Back contact battery assembly and photovoltaic system

Abstract

The invention is suitable for the technical field of solar cells, and provides a back contact cell module and a photovoltaic system. The back contact battery assembly comprises a first battery unit, the first battery unit comprises a first battery string and a second battery string which are arranged along a first direction, a back contact battery piece closest to a middle bus bar is a first end battery piece, and a back contact battery piece closest to a first end bus bar is a second end battery piece; and the distance between the second end part battery piece in the first battery string and the first end part bus bar is greater than the distance between the second end part battery piece in the second battery string and the first end part bus bar. On the basis, the end part battery pieces in the first battery string do not need to be accurately aligned and arranged, so that the process difficulty is reduced. And the second end part battery piece is closer to the first end part bus bar at the edge, so that a shadow shielding triggering mechanism can be triggered in time, and the condition of generating capacity loss caused by shadow shielding can be reduced.

Description

Technical Field

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

[0002] Currently, photovoltaic (PV) modules typically consist of several strings of cells arranged in an array, connected in series and parallel to form the module. In related technologies, each cell string needs to be precisely aligned, which is technically challenging, results in slow equipment operation, and low manufacturing efficiency. Furthermore, the shading mechanism is often delayed in its activation during periods of shadowing, leading to significant power generation losses.

[0003] Therefore, the delayed triggering of the shadow occlusion triggering mechanism has become an urgent problem to be solved. Summary of the Invention

[0004] This application provides a back-contact battery module and photovoltaic system, which aims to solve the problem of untimely triggering of the shading triggering mechanism.

[0005] The first aspect of this application provides a back contact battery assembly, the back contact battery assembly including a first battery unit, the first battery unit including a first battery string and a second battery string arranged along a first direction, the first battery string and the second battery string each including a plurality of back contact battery pieces arranged along a second direction and connected in series, the number of back contact battery pieces in the first battery string and the second battery string are the same, and the second direction intersects the first direction; In the second direction, the back contact battery assembly has a middle busbar and a first end busbar. In the first battery string and the second battery string, the back contact battery cell closest to the middle busbar is the first end battery cell, and the back contact battery cell closest to the first end busbar is the second end battery cell. Wherein, the first end battery cells in the first battery string and the second battery string are aligned in the first direction, and the distance between the second end battery cell in the first battery string and the first end busbar is greater than the distance between the second end battery cell in the second battery string and the first end busbar.

[0006] Optionally, the length difference between the second battery string and the first battery string in the second direction is less than 5 mm.

[0007] Optionally, the length difference between the second battery string and the first battery string in the second direction is less than 3 mm.

[0008] Optionally, the distance between the second end battery cell in the first battery string and the first end busbar is 10mm to 20mm, and the distance between the second end battery cell in the second battery string and the first end busbar is 5mm to 18mm.

[0009] Optionally, the first battery string and the second battery string are adjacent to each other, the first battery cell includes a plurality of first battery string groups, each first battery string group includes one first battery string and one second battery string, and the plurality of first battery string groups are arranged along the first direction.

[0010] Optionally, the lengths of the first battery strings in different first battery string groups may be the same or different in the second direction, and the lengths of the second battery strings in different first battery string groups may be the same or different in the second direction.

[0011] Optionally, in the first battery cell, there are multiple first battery strings and multiple second battery strings, and the length difference between the second battery string with the longest length in the second direction and the first battery string with the shortest length is less than 5 mm.

[0012] Optionally, the back contact battery assembly further includes a second battery unit, which is arranged along the second direction with the first battery unit. The second battery unit includes a third battery string and a fourth battery string arranged along the first direction. Both the third battery string and the fourth battery string include a plurality of back contact battery cells arranged along the second direction and connected in series. The number of back contact battery cells in the third battery string and the fourth battery string is the same. In the third battery string and the fourth battery string, the back contact battery cell closest to the second end busbar is the third end battery cell, and the back contact battery cell closest to the middle busbar is the fourth end battery cell. The third battery cell is adjacent to the first battery cell in the second direction. Wherein, the third end battery cells in the third battery string and the fourth battery string are aligned in the first direction, and the distance between the fourth end battery cell in the third battery string and the first edge is greater than the distance between the fourth end battery cell in the fourth battery string and the first edge.

[0013] Optionally, the length difference between the fourth battery string and the third battery string in the second direction is less than 5 mm.

[0014] Optionally, the length difference between the fourth battery string and the third battery string in the second direction is less than 3 mm.

[0015] Optionally, the spacing between the fourth end battery cell in the third battery string and the second end busbar is 10mm to 20mm, and the spacing between the fourth end battery cell in the fourth battery string and the second end busbar is 5mm to 18mm.

[0016] Optionally, the third battery string and the fourth battery string are adjacent to each other, and the second battery unit includes a plurality of second battery string groups, each of the second battery string groups including one third battery string and one fourth battery string, and the plurality of second battery string groups are arranged along the first direction.

[0017] Optionally, the lengths of the third battery strings in different second battery string groups may be the same or different in the second direction, and the lengths of the fourth battery strings in different second battery string groups may be the same or different in the second direction.

