Back contact cell string, cell assembly and photovoltaic system
By designing a first and second protrusion at the edge of the back contact cell, and using a stepped protrusion and groove structure, the problems of light leakage and microcracks in the back contact cell module are solved, thereby improving power generation efficiency and cell module yield.
Patent Information
- Application Number
- CN202520263144.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-18
- Publication Date
- 2025-11-28
- Estimated Expiration
- 2035-02-18
AI Technical Summary
In the prior art, during the lamination and encapsulation process of back contact battery modules, the gap between adjacent contact cells can lead to light leakage and limited power generation of the battery module. In the prior art, the spacing between back contact cells results in severe light leakage and microcracks and fragmentation between cells.
By designing a first protrusion and a second protrusion at the edge of the back contact cell and stacking them together, the height difference between the back contact cells is reduced. The stepped protrusion and groove structure ensures that the cell surface is flush and avoids stress concentration.
It effectively reduces light leakage, increases power generation per unit area, reduces microcracks and fragmentation, and improves the yield of battery modules.
Smart Images
Figure CN223613756U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of solar cell technology, and more particularly to a back-contact cell string, cell module and photovoltaic system. Background Technology
[0002] In solar cells, a back-contact cell is a type of cell in which both the emitter and base contact electrodes are placed on the back of the cell (the non-light-receiving surface). The light-receiving surface of this cell is not blocked by any metal electrodes, which effectively increases the short-circuit current of the cell.
[0003] Currently, back-contact battery modules consist of multiple cell strings. In conventional battery modules, there is a gap between two adjacent back-contact cells in the cell string. These gaps can cause light leakage and also limit the power generation per unit area of the battery module.
[0004] In related technologies, to solve such technical problems, adjacent back-contact cells are usually set with negative spacing (that is, the edges of the two cells overlap) in the cell string. However, in such technical solutions, since the two adjacent back-contact cells need to be partially overlapped, there is a high height difference. During the module lamination and encapsulation process, edge stress concentration is likely to occur, resulting in microcracks and fragmentation, leading to a high fragmentation rate of the module. Utility Model Content
[0005] This application provides a back-contact battery string, a battery module, and a photovoltaic system.
[0006] This application is implemented as follows: the back contact battery string of this application embodiment includes a plurality of back contact battery pieces, each of which has a first surface and a second surface opposite to each other, and the first surfaces of all the back contact battery pieces are oriented in the same way.
[0007] The back contact battery cells include a plurality of first battery cells and a plurality of second battery cells. The plurality of first battery cells and the plurality of second battery cells are arranged alternately and connected in series along a first direction. A first protrusion is formed on the edge of the first battery cell facing the second battery cell, and a second protrusion is formed on the edge of the second battery cell facing the first battery cell. The second protrusion and the first protrusion are stacked and fitted together so that the height difference between the first surface of the first battery cell and the first surface of the second battery cell is less than the thickness of the back contact battery cell.
[0008] In some embodiments, the first protrusion and the second protrusion have only silicon wafer portions and do not have metal electrodes on the first protrusion and the second protrusion.
[0009] In some embodiments, the first surface of the first cell sheet is flush with the first surface of the second cell sheet, and the second surface of the first cell sheet is flush with the second surface of the second cell sheet.
[0010] In some embodiments, the height difference between the first surface of the first cell sheet and the first surface of the second cell sheet is 90-150 um, and the height difference between the second surface of the first cell sheet and the second surface of the second cell sheet is 90-150 um.
[0011] In some embodiments, the length of the portion where the first protrusion and the second protrusion are stacked and fitted in the first direction is less than 2 mm.
[0012] In some embodiments, the first protrusion is a stepped protrusion, and the second protrusion is also a stepped protrusion.
[0013] In some embodiments, the first surface of the first cell sheet is formed with a first groove toward the edge of the side of the second cell sheet to form the first protrusion, the second surface of the second cell sheet is formed with a second groove toward the edge of the side of the first cell sheet to form the second protrusion, the first protrusion is fitted in the second groove, and the second protrusion is fitted in the first groove to make the first protrusion and the second protrusion stacked and fitted with each other.
[0014] In some embodiments, when the first cell sheet has the second cell sheet on both sides, the first surface of the first cell sheet is formed with the first groove and the first protrusion on both side edges in the first direction, and when the second cell sheet has the first cell sheet on both sides, the second surface of the second cell sheet is formed with the second groove and the second protrusion on both side edges in the first direction.
[0015] In some embodiments, in the thickness direction of the back contact cell sheet, the depth of the first groove and the depth of the second groove are both 45-80 um.
