Back contact solar cell, cell string, cell module and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a back contact solar cell sheet, a cell string, a cell assembly and a photovoltaic system. A first main grid and a second main grid of the electrode structure are arranged at the two ends of a first auxiliary grid and a second auxiliary grid respectively in the first direction, the first main grid is connected with all the first auxiliary grids, and the second main grid is connected with all the second auxiliary grids. Therefore, when the slice battery needs to be manufactured, cutting can be carried out in the interval between every two adjacent electrode structures in the direction parallel to the first main grid and the second main grid, meanwhile, the electrode structures on the backlight face are independently arranged at intervals, the length of the auxiliary grid in each electrode structure is short, the transmission distance of the slice battery is short, series resistance is small, and efficiency can be improved. After the slice battery is formed, only the first main grid and the second main grid are arranged at the two ends of the first direction, and only the two main grids need to be welded, so that the battery string can be welded simply.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cells, in particular to a back-contact solar cell sheet, a battery string, a battery assembly and a photovoltaic system. Background Art

[0002] With the development of photovoltaic technology, solar cells have become the core of photovoltaic power generation. At present, in solar cells, since the back-contact solar cell places the emitter and base contact electrodes on the back side of the cell (non-light-receiving side), the light-receiving side of the cell is not blocked by any metal electrode, which can effectively increase the short-circuit current of the cell and thus improve the conversion efficiency. Therefore, in order to improve the conversion efficiency of the cell, back-contact solar cells have become the main research direction.

[0003] The electrode structure on the back side of a back-contact solar cell is usually composed of several sub-grids and several main grids, and the sub-grids and the main grids are arranged crosswise. In the related art, the length of the sub-grid of the electrode structure of the back-contact solar cell is long, the transmission distance is long, the series resistance is large, and there are many main grids corresponding to the same sub-grid. The welding process is more complicated. At the same time, it is impossible to slice in the direction parallel to the main grid during slicing. Utility Model Content

[0004] The utility model provides a back-contact solar cell, a cell string, a cell assembly and a photovoltaic system, aiming to solve the technical problems in the prior art of large series resistance of back-contact solar cells, complex welding process and inability to slice along a direction parallel to the main grid.

[0005] The utility model is implemented as follows: the back contact solar cell of the embodiment of the utility model comprises a silicon wafer and at least three electrode structures arranged on the backlight surface of the silicon wafer, at least three electrode structures are arranged at intervals along the first direction of the silicon wafer, and the electrode structures comprise:

[0006] A plurality of first sub-grids and a plurality of second sub-grids, wherein the plurality of first sub-grids and the plurality of second sub-grids are alternately arranged in sequence and spaced apart along a second direction of the silicon wafer, and the second direction intersects the first direction; and

[0007] A first main grid and a second main grid, wherein the first main grid and the second main grid are spaced apart along the first direction, the first main grid is located on one side of the first sub-grid and the second sub-grid and is connected to all ends of the first sub-grid, and the second sub-grid is located on the other side of the first sub-grid and the second sub-grid and is connected to all ends of the second sub-grid.

[0008] Furthermore, in at least three of the electrode structures, the first main grid in at least one of the electrode structures is adjacent to the second main grid in another of the electrode structures.

[0009] Furthermore, in at least three of the electrode structures, the first main grid in at least one of the electrode structures is adjacent to the first main grid in another of the electrode structures.

[0010] Furthermore, when the first main gates of two adjacent electrode structures are adjacent to each other, a doping layer having the same polarity as that of the silicon wafer is provided in a spacing region between the two adjacent first main gates.

[0011] Furthermore, the distance between two adjacent electrode structures is 0.6 mm-1.6 mm.

[0012] Furthermore, in the first direction, the distance between two adjacent electrode structures is twice the distance between the edgemost electrode structure and the edge of the silicon wafer.

[0013] Furthermore, the cross-sectional area of ​​the first main grid and the second main grid is 1000um. 2 -50000um 2 .

[0014] The present application also provides a battery string, the battery string comprising a plurality of sliced ​​batteries and connectors, the sliced ​​batteries being obtained by cutting and / or splitting the back contact solar cell described in any one of the above along the interval between two adjacent electrode structures, and each sliced ​​battery comprising at least one electrode structure;

[0015] Among the two adjacent sliced ​​batteries, the connecting member connects the first main grid of one of the sliced ​​batteries and the second main grid of the other sliced ​​battery.

[0016] The present application also provides another battery string, which includes several of the above-mentioned back-contact solar cells. In each back-contact solar cell, the first main grid of one of the adjacent electrode structures is adjacent to the second main grid of another adjacent electrode structure, the first main grid and the second main grid are connected by a conductive member, and two adjacent back-contact solar cells are connected by a welding strip.

[0017] Furthermore, the conductive member includes at least one of conductive glue, solder paste or solder tape.

[0018] Furthermore, there are a plurality of the conductive members, and the plurality of the conductive members are arranged at intervals along the second direction, and an interval between two adjacent conductive members is less than or equal to 30 mm.

