Battery string and photovoltaic module

Abstract

The battery string of the present application comprises: a series unit; each series unit comprises an electric connecting wire, a first battery piece, a second battery piece and a plurality of bonding parts; each of the first cell and the second cell comprises a cell edge, a front surface and a back surface; the electric connecting wire is electrically connected with the front surface of the first battery piece and the back surface of the second battery piece; the plurality of bonding parts comprise front bonding parts and back bonding parts; the battery edge comprises a chamfered edge and a cut edge, and the chamfered edge of the first battery piece is adjacent to the cut edge of the second battery piece; the distance between a first front edge bonding part, farthest from the second battery piece, in the first battery piece and an adjacent cutting edge is S1, and the distance between a second front edge bonding part adjacent to the second battery piece and an adjacent chamfering edge is S3; the distance between a first back edge bonding part, farthest from the first battery piece, in the second battery piece and an adjacent chamfer edge is S2, and the distance between a second back edge bonding part adjacent to the first battery piece and an adjacent cutting edge is S4; s1 is greater than S3, and / or S4 is greater than S2.

Description

Technical Field

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

[0002] With the development and widespread application of solar cell technology, photovoltaic power generation has become one of the most competitive energy forms in the future. Solar cells can convert solar energy into electrical energy and have a wide range of applications.

[0003] Because a single solar cell outputs a relatively low voltage, multiple cells are connected in series to form a battery string, thus expanding its application scenarios. However, existing battery strings suffer from limited bonding between the electrical connections and the cells, resulting in poor connection strength and affecting the long-term reliability of the battery string. Summary of the Invention

[0004] In view of this, in order to at least partially solve the aforementioned technical problems, this application provides a battery string and a photovoltaic module.

[0005] According to one embodiment of this application, a battery string is provided, comprising: at least one series unit; the series unit includes: an electrical connection wire, a first battery cell and a second battery cell adjacent to each other in the extending direction of the electrical connection wire, and a plurality of adhesive portions disposed on the electrical connection wire; both the first battery cell and the second battery cell include a battery body, the battery body including: a battery edge and opposing front and back sides; the electrical connection wire is electrically connected to the front side of the first battery cell and the back side of the second battery cell; the plurality of adhesive portions include a plurality of front adhesive portions located on the front side and a plurality of back adhesive portions located on the back side; the battery edge includes: a chamfered edge with a chamfer and a cut edge without a chamfer formed by cutting, the chamfered edge and the cut edge on the battery body being opposite to each other;

[0006] In the series unit, the chamfered edge of the first battery cell and the cut edge of the second battery cell are adjacent; along the extension direction of the electrical connection line, in the first battery cell: the distance between the first front edge bonding portion J1, which is furthest from the second battery cell, and its adjacent cut edge is S1, and the distance between the second front edge bonding portion J3, which is adjacent to the second battery cell, and its adjacent chamfered edge is S3; in the second battery cell: the distance between the first back edge bonding portion J2, which is furthest from the first battery cell, and its adjacent chamfered edge is S2, and the distance between the second back edge bonding portion J4, which is adjacent to the first battery cell, and its adjacent cut edge is S4; wherein, S1 > S3, and / or, S4 > S2.

[0007] According to another embodiment of this application, a photovoltaic cell is provided, comprising a plurality of the aforementioned cell strings.

[0008] According to the photovoltaic module provided in the above embodiments of this application, by differentially setting the distance between the bonding portion and the edge of the adjacent cell near the chamfered edge and near the cut edge in adjacent first and second cells, it helps to balance the mechanical stress at different edges of the cells. For example, the cut edge is more likely to form a stress concentration point. By differentially setting the distance between the end bonding portion and the edge of the adjacent cell in the extension direction of the electrical connection line, while maintaining good bonding strength between the electrical connection line and the cell, the risk of microcracks or breakage during the manufacturing, handling, or use of the module is reduced, thereby improving the long-term reliability of the module. Attached Figure Description

[0009] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments of this application with reference to the accompanying drawings.

[0010] Figure 1 A schematic diagram of the structure of a series unit in an embodiment of this application is shown;

[0011] Figure 2 A partial structural schematic diagram of a series unit in an embodiment of this application is shown;

[0012] Figure 3 This paper shows another partial structural schematic diagram of a series unit in an embodiment of the present application;

[0013] Figure 4 A cross-sectional view of the adhesive portion in an embodiment of this application is shown.

[0014] The meanings of the reference numerals in the above figures are as follows:

[0015] 1. Series unit;

[0016] 11. Electrical connection wires;

[0017] 12. First solar cell;

[0018] 13. Second solar cell;

[0019] 14. Adhesive section;

[0020] J1, First front edge adhesive portion; J3, Second front edge adhesive portion; J2, First back edge adhesive portion; J4, Second back edge adhesive portion;

[0021] 15. Battery body;

[0022] 151. Battery edge;

[0023] 1511. Chamfered edge; 1512. Cut edge;

[0024] 16. Collector electrode;

[0025] 17. Solder pads;

[0026] 171. First front edge pad; 172. Second front edge pad; 173. First back edge pad; 174. Second back edge pad. Detailed Implementation

[0027] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0029] When using expressions such as "at least one of A, B or C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B or C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B, and C, etc.).

[0030] In this application, the relative position between two components (e.g., a membrane or region), as referred to by terms such as "above," "on," or "above," can mean that the two components are in direct contact or that they are not in direct contact. Similarly, the relative position between two components, as referred to by terms such as "below," "under," or "below," can mean that the two components are in direct contact or that they are not in direct contact. For example, when one component (e.g., a membrane or region) is referred to as "on another component," it can be directly on the other component, or there may be other components between them. On the other hand, when a component is referred to as "directly on another component," there are no components between them. Furthermore, when one component is referred to as "on another component," the two components have a vertical relationship in the planar view, and this component can be above or below the other component, thus this vertical relationship depends on the orientation of the device.

[0031] In related technologies, for solar cells, such as bifacial cells, when the surface of the cell does not have a main grid (OBB technology), the grid is directly connected to the solder ribbon. To improve the adhesion between the solder ribbon and the cell, adhesive dots are usually printed above or below the solder ribbon to ensure the reliability of the connection between the solder ribbon and the cell. However, arbitrarily setting the position of the adhesive dots not only increases the cost of adhesive consumption but also makes it difficult to guarantee the reliability of the connection between the solder ribbon and the cell.

[0032] In realizing the concept of this application, it was discovered that, based on the different stresses at different locations on the substrate edge, the position of the end bonding portion adjacent to the edge of the cell is set differently, which can reduce the risk of cell cracking or microcracks that may easily occur during transportation, lamination or long-term outdoor operation.

