Back-contact battery strings and solar modules

Abstract

This application discloses a back-contact battery string group and a solar module, which relate to the technical field of photovoltaic power generation. The back-contact battery string group includes at least two battery strings, each including a plurality of battery cells arranged in a second direction and a ribbon. Two adjacent battery cells in the battery string are electrically connected via a plurality of ribbons arranged in a first direction. The distance between two adjacent ribbons in the battery string in the first direction is d1. In each battery string, the ribbon adjacent to the edge of the battery cell in the first direction is an end ribbon. The distance between the end ribbons of two adjacent battery strings in the first direction is d2, where 0.6≦d2 / d1<1. This reduces the probability of uneven pressure on the battery cells due to the flow of molten adhesive and impact of the molten adhesive on the ribbon. Furthermore, the risk of ribbon misalignment is reduced. The two adjacent end ribbons can distribute stress near the edges of the battery cells, reducing stress concentration and invisible cracking or fracture of the battery cells.

Description

[Technical Field]

[0001] This application relates to the field of photovoltaics, and more particularly to back-contacted cell strings and solar modules.

[0002] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to a Chinese patent application with application number 2023110430414, filed on August 17, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0003] A solar module is a modular structure in which multiple battery cells are formed through multiple processes, such as series welding, joining, laying, and lamination. During series welding, multiple battery cells are sequentially welded together using ribbons to form a battery string. However, due to the difference in height between the ribbons and the battery cells, stress is concentrated on the edges of the battery cells during the lamination process, making it easy for invisible cracks or fractures to occur in the battery cells. Summary of the Invention

[0004] The objective of the present application is to provide a back-contact battery string group and solar module that reduces the probability of uneven pressure on the battery cells due to the flow of molten adhesive and the impact of molten adhesive on the ribbons, further reducing the risk of ribbon misalignment, and allowing two adjacent end ribbons to distribute stress near the edges of the battery cells together, further reducing stress concentration and thereby reducing invisible cracks and fractures of the battery cells.

[0005] To achieve the above objectives, the present application provides the following technical solutions:

[0006] A back-contact battery string group including at least two battery strings arranged in a first direction, the battery strings comprising: a plurality of battery cells arranged in a second direction; a ribbon extending in the second direction and connected to the battery cell; two adjacent battery cells in the battery string are electrically connected via a plurality of ribbons arranged in a first direction, and the distance between two adjacent ribbons in the battery string in the first direction is d1; A back-contact battery string group, in which in each battery string, the ribbon adjacent to the edge of the battery cell in the first direction is an end ribbon, and the distance between the end ribbons of two adjacent battery strings in the first direction is d2, and 0.6≦d2 / d1<1.

[0007] In the present application, the ratio of the distance d2 between the end ribbons of two adjacent battery strings in the first direction to the distance d1 between two adjacent ribbons in the battery string in the first direction is set within a reasonable range, i.e., 0.6≦d2 / d1<1. This setting ensures that the distance d2 between the end ribbons of two adjacent battery strings is appropriately smaller than the distance d1 between the two adjacent ribbons in the battery string, preventing the distance d2 between the end ribbons of two adjacent battery strings from being too large. This also reduces the amount of adhesive flowing between the end ribbons of the two adjacent battery strings, reducing the likelihood of uneven pressure on the battery cells due to the flow of molten adhesive, reducing the impact of molten adhesive on the ribbons, and further mitigating the risk of ribbon misalignment. Furthermore, the two adjacent end ribbons can distribute stress near the edges of the battery cells, further reducing stress concentration and thereby reducing invisible cracks and fractures of the battery cells.

[0008] In the above embodiment, the distance d2 between the end ribbons of two adjacent battery strings can be prevented from being too small, thereby preventing the end ribbons of two adjacent battery strings from being too close to each other and causing a short circuit.

[0009] In one embodiment, the distance from the end ribbon to the edge of the battery cell in the first direction is d3, where 0.2≦d3 / d2≦0.4. This setting ensures a reasonable distance between the end ribbon and the edge of the battery cell, allowing the end ribbon to distribute stress near the edge of the battery cell during the lamination process and prevent stress concentration near the edge of the battery cell from causing invisible cracks or fractures in the battery cell. In addition, if the end ribbon of the battery cell is too close to the edge of the battery cell, the probability of invisible cracks at the edge of the battery cell increases, and current collection efficiency is also affected.

[0010] In one embodiment, d3 is 1 mm to 6 mm. This prevents the distance from the end ribbon to the edge of the battery cell from being too small, reducing the risk of shorting the end ribbons of adjacent battery strings, as well as reducing stress concentration near the edge of the battery cell and further reducing invisible cracks or fractures of the battery cell. And / or d1 is 8 mm to 11 mm. This setting allows the ribbon spacing to be set to a reasonable distance, allowing multiple ribbons to distribute pressure together during the lamination process, further reducing the risk of stress concentration in the battery cell.

