Manufacturing method for photovoltaic module

Abstract

Disclosed is a manufacturing method for a back-contact cell assembly. Cell sheets are wound multiple times around the outer periphery of a cylindrical body along a first winding direction to obtain a first cell preform; a solder ribbon is wound around the outer periphery of the first cell preform, and an included angle between the winding direction of the solder ribbon and the first winding direction is an acute angle; and the solder ribbon is divided into a plurality of sub-solder ribbons along a target position.

Description

Methods for manufacturing photovoltaic modules

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to U.S. Patent Application No. 63 / 716,536, filed November 5, 2024, entitled “Method for Fabrication of Back Contact Battery Assembly,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of solar cell technology, and more specifically, to a method for preparing a back-contact solar cell module. Background Technology

[0004] Currently, back-contact solar cells refer to solar cells where the light-facing side of the cell has no electrodes, and both the positive and negative electrodes are located on the back side of the cell. This reduces the shading of the cells by the electrodes, increases the short-circuit current, and improves the energy conversion efficiency of the cells. However, in existing technologies, the electrodes and solder ribbons of back-contact solar cells are located on the back side of the cell. Due to thermal expansion and contraction, the solder ribbons may shift relative to the cell, making them prone to breakage or detachment. Summary of the Invention

[0005] According to one aspect of this disclosure, a method for fabricating a back-contact battery assembly is provided, comprising the following steps: providing a plurality of battery cells, each battery cell having a front side and a back side, the back side having a first doped layer and a second doped layer with opposite doping polarities, the first doped layer and the second doped layer extending along a first direction and alternately distributed along a second direction, wherein the first direction and the second direction intersect; wrapping the battery cells multiple times around the outer periphery of a column along a first circumferential direction to obtain a first battery preform having multiple battery cell groups, adjacent battery cell groups being spaced apart along the height direction of the column; wrapping a solder ribbon around the outer periphery of the first battery preform such that the solder ribbon contacts each battery cell, the angle between the winding direction of the solder ribbon and the first circumferential direction being an acute angle; dividing the solder ribbon into a plurality of sub-solder ribbons along a target position such that each sub-solder ribbon connects the first doped layer of a different battery cell and the second doped layer of an adjacent battery cell, the plurality of battery cells being connected by the sub-solder ribbons to form a battery string.

[0006] In some embodiments, any two adjacent cells in the same ring of cells have the same spacing, or at least some of any two adjacent cells in the same ring of cells are stacked.

[0007] In some embodiments, any two adjacent rings of solar cells have the same spacing.

[0008] In some embodiments, the step of obtaining the first battery preform includes: grouping a plurality of battery cells into groups, and sequentially adsorbing each group of battery cells onto the outer periphery of a column along a first circumferential direction to form a multi-ring battery cell group spaced apart along the height direction of the column.

[0009] In some embodiments, the column is a roller with multiple through holes distributed on its wall. The inside of the roller is connected to a vacuum pumping device. When the vacuum pumping device is in operation, the through holes have an adsorption force. In the step of setting the battery cells on the outer periphery of the column, the roller is driven by a driving device to rotate along a first circumferential direction, so that each battery cell is sequentially adsorbed onto the wall under the action of the adsorption force.

[0010] In some embodiments, in the step of winding the welding ribbon around the first battery preform, the roller rotates along the first circumferential direction under the drive of the drive device, so that the welding ribbon is sequentially wound onto the outer surface of each turn of the battery cell assembly under the drive of the roller.

[0011] In some embodiments, the angle α between the first circumferential direction and the winding direction of the solder strip satisfies the following relationship: 0<tanα≤D / L; where L is the total length between the outer end face of the first cell and the outer end face of the last cell in the same cell group along the first circumferential direction, and D is the width of any doped layer of the cell along the second direction.

[0012] In some embodiments, the minimum vertical distance H1 between the solder strips located on the outer periphery of adjacent cell arrays is equal; the center distance H2 between two adjacent doped layers is equal; H1 = H2.

[0013] In some embodiments, the step of dividing the solder ribbon into multiple sub-solder ribbons along a target location includes: defining the area between the first and last solar cell in the same solar cell group along a first circumferential direction as a first target area, and dividing the solder ribbon along positions corresponding to all the first target areas to obtain multiple second battery preforms, each second battery preform including all the solar cells in a solar cell group, the solar cells in each second battery preform being distributed along a first direction; defining the gap between adjacent solar cells in each solar cell group as a second target area, and dividing the solder ribbon into sub-solder ribbons along positions corresponding to the multiple second target areas, such that the sub-solder ribbons extend along a third direction and are alternately distributed along a second direction, each sub-solder ribbon connecting a first doped layer of a different solar cell and a second doped layer of an adjacent solar cell, wherein the angle between the first direction and the third direction is an acute angle.

[0014] In some embodiments, the preparation method further includes: adsorbing the outer periphery of the busbar structure onto the column so that the busbar structure is located between the first and last solar cells in the same ring of solar cells along the first circumferential direction.

[0015] In some embodiments, the widths of the first doped layer and the second doped layer are equal in the second direction.

[0016] In some embodiments, a grid line is provided on the back side, the grid line including a first grid line and a second grid line, the first grid line and the second grid line extending along a first direction and alternately distributed along a second direction, the first grid line being disposed on a first doped layer and the second grid line being disposed on a second doped layer; each sub-strip covers the first grid line of a different solar cell and the second grid line of an adjacent solar cell.

[0017] In some embodiments, the minimum vertical distance H1 between the solder strips located on the outer periphery of adjacent cell groups is equal; the minimum vertical distance H3 between any adjacent grid lines in the cell is equal; H1 = H3.

[0018] In some embodiments, in the same ring of solar cells, the first grid line, the second grid line, the first doped layer, and the second doped layer are all arranged in parallel.

[0019] In some embodiments, the sub-welding strip includes a first side and a second side, both of which extend along a third direction. On any cell, the first side includes a starting segment and a tail segment, and the distance between the grid line and the starting segment is greater than the distance between the grid line and the tail segment. The angle between the third direction and the first direction is an acute angle.

[0020] In some embodiments, the battery cells are rectangular in shape, and each battery cell includes a first battery cell and a second battery cell arranged sequentially along a first direction. Each battery cell includes a first edge and a second edge distributed along a second direction. The grid line of the first battery cell closest to the first edge is the first grid line, and the grid line of the second battery cell closest to the first edge is the second grid line.

[0021] In some embodiments, the distance between the starting segment and the first edge of the battery cell is less than the distance between the tail segment and the first edge of the battery cell.

[0022] In some embodiments, the first edge of the solar cell is arranged parallel to the doped layer or grid lines.