[0018] Optionally, in the second battery cell, there are multiple third battery strings and multiple fourth battery strings, and the length difference between the fourth battery string with the longest length in the second direction and the third battery string with the shortest length is less than 5 mm.

[0019] The second aspect of this application provides a photovoltaic system including the aforementioned first aspect and any optional back-contact battery module of the first aspect.

[0020] As can be seen from the above technical solutions, this application has the following effects: In the back-contact battery module and photovoltaic system of this application embodiment, since the distance between the second-end battery cell and the first-end busbar in the first battery string is greater than the distance between the second-end battery cell and the first-end busbar in the second battery string, it is no longer necessary to precisely align and arrange the back-contact battery cells in the first battery cell, reducing the process difficulty and increasing the working cycle time in the production process of the back-contact battery module, thereby improving manufacturing efficiency. Furthermore, when shading occurs, since the second-end battery cell in the second battery string is closer to the first-end busbar at the edge, the shadow will first shade the second-end battery cell in the second battery string, causing the hot spot temperature of the second-end battery cell in the second battery string to rise, triggering the shading triggering mechanism. Under the action of the shading triggering mechanism, the first and second battery strings simultaneously move away from the shadow, so that the second-end battery cell in the second battery string is not shaded by the shadow, thereby reducing the power generation loss caused by shading. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a back contact battery assembly according to an embodiment of this application; Figure 2This is a schematic diagram of the structure of a back contact battery assembly according to another embodiment of this application; Figure 3 This is a schematic diagram of the structure of a back contact battery assembly according to another embodiment of this application; Figure 4 This is a schematic diagram of the structure of a back contact battery assembly according to another embodiment of this application.

[0022] Explanation of key component symbols: First battery unit-1, first battery string group-10, first battery string-101, second battery string-102, first end battery cell-1001, second end battery cell-1002, intermediate busbar-2, first end busbar-3, second battery unit-4, second battery string group-40, third battery string-401, fourth battery string-402, third end battery cell-4001, fourth end battery cell-4002, second end busbar-5. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0024] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0027] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0029] Please see Figure 1 The back contact battery assembly of this application embodiment includes a first battery unit 1. The first battery unit 1 includes a first battery string 101 and a second battery string 102 arranged along a first direction. Both the first battery string 101 and the second battery string 102 include a plurality of back contact battery pieces arranged along a second direction and connected in series. The number of back contact battery pieces in the first battery string 101 and the second battery string 102 is the same. The second direction intersects the first direction. In the second direction, the back contact battery assembly has a middle busbar 2 and a first end busbar 3. In the first battery string 101 and the second battery string 102, the back contact battery piece closest to the middle busbar 2 is the first end battery piece 1001, and the back contact battery piece closest to the first end busbar 3 is the second end battery piece 1002. Wherein, the first end battery pieces 1001 in the first battery string 101 and the second battery string 102 are aligned in a first direction, and the spacing between the second end battery piece 1002 in the first battery string 101 and the first end busbar 3 is (e.g.) Figure 1 H1 shown is greater than the distance between the second end battery cell 1002 and the first end busbar 3 in the second battery string 102 (e.g., Figure 1 H2 as shown.

[0030] In this embodiment, since the distance between the second end battery cell 1002 in the first battery string 101 and the first end busbar 3 is greater than the distance between the second end battery cell 1002 in the second battery string 102 and the first end busbar 3, it is no longer necessary to precisely align and arrange the back contact battery cells in the first battery cell 1. This reduces the process difficulty, increases the working cycle in the production process of the back contact battery assembly, and thus improves manufacturing efficiency. Furthermore, when shadow occlusion occurs, since the second end battery cell 1002 in the second battery string 102 is closer to the first end busbar 3 at the edge, the shadow will first occlude the second end battery cell 1002 in the second battery string 102, causing the hot spot temperature of the second end battery cell 1002 in the second battery string 102 to rise, triggering the shadow occlusion triggering mechanism. Under the action of the shadow occlusion triggering mechanism, the first battery string 101 and the second battery string 102 move simultaneously away from the shadow, so that the second end battery cell 1002 in the second battery string 102 is not blocked by the shadow, thereby reducing the loss of power generation caused by shadow occlusion.

[0031] Specifically, the first battery string 101 and the second battery string 102 within the first battery unit 1 are connected in series along a first direction. A plurality of back-contact battery cells within the first battery string 101 are connected in series sequentially along a second direction. Similarly, a plurality of back-contact battery cells within the second battery string 102 are also connected in series sequentially along a second direction. The series connections between the back-contact battery cells in the first battery string 101 and the second battery string 102 are achieved through soldering. The number of back-contact battery cells in the first battery string 101 and the second battery string 102 is not limited, but the number of back-contact battery cells in the first battery string 101 and the second battery string 102 must be the same. For example, the number of back-contact battery cells in both the first battery string 101 and the second battery string 102 can be 5, 6, 7, or 8, or they can also be 12, 13, 14, or 15. The specific number can be set according to the actual power requirements and is not limited here.

[0032] It should be noted that the first direction and the second direction are not specific fixed directions, but rather two intersecting relative directions.