[0011] In one embodiment, d2 is 3 mm to 12 mm. This ensures a reasonable distance between the end ribbon and the edge of the battery cell, and also ensures reasonable string spacing, which not only prevents the risk of two adjacent battery strings overlapping during the lamination process but also reduces stress concentration near the edge of the battery cell and reduces invisible cracks or fractures of the battery cell. And / or, the string spacing between two adjacent battery strings in the first direction is d4, and d4 is 0.5 mm to 2.5 mm. This ensures a reasonable string spacing between adjacent battery strings, which not only prevents the risk of two adjacent battery strings overlapping during the lamination process but also prevents the string spacing between two adjacent battery strings in the first direction from being too large, which would increase the overall size of the solar module.

[0012] In one embodiment, both sides of each battery cell in the second direction are a chamfered edge and a non-chamfered edge, respectively, the chamfered edge of one battery cell is adjacent to the chamfered edge of an adjacent battery cell and is electrically connected to it via a ribbon, and the non-chamfered edge of one battery cell is adjacent to the non-chamfered edge of another adjacent battery cell and is electrically connected to it via a ribbon. This makes it easier to align the chamfered edges of adjacent battery cells and the non-chamfered edges of adjacent battery cells during the battery cell arrangement process, avoids the difficulty of positioning the chamfered edges of adjacent battery cells, and optimizes the strength and aesthetics of the entire battery string.

[0013] In one implementation, in each battery string, two battery cells with adjacent non-chamfered sides are electrically connected via m ribbons, where m is an even number, and two battery cells with adjacent chamfered sides are electrically connected via n ribbons, where n is an odd number, and mn = 1. In this solution, among the multiple ribbons connected to the same battery cell, two end ribbons located on the side in the first direction may be located between two battery cells with adjacent non-chamfered sides, and when designing the distance d3 from the end ribbons to the edge of the battery cell, it is not necessary to consider that the end ribbons will avoid the chamfered area, and the distance d3 from the end ribbons to the edge of the battery cell will not be limited by the chamfered area, which is advantageous for rational design of the distance d3 from the end ribbons to the edge of the battery cell.

[0014] In one implementation, the edge ribbons are positioned between two adjacent battery cells with their non-chamfered edges, and the extension line of the edge ribbons passes through the chamfered areas of the battery cells, which allows for more ribbons to be provided, reducing stress concentrations near the edges of the battery cells and further reducing invisible cracks and fractures of the battery cells, while avoiding overlapping of the edge ribbons with the chamfered areas of the battery cells, and further preventing the edge ribbons from hanging over the chamfered areas, which would cause uneven stress, and preventing invisible cracks or fractures at the edges of the battery cells that may occur during the lamination process.

[0015] In one embodiment, the distance between two battery cells having adjacent chamfered edges in the second direction is greater than the distance between two battery cells having adjacent non-chamfered edges, so that the distance between the chamfered edges of the two adjacent battery cells is large, and when the chamfered edges of the two adjacent battery cells are deformed during lamination, they are less likely to come into contact with or overlap each other, thereby avoiding the occurrence of the integration phenomenon and reducing the risk of the battery cells integrating.

[0016] In one embodiment, the distance between two battery cells with adjacent chamfered sides in the second direction is 0.3 mm to 1.3 mm, and / or the distance between two battery cells with adjacent non-chamfered sides is 0.1 mm to 1.1 mm. This reduces the risk of the battery cells becoming integrated, prevents the overall length of the battery string from becoming too long, and improves the connection stability of adjacent battery cells.

[0017] In one implementation, a first polarity connection portion of a battery cell is electrically connected to a second polarity connection portion of an adjacent battery cell via a ribbon, and the second polarity connection portion of the battery cell is electrically connected to a first polarity connection portion of another adjacent battery cell via a ribbon, the ribbons connected to the first polarity connection portion of the battery cell and the ribbons connected to the second polarity connection portion of the battery cell are alternately arranged at intervals in a first direction, and the first polarity connection portion and the second polarity connection portion have opposite polarities, thereby improving current collection efficiency, making the current inside the battery cells more uniform, and reducing current loss inside the battery.

[0018] In one implementation, the first polarity connection and the second polarity connection are respectively P-type doped layer and N-type doped layer of the battery cell. For battery cells without a grid or main grid, the ribbons can be directly electrically connected to the P-type doped layer and N-type doped layer of the battery cell, realizing electrical connection between adjacent battery cells, and increasing the power of the module by reducing shielding and resistance losses, while reducing processing costs.

[0019] In one implementation, the first and second polarity connections are positive and negative grid lines of a battery cell, respectively.

[0020] A solar module including at least one back-contact battery string group, the back-contact battery string group being any of the back-contact battery string groups described above.

[0021] Compared with the related art, the beneficial effects of the solar module provided in the embodiments of the present application are the same as those of the back-contact cell string group, and therefore, a redundant description will be omitted here. [Brief explanation of the drawings]

[0022] The drawings described herein are intended to further the understanding of the present application and constitute a part of the present application, and the illustrative embodiments and the description thereof are intended to interpret the present application and are not intended to unduly limit the present application. [Figure 1] 1A and 1B are schematic diagrams of battery strings and ribbons provided in the examples of the present application. [Figure 2] 1 is a partial schematic diagram of adjacent battery strings in a first direction provided in an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0023] In order to make the technical problems to be solved, the technical solutions and the beneficial effects of the present application clearer and easier to understand, the present application will be described in more detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only for the purpose of interpreting the present application and are not intended to limit the present application.