[0023] In some embodiments, the solder ribbon includes a first solder ribbon segment and a second solder ribbon segment located on the outer periphery of each coil of the cell array, the first solder ribbon segment and the second solder ribbon segment being alternately connected along the winding direction; the first solder ribbon segment covers and connects the first doped layer or the first grid line of the first cell and the second doped layer or the second grid line of the second cell; the second solder ribbon segment covers and connects the second doped layer or the second grid line of the first cell and the first doped layer or the first grid line of another second cell.

[0024] In some embodiments, the solder strip is elongated and its width is less than the spacing between the first and second grid lines of any given cell. Attached Figure Description

[0025] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure. In the drawings:

[0026] Figure 1 is a schematic flowchart of a method for preparing a back contact battery assembly according to an embodiment of this disclosure;

[0027] Figure 2 is a top view schematic diagram of a battery cell provided in a method for preparing a back contact battery assembly according to an embodiment of the present disclosure;

[0028] Figure 3 is a top view schematic diagram of another type of battery cell provided in a method for preparing a back contact battery assembly according to an embodiment of this disclosure;

[0029] Figure 4 is a schematic diagram of the structure of a back contact battery assembly fabrication method provided in this embodiment, in which the battery cell is disposed on one side of the outer periphery of the column.

[0030] Figure 5 is a schematic diagram of the structure on the other side after the battery cell is disposed on the outer periphery of the column in a method for preparing a back contact battery assembly according to an embodiment of the present disclosure.

[0031] Figure 6 is a schematic diagram of one side of the structure after the welding strip is installed on the outer periphery of the column shown in Figure 4;

[0032] Figure 7 is a schematic diagram of the structure on the other side after the welding strip is installed on the outer periphery of the column shown in Figure 5;

[0033] Figure 8 is a schematic diagram of the structure on the other side after the busbar is installed on the outer periphery of the column.

[0034] Figure 9 is a partial planar structural schematic diagram of a back contact battery assembly obtained by a method for preparing a back contact battery assembly according to an embodiment of this disclosure.

[0035] Figure 10 is a schematic diagram of another part of the planar structure of a back contact battery assembly obtained by a method for preparing a back contact battery assembly according to an embodiment of the present disclosure.

[0036] Figure 11 is a schematic diagram of another part of the planar structure of a back contact battery assembly obtained by a method for preparing a back contact battery assembly according to an embodiment of the present disclosure.

[0037] Figure 12 is a schematic diagram of a portion of the planar structure of a back contact battery assembly obtained by a method for preparing a back contact battery assembly according to an embodiment of the present disclosure.

[0038] Figure 13 is a schematic diagram of the module structure of a back contact battery assembly obtained by a method for preparing a back contact battery assembly according to an embodiment of the present disclosure.

[0039] Figure 14 is a schematic diagram of the structure of a photovoltaic system provided in an embodiment of this disclosure.

[0040] Explanation of reference numerals in the attached drawings: 100, back contact battery module; 10, battery cell; 11, front side; 12, back side; 121, first grid line; 122, second grid line; 123, first doped layer; 124, second doped layer; 13, first edge; 14, second edge; 101, first battery cell; 102, second battery cell; 110, column; 120, battery cell assembly; 20, sub-weld ribbon; 201, ribbon; 21, first ribbon; 210, first ribbon segment; 22, second ribbon; 220, second ribbon segment; 23, first side; 231, starting segment; 232, ending segment; 24, second side; 30, busbar structure; 200, battery string; 300, photovoltaic system. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this disclosure 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 disclosure, and should not be construed as limiting this disclosure. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this disclosure and are not intended to limit this disclosure.

[0042] In the description of this disclosure, 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 disclosure and simplifying the description, and are not intended to 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 disclosure.

[0043] 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 disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" 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 disclosure according to the specific circumstances.

[0045] In this disclosure, 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.

[0046] The following disclosure provides numerous different embodiments or examples for implementing various structures of this disclosure. 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 disclosure. 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 disclosure, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0047] In related technologies, a solar cell is a semiconductor device that directly converts the energy of sunlight into electrical energy. Solar cells utilize the photovoltaic effect, absorbing photons to excite electrons and then using a built-in electric field to guide these electrons and generate current. A back-contact solar cell refers to a solar cell where the light-facing side of the cell has no electrodes, and both the positive and negative electrodes are located on the back side of the cell. This reduces electrode shading of the cell, increases the short-circuit current, and improves the energy conversion efficiency. However, in existing technologies, the electrodes and solder ribbons of back-contact solar cells are located on the back side of the cell. Due to thermal expansion and contraction, the solder ribbons may shift relative to the cell, causing them to easily break or detach. In this embodiment, the solder ribbons can be angled at an acute angle to the doped layer to increase the contact area between the solder ribbons and the cell, thereby increasing the electrical contact area between the solder ribbons and the doped layer and improving the conductivity from the doped layer to the solder ribbons. Simultaneously, the angled arrangement of the solder ribbons can alleviate stress concentration, ensuring a stable connection between the solder ribbons and the cell.

[0048] According to embodiments of this disclosure, a method for fabricating a back-contact battery assembly is provided, comprising the following steps: providing a plurality of battery cells, each battery cell having a front side and a back side, the back side having a first doped layer and a second doped layer with opposite doping polarities, the first doped layer and the second doped layer extending along a first direction and alternately distributed along a second direction, wherein the first direction and the second direction intersect; wrapping the battery cells multiple times around the outer periphery of a column along a first circumferential direction to obtain a first battery preform with multiple battery cell groups, adjacent battery cell groups being spaced apart along the height direction of the column; wrapping a solder ribbon around the outer periphery of the first battery preform so that the solder ribbon contacts each battery cell, the angle between the winding direction of the solder ribbon and the first circumferential direction being an acute angle; dividing the solder ribbon into a plurality of sub-solder ribbons along a target position so that each sub-solder ribbon connects the first doped layer of a different battery cell and the second doped layer of an adjacent battery cell, the plurality of battery cells being connected by the sub-solder ribbons to form a battery string, i.e., each sub-solder ribbon connects only two battery cells, and the dividing points are intersecting.

[0049] Figure 1 is a flowchart according to an embodiment of the present disclosure. As shown in Figure 1, the preparation method includes the following steps:

[0050] S1 provides multiple solar cells, each solar cell having a front side and a back side, the back side having a first doped layer and a second doped layer with opposite doping polarities, the first doped layer and the second doped layer extending along a first direction and alternately distributed along a second direction, wherein the first direction and the second direction intersect.

[0051] S2, the battery cells are wrapped around the outer periphery of the column multiple times along the first circumferential direction to obtain a first battery preform with multiple battery cell groups, and adjacent battery cell groups are distributed at intervals along the height direction of the column.

[0052] S3, the welding ribbon is wrapped around the outer periphery of the first battery preform so that the welding ribbon contacts each battery cell, and the angle between the winding direction of the welding ribbon and the first circumferential direction is an acute angle;

[0053] S4, the solder ribbon is divided into multiple sub-solder ribbons along the target position so that each sub-solder ribbon connects the first doped layer of different solar cells and the second doped layer of adjacent solar cells, and multiple solar cells are connected through the sub-solder ribbons to form a solar cell string.

