Back contact battery, battery assembly and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a back contact cell, a cell assembly and a photovoltaic system. The back contact cell comprises a silicon substrate, a plurality of first auxiliary grids and a plurality of second auxiliary grids. The first auxiliary gate and the second auxiliary gate are respectively connected with an N-type doped region and a P-type doped region of the silicon substrate, and the resistivity of the silicon substrate of the silicon substrate is greater than or equal to 30 omega.cm; the first auxiliary grids and the second auxiliary grids extend along the first direction, are mutually spaced and are arranged along the first direction to form a row of auxiliary grid groups; the plurality of rows of auxiliary grid groups are mutually spaced and are sequentially arranged along a second direction, and the second direction is crossed with the first direction; in all the auxiliary grid groups, the ratio of the total length of the first auxiliary grids to the total length of the second auxiliary grids is 0.66-1.2. Therefore, in the back contact battery with the silicon substrate with low doping concentration, the sum of the lengths of the P-type doped regions can be ensured to be large enough, so that effective collection of hole carriers can be ensured.

Description

Technical Field

[0001] The present application belongs to the technical field of solar cells, and in particular relates to a back-contact cell, a cell assembly and a photovoltaic system. Background Art

[0002] A solar cell in which electrodes of both polarities are formed on the back of the cell is a back contact cell. In the back contact cell of the related art, the two polarity sub-grids are usually arranged alternately in the width direction of the sub-grid, and the sub-grids of each polarity extend in the length direction of the sub-grid. However, in this way, the hole collection ability of the cell is poor.

[0003] Based on this, how to enhance the hole collection ability of the battery has become an urgent problem to be solved. Utility Model Content

[0004] The present application provides a back-contact cell, a cell assembly and a photovoltaic system, aiming to solve the problem of how to enhance the hole collection capability of the cell.

[0005] The back contact cell provided in the present application comprises a silicon substrate, a plurality of first sub-grids and a plurality of second sub-grids;

[0006] The first auxiliary gate and the second auxiliary gate are respectively connected to an N-type doping region and a P-type doping region of the silicon substrate, and the resistivity of the silicon substrate of the silicon substrate is greater than 30Ω·cm;

[0007] The first auxiliary grid and the second auxiliary grid extend along the first direction, are spaced from each other, and are arranged along the first direction to form a row of auxiliary grid groups; a plurality of rows of auxiliary grid groups are spaced from each other and are arranged in sequence along a second direction, and the second direction intersects the first direction;

[0008] In all the auxiliary grid groups, the ratio of the total length of the first auxiliary grid to the total length of the second auxiliary grid is 0.66-1.2.

[0009] The battery assembly provided in the present application comprises a plurality of electrical connectors and a plurality of back-contact batteries of any one of the above items, wherein the electrical connectors connect a first sub-grid of one of the back-contact batteries and a second sub-grid of an adjacent back-contact battery.

[0010] The photovoltaic system provided in the present application includes any one of the above-mentioned battery components.

[0011] The back-contact cell, cell assembly and photovoltaic system of the embodiments of the present application, since the resistivity of the silicon substrate is greater than or equal to 30Ω·cm, and the ratio of the total length of the first sub-gate connected to the N-type doped region to the total length of the second sub-gate connected to the P-type doped region in all sub-gate groups is 0.66-1.2, it can be ensured that in the back-contact cell with a silicon substrate with a low doping concentration, the sum of the lengths of the P-type doped regions is large enough, thereby ensuring the effective collection of hole carriers. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic structural diagram of a back contact battery according to an embodiment of the present application;

[0013] Figure 2 is a schematic diagram of the structure of a battery string according to an embodiment of the present application;

[0014] Figure 3 is a schematic structural diagram of a partial area of ​​a back contact battery according to an embodiment of the present application;

[0015] Figure 4 A schematic structural diagram of a back contact battery according to an embodiment of the present application;

[0016] Figure 5 is a schematic structural diagram of a back contact battery according to an embodiment of the present application;

[0017] Figure 6 is a schematic diagram of the structure of a battery string according to an embodiment of the present application;

[0018] Figure 7 is a schematic structural diagram of a partial area of ​​a back contact battery according to an embodiment of the present application;

[0019] Figure 8 is a schematic structural diagram of a partial area of ​​a back contact battery according to an embodiment of the present application;

[0020] Fig. 9 A schematic structural diagram of a back contact battery according to an embodiment of the present application;

[0021] Fig.10 is a schematic structural diagram of a back contact battery according to an embodiment of the present application;

