A back contact cell assembly and a photovoltaic system

Abstract

The application relates to the technical field of solar cells, and particularly discloses a back contact cell assembly, which comprises a first cell piece, the back surface of the first cell piece is provided with a plurality of alternately arranged first welding strips and second welding strips, and the first welding strips are connected through bus bars; wherein the first welding strip comprises a body section, a turning section and a welding section which are sequentially connected, the welding section is turned by 120-240 degrees relative to the body section through the turning section; and the welding section at least partially overlaps with the bus bar to be welded with the bus bar. According to the application, the turning of the free end can be realized through the turning section, the space for placing the bus bar is not needed to be reserved between the cell pieces, the adjacent cell pieces are more closely arranged, the thickness is more uniform, and the risk of cell piece breakage is reduced.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more particularly to a back-contact battery module and a photovoltaic system. Background Technology

[0002] Back-contact solar modules typically consist of an array of back-contact solar cells, comprising several strings of back-contact cells. In back-contact solar modules, edge busbars are usually located at the edges of the module, while center busbars are typically located in the center. Both require a certain amount of space to be reserved on the module. This reduces the effective light-receiving area of ​​the module, affecting its conversion efficiency and also its aesthetics.

[0003] To improve the effective light-receiving area and aesthetics of back-contact battery modules, existing technologies have placed the busbars on the back of the cells. However, this approach has encountered problems such as high microcrack and cell breakage rates in actual production. The root cause is that the solder ribbons of the end cells need to extend to the back busbars, causing the solder ribbons and busbars to overlap vertically, resulting in a large stacking height. During the lamination process, this overlapping area forms stress concentration points due to abrupt changes in thickness, which can easily cause microcracks or even breakage in brittle cells, ultimately leading to an increased module breakage rate and a decreased yield. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a back-contact battery module and a photovoltaic system that can utilize a steering segment to achieve steering of the free end, eliminating the need to reserve space between battery cells for placing busbars, resulting in a more compact arrangement of adjacent battery cells, more uniform thickness, and reduced risk of breakage.

[0005] To solve the above-mentioned technical problems, embodiments of the present invention provide a back contact battery assembly, including a first battery cell, wherein the back side of the first battery cell is provided with a plurality of alternating first and second solder strips, and the first solder strips are connected by a busbar; The first welding strip includes a body segment, a turning segment, and a welding segment connected in sequence. The welding segment turns 120-240 degrees relative to the body segment via the turning segment. The vertical projections of the body segment, the turning segment, and the welding segment onto the front of the first battery cell are located on the first battery cell. The welding segment at least partially overlaps with the busbar for welding to the busbar.

[0006] As an improvement to the above scheme, the length of the welded segment is denoted as... The length of the steering section is The radian steering angle of the steering segment is... The distance between adjacent body segments is W, which satisfies the following formula:

[0007] .

[0008] As an improvement to the above scheme, the length of the turning segment in the extension direction of the body segment is 0.1 to 2 times the length of the welding segment.

[0009] As an improvement to the above scheme, the ratio of the length of the welding section to the length of the body section is 0.01-0.8.

[0010] As an improvement to the above solution, it also includes several battery strings, each battery string comprising a first battery cell and a second battery cell adjacent to each other along a first direction. The first and second solder strips are alternately arranged along a second direction. The back of the second battery cell is provided with a third and a fourth solder strip alternately arranged along the second direction. The first solder strip corresponds one-to-one with the third solder strip, and the second solder strip corresponds one-to-one with the fourth solder strip. The second direction intersects the first direction. The first solder strip is electrically connected to the third solder strip, or the second solder strip is electrically connected to the fourth solder strip. The busbar is arranged along the second direction.

[0011] As an improvement to the above solution, the steering segment includes a first steering segment and a second steering segment. The body segment, the first steering segment, the second steering segment and the welding segment are connected in sequence. Both the first steering segment and the second steering segment are arc-shaped. The first steering segment is an arc with a radius of R, and the second steering segment is an arc with a radius of r, where R>r.

[0012] As an improvement to the above solution, the welding section is parallel to the body section.

[0013] As an improvement to the above solution, the distance between the welding segment and the adjacent second welding strip is equal to the distance between the welding segment and the corresponding body.