[0054] The above method uses only one solder strip to connect multiple solar cells in series. The process is simple and easy to implement. Furthermore, by setting the solder strip at an acute angle to the doped layer, the contact area between the solder strip and the solar cell can be increased, thereby increasing the electrical contact area between the solder strip and the doped layer and improving the conductivity from the doped layer to the solder strip. Simultaneously, the inclined setting of the solder strip can alleviate stress concentration issues, ensuring a stable connection between the solder strip and the solar cell.

[0055] Exemplary embodiments of the method for fabricating the back contact battery assembly according to the present disclosure will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that this disclosure will be thorough and complete, and that the concept of these exemplary embodiments will be fully conveyed to those skilled in the art.

[0056] First, step S1 is performed: As shown in Figure 2, a plurality of solar cells 10 are provided. Each solar cell 10 has a front side and a back side. The back side has a first doped layer 123 and a second doped layer 124 with opposite doping polarities. The first doped layer 123 and the second doped layer 124 extend along a first direction and are alternately distributed along a second direction, wherein the first direction and the second direction intersect. It should be noted that, although not shown in Figure 2, there may be a gap between adjacent doped layers.

[0057] Specifically, the front side 11 of the solar cell 10 is used to receive light, and the back side 12 of the solar cell 10 includes a plurality of alternating first doped layers 123 and second doped layers 124, both of which extend along a first direction to form a photocurrent.

[0058] It should be noted that this disclosure does not limit the doping type of the first doped layer 123 and the second doped layer 124. For example, the first doped layer 123 and the second doped layer 124 can be P-type doped layers and N-type doped layers, respectively; alternatively, the first doped layer 123 can be an N-type doped layer and the second doped layer 124 can be a P-type doped layer, as long as their polarities are opposite to meet different requirements. In some embodiments, the first doped layer 123 can be a P-type polycrystalline silicon layer, a P-type amorphous silicon layer, or a P-type microcrystalline silicon layer, and there is no specific limitation here. Similarly, the second doped layer 124 can be an N-type polycrystalline silicon layer, an N-type amorphous silicon layer, or an N-type microcrystalline silicon layer, and there is no specific limitation here. When the first doped layer 123 is a P-type doped layer and the second doped layer 124 is an N-type doped layer, P-type gate lines can also be provided on the first doped layer 123, and N-type gate lines can also be provided on the second doped layer 124, and there is no specific limitation here.

[0059] In the battery cells provided in this disclosure, P-type doping refers to doping with group III elements, including boron, aluminum, gallium, indium, thallium, etc., and N-type doping refers to doping with group V elements, including nitrogen, phosphorus, arsenic, antimony, bismuth, etc., and the specific doping is not limited here.

[0060] In some embodiments, the first doped layer 123 and the second doped layer 124 can also be composite doped, for example, N-type doping also includes a small amount of P-type doping elements. Specifically, the N-type doping element content of the second doped layer 124 is higher than the P-type doping element content by 20% to ensure that its polarity is opposite to that of the first doped layer 123.

[0061] In the battery cell provided in this embodiment, as shown in FIG2, the first direction and the second direction can be perpendicular. In this case, the battery cell 10 can be rectangular, and the first direction and the second direction are also the edge directions of the battery cell 10, so as to maximize the utilization of the area of ​​the battery cell 10.

[0062] In this embodiment, the type of solar cell 10 is not limited to meet different needs. For example, the solar cell 10 can be a type without grid lines, where current conduction is achieved through direct connection between the solder ribbon and the doped layer. Furthermore, in this embodiment, the width of the doped layer of the solar cell 10 is uniform in the second direction.

[0063] Referring to Figure 3, in some optional embodiments, the back surface 12 of the solar cell 10 is provided with a first grid line 121 and a second grid line 122. The first grid line 121 and the second grid line 122 extend along a first direction and are alternately distributed along a second direction. The first grid line 121 is disposed on a first doped layer 123, and the second grid line 122 is disposed on a second doped layer 124. In this way, the first doped layer 123 and the second doped layer 124 can conduct current through the first grid line 121 and the second grid line 122. The sub-weld strips obtained after subsequent segmentation cover the first grid line 121 of the solar cell 10 and the second grid line 122 of the adjacent solar cell 10, so that current can be combined and conducted through the sub-weld strips.

[0064] Specifically, as shown in Figure 3, the first grid line 121 and the second grid line 122 are alternately distributed on the back surface 12 of the solar cell 10 to ensure uniformity of current collection and conduction and reduce current loss. The first grid line 121 is independently disposed on the first doped layer 123, and the second grid line 122 is independently disposed on the second doped layer 124, avoiding interference between grid lines on the same doped layer and improving the efficiency of current conduction. Subsequently segmented sub-weld ribbons cover the first grid line 121 and the second grid line 122 of the adjacent solar cell 10, realizing current convergence between multiple solar cells 10 through the sub-weld ribbons, ensuring efficient current conduction.

[0065] Furthermore, the spacing between the first grid line 121 and the second grid line 122 can be flexibly adjusted according to actual needs. The first grid line 121 and the second grid line 122 can be set with equal spacing, which can ensure uniform current distribution and improve the overall efficiency of the back contact battery module 100; non-equal spacing can optimize the current conduction path for specific application scenarios and reduce problems such as local overheating or excessive resistance. A combination of partially equal spacing and partially non-equal spacing can combine the advantages of both and be flexibly adjusted according to specific needs to optimize the performance of the back contact battery module 100.

[0066] Referring to Figure 3, in some optional embodiments, the battery cells 10 are all rectangular in shape. Each battery cell 10 includes a first battery cell 101 and a second battery cell 102 arranged sequentially along a first direction. Each battery cell 10 includes a first edge 13 and a second edge 14 distributed along a second direction. The grid line closest to the first edge 13 on the first battery cell 101 is the first grid line 121, and the grid line closest to the first edge 13 on the second battery cell 102 is the second grid line 122. This ensures that each grid line is covered by the subsequently distributed sub-weld ribbons. Simultaneously, the grid lines on the same straight line between two adjacent battery cells 10 have opposite polarities, allowing the sub-weld ribbons to connect the first battery cell 101 and the second battery cell 102 in series.

[0067] Specifically, the solar cell 10 is rectangular, which facilitates mass production and arrangement, and improves space utilization. The solar cell 10 has a first edge 13 and a second edge 14 distributed along a second direction, which helps in the rational arrangement of the grid lines and current collection.

[0068] In this embodiment, the shape of the battery cell 10 is not limited to meet different requirements. For example, the battery cell 10 can be a rectangular or square whole battery cell 10. Then, the square whole battery cell 10 is designed to correspond to a single rectangular battery cell 10 or a single cut battery cell 10 divided into slices (two slices, three slices, etc.). The main feature of such a battery cell 10 is that there are no grid lines and electrode structures on the front side 11, and the positive and negative grid lines are distributed alternately on the back side 12 of the battery cell 10. In addition, in this embodiment, the number, size range, and spacing between adjacent grid lines of the first grid line 121 and the second grid line 122 are not limited, as long as the grid lines can be covered by the subsequently divided sub-weld strips 20 to meet different requirements.