[0022] Description of main component symbols:

[0023] Battery string 100, back contact battery 10, silicon substrate 101, first pre-connection region 110, second pre-connection region 120, N-type doping region 1001, P-type doping region 1002, first electrical connector 21, second electrical connector 22;

[0024] The first sub-grid 11 , the first opposite-sex overlapping portion 111 , the first connecting portion 112 , the second opposite-sex overlapping portion 113 , the second connecting portion 114 , the second sub-grid 12 , the third opposite-sex overlapping portion 121 , the first extending portion 122 , the fourth opposite-sex overlapping portion 123 , the second extending portion 124 , the insulating member 30 , and the conductive grid 131 . DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals 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 present application, and should not be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0026] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", 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 application 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 should not be understood as a limitation on the present application.

[0027] 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 the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 this application can be understood according to specific circumstances.

[0029] In the present application, 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.

[0030] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the various specific processes and examples of materials provided by the present application, 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.

[0031] In the present application, since the resistivity of the silicon substrate is greater than or equal to 30Ω·cm, and the ratio of the total length of the first sub-gate connected to the N-type doped region to the total length of the second sub-gate connected to the P-type doped region in all sub-gate groups is 0.66-1.2, it can be ensured that in the back contact battery with a silicon substrate with a low doping concentration, the sum of the lengths of the P-type doped regions is large enough, thereby ensuring the effective collection of hole carriers.

[0032] Embodiment 1

[0033] See also Figure 1 , Figure 2 , Figure 3 , Figure 5 , Figure 6 and Figure 7 The back contact cell 10 of the embodiment of the present application comprises a silicon substrate 101, a plurality of first sub-grids 11 and a plurality of second sub-grids 12;

[0034] The first sub-gate 11 and the second sub-gate 12 are respectively connected to the N-type doping region 1001 and the P-type doping region 1002 of the silicon substrate 101 , and the resistivity of the silicon substrate of the silicon substrate 101 is greater than or equal to 30Ω·cm;

[0035] The first auxiliary grid 11 and the second auxiliary grid 12 extend along the first direction, are spaced from each other, and are arranged along the first direction to form a row of auxiliary grid groups; a plurality of rows of auxiliary grid groups are spaced from each other and are arranged in sequence along the second direction, and the second direction intersects the first direction;

[0036] In all the auxiliary grid groups, the ratio of the total length of the first auxiliary grid 11 to the total length of the second auxiliary grid 12 is 0.66-1.2.

[0037] The back contact cell 10 of the embodiment of the present application has a resistivity of the silicon substrate greater than or equal to 30Ω·cm, and the ratio of the total length of the first sub-gate 11 connected to the N-type doped region 1001 to the total length of the second sub-gate 12 connected to the P-type doped region 1002 in all sub-gate groups is 0.66-1.2. Therefore, it can be ensured that in the back contact cell 10 with a silicon substrate with a low doping concentration, the sum of the lengths of the P-type doped region 1002 is large enough, thereby ensuring the effective collection of hole carriers.

[0038] Specifically, the back contact cell 10 can be a sliced ​​cell formed by cutting a whole cell, such as Figure 1 As shown; the back contact battery 10 can be a whole battery that has not been cut. This is not limited here. The whole back contact battery 10 that has not been cut includes a slicing groove, and the whole battery can be cut along the slicing groove to obtain a sliced ​​battery. The whole back contact battery 10 that has not been cut can be asymmetrical or symmetrical along the slicing groove.

[0039] In addition, along the second direction, the auxiliary grid group may be asymmetrical, such as Figure 1 and Figure 5 Along the second direction, the auxiliary grid group may be asymmetrical, such as Figure 4 and Fig. 9 shown.

[0040] Specifically, the back contact cell 10 may be a busbar back contact cell 10 or a busbar-free back contact cell 10. Preferably, it is a busbar-free back contact cell 10. This article takes the busbar-free back contact cell 10 as an example for explanation and description.

[0041] Specifically, the silicon base 101 may include a silicon substrate, a first doping layer, a second doping layer, and a dielectric film layer.

[0042] Further, the silicon substrate may be a P-type silicon substrate, that is, the conductivity type of the entire region of the silicon substrate is P-type. The silicon substrate may also be an N-type silicon substrate, that is, the conductivity type of the entire region of the silicon substrate is N-type. The conductivity type of a portion of the silicon substrate may be N-type, and the conductivity type of the remaining region may be P-type. The silicon substrate may be a single crystal silicon substrate or a polycrystalline silicon substrate. The specific form of the silicon substrate is not limited herein.