[0019] Furthermore, the width of the conductive member is 0.5 mm-2 mm.

[0020] The present application also provides a battery assembly, which includes a plurality of the above-mentioned battery strings.

[0021] The present application also provides a photovoltaic system, which includes the above-mentioned battery assembly.

[0022] In the back-contact solar cell, cell string, cell assembly and photovoltaic system of the embodiment of the present application, at least three electrode structures are arranged at intervals on the backlight surface of the silicon wafer, and the first main grid and the second main grid of the electrode structure are respectively arranged at the two ends of the first sub-grid and the second sub-grid along the first direction, the first main grid connects all the first sub-grids, and the second main grid connects all the second sub-grids. In this way, on the one hand, when it is necessary to make a sliced ​​battery, the back-contact solar cell can be cut along the direction parallel to the first main grid and the second main grid at the interval between two adjacent electrode structures, so as to obtain at least three sliced ​​batteries (i.e., three slices), and at the same time, in the entire back-contact solar cell, the electrode structures on the backlight surface are arranged separately at intervals, the length of the sub-grid in a single electrode structure is shorter, the transmission distance of the sliced ​​battery is short, the series resistance is small, and the efficiency can be improved. On the other hand, after the sliced ​​battery is formed, only the two ends in the first direction have the first main grid and the second main grid, and only two main grids need to be welded, which is relatively simple when welding into a battery string.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a module schematic diagram of a photovoltaic system provided in an embodiment of the present application;

[0025] Figure 2 is a module schematic diagram of a battery assembly provided in an embodiment of the present application;

[0026] Figure 3 is a schematic diagram of the planar structure of a back-contact solar cell provided in an embodiment of the present application;

[0027] Figure 4 is a schematic diagram of the structure of a battery string provided in an embodiment of the present application;

[0028] Figure 5 is a schematic diagram of the structure of a silicon wafer provided in an embodiment of the present application;

[0029] Figure 6 is a cross-sectional schematic diagram of a back-contact solar cell provided in an embodiment of the present application;

[0030] Figure 7 is another cross-sectional schematic diagram of a back-contact solar cell provided in an embodiment of the present application;

[0031] Figure 8 is another cross-sectional schematic diagram of a back-contact solar cell provided in an embodiment of the present application;

[0032] Fig. 9 is another schematic diagram of the structure of a back-contact solar cell provided in an embodiment of the present application.

[0033] Description of main component symbols:

[0034] Photovoltaic system 1000;

[0035] Battery assembly 200, battery string 210, connector 220;

[0036] Back contact solar cell 100, sliced ​​cell 101, silicon wafer 10, light-facing surface 11, backlight surface 12, electrode structure 20, first auxiliary grid 21, first auxiliary grid pre-plating layer 211, first auxiliary grid electroplating layer 212, second auxiliary grid 22, second auxiliary grid pre-plating layer 221, second auxiliary grid electroplating layer 222, first main grid 23, first main grid pre-plating layer 231, first main grid electroplating layer 232, second main grid 24, second main grid pre-plating layer 241, second main grid electroplating layer 242, first doping layer 30, second doping layer 40, passivation film layer 50, conductive member 60. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the utility model, and cannot be understood as limiting the utility model. In addition, it should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model.

[0038] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "top", "bottom", "lateral", "longitudinal", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0041] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0042] The disclosure below provides many different embodiments or examples for realizing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the utility model. In addition, the utility model may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the utility model provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0043] In the utility model, the setting of the first temperature sensor can monitor the temperature of the battery cell to be tested entering the PL testing system, and can feed back its temperature data to the control and analysis module. The control and analysis module can determine the difference between the temperature of the battery cell to be tested and the target temperature based on the temperature data of the battery cell to be tested, and then correct the grayscale value image of the battery cell to be tested based on this temperature difference, thereby eliminating the temperature interference of the battery cell to be tested and improving the accuracy of detection.

[0044] Embodiment 1

[0045] See also Figure 1-Figure 4 The photovoltaic system 1000 in the embodiment of the present application may include the battery assembly 200 in the embodiment of the present application, and the battery assembly 200 in the embodiment of the present application may include several battery strings 210 in the embodiment of the present application.

[0046] In some embodiments, the battery string 210 may include several sliced ​​batteries 101 (only three sliced ​​batteries 101 are used as an example in the figure) and connectors 220. The sliced ​​batteries 101 can be obtained by cutting and / or splitting the back contact solar cell 100 in the embodiment of the present application.

[0047] In the present application, multiple sliced ​​batteries 101 in the battery assembly 200 can be connected in series in sequence through a connector 220 to form a battery string 210. The connector 220 can be a conductive element such as a welding strip, a bus bar, a metal clip, etc., and no specific limitation is made here.

[0048] The battery strings 210 in the battery assembly 200 can be connected in series, in parallel, or in a combination of series and parallel to achieve current bus output. For example, the battery strings 210 can be connected through a bus bar.