[0033] Figure 1 A schematic diagram of the structure of a series unit in an embodiment of this application is shown; Figure 2 A partial structural schematic diagram of a series unit in an embodiment of this application is shown. Figure 3 A partial structural schematic diagram of a series unit according to an embodiment of this application is shown. For ease of understanding this application, Figure 2 In the image, the left side shows the front of the first solar cell, and the right side shows the back of the second solar cell (the edges, electrical connections, and bonding areas on the back of the cells are indicated by dashed lines). It should be noted that... Figures 1-2 All dimensions are for illustrative purposes only and do not represent the relative sizes. The relationships between relative sizes are subject to the textual description. The dimensions of the adhesive dots (adhesive part 14) in the above figures are for illustrative purposes only and do not represent the actual dimensions.

[0034] This implementation method uses a TOPCon battery string as an example for illustration. Figures 1-3 As shown, the battery string includes at least one series-connected unit 1. This application does not specifically limit the number of series-connected units 1; there can be one or more. In the battery string, adjacent series-connected units 1 are electrically connected; this electrical connection can be in series or in parallel, and this application does not impose any particular limitation on this.

[0035] The series unit 1 includes: an electrical connection wire 11, a first battery cell 12, a second battery cell 13, and multiple adhesive portions 14.

[0036] Electrical connection wire 11 (also called solder strip or conductive interconnect strip) is used to electrically connect two adjacent battery cells, and can be as follows: Figure 1 The first battery cell 12 and the second battery cell 13 shown are adjacent to each other in the extension direction of the electrical connection line 11. The extension direction of the electrical connection line 11 can be the direction in which the length of the electrical connection line 11 is (e.g., Figure 1 (The first direction shown).

[0037] Multiple adhesive portions 14 are disposed on the electrical connection wire 11 to bond and fix the electrical connection wire 11 to the surfaces of the first battery cell 12 and the second battery cell 13. The multiple adhesive portions 14 may at least partially cover the electrical connection wire 11.

[0038] It is understood that the aforementioned "multiple adhesive portions 14" can refer to some or all of the adhesive portions 14. Unless otherwise specified, the "multiple adhesive portions 14" mentioned below refers to the foregoing meaning. The aforementioned "at least partially covering" can be understood as the adhesive portions 14 completely covering the electrical connection wire 11, or the adhesive portions 14 partially covering the electrical connection wire 11, so that the electrical connection wire 11 can be partially exposed, thereby improving light utilization.

[0039] Both the first solar cell 12 and the second solar cell 13 include a solar cell body. The material of the solar cell body can be an n-type, p-type, or intrinsic crystalline silicon substrate, such as a semiconductor material selected from monocrystalline silicon, polycrystalline silicon, and microcrystalline silicon. It can also be an n-type or p-type monocrystalline silicon substrate. Solar cells based on monocrystalline silicon substrates have higher conversion efficiency compared to other types, such as polycrystalline silicon solar cells. By introducing donor impurities such as group VA elements such as phosphorus (P), arsenic (As), or antimony (Sb) into these semiconductor materials, an n-type crystalline silicon substrate can be obtained. Alternatively, by introducing acceptor impurities such as group IIIA elements such as boron (B), aluminum (Al), or gallium (Ga) into these semiconductor materials, a p-type crystalline silicon substrate can be obtained.

[0040] The battery body can be understood as generating and separating charge carriers during normal operation. Charge carriers can be holes or electrons. The battery body includes a battery edge 151 and opposing front and back sides. The battery edge 151 refers to the edge of the battery body, which can be a cut edge without chamfers or a chamfered edge, etc. Electrical connection wires 11 are electrically connected to the front side of the first battery cell 12 and the back side of the second battery cell 13. It should be noted that the battery cell has a sheet-like structure. The side that absorbs light energy and converts it into electrical energy is called the light-absorbing surface or front side, and the other side is called the back side or back side. In this embodiment, when the photovoltaic module is normally installed and used, the side of the battery cell facing the sun is called the front side, and the side opposite the front side is called the back side. As mentioned above, the front side of the first battery cell 12 can be located on... Figure 2 The left-hand side of the surface facing the viewpoint, the back of the second battery cell 13 can be located on... Figure 2 The surface facing the viewpoint on the right side of the image. Multiple adhesive portions 14 may include several front adhesive portions located on the front side (e.g., ... Figure 2 The adhesive portion on the left side of the battery cell (as shown) and several back adhesive portions on the back side (such as...) Figure 2 (The adhesive portion on the right-hand battery cell is shown).

[0041] The battery edge 151 includes a chamfered edge 1511 and a cut edge 1512 formed by cutting without chamfering. The cut edge 1512 can be understood as being formed by cutting the entire battery cell, for example, by laser cutting. It is understood that during the cutting process, certain structural defects may be caused, making the cut edge 1512 without chamfering more prone to stress concentration points. The chamfered edge 1511 and the cut edge 1512 on the battery body are opposite each other. It is understood that the chamfered edge 1511 and the cut edge 1512 are located at both ends of the first battery cell 12 and / or the second battery cell 13 along the first direction. In the series unit 1, the chamfered edge 1511 of the first battery cell 12 and the cut edge 1512 of the second battery cell 13 are adjacent.

[0042] Chamfered edge 1511 can include, for example Figure 2 The curved chamfers at the right ends of the two battery cells shown can also include chamfers formed by inclined straight lines, and the cut edge 1512 can include, for example... Figure 2 The right angle at the left end of the two battery cells shown. Figure 2 This is shown as an example only and does not imply any particular limitation on the shape of the chamfered edge 1511 and the cut edge 1512.

[0043] The series unit 1 also includes: multiple current collector electrodes 16 (also called fine grids, current collector grid lines, sub-grids, etc.), located on the surface of the battery body, the multiple current collector electrodes 16 in a first direction (e.g. Figures 2-3 As shown in the left and right directions, they are spaced apart and along the second direction (such as...) intersecting the first direction. Figures 2-3 Extending in the vertical direction (as shown), it collects the current generated in the battery body. Multiple electrical connection lines 11 are suitable for collecting and transmitting the current collected from the current collector 16. The number of current collectors 16 in the series unit 1 is not specifically limited.

[0044] It should be noted that the adhesive portion 14 can be disposed between adjacent current collector electrodes 16, which helps to strengthen the connection strength between the electrical connection line 11 and the battery body, and prevents the adhesive portion 14 from spreading between the current collector electrode 16 and the electrical connection line 11, thus affecting the current transmission between the electrical connection line 11 and the current collector electrode 16 and resulting in a lower yield of the photovoltaic module. The adhesive portion 14 can also cover at least one current collector electrode 16, for example, it can cover two current collector electrodes 16. This arrangement helps to provide an effective bonding and fixing effect through the adhesive portion 14.

