Back contact cell, cell assembly, and photovoltaic system

Abstract

The application is suitable for the field of photovoltaic technology, and provides a back contact cell, a cell module and a photovoltaic system. The back contact cell comprises a substrate, the substrate has a first surface and a second surface arranged oppositely, a first grid line structure and a second grid line structure are arranged at intervals on the first surface; a first busbar is arranged on the second surface, the first grid line structure is connected to the first busbar through the substrate at least partially, and the carrier on the back of the cell is connected to the front of the cell through the above structure design. The grid line structure on the first surface is connected to the busbar on the second surface through the substrate at least partially, the carrier on the back of the cell is connected to the front of the cell, the grid line structure on the first surface of one of the two adjacent cells is directly overlapped with the busbar on the second surface of the other cell to realize the interconnection between the adjacent cells, the solder strip is not needed, the moving distance of the carrier is shortened, the stringer equipment is saved, and the process production steps of the cell module are simplified.

Description

Technical Field

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

[0002] Solar cells, also known as photovoltaic cells, are devices that directly convert light energy into direct current (DC) using the photovoltaic effect. The PN junction on the semiconductor in a solar cell can directly convert solar energy into electrical energy through the photovoltaic effect. Solar cells are typically sheet-shaped. Solar cells with both electrodes of different polarities formed on the back of the cell are called back-contact cells. Currently, back-contact solar cells (such as IBC, MWT, and EWT solar cells) have received widespread attention. Because they have no grid lines or even any electrode patterns on the front side, with both the positive and negative electrodes located on the back of the cell, they reduce shading and effectively increase the short-circuit current, thus improving the energy conversion efficiency. However, existing back-contact solar cells have electrodes located on the back of the cell, requiring the use of solder ribbons for stringing. This prevents them from being directly stacked and connected to form a string like traditional crystalline silicon solar cells. Utility Model Content

[0003] This application provides a back-contact solar cell, which aims to solve the problem that the electrodes of existing back-contact solar cells are all located on the back of the cell, requiring the use of solder ribbons for stringing, and cannot be directly stacked and arranged to connect the positive and negative electrodes of adjacent cells to form a cell string, as is the case with traditional crystalline silicon solar cells.

[0004] This application is implemented as follows: a back-contact battery cell includes a substrate having a first surface and a second surface disposed opposite to each other, a first grid structure and a second grid structure spaced apart on the first surface; a first bus grid line disposed on the second surface, the first grid structure at least partially passing through the substrate and connected to the first bus grid line; and / or a second bus grid line disposed on the second surface, the second grid structure at least partially passing through the substrate and connected to the second bus grid line.

[0005] In this application, through the above-described structural design, the grid structure of the first surface is configured to partially pass through the substrate and connect with the busbars of the second surface, thereby drawing the charge carriers on the back of the cell to the front of the cell. In this way, the grid structure of the first surface of one of the two adjacent cells is directly connected to the busbars of the second surface of the other cell to achieve interconnection between the adjacent cells. No solder strip is required, which shortens the movement distance of the charge carriers, saves the investment in string bonding equipment, simplifies the process production steps of the battery module, and the overlapping interconnection between adjacent cells eliminates the gap between the cells, further improving the power density of the module.

[0006] Optionally, the first grid structure includes a plurality of first fine grids, which extend along the first direction and are spaced apart along the second direction, with at least a portion of the first fine grids passing through the substrate and connected to the first bus grid.

[0007] Optionally, the first gate structure includes a plurality of first fine gates and a first interconnect gate line connected to the plurality of first fine gates, wherein the first interconnect gate line at least partially passes through the substrate and is connected to the first bus gate line.

[0008] Optionally, the first interconnecting gate line includes a plurality of first sub-gate lines, with at least every two first fine gates correspondingly connected to one first sub-gate line, and each first sub-gate line at least partially passing through the substrate and connected to the first bus gate line.

[0009] Optionally, the second grid structure includes a plurality of second fine grids, which extend along the first direction and are spaced apart along the second direction, with at least a portion of the second fine grids passing through the substrate and connected to the second bus grid.

[0010] Optionally, the second gate structure includes a plurality of second fine gates and a second interconnect gate line connected to the plurality of second fine gates, wherein the second interconnect gate line at least partially passes through the substrate and is connected to the second bus gate line.