[0069] For example, the first gate line 121 can be the positive electrode and the second gate line 122 can be the negative electrode. Of course, in other embodiments, the opposite can be true, that is, the first gate line 121 can be the negative electrode and the second gate line 122 can be the positive electrode; no specific limitation is made here. The alternating distribution of the first gate line 121 and the second gate line 122 and their precise connection with the solder ribbon enable more efficient current collection and transmission, reducing fine gate electrical losses.

[0070] Referring to Figures 2 and 3, in some alternative embodiments, the first edge 13 of the solar cell 10 is arranged parallel to the doped layer or grid lines. Thus, the first edge 13 and the second edge 14 of the solar cell 10 can extend along a first direction, the same as the extension direction of the doped layer or grid lines, thereby allowing the solar cell 10 to be rectangular, facilitating mass production and arrangement, and improving space utilization.

[0071] It is understandable that "first" and "second" in the context of the first battery cell 101 and the second battery cell 102 are relative concepts, referring to two different back-contact batteries. For example, in the example in Figure 3, the back-contact battery on the left is labeled as the first battery cell 101, and the back-contact battery on the right is labeled as the second battery cell 102.

[0072] After the step of providing multiple battery cells, step S2 is performed: as shown in Figures 4 and 5, the battery cell 10 is wrapped around the outer periphery of the column 110 multiple times along the first circumferential direction A to obtain a first battery preform with multiple battery cell groups 120, and adjacent battery cell groups 120 are spaced apart along the height direction of the column.

[0073] It should be noted that the first surrounding direction A can be the circumferential direction of the column 110, but it is not limited to the above direction. For example, the angle between the first surrounding direction A and the circumferential direction of the column 110 can be an acute angle. This disclosure does not make specific limitations.

[0074] In some alternative embodiments, any two adjacent cells 10 in the same ring of cell pack 120 have the same spacing. By ensuring that the cells 10 in each ring of cell pack 120 have the same spacing, it is beneficial for the battery strings obtained after cutting the solder ribbon to have the same length. This facilitates the formation of back-contact battery assemblies using battery strings connected by the aforementioned sub-solder ribbons after the solder ribbon is divided into sub-solder ribbons.

[0075] In some alternative embodiments, any two adjacent coils of solar cells 120 have the same spacing. By arranging adjacent coils of solar cells 120 at equal intervals, it is beneficial for the solder ribbon to be wound evenly on the surface of the solar cell 10, so that after the solder ribbon is divided into sub-solder ribbons, the solar cells in each coil of solar cells can be distributed with the same number of sub-solder ribbons.

[0076] In some alternative embodiments, the step of obtaining the first battery preform includes: grouping a plurality of battery cells 10 into groups, and sequentially adsorbing each group of battery cells onto the outer periphery of the column 110 along a first circumferential direction A to form a multi-ring battery cell group 120 spaced apart along the height direction of the column 110.

[0077] In the above optional embodiments, the column 110 can be a roller with multiple through holes distributed on the cylinder wall. The inside of the roller is connected to a vacuum pumping device. When the vacuum pumping device is in operation, the through holes have an adsorption force. Thus, by driving the roller to rotate along the first circumferential direction, each battery cell 10 is sequentially adsorbed onto the cylinder wall under the action of the adsorption force.

[0078] In the above optional embodiments, after the battery cells 10 are arranged on the outer periphery of the roller to form a multi-turn battery cell group 120, the roller can be rotated along the first circumferential direction A under the drive of the drive device, so that the welding strip is sequentially wound onto the outer surface of each turn of the battery cell group 120 under the drive of the roller.

[0079] It should be noted that in order to ensure that all the battery cells 10 can be firmly adsorbed on the outer periphery of the drum, the through holes can be evenly distributed in large quantities on the drum wall, so that the battery cells 10 cover multiple through holes under the action of the adsorption force generated inside the drum, and the adsorption force of the multiple through holes can firmly adsorb the battery cells 10 on the outer periphery of the drum.

[0080] It is understood that the cell array 120 may include two cells 10, three cells 10, or a greater number of cells 10, the specific number of cells 10 requiring series connection by solder ribbons can be determined according to the actual usage. Furthermore, in this embodiment, the size and type of the cells 10 are not limited; adjacent cells 10 may have the same or different specifications and dimensions to meet different needs.

[0081] In this disclosure, the specific arrangement of adjacent solar cells 10 is not limited to meet different needs. In one embodiment, the edges of two adjacent solar cells 10 are at least partially stacked together; in another embodiment, two adjacent solar cells 10 may be spaced apart. A suitable spacing between two adjacent solar cells 10 can avoid insufficient operating space and difficult welding due to too small a spacing, and can also avoid wasted component space and increased costs due to too large a spacing.

[0082] After the first battery preform with multi-turn battery cell pack 120 is placed on the outer periphery of the column 110, step S3 is performed: as shown in Figures 6 to 10, a solder ribbon 201 is wound around the outer periphery of the first battery preform, and the angle between the winding direction B of the solder ribbon 201 and the first circumferential direction A is an acute angle, so that the solder ribbon 201 contacts each battery cell 10. Figures 9 and 10 are partial schematic diagrams of region X in Figure 6.

[0083] In step S3 above, actively setting the winding direction B of the welding ribbon 201 at an acute angle to the circumferential direction of the battery cell 10 around the outer periphery of the column 110 reduces the process difficulty of back-contacting the battery assembly 100, reduces alignment requirements during welding, improves welding error tolerance and accuracy, and reduces manufacturing complexity. The tilted setting facilitates the operation of automated equipment, improves production efficiency, reduces manual intervention, and lowers production costs. The acute-angled welding ribbon design helps disperse mechanical stress, reduces stress concentration at the welding point, and improves the reliability and durability of the welding point.

[0084] In some alternative implementations, the angle α between the first circumferential direction A and the winding direction B of the solder strip satisfies the following relationship: 0<tanα≤D / L; where L is the total length between the outer end face of the first cell 10 and the outer end face of the last cell 10 along the first circumferential direction A in the same cell group, and D is the width of any doped layer of the cell 10 along the second direction.

[0085] In the above-described optional embodiments, the tilt angle of the solder ribbon 201 can be determined according to the required length of the battery string 200. The angle can be adjusted for battery strings 200 of different lengths and types so that one solder ribbon 201 can completely cover the doped layer on the same straight line of multiple battery cells 10. This facilitates the fabrication process, whereby after the solder ribbon 201 is divided to connect multiple battery cells 10 in series, it is then selectively sheared by laser to form battery strings 200 in pairs.

