battery cells 110 connected in series by a welding process. The first surface of each battery cell 110 is provided with multiple solder points 1110 by screen printing and low-temperature sintering. The solder points are formed by printing silver-containing conductive paste, and their morphology is precisely shaped by high-resolution screen design and cured by infrared fast-burning furnace or microwave-assisted sintering to ensure that the solder points are highly consistent and free of cracks or oxidation, providing a clean, uniform, and highly solderable metal contact interface for subsequent busbar welding. The multiple battery string groups 10 are arranged along a second direction, and high alignment accuracy is achieved by a high-precision visual positioning system and an automatic pick-and-place device to ensure that the ends of each string group are flush, providing a stable and flat welding reference surface for subsequent busbar welding. The first direction and the second direction intersect.

[0035] Multiple busbars 20 are located on the first side of the battery cell 110 and are electrically connected to the solder joint 1110 by direct welding or indirect welding via the first solder strip. The multiple busbars 20 include a first busbar 201. In the second direction, the first busbar 201 is disposed at both ends of the battery string 10 along the first direction. Its positioning and welding are completed by high-precision automatic mounting equipment and hot air or laser welding process.

[0036] In the above embodiments, the busbar is placed on the first side of the battery cell (i.e., the back side of the battery cell) and electrically connected to the solder joints on the back side. First busbars are arranged at both ends of the battery string along the first direction. This design eliminates the traditional process of pre-welding the solder strip and busbar with complex adsorption fixtures. Whether the busbar is directly welded to the solder joint or indirectly connected via independent solder strips, its physical location is always in the solder joint area on the back of the battery cell, ensuring a current path. This structure eliminates front solder strip obstruction, achieving a full-screen appearance. Furthermore, because the busbars are located at both ends, it avoids abrupt changes in the lamination thickness in the middle area, reducing the risk of microcracks. In terms of process, only a conventional suction nozzle is needed to pick up the busbar to complete the mounting, eliminating the need for complex composite fixtures.

[0037] Through the above embodiments, solder joints are set on the battery cell, and the busbar is welded to the solder joints of the battery cell, realizing the integrated integration of the busbar and the battery cell. It is not necessary to use complex tooling to pick up and place the solder strip and the busbar. It is only necessary to pick up the busbar normally and place it. This solves the problem of complex welding process and high risk of hidden cracks in the prior art of busbar and solder strip welding.

[0038] In some embodiments of this application, such as Figure 1 As shown, the plurality of busbars 20 include a second busbar 202, which is disposed in the middle of the battery string 10 along the first direction in the second direction.

[0039] In the above embodiments, a second busbar is positioned at the lateral middle of the battery string. This design, without altering the structure where the busbar is located on the back of the battery cell and electrically connected to the solder joint, effectively shortens the current transmission path, reduces series resistance, and improves the module's power output by placing a middle busbar in the long battery string. The second busbar can also be directly welded or connected via solder strips. The busbar is positioned at both ends and in the middle of the battery string, and is electrically connected by direct welding to the solder joints on the back of the battery cell. Its thickness perfectly matches the solder joint area, and there are no local thickness abrupt changes or protrusions after lamination. Therefore, the introduction of the second busbar does not generate additional stress concentration, does not increase the risk of microcracks, and improves electrical performance due to the shortened current path.

[0040] Through the above embodiments, by setting a second busbar in the middle of the battery string, the current transmission path is shortened and the series resistance is effectively reduced. At the same time, since the second busbar uses the same process, the same thickness, and is mounted on the same plane as the first busbar, no thickness change or mechanical stress concentration is introduced. This achieves the optimization of electrical performance while ensuring reliability, and achieves the technical effect of high power and low microcracks.

[0041] In some embodiments of this application, such as Figure 2 As shown, the busbar 20 is welded to the weld point 1110 by a plurality of first weld strips 30. The plurality of first weld strips 30 are arranged along the second direction on the first surface of each busbar 20, and the width of each first weld strip 30 in the first direction is equal to the width of each busbar 20 in the first direction.

[0042] In the above embodiments, the busbar is connected to the solder joints via multiple first solder strips, and these solder strips are arranged along the second direction on the first surface of the busbar. Their width in the first direction is equal to the width of the busbar in the first direction, and these strips should be considered substantially identical within the measurement tolerance or manufacturing error range. This design abandons the traditional method of overlapping narrow solder strips, instead adopting a structure with equal width and full coverage, ensuring that each solder strip precisely covers the entire width of the busbar in the first direction.

[0043] Through the above embodiments, this structure not only eliminates the risks of poor soldering, desoldering and stress concentration caused by excessively narrow solder strips, but also ensures that the surface of the component remains highly flat after lamination because the solder strip is flush with the edge of the busbar. This avoids the hidden crack risks caused by exposed solder strips or protruding busbars in traditional solutions, thereby improving welding reliability and product yield.