[0011] Optionally, the second interconnecting gate line includes a plurality of second sub-gate lines, with at least every two second fine gates correspondingly connected to one second sub-gate line, and each second sub-gate line at least partially passing through the substrate and connected to the second bus gate line.

[0012] Optionally, the substrate has at least one first through-hole, through which the first grid structure is connected to the first bus grid.

[0013] Optionally, the diameter of the first through hole ranges from 50 to 500 μm.

[0014] Optionally, the minimum distance from the center of the first through hole to the edge of the substrate is greater than or equal to 1.5 mm.

[0015] Optionally, the substrate has at least one second through-hole, through which the second grid structure passes and is connected to the second bus grid.

[0016] Optionally, the diameter of the second through hole ranges from 50 to 500 μm.

[0017] Optionally, the minimum distance from the center of the second through hole to the edge of the substrate is greater than or equal to 1.5 mm.

[0018] A battery assembly includes the aforementioned battery cells, wherein a plurality of the battery cells are partially overlapped in a first direction, wherein the first grid structure on the first surface of one of two adjacent battery cells and the second busbar grid on the second surface of the other are in conductive contact, and / or the second grid structure on the first surface of one of two adjacent battery cells and the first busbar grid on the second surface of the other are in conductive contact.

[0019] Optionally, a conductive material is provided in the overlapping area between the plurality of battery cells, the conductive material including conductive adhesive or conductive silver paste.

[0020] A photovoltaic system includes the aforementioned battery module. The technical effects of this application are the same as those of the aforementioned battery module, and will not be repeated here. Attached Figure Description

[0021] Figures 1 to 8 These are schematic diagrams of various embodiments of the back contact battery cells provided in this application;

[0022] Figures 9 to 10 These are schematic diagrams of various embodiments of the battery assembly provided in this application.

[0023] Explanation of reference numerals in the attached figures:

[0024] 100, Substrate; 101, First surface; 102, Second surface; 200, First gate structure; 201, First fine gate; 202, First interconnect gate line; 2021, First sub-gate line; 300, Second gate structure; 301, Second fine gate; 302, Second interconnect gate line; 3021, Second sub-gate line; 400, First bus gate line; 500, Second bus gate line; 600, First via; 700, Second via. Detailed Implementation

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] like Figures 1 to 8 As shown, a back-contact solar cell includes a substrate 100. The substrate 100 serves as the support and foundation of the solar cell, and possesses excellent semiconductor properties and mechanical stability. The material of the substrate 100 can be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material can be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing monocrystalline and amorphous states is called microcrystalline). For example, silicon can be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. Preferably, the substrate 100 is made of n-type monocrystalline silicon, which is free from photo-induced degradation.

[0032] The substrate 100 has a first surface 101 and a second surface 102 disposed opposite to each other. In one embodiment of this application, the substrate 100 has a front side facing the sun during normal operation and a back side opposite to the front side, the front side being the light-receiving surface; the back side is disposed on the other side of the substrate 100 opposite to the front side, that is, the aforementioned front side and back side are located on different sides of the substrate 100 and are opposite sides. In this embodiment, the first surface 101 is the backlighting surface and the second surface 102 is the light-receiving surface.

[0033] The first grid line structure 200 and the second grid line structure 300 are spaced apart on the first surface 101. Understandably, the grid line structures are used to collect photogenerated carriers generated inside the solar cell. Generally speaking, the first grid line structure 200 and the second grid line structure 300 are arranged spaced apart on the entire back surface of the solar cell, and the first grid line structure 200 and the second grid line structure 300 are respectively disposed in different doped regions of the solar cell. The polarities of the first grid line structure 200 and the second grid line structure 300 are opposite. For example, the first grid line structure 200 can be a positive grid line and the second grid line structure 300 can be a negative grid line, or the first grid line structure 200 can be a negative grid line and the second grid line structure 300 can be a positive grid line. This application does not limit this.

[0034] In some embodiments, the back-contact solar cell includes a first busbar 400 disposed on the second surface 102. The first busbar structure 200 at least partially passes through the substrate 100 and is connected to the first busbar 400. Based on this structure, the charge carriers collected by the first busbar structure 200 on the back of the solar cell can flow to the first busbar 400 on the front of the solar cell. In this way, a first busbar 400 electrically connected to the first busbar structure 200 on the back of the solar cell can be formed on the front of the solar cell, providing a structural basis for contact conductivity between the solar cells.