[0033] For example, if the first battery string 101 and the second battery string 102 are arranged from top to bottom, the first direction is the "vertical direction"; if the back contact battery pieces in the first battery string 101 and the second battery string 102 are arranged from left to right, the second direction is the "horizontal direction". At this time, the first direction and the second direction are perpendicular to each other.

[0034] For example, if the first battery string 101 and the second battery string 102 are arranged from left to right, the first direction is the "horizontal direction"; if the back contact battery pieces in the first battery string 101 and the second battery string 102 are arranged from top to bottom, the second direction is the "vertical direction". At this time, the first direction and the second direction are still perpendicular to each other.

[0035] Specifically, the intermediate busbar 2 and the first end busbar 3 are respectively disposed on the two ends of the first battery string 101 and the second battery string 102 in the second direction. The intermediate busbar 2 and the first end busbar 3 may be hidden on the back of the first battery string 101 and the second battery string 102, or they may not be hidden on the back of the first battery string 101 and the second battery string 102. The first end battery piece 1001 in the first battery string 101 and the second battery string 102 is connected to the intermediate busbar 2 by a solder strip, and the second end battery piece 1002 in the first battery string 101 and the second battery string 102 is connected to the first end busbar 3 by a solder strip.

[0036] For example, if the second direction is arranged from left to right, then the middle busbar 2 is located at the rightmost side of the first battery string 101 and the second battery string 102, and the rightmost back contact battery piece of the first battery string 101 and the second battery string 102 is the first end battery piece 1001; the first end busbar 3 is located at the leftmost side of the first battery string 101 and the second battery string 102, and the leftmost back contact battery piece of the first battery string 101 and the second battery string 102 is the second end battery piece 1002. Alternatively, the middle busbar 2 is located at the leftmost side of the first battery string 101 and the second battery string 102, and the leftmost back contact battery piece of the first battery string 101 and the second battery string 102 is the first end battery piece 1001; the first end busbar 3 is located at the rightmost side of the first battery string 101 and the second battery string 102, and the rightmost back contact battery piece of the first battery string 101 and the second battery string 102 is the second end battery piece 1002.

[0037] It is understood that in this embodiment, the first end busbar 3 and the intermediate busbar 2 are parallel to each other, and the first direction and the second direction are perpendicular to each other. The first direction can be a direction parallel to the first end busbar 3, or it can be understood as a direction parallel to the intermediate busbar 2, such as... Figure 1The direction indicated by arrow B in the diagram. The second direction can be perpendicular to the first end busbar 3, or it can be understood as perpendicular to the middle busbar 2, such as... Figure 1 The direction indicated by arrow A in the diagram.

[0038] Specifically, the first end battery cells 1001 in the first battery string 101 and the second battery string 102 are aligned in a first direction. This can be understood as follows: the spacing between the first end battery cells 1001 in the first battery string 101 and the intermediate busbar 2 is the same as the spacing between the first end battery cells 1001 in the second battery string 102 and the intermediate busbar 2. By aligning the first end battery cells 1001 in the first battery string 101 and the second battery string 102 in a first direction, the stability of current conduction can be ensured.

[0039] The distance between the second end battery piece 1002 in the first battery string 101 and the first end busbar 3 is greater than the distance between the second end battery piece 1002 in the second battery string 102 and the first end busbar 3. That is, the second end battery pieces 1002 in the first battery string 101 and the second battery string 102 that are furthest from the intermediate busbar 2 do not need to be forcibly aligned. The distance between the second end battery piece 1002 in the first battery string 101 and the first end busbar 3 can be referenced... Figure 1 In H1, the spacing between the second end battery cell 1002 and the first end busbar 3 in the second battery string 102 can be referenced. Figure 1 H2 in it.

[0040] Therefore, in the manufacturing process of back-contact battery modules, it is not necessary to precisely align the second-end battery cells 1002 with the first-end busbars 3 in different battery strings. This reduces the need for repeated adjustments to the positions of the first battery string 101 and the second battery string 102 by adding additional visual inspection equipment and moving equipment. This reduces the complexity of the process, increases the cycle time of manufacturing back-contact battery modules, and ultimately improves the production and manufacturing efficiency of back-contact battery modules.

[0041] Meanwhile, because the distance between the second end battery cell 1002 in the second battery string 102 and the first end busbar 3 is smaller than the distance between the second end battery cell 1002 in the first battery string 101 and the first end busbar 3, the shadow will first block the second end battery cell 1002 in the second battery string 102, and then move towards the second end battery cell 1002 in the first battery string 101, gradually blocking the second end battery cell 1002 in the first battery string 101. When the second end battery cell 1002 in the second battery string 102 is blocked by shadow, the power generation capacity will drop sharply, becoming a load that consumes the power of other battery cells, which will lead to a local temperature increase and form a hot spot effect. After the temperature detection device detects that the second end battery cell 1002 in the second battery string 102 has a hot spot effect, for example, if it detects that the temperature difference between the second end battery cell 1002 and other battery cells is greater than a preset temperature value or the current difference between the second end battery cell 1002 and other battery cells is greater than a preset current value, the shadow blocking triggering mechanism will be triggered immediately. When the shading trigger mechanism is activated, the central control system adjusts the bracket, causing the first battery string 101 and the second battery string 102 to move simultaneously away from the shadow. This allows the second end battery cell 1002 in the second battery string 102 to change from a shaded state to an unshaded state, thereby reducing power generation loss during the period from when the second end battery cell 1002 in the second battery string 102 is shaded until the shading is lifted.