[0014] As an improvement to the above solution, the first battery cell is provided with several adhesive dots for pre-fixing the first welding strip, and the starting point of the turning segment is provided with turning positioning adhesive dots.

[0015] As an improvement to the above solution, the first steering segment is located in a plane parallel to the surface of the first battery cell, and the second steering segment gradually rises in the thickness direction of the first battery cell.

[0016] As an improvement to the above solution, the first battery cell is located at the end of the corresponding battery string, the busbar is disposed on the first battery cell and located on the side away from the second battery cell; the second welding strip is electrically connected to the fourth welding strip; the turning section extends from the end of the body section away from the second battery cell and is connected to the busbar through the welding section.

[0017] As an improvement to the above solution, the back contact battery assembly includes at least one first parallel battery string group, the first parallel battery string group including a first battery string and a second battery string arranged along the first direction. The first battery cell is located at the end of the first battery string, and the second battery cell is located at the end of the second battery string, with the first and second battery cells adjacent to each other; the busbar is disposed on the first battery cell and located on the side away from the second battery cell; the first solder strip is electrically connected to the third solder strip; the deflection section extends from the end of the body section away from the second battery cell and is connected to the busbar through the soldering section; the second solder strip extends outward from the side of the first battery cell away from the second battery cell and is connected to another battery cell.

[0018] As an improvement to the above solution, the back contact battery assembly includes at least one second parallel battery string group, the second parallel battery string group including a first battery string and a second battery string arranged along the first direction. The first battery cell is located at the end of the first battery string, the second battery cell is located at the end of the second battery string, and the first and second battery cells are adjacent to each other; the third welding strip has a bent section and an extended section; The busbar is disposed on the first battery cell and located on the side close to the second battery cell; the welding section is located on one side of the body section and connected to the busbar; the extension section is offset from the first welding strip in the first direction through the bending section and connected to the busbar on the other side of the body section.

[0019] As an improvement to the above solution, an insulating strip is also included, which is disposed between the busbar and the first battery cell, and the body segment and the second welding strip are insulated and isolated from the busbar by the insulating strip.

[0020] As an improvement to the above solution, the back contact battery assembly includes at least one third parallel battery string group, the third parallel battery string group including two battery strings arranged along the second direction; wherein, in the same second parallel battery string group, the same bus bar extends from the first battery cell in one battery string to the first battery cell in the other battery string to connect the two battery strings in the parallel battery string group in parallel.

[0021] As an improvement to the above solution, an insulating strip is also included, which is disposed between the busbar and the first battery cell. The body segment and the second solder strip are insulated and isolated from the busbar by the insulating strip. The insulating strip extends along the busbar from the first battery cell in one battery string to the first battery cell in another battery string.

[0022] As an improvement to the above solution, the insulating strip has periodically arranged recesses, and the busbar is attached to the surface of the insulating strip to form a concave-convex structure, wherein the recessed positions of the concave-convex structure are used to accommodate the welding segment.

[0023] Accordingly, embodiments of the present invention also provide a photovoltaic system, including a back contact battery module as described above.

[0024] Implementing the embodiments of the present invention has the following beneficial effects: The above scheme, by setting the first welding strip as a body segment, a turning segment, and a welding segment connected in sequence, utilizes the body segment to contact the battery cell and the turning segment to achieve the turning of the free end. While ensuring the connection length between the body segment and the battery cell, a welding segment is formed on the surface of the first battery cell. Finally, the welding segment is welded to the busbar, converging and transmitting the electrical energy of the first welding strip. This saves space, eliminating the need to reserve space between battery cells for busbars, resulting in a closer arrangement of adjacent battery cells, more uniform thickness, and reduced risk of fragmentation. The first welding strip is entirely protected by the first battery cell and will not leave the area directly above the first battery cell, making the connection between the first welding strip and the busbar more reliable. Because adjacent battery cells are arranged more closely, the suspension distance of the welding strip passing through different battery cells is shorter, reducing the probability of breakage due to bending or other reasons at the suspension point of the welding strip, thus improving the reliability of the back-contact battery module.