[0044] In some embodiments of this application, in the first direction, adjacent battery cells are connected to the solder joints via a second solder strip.

[0045] In some embodiments of this application, such as Figure 3 As shown, the first region 1101 of the first surface of the battery cell 110 has two rows of solder joints 1110 along the second direction, and the second region 1102 of the first surface of the battery cell 110 has two rows of solder joints 1110 along the second direction. Each row of solder joints 1110 is spaced apart along the second direction. The two rows of solder joints 1110 on the same side are electrically connected by metal leads 40, and the two adjacent rows of solder joints 1110 on different side are connected by a third solder strip 50.

[0046] By setting two rows of solder joints in each of the two regions of the battery cell and achieving lateral parallel conduction within the regions with metal leads, and then connecting the outer rows of solder joints in different regions with a third solder strip, the current density and series resistance of a single row of solder joints are reduced, and the current collection efficiency and resistance to microcracks are improved. This structure achieves a more uniform current distribution and lower power loss.

[0047] In this application, busbars are positioned at both ends or in the middle of the battery string along the first direction. Battery cells not connected by busbars are then connected to solder joints via second solder strips to achieve current transfer between cells. Specifically, before structural design, internal electrical performance connections must be designed within the battery cells to ensure the electrical performance transfer path is: solder joint → solder strip → solder joint → solder joint → solder strip, such as... Figure 4 As shown, the current transmission from the leftmost side is: solder strip → solder joint → solder joint → solder strip → solder joint → solder joint → solder strip. Specifically, the solar cell has several solder strips and solder joints 1110. Adjacent solder joints on the same side are electrically connected by metal leads 40 (connecting wires between solder joints). The current is introduced from the left solder strip (i.e., the second solder strip), transmitted through the solder strip to the first solder joint connected to it, and then transmitted through the metal lead 40 to the adjacent second solder joint; subsequently, it is connected to the third solder strip 50 connected to the second solder joint and continues to be transmitted to the third solder joint, and then transmitted through the metal lead 40 to the fourth solder joint, finally merging into the right solder strip (i.e., the second solder strip) connected to the fourth solder joint and being led outward, forming a transmission path of solder strip → solder joint → solder joint → solder strip → solder joint → solder joint → solder strip, realizing the current transmission to the next solar cell, and the next solar cell repeats the same path.

[0048] According to such Figure 4 The battery stencil design and stringing method shown are illustrated. The final layout diagram can be found in [reference needed]. Figure 5 .

[0049] In the above embodiments, in the optional implementation where the busbars are located at both ends or in the middle of the battery string, current transmission between adjacent cells is achieved through welding with a second solder strip and solder joints. This structure avoids the stringent requirements for equipment precision and material consistency imposed by continuous welding of the entire busbar path. Simultaneously, combined with the current conduction design within the battery cells, it improves current collection efficiency and resistance to microcracks. In summary, this structure achieves reliable electrical connections between battery cells, ensuring smooth current transmission. Furthermore, the positioning welding at solder joints improves welding precision and consistency, reduces the risk of incomplete or faulty welds, and enhances the reliability and power output stability of the module.

[0050] In some embodiments of this application, the thickness of the second solder strip is equal to the thickness of the busbar, and the difference between the thickness of the second solder strip and the thickness of the first solder strip is ≤0.05mm.

[0051] In the above embodiments, the thickness of the second solder strip is consistent with the thickness of the busbar, while the thickness difference between the second solder joint and the first solder strip is controlled within the range of ≤0.05mm. This design aims to achieve planar collaborative bonding between the solder strip and the busbar during the lamination process, avoiding local bulges or stress concentration after lamination due to thickness differences. In the structure of this application, the first solder strip serves as the connection structure between the busbar and the cell solder joint, and its thickness must match that of the busbar to ensure a smooth welding surface. The second solder strip serves as the connector between adjacent cells; if its thickness is significantly greater than that of the busbar, it will cause a step or bulge to form at that location after lamination, increasing the risk of microcracks. If its thickness is much smaller than that of the first solder strip, it is prone to causing uneven contact resistance and abnormal current distribution.

[0052] Through the above embodiments, setting the thickness of the second solder strip to be consistent with the thickness of the busbar, and with a difference of ≤0.05mm from the thickness of the first solder strip, ensures a smooth overall laminated interface. The solder strip, busbar, and solder joint form a near-equal height structure in the thickness direction, eliminating mechanical stress caused by local thermal expansion differences. This design also stabilizes the welding tensile force, ensuring all solder joints are under similar thermodynamic environments, thus improving the reliability of electrical connections. This design achieves thickness coordination, interface flushness, and uniform stress distribution in the laminated structure, improving component yield and reliability.

