Battery assembly and photovoltaic system

Abstract

The invention is suitable for the field of photovoltaic technology, and provides a battery assembly and a photovoltaic system. The conductive contact structure is arranged on the battery piece; the solar cell module comprises a cell, a conductive contact structure arranged on the cell, a welding strip arranged on the cell, the welding strip connected to the conductive contact structure, and at least one welding layer arranged between the conductive contact structure and the welding strip, the welding layer arranged between the conductive contact structure and the welding strip is arranged in a partitioned manner, the welding area is arranged between the conductive contact structure and the welding strip, and the welding area is arranged between the conductive contact structure and the welding strip. In addition, the welding layer further comprises a first area arranged outside one side of the welding strip and a second area arranged outside the other side of the welding strip, the deviation window of the welding strip is enlarged, the phenomena of insufficient welding and unsoldering of the welding strip are avoided, and the reliability of the assembly is improved.

Description

Technical Field

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

[0002] A photovoltaic (PV) cell is a thin film of photovoltaic semiconductors (also known as a solar cell or photovoltaic cell) that directly generates electricity using sunlight. As long as the illuminance meets certain conditions, it can output voltage and generate current when a circuit is present. Currently, crystalline silicon solar cells operating on the photovoltaic effect are the mainstream type of PV cell, which directly convert light energy into electrical energy through the photoelectric effect.

[0003] Multiple photovoltaic cells are interconnected to form a cell string. During the connection process, solder ribbons are used for connection. In the existing technology, solder paste is usually printed on the photovoltaic cells to achieve the soldering between the solder ribbon and the cell. However, this method can cause the solder ribbon to shift before soldering, which can easily lead to poor soldering after soldering, resulting in cold solder joints and affecting the reliability of the module. Summary of the Invention

[0004] This application provides a battery module designed to address the problem that in the prior art, solder paste is typically printed on a single point on the photovoltaic cell to achieve soldering between the solder strip and the cell. However, this method can lead to solder strip misalignment before soldering, which can easily result in poor soldering, incomplete soldering, and affect the reliability of the module.

[0005] This application is implemented as follows: a battery assembly includes: a battery cell; a conductive contact structure disposed on the battery cell; a solder strip disposed on the battery cell, the solder strip being connected to the conductive contact structure; at least one welding layer disposed between the conductive contact structure and the solder strip, the welding layer having at least a welding area disposed between the conductive contact structure and the solder strip, a first area disposed on one side of the solder strip, and a second area disposed on the other side of the solder strip, the area of ​​the welding area being larger than the area of ​​the first area, and / or the area of ​​the welding area being larger than the area of ​​the second area.

[0006] Optionally, the area of ​​the first region is larger than the area of ​​the second region.

[0007] Optionally, the weld layer has a first morphological structure in the first region, and the weld layer has a second morphological structure in the region, wherein the first morphological structure and the second morphological structure are different.

[0008] Optionally, the width of the first morphological structure is greater than the width of the second morphological structure. Optionally, in the width direction of the solder strip, the maximum width of the weld layer is a first width, which is greater than the width of the solder strip.

[0009] Optionally, the welding strip has a first central axis in the width direction, and the welding layer has a maximum length at the first central axis along the extension direction of the welding strip.

[0010] Optionally, the welding layer includes a first welding sublayer and a second welding sublayer, wherein the first welding sublayer and the second welding sublayer are arranged adjacent to each other in the length direction of the welding strip.

[0011] Optionally, in the width direction of the weld strip, the length of the first weld sublayer is greater than the length of the second weld sublayer.

[0012] Optionally, in the width direction of the solder strip, the length of the first weld sublayer is greater than the width of the solder strip.

[0013] Optionally, in the width direction of the solder strip, the length of the second solder sublayer is greater than the width of the solder strip, or the length of the second solder sublayer is less than the width of the solder strip, or the length of the second solder sublayer is equal to the width of the solder strip.

[0014] Optionally, the first welding sublayer and the second welding sublayer are spaced apart, or the first welding sublayer and the second welding sublayer are overlapped.

[0015] Optionally, the first welding sublayer and the second welding sublayer are at least partially connected, and the first welding sublayer and the second welding sublayer enclose a gap or hollow structure.