[0049] See also Figure 3 as well as Figure 6 The back-contact solar cell 100 in the embodiment of the present application may include a silicon wafer 10 and at least three electrode structures 20. The silicon wafer 10 has a relative light-facing surface 11 and a backlight surface 12. The silicon wafer 10 may be a P-type silicon wafer or an N-type silicon wafer, and no specific limitation is made here.

[0050] like Figure 3 As shown, at least three electrode structures 20 may be spaced apart along the first direction of the silicon wafer 10, and the electrode structure 20 may include a plurality of first sub-gates 21, a plurality of second sub-gates 22, a first main gate 23, and a second main gate 24. The plurality of first sub-gates 21 and the plurality of second sub-gates 22 are alternately arranged and spaced apart in sequence along the second direction of the silicon wafer 10, and the second direction intersects with the first direction.

[0051] The first main gate 23 and the second main gate 24 are arranged at intervals along the first direction. The first main gate 23 is located on one side of the first sub-gate 21 and the second sub-gate 22 and is connected to the ends of all the first sub-gates 21. The second sub-gate 22 is located on the other side of the first sub-gate 21 and the second sub-gate 22 and is connected to the ends of all the second sub-gates 22. The polarities of the first main gate 23 and the second main gate 24 are opposite, and the polarities of the first sub-gate 21 and the second sub-gate 22 are opposite.

[0052] The sliced ​​cells 101 can be obtained by cutting and / or splitting the back contact solar cell 100 along the interval between two adjacent electrode structures 20 , and each sliced ​​cell 101 includes at least one electrode structure 20 .

[0053] In the back-contact solar cell 100, the cell string 210, the cell assembly 200 and the photovoltaic system 1000 of the embodiment of the present application, at least three electrode structures 20 are arranged at intervals on the backlight surface 12 of the silicon wafer 10, and the first main grid 23 and the second main grid 24 of the electrode structure 20 are respectively arranged at the two ends of the first sub-grid 21 and the second sub-grid 22 along the first direction, the first main grid 23 connects all the first sub-grids 21, and the second main grid 24 connects all the second sub-grids 22. In this way, on the one hand, when it is necessary to make a sliced ​​cell 101, the back-contact solar cell 100 can be cut along the direction parallel to the first main grid 23 and the second main grid 24 at the interval between two adjacent electrode structures 20, so as to obtain at least three sliced ​​cells 101 (i.e., three slices), and at the same time, in the entire back-contact solar cell 100, the electrode structures 20 on the backlight surface 12 are arranged separately at intervals, the length of the sub-grid in a single electrode structure 20 is short, the transmission distance of the sliced ​​cell 101 is short, the series resistance is small, and the efficiency can be improved. On the other hand, after the sliced ​​battery 101 is formed, only the two ends in the first direction have the first main grid 23 and the second main grid 24 , and only the two main grids need to be welded, which makes it easier to weld the battery string 210 .

[0054] Specifically, in the present application, the first direction may be the lateral direction of the back contact solar cell 100, and the second direction may be the longitudinal direction of the back contact solar cell, the two may intersect vertically, the first auxiliary grid 21 and the second auxiliary grid 22 may be alternately arranged in parallel along the longitudinal direction and the first auxiliary grid 21 and the second auxiliary grid 22 may extend along the lateral direction, and the first main grid 23 and the second main grid 24 may be arranged at both ends of the first auxiliary grid 21 and the second auxiliary grid 22 along the lateral direction and extend along the longitudinal direction. When making the sliced ​​battery 101, cutting and / or splitting may be performed along the interval between two adjacent electrode structures 20 in the longitudinal direction to form a plurality of sliced ​​batteries 101.

[0055] See also Figure 6In the embodiment of the present application, a first doping layer 30 and a second doping layer 40 are arranged alternately in sequence along a second direction on the backlight surface 12 of the silicon wafer 10, one of the first doping layer 30 and the second doping layer 40 is a P-type doping layer, and the other is an N-type doping layer. The backlight surface 12 is covered with a passivation film layer 50, and the first sub-gate 21 can be arranged on the first doping layer 30 and penetrate the passivation film layer 50 to contact the first doping layer 30, and the second sub-gate 22 can be arranged on the second doping layer 40 and penetrate the passivation film layer 50 to contact the second doping layer 40.

[0056] like Figure 4 As shown, in the present application, when using sliced ​​batteries 101 to make a battery string 210, each sliced ​​battery 101 can be arranged along the first direction, and the first main grid 23 and the second main grid 24 of two adjacent sliced ​​batteries 101 are adjacent, and then the first main grid 23 and the second main grid 24 are conductively connected by the connector 220. For example, when the connector 220 is a welding strip and a bus bar, the connector 220 can be placed between two adjacent sliced ​​batteries 101, and then the connector 220 is welded to the first main grid 23 and the second main grid 24. Of course, in order to avoid reliability problems during welding, the connector 220 can also be a clamping member, so that the connector 220 can be clamped on the adjacent first main grid 23 and the second main grid 24 to achieve connection, thereby forming a battery string 210.