[0053] In some embodiments of this application, such as Figure 6 As shown, the photovoltaic module also includes an insulating film strip 60, and a plurality of the insulating film strips 60 are arranged along the second direction on the first surface of each busbar 20, and each insulating film strip 60 is located between adjacent first solder strips 30.

[0054] In the above embodiments, in addition to the conductive structure formed by the busbar and solder strips, an insulating film strip is also provided, which serves to provide electrical isolation and mechanical protection for the busbar. Specifically, multiple insulating film strips are arranged along the second direction and attached to the first surface of the busbar, with the insulating film strips positioned in the gap area between two adjacent first solder strips. This design, by providing insulating film strips on the surface of the busbar, can prevent accidental short circuits between the busbar and the metallized areas (such as main grids or solder joints) of adjacent cells, providing reliable electrical isolation; it can also guide and fix the position of the busbar, preventing it from shifting during transportation, lamination, etc., thus improving manufacturing yield; moreover, in this design, the insulating film strip can serve as a load-bearing structure, allowing the busbar to be picked up, placed, and positioned without additional tooling, achieving efficient mounting. The arrangement of the insulating film strips is not arbitrary coverage, but corresponds to the intervals between the solder strips within the cell, ensuring that while achieving insulation, the direct contact area between the busbar and the solder joint is not obstructed, thereby maintaining the integrity of the current transmission path.

[0055] Through the above embodiments, multiple insulating film strips are arranged along the second direction on the first surface of the busbar, and the insulating film strips are placed between adjacent first solder strips, which effectively isolates the potential difference between the solder strips, prevents leakage and short circuit, and reduces the interface corrosion between the encapsulation material and the metal solder strip, thereby improving the electrical safety and long-term reliability of the photovoltaic module.

[0056] In some embodiments of this application, the first welding strip is a round wire welding strip or a flat welding strip.

[0057] In the above embodiments, the first welding strip is either a round wire welding strip or a flat welding strip. The round wire welding strip possesses good flexibility and weldability. When used as the first welding strip, its diameter matches the width of the busbar. By precisely controlling the welding temperature and pressure, a uniform, non-protruding, flat and closely fitting welding area is formed below the busbar, ensuring sufficient metallurgy at the weld contact surface and avoiding stress concentration or incomplete welds due to cross-sectional mismatch. The flat welding strip has a higher conductive cross-sectional area and mechanical strength. When used as the first welding strip, its thickness direction is aligned with the thickness direction of the busbar, and its width direction is consistent with the busbar, achieving surface-to-surface contact welding. This reduces contact resistance, improves current transmission efficiency, and reduces the risk of microcracks due to the absence of height abrupt changes.

[0058] Through the above embodiments, the first solder strip can be made of round wire or flat wire, achieving an equal-width bonding design that matches the width of the busbar, thereby improving welding reliability and current transmission efficiency. Round wire is suitable for low-temperature processes and reduces battery damage, while flat wire provides a higher conductive cross-section and stronger welding tensile strength, enhancing the applicability of this application to different battery technologies and production line conditions, and realizing high-performance, high-yield, and easy-to-mass-produce full-screen components.

[0059] Will as Figure 6 The structure shown is placed on the layout diagram. The cells are electrically connected to the solder strips through lamination, thus completing the fabrication of the entire module. Figure 7 As shown. Among them, Figure 7 (b) is Figure 7 (a) is an enlarged schematic diagram of busbar 20, which connects two battery strings 11. Figure 7 (b) The middle busbar 20 is Figure 6 The structure shown.

[0060] In some embodiments of this application, in the second direction described above, each of the busbars is in direct contact with the solder joint.

[0061] In the above embodiments, the busbar is no longer electrically connected to the cell's solder joints via any intermediate solder strips. Instead, it directly contacts the solder joints through welding, enabling current transmission from the busbar to the cell. There are no independent solder strip structures between the busbar and the solder joints; they are in direct contact through welding. The busbar itself performs the functions of current collection and transmission. This design solves the problems of process complexity and thickness accumulation caused by the presence of solder strips in existing technologies. Traditional solutions require special nozzles to adsorb and position the solder strip and busbar, which is prone to misalignment and incomplete welding. Furthermore, the superposition of solder strips and busbars leads to local bulges, resulting in a high risk of microcracks after lamination.

[0062] Through the above embodiments, the busbar is in direct contact with the solder joints, and the electrical connection between the busbar and multiple solder joints can be completed in just one welding action, eliminating the need for solder strip laying, alignment, welding and other processes; the thickness of the solder strip is eliminated, the overall thickness of the module after lamination is reduced, and stress concentration is reduced.

