Back contact battery, battery assembly and photovoltaic system

Abstract

The utility model provides a back contact battery, a battery assembly and a photovoltaic system. The back contact cell includes: a cell substrate; the doping layer is formed on the battery substrate, and the doping layer comprises an N-type doping region and a P-type doping region; the first fine grid is arranged in the N-type doped region; the second fine grid is arranged in the P-type doped region; the first main grid is conductively connected with the first fine grid; the second main grid is conductively connected with the second fine grid; wherein the ratio of the maximum width of the non-welding area of at least one second main grid to the maximum width of the non-welding area of at least one first main grid is 1.05-2. Therefore, the ratio of the maximum width of the non-welding area of the at least one second main grid to the maximum width of the non-welding area of the at least one first main grid is 1.05-2, so that the width of the second main grid can be increased, and the transmission efficiency of the second main grid to carriers in the P-type doped region can be increased by increasing the width of the second main grid; therefore, the photoelectric conversion efficiency of the back contact cell is improved.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic technology, and in particular to a back contact battery, battery module and photovoltaic system. Background Technology

[0002] In back-contact solar cells, the difficulty in boron doping leads to a low doping concentration in the P-type doped region, resulting in insufficient carriers and reduced photoelectric conversion efficiency. Current solutions aim to compensate for this by increasing the width of the P-type doped region; however, a wider P-type doped region introduces lateral current transport losses.

[0003] Therefore, finding a suitable combination of the width range of the P and N type doped regions, the width of the first fine gate in P, and the width of the main gate in P and N regions to minimize the transmission resistance and thus further improve the photoelectric conversion efficiency of the back contact cell has become an urgent problem to be solved. Utility Model Content

[0004] This invention provides a back-contact battery, a battery module, and a photovoltaic system to solve the technical problem of how to improve the photoelectric conversion efficiency of a back-contact battery.

[0005] The present invention is implemented as follows: the present invention provides a back contact battery, a battery module, and a photovoltaic system. A back-contact battery, comprising: a battery substrate; a doped layer formed on the battery substrate, the doped layer including N-type doped regions and P-type doped regions, the N-type doped regions and the P-type doped regions being alternately arranged along a first direction and both extending along a second direction, the first direction intersecting the second direction; a first fine grid disposed on the N-type doped regions and a second fine grid disposed on the P-type doped regions, the first fine grid being electrically connected to the N-type doped regions and the second fine grid being electrically connected to the P-type doped regions, the first fine grid and the second fine grid being alternately arranged along the first direction and both extending along the second direction, the first fine grid and the second fine grid having opposite conductivity types; a first main grid electrically connected to the first fine grid and a second main grid electrically connected to the second fine grid, the first main grid and the second main grid being alternately arranged along the second direction and both extending along the first direction, the first main grid and the second main grid having opposite conductivity types; wherein the ratio of the maximum width of the non-welded region of at least one second main grid to the maximum width of the non-welded region of at least one first main grid is 1.05 to 2.

[0006] Furthermore, the non-welded area of ​​the first main gate is a rectangular gate line or a wedge-shaped gate line; the non-welded area of ​​the second main gate is a rectangular gate line or a wedge-shaped gate line.

[0007] Furthermore, both the non-welded areas of the second main gate and the first main gate are rectangular gate lines, and the difference between the width of the non-welded area of ​​the second main gate and the width of the non-welded area of ​​the first main gate is 10µm to 1000µm.

[0008] Furthermore, both the non-welded regions of the second main gate and the first main gate are wedge-shaped gate lines; the difference between the minimum width of the non-welded region of the second main gate and the minimum width of the non-welded region of the first main gate is 10µm to 500µm; and / or, the difference between the maximum width of the non-welded region of the second main gate and the maximum width of the non-welded region of the first main gate is 10µm to 500µm.

[0009] Furthermore, both the non-welded areas of the second main gate and the first main gate are wedge-shaped gate lines; the wedge-shaped gate lines include a first trapezoidal portion and a second trapezoidal portion arranged along a first direction; in the second main gate, the width of the boundary line between the first trapezoidal portion and the second trapezoidal portion is a first width; in the first main gate, the width of the boundary line between the first trapezoidal portion and the second trapezoidal portion is a second width; the ratio of the first width to the second width is 1.05 to 2.