[0042] If the spacing between the second end battery cell 1002 in the first battery string 101 and the first end busbar 3 is the same as the spacing between the second end battery cell 1002 in the second battery string 102 and the first end busbar 3, then when a shadow appears, the second end battery cell 1002 in both the first and second battery strings 101 will be simultaneously blocked by the shadow. This will cause both the second end battery cell 1002 in the first and second battery strings 101 to generate hot spots simultaneously, resulting in a failure to generate electricity for both the first and second end battery cell 1002 in the first and second battery strings 102, thus exacerbating the loss of power generation. Therefore, by setting the spacing between the second end battery cell 1002 in the first battery string 101 and the first end busbar 3 to be greater than the spacing between the second end battery cell 1002 in the second battery string 102 and the first end busbar 3, the shadow blocking triggering mechanism can be triggered in a timely manner, thereby reducing the loss of power generation.

[0043] It should be noted that the terms "first" and "second" in "first battery string 101" and "second battery string 102" are only used to distinguish different battery strings and do not represent specific battery strings. For example, if the first battery unit 1 includes battery string A and battery string B, battery string A can be designated as the first battery string 101 and battery string B as the second battery string 102; similarly, battery string A can be designated as the second battery string 102 and battery string B as the first battery string 101. Therefore, in another possible implementation, the distance between the second end battery piece 1002 and the first end busbar 3 in the first battery string 101 can be set to be smaller than the distance between the second end battery piece 1002 and the first end busbar 3 in the second battery string 102, achieving a similar effect to the aforementioned scheme.

[0044] In some embodiments, the length difference between the second battery string 102 and the first battery string 101 in the second direction is less than 5 mm.

[0045] Specifically, since the first end battery pieces 1001 in the first battery string 101 and the second battery string 102 are aligned in the first direction, the length difference between the second battery string 102 and the first battery string 101 in the second direction is the difference in spacing between the second end battery pieces 1002 in the first battery string 101 and the first end busbar 3.

[0046] It is understandable that if the length difference between the second battery string 102 and the first battery string 101 in the second direction is too large, it will affect the surface aesthetics of the back-contact battery assembly. Conversely, if the length difference between the second battery string 102 and the first battery string 101 in the second direction is too small, it may lead to a delayed triggering of the shading mechanism, thereby exacerbating power generation loss. In this embodiment, the length difference between the second battery string 102 and the first battery string 101 in the second direction can be 3.1mm, 3.2mm, 3.5mm, 3.8mm, or 4.2mm, 4.4mm, 4.6mm, 4.7mm, or any value less than 5mm and not 0mm; no specific limitation is made here. When the length difference between the second battery string 102 and the first battery string 101 in the second direction is within this range, it can maintain the surface aesthetics of the back-contact battery assembly to a certain extent while triggering the shading mechanism in a timely manner, reducing power generation loss. Furthermore, this numerical range is compatible with the dimensional deviations of most back-contact solar cells, avoiding warping or stress concentration problems that may occur during the assembly of back-contact solar modules, thereby improving the stability of the battery structure and the flexibility of the manufacturing process.

[0047] Furthermore, the length difference between the second battery string 102 and the first battery string 101 in the second direction is less than 3 mm.

[0048] Specifically, the length difference between the second battery string 102 and the first battery string 101 in the second direction can be set to 1.1mm, 1.2mm, 1.5mm, 1.8mm, or 2.2mm, 2.4mm, 2.6mm, 2.7mm, or any value less than 3mm and not 0mm. No specific limitation is made here. With the length difference between the second battery string 102 and the first battery string 101 within this range, the surface aesthetics of the back-contact battery assembly can be further improved without affecting the timely triggering of the shadow occlusion triggering mechanism.

[0049] In some embodiments, the distance between the second end battery piece 1002 in the first battery string 101 and the first end busbar 3 is 10mm to 20mm, and the distance between the second end battery piece 1002 in the second battery string 102 and the first end busbar 3 is 5mm to 18mm.

[0050] Specifically, if the spacing between the second-end battery cell 1002 in the first battery string 101 or the second battery string 102 and the first-end busbar 3 is too small, it may cause a short circuit in the connection circuit between the first-end busbar 3 and the second-end battery cell 1002 in the first battery string 101 or the second battery string 102, affecting the normal power generation of the second-end battery cell 1002 in the first battery string 101 or the second battery string 102. Simultaneously, it may also affect the heat dissipation of the first-end busbar 3.

[0051] If the distance between the second end battery cell 1002 in the first battery string 101 or the second battery string 102 and the first end busbar 3 is too large, it may increase the ineffective encapsulation area of ​​the back contact battery assembly and reduce the surface aesthetics of the back contact battery assembly.