[0043] Furthermore, the resistivity of the silicon substrate is greater than or equal to 30Ω·cm, for example, 30Ω·cm, 32Ω·cm, 40Ω·cm, 45Ω·cm, 50Ω·cm, or 100Ω·cm. The specific value of the resistivity of the silicon substrate is not limited here.

[0044] It can be understood that the resistivity of all regions of the silicon substrate is greater than or equal to 30Ω·cm. In the case where the conductivity type of a portion of the silicon substrate is N-type and the conductivity type of the remaining region is P-type, the resistivity of the region of the silicon substrate with the N-type conductivity type and the region of the silicon substrate with the P-type conductivity type are both greater than or equal to 30Ω·cm.

[0045] It can be understood that the resistivity of the silicon substrate at various locations may be the same, and may be a value greater than or equal to 30Ω·cm. The resistivity of the silicon substrate at various locations may also be different, but may be within a range greater than or equal to 30Ω·cm.

[0046] Furthermore, the doping concentration of the silicon substrate is less than or equal to 5×10 14 atoms / cm 3 For example, 5×10 14 atoms / cm 3 4.8×10 14 atoms / cm 3 , 4×10 14 atoms / cm 3 , 3.5×10 14 atoms / cm 3 , 2×10 14 atoms / cm 3 , 1×10 14 atoms / cm 3 , 0.5×10 14 atoms / cm 3 The specific value of the doping concentration of the silicon substrate is not limited here. In this way, the doping concentration of the silicon substrate is within a suitable range, which can ensure that the resistivity of the silicon substrate is greater than or equal to 30Ω·cm. It can be understood that the doping concentration is less than or equal to 5×10 14 atoms / cm 3 Silicon substrate, including a silicon substrate with a low doping concentration and an intrinsic silicon substrate.

[0047] It can be understood that the doping concentration of all regions of the silicon substrate is less than or equal to 5×10 14 atoms / cm 3 When the conductivity type of some regions of the silicon substrate is N-type and the conductivity type of the remaining regions is P-type, the doping concentration of the N-type region and the P-type region in the silicon substrate is less than or equal to 5×10 14 atoms / cm 3 .

[0048] It can be understood that the doping concentration of the silicon substrate can be the same everywhere, and is less than or equal to 5×10 14atoms / cm 3 The doping concentration of the silicon substrate can also be different, but it is less than or equal to 5×10 14 atoms / cm 3 within the range.

[0049] Furthermore, the first doped layer and the second doped layer are arranged on the silicon substrate. The first doped layer and the second doped layer have different doping polarities. The two doped layers can be formed by diffusion into the silicon substrate or by depositing a film layer on the silicon substrate.

[0050] It can be understood that in the thickness direction of the back contact battery 10, the first doped layer is stacked on the silicon substrate, and the second doped layer is stacked on the silicon substrate. On the plane perpendicular to the thickness direction of the back contact battery 10, the first doped layer and the second doped layer are distributed in different regions, corresponding to the N-type doped region 1001 and the P-type doped region 1002, respectively. Figure 3 and Figure 7 shown.

[0051] Furthermore, the dielectric film layer covers the first doped layer and the second doped layer, the first sub-gate 11 passes through the dielectric film layer to contact the first doped layer, and the second sub-gate 12 passes through the dielectric film layer to contact the second doped layer. In this way, the dielectric film layer is used to achieve electrical isolation of the first doped layer and the second doped layer, and the dielectric film layer can be used to reduce light reflection and recombination. The dielectric film layer is also provided between at least one pair of adjacent N-type doped regions 1001 and P-type doped regions 1002, and the dielectric film layer electrically isolates the N-type doped region 1001 and the P-type doped region 1002. Please note that in order to better display the N-type doped region 1001 and the P-type doped region 1002, Figure 3 and Figure 7 The portion of the dielectric film layer covering the N-type doping region 1001 and the P-type doping region 1002 is omitted.

[0052] Specifically, the first sub-gate 11 and the second sub-gate 12 may be distributed in the entire area of ​​the silicon substrate 101. Figure 1 , Figure 5 As shown, the first sub-gate 11 and the second sub-gate 12 may be distributed in a partial area of ​​the silicon substrate 101. For example, the first sub-gate 11 and the second sub-gate 12 are distributed in the right area of ​​the silicon substrate 101. It can be understood that the left area of ​​the silicon substrate 101 may be distributed with other sub-gates, may be distributed with a main gate, or may not be provided with a gate line.