[0010] Furthermore, the difference between the first width and the second width is 10um to 500um.

[0011] Furthermore, the ratio of the maximum width of the non-welded region of at least one of the second main gates to the width of at least one of the P-type doped regions is 1.5 to 10.

[0012] Furthermore, the ratio of the maximum width of the non-welded region of at least one of the second main gates to the width of at least one of the P-type doped regions is 3 to 8.

[0013] Furthermore, the ratio of the width of at least one of the second fine gates to the width of at least one of the P-type doped regions is 0.1 to 0.8.

[0014] Furthermore, the ratio of the width of at least one of the second fine gates to the width of at least one of the P-type doped regions is 0.2 to 0.5.

[0015] Furthermore, the ratio of the maximum width of the non-welded area of ​​at least one second main gate to the width of at least one second fine gate is 8 to 100.

[0016] Furthermore, the ratio of the maximum width of the non-welded region of at least one of the second main gates to the width of at least one of the P-type doped regions is greater than the ratio of the maximum width of the first main gate to the width of at least one of the N-type doped regions.

[0017] This utility model embodiment also provides a battery assembly, which includes the back contact battery described above.

[0018] This utility model embodiment also provides a photovoltaic system, which includes the battery module as described above.

[0019] In this application, the maximum width of the non-welded region of at least one second main gate is 1.05 to 2, which increases the width of the second main gate. By increasing the width of the second main gate, the transport efficiency of the second main gate to the carriers in the P-type doped region can be increased, thereby improving the photoelectric conversion efficiency of the back contact cell. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a photovoltaic system module provided in one embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of a battery assembly provided in one embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of a back contact battery provided in one embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the structure of a back contact battery provided in another embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the structure of a back contact battery provided in another embodiment of this utility model;

[0026] Figure 6 This is a schematic diagram of the structure of a back contact battery provided in another embodiment of the present invention;

[0027] Figure 7 This is a schematic diagram of the structure of the rectangular first main grid in a back contact battery according to an embodiment of the present invention;

[0028] Figure 8 This is a schematic diagram of the rectangular second main grid in a back contact battery according to an embodiment of the present invention;

[0029] Figure 9This is a schematic diagram of the structure of the wedge-shaped first main grid in a back contact battery according to an embodiment of the present invention;

[0030] Figure 10 This is a schematic diagram of the structure of the wedge-shaped second main grid in a back contact battery according to an embodiment of the present invention;

[0031] Figure 11 This is a schematic diagram of the structure of the wedge-shaped first main grid in a back contact battery provided in another embodiment of the present invention;

[0032] Figure 12 This is a schematic diagram of the structure of the wedge-shaped second main grid in a back contact battery provided in another embodiment of the present invention.

[0033] Key component symbols: 1000, Photovoltaic system; 1001, Battery module; 100, Back contact cell; 10, Battery substrate; 21, N-type doped region; 22, P-type doped region; 31, First fine grid; 32, Second fine grid; 41, First main grid; 42, Second main grid; 401, First trapezoidal section; 402, Second trapezoidal section; 411, Welding area; 412, Non-welding area. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present utility model, and should not be construed as limiting the present utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining the present utility model and are not intended to limit the present utility model.

[0035] In the description of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "top", "bottom", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0037] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for mutual communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0038] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0039] Please see Figure 1 and Figure 2 The photovoltaic system 1000 in this embodiment of the present invention may include the battery module 1001 in this embodiment of the present invention. The battery module 1001 in this embodiment of the present invention may include a plurality of back contact batteries 100 in this embodiment of the present invention. The plurality of back contact batteries 100 may be connected in series to form a battery string. The battery strings in the battery module 1001 may be connected in series, in parallel, or in a series-parallel combination to achieve current collection and output. For example, the connection between the battery strings may be achieved by a bus bar.