[0052] Therefore, in such an embodiment, the spacing between the second end battery cell 1002 and the first end busbar 3 in the first battery string 101 can be set to 10mm, 11mm, 12mm, 15mm, 18mm, 19mm, or 20mm, or any value between 10mm and 20mm, without specific limitation here. The spacing between the second end battery cell 1002 and the first end busbar 3 in the second battery string 102 can be 5mm, 6mm, 7mm, 11mm, 16mm, 17mm, or 18mm, or any value between 5mm and 18mm, without specific limitation here. The spacing between the second end battery cell 1002 and the first end busbar 3 in the first battery string 101 and the second battery string 102 within this range can avoid short-circuit risks, maximize the effective power generation area, and improve aesthetics.

[0053] Please see Figure 2In some embodiments, the first battery string 101 and the second battery string 102 are adjacent to each other, and the first battery unit 1 includes a plurality of first battery string groups 10. Each first battery string group 10 includes a first battery string 101 and a second battery string 102, and the plurality of first battery string groups 10 are arranged along a first direction.

[0054] Specifically, in each first battery string group 10 within the first battery unit 1, the first battery string 101 and the second battery string 102 are connected to an intermediate busbar 2 and a first end busbar 3. The number of first battery string groups 10 within the first battery unit 1 can be one, two, three, or more, and is not limited here. By simultaneously arranging multiple first battery string groups 10 within the first battery unit 1, the overall power generation of the back-contact battery assembly can be improved.

[0055] Furthermore, the lengths of the first battery strings 101 in different first battery string groups 10 may be the same or different in the second direction, and the lengths of the second battery strings 102 in different first battery string groups 10 may be the same or different in the second direction.

[0056] Specifically, in each first battery string group 10, the first end battery pieces 1001 in the first battery string 101 and the second battery string 102 are aligned in the first direction. The distance between the second end battery piece 1002 in the first battery string 101 and the first end busbar 3 in each first battery string group 10 is greater than the distance between the second end battery piece 1002 and the first end busbar 3 in the second battery string 102. The length difference between the first battery strings 101 in different first battery string groups 10 and the length difference between the second battery strings 102 in different first battery string groups 10 are not limited in this embodiment; it is only necessary to limit the length difference between the first battery strings 101 and the second battery strings 102 in the same first battery string group 10 in the second direction. It is understood that the length of the first battery strings 101 and the second battery strings 102 in the second direction in different first battery string groups 10 are also not limited in this embodiment. For example, the length of the first battery string 101 in the second direction in the first battery string group 10A can be the same as or different from the length of the second battery string 102 in the second direction in the first battery string group 10B. Based on this, it can be applied to various sizes or types of back-contact solar cells, improving the process flexibility of back-contact solar cell assemblies.

[0057] In some embodiments, in the first battery cell 1, there are multiple first battery strings 101 and multiple second battery strings 102, and the length difference between the second battery string 102 with the longest length in the second direction and the first battery string 101 with the shortest length is less than 5 mm.

[0058] Specifically, the number of first battery strings 101 can be 1, 2, or 3, and the number of second battery strings 102 can also be 1, 2, or 3. The exact number of first battery strings 101 and second battery strings 102 is not limited here. It should be noted that the "first" in first battery string 101 and the "second" in second battery string 102 are determined based on a pre-defined naming rule, and do not specifically refer to any particular battery string. For example: the battery string with an odd number of positions in the first direction is designated as first battery string 101, and the battery string with an even number of positions in the first direction is designated as second battery string 102; or, the battery string with a length less than a preset length value in the second direction is designated as first battery string 101, and the battery string with a length greater than or equal to the preset length value in the second direction is designated as second battery string 102.

[0059] Therefore, it can be understood that the number of first battery strings 101 and second battery strings 102 can be the same or different, but it must be ensured that the number of each type of battery string 101 and battery string 102 is at least one. Simultaneously, as long as there is a length difference between the longest second battery string 102 and the shortest first battery string 101 in the second direction, the aforementioned effects of reducing process difficulty and power generation loss can be achieved. There is no need to restrict the length of all first battery strings 101 and second battery strings 102 in the second direction, thus improving process flexibility. The length difference between the longest second battery string 102 and the shortest first battery string 101 in the second direction can be 3.1mm, 3.2mm, 3.5mm, 3.8mm, or 4.2mm, 4.4mm, 4.6mm, 4.7mm, or any value less than 5mm and not 0mm; no specific limitation is made here. The length difference between the second battery string 102, which has the longest length in the second direction, and the first battery string 101, which has the shortest length, is within this range. This can maintain the aesthetic appearance of the back-contact battery assembly to a certain extent, while also triggering the shadow shading mechanism in a timely manner to reduce the loss of power generation.

[0060] Please see Figure 3 In some embodiments, the back contact battery assembly further includes a second battery unit 4, which is arranged along the second direction with the first battery unit 1. The second battery unit 4 includes a third battery string 401 and a fourth battery string 402 arranged along the first direction. Both the third battery string 401 and the fourth battery string 402 include a plurality of back contact battery cells arranged along the second direction and connected in series. The number of back contact battery cells in the third battery string 401 and the fourth battery string 402 is the same. In the third battery string 401 and the fourth battery string 402, the back contact battery cell closest to the second end busbar 5 is the third end battery cell 4001, and the back contact battery cell closest to the middle busbar 2 is the fourth end battery cell 4002. The third battery cell is adjacent to the first battery cell in the second direction. In this configuration, the third end battery pieces 4001 in the third battery string 401 and the fourth battery string 402 are aligned in the first direction, and the distance between the fourth end battery piece 4002 in the third battery string 401 and the first edge is greater than the distance between the fourth end battery piece 4002 in the fourth battery string 402 and the first edge.