[0016] In some embodiments, the sum of the depth of the first groove and the depth of the second groove is equal to the thickness of the back contact cell sheet.
[0017] In some embodiments, the first protrusion is a stepped protrusion, and the second protrusion is also a stepped protrusion.
[0018] When the first cell has the second cell on both sides, a first surface of the first cell forms a third groove towards an edge of a side of one of the second cells to form one of the first protrusions, and a second surface of the first cell forms a fourth groove towards a surface of a side of another of the second cells to form another of the first protrusions;
[0019] When the second cell has the first cell on both sides, a first surface of the second cell forms a fifth groove towards an edge of a side of one of the first cells to form one of the second protrusions, and a second surface of the second cell forms a sixth groove towards a surface of a side of another of the first cells to form another of the second protrusions.
[0020] In some embodiments, in a thickness direction of the back contact cell, the third groove, the fourth groove, the fifth groove and the sixth groove each has a depth of 45um-80um.
[0021] In some embodiments, in a thickness direction of the back contact cell, a depth of one of the third groove and the fourth groove and a depth of one of the fifth groove and the sixth groove are equal to a sum of the thickness of the back contact cell.
[0022] In some embodiments, the first cell includes a first side surface facing the second cell, the first side surface is a bevel to form the first protrusion on the first cell, the second cell includes a second side surface facing the first cell, the second side surface is also a bevel to form the second protrusion on the second cell, and the second side surface cooperates with the first side surface to make the first protrusion and the second protrusion stack and fit with each other.
[0023] In some embodiments, one of the first side surface and the second side surface forms an acute angle with the first surface, the other forms an obtuse angle with the first surface, and a sum of the angle between the first side surface and the first surface and the angle between the second side surface and the first surface is 180°.
[0024] The application also provides a battery assembly, which includes a plurality of the back contact cell strings as described above.
[0025] The application also provides a photovoltaic system, which includes the battery assembly as described above.
[0026] In the back contact cell string, the cell assembly and the photovoltaic system provided in the embodiments of the present application, in the stringing direction of the back contact cell string, the edge of the side of the first cell piece facing the second cell piece is formed with a first protrusion, the edge of the side of the second cell piece facing the first cell piece is formed with a second protrusion, and the second protrusion and the first protrusion are stacked and fitted with each other. In this way, by the stacked arrangement of the first protrusion and the second protrusion, the light leakage can be reduced, the power generation power per unit area is improved, and at the same time, the height difference between the adjacent two back contact cell pieces can be reduced or even eliminated, so as to effectively reduce the phenomenon of hidden cracks and fragments.
[0027] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 is a schematic diagram of a module of a photovoltaic system provided in the embodiments of the present application;
[0029] Figure 2 is a schematic diagram of a cell assembly provided in the embodiments of the present application;
[0030] Figure 3 is a schematic diagram of a structure of a back contact cell string provided in the embodiments of the present application;
[0031] Figure 4 is Figure 3 is an exploded schematic diagram of the back contact cell string in
[0032] Figure 5 is another schematic diagram of a back contact cell string provided in the embodiments of the present application;
[0033] Figure 6 is Figure 5 is an exploded schematic diagram of the back contact cell string in
[0034] Figure 7 is still another schematic diagram of a back contact cell string provided in the embodiments of the present application;
[0035] Figure 8 is Figure 7 is an exploded schematic diagram of the back contact cell string in
[0036] Figure 9 is still another schematic diagram of a back contact cell string provided in the embodiments of the present application;
[0037] Figure 10 is Figure 9 is an exploded schematic diagram of the back contact cell string in
[0038] Main element symbol explanation:
[0039] Photovoltaic system 1000, battery assembly 200, back contact cell string 100, back contact cell 10, first surface 101, second surface 102, first cell 11, first protrusion 111, second cell 12, second protrusion 121, first groove 13, second groove 14, third groove 15, fourth groove 16, fifth groove 17, sixth groove 18, first side 19, second side 120. DETAILED DESCRIPTION
[0040] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and cannot be used to limit the present application.
[0041] In the description of the present application, it should be understood that the terms "length", "width", "upper", "lower", "lateral", "longitudinal" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.
[0042] In addition, the terms "first", "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.
[0043] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0044] In the present application, unless specifically defined and limited otherwise, "on" or "under" of a first feature with respect to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "over", "above", and "on" of a first feature with respect to a second feature includes that the first feature is directly above and obliquely above the second feature, or only means that the first feature is horizontally higher than the second feature. "Under", "below", and "under" of a first feature with respect to a second feature includes that the first feature is directly below and obliquely below the second feature, or only means that the first feature is horizontally lower than the second feature.