[0024] When an element is referred to as being "fixed to" or "mounted on" another element, it should be understood that it may be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element.

[0025] Additionally, the terms "first" and "second" are for descriptive purposes only and should not be understood to indicate or imply relative importance or the number of technical features being indicated. Thus, a feature qualified as "first" or "second" may expressly or imply the inclusion of one or more of that feature. In this description, unless expressly and specifically limited, "plurality" means two or more than two. Unless expressly and specifically limited, "several" means one or more than one.

[0026] In the description of this application, orientations or positional relationships indicated by terms such as "upper," "lower," "front," "rear," "left," and "right" are orientations or positional relationships indicated based on the drawings, and their purpose is merely to facilitate and simplify the description of this application, and it should be understood that they should not be construed as limiting this application, as they do not expressly or imply that the indicated devices or elements necessarily have a specific orientation, or are configured and operated in a specific orientation.

[0027] It should be explained that in the present application, unless otherwise clearly defined or limited, the terms "attach," "couple," and "connect" should be understood in a broad sense, for example, to mean fixedly connected, detachably connected, integrally connected, mechanically connected, electrically connected, directly connected, or indirectly connected via an intermediate medium, or to allow the interiors of two elements to communicate or interact with each other. Those skilled in the art can understand the specific meanings of the above terms in the present invention according to specific circumstances.

[0028] As shown in Figures 1 and 2, the back-contact battery string group (hereinafter referred to as battery string group) provided in the present application includes at least two battery strings arranged in a first direction, i.e., the battery string group includes two or more battery strings, the multiple battery strings of the battery string group are arranged in the first direction, and the multiple battery strings of the battery string group are connected in series or in parallel.

[0029] Each battery string includes battery cells 1 and ribbons 2. In each battery string, the number of battery cells 1 is two or more, and the battery cells 1 of the battery string are arranged in the second direction. The ribbons 2 extend in the second direction, i.e., the longitudinal direction of the ribbons 2 extends in the second direction.

[0030] The ribbons 2 are connected to the battery cells 1, and two adjacent battery cells 1 in the battery string are electrically connected via the plurality of ribbons 2 arranged in a first direction, specifically, the plurality of ribbons 2 arranged in the first direction connect the two adjacent battery cells 1 in the battery string in series. The plurality of ribbons 2 between the two adjacent battery cells 1 are arranged in the first direction, and one end of the ribbon 2 is connected to the battery cell 1, and the other end of the ribbon 2 is connected to another battery cell 1.

[0031] The distance between two adjacent ribbons 2 in the first direction in each battery string is d1, that is, the distance between two adjacent ribbons 2 in the first direction among the multiple ribbons 2 connected to the same battery cell 1 is d1. Specifically, the distance between the edges of two adjacent ribbons 2 that are close to each other is d1.

[0032] In each battery string, the ribbon 2 adjacent to the edge of the battery cell 1 in the first direction is the end ribbon 2a, i.e., among the multiple ribbons 2 connected to the same battery cell 1, the ribbon 2 closest to the edge of the battery cell 1 in the first direction is the end ribbon 2a. The distance between the end ribbons 2a of two adjacent battery strings in the first direction is d2. Specifically, the distance between the adjacent edges of the end ribbons 2a of two adjacent battery strings in the first direction is d2, and 0.6≦d2 / d1<1.

[0033] During the lamination process, the adhesive film layer of the solar module melts under heat, and the molten adhesive becomes fluid. If the distance d2 between the end ribbons 2a of two adjacent battery strings in the first direction is large, the molten adhesive will easily flow between the end ribbons 2a of the two adjacent battery strings and into the gap between the two adjacent battery strings. This will result in uneven distribution of the molten adhesive after flow, which will cause uneven pressure on the battery cells 1 and make the battery cells 1 more susceptible to invisible cracks or fractures. In addition, the molten adhesive will easily impact the ribbons 2 while flowing, causing them to become misaligned.

[0034] Furthermore, the ribbons 2 themselves have a certain height, and typically have a circular cross section with a diameter of approximately 0.25 mm. When the ribbons 2 are connected to the battery cells 1, there is a certain height difference between the ribbons 2 and the surface of the battery cells 1, which causes stress to concentrate near the points where the battery cells 1 are connected to the ribbons 2 during the lamination process, making it easy for invisible cracks or fractures to occur in the battery cells 1. The applicant's research into the lamination process of solar modules has found that the greater the number of ribbons 2, the smaller the spacing between the ribbons 2, which makes the pressure that the battery cells 1 receive during the lamination process more uniform and makes it easier for stress to be dispersed; conversely, the fewer the number of ribbons 2, the greater the spacing between the ribbons 2, which causes stress to concentrate on the battery cells 1 during the lamination process, making it easy for invisible cracks or fractures to occur. As can be seen from the above, if the distance d2 between the end ribbons 2a of two adjacent battery strings in the first direction is too large, the molten adhesive will flow between the end ribbons 2a of the two adjacent battery strings, making it easy for the pressure received by the battery cell 1 to become uneven. Furthermore, the distance between the ribbons 2 near the edge of the battery cell 1 will be too great, making it difficult to distribute stress, and making it easy for invisible cracks or fractures to occur.