[0040] In this embodiment, the photovoltaic system 1000 can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy for power generation, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system 1000 are not limited to these; that is, the photovoltaic system 1000 can be applied in all fields that require solar energy for power generation. Taking a photovoltaic power generation system network as an example, the photovoltaic system 1000 may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules 1001. For example, multiple battery modules 1001 can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0041] The accompanying drawings provided by this utility model are schematic diagrams, and some elements are not shown in the drawings. The purpose is to clearly describe the technical solution and highlight the key points of the utility model. It is not intended to limit the technical solution to exclude these unshown elements. That is to say, the drawings are merely examples and do not represent a limitation on the specific form of the back contact battery 100.

[0042] like Figures 3 to 6 As shown, the back contact battery 100 in this embodiment of the present invention includes: a battery substrate 10, a doped layer, a second fine grid 32, a first fine grid 31, a second main grid 42, and a first main grid 41. The doped layer is formed on the battery substrate 10 and includes an N-type doped region 21 and a P-type doped region 22. The N-type doped region 21 and the P-type doped region 22 are arranged alternately along a first direction and both extend along a second direction, with the first direction intersecting the second direction. A first fine gate 31 is disposed in an N-type doped region 21, and a second fine gate 32 is disposed in a P-type doped region 22. The first fine gate 31 is electrically connected to the N-type doped region 21, and the second fine gate 32 is electrically connected to the P-type doped region 22. The first fine gate 31 and the second fine gate 32 are arranged alternately along a first direction and both extend along a second direction. The first fine gate 31 and the second fine gate 32 have opposite conductivity types. A first main gate 41 is electrically connected to the first fine gate 31, and a second main gate 42 is electrically connected to the second fine gate 32. The first main gate 41 and the second main gate 42 are arranged alternately along the second direction and both extend along the first direction. The first main gate 41 and the second main gate 42 have opposite conductivity types. The maximum width W of the non-welded region 412 of at least one second main gate 42 is... P主 The maximum width W of the non-welded area 412 of at least one first main gate 41 N主 The ratio is between 1.05 and 2.

[0043] Thus, the maximum width W of the non-welded area 412 of at least one second main gate 42 in this application isP主 The maximum width W of the non-welded area 412 of at least one first main gate 41 N主 The ratio is 1.05 to 2, which can increase the width of the second main gate 42. By increasing the width of the second main gate 42, the transport efficiency of the second main gate 42 to the carriers in the P-type doped region 22 can be increased, thereby improving the photoelectric conversion efficiency of the back contact cell 100.

[0044] The battery substrate 10 is specifically the main body of the back contact battery 100. For example, the battery substrate 10 may include a silicon substrate, and may also include a dielectric layer, a doped layer, a passivation layer, etc., which can be set according to the actual situation.

[0045] A doped layer is provided on the battery substrate 10. The doped layer includes an N-type doped region 21 and a P-type doped region 22. The N-type doped region 21 has N-type charge carriers, and the P-type doped region 22 has P-type charge carriers. A second fine gate 32 is disposed on the P-type doped region 22 and is electrically connected to it. The second fine gate 32 is used to collect charge carriers in the P-type doped region 22. A first fine gate 31 is disposed on the N-type doped region 21 and is electrically connected to it. The first fine gate 31 is used to collect charge carriers in the N-type doped region 21. A second main gate 42 and a first main gate 41 are also provided on the doped layer. The second main gate 42 is electrically connected to the second fine gate 32, thereby merging the charge carriers collected by the second fine gate 32; the first main gate 41 is electrically connected to the first fine gate 31, thereby merging the charge carriers collected by the first fine gate 31.

[0046] It is understandable that because boron is difficult to dope, the doping concentration of the P-type doped region 22 is relatively low, which in turn results in a lower number of charge carriers collected in the P-type doped region 22, thereby reducing the photoelectric conversion efficiency of the back contact cell 100.

[0047] like Figures 7 to 10 As shown, both the first main gate 41 and the second main gate 52 have a welding area 411 for welding and a non-welding area 412 not used for welding.