[0061] Specifically, the third battery string 401 and the fourth battery string 402 within the second battery unit 4 are connected in parallel along the first direction. A plurality of back-contact battery cells within the third battery string 401 are connected in series along the second direction; similarly, a plurality of back-contact battery cells within the fourth battery string 402 are also connected in series along the second direction. The series connections between the back-contact battery cells in the third battery string 401 and the fourth battery string 402 are achieved through soldering. The number of back-contact battery cells in the third battery string 401 and the fourth battery string 402 is not limited, but the number of back-contact battery cells in the third battery string 401 and the fourth battery string 402 must be the same. For example, the number of back-contact battery cells in both the third battery string 401 and the fourth battery string 402 can be 5, 6, 7, or 8, or even 12, 13, 14, or 15. The specific number can be set according to the actual power requirements and is not limited here.

[0062] The intermediate busbar 2 and the second end busbar 5 are respectively located on the two ends of the third battery string 401 and the fourth battery string 402 in the second direction. The intermediate busbar 2 is used to realize the current convergence and conduction of the third battery string 401 and the fourth battery string 402, and also serves as one of the current acquisition points. The second end busbar 5 is used to collect the total current of the third battery string 401 and the fourth battery string 402. The third end battery cell 4001 in the third battery string 401 and the fourth battery string 402 is connected to the intermediate busbar 2 by soldering ribbon, and the fourth end battery cell 4002 in the third battery string 401 and the fourth battery string 402 is connected to the second end busbar 5 by soldering ribbon.

[0063] It should be noted that the intermediate busbar 2 is located between the first battery unit 1 and the second battery unit 4, and the intermediate busbar 2 is connected to the third end battery piece 4001 in the third battery string 401 and the fourth battery string 402, respectively.

[0064] Specifically, by setting a second battery unit 4, which functions similarly to the first battery unit 1, on the back contact battery assembly, the overall power generation of the back contact battery assembly can be improved. Simultaneously, when a shadow appears on one side of the second end busbar 5, the third end battery cell 4001 of the fourth battery string 402 preferentially generates a hot spot effect, triggering the shadow shading triggering mechanism. This causes the third battery string 401 and the fourth battery string 402 to move towards the direction of the middle busbar 2, ensuring that the fourth end battery cell 4002 of the third battery string 401 continues to generate power. This improves the trigger sensitivity of the shadow shading triggering mechanism of the back contact battery assembly, further expanding the shadow avoidance range of the back contact battery assembly.

[0065] In some embodiments, the length difference between the fourth battery string 402 and the third battery string 401 in the second direction is less than 5 mm.

[0066] Specifically, since the third end battery pieces 4001 in the third battery string 401 and the fourth battery string 402 are aligned in the first direction, the length difference between the fourth battery string 402 and the third battery string 401 in the second direction is the difference in spacing between the fourth end battery piece 4002 and the second end busbar 5 in the third battery string 401 and the fourth battery string 402.

[0067] It is understandable that if the length difference between the fourth battery string 402 and the third battery string 401 in the second direction is too large, it will affect the surface aesthetics of the back-contact battery module. Conversely, if the length difference between the fourth battery string 402 and the third battery string 401 in the second direction is too small, it may lead to a delayed triggering of the shading mechanism, thereby exacerbating power generation loss. In this embodiment, the length difference between the fourth battery string 402 and the third battery string 401 in the second direction can be 3.1mm, 3.2mm, 3.5mm, 3.8mm, or 4.2mm, 4.4mm, 4.6mm, 4.7mm, or any value less than 5mm and not 0mm; no specific limitation is made here. When the length difference between the fourth battery string 402 and the third battery string 401 in the second direction is within this range, it can maintain the surface aesthetics of the back-contact battery module to a certain extent while triggering the shading mechanism in a timely manner, reducing power generation loss. Furthermore, this numerical range is compatible with the dimensional deviations of most back-contact solar cells, avoiding warping or stress concentration problems that may occur during the assembly of back-contact solar modules, thereby improving the stability of the battery structure and the flexibility of the manufacturing process.

[0068] Furthermore, the length difference between the fourth battery string 402 and the third battery string 401 in the second direction is less than 3 mm.

[0069] Specifically, in order to further improve the surface aesthetics of the back contact battery assembly without affecting the timely triggering of the shadow occlusion triggering mechanism, the embodiment of this application can set the length difference between the fourth battery string 402 and the third battery string 401 in the second direction to be 1.1mm, 1.2mm, 1.5mm, 1.8mm, or 2.2mm, 2.4mm, 2.6mm, 2.7mm, or any value less than 3mm and not 0mm. No specific limitation is made here.