[0045] like Figure 2As shown, along the extension direction (first direction) of the electrical connection line 11, in the first battery cell 12, the distance between the first front edge bonding portion J1, which is furthest from the second battery cell 13, and its adjacent cut edge 1512 is S1; the distance between the second front edge bonding portion J3, which is adjacent to the second battery cell 13, and its adjacent chamfer edge 1511 is S3. In the second battery cell 13: the distance between the first back edge bonding portion J2, which is furthest from the first battery cell 12, and its adjacent chamfer edge 1511 is S2; the distance between the second back edge bonding portion J4, which is adjacent to the first battery cell 12, and its adjacent cut edge 1512 is S4. Wherein, S1 > S3, and / or, S4 > S2.

[0046] According to embodiments of this application, in the same solar cell, the cutting process based on the cut edge 1512 is prone to structural defects, making the cut edge 1512 more likely to form stress concentration points than the chamfered edge 1511. By setting S1 to be larger than S3, and / or setting S4 to be larger than S2, the stress concentration points formed during the curing and shrinkage of the adhesive portion 14 during the process of fixing the electrical connection wire 11 through the adhesive portion 14 are kept as far away from the cut edge 1512 as possible. This results in a larger deformation buffer zone near the cut edge 1512 in the solar cell, thereby reducing the occurrence of microcracks or fragments during solar cell transportation, lamination, or use, while also ensuring a good fixing effect on the electrical connection wire 11, improving the yield and reliability of the module.

[0047] It is understood that this application does not require S1 > S3 and S4 > S2 to be true simultaneously. In some embodiments, S1 > S3, and the relationship between S4 and S2 is not fixed and can be adjusted based on actual needs. In other embodiments, S4 > S2, and the relationship between S1 and S3 is not fixed and can be adjusted based on actual needs. In still other embodiments, S1 > S3, and S4 > S2.

[0048] It should be noted that the adhesive portion 14 has two ends along the first direction. S1 can be understood as the end of the first front edge adhesive portion J1 closest to its adjacent cut edge 1512, and the distance between it and the cut edge 1512 along the first direction. S4 can be understood as the end of the second back edge adhesive portion J4 closest to its adjacent cut edge 1512, and the distance between it and the cut edge 1512 along the first direction. S3 can be understood as the end of the second front edge adhesive portion J3 closest to its adjacent chamfered edge 1511, and the distance between it and the chamfered edge 1511 along the first direction. S2 can be understood as the end of the first back edge adhesive portion J2 closest to its adjacent chamfered edge 1511, and the distance between it and the chamfered edge 1511 along the first direction.

[0049] In some embodiments, the first battery cell 12 and the second battery cell 13 may include cut battery cells.

[0050] Cutting a solar cell refers to the process of cutting a single solar cell into M individual cells, where 2 ≤ M ≤ 8. It can be understood that this application involves cutting a large silicon wafer solar cell (e.g., (120mm~300mm) × (156mm~300mm), where the entire cell can be a square or rectangular wafer with chamfered corners) into 2~8 individual cells.

[0051] Optionally, M can be, for example, 2, 3, 4, 5, 6, 7 or 8, and this application does not impose any particular limitation on it.

[0052] Preferably, M is, for example, 2. The length of the solar cell along the second direction is 180~220mm, and the width along the first direction is 90~110mm. This length and width setting achieves a balance between module power, output current, and overall performance, resulting in better performance. When M=2, each solar cell has two opposite cut edges 1512 and two chamfered edges 1511 along the first direction.

[0053] In some embodiments, an auxiliary soldering layer may be provided between the electrical connection line 11 and the current collector 16. This layer may be solder, solder paste, or solder, for soldering the current collector 16 to the electrical connection line 11. Alternatively, it may be a conductive bonding layer, such as conductive silver paste or conductive adhesive, for conductive bonding between the current collector 16 and the electrical connection line 11.

[0054] Optionally, the electrical connection wire 11 can be made of materials such as copper, silver, silver-clad copper, copper-aluminum alloy, or copper-clad aluminum.

[0055] Optionally, the electrical connection line 11 and the current collector 16 may be metal strips with various cross-sectional shapes, such as circular, triangular, rectangular, flat, elliptical or chamfered rectangles, etc., which are not particularly limited in this application.

[0056] In some implementations, S1 > S2. Similar to the above, in adjacent solar cells, based on the tendency for stress concentration points to form during the cutting process, by setting S1 larger than S2, the stress concentration points formed during the curing and shrinkage of the adhesive portion 14 during the fixing of the electrical connection wire 11 are kept as far away as possible from the cutting edge 1512. This results in a larger deformation buffer zone near the cutting edge 1512, thereby reducing the occurrence of microcracks or fragments during solar cell transport, lamination, or use, while also ensuring good fixing of the electrical connection wire 11, improving the yield and reliability of the module.

[0057] In some implementations, S3 < S4. In adjacent cells, similarly to the above, based on the tendency to form stress concentration points during the cutting process, S4 is set to be larger than S3, so that the cell has a larger deformation buffer zone near the cut edge 1512, thereby reducing the occurrence of microcracks or fragments during cell transportation, lamination or use.

[0058] It is understood that this application does not require S1 > S2 and S3 < S4 to be true simultaneously. In some embodiments, S1 > S2, and the relationship between S3 and S4 is not fixed and can be adjusted based on actual needs. In other embodiments, S4 > S3, and the relationship between S1 and S2 is not fixed and can be adjusted based on actual needs. In still other embodiments, S1 > S3, and S4 > S3.

[0059] In some embodiments, on adjacent first and second battery cells 12 and 13, along the first direction, S1-S2 ≤ 5mm. This arrangement allows multiple adhesive portions 14 to be evenly distributed on the first and second battery cells 12 and 13, resulting in more uniform stress distribution on the first and second battery cells 12 and 13 during lamination, especially at the edges of the first and second battery cells 12 and 13 near the start and end points of the electrical connection lines. This avoids the risk of battery cell fragmentation or microcracks caused by localized stress concentration.

[0060] Optionally, the difference between S1 and S2 can be, for example, 1 mm, 2 mm, 3 mm, 4 mm or 5 mm, or a range consisting of any two of the above values.

[0061] Alternatively, the difference between S1 and S2 can be less than 3 mm. This setting further avoids stress concentration.