[0048] In this embodiment of the invention, the maximum width W of the non-welded area 412 of the second main gate 42 is set. P主 The maximum width W of the non-welded area 412 of the first main gate 41 is greater than the maximum width of the non-welded area 412. N主 This allows for an increase in the overall width of the second main gate 42, reducing its conductivity and thus improving the carrier collection efficiency in the P-type doped region 22, further enhancing the photoelectric conversion efficiency of the back contact cell 100. Simultaneously, in the cell assembly 1001, the maximum width W of the non-welded region 412 of the second main gate 42 is set. P主 The maximum width W of the non-welded area 412 of the first main gate 41 is greater than the maximum width of the non-welded area 412.N主 It can also increase the contact area between the second main grid 42 and the solder strip, further reduce the contact resistance when the solder joint contacts the battery, thereby enhancing the conductivity of the P-type doped region 22, improving the carrier collection efficiency, and further improving the battery efficiency of the battery module 1001.

[0049] Furthermore, the maximum width W of the non-welded area 412 of the second main gate 42 in this application P主 The maximum width W of the non-welded area 412 of the first main gate 41 N主 The ratio is between 1.05 and 2. This allows for increasing the width of the second main gate 42 while avoiding an excessively small width of the first main gate 41, which could affect the carrier collection efficiency in the N-type doped region 21. It is understood that the main gate can be either a rectangular gate line or a wedge-shaped gate line. When the main gate is a wedge-shaped gate line, it has both wider and narrower positions. When the main gate is a rectangular gate line, due to manufacturing process variations, the width of the rectangular gate line may not be uniform across different positions, also resulting in both wider and narrower positions.

[0050] In one possible implementation, the second main gate 42 is a rectangular gate line or a wedge-shaped gate line; the first main gate 41 is a rectangular gate line or a wedge-shaped gate line.

[0051] It is understandable that "the maximum width W of the non-welded area 412 of the second main gate 42" P主 "This refers to the width of the non-welded area 412 in the second main gate 42 where the width is the largest." "The maximum width W of the non-welded area 412 of the first main gate 41..." N主 "This refers to the width of the position where the width of the non-welded area 412 in the first main gate 41 is the largest.

[0052] For example, the maximum width W of the non-welded area 412 of the second main gate 42 P主 The maximum width W of the non-welded area 412 of the first main gate 41 N主 The ratios are 1.05, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2. Preferably, the maximum width W of the non-welded area 412 of the second main gate 42 is... P主 The maximum width W of the non-welded area 412 of the first main gate 41 N主 When the ratio is 2, the collection efficiency of P-region carriers can be maximized while avoiding a decrease in the collection efficiency of N-region carriers, thus achieving the best battery efficiency for the back contact battery 100.

[0053] In this application, in order to verify the adjustment of the maximum width W of the non-welded area 412 of the second main gate 42 P主The impact on the performance of the back contact battery 100, specifically the maximum width W of the non-welded region 412 of the second main grid 42. P The maximum width W of the first main gate 41 N主 Different proportions were tested. The test results are shown in the table below.

[0054]

[0055] From the table above, we can see that the maximum width W of the non-welded area 412 of the second main gate 42 is... P主 The maximum width W of the non-welded area 412 of the first main gate 41 N主 When the ratio is 1.05 to 2, the efficiency of the back contact battery 100 can be effectively improved. Simultaneously, the maximum width W of the non-welded area 412 of the second main gate 42... P主 The maximum width W of the non-welded area 412 of the first main gate 41 N主 When the ratio is greater than 2, the width of the first main gate 41 needs to be reduced because the width of the second main gate 42 is too large, which affects the collection of N-type carriers and thus reduces the efficiency of the back contact cell 100.

[0056] like Figure 3 and Figure 4 As shown, in one possible implementation, both the second main gate 42 and the first main gate 41 are rectangular gate lines. The difference between the width of the non-welded region 412 of the second main gate 42 and the width of the non-welded region 412 of the first main gate 41 is 10µm to 1000µm. For example, 10µm, 50µm, 100µm, 200µm, 300µm, 400µm, 500µm, 600µm, 700µm, 800µm, 900µm, and 1000µm. Thus, by further increasing the width of the second main gate 42, the transport efficiency of the second main gate 42 for carriers in the P-type doped region 22 can be increased, thereby improving the photoelectric conversion efficiency of the back contact cell 100. Simultaneously, while increasing the width of the second main gate 42, it is possible to avoid the first main gate 41 being too narrow, which would affect the carrier collection efficiency in the N-type doped region 21.