[0035] In some embodiments, the back-contact solar cell includes a second busbar 500 disposed on the second surface 102, with the second busbar structure 300 at least partially passing through the substrate 100 and connected to the second busbar 500. Based on the above structure, the charge carriers collected by the second busbar structure 300 on the back side of the solar cell can be channeled to the second busbar 500 on the front side of the solar cell. Thus, a second busbar 500 electrically connected to the second busbar structure 300 on the back side of the solar cell can be formed on the front side of the solar cell, providing a structural basis for contact conductivity between the solar cells.

[0036] In this application, through the above-described structural design, the grid structure of the first surface 101 is configured to partially pass through the substrate 100 and connect to the busbar grid of the second surface 102, thereby drawing the charge carriers on the back of the cell to the front of the cell. In this way, the grid structure of the first surface 101 of one of the two adjacent cells is directly connected to the busbar grid of the second surface 102 of the other cell to achieve interconnection between the adjacent cells. No solder strip is required, which shortens the movement distance of the charge carriers, saves the investment in string bonding equipment, simplifies the process production steps of the battery module, and the overlapping interconnection between adjacent cells eliminates the gap between the cells, further improving the power density of the module.

[0037] In some embodiments, the first grid structure 200 includes a plurality of first fine grids 201, which extend along a first direction and are spaced apart along a second direction. At least a portion of the first fine grids 201 pass through the substrate 100 and are connected to the first busbar 400. Preferably, each first fine grid 201 passes through the substrate 100 and is connected to the first busbar 400. In this way, each first fine grid 201 is independently connected to the first busbar 400, and each first fine grid 201 independently collects the charge carriers inside the solar cell. Each first fine grid 201 is independently connected to the first busbar structure, ensuring that the current collected by each first fine grid 201 can flow into the first busbar structure with the shortest path. This reduces the resistance loss of current in the fine grid network. Even if individual first fine grids 201 have problems during manufacturing or use (such as breakage), it will not affect the normal operation of other first fine grids 201, thus providing long-term reliability.

[0038] In some embodiments, the first grid structure 200 includes a plurality of first fine grids 201 and first interconnect grid lines 202 connected to the plurality of first fine grids 201. The first interconnect grid lines 202 at least partially pass through the substrate 100 and are connected to the first bus grid line 400. In this structural design, by setting the first interconnect grid lines 202 to interconnect the various first fine grids 201 on the back side of the solar cell, and then setting the first interconnect grid lines 202 to partially pass through the substrate 100 and connect to the first bus grid line 400, current can be transmitted to the front side of the solar cell. This can effectively reduce the number of openings in the substrate 100 and avoid structural damage caused by excessive openings in the substrate 100. Exemplarily, the first interconnect grid lines 202 can be a continuous linear structure.

[0039] In some embodiments, the first interconnect gate line 202 includes a plurality of first sub-gate lines 2021, with at least every two first fine gates 201 correspondingly connected to one first sub-gate line 2021. Each first sub-gate line 2021 at least partially passes through the substrate 100 and is connected to the first bus gate line 400. That is, the first interconnect gate line 202 can be a plurality of spaced first sub-gate lines 2021, with a portion of the first gate line and each first sub-gate line 2021 correspondingly connected to form various local interconnect structures. Each first sub-gate line 2021 is connected to the first bus gate line 400, which can improve the carrier collection efficiency on the one hand, and reduce the number of holes to be drilled in the substrate 100 on the other hand.

[0040] In some embodiments, the second grid structure 300 includes a plurality of second fine grids 301, which extend along a first direction and are spaced apart along a second direction. At least a portion of the second fine grids 301 pass through the substrate 100 and are connected to the second bus grid 500. Preferably, each second fine grid 301 passes through the substrate 100 and is connected to the second bus grid 500. In this way, each second fine grid 301 is independently connected to the second bus grid 500, and each second fine grid 301 independently collects the charge carriers inside the solar cell. Each second fine grid 301 is independently connected to the second bus structure, ensuring that the current collected by each second fine grid 301 can flow into the second bus structure with the shortest path. This reduces the resistance loss of current in the fine grid network. Even if individual second fine grids 301 have problems during manufacturing or use (such as breakage), it will not affect the normal operation of other second fine grids 301, thus providing long-term reliability.