[0025] The welding segment is rotated 120-240 degrees relative to the body segment via the turning segment, which is equivalent to a bending process. During the turning process, the welding segment naturally forms an arc-shaped turning segment with a smooth trajectory, making it less likely to damage the first weld strip due to the turning. The welding segment is connected to the busbar, with the welding segment at least partially overlapping the busbar for welding. This ensures sufficient connection area between the first weld strip and the busbar, reducing the resistance at the connection point and thus lowering the overall resistance of the back contact battery assembly, thereby improving the photoelectric conversion output efficiency of the back contact battery assembly. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a back contact battery assembly according to an embodiment of the present invention; Figure 2 yes Figure 1 Enlarged view of part A; Figure 3 This is a schematic diagram showing the dimensional relationship between the first solder strip and the busbar of a back contact battery assembly according to an embodiment of the present invention; Figure 4 yes Figure 1 Enlarged view of part D; Figure 5 yes Figure 1 Enlarged view of part B; Figure 6 yes Figure 1 Enlarged view of part C; Figure 7 This is a partial structural enlarged view of a back contact battery assembly according to the second embodiment of the present invention; Figure 8 This is a schematic diagram of a back-contact battery assembly according to the seventh embodiment of the present invention; Figure 9 This is a schematic diagram showing the positional relationship between the first solder strip, the busbar, and the insulating strip in the eighth embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It is hereby declared that the directional terms such as up, down, left, right, front, back, inside, and outside used in this text are based solely on the accompanying drawings and are not intended to specifically limit the invention.

[0028] The photovoltaic system in this application embodiment may include at least one back-contact battery module as described in this application embodiment. In the photovoltaic system, the back-contact battery modules can be electrically connected in parallel or in series, depending on actual needs. In the embodiments of this application, 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.

[0029] Example 1 like Figure 1 and Figure 2 As shown, this embodiment provides a back contact battery assembly, including a first battery cell 100. The back of the first battery cell 100 is provided with a plurality of alternating first solder strips 1 and second solder strips 2. The first solder strips 1 are connected by a busbar 3. The first welding strip 1 includes a body segment 11, a turning segment 12, and a welding segment 13 connected in sequence. The welding segment 13 is turned 120-240 degrees relative to the body segment 11 by the turning segment 12. The vertical projection of the body segment 11, the turning segment 12, and the welding segment 13 onto the front of the first battery cell is located on the first battery cell 100. The welding segment 13 at least partially overlaps with the busbar 3 to be welded to the busbar 3.

[0030] The above scheme, by setting the first welding strip 1 as a body segment 11, a turning segment 12, and a welding segment 13 connected in sequence, utilizes the body segment 11 to contact the battery cell, and utilizes the turning segment 12 to achieve the turning of the free end. While ensuring the connection length between the body segment 11 and the battery cell, a welding segment 13 is formed on the surface of the first battery cell 100. Finally, the welding segment 13 is welded to the busbar 3 to gather and send out the electrical energy of the first welding strip 1. This saves space, eliminating the need to reserve space between battery cells for placing the busbar 3. Adjacent battery cells are arranged more closely, avoiding overlap between different welding strips, resulting in more uniform thickness and reducing the risk of fragmentation. The first welding strip 1 is entirely protected by the first battery cell 100 and will not leave the area directly above the first battery cell 100, making the connection between the first welding strip 1 and the busbar 3 more reliable. Because adjacent battery cells are arranged more closely, the suspension distance of the welding strip passing through different battery cells is shortened, reducing the probability of breakage of the suspended part of the welding strip due to bending or other reasons, thus improving the reliability of the back contact battery module.

[0031] Preferably, combined with Figure 3 As shown, the length of the welded segment is denoted as . The length of the steering section is The radian steering angle of the steering segment is... The distance between adjacent body segments is W, which satisfies the following formula:

[0032] .

[0033] Under the condition of satisfying the above formula, the length of the welding section can be controlled according to the length of the turning section and the turning angle of the welding section, so as to ensure the length of the welding section and the welding area between the welding section and the busbar, increase the effective contact area, and reduce the contact resistance. At the same time, since the welding point is staggered from the welding strip body, the heat during welding will not be directly transferred to the insulation layer of the welding strip body, thus avoiding thermal aging failure of the insulation layer.