[0057] It is understandable that referring to the second main gate 42 and the first main gate 41 as rectangular gate lines means that the second main gate 42 and the first main gate 41 appear rectangular from a macroscopic perspective. Due to manufacturing process limitations, the second main gate 42 and the first main gate 41 may not be perfectly rectangular. For example, if the second main gate 42 and the first main gate 41 have certain protrusions on their sides, and the tilt angle of the second main gate 42 and the first main gate 41 is within 2°, and the protrusion height of the second main gate 42 and the first main gate 41 is within 200µm, they can be considered rectangular.

[0058] Understandably, in a back-contact battery 100, if the width of the non-welded area 412 of the second main gate 42 is too large, the second main gate 42 will compress the installation space of the first main gate 41, and the width of the first main gate 41 needs to be reduced accordingly. Therefore, the width of the second main gate 42 cannot be too large.

[0059] Furthermore, increasing the width of the non-welded region 412 of the second main gate 42 increases the total amount of main gate paste used, thereby increasing the manufacturing cost of the back contact battery 100. Therefore, in this embodiment of the invention, by setting the difference between the width of the non-welded region 412 of the second main gate 42 and the width of the non-welded region 412 of the first main gate 41 to be 10µm to 1000µm, the collection efficiency of P-type carriers can be improved while avoiding an excessively large width of the second main gate 42 and an excessively large total amount of main gate paste used, thereby saving costs and preventing the manufacturing cost of the back contact battery 100 from becoming too high.

[0060] For example, when both the second main gate 42 and the first main gate 41 are rectangular gate lines, the width of the non-welded area 412 of the second main gate 42 can be set to 500um to 1600um, for example, the width of the second main gate 42 is 500um, 580um, 590um, 600um, 800um, 900um, 1000um, 1200um, 1300um, 1500um, or 1600um.

[0061] like Figure 5 and Figure 6 As shown, in one possible implementation, both the non-welded region 412 of the second main gate 42 and the non-welded region 412 of the first main gate 41 are wedge-shaped gate lines; the minimum width W of the non-welded region 412 of the second main gate 42 is... P小 The minimum width W of the non-welded area 412 of the first main gate 41 N小 The difference is from 10um to 500um, for example, 10um, 20um, 50um, 60um, 100um, 150um, 200um, 250um, 300um, 350um, 400um, 450um, 500um; and / or, the maximum width W of the non-welded area 412 of the second main gate 42. P主 The maximum width W of the non-welded area 412 of the first main gate 41 N主The difference ranges from 10µm to 500µm, for example, 10µm, 20µm, 50µm, 60µm, 100µm, 150µm, 200µm, 250µm, 300µm, 350µm, 400µm, 450µm, and 500µm. Thus, by further increasing the width of the non-welded region 412 of the second main gate 42, the transport efficiency of the second main gate 42 for carriers in the P-type doped region 22 can be increased, thereby improving the photoelectric conversion efficiency of the back contact cell 100. Simultaneously, while increasing the width of the second main gate 42, it is possible to avoid the first main gate 41 being too narrow, which would affect the carrier collection efficiency in the N-type doped region 21.

[0062] Similarly, increasing the width of the non-welded area 412 of the second main grid 42 increases the total amount of grid paste used, thereby increasing the manufacturing cost of the back contact battery 100. Therefore, in this embodiment of the invention, by setting the minimum width W of the non-welded area 412 of the second main grid 42... P小 The minimum width W of the non-welded area 412 of the first main gate 41 N小 The difference is 10µm to 500µm, and / or the maximum width W of the non-welded area 412 of the second main gate 42. P主 The maximum width W of the non-welded area 412 of the first main gate 41 N主 The difference is 10um to 500um. It can also improve the collection efficiency of P-type carriers while avoiding an excessively large width of the non-welded area 412 of the second main grid 42 and an excessively large total amount of main grid paste, thereby saving costs and avoiding excessive manufacturing costs of the back contact cell 100.