[0016] This application partitions the welding layer between the conductive contact structure and the solder strip. The welding area is located between the conductive contact structure and the solder strip to ensure the welding effect between the solder strip and the conductive contact structure and to achieve high welding strength. In addition, the welding layer also includes a first area located outside one side of the solder strip and a second area located outside the other side of the solder strip, which increases the offset window of the solder strip and avoids the phenomenon of poor soldering and desoldering of the solder strip, thereby improving the reliability of the module. Furthermore, the area of ​​the solder strip area is larger than the area of ​​either the first area or the area of ​​the second area, which effectively reduces the amount of slurry used in the welding layer while ensuring a firm weld between the solder strip and the cell, thereby reducing the manufacturing cost of the battery module. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the connection between the welding layer and the welding strip of the first type of battery module provided in the current application; Figure 2 This is a schematic diagram of the connection between the welding layer and the welding strip of the second type of battery module provided in the current application; Figure 3 This is a schematic diagram of the connection between the welding layer and the welding strip of the third type of battery module provided in the current application; Figure 4 This is a schematic diagram of the connection between the welding layer and the welding strip of the fourth type of battery module provided in the current application; Figure 5 This is a structural diagram of the first type of battery module provided in the current application before the welding layer is welded; Figure 6 This is a structural diagram of the second type of battery module provided in the current application before the welding layer is welded; Figure 7 This is a structural diagram of the third type of battery module provided in the current application before welding of the welding layer; Figure 8 This is a schematic diagram of the structure of the battery cells in the battery module provided in the current application.

[0018] Explanation of reference numerals in the attached figures: 100. Battery cell; 200. Conductive contact structure; 300. Welding strip; 400. Welding layer; 401. Welding area; 402. First area; 403. Second area; 404. First welding sublayer; 405. Second welding sublayer; 406. Notch; 407. Hollow structure. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0020] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0025] like Figure 8 As shown in the embodiments of this application, a battery assembly includes a battery cell 100, a conductive contact structure 200 disposed on the battery cell 100, and a solder ribbon 300 disposed on the battery cell 100, the solder ribbon 300 being connected to the conductive contact structure 200. The battery cell 100 can be a back contact battery, such as an IBC battery; it can also be other battery types, such as PERC batteries, HJT batteries, or TOPCon batteries, etc., and this application does not limit this.

[0026] Generally, the solar cell 100 has a sheet-like structure. The side that absorbs light energy and converts it into electrical energy is called the light-absorbing side or front side, and the other side is called the back side. The front and back sides of the solar cell 100 are arranged opposite each other. In this application, applicable to different types of solar cells 100, the conductive contact structure 200 can be disposed on the front and / or back sides of the solar cell 100. For example, in a back-contact solar cell 100, the conductive contact structure 200 is disposed on the back side of the solar cell 100. In a TOPCon battery, the conductive contact structure 200 can be disposed on both the front and back sides of the solar cell 100.

[0027] The conductive contact structure 200 is a metallized structure disposed on the surface of the solar cell 100, and may be formed, for example, by silver paste printing. In some embodiments, such as in PERC / TOPCon cells, the conductive contact structure 200 may be the main grid itself disposed on the solar cell 100 or a widened portion of its end. In some embodiments, such as in HJT cells, the conductive contact structure 200 may be a metal electrode block printed on a TCO film. In other embodiments, such as in back-contact cells, the conductive contact structure may be an independent, dot-like or small-block metallized region forming a pad structure, the shape of which may be, for example, rectangular or circular.

[0028] The conductive contact structure 200 serves as a welding point for welding with the solder ribbon 300. During subsequent welding of the solder ribbon 300, the conductive contact structure 200 can act as a welding point, reducing the use of welding paste, increasing the welding tensile strength in the edge area of ​​the solar cell 100, and improving the reliability of the solar module. Simultaneously, the conductive contact structure 200 can also serve as a testing point for the solar cell 100, for example, for hot spot and EL (electroluminescence) testing. The conductive contact structure 200 can be used to form stable contact with the test probes of testing equipment to test the electrical performance of the solar cell 100.

[0029] In traditional design schemes, solder paste is usually printed on photovoltaic cells to achieve soldering between the solder ribbon 300 and the cell 100. If the solder ribbon 300 is misaligned before soldering, it is easy to cause poor soldering after soldering, resulting in cold solder joints and affecting the reliability of the module.