[0034] This embodiment includes several battery strings, each battery string comprising a first battery cell 100 and a second battery cell 200 adjacent to each other along a first direction. The first solder strip 1 and the second solder strip 2 are alternately arranged along a second direction. The back of the second battery cell 200 is provided with a third solder strip 4 and a fourth solder strip 5 alternately arranged along the second direction. The first solder strip 1 corresponds one-to-one with the third solder strip 4, and the second solder strip 2 corresponds one-to-one with the fourth solder strip 5. The second direction intersects the first direction. The first solder strip 1 and the third solder strip 4 are electrically connected, or the second solder strip 2 and the fourth solder strip 5 are electrically connected. The busbar 3 is arranged along the second direction. Specifically, the first solder strip 1 and the third solder strip 4 can be integrally formed to achieve electrical connection; the second solder strip 2 and the fourth solder strip 5 can be integrally formed to achieve electrical connection, thereby forming a complete conductive circuit. The first battery cell 100 and the second battery cell 200 are connected in series in the above manner.

[0035] The welding segment 13 is rotated 120-240 degrees relative to the body segment 11 via the turning segment 12. Compared to the bending process, the turning segment 13 naturally forms an arc-shaped turning segment 12 during the turning process relative to the body segment 11, resulting in a smooth path and reducing the likelihood of damage to the first weld strip 1 due to the turning. The welding segment 13 is connected to the busbar 3, with the welding segment 13 at least partially overlapping the busbar 3 for welding. This ensures sufficient connection area between the first weld strip 1 and the busbar 3, reducing the resistance at the connection point and thus lowering the overall resistance of the back contact battery assembly, thereby improving the photoelectric conversion output efficiency of the back contact battery assembly.

[0036] In some specific embodiments, the space occupied by the steering segment 12 is limited. Specifically, the length of the steering segment 12 in the extension direction of the body segment 11 is 0.1 to 2 times the length of the welding segment 13. It should be noted that this embodiment limits the ratio between the length of the steering segment 12 in the extension direction of the body segment 11 and the length of the welding segment 13. In the extreme case, when the length of the steering segment 12 in the extension direction of the body segment 11 is twice the length of the welding segment 13, that is, the length h of the steering segment 12 in the extension direction of the body segment 11 is equal to twice the length H of the welding segment 13, the steering segment 12 has a larger steering space, avoiding stress concentration in the steering segment 12 and reducing production difficulty. When the length of the steering segment 12 in the extension direction of the body segment 11 exceeds twice the length of the welding segment 13, the space occupied by the steering segment 12 is too large, which will affect the contact length between the body segment 11 and the first battery cell 100. When the length of the turning segment 12 in the extension direction of the body segment 11 is 0.1 times the length of the welding segment 13, the turning radius of the turning segment 12 is small, which can make full use of the space near the edge of the first battery cell 100. When the length of the turning segment 12 in the extension direction of the body segment 11 is less than 0.1 times the length of the welding segment 13, the turning radius of the turning segment 12 is too small, which makes it easy to break during the turning process. The battery cell is at risk of developing microcracks due to stress concentration during welding and subsequent use, which affects the reliability of the connection.

[0037] In addition, in some embodiments, the ratio of the length of the welding segment 13 to the length of the body segment 11 is limited to between 0.01 and 0.8. The length of the welding segment 13 limits its connection area with the busbar 3, while the length of the body segment 11 affects whether the photogenerated carriers of the first solar cell 100 can be smoothly sent out. Limiting the length of the welding segment 13 to the length of the body segment 11 to between 0.01 and 0.8 allows the length of the welding segment 13 to be reasonably set according to the length of the body segment 11, so that the welding segment 13 can be reliably welded to the busbar 3 while controlling the cost of the welding segment 13. The welding segment 13 can withstand the reset stress that may exist in the steering segment 12 for a long time.

[0038] Preferably, the turning segment 12 can be turned 180 degrees relative to the body segment 11, making the welding segment 13 parallel to the body segment 11. Setting the welding segment 13 parallel to the body segment 11 ensures that the distance between the welding segment 13 and the body segment 11 is consistent throughout, preventing the welding segment 13 from being too close to the body segment 11 due to tilting. This would reduce the insulation between the busbar 3 and the body segment 11 or the first battery cell 100 during or after welding, thus affecting the working stability of the battery cell.