[0063] For example, when both the non-welded area 412 of the second main gate 42 and the non-welded area 412 of the first main gate 41 are wedge-shaped gate lines, the maximum width of the non-welded area 412 of the second main gate 42 can be set to 200um to 800um, for example, the maximum width of the non-welded area 412 of the second main gate 42 is 200um, 250um, 290um, 300um, 350um, 400um, 500um, 500um, 600um, 650um, 700um, or 800um.

[0064] For example, when both the non-welded area 412 of the second main gate 42 and the non-welded area 412 of the first main gate 41 are wedge-shaped grid lines, the minimum width of the non-welded area 412 of the second main gate 42 can be set to 70µm to 700µm. For example, the minimum width of the non-welded area 412 of the second main gate 42 can be 70µm, 90µm, 100µm, 130µm, 140µm, 200µm, 250µm, 300µm, 350µm, 400µm, 450µm, 500µm, 600µm, or 700µm. Of course, in the back contact battery 100, all the non-welded areas 412 of the main gate can be set to rectangular grid lines; or, all the non-welded areas 412 of the main gate can be set to wedge-shaped grid lines; or, a portion of the non-welded areas 412 of the main gate can be set to wedge-shaped grid lines and a portion of the non-welded areas 412 of the main gate can be set to rectangular grid lines. No limitation is made here.

[0065] like Figure 5 , Figure 6 , Figure 9 , Figure 10 , Figure 11 , Figure 12 As shown, in one possible implementation, both the non-welded region 412 of the second main gate 42 and the non-welded region 412 of the first main gate 41 are wedge-shaped gate lines. The non-welded region 412 of the wedge-shaped gate line includes a first trapezoidal portion 401 and a second trapezoidal portion 402 arranged along a first direction. In the second main gate 42, the width of the boundary line between the first trapezoidal portion 401 and the second trapezoidal portion 402 is a first width Y1. In the first main gate 41, the width of the boundary line between the first trapezoidal portion 401 and the second trapezoidal portion 402 is a second width Y2. The ratio of the first width Y1 to the second width Y2 is 1.05 to 2. In this way, while increasing the width of the second main gate 42, it is possible to avoid the width of the first main gate 41 being too small, thereby affecting the carrier collection efficiency in the N-type doped region 21.

[0066] For example, the ratio of the first width Y1 to the second width Y2 is 1.05, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2. Preferably, when the ratio of the first width Y1 to the second width Y2 is 2, the collection efficiency of carriers in the P-region can be maximized while avoiding a decrease in the collection efficiency of carriers in the N-region, resulting in the best battery efficiency for the back contact battery 100.

[0067] It is understood that when the second main gate 42 and the first main gate 41 are wedge-shaped gate lines, the second main gate 42 and the first main gate 41 have a first trapezoidal portion 401 and a second trapezoidal portion 402 arranged along a first direction. It is understood that the first trapezoidal portion 401 and the second trapezoidal portion 402 appear as trapezoids from a macroscopic perspective. Due to manufacturing process reasons, the first trapezoidal portion 401 and the second trapezoidal portion 402 may not be absolutely trapezoidal. For example, the sides of the first trapezoidal portion 401 and the second trapezoidal portion 402 may have certain protrusions, and the tilt angle of the first trapezoidal portion 401 and the second trapezoidal portion 402 is within 2°, which can be considered as trapezoidal.

[0068] like Figure 5 , Figure 6 , Figure 9 , Figure 10 , Figure 11 , Figure 12 As shown, further, the difference between the first width Y1 and the second width Y2 is 10µm to 500µm. For example, it can be 10µm, 20µm, 50µm, 60µm, 100µm, 150µm, 200µm, 250µm, 300µm, 350µm, 400µm, 450µm, or 500µm. In this way, by further increasing the width of the second main gate 42, the transport efficiency of the second main gate 42 for carriers in the P-type doped region 22 can be increased, thereby improving the photoelectric conversion efficiency of the back contact cell 100. At the same time, while increasing the width of the second main gate 42, it is also possible to avoid the first main gate 41 being too narrow, which would affect the carrier collection efficiency in the N-type doped region 21.