[0030] like Figure 1As shown in the embodiments of this application, at least one solder layer 400 is provided between the conductive contact structure 200 and the solder ribbon 300. In this application, the solder layer 400 includes a solder structure formed by laminating solder paste printed on the battery cell 100 and then soldering it with the solder ribbon 300. The solder layer 400 is used to realize the solder connection between the solder ribbon 300 and the battery cell 100. The solder layer 400 has at least a soldering region 401 disposed between the conductive contact structure 200 and the solder ribbon 300, a first region 402 disposed on one side of the solder ribbon 300, and a second region 403 disposed on the other side of the solder ribbon 300. The area of ​​the soldering region 401 is larger than the area of ​​the first region 402, and / or, the area of ​​the soldering region 401 is larger than the area of ​​the second region 403. In this application, the solder layer 400 can be formed by laminating solder paste pre-printed on the battery cell 100 with solder ribbon 300. The solder layer 400 includes at least a soldering area 401. The solder ribbon 300 and the battery cell 100 are connected by soldering through the soldering area. The solder layer 400 also includes a first area 402 disposed on one side of the solder ribbon 300 and a second area 403 disposed on the other side of the solder ribbon 300. The first area 402 and the second area 403 serve as redundant areas of the solder layer 400 on the battery cell 100, so that even if the solder ribbon 300 is offset from the battery cell 100, effective soldering between the solder ribbon 300 and the battery cell 100 can still be guaranteed, avoiding poor soldering between the solder ribbon 300 and the battery cell 100. The welding area 401 serves as the main part of the welding process, and is designed to be a larger area. The first area 402 and the second area 403 serve as redundant areas, and are designed to be smaller areas. Specifically, the area of ​​the welding area 401 is larger than the area of ​​the first area 402 or the area of ​​the second area 403. This ensures the welding effect with the battery cell 100 and provides a given redundant area for the solder ribbon 300, while minimizing the use of solder paste. Preferably, the area of ​​the first area 402 is larger than the area of ​​the second area 403. That is, the redundant areas of the solder layer 400 on both sides of the solder ribbon 300 are designed to be unequal. This effectively reduces the alignment accuracy between the solder ribbon 300 and the welding layer 400, improving product yield. Furthermore, this design allows for a larger offset range on one side of the solder ribbon 300, ensuring sufficient material to guarantee a reliable connection even with significant deviations in the placement of the solder ribbon 300.

[0031] In some embodiments, the weld layer 400 has a first morphological structure in the first region 402 and a second morphological structure in the second region 403, and the first and second morphological structures are different. That is, the weld layer 400 has different appearance shapes in the first region 402 and the second region 403. In addition, the weld layer 400 also has different characteristics in other aspects. For example, the weld layer 400 has a rough surface in the first region 402 and a relatively smooth surface in the second region 403; or, the weld layer 400 has irregular edges in the first region 402 and relatively regular edges in the second region 403.

[0032] Furthermore, the width of the first morphological structure is greater than the width of the second morphological structure. Specifically, in the length direction of the solder strip 300, the size of the first morphological structure is greater than the size of the second morphological structure, and the wider first morphological structure can achieve a more secure connection between the solder layer 400 and the battery cell 100.

[0033] In the width direction of the solder strip 300, the maximum width of the welding layer 400 is a first width, which is greater than the width of the solder strip 300. This ensures that an additional material filling and connection area is formed outside the two side edges of the solder strip 300. This area serves as a redundant connection area between the solder strip 300 and the welding layer 400, increasing the offset window of the solder strip 300, avoiding incomplete soldering or desoldering of the solder strip 300, and improving the reliability of the module. Furthermore, as the connection structure between the solder strip 300 and the conductive contact structure 200, the welding layer 400, being wider than the solder strip 300, allows for a larger contact area between the welding layer 400 and the conductive contact structure 200 than the contact area between the solder strip 300 and the welding layer 400. This improves the connection strength between the solder strip 300 and the solar cell 100. In other embodiments, when the weld layer 400 forms rounded corners or protrusions on both sides of the weld strip 300, it actually forms a wrapping structure on the edge of the weld strip 300 in the vertical direction, which makes the weld strip 300 more difficult to peel or lift from the vertical or inclined direction.

[0034] Furthermore, when the weld layer 400 is wider, it forms a smooth stress transition zone from the weld strip 300 to the cell 100. The stress applied to the weld strip 300 can be more evenly distributed to the entire conductive contact structure 200 of the cell 100 through this wide weld layer 400, avoiding stress concentration in local areas.