[0057] It is understood that in the embodiment of the present application, the battery assembly 200 may also include a metal frame, a back plate, a photovoltaic glass and an adhesive film (not shown in the figure). The adhesive film may be filled between the front and photovoltaic glass, the back and the back plate of the back contact solar cell 100, and the adjacent cells, etc. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film may be an EVA adhesive film or a POE adhesive film, which may be selected according to actual conditions and is not limited here.

[0058] Photovoltaic glass can cover the adhesive film on the front side of the back contact solar cell 100. The photovoltaic glass can be ultra-white glass, which has high light transmittance, high transparency, and excellent physical, mechanical and optical properties. For example, the light transmittance of ultra-white glass can reach more than 90%, and it can protect the back contact solar cell 100 without affecting the efficiency of the back contact solar cell 100 as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the back contact solar cell 100 together, and the presence of the adhesive film can seal and insulate the back contact solar cell 100 and prevent water and moisture.

[0059] The back sheet can be attached to the adhesive film on the back of the back contact solar cell 100. The back sheet can protect and support the back contact solar cell 100, and has reliable insulation, water resistance and aging resistance. There are multiple options for the back sheet, which can usually be tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc., which can be set according to specific circumstances and are not limited here. The whole composed of the back sheet, the back contact solar cell 100, the adhesive film and the photovoltaic glass can be set on a metal frame. The metal frame serves as the main external support structure of the entire battery assembly 200, and can stably support and install the battery assembly 200. For example, the battery assembly 200 can be installed at the required installation position through the metal frame.

[0060] Furthermore, in this embodiment, the photovoltaic system 1000 can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system 1000 are not limited to this, that is, the photovoltaic system 1000 can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system 1000 may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple battery assemblies 200. For example, multiple battery assemblies 200 may form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0061] Embodiment 2

[0062] See also Figure 3 In some embodiments, among the at least three electrode structures 20 , a first main gate 23 in at least one electrode structure 20 is adjacent to a second main gate 24 in another electrode structure 20 .

[0063] In this way, after cutting and / or splitting to form sliced ​​batteries 101, when making the battery string 210, the two sliced ​​batteries 101 with adjacent first main grid 23 and second main grid 24 do not need to be rotated 180° to make the first main grid 23 and second main grid 24 of the two sliced ​​batteries 101 adjacent to each other, which can save manufacturing steps and improve manufacturing efficiency.

[0064] Specifically, in such an embodiment, among the at least three electrode structures 20, the number of electrode structures 20 adjacent to the first main grid 23 and the second main grid 24 may be two, three or even more. Figure 3As shown, taking three electrode structures 20 as an example, from left to right, the first main grid 23 of the first electrode structure 20 is adjacent to the second main grid 24 of the second electrode structure 20, and the first main grid 23 of the second electrode structure 20 can be adjacent to the second main grid 24 of the third electrode structure 20. Of course, the first main grid 23 of the second electrode structure 20 can also be adjacent to the first main grid 23 of the third electrode structure 20, and there is no specific limitation here.

[0065] Of course, it is understood that in some embodiments, among the at least three electrode structures 20, there may be at least one electrode structure 20 in which the first main grid 23 is adjacent to the first main grid 23 in another electrode structure 20, and the specific details are not limited here. It is not difficult to understand that in such a case, after the sliced ​​battery 101 is manufactured, one of the two sliced ​​batteries 101 with adjacent first main grids 23 can be rotated 180° and then connected to the second main grid 24 of the other sliced ​​battery 101 through the connector 220.

[0066] Embodiment 3

[0067] In some embodiments, when the first main gates 23 of two adjacent electrode structures 20 are adjacent to each other, a doping layer having the same polarity as that of the silicon wafer 10 is disposed in a spacing region between the two adjacent first main gates 23 .

[0068] In this way, a doping layer having the same polarity as the silicon wafer 10 is arranged between the two first main gates 23 , so that the subsequent cutting loss can be reduced.

[0069] Specifically, in such an embodiment, when the silicon wafer 10 is a P-type silicon wafer, the doping layer is a P-type doping layer, and when the silicon wafer 10 is an N-type silicon wafer, the doping layer is an N-type doping layer. During the cutting process, since the doping layer has the same polarity as the silicon wafer 10, the cutting loss can be reduced during the cutting process.

[0070] It can be understood that the doping layer is extended along the second direction, and it can preferably be an integrated structure with the first doping layer 30 or the second doping layer 40 mentioned above. For example, when the doping layer is a P-type doping layer and the first doping layer 30 is also a P-type doping layer, the two can be formed as one piece; when the doping layer is an N-type doping layer and the first doping layer 30 is also an N-type doping layer, the two can be formed as one piece.

[0071] Embodiment 4

[0072] In some embodiments, the spacing between two adjacent electrode structures 20 (ie, the spacing distance in the first direction) may be 0.6 mm-1.6 mm.

[0073] In this way, setting the distance between two adjacent electrode structures 20 within this reasonable range can facilitate subsequent cutting and / or splitting, avoid damaging the electrode structure 20 during cutting and splitting due to a small distance, and avoid excessively large ineffective area of ​​the back contact solar cell 100 due to a large distance.