[0086] Specifically, the tilt angle of the solder ribbon 201 is flexibly adjusted according to the required length of the battery string 200 and the width of the doped layer to adapt to the specific needs of different battery strings 200, ensuring that the solder ribbon 201 can completely cover the doped layer. Then, by accurately calculating the included angle α, the solder ribbon 201 can extend in a straight line when covering the doped layer, improving welding efficiency and consistency. One solder ribbon 201 can completely cover the doped layer of multiple battery cells 10 on the production line, simplifying the welding process, reducing welding steps, and improving production efficiency. After dividing the solder ribbon 201 to connect multiple battery cells 10 in series, they can be selectively sheared by laser to form pairs of battery strings 200. This method is efficient and precise, reducing the complexity of the production process.

[0087] For example, the required battery string 200 consists of nine battery cells 10 evenly distributed along a first direction. That is, each ring of battery cells surrounding the outer periphery of the column along the first circumferential direction has nine battery cells 10, and L is the distance between the farthest ends of the nine battery cells 10. Based on this length and the width of the doped layer in the second direction, an inclination angle α is calculated, allowing the solder strip to be tilted at an angle α.

[0088] In this embodiment, the angle range between the first circumferential direction A of the battery cell 10 and the winding direction B of the solder ribbon is not limited to meet different requirements. Thus, the length of the battery string 200 and the width of the doped layer in the second direction can be adjusted according to the desired length.

[0089] Furthermore, the widths of the first doped layer 123 and the second doped layer 124 are equal in the second direction. Thus, the first doped layer 123 and the second doped layer 124 can be distributed, allowing the solder ribbon 201 to be uniformly disposed on the back surface 12. This ensures that after the solder ribbon 201 is broken, it can be disposed on the corresponding doped layer. The uniform distribution of the doped layers and the uniform coverage of the solder ribbon 201 on the back surface 12 ensure uniform current conduction.

[0090] Furthermore, the minimum vertical distance H1 between the solder ribbons 201 located on the outer periphery of adjacent solar cell groups is equal; the center distance H2 between two adjacent doped layers is equal; H1 = H2. Thus, after the doped layers are uniformly distributed on the back surface 12 of the solar cell 10, the solder ribbons 201 can also be uniformly distributed on the back surface 12 of the solar cell 10. After dividing the solder ribbons 201 into sub-solder ribbons, the sub-solder ribbons and doped layers can be precisely matched, ensuring that each doped layer can be effectively connected to the sub-solder ribbons.

[0091] Furthermore, when grid lines are provided on the back surface 12 of the solar cell 10, the minimum vertical distance H3 between any two adjacent grid lines in the solar cell 10 is equal; H1 = H3. Thus, after the grid lines are evenly distributed on the back surface 12 of the solar cell 10, the solder ribbons 201 can also be evenly distributed on the back surface 12 of the solar cell 10. After dividing the solder ribbons 201 into sub-strips, the sub-strips and grid lines can be precisely matched, ensuring that each grid line can effectively connect to the sub-strips.

[0092] Furthermore, in this embodiment, "equal center distance" means that "the distance between the structural centers of two adjacent structures is equal to the distance between the structural centers of two other adjacent structures." In manufacturing processes, "equal" can mean an allowable error ratio between 0.9 and 1.1. That is, when the rated center distance is 1, the maximum error distance can be 1.1 times the rated distance, and the minimum error distance can be 0.9 times the rated distance.

[0093] In this embodiment of the disclosure, the minimum vertical distance H1 between the solder strips 201 located on the outer periphery of adjacent battery cell groups is not limited, in order to meet different requirements. For example, the minimum vertical distance H1 between the solder strips 201 located on the outer periphery of adjacent battery cell groups can be ≥100μm, and exemplarily, H1 = 300μm.

[0094] In some alternative embodiments, where a first grid line 121 and a second grid line 122 are provided on the back side 12 of the solar cell 10, the solder ribbon 201 is elongated, and the width of the solder ribbon 201 is smaller than the spacing between the first grid line 121 and the second grid line 122. This avoids the solder ribbon 201 from simultaneously crossing two grid lines of a single solar cell 10, thus preventing a short circuit.

[0095] Specifically, the width of the solder ribbon 201 is designed to be smaller than the spacing between the first grid line 121 and the second grid line 122, ensuring that the solder ribbon 201 does not simultaneously cross and connect two adjacent grid lines. By controlling the width of the solder ribbon 201, the solder ribbon 201 is prevented from simultaneously crossing two grid lines of a single cell 10, thereby preventing short circuits and ensuring the safe and stable operation of the cell 10.

[0096] Referring to Figures 9 and 10, in some optional embodiments, the solder ribbon 201 includes a first solder ribbon segment 210 and a second solder ribbon segment 220 located on the outer periphery of each coil of the battery cell assembly. The first solder ribbon segment 210 and the second solder ribbon segment 220 are alternately connected along the winding direction. The first solder ribbon segment 210 covers and connects the first doped layer 123 or the first grid line 121 of the first battery cell 101 and the second doped layer 124 or the second grid line 122 of the second battery cell 102. The second solder ribbon segment 220 covers and connects the second doped layer 124 or the second grid line 122 of the first battery cell 101 and the first doped layer 123 or the first grid line 121 of another second battery cell 102. Thus, after the solder ribbon 201 is divided into sub-strips, the first solder ribbon segment 210 and the second solder ribbon segment 220 can be sequentially coupled to connect multiple first battery cells 101 and multiple second battery cells 102 in series to form a battery string.

[0097] After the solder ribbon 201 is wrapped around the outer periphery of the first battery preform, step S4 is performed: as shown in Figures 11 to 13, the solder ribbon is divided into multiple sub-solder ribbons 20 along the target position so that each sub-solder ribbon 20 connects the first doped layer 123 of different battery cells 10 and the second doped layer 124 of adjacent battery cells 10, and multiple battery cells 10 are connected in series through the sub-solder ribbons 20 to form a battery string 200.

[0098] Specifically, as shown in Figures 5 to 12, the area between the first and last battery cell 10 along the first circumferential direction A in the same ring of battery cell group 120 can be defined as the first target area Y. The solder ribbon 201 is divided along the position corresponding to all the first target areas Y to obtain multiple second battery preforms. Each second battery preform includes all the battery cells 10 in a ring of battery cell group 120. The battery cells 10 in each second battery preform are distributed along the first direction. Then, the gap between adjacent battery cells 10 in each ring of battery cell group 120 can be defined as the second target area. The solder ribbon 201 is divided into sub-solder ribbons 20 along the position corresponding to the multiple second target areas so that the sub-solder ribbons 20 extend along the third direction and are alternately distributed along the second direction. Each sub-solder ribbon 20 connects the first doped layer 123 of different battery cells 10 and the second doped layer 124 of adjacent battery cells 10. The angle between the first direction and the third direction is an acute angle.