[0035] like Figure 2As shown, in some embodiments, the solder strip 300 has a first central axis L in the width direction, and the weld layer 400 has its maximum length at the first central axis L along the extension direction of the solder strip 300. Specifically, the solder strip 300 is symmetrical about the first central axis L in the width direction, and the weld layer 400 has its maximum length at the position of the first central axis, ensuring that the thickest and strongest area of ​​the weld layer 400 is located at the center of the solder strip 300, thereby ensuring the effective welding area of ​​the solder strip 300.

[0036] like Figure 5 , Figure 6 and Figure 7 As shown, in some embodiments, the solder layer 400 includes a first solder sublayer 404 and a second solder sublayer 405, which are arranged adjacent to each other along the length of the solder strip 300. In this application, the solder layer 400 is segmented along the length of the solder strip 300, breaking away from the traditional design approach of treating the solder layer 400 as a single homogeneous material. Instead, it is segmented along its length, allowing different characteristics to be assigned to different segments of the solder layer 400, thus achieving flexible design. For example, the first solder sublayer 404 can use a material with better conductivity (such as high-silver-content paste or pure tin solder) to minimize resistance in the current transmission path and reduce power loss, while the second solder sublayer 405 can use a low-silver-content paste material to control costs, improve compatibility with the solder strip 300, and form a stronger solder joint, thereby enhancing the overall performance of the solder layer 400.

[0037] In some embodiments, the length of the first welding sublayer 404 is greater than the length of the second welding sublayer 405 in the width direction of the welding strip 300. Specifically, the size of the first welding sublayer 404 is greater than the size of the second welding sublayer 405 in the width direction of the welding strip 300. This differentiated design of the lengths of the first and second welding sublayers 404 and 405 allows for a more diversified structural configuration of the welding layer 400. Different welding sublayers can perform different main functions, which can save on the amount of slurry used in the welding layer 400 and reduce costs. For example, the first welding sublayer 404 can not only achieve the connection between the welding strip 300 and the battery cell 100, but also provide redundant portions on both sides of the welding strip 300. The second welding sublayer 405 is only used to achieve the welding connection between the welding strip 300 and the battery cell 100. Understandably, the length of the first welding sublayer 404 is greater than the width of the welding strip 300. This not only releases stress in the width direction of the welding strip 300, but also provides additional anchoring force on both sides of the welding strip 300 to prevent the ends of the welding strip 300 from lifting. Furthermore, in some embodiments, the length of the second welding sublayer 405 is greater than the width of the solder strip 300 in the width direction. This allows the second welding sublayer 405 to work synergistically with the first welding sublayer 404, effectively reinforcing the edges of the solder strip 300 and filling and wrapping the edge portion, reducing the path of moisture, oxygen, or other corrosive media into the interface between the solder strip 300, the welding layer 400, and the solar cell 100. In addition, designing the welding layer 400 to be wider than the solder strip 300 provides a safety margin for the alignment accuracy of the solder strip 300. Even if the solder strip 300 is slightly offset, as long as it still falls within the wider area of ​​the welding layer 400, the effective connection area is guaranteed, thereby improving production yield and process efficiency. In some embodiments, the length of the second welding sublayer 405 is less than the width of the welding strip 300 in the width direction. The second welding sublayer 405 serves only as a connection point between the welding strip 300 and the battery cell 100, minimizing the amount of slurry used in the welding layer 400 and achieving maximum cost reduction. In some embodiments, the length of the second welding sublayer 405 is equal to the width of the welding strip 300 in the width direction. This reduces the overall material usage of the welding layer 400 without affecting its main function, thereby lowering costs. At the same time, it ensures the welding reliability between the welding strip 300 and the battery cell 100, resulting in good long-term stability.

[0038] In some embodiments, the first welding sublayer 404 and the second welding sublayer 405 are spaced apart and discretely distributed, enabling the formation of independent welding points along the length of the welding strip 300, thereby strengthening the connection between the welding strip 300 and the battery cell 100. Furthermore, the gap between the first welding sublayer 404 and the second welding sublayer 405 can serve as a small heat dissipation channel, helping to dissipate heat generated at the welding point during operation (such as hot spot effects) more evenly and avoiding localized overheating. In addition, during welding or curing, the gap provides an escape path for volatile organic compounds or residual flux, helping to reduce the generation of bubbles and voids, forming a denser and more reliable connection interface.