[0035] Based on the above, in the embodiment of the present application, the ratio of the distance d2 between the end ribbons 2a of two adjacent battery strings in the first direction to the distance d1 between two adjacent ribbons 2a in the battery string in the first direction is set within a reasonable range, i.e., 0.6≦d2 / d1<1. This setting ensures that the distance d2 between the end ribbons 2a of two adjacent battery strings is appropriately smaller than the distance d1 between two adjacent ribbons 2a in the battery string, preventing the distance d2 between the end ribbons 2a of two adjacent battery strings from being too large. This reduces adhesive flow between the end ribbons 2a of the two adjacent battery strings, reduces the probability of uneven pressure on the battery cell 1 due to the flow of molten adhesive, reduces the impact of the molten adhesive on the ribbons 2, and further reduces the risk of the ribbons 2 becoming misaligned. Furthermore, the two adjacent end ribbons 2a can distribute stress near the edges of the battery cell 1, further reducing stress concentration and thereby reducing invisible cracks and fractures of the battery cell 1. In addition, if the end ribbons of the battery cell are too close to the edge of the battery cell, the probability of invisible cracks occurring at the edge of the battery cell increases, and current collection efficiency is also affected.

[0036] In the above embodiment, the distance d2 between the end ribbons 2a of two adjacent battery strings can be prevented from being too small, thereby preventing the end ribbons 2a of two adjacent battery strings from being too close to each other and causing a short circuit.

[0037] 2 , the distance from the end ribbon 2a to the edge of the battery cell 1 in the first direction is d3. Specifically, the distance from the edge of the end ribbon 2a closest to the edge of the battery cell 1 in the first direction is d3, and 0.2≦d3 / d2≦0.4 is satisfied. This setting ensures a reasonable distance between the end ribbon 2a and the edge of the battery cell 1. During the lamination process, the end ribbon 2a can disperse stress near the edge of the battery cell 1, preventing stress concentration near the edge of the battery cell 1 from causing invisible cracks or fractures in the battery cell 1. Naturally, d3 / d2 may be slightly greater than 0.4 or slightly less than 0.2 and is not limited thereto.

[0038] In one specific embodiment, the distance d3 in the first direction from the end ribbon 2a to the edge of the battery cell 1 is 1 mm to 6 mm. If the distance d3 from the end ribbon 2a to the edge of the battery cell 1 is less than 1 mm, the distance between the end ribbons 2a of adjacent battery strings will be small, making short circuits more likely to occur. However, if the distance d3 from the end ribbon 2a to the edge of the battery cell 1 is greater than 6 mm, stress is likely to concentrate near the edge of the battery cell 1. Therefore, setting the distance d3 from the end ribbon 2a to the edge of the battery cell 1 within the range of 1 mm to 6 mm prevents the distance from the end ribbon 2a to the edge of the battery cell 1 from being too small, reducing the risk of short circuits between the end ribbons 2a of adjacent battery strings, reducing stress concentration near the edge of the battery cell 1, and further reducing invisible cracks and fractures of the battery cell 1. Illustratively, the distance d3 from the end ribbon 2a to the edge of the battery cell 1 may be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, or 6 mm, etc.

[0039] Furthermore, the distance d1 between two adjacent ribbons 2 in the first direction is 8 mm to 11 mm, i.e., among the multiple ribbons 2 connected to the same battery cell 1, the distance between two adjacent ribbons 2 in the first direction is 8 mm to 11 mm. By setting it in this manner, the interval between the ribbons 2 is set to a reasonable distance, and the multiple ribbons 2 distribute pressure together during the lamination process, further reducing the risk of stress concentration in the battery cell 1. For example, the distance d1 between two adjacent ribbons 2 in the first direction is 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 10.5 mm, or 11 mm.

[0040] Preferably, the distance d2 between the end ribbons 2a of two adjacent battery strings in the first direction is 3 mm to 12 mm. Since the distance d2 between the end ribbons 2a of two adjacent battery strings includes the distance d3 from the end ribbon 2a to the edge of the battery cell 1 and the string spacing d4 between two adjacent battery strings in the first direction, the distance d2 between the end ribbons 2a of two adjacent battery strings is within the range of 3 mm to 12 mm, which ensures a reasonable distance between the end ribbons 2a and the edge of the battery cell 1 and a reasonable string spacing, which not only prevents the risk of two adjacent battery strings overlapping during the lamination process but also reduces stress concentration near the edges of the battery cell 1 and further reduces invisible cracks and fractures of the battery cell 1. For example, the distance d2 between the end ribbons 2a of two adjacent battery strings in the first direction may be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, or 12 mm, etc., and is preferably 7 mm to 10 mm.