[0045] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplification, the components and arrangements of specific examples are described in the following. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.
[0046] Please refer to Figures 1-2 The photovoltaic system 1000 in the embodiments of the present application can include the battery assembly 200 in the embodiments of the present application, the battery assembly 200 in the embodiments of the present application can include a plurality of back contact cell strings 100 in the embodiments of the present application, and the back contact cell string 100 can include a plurality of series-connected back contact cell pieces 10. In the embodiments of the present application, each cell string in the battery assembly 200 can be connected in series, in parallel, or in a combination of series and parallel to realize the current output, for example, the connection between each cell piece can be realized by welding the ribbon, and the connection between each cell string can be realized by the bus bar. In some embodiments, each cell string can form a cell piece array, and then be packaged together by the front plate, the front adhesive film, the rear adhesive film, and the back plate to form the battery assembly 200.
[0047] Please refer to Figure 3 In the back contact cell string 100 in the embodiments of the present application, a plurality of back contact cell pieces 10 can be connected in series along a first direction, each back contact cell piece 10 has opposite first and second surfaces 101 and 102, the first surface 101 of each back contact cell piece 10 in the back contact cell string 100 is oriented in the same direction, and the second surface 102 of each back contact cell piece 10 is also the same.
[0048] That is to say, in the back contact battery string 100, the placing directions of all the back contact battery pieces 10 are the same, the first surfaces 101 of each back contact battery piece 10 all face the same side, and the second surfaces 102 of each back contact battery piece 10 also all face the same side. Specifically, the first surface 101 and the second surface 102 can be the back surface and the front surface of the back contact battery piece 10 respectively, that is, when the first surface 101 is the back surface, the second surface 102 is the front surface, and when the first surface 101 is the front surface, the second surface 102 is the back surface.
[0049] The first direction is the stringing direction of each battery string of the back contact battery string 100. In the embodiment of the present application, each back contact battery piece 10 in the back contact battery string 100 can be sequentially stringed together through a solder strip, and the first direction can be the extension direction of the solder strip.
[0050] Please refer to Figures 3-10 In the embodiment of the present application, in the back contact battery string 100, the plurality of back contact battery pieces 10 include a plurality of first battery pieces 11 and a plurality of second battery pieces 12, the plurality of first battery pieces 11 and the plurality of second battery pieces 12 are alternately arranged and sequentially stringed along the first direction, the first battery piece 11 forms a first protrusion 111 at the edge of the side facing the second battery piece 12, and the second battery piece 12 forms a second protrusion 121 at the edge of the side facing the first battery piece 11. The second protrusion 121 and the first protrusion 111 are stacked and fitted with each other so that the height difference between the first surface 101 of the first battery piece 11 and the first surface 101 of the second battery piece 12 is less than the thickness of the back contact battery piece 10.
[0051] It should be noted that, in this paper, “stacked with each other” means that the first protrusion 111 and the second protrusion 121 are stacked together in the thickness direction (the first protrusion 111 can be stacked above the second protrusion 121, or the second protrusion 121 can be stacked above the first protrusion 111, which is not limited here), and “fitted with each other” means that the structures of the two are matched and fit with each other, and the specific structure of the first protrusion 111 and the second protrusion 121 is not limited here, as long as they can fit with each other.
[0052] In the back contact cell string 100, the cell assembly 200 and the photovoltaic system 1000 in the embodiments of the present application, in the stringing direction of the back contact cell string 100, the edge of the side of the first cell piece 11 facing the second cell piece 12 is formed with a first protrusion 111, the edge of the side of the second cell piece 12 facing the first cell piece 11 is formed with a second protrusion 121, and the second protrusion 121 and the first protrusion 111 are stacked and fitted with each other. In this way, by the stacked arrangement of the first protrusion 111 and the second protrusion 121, the light leakage can be reduced, the power generation per unit area can be improved, and at the same time, the height difference between the two adjacent back contact cell pieces 10 can be reduced or even eliminated, thereby effectively reducing the phenomenon of hidden cracks and fragments.
[0053] Specifically, in the embodiments of the present application, the height difference between the first surface 101 of the first cell piece 11 and the first surface 101 of the second cell piece 12 is less than the thickness of the back contact cell piece 10, and the height difference between the second surface 102 of the first cell piece 11 and the second surface 102 of the second cell piece 12 is also less than the thickness of the back contact cell piece 10. In this way, the height of the stacked portion of the two adjacent back contact cell pieces 10 is small, which can effectively reduce the edge stress concentration, reduce the fragment rate in the laminated packaging process, and improve the yield.