[0062] In some implementations, S1-S3 ≤ 5mm. This setting ensures that the stress near the two opposite edges of the solar cell is more uniform during lamination, avoiding the risk of solar cell fragmentation or microcracks caused by localized stress concentration.

[0063] Optionally, the difference between S1 and S3 can be, for example, 1 mm, 2 mm, 3 mm, 4 mm or 5 mm, or a range consisting of any two of the above values.

[0064] Alternatively, the difference between S1 and S3 can be less than 3 mm. This setting further avoids stress concentration.

[0065] In some implementations, S4-S2 ≤ 5mm. This setting ensures that the stress near the two opposite edges of the solar cell is more uniform during lamination, avoiding the risk of solar cell fragmentation or microcracks caused by localized stress concentration.

[0066] Optionally, the difference between S4 and S2 can be, for example, 1 mm, 2 mm, 3 mm, 4 mm or 5 mm, or a range consisting of any two of the above values.

[0067] Alternatively, the difference between S4 and S2 can be less than 3 mm. This setting further avoids stress concentration.

[0068] In some embodiments, an electrical connection 11 can connect adjacent first battery cell 12 and second battery cell 13. In the first battery cell 12, the battery edge 151 furthest from the second battery cell 13 (e.g., ...) Figure 2 The cut edge 1512 shown), and, in the second cell 13, the cell edge 151 furthest from the first cell 12 (as shown) Figure 2 Of the two chamfered edges 1511 shown, one is approximately the starting end of the electrical connection line 11, and the other is approximately the ending end of the electrical connection line 11. Since the electrical connection line 11 is heated at different locations and then connected to the battery cell (e.g., welded), and fixed after cooling, it is understood that compared to the middle position of the electrical connection line 11, the pull-out force at the connection points between the electrical connection line 11 and the battery cell near the starting and ending ends is relatively large, thus posing a higher risk of microcracks and breakage of the battery cell. In this embodiment, S1 > S4, and / or S3 < S2. For the starting and ending ends of the battery cell where the stress is relatively high, S1 and / or S2 are set to a larger buffer distance, so that the battery cell has a larger deformation buffer zone near the starting or ending end of the electrical connection line 11, avoiding high stress concentration and reducing the risk of cracking and microcracks at the battery edge 151 near the starting or ending end.

[0069] It is understood that this application does not require S1 > S4 and S2 > S3 to be true simultaneously. In some embodiments, S1 > S4, and the relationship between S2 and S3 is not fixed and can be adjusted based on actual needs. In other embodiments, S2 > S3, and the relationship between S1 and S4 is not fixed and can be adjusted based on actual needs. In still other embodiments, S1 > S4, and S2 > S3.

[0070] In some embodiments, the cells in the battery string can be gridless (OBB) cells; in other embodiments, the cells in the battery string can be grid-connected cells. Electrical connection line 11 is connected to the grid, and the grid is connected to the current collector 16.

[0071] In some embodiments, the first polarity current collector electrode is located on the front side of the first battery cell 12, and the second polarity current collector electrode is located on the back side of the second battery cell 13. Current output is achieved through the electrical connection of the electrical connection line 11. A solder pad 17 is provided between the electrical connection line 11 and the battery body. The solder pad can be understood as a thickened section on the electrical connection line 11 or a welding structure between the electrical connection line 11 and the battery body. Of course, an auxiliary welding layer can be provided between the solder pad 17 and the battery body as needed. The auxiliary welding layer can be, for example, solder, solder paste, or solder, for welding the battery body to the electrical connection line 11. The first front edge solder pad 171 is located between the first front edge bonding portion J1 and its adjacent cut edge 1512, and the second front edge solder pad 172 is located between the second front edge bonding portion J3 and its adjacent chamfered edge 1511. The first back edge pad 173 is located between the first back edge bonding portion J2 and its adjacent chamfered edge 1511, and the second back edge pad 174 is located between the second back edge bonding portion J4 and its adjacent cut edge 1512. This arrangement helps to strengthen the connection between the electrical connection wire 11 and the battery body, especially near the start and end ends, avoiding poor contact between the electrical connection wire 11 and the battery body that may occur during use or transportation, thereby improving the yield of the component.

[0072] In some embodiments, the front bonding portions on the first solar cell 12 and the second solar cell 13 are identical, as are the back bonding portions. That is, the front bonding portions on the first solar cell 12 and the second solar cell 13 can be obtained using the same screen printing / steel plate printing method, and similarly, the back bonding portions on the first solar cell 12 and the second solar cell 13 can also be obtained using the same screen printing / steel plate printing method. Within the allowable error range, the arrangement, position, and distance between the edge adhesive dots and the edge of the solar cell 12 and the second solar cell 13 of the front or back bonding portions are all the same. This ensures that different solar cells have approximately the same electrical connection wire fixing strength on the same side, reducing the risk of microcracks, cell breakage, and electrical connection wire detachment during lamination and transportation. It also simplifies the printing process and equipment for the bonding portions, improving production efficiency.

[0073] In some embodiments, the series unit 1 includes a plurality of electrical connection lines 11, as shown in the figure. Figure 2-3The first front edge adhesive portion J1, the second front edge adhesive portion J3, the first back edge adhesive portion J2, or the second back edge adhesive portion J4 on the multiple electrical connection lines 11 are arranged in a straight line in the second direction. That is, the first front edge adhesive portion J1, the second front edge adhesive portion J3, the first back edge adhesive portion J2, and the second back edge adhesive portion J4 on the multiple electrical connection lines 11 are arranged in a straight line in the second direction. This ensures that the stress near the multiple adhesive portions at the edge of the battery cell is uniform, reducing the risk of cracking and microcracks at the edge of the battery cell 151.

[0074] The distance between the second front edge bonding portion J3 and the second back edge bonding portion J4 is L2, and the distance between the second front edge pad 173 and the second back edge pad 174 is L3. L3 ≤ L2 ≤ 5 * L3. This configuration strengthens the fixing strength of the electrical connection wire 11 on the battery cell while allowing sufficient bending freedom for the electrical connection wire 11 near the distance between the first and second battery cells. It can be understood that in TOPcon batteries, such as... Figure 1 As shown, the front side of the first solar cell 12 needs to be connected to the back side of the second solar cell 13, requiring sufficient bending of the electrical connection wire 11. Adjusting L2 and L3 within the aforementioned range can reduce the risk of cell fragmentation and microcracks at the edges of the cell string gaps during module transport, lamination, or use. If L2 < L3, the electrical connection wire 11 is fixed too rigidly, making it difficult to form a certain degree of bending between the cell gaps, which greatly restricts the position between the interconnected cells, making stress concentration more likely at the cell edges, resulting in fragmentation and microcracks. If L2 > L3, it affects the bonding strength between the electrical connection wire 11 and the cell body, increasing the risk of the electrical connection wire 11 detaching due to mechanical impact or thermal expansion and contraction.