[0041] The second grid structure 300 includes a plurality of second fine grids 301 and second interconnecting grid lines 302 connecting the plurality of second fine grids 301. The second interconnecting grid lines 302 at least partially pass through the substrate 100 and are connected to the second busbar 500. In this structural design, by setting the second interconnecting grid lines 302 to interconnect the various second fine grids 301 on the back side of the solar cell, and then setting the second interconnecting grid lines 302 to partially pass through the substrate 100 and connect to the second busbar 500, current can be transmitted to the front side of the solar cell. This can effectively reduce the number of openings in the substrate 100 and avoid structural damage caused by excessive openings in the substrate 100. For example, the second interconnecting grid lines 302 can be a continuous linear structure.

[0042] In some embodiments, the second interconnect gate line 302 includes a plurality of second sub-gate lines 3021, with at least every two second fine gates 301 correspondingly connected to one second sub-gate line 3021. Each second sub-gate line 3021 at least partially passes through the substrate 100 and is connected to the second bus gate line 500. That is, the second interconnect gate line 302 can be a plurality of spaced second sub-gate lines 3021, with a portion of the second gate line and each second sub-gate line 3021 correspondingly connected to form various local interconnect structures. Each second sub-gate line 3021 is connected to the second bus gate line 500, which can improve the carrier collection efficiency on the one hand, and reduce the number of holes to be drilled in the substrate 100 on the other hand.

[0043] The substrate 100 has at least one first through-hole 600, through which the first grid structure 200 passes and is connected to the first busbar 400. Exemplarily, one or more micron-sized first through-holes 600 can be precisely drilled on the substrate 100 using a laser to form conductive channels, allowing the first grid structure 200 on the back side of the solar cell to be directly connected to the first busbar 400 on the back side, forming a conductive contact structure on the front side of the solar cell.

[0044] Further, the pore size of the first through-hole ranges from 50 to 500 μm, preferably from 50 to 350 μm. Exemplarily, the pore size of the first through-hole can be 50 μm, 100 μm, 200 μm, 300 μm, 350 μm, 500 μm, etc., and this application does not impose any limitation thereon. By limiting the pore size of the first through-hole to the above range, it is possible to avoid damage to the substrate structure caused by an excessively large pore size, and also to avoid affecting the passage of slurry if the pore size is too small.

[0045] Furthermore, the minimum distance from the center of the first through hole to the edge of the substrate is greater than or equal to 1.5 mm. In other words, the distance between the center of the first through hole and the edge of the substrate closest to the first through hole is greater than or equal to 1.5 mm. This can avoid damage to the structure of the substrate edge caused by drilling and reduce the risk of microcracks in the substrate.

[0046] The substrate 100 has at least one second through-hole 700, through which the second grid structure 300 passes and is connected to the second busbar 500. Exemplarily, one or more micron-sized second through-holes 700 can be precisely drilled on the substrate 100 using a laser to form conductive channels, allowing the second grid structure 300 on the back side of the solar cell to be directly connected to the second busbar 500 on the back side, forming a conductive contact structure on the front side of the solar cell.

[0047] Further, the pore size of the second through hole ranges from 50 to 500 μm, preferably from 50 to 350 μm. Exemplarily, the pore size of the second through hole can be 50 μm, 100 μm, 200 μm, 300 μm, 350 μm, 500 μm, etc., and this application does not impose any limitation thereon. By limiting the pore size of the second through hole to the above range, it is possible to avoid damage to the substrate structure caused by an excessively large pore size, and also to avoid affecting the passage of slurry if the pore size of the second through hole is too small.

[0048] Furthermore, the minimum distance from the center of the second through hole to the edge of the substrate is greater than or equal to 1.5 mm. In other words, the distance between the center of the second through hole and the edge of the substrate closest to the second through hole is greater than or equal to 1.5 mm. This can avoid damage to the structure of the substrate edge caused by drilling and reduce the risk of microcracks in the substrate.