[0054] In the embodiments of the present application, the back contact cell piece 10 can include a silicon wafer, a plurality of P-type doped layers and a plurality of N-type doped layers arranged on the back surface of the silicon wafer, a back passivation film layer arranged on the back surface of the silicon wafer, and a front passivation film layer arranged on the front surface of the silicon wafer. In addition, the back surface of the back contact cell piece 10 has a plurality of positive fine grids and negative fine grids, the positive fine grids are conductively contacted with the P-type doped layers through the back passivation film layer, and the negative fine grids are conductively contacted with the N-type doped layers through the back passivation film layer. The positive fine grids and the negative fine grids extend along a first direction and are alternately and spacedly arranged along a direction intersecting the first direction (for example, a direction perpendicular to the first direction).
[0055] In the embodiments of the present application, the back contact cell piece 10 can be a cell piece with main grids or a cell piece without main grids. When the back contact cell piece 10 is a cell piece with main grids, the back contact cell piece 10 further has a positive main grid connected with the positive fine grids and a negative main grid connected with the negative fine grids, and the positive main grid and the negative main grid can extend along the first direction and are respectively welded with the positive solder ribbon and the negative solder ribbon. When the back contact cell piece 10 is a cell piece without main grids, the positive solder ribbon and the negative solder ribbon can be directly arranged to connect with the positive fine grids and the negative fine grids, respectively, and the specific arrangement is not limited herein.
[0056] Of course, in some embodiments, in the back contact cell string 100, one positive solder ribbon can be correspondingly arranged on each positive fine grid, and one negative solder ribbon can be correspondingly arranged on each negative fine grid, and the specific arrangement is not limited herein.
[0057] In some embodiments, the first protrusion 111 and the second protrusion 121 only have the silicon wafer portion and no metal electrodes (such as the positive electrode fine grid, the negative electrode fine grid, the positive electrode main grid and the negative electrode main grid as described above) are provided on the first protrusion 111 and the second protrusion 121.
[0058] In this way, the first protrusion 111 and the second protrusion 121 can be formed after the back contact battery piece 10 is completely prepared, and the etching or cutting process is performed on the back contact battery piece 10, so that the first protrusion 111 and the second protrusion 121 are formed without adding an additional process to form the first protrusion 111 and the second protrusion 121 in the process of manufacturing the back contact battery piece 10, thereby simplifying the manufacturing process of the back contact battery piece 10.
[0059] Specifically, in such embodiments, the first protrusion 111 and the second protrusion 121 are invalid regions of the back contact battery piece 10, and the first protrusion 111 and the second protrusion 121 only have the silicon wafer portion and no other structures. In this case, in the back contact battery string 100, a conventional stringing method can be used for stringing, which will not be described here.
[0060] In some embodiments, the height difference between the first surface 101 of the first battery piece 11 and the first surface 101 of the second battery piece 12 can be 90um-150um, and the height difference between the second surface 102 of the first battery piece 11 and the second surface 102 of the second battery piece 12 can be 90um-150um. Specifically, through careful research and demonstration by the inventors of the present application, it is found that setting the height difference between the first surface 101 and the second surface 102 of the adjacent two back contact battery pieces 10 within the reasonable range of 90um-150um can effectively reduce the fragment rate and improve the yield.
[0061] In such embodiments, the height difference between the first surface 101 of the first battery piece 11 and the first surface 101 of the second battery piece 12 can be, for example, 90um, 95um, 100um, 105um, 110um, 115um, 120um, 125um, 130um, 135um, 140um, 145um, 150um or any value between 90um-150um. The height difference between the second surface 102 of the first battery piece 11 and the second surface 102 of the second battery piece 12 can be, for example, 90um, 95um, 100um, 105um, 110um, 115um, 120um, 125um, 130um, 135um, 140um, 145um, 150um or any value between 90um-150um.
[0062] As Figure 3 , Figure 5 , Figure 7 andFigure 9 As shown, in some preferred embodiments, the first surface 101 of the first cell piece 11 is flush with the first surface 101 of the second cell piece 12, and the second surface 102 of the first cell piece 11 is also flush with the second surface 102 of the second cell piece 12.
[0063] In this way, the height difference between the two adjacent back contact cell pieces 10 can be eliminated, and the product's crack and fragment rate can be reduced as much as possible, thereby improving the yield as much as possible.
[0064] In some embodiments, the length of the portion where the first protrusion 111 and the second protrusion 121 are stacked and fitted in the first direction is less than 2 mm.