[0075] Optionally, the ratio between L2 and L3 can be, for example, 1, 2, 3, 4 or 5, or a range consisting of any two of the above values.

[0076] It should be noted that L3 can be understood as the distance along the first direction between the end of the second front edge pad 172 closest to its adjacent chamfer edge 1511 and the end of the second back edge pad 174 closest to its adjacent cut edge 1512; L2 can be understood as the distance along the first direction between the end of the second front edge bonding portion J3 closest to its adjacent chamfer edge 1511 and the end of the second back edge bonding portion J4 closest to its adjacent cut edge 1512.

[0077] In some implementations, the spacing between adjacent solar cells is -2 to 2 mm, which can be along a first direction and / or a second direction. This arrangement helps to increase the effective light-receiving area of ​​the module and improve its output power.

[0078] Specifically, in some embodiments, the spacing between adjacent solar cells along the first direction is less than 0 mm, and the adjacent solar cells partially overlap in the first direction; in other embodiments, the spacing between adjacent solar cells along the first direction is greater than 0 mm, and there is a gap between adjacent solar cells in the first direction.

[0079] Specifically, in some embodiments, the spacing between adjacent solar cells along the second direction is less than 0 mm, and the adjacent solar cells partially overlap in the second direction; in other embodiments, the spacing between adjacent solar cells along the second direction is greater than 0 mm, and there is a gap between adjacent solar cells in the second direction.

[0080] In some other embodiments, the spacing between adjacent solar cells along both the first and second directions is less than 0, and the adjacent solar cells along the first direction partially overlap and the adjacent solar cells along the second direction partially overlap.

[0081] For example, the spacing between adjacent solar cells along the first direction and / or the second direction can be, for example, -2 mm, -1.5 mm, 0 mm, 0.8 mm, 1 mm, 1.5 mm, or 2 mm, or a range consisting of any two of the above values. Preferably, it is -1 to 0 mm.

[0082] It is understood that when adjacent solar cells are partially stacked along the first direction, the second solar cell 13 can be disposed on the first solar cell 12 at the stacking location, thereby reducing the bending of the electrical connection line 11 at the solar cell stacking location and reducing the risk of microcracks and fragmentation.

[0083] It should be noted that an electrical connection line 11 is not limited to having only the first front edge pad 171, the second front edge pad 172, the first back edge pad 173, and the second back edge pad 174. In order to strengthen the bonding strength between the electrical connection line 11 and the battery body, multiple other pads can be distributed on the electrical connection line 11 as needed. This application mainly discusses the positional relationship between the end pads and the bonding portion 14, and the positions of other pads will not be described in detail.

[0084] Hereinafter, "pad 17" refers to "first front edge pad 171, second front edge pad 172, first back edge pad 173 or second back edge pad 174", which will not be elaborated further.

[0085] In some embodiments, the distance between the pad 17 and its adjacent battery edge 151 along the first direction is ≥4mm and ≤8mm. This configuration strengthens the bond between the electrical connection line 11 and the battery body, avoids the risk of the electrical connection line 11 desoldering or poor soldering, and improves the module yield.

[0086] Optionally, the distance between the pad 17 and its adjacent battery edge 151 along the first direction can be, for example, 4mm, 5mm, 6mm, 7mm or 8mm, or a range consisting of any two of the above values.

[0087] Preferably, the distance between the solder pad 17 and its adjacent battery edge 151 along the first direction is 6 mm. This arrangement ensures a good connection between the electrical connection line 11 and the battery body.

[0088] Furthermore, by differentiating the distances S1 and S4, and S3 and S2 between the front and back sides of the solar cell, it is helpful to stagger the bonding portions 14 on the front and back sides of the bifacial cells, avoiding stress concentration during lamination, further reducing the risk of microcracks or cell cracks, and improving the yield and reliability of the module.

[0089] In some embodiments, the total length Q (not shown in the figure) of the adhesive portion 14 on an electrical connection line 11 along the first direction on adjacent first and second battery cells 12 and 13 can be understood as the sum of the lengths of all adhesive portions 14 on an electrical connection line 11 along the first direction. An adhesive portion 14 has a contact area with the battery body. The length of the adhesive portion 14 along the first direction can be measured using an optical microscope or a scanning electron microscope (SEM). For example, a top-view SEM image of the adhesive portion 14 can be obtained first. Based on the height difference between the area with the adhesive portion 14 and other areas of the electrical connection line 11, and the obvious brightness difference in the SEM image, the length value at the corresponding position can be directly measured and calculated on the SEM image. The projected length W (not shown in the figure) of the electrical connection line 11 on the first and second battery cells 12 can be obtained by image capture, for example, by obtaining a top-view SEM image of the electrical connection line 11, and then measuring and calculating the length value at the corresponding position. The percentage of Q to W mentioned above is 2.5% to 48.5%. This configuration provides sufficient fixation for the electrical connection wire 11. If the ratio of the two is too low, it will affect the bonding strength between the electrical connection wire 11 and the battery body, increasing the risk of poor soldering or detachment of the electrical connection wire 11 due to thermal expansion and contraction or mechanical impact, thus affecting the effectiveness of the battery string. If the ratio of the two is too high, it will increase the cost of the adhesive part 14 material, and the increased obstruction of the battery body by the adhesive part 14 will affect the photoelectric conversion efficiency of the battery string.

[0090] Optionally, the percentage of Q to W can be, for example, 2.5%, 4.5%, 5%, 10%, 15%, 20%, 25%, 30%, 32.5%, 35%, 40%, 45%, or 48.5%, or a range consisting of any two of the above values.

[0091] In some embodiments, the projections of adjacent solar cells (e.g., first solar cell 12 and second solar cell 13) in the first direction overlap, and Q accounts for 2.5% to 32.5% of W. In other embodiments, the projections of adjacent solar cells (e.g., first solar cell 12 and second solar cell 13) in the first direction do not overlap, and Q accounts for 4.5% to 48.5% of W. In the case of overlapping projections, the percentage of Q can be appropriately reduced because the electrical connection wires 11 can be partially pressed down at the location of the partial stacking, providing a certain degree of fixing assistance, thereby relatively reducing the total length Q of the adhesive portion 14 along the first direction in the partial stacking configuration.