[0069] like Figures 3 to 10 As shown, in one possible implementation, the maximum width W of the non-welded region 412 of at least one second main gate 42 is... P主 With at least one p-type doped region 22, the width W P区 The ratio is between 1.5 and 10. For example, ratios are 1.5, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9, and 10. It is understandable that as the width W of the p-type doped region 22 increases... P区 At the same time, the number of charge carriers in the P-type doped region 22 will also increase accordingly. Furthermore, if the width of the non-welded region 412 of the second main gate 42 is insufficient, the carrier collection capacity of the second main gate 42 will be insufficient. Therefore, by setting the maximum width W of the non-welded region 412 of the second main gate 42... P主 The width W of the p-type doped region 22 P区 The ratio is 4 to 10, which can expand the current carrying capacity of the second main grid 42, thereby improving the photoelectric conversion efficiency of the back contact cell 100.

[0070] Preferably, the maximum width W of the non-welded area 412 of at least one second main gate 42P主 With at least one p-type doped region 22, the width W P区 The ratio can be set to 3 to 8. For example, 3, 3.5, 4, 5, 6, 7, 8. In this way, the current carrying capacity of the second main gate 42 can be increased, and the width of the first main gate 41 can be avoided if it is too small, which would affect the carrier collection efficiency in the N-type doped region 21.

[0071] like Figures 3 to 10 As shown, in one possible implementation, the maximum width W of the non-welded region 412 of at least one second main gate 42 is... P主 With at least one p-type doped region 22, the width W P区 The ratio is greater than the maximum width W of the non-welded area 412 of at least one first main gate 41. N主 With at least one N-type doped region 21, the width W N区 This ratio allows the second main gate 42 to better collect carriers in the P-type doped region 22, thereby improving the photoelectric conversion efficiency of the back contact cell 100.

[0072] like Figures 3 to 10 As shown, in one possible implementation, the width W of at least one second fine gate 32 P细 With at least one p-type doped region 22, the width W P区 The ratio is between 0.1 and 0.8. For example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8. This allows the second fine gate 32 to adequately collect carriers in the p-type doped region 22 while avoiding an increase in the width W of the second fine gate 32. P细 Too large, thus avoiding increasing the cost of the back contact battery 100.

[0073] Preferably, the width W of at least one second fine grid 32 P细 With at least one p-type doped region 22, the width W P区 The ratio is between 0.2 and 0.5. For example, 0.2, 0.3, 0.4, and 0.5. In this way, the carrier collection of the second fine gate 32 can be further improved while reducing the cost of the back contact cell 100.

[0074] like Figures 3 to 10 As shown, in one possible implementation, the maximum width W of the non-welded region 412 of at least one second main gate 42 is... P主 With the width W of at least one second fine grid 32 P细 The ratio is between 8 and 100. In this way, while increasing the width of the second main gate 42, it is possible to avoid the second main gate 42 becoming too large and thus compressing the space for the second fine gate 32, resulting in the width W of the second fine gate 32 being... P细 If the size is too small, the second fine gate 32 will not be able to fully collect the carriers in the P-type doped region 22.

[0075] It is understood that in such an embodiment, the battery assembly 1001 may further include a frame, a back sheet, photovoltaic glass, and an encapsulating film. The encapsulating film may be filled between the front and back surfaces of the back contact battery 100, the photovoltaic glass, and adjacent back contact batteries 100, etc. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film may be an EVA film or a POE film, and the specific choice can be made according to the actual situation, without limitation.

[0076] Photovoltaic glass can be applied to the encapsulating film on the front side of the back contact cell 100. The photovoltaic glass can be ultra-clear glass, which has high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%. It can protect the back contact cell 100 while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the back contact cell 100 together, providing sealing, insulation, and waterproofing / moisture protection for the back contact cell 100.

[0077] The backsheet can be attached to the adhesive film on the back side of the back contact cell 100. The backsheet provides protection and support for the back contact cell 100, and has reliable insulation, water resistance, and aging resistance. Multiple options are available for the backsheet, typically tempered glass, acrylic glass, aluminum alloy TPT composite adhesive film, etc., and the specific choice is determined based on the specific circumstances and is not limited here. The backsheet, back contact cell 100, adhesive film, and photovoltaic glass can be integrated into a frame. The frame serves as the main external support structure for the entire battery module 1001, providing stable support and installation for the battery module 1001. For example, the battery module 1001 can be installed at the desired location via the frame.