[0039] More preferably, while maintaining the parallelism between the welding segment 13 and the body segment 11, the distance between the welding segment 13 and the adjacent second weld strip 2 can be equal to the distance between the welding segment 13 and the corresponding body segment. That is, the welding segment 13 is located exactly in the middle of the body segment 11 and the second weld strip 2, and the welding segment 13 can be kept as far away from the body segment 11 and the second weld strip 2 as possible, leaving sufficient space for welding the welding segment 13 to the busbar 3.

[0040] Preferably, an insulating strip 6 is further provided between the busbar 3 and the first battery cell 100, and the body segment 11 and the second welding strip 2 are insulated and isolated from the busbar 3 by the insulating strip 6. The insulating strip 6 can be an insulating adhesive, or a non-conductive tape or insulating film, such as a PET or PI tape with acrylic or silicone, or a PET or PI substrate coated with ethylene-vinyl acetate copolymer or hot melt adhesive on one or both sides. It is understood that the insulating strip 6 may contain ethylene-vinyl acetate copolymer, resin materials, polyimide, polypropylene, or polyethylene, and may also contain an acrylic adhesive layer. It should be noted that the thickness of the insulating strip 6 cannot be too thick or too thin. If the insulating strip 6 is too thin, it is inconvenient to operate during pasting, easily deformed by pulling, and there is a risk of breakage during long-term insulation. If it is too thick, it will increase the height difference, and the stress generated during the lamination process will be large, which will easily cause fragmentation and increase the risk of poor soldering. Based on this, in the embodiments of this application, the thickness of the insulating strip 6 can be set between 0.05mm and 0.8mm. Thus, the insulating strip 6 is neither too thin nor too thick. For example, the thickness of the insulating strip 6 can be 0.05mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, or 0.8mm. The width of the insulating strip 6 (i.e., its length in the first direction) is greater than or equal to the width of the busbar 3 (i.e., its length in the first direction). In this way, the insulating strip 6 can provide complete insulation between the busbar 3 and the second solder strip 2 and the fourth solder strip 5 on the second battery cell 200.

[0041] Example 2 Combination Figure 7 and Figure 9As shown, this embodiment differs from the first embodiment in that the shape of the steering segment 12 in this embodiment is more precisely controlled. Specifically, the steering segment 12 includes a first steering segment 121 and a second steering segment 122. The body segment 11, the first steering segment 121, the second steering segment 122, and the welding segment 13 are connected sequentially. Both the first steering segment 121 and the second steering segment 122 are arc-shaped. The first steering segment 121 is an arc with a radius of R, and the second steering segment 122 is an arc with a radius of r, where R>r. The first steering segment 121 bends from the end of the body segment 11, resulting in concentrated bending stress, which can easily damage the welding strip during bending. By setting the first steering segment 121 with a larger radius, the welding strip can be protected within a limited space, and the body segment 11 can be prevented from being pulled by the first steering segment 121, thus avoiding potential problems such as poor welding between the body segment 11 and the first battery cell 100. The second steering segment 122 with a smaller radius can utilize the limited remaining space for turning, completing a near 180-degree turn of the welding segment 13 relative to the body segment 11.

[0042] In some embodiments, in addition to designing the structure of the steering segment 12 in the horizontal plane, variations are also made in the thickness direction of the first battery cell 100. Specifically, the first steering segment 121 is located in a plane parallel to the surface of the first battery cell 100, and the second steering segment 122 gradually rises in the thickness direction of the first battery cell 100. It should be noted that by placing the first steering segment 121 in a plane parallel to the surface of the first battery cell 100, the first steering segment 121 can be kept close to the surface of the first battery cell 100. By setting the second steering segment 122 to gradually rise in the thickness direction of the first battery cell 100, the welding segment 13 can be positioned precisely at the height level of the busbar 3, facilitating a reliable connection between the welding segment 13 and the busbar 3. Preferably, the first steering segment 121 bears 50% of the steering angle of the steering segment, and the second steering segment 122 bears the other 50% of the steering angle, working together to form a rotating structure connecting the welding segment 13 and the body segment 11.