[0041] Furthermore, the string spacing between two adjacent battery strings in the first direction is d4, i.e., the distance between the edges of the adjacent battery cells 1 in adjacent battery strings in the first direction is d4, and d4 is within the range of 0.5 mm to 2.5 mm. If the string spacing d4 between two adjacent battery strings in the first direction is less than 0.5 mm, the string spacing between the adjacent battery strings is small and the adjacent battery strings are likely to overlap during the lamination process. However, if the string spacing d4 between two adjacent battery strings in the first direction is greater than 2.5 mm, the string spacing between the adjacent battery strings is too large, which increases the overall size of the solar module. Therefore, by setting the string spacing d4 between two adjacent battery strings in the first direction within the range of 0.5 mm to 2.5 mm, a reasonable string spacing between the adjacent battery strings is ensured, which not only prevents the risk of the adjacent battery strings overlapping during the lamination process but also prevents the overall size of the solar module from increasing due to the string spacing being too large. For example, the string spacing d4 between two adjacent battery strings in the first direction may be 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, etc. Of course, depending on the actual situation, the string spacing d4 between two adjacent battery strings may be slightly larger than 2.5 mm and is not limited here.

[0042] Battery cells 1 are typically formed by cutting a monocrystalline silicon rod into a square shape. Because monocrystalline silicon rods are generally cylindrical, battery cells 1 formed by cutting monocrystalline silicon rods into a square shape typically have rounded corners to maximize the light irradiation area and save silicon rod material. To achieve goals such as smoothing the edges and corners of the battery cell 1 and reducing stress at the edges and corners, the rounded corners typically need to be further processed so that the battery cell 1 has four smooth chamfers. Furthermore, to enable battery cells 1 to have different specifications and be applicable in different environments, the battery cell 1 may be further cut to divide it into smaller battery cells 1 of multiple specifications. After cutting, the battery cells 1 have a chamfered edge 1b on one side and a non-chamfered edge 1a on the other side.

[0043] In this embodiment, both sides of each battery cell 1 in the second direction are respectively a chamfered edge 1b and a non-chamfered edge 1a, i.e., both sides of the battery cell 1 facing in the second direction are respectively a chamfered edge 1b and a non-chamfered edge 1a rather than edges of the battery cell 1 parallel to the second direction. Specifically, both ends of one edge of the battery cell 1 in the first direction are chamfered, and that side of the battery cell 1 is a chamfered edge 1b. The other edge of the battery cell 1 is a straight edge in the first direction, and that side of the battery cell 1 is a non-chamfered edge 1a.

[0044] The chamfered edge 1b of one battery cell 1 is adjacent to the chamfered edge 1b of one adjacent battery cell 1 and is electrically connected to it via the ribbon 2, and the non-chamfered edge 1a of one battery cell 1 is adjacent to the non-chamfered edge 1a of another adjacent battery cell 1 and is electrically connected to it via the ribbon 2. Specifically, in each battery string, the chamfered edges 1b of adjacent battery cells 1 are adjacent to the chamfered edges 1b, and the non-chamfered edges 1a of adjacent battery cells 1 in the battery string are adjacent to the non-chamfered edges 1a. In a battery string, if the three battery cells 1 arranged sequentially in the second direction are a first battery cell, a second battery cell, and a third battery cell, the chamfered edge 1b of the first battery cell is adjacent to the chamfered edge 1b of the second battery cell, and the non-chamfered edge 1a of the second battery cell is adjacent to the non-chamfered edge 1a of the third battery cell. By setting it in this way, it becomes easier to align the chamfered edges 1b of adjacent battery cells 1 during the process of arranging the battery cells 1, and it also becomes easier to align the non-chamfered edges 1a of adjacent battery cells 1, avoiding difficulties in positioning the chamfered edges and non-chamfered edges 1a of adjacent battery cells 1 and optimizing the strength and aesthetics of the entire battery string. Naturally, in a battery string, the chamfered edge 1b of one battery cell 1 may be adjacent to the non-chamfered edge 1a of one adjacent battery cell 1, and the non-chamfered edge 1a of one battery cell 1 may be adjacent to the chamfered edge 1b of another adjacent battery cell 1, and this is not limited here.

[0045] Furthermore, in each battery string, two battery cells 1 adjacent to each other at their non-chamfered edges 1a are electrically connected via m ribbons 2, where m is an even number, and two battery cells 1 adjacent to each other at their non-chamfered edges 1b are electrically connected via n ribbons 2, where n is an odd number, and mn=1. For example, m may be 10 and n may be 9, i.e., the number of ribbons 2 connected to each battery cell 1 is 19. The battery cell 1 is electrically connected to its adjacent battery cell 1 at its non-chamfered edge 1a by 10 ribbons 2 and to its adjacent battery cell 1 at its chamfered edge 1b by 9 ribbons 2. Of course, m and n may be other numbers, such as 8 and 7, and those skilled in the art can freely set them according to actual circumstances. Two battery cells 1 adjacent to each other at their non-chamfered edges 1a are electrically connected via m+n ribbons 2, i.e., two battery cells 1 adjacent to each other at their non-chamfered edges 1a are electrically connected via an odd number of ribbons 2. In this embodiment, among the multiple ribbons 2 connected to the same battery cell 1, the two end ribbons 2a located on the side in the first direction may have their non-chamfered edges 1a located between two adjacent battery cells 1, and when setting the distance d3 from the end ribbons 2a to the edge of the battery cell 1, it is not necessary to consider that the end ribbons 2a will avoid the chamfered area, and the distance d3 from the end ribbons 2a to the edge of the battery cell 1 will not be limited by the chamfered area, which is advantageous for rational design of the distance d3 from the end ribbons 2a to the edge of the battery cell 1.