[0065] In this way, setting the length of the stacked portion of the two adjacent back contact cell pieces 10 to be less than 2 mm can avoid the length of the stacked portion being too large, thereby causing the power generation area of a single back contact cell piece 10 to be too small. Meanwhile, when the first protrusion 111 and the second protrusion 121 only have a silicon wafer portion, setting the length to be less than 2 mm can avoid the area of the invalid region of the first cell piece 11 and the second cell piece 12 being too large.
[0066] Specifically, in such embodiments, the length of the portion where the first protrusion 111 and the second protrusion 121 are stacked and fitted in the first direction may, for example, be 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, or 2 mm. Preferably, it is less than or equal to 1 mm.
[0067] Please refer to Figure 3 and Figure 4 In some embodiments, the first protrusion 111 is a stepped protrusion, the second protrusion 121 is also a stepped protrusion, a first groove 13 is formed on the edge of the first surface 101 of the first cell piece 11 toward the side of the second cell piece 12 to form the first protrusion 111, a second groove 14 is formed on the edge of the second surface 102 of the second cell piece 12 toward the side of the first cell piece 11 to form the second protrusion 121, the first protrusion 111 is fitted into the second groove 14, and the second protrusion 121 is fitted into the first groove 13 to make the first protrusion 111 and the second protrusion 121 stacked and fitted with each other.
[0068] Thus, by forming the first groove 13 and the second groove 14 on the first surface 101 and the second surface 102 of the two adjacent back contact cells 10 respectively, the first protrusion 111 and the second protrusion 121 can be formed as stepped protrusions, so that the first protrusion 111 and the second protrusion 121 can be completely matched and spliced together, thereby reducing or even eliminating the height difference between the two adjacent back contact cells 10. Meanwhile, the first groove 13 and the second groove 14 can be formed by etching (e.g., laser etching), without the need to cut the back contact cell 10, thereby reducing the fragmentation rate.
[0069] Specifically, as shown in Figure 3 and Figure 4 , in such an embodiment, the first groove 13 penetrates through the side of the first cell 11 facing the second cell 12 to form a stepped first protrusion 111 at the edge of the first cell 11, and the second groove 14 penetrates through the side of the second cell 12 facing the first cell 11 to form a stepped second protrusion 121 at the edge of the second cell 12.
[0070] Further, as shown in Figure 3 and Figure 4 , in such an embodiment, when the first cell 11 has the second cell 12 on both sides, the first surface 101 of the first cell 11 has the first groove 13 and the first protrusion 111 formed on both side edges in the first direction, and when the second cell 12 has the first cell 11 on both sides, the second surface 102 of the second cell 12 has the second groove 14 and the second protrusion 121 formed on both side edges in the first direction.
[0071] Thus, in the manufacturing process, only one etching process is needed to form the two first protrusions 111 on the first surface 101 of the first cell 11 and the second surface 102 of the second cell 12, without the need to etch both surfaces of the first cell 11 and the second cell 12, thereby simplifying the manufacturing process.
[0072] Specifically, as shown in Figure 3 and Figure 4 , in such an embodiment, when the first cell 11 has the second cell 12 on both sides, the first surface 101 of the first cell 11 has the first groove 13 and the first protrusion 111 formed on both sides, and the first cell 11 is in an inverted convex letter shape (based on the drawings), and when the first cell 11 has the second cell 12 on both sides, the second surface 102 of the second cell 12 has the second groove 14 and the second protrusion 121 formed on both sides, and the back contact cell 10 is in a convex letter shape (based on the drawings), i.e., in the back contact cell string 100, the structures of the two adjacent back contact cells are different.
[0073] In some embodiments, the depth of the first groove 13 is 45um-80um and the depth of the second groove 14 is 45um-80um in the thickness direction of the back contact cell 10.
[0074] In this way, the depth of the first groove 13 and the second groove 14 can be prevented from being too deep to cause the thickness of the first protrusion 111 and the second protrusion 121 to be too thin to result in too low strength to cause the fragments in the conveying process.
[0075] Specifically, in such embodiments, the depth of the first groove 13 can be, for example, 45um, 50um, 55um, 60um, 65um, 70um, 75um, 80um or any value between 45um-80um. The depth of the second groove 14 can be, for example, 45um, 50um, 55um, 60um, 65um, 70um, 75um, 80um or any value between 45um-80um.
[0076] Further, in some embodiments, the sum of the depth of the first groove 13 and the second groove 14 is equal to the thickness of the back contact cell 10.
[0077] In this way, after the first protrusion 111 and the second protrusion 121 are spliced, the first surface 101 and the second surface 102 of the adjacent two back contact cells 10 can be flush, eliminating the height difference between the adjacent two back contact cells 10.