[0043] Example 3 like Figure 7 As shown, in this embodiment, the first battery cell 100 is provided with several adhesive dots for pre-fixing the first welding strip 1, and the starting point of the steering segment 12 is provided with steering positioning adhesive dots 7. By setting the steering positioning adhesive dots 7 at the starting point of the steering segment 12, the starting point of the steering segment 12 can be fixed to the first battery cell 100, preventing the suspended steering segment 12 from pulling on the body segment 11 during welding or transportation, thus affecting the connection reliability between the body segment 11 and the first battery cell 100.

[0044] Example 4 This embodiment illustrates one possible position of the first battery cell 100 in a single battery string, as proposed in this application. The first battery cell 100 is located at the end of the corresponding battery string. The busbar 3 is disposed on the first battery cell 100 and located on the side away from the second battery cell 200. The second solder strip 2 is electrically connected to the fourth solder strip 5. The turning section 12 extends from the end of the body section 11 away from the second battery cell 200 and is connected to the busbar 3 through the welding section 13. That is, in this embodiment, the first battery cell 100 is located as the first or last battery cell in the battery string arranged sequentially. In this case, the busbar 3 is usually referred to as the edge busbar. The second battery cell 200 is connected in series with the third solder strip 4 of the first battery cell 100 through the fourth solder strip 5. The first solder strip 1 draws the current generated by this battery string into the busbar 3. Figure 2 This assumes that the first solar cell 100 is at the beginning of the solar cell string. Figure 4 This refers to the case where the first battery cell 100 is located at the end of the battery string. In this state, the width of the first battery cell 100 is relatively small, and the ratio of the length of the welding segment 13 to the length of the body segment 11 is limited to between 0.01 and 0.4.

[0045] Example 5 Combination Figure 5 As shown, the back contact battery assembly of this embodiment includes at least one first parallel battery string group, the first parallel battery string group including a first battery string and a second battery string arranged along the first direction. The first battery cell 100 is located at the end of the first battery string, and the second battery cell 200 is located at the end of the second battery string, with the first battery cell 100 and the second battery cell 200 adjacent to each other. The busbar 3 is disposed on the first battery cell 100 and located on the side away from the second battery cell 200. The first solder strip 1 is electrically connected to the third solder strip 4. The turning section 12 extends from the end of the body section 11 away from the second battery cell 200 and is connected to the busbar 3 through the welding section 13. The second solder strip 2 extends outward from the side of the first battery cell 100 away from the second battery cell 200 and is connected to another battery cell. In this embodiment, two or more battery strings are connected in parallel in a first direction, which can provide a larger current output under the same illumination conditions. The busbar 3 is located on the first battery cell 100 and on the side away from the second battery cell 200, which can keep it away from the adjacent positions of different battery strings, avoiding damage to the busbar 3 in case of accidental relative displacement of different battery strings.

[0046] Example 6 Combination Figure 6As shown, the back contact battery assembly in this embodiment includes at least one second parallel battery string group, which includes a first battery string and a second battery string arranged along the first direction. The first battery cell 100 is located at the end of the first battery string, the second battery cell is located at the end of the second battery string, and the first battery cell 100 and the second battery cell 200 are adjacent to each other; the third welding strip 4 has a bent section 21 and an extended section 22. The busbar 3 is disposed on the first battery cell 100 and located on the side close to the second battery cell 200; the welding section 13 is located on one side of the body section 11 and connected to the busbar 3; the extension section 22 is offset from the first welding strip 1 in the first direction through the bending section 21 and connected to the busbar 3 on the other side of the body section 11.

[0047] It should be noted that in this embodiment, the busbar 3 is disposed on the first battery cell 100 and located on the side close to the second battery cell 200. The welding section 13 is located on one side of the body section 11 and connected to the busbar 3. A bent section 21 and an extension section 22 are cleverly provided on the third welding strip 4 to connect the two battery strings in parallel in the first direction with the shortest welding strip length. Similar to embodiment 5, the busbar 3 here is generally referred to as the middle busbar 3. Using this embodiment, two sets of battery strings can be connected in parallel on a single busbar 3. The welding section 13 and the extension section 22 are separated by the body section 11 of the first welding strip 1, and there are no overlapping welding strips at the welding position, ensuring welding reliability. In this state, the width of the first battery cell 100 is relatively large, and the ratio of the length of the welding section 13 to the length of the body section 11 is limited to between 0.03 and 0.8.