[0099] After obtaining multiple second battery preforms, or after dividing the welding strip 201 into sub-welding strips 20, the preparation method of this embodiment may further include: as shown in FIG8, adsorbing the busbar structure 30 onto the outer periphery of the column 110 so that the busbar structure 30 is located between the first battery cell 10 and the last battery cell 10 in the same ring of battery cell group 120 along the first circumferential direction A.

[0100] Specifically, the aforementioned bus structure 30 can be used to connect solder strips of the same polarity, thereby forming a circuit with the battery string 200 to discharge current energy. In this embodiment, the form of the bus structure 30 is not limited to meet different needs. For example, the bus structure 30 can be a conductive material such as a wire, busbar, or conductive tape.

[0101] After dividing the solder ribbon 201 into sub-solder ribbons 20, the first doped layer 123 of the solar cell 10 and the second doped layer 124 of an adjacent solar cell 10 can be connected together through the sub-solder ribbons 20. Simultaneously, the second doped layer 124 of the solar cell 10 and the first doped layer 123 of another adjacent solar cell 10 can be connected together through the sub-solder ribbons 20. That is, multiple solar cells 10 can be connected in series through the sub-solder ribbons 20 to form a battery string 200 distributed along a first direction. Of course, in some embodiments, the sub-solder ribbon 20 located at the end of the battery string 200 may only connect to one doped layer and extend relative to the solar cell 10 to connect to structures such as busbars.

[0102] After dividing the solder ribbon 201 into sub-strips 20, the sub-strips 20 are disposed on at least two solar cells 10 in a third direction, electrically connecting the first doped layer 123 of the solar cell 10 and the second doped layer 124 of the adjacent solar cell 10, respectively. The sub-strips 20 are alternately distributed in a second direction to connect the dissimilar doped layers of adjacent solar cells 10 to form a battery string 200, wherein the angle between the first direction and the third direction is an acute angle. By setting the sub-strips 20 at an acute angle to the doped layers, the contact area between the sub-strips 20 and the solar cells 10 is significantly increased, thereby improving the electrical contact area between the sub-strips 20 and the doped layers and enhancing the conductivity efficiency. At the same time, the inclined design of the sub-strips 20 can effectively alleviate the stress concentration problem, ensure the stability of the connection between the sub-strips 20 and the solar cells 10, and reduce connection failures caused by mechanical stress or temperature changes. The firm connection between the sub-strips 20 and the doped layers ensures a stable electrical connection between the solar cells 10, improving the reliability and service life of the back contact battery assembly 100.

[0103] When a first grid line 121 and a second grid line 122 are provided on the back side 12 of the solar cell 10, the first grid line 121 and the second grid line 122 are alternately distributed on the back side 12 of the solar cell 10. The first grid line 121 is independently provided on the first doped layer 123, and the second grid line 122 is independently provided on the second doped layer 124. The sub-soldering ribbon 20 covers the first grid line 121 and the second grid line 122 of the adjacent solar cell 10. The sub-soldering ribbon 20 enables current convergence between multiple solar cells 10, ensuring efficient current conduction.

[0104] Specifically, during the manufacturing process, a single welding ribbon 201 can be simultaneously placed on the same straight grid line of multiple solar cells 10, and then disconnected at a target location to ensure that the divided sub-welding ribbons 20 can connect the first grid line 121 and the second grid line 122 of adjacent solar cells 10. For example, the sub-welding ribbon 20 can connect the first grid line 121 of the first solar cell 10 and the second grid line 122 of the second solar cell 10, and then disconnect at the end of the second grid line 122 of the second solar cell 10 away from the first solar cell 10. Similarly, the sub-welding ribbon 20 can connect the first grid line 121 of the second solar cell 10 and the second grid line 122 of the third solar cell 10, and then disconnect at the end of the second grid line 122 of the third solar cell 10 away from the second solar cell 10. This process continues to form a continuous string of solar cells 200.

[0105] Furthermore, in the fabrication process of the battery string 200, the sub-welding ribbon 20 can cover multiple battery cells 10 on the same straight grid line in a single step along a third direction, improving welding efficiency, reducing welding steps and time, and making it suitable for mass production. The design of attaching the sub-welding ribbon 20 to the grid line at a certain angle facilitates automated equipment operation and improves production accuracy and consistency. The connection between the sub-welding ribbon 20 and the grid line increases the mechanical strength and stability of the back contact battery assembly 100, extending its service life.

[0106] Furthermore, the multiple sub-weld ribbons 20 are arranged in parallel; the first grid line 121, the second grid line 122, the first doped layer 123, and the second doped layer 124 are also arranged in parallel. Thus, the grid lines and doped layers are arranged in parallel on the back surface 12 of the solar cell 10, making the solar cell 10 more uniform overall. The multiple sub-weld ribbons 20 are arranged in parallel on the back surface 12 of the solar cell and evenly distributed in a direction perpendicular to the third direction, ensuring consistent spacing between the sub-weld ribbons 20 and forming a regular layout. This also allows the sub-weld ribbons 20 to be arranged correspondingly to the grid lines or doped layers.

[0107] Please refer to Figures 11 and 12. In some alternative embodiments, the sub-welding strip 20 includes a first side 23 and a second side 24, both of which extend along a third direction. On any cell 10, the first side 23 includes a starting segment 231 and a tail segment 232, and the distance between the grid line and the starting segment 231 is greater than the distance between the grid line and the tail segment 232.

[0108] Thus, the sub-welding strip 20 is arranged along a third direction on each cell 10, and the position of the sub-welding strip 20 on the first side 23 of any cell 10 is different from that of the grid line, so that the sub-welding strip 20 can cover the grid line and improve the connection capability with the grid line.

[0109] Specifically, the sub-welding strip 20 is also rectangular, with the first side 23 and the second side 24 both arranged along a third direction. This arrangement ensures that the sub-welding strip 20 covers the grid lines, increasing the contact area between the sub-welding strip 20 and the grid lines, and improving current conduction efficiency. The starting segment 231 and the ending segment 232 of the sub-welding strip 20 are at different distances from the grid lines, ensuring the optimal position of the sub-welding strip 20 on the cell 10 and improving the connection capability and stability between the sub-welding strip 20 and the grid lines.

[0110] Referring to Figures 11 and 12, in some optional embodiments, the sub-strip 20 includes a first solder strip 21 and a second solder strip 22. The first solder strip 21 and the second solder strip 22 extend along a third direction and are alternately distributed along a second direction. The first solder strip 21 corresponds to the first solder strip segment 210 of the sub-strip in step S3, and the second solder strip 22 corresponds to the second solder strip segment 220 of the sub-strip in step S3. The first solder strip 21 covers and connects the first doped layer 123 or the first grid line 121 of the first solar cell 101 and the second doped layer 124 or the second grid line 122 of the second solar cell 102. The second solder strip 22 covers and connects the second doped layer 124 or the second grid line 122 of the first solar cell 101 and the first doped layer 123 or the first grid line 121 of another second solar cell 102. In this way, the first solder strip 21 and the second solder strip 22 can be sequentially coupled to connect multiple first solar cells 101 and multiple second solar cells 102 in series to form a battery string 200.