[0074] Specifically, in such an embodiment, the spacing between two adjacent electrode structures 20 may be, for example, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm or any value between 0.6 mm and 1.6 mm, and is not limited here.

[0075] In some embodiments, in the first direction, the distance between two adjacent electrode structures 20 is twice the distance between the edgemost electrode structure 20 and the edge of the silicon wafer 10 .

[0076] In this way, when cutting into sliced ​​batteries, the cutting can be performed at the middle position of the spacing between the electrode structures 20, so that the blank area at the edge of each sliced ​​battery can be basically consistent, and the size of each sliced ​​battery can also be basically consistent.

[0077] Embodiment 5

[0078] See also Figure 5 In some embodiments, there is a cutting line (not shown) or a split groove 13 between two adjacent electrode structures 20 .

[0079] Thus, by forming a cutting line or a splitting groove 13 between two electrode structures 20 , subsequent cutting and / or splitting processes may be facilitated.

[0080] Embodiment 6

[0081] For further information, see Figure 5 In some embodiments, a split groove 13 is provided between two adjacent electrode structures 20 , and a width L of the split groove 13 is 0.1 mm-5 mm.

[0082] Thus, setting the width L of the split groove 13 within this reasonable range can ensure that the electrode area will not be cut during subsequent cutting, thereby ensuring the cutting accuracy. At the same time, it can also avoid the split groove 13 being too wide, which would lead to an excessively large ineffective area of ​​the back contact solar cell 100.

[0083] Specifically, in such an embodiment, the width of the split groove 13 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 2mm, 3mm, 4mm, 5mm or any value in the range of 0.1-5mm, and is not limited here.

[0084] Embodiment 7

[0085] See also Figure 5 In some embodiments, the depth H of the split groove 13 is less than or equal to one third of the thickness of the silicon wafer 10 .

[0086] In this way, setting the depth H of the crack groove 13 to be less than or equal to one third of the thickness of the silicon wafer 10 can provide a breaking point while avoiding the depth of the crack groove 13 being too deep, thereby ensuring the strength of the silicon wafer 10 at the crack groove 13 and reducing the risk of cracking during the manufacturing process of the back-contact solar cell 100. In other words, if the depth of the crack groove 13 is too deep, it will cause the crack groove 13 to be thinner, resulting in the back-contact solar cell 100 having too low strength at the crack groove 13, which is easy to cause cracking.

[0087] Specifically, for example, if the thickness of the silicon wafer 10 is 300 um, the depth of the split groove 13 can be 100 um, 90 um, etc., which can be set according to actual conditions.

[0088] In some embodiments, when making sliced ​​cells 101, pre-cutting can be performed at the splitting groove 13 by laser, and then the splitting can be achieved by a mechanical splitting process to separate the back contact solar cell 100 into multiple sliced ​​cells 101, that is, the splitting groove 13 is used for cutting and splitting.

[0089] Of course, it is understandable that in some embodiments, when forming the sliced ​​cells 101 , the back contact solar cell 100 may be directly cut into two sliced ​​cells 101 along the split groove 13 by cutting only, without using a splitting process.

[0090] Furthermore, in a possible embodiment, when the depth of the split groove 13 is sufficient and the conditions for direct splitting are met, the laser cutting process may not be used, but the splitting may be performed directly through the split groove 13 by mechanical splitting. In this way, there is no need to use laser cutting, thus avoiding damage caused by laser cutting.

[0091] In some embodiments, the crack groove 13 on the silicon wafer 10 can be formed before the first doping layer 30 and the second doping layer 40 are formed. That is, the crack groove 13 can be first formed on the silicon wafer 10 by laser, etching and other processes, and then the crack groove 13 can be blocked by a mask and the first doping layer 30 and the second doping layer 40 can be formed on the silicon wafer 10 by deposition and other methods. In this way, the crack groove 13 can be formed before the doping layer is formed, and there are no P-type and N-type doping regions at the crack groove 13. When laser cutting is performed later, cutting can be performed at the crack groove 13 without cutting into the doped area, thereby avoiding laser cutting into the doped area to increase recombination and reduce conversion efficiency.

[0092] Embodiment 8

[0093] See also Figure 6 , Figure 6 for Figure 3 In the cross-sectional view along the second direction at the positions of the first auxiliary grid 21 and the second auxiliary grid 22, in some embodiments, the first auxiliary grid 21 may include the first auxiliary grid 21 including a first auxiliary grid pre-plating layer 211 and a first auxiliary grid electroplating layer 212 plated on the first auxiliary grid pre-plating layer 211, the second auxiliary grid 22 includes a second auxiliary grid pre-plating layer 221 and a second auxiliary grid electroplating layer 222 plated on the second auxiliary grid pre-plating layer 221; the first main grid 23 contacts the first auxiliary grid pre-plating layer 211, and the second main grid 24 contacts the second auxiliary grid pre-plating layer 221.