[0046] Preferably, the end ribbon 2a is located between two battery cells 1 whose non-chamfered edges 1a are adjacent, i.e., the end ribbon 2a is used to electrically connect the two battery cells 1 whose non-chamfered edges 1a are adjacent. This eliminates the need for the end ribbon 2a to avoid the chamfered area. In the second direction, the end ribbon 2a can be closer to the edge of the battery cell 1, and the extension line of the end ribbon 2a can pass through the chamfered area of ​​the battery cell 1. This allows more ribbons to be provided, reducing stress concentration near the edge of the battery cell 1 and further reducing invisible cracks and fractures of the battery cell 1. It also avoids overlapping of the end ribbon 2a with the chamfered area of ​​the battery cell 1, preventing the end ribbon 2a from hanging over the chamfered area and causing uneven stress, and preventing invisible cracks or fractures at the edge of the battery cell 1 that may occur during the lamination process. It should be noted that in this embodiment, the two battery cells 1 adjacent to each other with chamfered edges 1b are electrically connected only through the remaining ribbon 2 located between the two end ribbons 2a, and the remaining ribbon 2 located between the two end ribbons 2a is originally far away from the edge of the battery cell 1, making it easier for the ribbon 2 between the two battery cells 1 adjacent to each other with chamfered edges 1b to avoid the chamfered area so that it does not overlap with the chamfered area.

[0047] Of course, depending on the actual situation, two battery cells 1 having adjacent non-chamfered sides 1a may be electrically connected via an odd number of ribbons 2, and two battery cells 1 having adjacent chamfered sides 1b may be electrically connected via an even number of ribbons 2. In this way, the end ribbon 2a may be located between the two battery cells 1 having adjacent non-chamfered sides 1a, and the end ribbon 2a may pass through the chamfered area of ​​the battery cell 1, or a reduced number of end ribbons 2a may be provided to avoid the chamfered area of ​​the battery cell 1.

[0048] As can be seen from the above, in a battery string, if the number of ribbons 2 between two battery cells 1 adjacent to each other with chamfered edges 1b is odd and the number of ribbons 2 between two battery cells 1 adjacent to each other with non-chamfered edges 1a is even, it is advantageous for the polar connection parts to be arranged more closely and for electrons to be extracted more quickly, improving power generation efficiency and preventing the ribbons 2 from passing through the chamfered area, causing uneven stress, and preventing the battery cells 1 from breaking or cracking in an invisible manner, thereby improving the yield of solar modules.

[0049] Typically, in a battery string, multiple battery cells 1 are welded in an evenly spaced array structure, and when the spacing between two adjacent battery cells 1 is equal, it is more convenient to weld the entire battery string in series; however, warping occurs at the edges of the battery cells 1 after serial welding. When the battery cells 1 are flattened under force during lamination, the edges of two adjacent battery cells 1 are deformed under pressure and move closer to each other, which reduces the spacing between the two adjacent battery cells 1 and makes them more susceptible to integration, and the integration phenomenon is particularly severe for two battery cells 1 with adjacent chamfered edges 1b.

[0050] Based on the above, in this embodiment, the distance in the second direction between two battery cells 1 whose chamfered edges 1b are adjacent is greater than the distance between two battery cells 1 whose non-chamfered edges 1a are adjacent. The distance between two battery cells 1 whose chamfered edges 1b are adjacent is specifically the distance between the chamfered edges 1b of the two adjacent battery cells 1, and the distance between two battery cells 1 whose non-chamfered edges 1a are adjacent is specifically the distance between the non-chamfered edges 1a of the two adjacent battery cells 1. Because there is little ribbon 2 provided between the chamfered edges 1b of adjacent battery cells 1, the connection stability between the two chamfered edges 1b of adjacent battery cells 1 is low, and deformation and misalignment are likely to occur. When the distance between two battery cells 1 with adjacent chamfered edges 1b is greater than the distance between two battery cells 1 with adjacent non-chamfered edges 1a, the distance between the chamfered edges 1b of the two adjacent battery cells 1 is large, and when the chamfered edges 1b of the two adjacent battery cells 1 deform during lamination, they come close to each other and are less likely to come into contact or overlap, thereby avoiding the occurrence of the integration phenomenon and reducing the risk of the battery cells 1 becoming integrated.

[0051] Furthermore, the distance between two battery cells 1 whose chamfered edges 1b are adjacent in the second direction is 0.3 mm to 1.3 mm. If the distance between two battery cells 1 whose chamfered edges 1b are adjacent is less than 0.3 mm, the distance between the chamfered edges 1b of the two adjacent battery cells 1 will be too close, making it easier for them to become integrated. However, if the distance between two battery cells 1 whose chamfered edges 1b are adjacent is greater than 1.3 mm, the distance between the chamfered edges 1b of the two adjacent battery cells 1 will be too far, increasing the overall length of the battery string and reducing the connection stability of the adjacent battery cells 1. Therefore, by setting the distance between two battery cells 1 whose chamfered edges 1b are adjacent to 0.3 mm to 1.3 mm, the risk of the battery cells 1 becoming integrated is reduced, the overall length of the battery string is prevented from becoming too long, and the connection stability of the adjacent battery cells 1 is improved. For example, the distance between two battery cells 1 whose chamfered edges 1b are adjacent is 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, or 1.3 mm.