[0053] Specifically, the first auxiliary gate 11 and the second auxiliary gate 12 have different polarities. The first auxiliary gate 11 corresponds to the first doping layer and the N-type doping region 1001 , and the second auxiliary gate 12 corresponds to the second doping layer and the P-type doping region 1002 .

[0054] Specifically, the first sub-gate 11 is connected to the N-type doping region 1001 of the silicon substrate 101 , and the second sub-gate 12 is connected to the P-type doping region 1002 of the silicon substrate 101 .

[0055] Specifically, the number of the first sub-grids 11 may be 1, 2, 3, 4 or other numbers. The number of the second sub-grids 12 may be 1, 2, 3, 4 or other numbers. No limitation is made here. The number of the first sub-grids 11 and the number of the second sub-grids 12 may be the same or different.

[0056] Specifically, the first auxiliary grid 11 extends along the first direction, which means that the overall extension direction of the first auxiliary grid 11 is the first direction. This does not represent a limitation on the specific form of the first auxiliary grid 11. In the present embodiment, the first auxiliary grid 11 is in a straight line shape, and the extension direction of the first auxiliary grid 11, that is, the first direction, is the length direction of the first auxiliary grid 11. In other embodiments, the first auxiliary grid 11 may also be in a wavy line shape, a broken line shape or other shapes. In addition, the shapes of several first auxiliary grids 11 may be the same or different. The second auxiliary grid 12 is similar to the first auxiliary grid 11, and reference may be made to the explanation and description of the first auxiliary grid 11 herein, which will not be repeated here to avoid redundancy.

[0057] Specifically, “the first sub-grid 11 and the second sub-grid 12 are spaced apart from each other” means that, along the first direction, a gap is formed between the adjacent first sub-grids 11 and second sub-grids 12. “The first sub-grid 11 and the second sub-grid 12 are arranged along the first direction” means that the gate lines arranged along the first direction include the first sub-grid 11 and the second sub-grid 12, rather than only one of the first sub-grid 11 and the second sub-grid 12. It can be understood that, along the first direction, the first sub-grid 11 and the second sub-grid 12 can be arranged alternately, such as Figure 1 As shown; it can also be arranged non-alternatingly, such as Figure 5 As shown. No limitation is made here. In this way, a row of sub-gate groups is formed in the first direction.

[0058] Furthermore, the sub-grids in a row of sub-grid groups have the same width, and the center lines along the first direction are located in the same straight line. In this way, the arrangement of the two sub-grids is more regular, which is convenient for improving the manufacturing efficiency and is also conducive to fully collecting carriers. It can be understood that in other embodiments, the sub-grids in a row of sub-grid groups may have different widths; it may also be that some of the sub-grids in a row of sub-grid groups are located in the same straight line along the center line of the first direction, and the remaining sub-grids are not located on the straight line along the center line of the first direction; it may also be that all the sub-grids in a row of sub-grid groups are not located in the same straight line along the center line of the first direction.

[0059] Furthermore, in a row of sub-gate groups, the spacings between adjacent sub-gates are the same. In this way, the arrangement of the two sub-gates is more regular, which is convenient for improving the manufacturing efficiency and is also conducive to fully collecting carriers. It can be understood that in other embodiments, the spacings between adjacent sub-gates in a row of sub-gate groups may be different; or the spacings between adjacent sub-gates in a row of sub-gate groups may be partially the same, and the remaining spacings are different from the same spacings.

[0060] Specifically, “a plurality of rows of sub-grid groups are spaced apart from each other and sequentially arranged along the second direction” means that a gap is formed between two adjacent rows of sub-grid groups, and a plurality of rows of sub-grid groups are sequentially arranged along the second direction.

[0061] Furthermore, the number of the auxiliary grid groups may be 1 row, 2 rows, 3 rows, 4 rows or other numbers, which are not limited here.

[0062] Furthermore, any pair of adjacent two rows of sub-grid groups have the same spacing. In this way, the arrangement of the sub-grid groups is more regular, which is convenient for improving the manufacturing efficiency and is also conducive to fully collecting carriers. It can be understood that in other embodiments, the spacing between some adjacent two rows of sub-grid groups may be the same, and the spacing between the remaining two adjacent rows of sub-grid groups may be different from the spacing; or any pair of adjacent two rows of sub-grid groups may have different spacings.