[0092] In some embodiments, the total length of all adhesive portions 14 on the front side of the first battery cell 12 along the first direction on an electrical connection line 11 is Q1, and the total length of all adhesive portions 14 on the back side of the second battery cell 13 along the first direction on an electrical connection line 11 is Q2, where Q1 > Q2. The front side of the battery cell experiences greater pressure when forming the assembly compared to the back side, and the front side is generally more susceptible to tension from the electrical connection line 11 than the back side. This arrangement strengthens the fixing effect of the electrical connection line 11 on the front side, balancing the yield, stability, and durability of the battery string. At the same time, the back side of the battery cell is generally less subjected to impact, which can reduce Q2, thereby saving adhesive material and improving the bifaciality.

[0093] In some embodiments, the length of an adhesive portion 14 on the battery body along the first direction is ≥0.5mm and ≤4mm. This configuration can further enhance the fixing effect of the adhesive portion 14 on the electrical connection wire 11, while also taking into account good light utilization and cost.

[0094] Optionally, the length of the adhesive portion 14 along the first direction may be, for example, 0.5 mm, 1 mm, 2 mm, 3 mm or 4 mm, or a range consisting of any two of the above values.

[0095] In some implementations, such as Figure 2As shown, the distance between the first front edge adhesive portion J1 and the second front edge adhesive portion J3 along the first direction is L4, and the distance between the first back edge adhesive portion J2 and the second back edge adhesive portion J4 along the first direction is L5, where L4 > L5. Similarly, setting L4 and L5 in this way helps to strengthen the fixing effect of the electrical connection wire 11 on the front side while reducing the amount of adhesive material used on the back side of the battery cell, thus saving costs and improving the bi-sided efficiency of the battery.

[0096] It should be noted that the distance of L4 can be understood as... Figure 2 As shown, the distance along the first direction between the end of the first front edge adhesive portion J1 closest to its adjacent battery edge 151 and the end of the second front edge adhesive portion J3 closest to its adjacent battery edge 151. The distance L5 can be understood as the distance along the first direction between the end of the first back edge adhesive portion J2 closest to its adjacent battery edge 151 and the end of the second back edge adhesive portion J4 closest to its adjacent battery edge 151.

[0097] In some implementations, such as Figure 1 or Figure 3 As shown, the distance L1 between the first front edge bonding portion J1 and the first back edge bonding portion J2 along the first direction satisfies the following condition with respect to the projected length W of the electrical connection line 11 in the first direction: W-44≤L1≤W-4 (unit: mm). This setting can enhance the bonding strength between the electrical connection line 11 and the battery cell while further reducing the risk of battery cell fragmentation and microcracks, thus maintaining the effectiveness of the module. If L1 is set too small, the connection strength between the electrical connection line 11 and the battery body will be limited, increasing the risk of poor soldering or detachment of the electrical connection line 11. If L1 is set too large, the bonding portion 14 at the end will be too close to the battery edge 151. After the adhesive material cures and forms the bonding portion 14, it is easy to become a stress concentration point. During the lamination process, it is easy to cause fragmentation and microcracks at the battery edge 151 due to stress concentration. At the same time, it leads to increased cost due to the use of more adhesive material and excessive shading of the battery cell, thus affecting the module power.

[0098] Optionally, L1 can be, for example, (W-44) mm, (W-40) mm, (W-35) mm, (W-30) mm, (W-25) mm, (W-20) mm, (W-15) mm, (W-10) mm, (W-5) mm, or (W-4) mm, or a range consisting of any two of the above values.

[0099] It should be noted that the distance of L1 can be understood as... Figure 3As shown, the distance along the first direction between the end of the first front edge adhesive portion J1 closest to its adjacent battery edge 151 and the end of the first back edge adhesive portion J2 closest to its adjacent battery edge 151. W can be understood as the maximum length covered by the orthographic projection of the electrical connection line 11 onto the surface of the battery cell in the battery string in the first direction.

[0100] In some embodiments, the distance along the first direction between the first front edge adhesive portion J1 and the second front edge adhesive portion J3 is L4, and L4 satisfies the following condition: -45≤L4≤ -4, unit mm. This configuration strengthens the bond between the electrical connection 11 and the first solar cell 12 while reducing the risk of breakage and microcracks in the first solar cell 12. If L4 > -4. The bonding portion 14 at the end is too close to the edge 151 of the battery, making the cured bonding portion 14 a stress concentration point. This can easily lead to fragmentation and microcracks at the edge 151 of the battery during lamination, and also increases the consumption of adhesive material. Furthermore, it increases the shading of the battery cell by the bonding portion 14, affecting the module power. If L4 < -45°C negatively impacts the bonding strength between the electrical connection wire 11 and the battery cell, increasing the risk of poor soldering or detachment of the electrical connection wire 11 due to thermal expansion and contraction or mechanical impact, thus negatively affecting the yield of the battery string.

[0101] Alternatively, L4 can be, for example, ( -45) mm, ( -40) mm, ( -35) mm, ( -30) mm, ( -25) mm, ( -20) mm, ( -15) mm, ( -10) mm, ( -5) mm or ( -4) mm, or a range consisting of any two of the above values.

[0102] In some embodiments, the length of the battery body along the first direction is P, where P-48 ≤ L4 ≤ P-8 (unit: mm). This configuration further strengthens the bond strength between the electrical connection wire 11 and the first battery cell 12, while avoiding risks such as poor soldering and detachment of the electrical connection wire 11. When L4 > P-8, the electrical connection wire 11 is fixed relatively rigidly, which greatly restricts the connection position between interconnected battery cells. This can easily cause stress concentration in the battery cells during battery string transportation and lamination, increasing the risk of fragmentation or microcracks at the edges of the battery cells. When L4 < P-48, it further affects the bond strength between the electrical connection wire 11 and the battery body, increasing the risk of poor soldering or detachment of the electrical connection wire 11 due to thermal expansion and contraction or mechanical impact, negatively impacting the yield of the battery string.

[0103] Optionally, L4 can be, for example, (P-48) mm, (P-40) mm, (P-35) mm, (P-30) mm, (P-25) mm, (P-20) mm, (P-15) mm, (P-10) mm, or (P-8) mm, or a range consisting of any two of the above values.

[0104] In some embodiments, the length P of the battery body along the first direction is ≥100mm and ≤200mm. For example, it can be 100mm, 105mm, 120mm, 140mm, 160mm, 180mm or 200mm, etc.

[0105] In some embodiments, the distance between the first back edge adhesive portion J2 and the second back edge adhesive portion J4 along the first direction is L5, and L5 satisfies the following condition: -45≤L5≤ -4, unit mm. This setting has a similar effect to L4, so I won't go into details.