[0078] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0079] Furthermore, the above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A back-contact battery, characterized in that, include: Battery substrate; A doped layer is formed on the battery substrate. The doped layer includes N-type doped regions and P-type doped regions. The N-type doped regions and the P-type doped regions are arranged alternately along a first direction and both extend along a second direction. The first direction and the second direction intersect. A first fine gate is disposed in the N-type doped region and a second fine gate is disposed in the P-type doped region. The first fine gate is electrically connected to the N-type doped region and the second fine gate is electrically connected to the P-type doped region. The first fine gate and the second fine gate are alternately arranged along the first direction and both extend along the second direction. The first fine gate and the second fine gate have opposite conductivity types. A first main gate conductively connected to the first fine gate and a second main gate conductively connected to the second fine gate, the first main gate and the second main gate are alternately arranged along the second direction and both extend along the first direction, the first main gate and the second main gate have opposite conductivity types; The ratio of the maximum width of the non-welded area of ​​at least one second main gate to the maximum width of the non-welded area of ​​at least one first main gate is 1.05 to 2.

2. The back contact battery according to claim 1, characterized in that, The non-welded area of ​​the first main gate is a rectangular gate line or a wedge-shaped gate line; The non-welded area of ​​the second main gate is a rectangular grid line or a wedge-shaped grid line.

3. The back contact battery according to claim 1, characterized in that, Both the non-welded area of ​​the second main gate and the non-welded area of ​​the first main gate are rectangular gate lines, and the difference between the width of the non-welded area of ​​the second main gate and the width of the non-welded area of ​​the first main gate is 10um to 1000um.

4. The back contact battery according to claim 1, characterized in that, Both the non-welded areas of the second main gate and the non-welded areas of the first main gate are wedge-shaped gate lines; The difference between the minimum width of the non-welded area of ​​the second main gate and the minimum width of the non-welded area of ​​the first main gate is 10µm to 500µm; and / or, The difference between the maximum width of the non-welded area of ​​the second main gate and the maximum width of the non-welded area of ​​the first main gate is 10µm to 500µm.

5. The back contact battery according to claim 1, characterized in that, Both the non-welded areas of the second main gate and the non-welded areas of the first main gate are wedge-shaped gate lines; the wedge-shaped gate lines include a first trapezoidal portion and a second trapezoidal portion arranged along a first direction; In the second main gate, the width of the boundary line between the first trapezoidal portion and the second trapezoidal portion is the first width; In the first main gate, the width of the boundary line between the first trapezoidal portion and the second trapezoidal portion is the second width; The ratio of the first width to the second width is 1.05 to 2.

6. The back contact battery according to claim 5, characterized in that, The difference between the first width and the second width is 10um to 500um.

7. The back contact battery according to claim 1, characterized in that, The ratio of the maximum width of the non-welded region of at least one of the second main gates to the width of at least one of the P-type doped regions is 1.5 to 10.

8. The back contact battery according to claim 7, characterized in that, The ratio of the maximum width of the non-welded region of at least one of the second main gates to the width of at least one of the P-type doped regions is 3 to 8.

9. The back contact battery according to claim 1, characterized in that, The width of at least one of the second fine gates is in the ratio of 0.1 to 0.8 to the width of at least one of the P-type doped regions.

10. The back contact battery according to claim 9, characterized in that, The width of at least one of the second fine gates is 0.2 to 0.5 times the width of at least one of the P-type doped regions.

11. The back contact battery according to claim 1, characterized in that, The ratio of the maximum width of the non-welded area of ​​at least one second main gate to the width of at least one second fine gate is 8 to 100.

12. The back contact battery according to claim 1, characterized in that, The ratio of the maximum width of the non-welded region of at least one of the second main gates to the width of at least one of the P-type doped regions is greater than the ratio of the maximum width of the first main gate to the width of at least one of the N-type doped regions.

13. A battery assembly, characterized in that, The battery assembly includes a back-contact battery as described in any one of claims 1 to 2.

14. A photovoltaic system, characterized in that, The photovoltaic system includes the battery module as described in claim 13.

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