[0070] In some embodiments, the distance between the fourth end battery piece 4002 and the second end busbar 5 in the third battery string 401 is 10mm to 20mm, and the distance between the fourth end battery piece 4002 and the second end busbar 5 in the fourth battery string 402 is 5mm to 18mm.

[0071] Specifically, if the spacing between the fourth end battery cell 4002 in the third battery string 401 or the fourth battery string 402 and the second end busbar 5 is too small, it may cause a short circuit in the connection circuit between the second end busbar 5 and the fourth end battery cell 4002 in the third battery string 401 or the fourth battery string 402, affecting the normal power generation of the fourth end battery cell 4002 in the third battery string 401 or the fourth battery string 402. Simultaneously, it may also affect the heat dissipation of the second end busbar 5.

[0072] If the distance between the fourth end battery cell 4002 in the third battery string 401 or the second end busbar 5 is too large, it may increase the ineffective encapsulation area of ​​the back contact battery assembly and reduce the surface aesthetics of the back contact battery assembly.

[0073] Therefore, in such an embodiment, the spacing between the fourth end battery cell 4002 in the third battery string 401 and the second end busbar 5 can be set to 10mm, 11mm, 12mm, 15mm, 18mm, 19mm, or 20mm, or any value between 10mm and 20mm, without specific limitation here. The spacing between the fourth end battery cell 4002 in the fourth battery string 402 and the second end busbar 5 can be 5mm, 6mm, 7mm, 11mm, 16mm, 17mm, or 18mm, or any value between 5mm and 18mm, without specific limitation here. The spacing between the fourth end battery cell 4002 in the third battery string 401 and the second end busbar 5 within this range avoids short-circuit risks, maximizes the effective power generation area, and improves aesthetics.

[0074] Please see Figure 4In some embodiments, the third battery string 401 and the fourth battery string 402 are adjacent to each other, and the second battery unit 4 includes a plurality of second battery string groups 40. Each second battery string group 40 includes a third battery string 401 and a fourth battery string 402, and the plurality of second battery string groups 40 are arranged along a first direction.

[0075] Specifically, in each second battery string group 40 within the second battery unit 4, the third battery string 401 and the fourth battery string 402 are connected to an intermediate busbar 2 and a second end busbar 5. The number of second battery string groups 40 within the second battery unit 4 can be one, two, three, or more, and is not limited here. By simultaneously arranging multiple second battery string groups 40 within the second battery unit 4, the overall power generation of the back-contact battery assembly can be improved.

[0076] Furthermore, the lengths of the third battery string 401 in different second battery string groups 40 may be the same or different in the second direction, and the lengths of the fourth battery string 402 in different second battery string groups 40 may be the same or different in the second direction.

[0077] Specifically, in each second battery string group 40, the third end battery pieces 4001 in the third battery string 401 and the fourth battery string 402 are aligned in the first direction. The spacing between the fourth end battery piece 4002 in the third battery string 401 and the second end busbar 5 in each second battery string group 40 is greater than the spacing between the fourth end battery piece 4002 and the second end busbar 5 in the fourth battery string 402. The length difference between the third battery strings 401 in different second battery string groups 40 and the length difference between the fourth battery strings 402 in different second battery string groups 40 are not limited in this embodiment; it is only necessary to limit the length difference between the third battery strings 401 and the fourth battery strings 402 in the same second battery string group 40 in the second direction. It is understood that the lengths of the third battery strings 401 and the fourth battery strings 402 in the second direction in different second battery string groups 40 are also not limited in this embodiment. For example, the length of the third battery string 401 in the second battery string group 40A in the second direction can be the same as or different from the length of the fourth battery string 402 in the second battery string group 40B in the second direction. Based on this, it can be applied to various sizes or types of back-contact solar cells, improving the process flexibility of back-contact solar cell assemblies.

[0078] In some embodiments, in the second battery cell 4, there are multiple third battery strings 401 and multiple fourth battery strings 402, and the length difference between the fourth battery string 402 with the longest length in the second direction and the third battery string 401 with the shortest length is less than 5 mm.

[0079] Specifically, the number of third battery strings 401 can be 1, 2, or 3, and the number of fourth battery strings 402 can also be 1, 2, or 3. The exact number of third battery strings 401 and fourth battery strings 402 is not limited here. It should be noted that the "first" in third battery string 401 and the "second" in fourth battery string 402 are determined based on a pre-defined naming rule, and do not specifically refer to any particular battery string. For example: the battery string with an odd number of positions in the first direction is designated as the third battery string 401, and the battery string with an even number of positions in the first direction is designated as the fourth battery string 402; or, the battery string with a length less than a preset length value in the second direction is designated as the third battery string 401, and the battery string with a length greater than or equal to the preset length value in the second direction is designated as the fourth battery string 402.