[0111] Referring to Figures 11 and 12, in some optional embodiments, the distance between the starting segment 231 and the first edge 13 of the battery cell 10 is less than the distance between the ending segment 232 and the first edge 13 of the battery cell 10. Thus, the sub-welding strips 20 on the battery cell 10 are inclined relative to the edge of the battery cell 10, the starting segment 231 and the ending segment are at different distances from the first edge 13, and the sub-welding strips 20 can cover the corresponding grid lines, ensuring a stable connection with the grid lines.

[0112] Specifically, the starting segment 231 of the sub-welding ribbon 20 located on the same solar cell 10 is closer to the first edge 13 of the solar cell 10, while the ending segment 232 of the sub-welding ribbon 20 is farther from the first edge 13 of the solar cell 10. This arrangement of the sub-welding ribbon 20 on the solar cell 10 results in the sub-welding ribbon 20 being tilted relative to the first edge 13 of the solar cell 10. The starting segment 231 and the ending segment 232 of the sub-welding ribbon 20 cover the corresponding grid lines, ensuring the stability of current conduction. At the same time, the tilted arrangement of the sub-welding ribbon 20 relative to the solar cell 10 increases the contact area between the sub-welding ribbon 20 and the grid lines, ensuring the stability and efficiency of current conduction. Since both the starting segment 231 and the ending segment 232 of the sub-welding ribbon 20 cover the grid lines, it effectively prevents the sub-welding ribbon 20 from breaking off from the grid lines, improving the reliability of the connection. In addition, the tilted arrangement of the sub-welding ribbon 20 relative to the edge of the solar cell 10 allows for flexible adjustment of the contact position between the sub-welding ribbon 20 and the grid lines, adapting to different types and sizes of solar cells 10. The inclined sub-welding strip 20 can effectively disperse mechanical stress, reduce weld point damage caused by stress concentration, and extend the service life of the back contact battery assembly 100.

[0113] For example, referring to Figures 11 to 13, the back contact battery assembly 100 obtained by the above-described preparation method of the present disclosure includes a battery string 200 and sub-welding strips 20. The battery string 200 includes a plurality of battery cells 10. Each battery cell 10 has a front side 11 and a back side 12. The back side 12 is provided with a first doped layer 123 and a second doped layer 124. The first doped layer 123 and the second doped layer 124 extend along a first direction and are alternately distributed along a second direction, wherein the first direction and the second direction intersect. The sub-welding strips 20 are disposed on at least two battery cells 10 and electrically connect the first doped layer 123 of the battery cell 10 and the second doped layer 124 of the adjacent battery cell 10, respectively. The sub-welding strips 20 extend along a third direction and are alternately distributed along the second direction, wherein the angle between the first direction and the third direction is an acute angle, and the doping polarities of the first doped layer 123 and the second doped layer 124 are opposite.

[0114] In the back contact battery assembly 100 of this disclosure embodiment, the back contact battery assembly 100 includes a battery string 200 and a sub-soldering ribbon 20. The battery string 200 includes a plurality of battery cells 10. Each battery cell 10 has a front side 11 and a back side 12. The back side 12 is provided with a first doped layer 123 and a second doped layer 124. The first doped layer 123 and the second doped layer 124 extend along a first direction and are alternately distributed along a second direction, wherein the first direction and the second direction intersect. The sub-soldering ribbon 20 is disposed on at least two battery cells 10 and electrically connects the first doped layer 123 of the battery cell 10 and the second doped layer 124 of the adjacent battery cell 10, respectively. The sub-soldering ribbon 20 extends along a third direction and is alternately distributed along the second direction, wherein the angle between the first direction and the third direction is an acute angle, and the doping polarities of the first doped layer 123 and the second doped layer 124 are opposite. In this way, by setting the sub-solder strip 20 at an acute angle to the doped layer, the contact area between the sub-solder strip 20 and the solar cell 10 can be increased, thereby increasing the electrical contact area between the sub-solder strip 20 and the doped layer and improving the conductivity efficiency from the doped layer to the sub-solder strip 20. At the same time, the inclined setting of the sub-solder strip 20 can alleviate the problem of stress concentration, so as to ensure the stable connection between the sub-solder strip 20 and the solar cell 10 and improve the connection stability between the sub-solder strip 20 and the solar cell 10.

[0115] The welding strip is then divided into multiple sub-welding strips along the target position, and multiple battery cells are connected in series through the sub-welding strips to form a battery string. The preparation method in this embodiment may further include: placing an adhesive film and a backing plate on the side of the battery cell 10 where the sub-welding strips 20 are provided to form a laminate; framing and installing the laminate, and welding a junction box to form a back contact battery assembly 100.

[0116] For example, the solder strips at the target location are cut by laser cutting or other techniques to form a series battery string 200. The battery string 200 is placed between the front panel and the back panel. The battery string 200 is bonded to the front panel by a front adhesive film and to the back panel by a back adhesive film. The back adhesive film and the back panel are located on the side of the battery cell 10 where the sub-solder strips 20 are provided to form a laminate. Finally, the laminate is framed and installed, and a junction box is welded to form a back contact battery assembly 100.

[0117] Please refer to Figure 14. The photovoltaic system 300 provided in this embodiment includes a back contact battery module 100 prepared using any of the above embodiments.

[0118] Specifically, as shown in Figures 11 to 14, in the back contact battery module 100 and its preparation method and photovoltaic system 300 of the present disclosure, the back contact battery module 100 includes a battery string 200 and sub-welding strips 20. The battery string 200 includes a plurality of battery cells 10. The battery cells 10 have opposing front sides 11 and back sides 12. The back side 12 is provided with a first doped layer 123 and a second doped layer 124. The first doped layer 123 and the second doped layer 124 extend along a first direction and are alternately distributed along a second direction, wherein the first direction and the second direction intersect. The sub-welding strips 20 are disposed on at least two battery cells 10 and electrically connect the first doped layer 123 of the battery cell 10 and the second doped layer 124 of the adjacent battery cell 10, respectively. The sub-welding strips 20 extend along a third direction and are alternately distributed along the second direction, wherein the angle between the first direction and the third direction is an acute angle, and the doping polarities of the first doped layer 123 and the second doped layer 124 are opposite. In this way, by setting the sub-solder strip 20 at an acute angle to the doped layer, the contact area between the sub-solder strip 20 and the solar cell 10 can be increased, thereby increasing the electrical contact area between the sub-solder strip 20 and the doped layer and improving the conductivity efficiency from the doped layer to the sub-solder strip 20. At the same time, the inclined setting of the sub-solder strip 20 can alleviate the problem of stress concentration, so as to ensure the stable connection between the sub-solder strip 20 and the solar cell 10.