[0048] Example 7 like Figure 8 As shown, the back-contact battery assembly includes at least one third parallel battery string group, which includes two battery strings arranged along the second direction. Within the same second parallel battery string group, the same busbar 3 extends from the first cell 100 of one battery string to the first cell 100 of the other battery string to connect the two battery strings in parallel. This embodiment connects the battery strings in parallel in the second direction. Combined with embodiments 5 and 6, it enables arbitrary expansion of the battery cells within a planar range, meeting the needs of photovoltaic systems with different power outputs and application scenarios.

[0049] Preferably, in this embodiment, an insulating strip 6 is further provided between the busbar 3 and the first battery cell 100, and the body segment 11 and the second welding strip 2 are insulated and isolated from the busbar 3 by the insulating strip 6; the insulating strip 6 extends along the busbar 3 from the first battery cell in one battery string to the first battery cell in another battery string.

[0050] More preferably, the insulating strip 6 has periodically arranged recesses 61, and the busbar 3 is pressed against the surface of the insulating strip 6 to form a concave-convex structure 31. The recessed positions of the concave-convex structure 31 are used to accommodate the welding section 13. By designing the recesses of the insulating strip 6 and cooperating with the corresponding back pressure process to form the concave-convex structure 31 of the busbar 3, and arranging the welding section 13 and / or the extension section 22 in the concave-convex structure of the busbar 3, the welding point can be accommodated in the concave-convex structure and protected by the concave-convex structure. On the one hand, it can avoid the welding point from loosening due to bumps or other reasons during transportation or installation; on the other hand, it can reduce the overall thickness of the battery cell, reduce the space occupied by the battery cell, and make it more widely applicable.

[0051] Example 8 This invention also provides a photovoltaic system, including the back contact battery module as described above.

[0052] A photovoltaic system employing the back-contact battery module described in the above embodiment utilizes a first solder strip 1 configured as a body segment 11, a turning segment 12, and a welding segment 13 connected in sequence. The body segment 11 contacts the battery cell, and the turning segment 12 enables the free end to turn. While maintaining the connection length between the body segment 11 and the battery cell, a welding segment 13 is formed on the surface of the first battery cell 100. Finally, the welding segment 13 is welded to the busbar 3, converging and transmitting the electrical energy from the first solder strip 1. This saves space, eliminating the need to reserve space between battery cells for the busbar 3, allowing for a more compact arrangement of adjacent battery cells and a larger battery cell area per unit area. The first solder strip 1 is entirely protected by the first battery cell 100 and does not leave the area directly above the first battery cell 100, making the connection between the first solder strip 1 and the busbar 3 more reliable. Because adjacent battery cells are arranged more closely, the suspension distance of the solder strip passing through different battery cells is shortened, reducing the probability of breakage due to bending or other reasons at the suspension point, thus improving the overall reliability of the photovoltaic system.

[0053] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A back-contact battery assembly, characterized in that, It includes a first battery cell, and the back of the first battery cell is provided with a plurality of alternating first and second solder strips, the first solder strips being connected by a busbar; The first welding strip includes a body segment, a turning segment, and a welding segment connected in sequence. The welding segment turns 120-240 degrees relative to the body segment via the turning segment. The welding segment at least partially overlaps with the busbar for welding to the busbar. The steering segment includes a first steering segment and a second steering segment. The body segment, the first steering segment, the second steering segment, and the welding segment are connected in sequence. Both the first steering segment and the second steering segment are arc-shaped. The first steering segment is located in a plane parallel to the surface of the first battery cell, and the second steering segment gradually rises in the thickness direction of the first battery cell. Let the length of the welded segment be . The length of the steering section is The radian steering angle of the steering segment is... The distance between adjacent body segments is W, which satisfies the following formula: 。 2. The back contact battery assembly as described in claim 1, characterized in that, The vertical projections of the body section, the turning section, and the welding section onto the front of the first battery cell are located on the first battery cell.

3. The back contact battery assembly as described in claim 1, characterized in that, The length of the turning segment in the extension direction of the body segment is 0.1 to 2 times the length of the welding segment.

4. The back contact battery assembly as described in claim 1, characterized in that, The ratio of the length of the welded section to the length of the body section is 0.01-0.