[0094] In this way, by making the first sub-grid 21 and the second sub-grid 22 both include a pre-plating layer and an electroplating layer, the seed layer can be thickened and widened by electroplating, thereby improving the conductivity of the first sub-grid 21 and the second sub-grid 22. At the same time, traditional sub-grids generally use silver paste, and forming the sub-grid by electroplating can reduce the use of silver paste.

[0095] Specifically, in the embodiment of the present application, the first auxiliary gate pre-plating layer 211 forms an ohmic contact with the first doping layer 30 on the silicon wafer 10, and the second auxiliary gate pre-plating layer 221 forms an ohmic contact with the second doping layer 40 on the silicon wafer 10. Both the first auxiliary gate electroplating layer 212 and the second auxiliary gate electroplating layer 222 can be electroplated copper layers.

[0096] In some embodiments, the first sub-gate pre-plating layer 211 and the second sub-gate pre-plating layer 221 may include a seed layer, which may be prepared by a physical vapor deposition method, so that a stable ohmic contact may be formed with the first doping layer 30 and the second doping layer 40 through the seed layer.

[0097] Specifically, the seed layer may be a metal material, which may be preferably an alloy material. In some embodiments, the main component of the seed layer may include copper or aluminum or nickel.

[0098] In some embodiments, the seed layer may include a main component and a strengthening component, the main component may include any one or more of metals such as aluminum, silver, copper, magnesium, etc., and the strengthening component may include any one or more of various metals such as molybdenum, titanium, tungsten and nickel. Of course, in some possible embodiments, the seed layer may also be a single metal layer, which only needs to be able to achieve the subsequent electroplating function, and is not specifically limited here.

[0099] In some embodiments, the width of the first sub-grid pre-plating layer 211 and the second sub-grid pre-plating layer 221 may be 0.03 mm-1 mm.

[0100] Thus, setting the width of the first sub-gate pre-plating layer 211 and the second sub-gate pre-plating layer 221 within a reasonable range of 0.03 mm to 1 mm can ensure the electroplating effect while forming a reliable ohmic contact with the silicon wafer 10 .

[0101] Specifically, in such an embodiment, the width of the first sub-gate pre-plating layer 211 and the second sub-gate pre-plating layer 221 may be, for example, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm or any value between 0.03mm-1mm, and is not limited here.

[0102] Further, in such an embodiment, the width of the first sub-grid pre-plating layer 211 and the second sub-grid pre-plating layer 221 may preferably be 0.03 mm-0.6 mm.

[0103] Specifically, the inventors of the present application have found through verification and research that if the width of the first auxiliary gate pre-plating layer 211 and the second auxiliary gate pre-plating layer 221 is less than 0.03 mm, it will easily lead to unstable ohmic contact between them and the silicon wafer 10, and will also affect the subsequent electroplating effect. If the width of the first auxiliary gate pre-plating layer 211 and the second auxiliary gate pre-plating layer 221 is greater than 0.6 mm, it will lead to a significant increase in cost. Therefore, setting the width of the first auxiliary gate pre-plating layer 211 and the second auxiliary gate pre-plating layer 221 within the preferred range of 0.03 mm-0.6 mm can effectively reduce costs while ensuring contact reliability and electroplating effect.

[0104] Embodiment 9

[0105] See also Figure 7 and Figure 8 , Figure 7 for Figure 3 A cross-sectional view along the second direction at the position of the first main grid 23, Figure 8 for Figure 3In the cross-sectional view along the second direction at the position of the second main grid 24, in some embodiments, the first main grid 23 may include a first main grid pre-plating layer 231 in contact with the first auxiliary grid pre-plating layer 211 and a first main grid electroplating layer 232 plated on the first main grid pre-plating layer 231, and the second main grid 24 includes a second main grid pre-plating layer 241 in contact with the second auxiliary grid pre-plating layer 221 and a second main grid electroplating layer 242 plated on the second main grid pre-plating layer 241.

[0106] In this way, by making the first main grid 23 and the second main grid 24 include a pre-plating layer and an electroplating layer, the seed layer of the main grid can be thickened and widened by electroplating, thereby improving the conductivity of the first main grid 23 and the second main grid 24. At the same time, forming the main grid by electroplating can also reduce the use of silver paste.

[0107] Specifically, in such an embodiment, the first main grid electroplating layer 232 and the second main grid electroplating layer 242 may also be electroplated copper layers. Like the first auxiliary grid pre-plating layer 211 and the second auxiliary grid pre-plating layer 221, in some embodiments, the first main grid pre-plating layer 231 and the second main grid pre-plating layer 241 may both include a seed layer, and the seed layer may be made by a physical vapor deposition method.

[0108] Specifically, the seed layers of the first busbar 23 and the second busbar 24 may be made of a metal material, which may preferably be an alloy material. In some embodiments, the main component of the seed layer may include copper, aluminum, or nickel.