[0119] In this embodiment, the photovoltaic system 300 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 for power generation, 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 300 are not limited to these; that is, the photovoltaic system 300 can be applied in all fields that require solar energy for power generation. Taking a photovoltaic power generation system grid as an example, the photovoltaic system 300 may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple back-contact battery modules 100. For example, multiple back-contact battery modules 100 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.

[0120] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0121] The above are merely embodiments of this disclosure and are not intended to limit the scope of this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of the claims of this disclosure.

Claims

1. A method for preparing a back-contact battery assembly, comprising the following steps: A plurality of solar cells are provided, the solar cells having opposing front and back sides, the back side having a first doped layer and a second doped layer with opposite doping polarities, the first doped layer and the second doped layer extending along a first direction and alternately distributed along a second direction, wherein the first direction and the second direction intersect. The battery cells are wrapped around the outer periphery of the column multiple times along the first circumferential direction to obtain a first battery preform with multiple battery cell groups, and adjacent battery cell groups are spaced apart along the height direction of the column. The welding strip is wound around the outer periphery of the first battery preform, and the angle between the winding direction of the welding strip and the first circumferential direction is an acute angle, so that the welding strip contacts each of the battery cells; The solder strip is divided into multiple sub-strips along the target position, so that each sub-strip is electrically connected to the first doped layer of a different solar cell and the second doped layer of an adjacent solar cell, and multiple solar cells are connected in series through the sub-strips to form a battery string.

2. The preparation method according to claim 1, wherein, Any two adjacent cells in the same circle of the cell group have the same spacing, or at least some of any two adjacent cells in the same circle of the cell group are stacked.

3. The preparation method according to claim 1, wherein, Any two adjacent rings of the battery cell array have the same spacing.

4. The preparation method according to claim 1, wherein, The steps for obtaining the first battery preform include: Multiple battery cells are grouped together, and each group of battery cells is sequentially adsorbed onto the outer periphery of the column along the first circumferential direction to form multiple rings of battery cell groups spaced apart along the height direction of the column.

5. The preparation method according to claim 4, wherein, The column is a roller with multiple through holes distributed on its cylindrical wall. The inside of the roller is connected to a vacuum pumping device. When the vacuum pumping device is in operation, the through holes have an adsorption force. In the step of setting the battery cells on the outer periphery of the column, the roller is rotated along the first circumferential direction under the drive of the drive device, so that each battery cell is sequentially adsorbed onto the cylinder wall under the action of the adsorption force.

6. The preparation method according to claim 5, wherein, In the step of winding the welding strip around the first battery preform, the roller rotates along the first circumferential direction under the drive of the drive device, so that the welding strip is sequentially wound onto the outer surface of each turn of the battery cell assembly under the drive of the roller.

7. The preparation method according to claim 1, wherein, The angle α between the first circling direction and the winding direction of the welding strip satisfies the following relationship: 0<tanα≤D / L; Wherein, L is the total length between the outer end face of the first and last solar cells in the same solar cell group along the first circumferential direction, and D is the width of any doped layer of the solar cell along the second direction.

8. The preparation method according to claim 1, wherein, The minimum vertical distance H1 between the solder strips located on the outer periphery of adjacent battery cell groups is equal; the center distance H2 between two adjacent doped layers is equal; H1 = H2.

9. The preparation method according to claim 1, wherein, The step of dividing the solder strip into multiple sub-strips along the target position includes: The area between the first and last battery cell in the same ring of the battery cell group along the first circumferential direction is defined as the first target area, and the solder strip is divided along the position corresponding to all the first target areas to obtain a plurality of second battery preforms. Each second battery preform includes all the battery cells in a ring of the battery cell group, and the battery cells in each second battery preform are distributed along the first direction. The gap between adjacent cells in each ring of the cell array is defined as a second target region, and the solder ribbon is divided into sub-solder ribbons along the positions corresponding to the multiple second target regions, so that the sub-solder ribbons extend along a third direction and are alternately distributed along the second direction. Each sub-solder ribbon connects the first doped layer of a different cell and the second doped layer of an adjacent cell, wherein the angle between the first direction and the third direction is an acute angle.

10. The preparation method according to claim 9, wherein, Also includes: The busbar structure is adsorbed onto the outer periphery of the column so that the busbar structure is located between the first and last battery cells in the same ring of the battery cell group along the first circumferential direction.

11. The preparation method according to claim 1, wherein, The widths of the first doped layer and the second doped layer are equal in the second direction.

12. The preparation method according to claim 1, wherein, The back side is provided with gate lines, the gate lines include a first gate line and a second gate line, the first gate line and the second gate line extend along the first direction and are alternately distributed along the second direction, the first gate line is disposed on the first doped layer, and the second gate line is disposed on the second doped layer; Each of the sub-strips covers the first grid line of a different solar cell and the second grid line of an adjacent solar cell.

13. The preparation method according to claim 12, wherein, The minimum vertical distance H1 between the solder strips located on the outer periphery of adjacent battery cell groups is equal; the minimum vertical distance H3 between any adjacent grid lines in the battery cell is equal; H1 = H3.

14. The preparation method according to claim 12, wherein, In the same ring of the battery cell array, the first grid line, the second grid line, the first doped layer, and the second doped layer are all arranged in parallel.

15. The preparation method according to claim 12, wherein, The sub-welding strip includes a first side and a second side, both of which extend along a third direction. On any of the battery cells, the first side includes a starting segment and a tail segment. The distance between the grid line and the starting segment is greater than the distance between the grid line and the tail segment. The angle between the third direction and the first direction is an acute angle.

16. The preparation method according to claim 15, wherein, The battery cells are all rectangular in shape. Each battery cell includes a first battery cell and a second battery cell arranged sequentially along the first direction. Each battery cell includes a first edge and a second edge distributed along the second direction. The grid line of the first battery cell closest to the first edge is the first grid line, and the grid line of the second battery cell closest to the first edge is the second grid line.

17. The preparation method according to claim 16, wherein, The distance between the starting segment and the first edge of the battery cell is less than the distance between the tail segment and the first edge of the battery cell.

18. The preparation method according to claim 16, wherein, The first edge of the solar cell is arranged parallel to the doped layer or grid lines.

19. The preparation method according to claim 16, wherein, The welding strip includes a first welding strip segment and a second welding strip segment located on the outer periphery of each turn of the battery cell assembly, and the first welding strip segment and the second welding strip segment are alternately connected along the winding direction; The first solder strip segment covers and connects the first doped layer or the first grid line of the first solar cell and the second doped layer or the second grid line of the second solar cell; The second solder strip covers and connects the second doped layer or the second grid line of the first solar cell to the first doped layer or the first grid line of another second solar cell.

20. The preparation method according to claim 12, wherein, The solder strip is elongated and its width is less than the spacing between the first grid line and the second grid line of any one of the battery cells.

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