8.

5. The back contact battery assembly as described in claim 1, characterized in that, It also includes several battery strings, each battery string comprising a first battery cell and a second battery cell adjacent to each other along a first direction. The first and second solder strips are alternately arranged along a second direction. The back of the second battery cell is provided with a third and a fourth solder strip alternately arranged along the second direction. The first solder strip corresponds one-to-one with the third solder strip, and the second solder strip corresponds one-to-one with the fourth solder strip. The second direction intersects the first direction. The first solder strip is electrically connected to the third solder strip, or the second solder strip is electrically connected to the fourth solder strip. The busbar is arranged along the second direction.

6. The back contact battery assembly as claimed in claim 1, characterized in that, The first turning segment is an arc with radius R, and the second turning segment is an arc with radius r, where R > r.

7. The back contact battery assembly as described in any one of claims 1-6, characterized in that, The welded section is parallel to the body section.

8. The back contact battery assembly as claimed in claim 7, characterized in that, The distance between the welded segment and the adjacent second weld strip is equal to the distance between the welded segment and the corresponding body.

9. The back contact battery assembly as described in any one of claims 1-6, characterized in that, The first battery cell has several adhesive dots for pre-fixing the first welding strip, and the starting point of the steering segment has steering positioning adhesive dots.

10. The back contact battery assembly as claimed in claim 5, characterized in that, The first battery cell is located at the end of the corresponding battery string, and the busbar is disposed on the first battery cell and located on the side away from the second battery cell; the second welding strip is electrically connected to the fourth welding strip; the turning section extends from the end of the body section away from the second battery cell and is connected to the busbar through the welding section.

11. The back contact battery assembly as claimed in claim 5, characterized in that, The back contact battery assembly includes at least one first parallel battery string group, the first parallel battery string group including a first battery string and a second battery string arranged along the first direction. The first battery cell is located at the end of the first battery string, and the second battery cell is located at the end of the second battery string, with the first and second battery cells adjacent to each other; the busbar is disposed on the first battery cell and located on the side away from the second battery cell; the first solder strip is electrically connected to the third solder strip; the deflection section extends from the end of the body section away from the second battery cell and is connected to the busbar through the soldering section; the second solder strip extends outward from the side of the first battery cell away from the second battery cell and is connected to another battery cell.

12. The back contact battery assembly as claimed in claim 5, characterized in that, The back contact battery assembly includes at least one second parallel battery string group, the second parallel battery string group including a first battery string and a second battery string arranged along the first direction; The first battery cell is located at the end of the first battery string, the second battery cell is located at the end of the second battery string, and the first and second battery cells are adjacent to each other; the third welding strip has a bent section and an extended section; The busbar is disposed on the first battery cell and located on the side close to the second battery cell; the welding section is located on one side of the body section and connected to the busbar; the extension section is offset from the first welding strip in the first direction through the bending section and connected to the busbar on the other side of the body section.

13. The back contact battery assembly as described in any one of claims 10-12, characterized in that, It also includes an insulating strip, which is disposed between the busbar and the first battery cell, and the body segment and the second welding strip are insulated and isolated from the busbar by the insulating strip.

14. The back contact battery assembly as described in any one of claims 5, 10-12, characterized in that, The back contact battery assembly includes at least one third parallel battery string group, the third parallel battery string group including two battery strings arranged along the second direction; wherein, in the same second parallel battery string group, the same bus bar extends from the first battery cell in one battery string to the first battery cell in the other battery string to connect the two battery strings in the parallel battery string group in parallel.

15. The back contact battery assembly as claimed in claim 14, characterized in that, It also includes an insulating strip disposed between the busbar and the first battery cell, wherein the body segment and the second solder strip are insulated and isolated from the busbar by the insulating strip; the insulating strip extends along the busbar from the first battery cell in one battery string to the first battery cell in another battery string.

16. The back contact battery assembly as claimed in claim 13, characterized in that, The insulating strip has periodically arranged recesses, and the busbar is attached to the surface of the insulating strip to form a concave-convex structure. The recessed positions of the concave-convex structure are used to accommodate the welding segment.

17. A photovoltaic system, characterized in that, Includes the back contact battery assembly as described in any one of claims 1-16.

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