[0063] In some embodiments of this application, the busbar is locally widened in the area in contact with the solder joint, and the width of the widened portion in the first direction is 1.2 to 2.0 times the diameter of the solder joint.

[0064] In the above embodiments, to achieve reliable direct contact between the busbar and the solder joint, such as Figure 8 As shown, the busbar 20 is locally widened in the area contacting the solder joint 1110, with the width of the widened area in the first direction being 1.2 to 2.0 times the diameter of the solder joint. This design aims to solve the problems of difficult welding alignment, insufficient contact area, and low welding strength in the direct welding of the busbar to the solder joint. In the above embodiment where the busbar and the solder joint are in direct contact, if the width of the busbar is exactly the same as the diameter of the solder joint, the alignment tolerance at the welding position can easily lead to welding misalignment, incomplete contact, cold solder joint, or the solder joint not being completely covered, which in turn causes increased contact resistance, power attenuation, or even open circuit failure. If the busbar is too wide (>2.0 times the diameter of the solder joint), it will cover adjacent solder joints or the main grid area, causing short circuit risk or light shading loss, and damaging the effective light-receiving area of ​​the solar cell.

[0065] Through the above embodiments, the widened area can completely cover the solder joints, ensuring that most solder joints are effectively welded even with alignment deviations. The widened range does not extend into the distance between adjacent solder joints, ensuring no electrical interference between the main grid and adjacent solder joint areas. This width range matches the melting and diffusion area of ​​mass production processes such as laser welding and hot air welding, enabling single-shot welding and simultaneous fusion of multiple points, thus improving welding efficiency. In summary, by locally widening the busbar in the area in contact with the solder joint to 1.2 to 2.0 times the solder joint diameter, the technical effects of tolerance welding, full coverage, and no short circuits are achieved, contributing to improved manufacturing yield and ensuring mass production.

[0066] In some embodiments of this application, such as Figure 9 As shown, the busbar 20 can also be a non-standard busbar, where the welding area corresponding to the solder joint 1110 is widened separately, while the rest remains at a conventional width. This structure widens only the area directly above the solder joint that needs to be directly welded (e.g., the width is 1.2 to 2.0 times the diameter of the solder joint), while the remaining area has the same width as a traditional busbar, achieving precise welding, minimal obstruction, and overall fit. Furthermore, the non-standard structure allows for a smoother transition between the busbar and the cell surface after lamination, reducing the risk of microcracks.

[0067] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A photovoltaic module, characterized in that, include: Multiple battery string groups, each battery string group including at least two battery strings arranged along a first direction, each battery string being composed of multiple battery cells connected in series, each battery cell having multiple solder points on its first surface, the multiple battery string groups being arranged along a second direction, the first direction intersecting the second direction; Multiple busbars are located on the first side of the battery cell and are electrically connected to the solder joint. The multiple busbars include a first busbar, which is disposed at both ends of the battery string along the first direction in the second direction.

2. The photovoltaic module according to claim 1, characterized in that, The plurality of busbars includes a second busbar, which is disposed in the middle of the battery string along the first direction in the second direction.

3. The photovoltaic module according to claim 1, characterized in that, The busbar is welded to the weld point by a plurality of first weld strips, the plurality of first weld strips being arranged along the second direction on the first surface of the busbar, and the width of the first weld strips in the first direction being equal to the width of the busbar in the first direction.

4. The photovoltaic module according to claim 1, characterized in that, In the second direction, each of the busbars is in direct contact with the solder joint.

5. The photovoltaic module according to claim 3, characterized in that, The photovoltaic module also includes insulating film strips, a plurality of which are arranged along the second direction on the first surface of the busbar, and the insulating film strips are located between adjacent first solder strips.

6. The photovoltaic module according to claim 3, characterized in that, In the first direction, adjacent battery cells are connected to the solder joint by a second solder strip.

7. The photovoltaic module according to claim 6, characterized in that, The thickness of the second solder strip is equal to the thickness of the busbar, and the difference between the thickness of the second solder strip and the thickness of the first solder strip is ≤0.05mm.

8. The photovoltaic module according to claim 3, characterized in that, The first welding strip is a round wire welding strip or a flat welding strip.

9. The photovoltaic module according to claim 4, characterized in that, The busbar is locally widened in the area in contact with the solder joint, and the width of the widened portion in the first direction is 1.2 to 2.0 times the diameter of the solder joint.

10. The photovoltaic module according to claim 1, characterized in that, The first region of the first side of the battery cell has two columns of solder joints along the second direction, and the second region of the first side of the battery cell has two columns of solder joints along the second direction. Each column of solder joints is spaced apart along the second direction. The two columns of solder joints in the same region are electrically connected by metal leads, and the two adjacent columns of solder joints in different regions are connected by a third solder strip.

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