[0063] exist Figure 1 In the example, counting from top to bottom in the second direction, the first row of sub-grid groups, that is, the top row of sub-grid groups in the figure, are arranged in sequence from left to right in the first direction with spacing: second sub-grid 12, first sub-grid 11, second sub-grid 12, first sub-grid 11. The second row of sub-grid groups, that is, the sub-grid groups in the row below the first row of sub-grid groups, are arranged in sequence from left to right in the first direction with spacing: first sub-grid 11, second sub-grid 12, first sub-grid 11, second sub-grid 12. The third row of sub-grid groups, that is, the sub-grid groups in the row below the second row of sub-grid groups, are arranged in sequence from left to right in the first direction with spacing: second sub-grid 12, first sub-grid 11, second sub-grid 12, first sub-grid 11... and so on.

[0064] exist Figure 5In the example, counting from top to bottom in the second direction, the first row of sub-grid groups, i.e., the top row of sub-grid groups in the figure, are sequentially arranged from left to right in the first direction with spacing: second sub-grid 12, first sub-grid 11, second sub-grid 12, second sub-grid 12, first sub-grid 11. The second row of sub-grid groups, i.e., the sub-grid groups in the row below the first row of sub-grid groups, are sequentially arranged from left to right in the first direction with spacing: first sub-grid 11, second sub-grid 12, second sub-grid 12, first sub-grid 11, second sub-grid 12, second sub-grid 12. The third row of sub-grid groups, i.e., the sub-grid groups in the row below the second row of sub-grid groups, are sequentially arranged from left to right in the first direction with spacing: second sub-grid 12, first sub-grid 11, second sub-grid 12, second sub-grid 12, first sub-grid 11... and so on.

[0065] Specifically, the intersection of the first direction and the second direction means that the first direction and the second direction do not overlap, are not the same, and are not opposite. In this embodiment, the first direction and the second direction are perpendicular to each other. The first direction and the second direction are parallel to two adjacent long sides of the silicon substrate 101, respectively. It can be understood that in other embodiments, the first direction and the second direction may also be at an acute angle or an obtuse angle; the first direction and the second direction may also be at an acute angle or an obtuse angle to two adjacent long sides of the silicon substrate 101, respectively. This is not limited here. Please note that the "two adjacent long sides" here refer to the sides other than the corners of the silicon substrate 101, and the arc sides or short sides with rounded corners or chamfers at the corners of the silicon substrate 101 are not considered.

[0066] Specifically, "in all sub-grid groups, the ratio of the total length of the first sub-grids 11 to the total length of the second sub-grids 12 is 0.66-1.2" means that in all sub-grid groups, the ratio of the sum of the lengths of all first sub-grids 11 to the sum of the lengths of all second sub-grids 12 is 0.66-1.2. For example, 0.66, 0.67, 0.7, 0.8, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2.

[0067] It can be understood that the first sub-gate 11 and the second sub-gate 12 extend along the first direction, so the lengths of the first sub-gate 11 and the second sub-gate 12 are respectively the dimensions of the first sub-gate 11 and the second sub-gate 12 in the first direction.

[0068] See also Figure 2 and Figure 6It can be understood that the battery string 100 can be formed by electrically connecting two adjacent back-contact cells 10 using the first electrical connector 21 and the second electrical connector 22. Please note that the first electrical connector 21 and the second electrical connector 22 are respectively connected to two sub-grids of different polarities in one back-contact cell 10, namely the first sub-grid 11 and the second sub-grid 12. Therefore, the first electrical connector 21 and the second electrical connector 22 discussed below are all in the case of the same back-contact cell 10. For two adjacent back-contact cells 10, the first electrical connector 21 and the second electrical connector 22 are both connected to a sub-grid of one polarity in one back-contact cell 10 and a sub-grid of another polarity in another back-contact cell 10. Therefore, the explanation and description of the first electrical connector 21 and the second electrical connector 22 can refer to each other, and the explanation and description of the relationship between the two electrical connectors and the two sub-grids can also refer to each other.

[0069] Embodiment 2

[0070] In some embodiments, in the first direction, the secondary gates in a row of secondary gate groups located at the first end have opposite polarities to the secondary gates in an adjacent secondary gate group located at the first end.

[0071] In this way, carriers of two polarities can be better collected at the first end of the sub-gate group, which is beneficial to improving the photoelectric conversion efficiency.

[0072] See also Figure 1 In some embodiments, in the first direction, the secondary gates located at the second end of a row of secondary gate groups have opposite polarities to the secondary gates located at the second end of an adjacent secondary gate group.