[0106] Alternatively, L5 can be, for example, ( -45) mm, ( -40) mm, ( -35) mm, ( -30) mm, ( -25) mm, ( -20) mm, ( -15) mm, ( -10) mm, ( -5) mm or ( -4) mm, or a range consisting of any two of the above values.

[0107] In some implementations, the length of the battery body along the first direction is P, where P-48≤L5≤P-8, in mm. This setting has a similar effect to L4 and will not be elaborated further.

[0108] Optionally, L5 can be, for example, (P-48) mm, (P-40) mm, (P-35) mm, (P-30) mm, (P-25) mm, (P-20) mm, (P-15) mm, (P-10) mm, or (P-8) mm, or a range consisting of any two of the above values.

[0109] In some embodiments, as previously described, the electrical connection line 11 is suitable for connecting adjacent battery cells, for example, connecting the first battery cell 12 and the second battery cell 13. The distance between the end of the electrical connection line 11 and its nearest pad 17 is 2-6 mm. This arrangement helps to strengthen the connection between the electrical connection line 11 and the battery body.

[0110] Optionally, the distance between the end of the electrical connection 11 and its nearest pad 17 can be, for example, 2 mm, 3 mm, 4 mm, 5 mm or 6 mm, or a range consisting of any two of the above values.

[0111] In some embodiments, the distance between the end of the electrical connection 11 and its nearest battery edge 151 is 1 to 3 mm. This arrangement enhances the collection of edge current.

[0112] Optionally, the distance between the end of the electrical connection 11 and its nearest battery edge 151 can be, for example, 1 mm, 2 mm, or 3 mm, or a range between any two of the above values, preferably 2 mm.

[0113] In some embodiments, the adhesive portion 14 can be made of photocurable adhesive or thermosetting adhesive. The adhesive portion 14 has good adhesion, can effectively fix the electrical connection wire 11, and has good insulation properties. In photovoltaic modules, one or more adhesive portions 14 can be used to fix an electrical connection wire 11 as needed.

[0114] For example, forming the adhesive portion 14 on the electrical connection wire 11 by photopolymerization may include: providing a mesh template with a specific pattern and a plurality of through holes arranged at intervals on the template; placing the mesh template on the surface of the battery body such that the plurality of through holes correspond to the positions on the battery body where the adhesive portion 14 needs to be applied; performing screen printing to dispose of the adhesive material in the plurality of through holes to form an initial adhesive portion on the surface of the electrical connection wire 11 and the battery body; and then curing the initial adhesive portion to form the adhesive portion 14 by ultraviolet light.

[0115] In some embodiments, the projection of the adhesive portion 14 onto the surface of the battery body is any one of a rhombus or a rhombus-like shape, an ellipse or a ellipse-like shape; or the projection outline of the adhesive portion 14 onto the surface of the battery body is any one of a parabola-like shape or a cosine curve on one side of the electrical connection line 11 along the second direction. Such an adhesive shape can better achieve sufficient fixation of the electrical connection line 11.

[0116] Figure 4 A cross-sectional view of the adhesive portion in an embodiment of this application is shown. For example... Figure 4 As shown, the adhesive portion 14 has a contact area with the surface of the battery body, and the contact area has a first end and a second end (not shown in the figure) in a second direction; along the second direction, the distance between the first end or the second end of the adhesive portion 14 and the electrical connection line 11 is A, and the width of the electrical connection line 11 along the second direction is X, where A = aX, 2 ≤ a ≤ 8. This helps to save the cost of materials used in the adhesive portion 14 and improves the bonding yield between the electrical connection line 11 and the battery body.

[0117] For example, 'a' can be 2, 3, 4, 5, 6, 7, or 8, or a range consisting of any two of the above values.

[0118] In some embodiments, the width X of the electrical connection line 11 along the second direction is ≥0.1mm and ≤2mm. Within this width range, it is beneficial to achieve a better welding effect.

[0119] Optionally, the width X of the electrical connection line 11 along the second direction can be, for example, 0.1mm, 0.25mm, 0.5mm, 0.75mm, 1mm, 1.5mm or 2mm, or a range consisting of any two of the above values.

[0120] As mentioned above, the electrical connection wire 11 can have a cross-sectional area of ​​any shape. For example, taking a circular cross-sectional area as an example, the width X of the electrical connection wire 11 along the second direction can be understood as its diameter. Preferably, the diameter of the electrical connection wire 11 is ≥0.1mm and ≤0.4mm. More preferably, the diameter of the electrical connection wire 11 is ≥0.2mm and ≤0.3mm. Even more preferably, the diameter of the electrical connection wire 11 is ≥0.14mm and ≤0.28mm. This configuration enhances the connection effect between the electrical connection wire 11 and the battery cell.

[0121] Taking the cross-sectional area of ​​the electrical connection wire 11 as square as an example, the width X of the square electrical connection wire along the second direction is ≥0.5mm and X≤2mm; preferably, the width of the square electrical connection wire along the second direction is ≥0.5mm and X≤1mm.

[0122] In some implementations, such as Figure 4As shown, the distance between the two ends of the contact area in the first direction is T; the edge of the contact area has a contour line, and the area enclosed by the contour line and either side of the electrical connection line 11 is S; wherein, A is consistent with the previous description and will not be repeated here.

[0123] The area S can be understood as the area enclosed by the edge contour of the adhesive portion 14 on either side of the electrical connection line 11 along the second direction, on the surface of the battery body, and the boundary of the electrical connection line 11 projected perpendicular to the direction of the battery body. The edge contour can be obtained through image capture or other means. Setting the area S within the aforementioned range further ensures that the adhesive portion 14 provides sufficient fixation for the electrical connection line 11, improving the yield of the battery string; it also avoids waste of adhesive material. If the area S is too large, it will result in waste of adhesive material and may come into contact with adjacent current collectors, adversely affecting conductivity; if the area S is too small, it will not provide adequate fixation, and the electrical connection line 11 may detach, reducing the reliability of the connection between the electrical connection line 11 and the battery cell.

[0124] In some embodiments, the battery body includes an adjacent intermediate region and an edge region, with the edge region surrounding the intermediate region. An adhesive portion 14 located in the edge region is correspondingly disposed along a first direction or a second direction. For example... Figure 2 and Figure 3 As shown, this setup can be achieved using a uniform stencil, making the process relatively simple. The bonding portions 14 in the middle region are staggered along the second direction. Continuing as... Figure 2 and Figure 3 As shown, the bonding portions 14 in the middle region are staggered, allowing adjacent bonding portions 14 to fix different current collectors 16 respectively. This ensures that at different positions in the second direction, the bonding portions 14 fix different current collectors 16 to the electrical connection lines 11, reducing the risk of poor soldering and enhancing the current collection effect of the electrical connection lines 11 on the current collectors 16. In some embodiments, the thickness of the bonding portion 14 can be greater than the thickness of the electrical connection lines 11 in the direction perpendicular to the surface of the battery body. This arrangement provides better coverage of the electrical connection lines 11, especially during high and low temperature cycling, enhancing the welding effect between the electrical connection lines 11 and the current collectors 16 and improving the battery string yield.