[0049] like Figures 9 to 10 As shown, a battery module includes the aforementioned battery cells, with multiple battery cells partially overlapping in a first direction. Specifically, the first grid structure 200 of the first surface 101 of one adjacent battery cell and the second busbar 500 of the second surface 102 of the other battery cell are in conductive contact, and / or, the second grid structure of the first surface 101 of one adjacent battery cell and the first busbar 400 of the second surface 102 of the other battery cell are in conductive contact. In this battery module, through the above structural design, adjacent battery cells can be directly interconnected by the direct overlap of the busbar of one cell with the opposite grid structure of the other, eliminating the need for solder strips. Charge carriers are directly connected through the busbars and grid structures to form cross-cell transmission, shortening the lateral current flow distance. Furthermore, the solder strip-free structure eliminates the need for string bonding equipment, simplifying the battery module manufacturing process. The overlapping interconnection of the grid structures and busbars of adjacent battery cells eliminates the gap between cells, further increasing the module's power density. Furthermore, conductive material, including conductive adhesive, conductive silver paste, or solder paste, is provided in the overlapping areas between multiple solar cells. This conductive material enhances both the connection strength between the solar cells and the current transmission efficiency between them.

[0050] In some embodiments, 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.

[0051] 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.

[0052] 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 back contact battery cell, characterized in that, The device includes a substrate having a first surface and a second surface disposed opposite to each other, a first grid line structure and a second grid line structure spaced apart on the first surface; a first bus grid line disposed on the second surface, the first grid line structure passing through the substrate and connected to the first bus grid line; and / or a second bus grid line disposed on the second surface, the second grid line structure passing through the substrate and connected to the second bus grid line.

2. The back contact battery cell as described in claim 1, characterized in that, The first grid structure includes a plurality of first fine grids, which extend along the first direction and are spaced apart along the second direction. At least a portion of the first fine grids pass through the substrate and are connected to the first bus grid.

3. The back contact battery cell as described in claim 1, characterized in that, The first gate structure includes a plurality of first fine gates and a first interconnect gate line connected to the plurality of first fine gates, wherein the first interconnect gate line at least partially passes through the substrate and is connected to the first bus gate line.

4. The back contact battery cell as described in claim 3, characterized in that, The first interconnecting gate line includes a plurality of first sub-gate lines, with at least every two first fine gates correspondingly connected to one first sub-gate line, and each first sub-gate line at least partially passing through the substrate and connected to the first bus gate line.

5. The back contact battery cell as described in claim 1, characterized in that, The second grid structure includes a plurality of second fine grids, which extend along the first direction and are spaced apart along the second direction. At least a portion of the second fine grids pass through the substrate and are connected to the second bus grid.

6. The back contact battery cell as described in claim 1, characterized in that, The second gate structure includes a plurality of second fine gates and a second interconnect gate line connected to the plurality of second fine gates, wherein the second interconnect gate line at least partially passes through the substrate and is connected to the second bus gate line.

7. The back contact battery cell as described in claim 6, characterized in that, The second interconnecting gate line includes a plurality of second sub-gate lines, with at least every two second fine gates correspondingly connected to one second sub-gate line, and each second sub-gate line at least partially passing through the substrate and connected to the second bus gate line.

8. The back contact battery cell as described in claim 1, characterized in that, The substrate has at least one first through hole, and the first grid structure passes through the first through hole and is connected to the first bus grid.

9. The back contact battery cell as described in claim 8, characterized in that, The diameter of the first through hole ranges from 50 to 500 μm.

10. The back contact battery cell as described in claim 8, characterized in that, The minimum distance from the center of the first through hole to the edge of the substrate is greater than or equal to 1.5 mm.

11. The back contact battery cell as described in claim 1, characterized in that, The substrate has at least one second through hole, and the second grid structure passes through the second through hole and is connected to the second bus grid.

12. The back contact battery cell as described in claim 11, characterized in that, The diameter of the second through hole ranges from 50 to 500 μm.

13. The back contact battery cell as described in claim 11, characterized in that, The minimum distance from the center of the second through hole to the edge of the substrate is greater than or equal to 1.5 mm.

14. A battery assembly, characterized in that, The battery cell includes any one of claims 1-13, wherein a plurality of the battery cells are partially overlapped in the first direction, wherein the first grid structure on the first surface of one of two adjacent battery cells and the second bus grid on the second surface of the other are in conductive contact, and / or the second grid structure on the first surface of one of two adjacent battery cells and the first bus grid on the second surface of the other are in conductive contact.

15. The battery assembly as claimed in claim 14, characterized in that, A conductive material is disposed in the overlapping area between the multiple battery cells, the conductive material including conductive adhesive or conductive silver paste.

16. A photovoltaic system, characterized in that, Includes the battery assembly as described in any one of claims 14-15.

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