[0109] It is understood that in some embodiments, the seed layer may include a main component and a strengthening component, the main component may be one or more of aluminum, silver, copper, and magnesium, and the strengthening component may include any one or more of a variety of metals such as molybdenum, titanium, tungsten, and nickel. Of course, in some possible embodiments, the seed layer may also be a single metal layer, as long as it can realize the subsequent electroplating function, and there is no specific limitation here.

[0110] In addition, in some embodiments, the first busbar pre-plating layer 231 and the second busbar pre-plating layer 241 may also be made by a light-induced electroplating method or a chemical plating method, which is not specifically limited herein. In this case, the first busbar pre-plating layer 231 and the second busbar pre-plating layer 241 may contain copper or nickel.

[0111] Embodiment 10

[0112] In some embodiments, the cross-sectional area of ​​the first main grid 23 and the second main grid 24 is 1000 um. 2 -50000um 2 .

[0113] In this way, since each electrode structure 20 has only one first main grid 23 and one second main grid 24, by reasonably setting the cross-sectional area of ​​the main grid, the current carrying capacity of the main grid can be improved while facilitating process implementation, thereby ensuring the reliability of the sliced ​​battery 101 and avoiding the first main grid 23 and the second main grid 24 from being too small in current carrying capacity and thus melting.

[0114] Specifically, in such an embodiment, the cross-sectional area of ​​the first main grid 23 and the second main grid 24 may be 1000 μm. 2 、1500um 2 、2000um 2 、2500um 2 、3000um 2 、3500um 2 、4000um 2 、5000um 2 、6000um 2 、7000um 2 、8000um 2 、9000um 2 、10000um 2 、15000um 2 、25000um 2 、30000um 2 、35000um 2 、40000um 2 、45000um 2 、50000um 2 Or 1000um 2 -50000um 2 Any value between , not limited here.

[0115] Embodiment 11

[0116] See also Fig. 9 In some embodiments, the back-contact solar cell 100 may not be sliced. In this case, the battery string 210 may include a plurality of back-contact solar cells 100. In each back-contact solar cell 100, the first main grid 23 of one of the adjacent electrode structures 20 is adjacent to the second main grid 24 of another one, the first main grid 23 and the second main grid 24 are connected by a conductive member 60, and the two adjacent back-contact solar cells 100 are connected by a welding strip.

[0117] In this way, since the polarities of the adjacent gate lines of the two electrode structures 20 are opposite, the potential difference of the non-electrode area between the two electrode structures 20 can be close to 0, so that the areas on both sides of the non-electrode area can work independently in the state of sliced ​​batteries without physically cutting the non-electrode area, achieving the same effect as the non-electrode area being physically cut. In this way, while achieving the slicing effect, the slicing steps and slicing equipment can be omitted, reducing costs.

[0118] It can be understood that in such an embodiment, in two adjacent back-contact solar cells 100, the adjacent main grids are main grids of different polarities, that is, in two adjacent back-contact solar cells 100, the first main grid 23 is adjacent to the second main grid 24, and the two can be connected by a welding strip.

[0119] In some embodiments, the first main gate 23 and the second main gate 24 are continuously arranged along the second direction, and the disconnection rate of the first main gate 23 and the second main gate 24 is less than 5%. In this way, since the adjacent main gates in the two electrode structures 20 have opposite properties and the disconnection rates are less than or equal to 5%, the potential difference in the non-electrode area can be made as low as possible.

[0120] It can be understood that if the polarity of the first main gate 23 and the second main gate 24 are opposite but the disconnection rate is too large, then the current of the secondary gate that cannot be intercepted at the disconnection point of the two is large, which will cause more leakage, and the potential difference cannot be made as low as possible. The areas on both sides of the non-electrode area can only be made to work independently through slicing. If the disconnection rates of the first main gate 23 and the second main gate 24 are both less than or equal to 5%, but the polarity of the first main gate 23 and the second main gate 24 are not opposite, the carriers of one of the main gates will pass through the non-electrode area directly from the surface of the silicon wafer 10 to the other main gate, and will not pass through the PN junction inside the silicon wafer 10, thereby causing serious leakage. The areas on both sides of the non-electrode area can only be made to work independently through slicing.

[0121] Specifically, the disconnection rate refers to the ratio of the length of the disconnected portion of the main grid to the total length of the main grid. In other words, the disconnection rate of the first main grid 23 refers to the ratio of the length of the disconnected portion of the first main grid 23 to the total length of the first main grid 23. The disconnection rate of the second main grid 24 refers to the ratio of the length of the disconnected portion of the second main grid 24 to the total length of the second main grid 24.

[0122] Specifically, the disconnection rate of the first main grid 23 is, for example, 5%, 4.8%, 4%, 2%, 1%, 0.1%, or 0%. The disconnection rate of the second main grid 24 is, for example, 5%, 4.8%, 4%, 2%, 1%, 0.1%, or 0%.

[0123] It can be understood that the disconnection rate of the first main grid 23 and the disconnection rate of the second main grid 24 can be the same or different.