[0078] In some possible embodiments, the depth of the first groove 13 can be half of the thickness of the back contact cell 10, and the depth of the second groove 14 can also be half of the thickness of the back contact cell 10. In this way, after the first protrusion 111 and the second protrusion 121 are spliced, the sum of the height of the first protrusion 111 and the second protrusion 121 is equal to the thickness of the back contact cell 10, which can eliminate the height difference between the adjacent two back contact cells 10.
[0079] Please refer to Figure 5 and Figure 6 In other embodiments, the first protrusion 111 is a stepped protrusion, and the second protrusion 121 is also a stepped protrusion. When the first cell 11 has two second cells 12 on both sides, the first surface 101 of the first cell 11 forms a third groove 15 towards the edge of one side of one of the second cells 12 to form a first protrusion 111, and the second surface 102 of the first cell 11 forms a fourth groove 16 towards the surface of one side of the other second cell 12 to form another first protrusion 111.
[0080] When the first cell tab 11 is arranged on both sides of the second cell tab 12, the first surface 101 of the second cell tab 12 is formed with a fifth groove 17 towards the edge of one side of one of the first cell tabs 11 to form a second protrusion 121, and the second surface 102 of the second cell tab 12 is formed with a sixth groove 18 towards the surface of one side of the other first cell tab 11 to form another second protrusion 121.
[0081] In this way, by forming the third groove 15 and the fourth groove 16 on the two surfaces of the first cell tab 11 respectively, two different first protrusions 111 can be formed, and by forming the fifth groove 17 and the sixth groove 18 on the two surfaces of the second cell tab 12, two different second protrusions 121 can be formed, and the first protrusions 111 and the second protrusions 121 can also achieve stacking and fitting.
[0082] Specifically, as shown in Figure 5 and Figure 6 In such embodiments, the structures of all the back contact cell tabs 10 are the same, all in Z shape, except for the back contact cell tabs 10 located at the two ends of the back contact cell string 100. Of course, in some embodiments, the structures of all the back contact cell tabs 10 can also be the same, which is not limited here.
[0083] In addition, as shown in Figure 5 and Figure 6 In such embodiments, the third groove 15 and the fourth groove 16 respectively penetrate the first cell tab 11 towards the sides of two different second cell tabs 12 to form stepped first protrusions 111 at the two edges of the first cell tab 11 respectively, and the fifth groove 17 and the sixth groove 18 respectively penetrate the second cell tab 12 towards the sides of two different first cell tabs 11 to form stepped second protrusions 121 at the two edges of the second cell tab 12 respectively.
[0084] In some embodiments, in the thickness direction of the back contact cell tab 10, the depths of the third groove 15, the fourth groove 16, the fifth groove 17 and the sixth groove 18 can all be 45um-80um.
[0085] In this way, it can be avoided that the depths of the third groove 15, the fourth groove 16, the fifth groove 17 and the sixth groove 18 are too deep, causing the thicknesses of the first protrusions 111 and the second protrusions 121 to be too thin, resulting in too low strength and causing fragments during transportation.
[0086] Specifically, in such embodiments, the depths of the third groove 15, the fourth groove 16, the fifth groove 17 and the sixth groove 18 can be, for example, 45um, 50um, 55um, 60um, 65um, 70um, 75um, 80um or any value between 45um-80um.
[0087] In some embodiments, the depth of one of the third groove 15 and the fourth groove 16 and the depth of one of the fifth groove 17 and the sixth groove 18 are equal to the thickness of the back contact cell 10.
[0088] Thus, after the first protrusion 111 and the second protrusion 121 are spliced, the first surface 101 and the second surface 102 of the two adjacent back contact cells 10 can be flush, and the height difference between the two adjacent back contact cells 10 can be eliminated.
[0089] In some possible embodiments, the depth of the third groove 15, the fourth groove 16, the fifth groove 17 and the sixth groove 18 can be half of the thickness of the back contact cell 10. In this way, after the first protrusion 111 and the second protrusion 121 are spliced, the height of the first protrusion 111 and the second protrusion 121 is equal to the thickness of the back contact cell 10, and the height difference between the two adjacent back contact cells 10 can be eliminated.
[0090] Please refer to Figures 7-10 In some embodiments, the first cell 11 can include a first side surface 19 facing the second cell 12, and the first side surface 19 is a bevel surface to form the first protrusion 111 on the first cell 11. The second cell 12 includes a second side surface 120 facing the first cell 11, and the second side surface 120 is also a bevel surface to form the second protrusion 121 on the second cell 12. The second side surface 120 cooperates with the first side surface 19 to make the first protrusion 111 and the second protrusion 121 stack and fit with each other.