[0039] In other embodiments, the first welding sublayer 404 and the second welding sublayer 405 are overlapped. That is, the two welding sublayers partially or completely overlap along the length of the solder strip 300, forming a continuous welding interface and creating a stable welding point between the solder strip 300 and the battery cell 100. Exemplarily, in the overlapping area, the two welding sublayers of different materials permeate and fuse with each other, forming a transition zone with continuously and gradually changing mechanical properties, allowing stress and strain to be smoothly transferred and dispersed, greatly reducing the risk of delamination at the interface. In other embodiments, the first welding sublayer 404 (such as copper-containing filler) is low in cost but prone to oxidation, while the second welding sublayer 405 (such as silver paste) has good oxidation resistance but is expensive. By having the second welding sublayer 405 welded to the solder strip 300 as the surface layer, while its bottom overlaps with the first welding sublayer 404, the low cost and high conductivity of the first welding sublayer 404 are utilized, while the excellent weldability and resistance to environmental aging of the second welding sublayer 405 are obtained. It achieves comprehensive performance that a single structure cannot simultaneously possess, finding the optimal balance between cost, performance, and reliability.

[0040] like Figure 3 and Figure 4 As shown, in some embodiments, the first welding sublayer 404 and the second welding sublayer 405 are at least partially connected, and the first welding sublayer 404 and the second welding sublayer 405 enclose a notch 406 or a hollow structure 407. That is, a portion of the first welding sublayer 404 and the second welding sublayer 405 are fused together, while another portion is spaced apart, forming a notch 406 or a hollow area between the first welding sublayer 404 and the second welding sublayer 405. Through this special structural design, the notch 406 or the hollow area becomes a natural stress concentration point. By pre-designing these structures in non-critical locations, without affecting the welding effect of the welding strip 300 and the battery cell 100, destructive stress can be actively guided to these pre-designed areas and released there through minor plastic deformation or deformation.

[0041] A photovoltaic system includes the aforementioned battery modules. In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants, and can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0042] In the description of this specification, the use of terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., refers to specific features, structures, materials, or characteristics described in connection with the embodiments or examples, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery assembly characterized by, The battery assembly comprises: a battery piece; a conductive contact structure arranged on the battery piece; a solder strip arranged on the battery piece, the solder strip being connected to the conductive contact structure, at least one solder layer arranged between the conductive contact structure and the solder strip, the solder layer having at least a soldering area arranged between the conductive contact structure and the solder strip, a first area arranged on one side of the solder strip, and a second area arranged on the other side of the solder strip, the area of the soldering area being greater than the area of the first area, and / or the area of the soldering area being greater than the area of the second area.

2. The battery assembly of claim 1, wherein, The area of the first area is greater than the area of the second area.

3. The battery assembly of claim 1, wherein, The solder layer has a first topography structure in the first area, and a second topography structure in the second area, the first topography structure being different from the second topography structure.

4. The battery assembly of claim 2, wherein, The width of the first topography structure is greater than the width of the second topography structure.

5. The battery assembly of claim 1, wherein, In the width direction of the solder strip, the maximum width of the solder layer is a first width, the first width being greater than the width of the solder strip.

6. The battery assembly of claim 1, wherein, The solder strip has a first central axis in the width direction, and along the extension direction of the solder strip, the solder layer has a maximum length at the first central axis.

7. The battery assembly of claim 1, wherein, The solder layer comprises a first solder sub-layer and a second solder sub-layer, the first solder sub-layer and the second solder sub-layer being arranged adjacent to each other in the length direction of the solder strip.

8. The battery assembly of claim 7, wherein, In the width direction of the solder strip, the length of the first solder sub-layer is greater than the length of the second solder sub-layer.

9. The battery assembly of claim 7, wherein, In the width direction of the solder strip, the length of the first solder sub-layer is greater than the width of the solder strip.

10. The battery assembly of claim 7, wherein, In the width direction of the solder strip, the length of the second solder sub-layer is greater than the width of the solder strip, or the length of the second solder sub-layer is less than the width of the solder strip, or the length of the second solder sub-layer is equal to the width of the solder strip.

11. The battery assembly of claim 7, wherein, The first solder sub-layer and the second solder sub-layer are arranged in a spaced manner, or the first solder sub-layer and the second solder sub-layer are arranged in an overlapping manner.

12. The battery assembly of claim 7, wherein, The first solder sub-layer and the second solder sub-layer are at least partially connected, and the first solder sub-layer and the second solder sub-layer enclose a notch or a hollow structure.

13. A photovoltaic system characterized by, The battery assembly comprises any one of the battery assemblies according to claims 1-12.

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