[0052] Furthermore, the spacing between two battery cells 1 whose non-chamfered sides 1a are adjacent in the second direction is 0.1 mm to 1.1 mm. If the spacing between two battery cells 1 whose non-chamfered sides 1a are adjacent is less than 0.1 mm, the distance between the non-chamfered sides 1a of the adjacent battery cells 1 will be short, making it easier for them to become integrated. However, if the spacing between two battery cells 1 whose non-chamfered sides 1a are adjacent is greater than 1.1 mm, the distance between the non-chamfered sides 1a of the adjacent battery cells 1 will be too great, increasing the overall length of the battery string and reducing the connection stability of the adjacent battery cells 1. Therefore, by setting the spacing between two battery cells 1 whose non-chamfered sides 1a are adjacent to 0.1 mm to 1.1 mm, the risk of the battery cells 1 becoming integrated is reduced, the overall length of the battery string is prevented from becoming too long, and the connection stability of the adjacent battery cells 1 is improved. Specifically, the distance between two battery cells 1 whose non-chamfered sides 1a are adjacent may be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, or the like.

[0053] Preferably, the distance in the second direction between two battery cells 1 whose chamfered sides 1b are adjacent is 0.3 mm to 1.3 mm, and the distance between two battery cells 1 whose non-chamfered sides 1a are adjacent is 0.1 mm to 1.1 mm. For example, if the distance between two battery cells 1 whose chamfered sides 1b are adjacent is 0.3 mm, the distance between two battery cells 1 whose non-chamfered sides 1a are adjacent is 0.1 mm to 0.2 mm, but if the distance between two battery cells 1 whose non-chamfered sides 1a are adjacent is 1.1 mm, the distance between two battery cells 1 whose chamfered sides 1b are adjacent is 1.2 mm to 1.3 mm. If the spacing between two battery cells 1 adjacent to each other with chamfered edges 1b is 0.6 mm, the spacing between two battery cells 1 adjacent to each other with non-chamfered edges 1a is 0.5 mm, but if the spacing between two battery cells 1 adjacent to each other with chamfered edges 1b is 0.9 mm, the spacing between two battery cells 1 adjacent to each other with non-chamfered edges 1a is 0.7 mm, etc. Those skilled in the art can set the spacing between two battery cells 1 adjacent to each other with chamfered edges 1b and the spacing between two battery cells 1 adjacent to each other with non-chamfered edges 1a according to actual circumstances.

[0054] In each of the above embodiments, the first polarity connection portion of a battery cell 1 is electrically connected to the second polarity connection portion of one adjacent battery cell 1 via the ribbon 2, and the second polarity connection portion of the battery cell 1 is electrically connected to the first polarity connection portion of another adjacent battery cell 1 via the ribbon 2, and the first polarity connection portion and the second polarity connection portion have opposite polarities. Specifically, in a battery string, if three battery cells 1 arranged sequentially in the second direction are a first battery cell, a second battery cell, and a third battery cell, the first polarity connection portion of the second battery cell is electrically connected to the second polarity connection portion of the first battery cell via the ribbon 2, and the second polarity connection portion of the second battery cell is electrically connected to the first polarity connection portion of the third battery cell via the ribbon 2, thereby realizing a series connection of the first battery cell, the second battery cell, and the third battery cell.

[0055] Furthermore, the ribbons 2 connected to the first polarity connection portions of the battery cells 1 and the ribbons 2 connected to the second polarity connection portions of the battery cells 1 are alternately arranged at intervals in the first direction, and the first polarity connection portions and second polarity connection portions of the battery cells 1 can be alternately arranged at intervals in the first direction; in other words, in the battery cell 1, one second polarity connection portion is provided between two adjacent first polarity connection portions in the first direction, and one first polarity connection portion is provided between two adjacent second polarity connection portions in the first direction. Because the ribbons 2 are connected to the first polarity connection portions or the second polarity connection portions, the ribbons 2 connected to the first polarity connection portions of the same battery cell 1 and the ribbons 2 connected to the second polarity connection portions of the battery cell 1 are also alternately arranged at intervals in the first direction, which can improve current collection efficiency and make the current inside the battery cells 1 more uniform, thereby reducing current loss inside the battery.

[0056] In a specific embodiment, the first polarity connection portion and the second polarity connection portion are respectively P-type doped layers and N-type doped layers of the battery cells 1. Specifically, the first polarity connection portion is a P-type doped layer and the second polarity connection portion is an N-type doped layer, or the first polarity connection portion is an N-type doped layer and the second polarity connection portion is a P-type doped layer. For battery cells 1 without a grid or main grid, the ribbons can be directly electrically connected to the P-type doped layers and N-type doped layers of the battery cells 1, realizing electrical connection between adjacent battery cells 1. This reduces shielding and resistance losses, thereby increasing the power of the module and reducing processing costs.