[0091] Thus, by cooperating the two bevel protrusions, the height difference between the two adjacent back contact cells 10 can be reduced or even eliminated, thereby reducing the fragment rate and improving the yield.
[0092] Specifically, as Figures 7-10 shown, in such embodiments, the projection of the first side surface 19 and the second side surface 120 in the thickness direction corresponds to the first protrusion 111 and the second protrusion 121, respectively. The "second side surface 120 cooperates with the first side surface 19" means that the second side surface 120 coincides with the first side surface 19.
[0093] Further, as Figures 7-10As shown in the examples shown in Figs. 1 and 2, when the first cell sheet 11 has the second cell sheet 12 on both sides, the first side surface 19 of the first cell sheet 11 toward the first surface 101 forms an acute angle, and the first side surface 19 of the first cell sheet 11 toward the second cell sheet 12 forms an obtuse angle. In this case, the first side surface 19 of the first cell sheet 11 and the second side surface 120 of the second cell sheet 12 are parallel, and the first cell sheet 11 has a trapezoidal shape, and the second cell sheet 12 has a rectangular shape.
[0094] As shown in Figs. 1 and 2, when the first cell sheet 11 has the second cell sheet 12 on both sides, the first side surface 19 of the first cell sheet 11 toward the first surface 101 forms an acute angle, and the first side surface 19 of the first cell sheet 11 toward the second cell sheet 12 forms an obtuse angle. In this case, the first side surface 19 of the first cell sheet 11 and the second side surface 120 of the second cell sheet 12 are parallel, and the first cell sheet 11 has a trapezoidal shape, and the second cell sheet 12 has a rectangular shape. Figure 7 Figure 8 As shown in Figs. 1 and 2, when the first cell sheet 11 has the second cell sheet 12 on both sides, the first side surface 19 of the first cell sheet 11 toward the first surface 101 forms an acute angle, and the first side surface 19 of the first cell sheet 11 toward the second cell sheet 12 forms an obtuse angle. In this case, the first side surface 19 of the first cell sheet 11 and the second side surface 120 of the second cell sheet 12 are parallel, and the first cell sheet 11 has a trapezoidal shape, and the second cell sheet 12 has a rectangular shape. Figure 7 Figure 8 As shown in Figs. 1 and 2, when the first cell sheet 11 has the second cell sheet 12 on both sides, the first side surface 19 of the first cell sheet 11 toward the first surface 101 forms an acute angle, and the first side surface 19 of the first cell sheet 11 toward the second cell sheet 12 forms an obtuse angle. In this case, the first side surface 19 of the first cell sheet 11 and the second side surface 120 of the second cell sheet 12 are parallel, and the first cell sheet 11 has a trapezoidal shape, and the second cell sheet 12 has a rectangular shape.
[0095] As shown in Figs. 1 and 2, when the first cell sheet 11 has the second cell sheet 12 on both sides, the first side surface 19 of the first cell sheet 11 toward the first surface 101 forms an acute angle, and the first side surface 19 of the first cell sheet 11 toward the second cell sheet 12 forms an obtuse angle. In this case, the first side surface 19 of the first cell sheet 11 and the second side surface 120 of the second cell sheet 12 are parallel, and the first cell sheet 11 has a trapezoidal shape, and the second cell sheet 12 has a rectangular shape. Figure 9 Figure 10 As shown in Figs. 1 and 2, when the first cell sheet 11 has the second cell sheet 12 on both sides, the first side surface 19 of the first cell sheet 11 toward the first surface 101 forms an acute angle, and the first side surface 19 of the first cell sheet 11 toward the second cell sheet 12 forms an obtuse angle. In this case, the first side surface 19 of the first cell sheet 11 and the second side surface 120 of the second cell sheet 12 are parallel, and the first cell sheet 11 has a trapezoidal shape, and the second cell sheet 12 has a rectangular shape. Figure 9 Figure 10 As shown in Figs. 1 and 2, when the first cell sheet 11 has the second cell sheet 12 on both sides, the first side surface 19 of the first cell sheet 11 toward the first surface 101 forms an acute angle, and the first side surface 19 of the first cell sheet 11 toward the second cell sheet 12 forms an obtuse angle. In this case, the first side surface 19 of the first cell sheet 11 and the second side surface 120 of the second cell sheet 12 are parallel, and the first cell sheet 11 has a trapezoidal shape, and the second cell sheet 12 has a rectangular shape.