[0124] In the present application, the disconnection rate of the first main grid 23 and the second main grid 24 is preferably 0%. In this way, the potential difference of the non-electrode area between the two electrode structures 20 is as close to 0 as possible, so that the areas on both sides of the non-electrode area can work independently in the state of sliced ​​cells without physically cutting the non-electrode area, achieving the same effect as the non-electrode area being physically cut, so that the areas on both sides of the non-electrode area work as independently as possible.

[0125] It is understood that in the present application, the conductive member 60 is used to electrically connect the adjacent first main grid 23 and the second main grid 24. In this way, the opposite main grids located on both sides of the non-electrode area can be efficiently connected to achieve the connection of the electrode structure 20 working independently in the two electrode areas.

[0126] In some embodiments, the conductive member 60 may include at least one of conductive glue, solder paste, or solder tape.

[0127] Specifically, in such an embodiment, the conductive member 60 may be formed by curing a conductive material, such as solder paste, conductive glue, etc.

[0128] Furthermore, in some embodiments, there are multiple conductive members 60, and the multiple conductive members 60 are spaced apart along the second direction, and the spacing between two adjacent conductive members 60 is less than or equal to 30 mm. For example, it is 30 mm, 28 mm, 25 mm, 20 mm, 18 mm, 10 mm, 5 mm, and 1 mm. In this way, the spacing between two adjacent conductive members 60 is within a suitable range, which can avoid the poor effect of electrically conducting the heterogeneous boundary main grid caused by too large a spacing.

[0129] Furthermore, the width of the conductive member 60 may be 0.5 mm to 2 mm. For example, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, and 2 mm. The width of the conductive member 60 refers to the size of the conductive member 60 in the second direction. In this way, the width of the conductive member 60 is within a suitable range, which can avoid easy breakage or difficult process due to too small a width, and can also avoid waste of materials and increased costs due to too large a width.

[0130] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A back contact solar cell, characterized in that: The invention comprises a silicon wafer and at least three electrode structures arranged on a backlight surface of the silicon wafer, wherein the at least three electrode structures are arranged at intervals along a first direction of the silicon wafer, and the electrode structures comprise: A plurality of first sub-grids and a plurality of second sub-grids, wherein the plurality of first sub-grids and the plurality of second sub-grids are alternately arranged in sequence and spaced apart along a second direction of the silicon wafer, and the second direction intersects the first direction; and A first main grid and a second main grid, wherein the first main grid and the second main grid are spaced apart along the first direction, the first main grid is located on one side of the first sub-grid and the second sub-grid and is connected to all ends of the first sub-grid, and the second sub-grid is located on the other side of the first sub-grid and the second sub-grid and is connected to all ends of the second sub-grid.

2. The back contact solar cell according to claim 1, characterized in that: Among the at least three electrode structures, the first main grid in at least one electrode structure is adjacent to the second main grid in another electrode structure.

3. The back contact solar cell according to claim 1, characterized in that: Among the at least three electrode structures, the first main grid in at least one electrode structure is adjacent to the first main grid in another electrode structure.

4. The back contact solar cell according to claim 3, characterized in that: When the first main gates of two adjacent electrode structures are adjacent to each other, a doping layer having the same polarity as that of the silicon wafer is provided in a spacing region between the two adjacent first main gates.

5. The back contact solar cell according to claim 1, characterized in that: The distance between two adjacent electrode structures is 0.6 mm to 1.6 mm.

6. The back contact solar cell according to claim 1, characterized in that: In the first direction, the distance between two adjacent electrode structures is twice the distance between the edgemost electrode structure and the edge of the silicon wafer.

7. The back contact solar cell according to claim 1, characterized in that: The cross-sectional area of ​​the first main grid and the second main grid is 1000um 2 -50000um 2 .

8. A battery string, characterized in that: The invention comprises a plurality of sliced ​​cells and connectors, wherein the sliced ​​cells are obtained by cutting and / or splitting the back contact solar cell according to any one of claims 1 to 7 along the interval between two adjacent electrode structures, and each sliced ​​cell comprises at least one electrode structure; Among the two adjacent sliced ​​batteries, the connecting member connects the first main grid of one of the sliced ​​batteries and the second main grid of the other sliced ​​battery.

9. A battery string, characterized in that: A back-contact solar cell comprising any one of claims 1-2 and 5-7, wherein in each back-contact solar cell, the first main grid of one of adjacent electrode structures is adjacent to the second main grid of another adjacent electrode structure, the first main grid and the second main grid are connected by a conductive member, and two adjacent back-contact solar cells are connected by a welding strip.

10. The battery string according to claim 9, characterized in that: The conductive member includes at least one of conductive glue, solder paste or solder tape.

11. The battery string according to claim 9, characterized in that: There are multiple conductive members, and the multiple conductive members are arranged at intervals along the second direction. The interval between two adjacent conductive members is less than or equal to 30 mm.

12. The battery string according to claim 11, characterized in that: The width of the conductive member is 0.5 mm-2 mm.

13. A battery assembly, characterized in that: A battery string comprising any one of several claims 8-12.

14. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 13.

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