[0057] In another specific embodiment, the first polarity connection portion and the second polarity connection portion are respectively positive and negative grid lines of the battery cell 1. Specifically, the first polarity connection portion is a positive grid line and the second polarity connection portion is a negative grid line, or the first polarity connection portion is a negative grid line and the second polarity connection portion is a positive grid line. The battery cell 1 is provided with a plurality of positive and negative grid lines alternately arranged at intervals in the first direction, the positive and negative grid lines extend in the second direction, and the ribbon 2 is connected to the positive or negative grid lines to realize electrical connection between adjacent battery cells 1.

[0058] An embodiment of the present application further provides a solar module including at least one back-contact battery string group, the back-contact battery string group being the back-contact battery string group provided in any of the above embodiments. When the solar module includes multiple back-contact battery string groups, the multiple back-contact battery string groups may be arranged in the second direction, and the multiple back-contact battery string groups may be connected in parallel.

[0059] Compared with the related art, the beneficial effects of the solar module provided in the embodiments of the present application are the same as those of the back-contact cell string group described above, and therefore, a redundant description will be omitted here.

[0060] In the above description of the embodiments, the particular features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

[0061] The above are only specific embodiments of the present application, and the scope of protection of the present application is not limited thereto. Any changes or replacements that are easily conceivable to those skilled in the art within the technical scope described in the present application are included in the scope of protection of the present application. Therefore, the scope of protection of the present application shall be equivalent to the scope of protection of the claims. [Explanation of symbols]

[0062] 1 battery cell 1a Unchamfered edge 1b Chamfered edge 2. Ribbon 2a End ribbon

Claims

1. A back-contact battery string group including at least two battery strings arranged in a first direction, the battery strings comprising: a plurality of battery cells arranged in a second direction; a ribbon extending in the second direction and connected to the battery cell; two adjacent battery cells in the battery string are electrically connected via a plurality of ribbons arranged in a first direction, and the distance between two adjacent ribbons in the battery string in the first direction is d1; A back-contact battery string group, wherein in each battery string, a ribbon adjacent to an edge of a battery cell in the first direction is an end ribbon, and the distance between the end ribbons of two adjacent battery strings in the first direction is d2, and 0.6≦d2 / d1<1.

2. 2. The back-contact battery string group of claim 1, wherein the distance from the end ribbon to the edge of the battery cell in the first direction is d3, and 0.2≦d3 / d2≦0.

4.

3. 3. The back-contact battery string group of claim 2, wherein d3 is between 1 mm and 6 mm, and / or d1 is between 8 mm and 11 mm.

4. 2. The back-contact battery string group of claim 1, wherein d2 is 3 mm to 12 mm, and / or the string spacing between two adjacent battery strings in the first direction is d4, and d4 is 0.5 mm to 2.5 mm.

5. 2. The back-contact battery string group of claim 1, wherein both sides of any battery cell in the second direction are a chamfered side and a non-chamfered side, respectively, the chamfered side of the battery cell is adjacent to the chamfered side of one adjacent battery cell and is electrically connected to it via a ribbon, and the non-chamfered side of the battery cell is adjacent to the non-chamfered side of another adjacent battery cell and is electrically connected to it via a ribbon.

6. 6. The back-contact battery string group of claim 5, wherein in each battery string, two battery cells having adjacent non-chamfered sides are electrically connected via m ribbons, where m is an even number, and two battery cells having adjacent chamfered sides are electrically connected via n ribbons, where n is an odd number, and m-n=1.

7. 7. The back-contact battery string group of claim 6, wherein the non-chamfered edges of the end ribbons are located between two adjacent battery cells, and the extension lines of the end ribbons pass through the chamfered areas of the battery cells.

8. The back-contact battery string group of claim 5 , wherein the distance between two battery cells having adjacent chamfered sides in the second direction is greater than the distance between two battery cells having adjacent non-chamfered sides.

9. 9. The back-contact battery string group of claim 8, wherein in the second direction, the spacing between two battery cells having adjacent chamfered sides is 0.3 mm to 1.3 mm, and / or the spacing between two battery cells having adjacent non-chamfered sides is 0.1 mm to 1.1 mm.

10. 10. The back-contact battery string group of claim 1, wherein the first polarity connection portion of the battery cell is electrically connected to the second polarity connection portion of one adjacent battery cell via a ribbon, and the second polarity connection portion of the battery cell is electrically connected to the first polarity connection portion of another adjacent battery cell via a ribbon, the ribbons connected to the first polarity connection portion of the battery cell and the ribbons connected to the second polarity connection portion of the battery cell are alternately arranged at intervals in the first direction, and the first polarity connection portion and the second polarity connection portion have opposite polarities.

11. 11. The back-contact battery string group of claim 10, wherein the first polarity connection and the second polarity connection are P-type doped layers and N-type doped layers of a battery cell, respectively.

12. 11. The back-contact battery string group of claim 10, wherein the first polarity connection and the second polarity connection are positive and negative grid lines of a battery cell, respectively.

13. A solar module including at least one back-contact cell string, said back-contact cell string being the back-contact cell string of any one of claims 1 to 12.

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