[0125] In other embodiments, the thickness of the adhesive portion 14 is less than the thickness of the electrical connection wire 11 in a direction perpendicular to the surface of the battery body. This arrangement ensures that the electrical connection wires are in direct contact with the adhesive film during the lamination process, resulting in uniform heat conduction and a better lamination effect.

[0126] This application also provides a photovoltaic module comprising a plurality of any of the aforementioned cell strings. This photovoltaic module has the same or similar beneficial effects as any of the aforementioned cell strings, which will not be elaborated further here.

[0127] In some embodiments, any of the aforementioned cells are connected in series to form a solar cell string, and an encapsulation structure is placed around the periphery of the solar cell string to form a photovoltaic module.

[0128] In some implementations, the encapsulation structure may include a backsheet, an encapsulating film, a glass panel, etc., to improve the stability of the solar cell string. The glass panel is located on the front of the solar cell string, and the backsheet is located on the back of the solar cell string, both serving a protective function. The adhesive film is the adhesive film between the solar cell string and the glass panel and backsheet, serving to bond and fix the string; it can be made of a transparent material.

[0129] In photovoltaic modules, the electrical connection lines of adjacent preceding cells have opposite polarities to the electrical connection lines of connected following cells in order to achieve current transmission.

[0130] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. 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 battery string, characterized in that, include: At least one unit in series; The series unit includes: an electrical connection wire, a first battery cell and a second battery cell adjacent to each other in the extension direction of the electrical connection wire, and a plurality of adhesive portions disposed on the electrical connection wire; Both the first and second battery cells include a battery body, which includes: a battery edge and opposing front and back sides; the electrical connection wire is electrically connected to the front side of the first battery cell and the back side of the second battery cell; the plurality of adhesive portions include a plurality of front adhesive portions located on the front side and a plurality of back adhesive portions located on the back side. The battery edge includes: a chamfered edge with a chamfer and a cut edge without a chamfer formed by cutting, and the chamfered edge and the cut edge on the battery body are opposite to each other; in the series unit, the chamfered edge of the first battery cell and the cut edge of the second battery cell are adjacent to each other; Along the extension direction of the electrical connection line, in the first battery cell: the distance between the first front edge bonding portion J1, which is furthest from the second battery cell, and its adjacent cut edge is S1; the distance between the second front edge bonding portion J3, which is adjacent to the second battery cell, and its adjacent chamfer edge is S3; in the second battery cell: the distance between the first back edge bonding portion J2, which is furthest from the first battery cell, and its adjacent chamfer edge is S2; the distance between the second back edge bonding portion J4, which is adjacent to the first battery cell, and its adjacent cut edge is S4. Where S1 > S3, and / or S4 > S2.

2. The battery string according to claim 1, characterized in that, S1 > S2, and / or, S3 < S4.

3. The battery string according to claim 1, characterized in that, S1-S2≤5mm, preferably less than 3mm; And / or, S1-S3≤5mm, preferably less than 3mm; And / or, S4-S2≤5mm, preferably less than 3mm.

4. The battery string according to any one of claims 1-3, characterized in that, S1 > S4, and / or, S3 < S2.

5. The battery string according to any one of claims 1-4, characterized in that, The front bonding portions on the first battery cell and the second battery cell are the same, and the back bonding portions on the first battery cell and the second battery cell are the same; And / or, the series unit includes a plurality of electrical connection lines, wherein the first front edge adhesive portion J1, the second front edge adhesive portion J3, the first back edge adhesive portion J2, or the second back edge adhesive portion J4 on the plurality of electrical connection lines are arranged in a straight line extending in the second direction.

6. The battery string according to any one of claims 1-5, characterized in that, A solder pad is provided between the electrical connection wire and the battery body. The solder pad includes a first front edge solder pad provided between the first front edge bonding portion J1 and its adjacent cut edge, a second front edge solder pad provided between the second front edge bonding portion J3 and its adjacent chamfer edge, a first back edge solder pad provided between the first back edge bonding portion J2 and its adjacent chamfer edge, and a second back edge solder pad provided between the second back edge bonding portion J4 and its adjacent cut edge. Wherein, the distance between the second front edge bonding portion J3 and the second back edge bonding portion J4 is L2, and the distance between the second front edge pad and the second back edge pad is L3, where L3≤L2≤5*L3.

7. The battery string according to any one of claims 1-5, wherein, On the first and second battery cells, the total length of all adhesive portions on the electrical connection line along the first direction is Q, and the projected length of the electrical connection line in the first direction is W, wherein 2.5% ≤ Q / W ≤ 48.5%; Preferably, the projections of the first and second solar cells in the first direction overlap, with 2.5% ≤ Q / W ≤ 32.5%; Preferably, the projections of the first and second solar cells in the first direction do not overlap, and 4.5%≤Q / W≤48.5%.

8. The battery string according to any one of claims 1-5, wherein, The sum of the lengths of all adhesive portions on the front side of the first battery cell along the first direction on the electrical connection line is Q1, and the sum of the lengths of all adhesive portions on the back side of the second battery cell along the first direction on the electrical connection line is Q2, where Q1 > Q2; and / or, The distance between the first front edge adhesive portion J1 and the second front edge adhesive portion J3 along the first direction is L4, and the distance between the first back edge adhesive portion J2 and the second back edge adhesive portion J4 along the first direction is L5, wherein L4 > L5.

9. The battery string according to any one of claims 1-5, wherein, The distance between the first front edge adhesive portion J1 and the first back edge adhesive portion J2 along the first direction is L1, and the projected length of the electrical connection line in the first direction is W, where W-44≤L1≤W-4, in mm; And / or, the distance between the first front edge adhesive portion J1 and the second front edge adhesive portion J3 along the first direction is L4, the distance between the first back edge adhesive portion J2 and the second back edge adhesive portion J4 along the first direction is L5, the projected length of the electrical connection wire in the first direction is W, and the length of the battery body along the first direction is P. in, -45≤L4≤ -4, And / or, -45≤L5≤ -4, And / or, P-48≤L4≤P-8, And / or, P-48≤L5≤P-8, unit mm.

10. A photovoltaic module comprising a battery string as described in any one of claims 1-9.

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