[0080] Therefore, it can be understood that the number of third battery strings 401 and fourth battery strings 402 can be the same or different, but it must be ensured that the number of each type of third battery string 401 and fourth battery string 402 is at least one. Simultaneously, as long as there is a length difference between the longest fourth battery string 402 and the shortest third battery string 401 in the second direction, the aforementioned effects of reducing process difficulty and power generation loss can be achieved. There is no need to restrict the length of all third battery strings 401 and fourth battery strings 402 in the second direction, thus improving process flexibility. The length difference between the longest fourth battery string 402 and the shortest third battery string 401 in the second direction can be 3.1mm, 3.2mm, 3.5mm, 3.8mm, or 4.2mm, 4.4mm, 4.6mm, 4.7mm, or any value less than 5mm and not 0mm; no specific limitation is made here. The length difference between the fourth battery string 402, which has the longest length in the second direction, and the third battery string 401, which has the shortest length, is within this range. This can maintain the aesthetic appearance of the back-contact battery assembly to a certain extent, while also triggering the shadow shading mechanism in a timely manner to reduce the loss of power generation.

[0081] The photovoltaic system of this application includes the back contact battery module in any of the above optional embodiments.

[0082] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It 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.

[0083] In the description of this specification, the references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] Furthermore, the above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A back-contact battery assembly, characterized in that, The back contact battery assembly includes a first battery unit, the first battery unit includes a first battery string and a second battery string arranged along a first direction, the first battery string and the second battery string each include a plurality of back contact battery pieces arranged along the second direction and connected in series, the number of back contact battery pieces in the first battery string and the second battery string are the same, and the second direction intersects the first direction; In the second direction, the back contact battery assembly has a middle busbar and a first end busbar. In the first battery string and the second battery string, the back contact battery cell closest to the middle busbar is the first end battery cell, and the back contact battery cell closest to the first end busbar is the second end battery cell. Wherein, the first end battery cells in the first battery string and the second battery string are aligned in the first direction, and the distance between the second end battery cell in the first battery string and the first end busbar is greater than the distance between the second end battery cell in the second battery string and the first end busbar.

2. The back contact battery assembly according to claim 1, characterized in that, The length difference between the second battery string and the first battery string in the second direction is less than 5 mm.

3. The back contact battery assembly according to claim 2, characterized in that, The length difference between the second battery string and the first battery string in the second direction is less than 3 mm.

4. The back contact battery assembly according to claim 1, characterized in that, The distance between the second end battery cell in the first battery string and the first end busbar is 10mm to 20mm, and the distance between the second end battery cell in the second battery string and the first end busbar is 5mm to 18mm.

5. The back contact battery assembly according to claim 1, characterized in that, The first battery string and the second battery string are adjacent to each other. The first battery unit includes a plurality of first battery string groups. Each first battery string group includes one first battery string and one second battery string. The plurality of first battery string groups are arranged along the first direction.

6. The back contact battery cell according to claim 5, characterized in that, The lengths of the first battery strings in different first battery string groups may be the same or different in the second direction, and the lengths of the second battery strings in different first battery string groups may be the same or different in the second direction.

7. The back contact battery assembly according to claim 1, characterized in that, In the first battery cell, there are multiple first battery strings and multiple second battery strings. The length difference between the second battery string with the longest length in the second direction and the first battery string with the shortest length is less than 5 mm.

8. The back contact battery assembly according to claim 1, characterized in that, The back contact battery assembly further includes a second battery unit, which is arranged along the second direction with the first battery unit. The second battery unit includes a third battery string and a fourth battery string arranged along the first direction. The third battery string and the fourth battery string each include a plurality of back contact battery cells arranged along the second direction and connected in series. The number of back contact battery cells in the third battery string and the fourth battery string is the same. In the third battery string and the fourth battery string, the back contact battery cell closest to the second end busbar is the third end battery cell, and the back contact battery cell closest to the middle busbar is the fourth end battery cell. The third battery cell is adjacent to the first battery cell in the second direction. Wherein, the third end battery cells in the third battery string and the fourth battery string are aligned in the first direction, and the distance between the fourth end battery cell in the third battery string and the first edge is greater than the distance between the fourth end battery cell in the fourth battery string and the first edge.

9. The back contact battery assembly according to claim 8, characterized in that, The length difference between the fourth battery string and the third battery string in the second direction is less than 5 mm.

10. The back contact battery assembly according to claim 9, characterized in that, The length difference between the fourth battery string and the third battery string in the second direction is less than 3 mm.

11. The back contact battery assembly according to claim 8, characterized in that, The spacing between the fourth end battery cell in the third battery string and the second end busbar is 10mm to 20mm, and the spacing between the fourth end battery cell in the fourth battery string and the second end busbar is 5mm to 18mm.

12. The back contact battery assembly according to claim 8, characterized in that, The third battery string and the fourth battery string are adjacent to each other. The second battery unit includes a plurality of second battery string groups. Each second battery string group includes one third battery string and one fourth battery string. The plurality of second battery string groups are arranged along the first direction.

13. The back contact battery cell according to claim 12, characterized in that, The lengths of the third battery strings in different second battery string groups may be the same or different in the second direction, and the lengths of the fourth battery strings in different second battery string groups may be the same or different in the second direction.

14. The back contact battery assembly according to claim 8, characterized in that, In the second battery cell, there are multiple third battery strings and multiple fourth battery strings. The length difference between the fourth battery string with the longest length in the second direction and the third battery string with the shortest length is less than 5 mm.

15. A photovoltaic system, characterized in that, Includes the back contact battery assembly according to any one of claims 1 to 14.

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