[0096] In the description of the specification, reference to "some embodiments", "certain embodiments", "exemplary embodiments", "specific embodiments", or "some examples" etc., indicate that the described features, structures, materials, or characteristics are included in at least one embodiment or example of the application. The several instances of
[0097] Moreover, the above-description does not include all of the information relevant to the application, which will become apparent to those skilled in the art after reading the description and claims.
Claims
1. A back contact cell string, characterized in that, The back contact cell string comprises a plurality of back contact cells, each of which has opposite first and second surfaces, and the first surfaces of all the back contact cells are oriented in the same direction; The first and second cells are arranged alternately in the first direction and are connected in series, the first cell has a first protrusion formed on the edge of the side of the first cell facing the second cell, and the second cell has a second protrusion formed on the edge of the side of the second cell facing the first cell, the second protrusion and the first protrusion are stacked and fitted to make the height difference between the first surface of the first cell and the first surface of the second cell less than the thickness of the back contact cell.
2. The back contact cell string of claim 1, wherein, The first and second protrusions only have a silicon wafer part and do not have metal electrodes on the first and second protrusions.
3. The back contact cell string of claim 1, wherein, The first surface of the first cell is flush with the first surface of the second cell, and the second surface of the first cell is also flush with the second surface of the second cell.
4. The back contact cell string of claim 1, wherein, The height difference between the first surface of the first cell and the first surface of the second cell is 90-150 microns, and the height difference between the second surface of the first cell and the second surface of the second cell is 90-150 microns.
5. The back contact cell string of claim 1, wherein, The length of the part where the first and second protrusions are stacked and fitted in the first direction is less than 2 mm.
6. The back contact cell string of claim 1, wherein, The first protrusion is a stepped protrusion, and the second protrusion is also a stepped protrusion. The first surface of the first cell has a first groove formed on the edge of the side of the first cell facing the second cell to form the first protrusion, and the second surface of the second cell has a second groove formed on the edge of the side of the second cell facing the first cell to form the second protrusion, the first protrusion is fitted in the second groove, and the second protrusion is fitted in the first groove to make the first and second protrusions stacked and fitted with each other.
7. The back contact cell string of claim 6, wherein, When the first cell has the second cell on both sides, the first surface of the first cell has the first groove and the first protrusion formed on the edges of the two sides in the first direction, and when the second cell has the first cell on both sides, the second surface of the second cell has the second groove and the second protrusion formed on the edges of the two sides in the first direction.
8. The back contact cell string of claim 6, wherein, In the thickness direction of the back contact cell, the depth of the first and second grooves is 45-80 microns.
9. The back contact cell string of claim 6, wherein, The sum of the depths of the first and second grooves is equal to the thickness of the back contact cell.
10. The back contact cell string of claim 1, wherein, The first protrusion is a stepped protrusion, and the second protrusion is also a stepped protrusion. When the first cell has the second cell on both sides, a third groove is formed on the edge of the first surface of the first cell towards one side of the second cell to form one first protrusion, and a fourth groove is formed on the surface of the second surface of the first cell towards the other side of the second cell to form another first protrusion; When the second cell has the first cell on both sides, a fifth groove is formed on the edge of the first surface of the second cell towards one side of the first cell to form one second protrusion, and a sixth groove is formed on the surface of the second surface of the second cell towards the other side of the first cell to form another second protrusion.
11. The back contact cell string of claim 10, wherein, In the thickness direction of the back contact cell, the depth of the third groove, the fourth groove, the fifth groove and the sixth groove is 45um-80um.
12. The back contact cell string of claim 10, wherein, In the thickness direction of the back contact cell, the sum of the depth of one of the third groove and the fourth groove and the depth of one of the fifth groove and the sixth groove is equal to the thickness of the back contact cell.
13. The back contact cell string of claim 1, wherein, The first cell includes a first side surface towards the second cell, the first side surface is an inclined surface to form the first protrusion on the first cell, the second cell includes a second side surface towards the first cell, the second side surface is also an inclined surface to form the second protrusion on the second cell, and the second side surface cooperates with the first side surface to make the first protrusion and the second protrusion stack and fit with each other.
14. The back contact cell string of claim 13, wherein, One of the first side surface and the second side surface forms an acute angle with the first surface, and the other forms an obtuse angle with the first surface, and the sum of the angle between the first side surface and the first surface and the angle between the second side surface and the first surface is 180°.
15. A battery assembly characterized by, The back contact cell string includes a plurality of back contact cells according to any one of claims 1-14.
16. A photovoltaic system characterized by, The battery assembly includes the battery assembly according to claim 15.