[0073] In this way, carriers of two polarities can be better collected at the second end of the sub-gate group, which is beneficial to improving the photoelectric conversion efficiency.

[0074] It can be understood that the first end and the second end are two ends in the first direction respectively. Figure 1 In the example, the first end may be one of the left end and the right end, and the second end may be the other of the left end and the right end. That is, in two adjacent rows of auxiliary grid groups, the leftmost auxiliary grid has opposite polarity; the rightmost auxiliary grid has opposite polarity.

[0075] Embodiment 3

[0076] In some embodiments, in all the sub-grid groups, the ratio of the total length of the first sub-grid 11 to the total length of the second sub-grid 12 is 0.66-1, for example, 0.66, 0.68, 0.7, 0.8, 0.85, 0.9, 0.95, 0.99, or 1.

[0077] In this way, it is ensured that the total length of the first sub-gate 11 is less than or equal to the total length of the second sub-gate 12 , so that the distribution of the photoelectric conversion efficiency is more concentrated and close to the highest efficiency.

[0078] Embodiment 4

[0079] In some embodiments, in all the auxiliary grid groups, the ratio of the total length of the first auxiliary grid 11 to the total length of the second auxiliary grid 12 is 0.66-0.95, for example, 0.66, 0.67, 0.68, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95.

[0080] In this way, the range of the ratio of the total length of the first sub-gate 11 to the total length of the second sub-gate 12 is further optimized, so that the distribution of the photoelectric conversion efficiency is more concentrated and closer to the highest efficiency.

[0081] Embodiment 5

[0082] See also Figure 1 , Figure 2 , Figure 5 and Figure 6 , in some embodiments, three adjacent rows of sub-gate groups are respectively a first group, a second group and a third group;

[0083] The first sub-gate 11 in the first group includes a first opposite overlapping portion 111 and a first connecting portion 112 , and the first sub-gate 11 in the third group includes a second opposite overlapping portion 113 and a second connecting portion 114 . The corresponding first connecting portion 112 and second connecting portion 114 form a first pre-connection region 110 .

[0084] In this way, the first sub-grids 11 in the first and third groups respectively located on both sides of the second group form the first pre-connection area 110 through the connection parts, so that the first electrical connectors 21 can connect the corresponding first sub-grids 11 in alternate rows.

[0085] Specifically, “three adjacent rows of auxiliary grid groups are respectively the first group, the second group and the third group” means that among all auxiliary grid groups, there are three adjacent rows of auxiliary grid groups that satisfy the arrangement rules of the first group, the second group and the third group. Furthermore, any three adjacent rows of auxiliary grid groups satisfy the arrangement rules of the first group, the second group and the third group.

[0086] For the convenience of explanation, this paper uses Figure 1 Take as an example to illustrate, specifically, Figure 1 and Figure 2 The top three rows of sub-grid groups are taken as the first group, the second group and the third group for explanation. That is, counting from top to bottom in the second direction, the first row of sub-grid groups, that is, the top row of sub-grid groups in the figure, is taken as the first group; the second row of sub-grid groups, that is, the sub-grid groups in the next row of the first row of sub-grid groups, is taken as the second group; the third row of sub-grid groups, that is, the sub-grid groups in the next row of the second row of sub-grid groups, is taken as the third group. It can be understood that this is only an example and does not represent a limitation on the first group, the second group and the third group.

[0087] Specifically, the first sub-grid 11 in the first group includes a first heterosexual overlapping portion 111 and a first connecting portion 112. The first heterosexual overlapping portion 111 refers to a portion of the first sub-grid 11 of the first group that overlaps with the second sub-grid 12 of the second group in the second direction. The first connecting portion 112 refers to a portion of the first sub-grid 11 of the first group that is to be connected to the first sub-grid 11 of the third group through an electrical connector in the second direction. In other words, the first connecting portion 112 cannot be blocked by the insulating layer and needs to be exposed to be connected to the electrical connector. It can be understood that the first connecting portion 112 can overlap with the second sub-grid 12 in the second direction, such as Figure 1 As shown, it can also be staggered with the second auxiliary grid 12 in the second direction, such as Figure 5 shown.

[0088] Specifically, the first sub-grid 11 in the third group includes a second heterosexual overlapping portion 113 and a second connecting portion 114. The second heterosexual overlapping portion 113 refers to a portion of the first sub-grid 11 of the second group that overlaps with the second sub-grid 12 of the second group in the second direction. The second connecting portion 114 refers to a portion of the first sub-grid 11 of the second group that is to be connected to the first sub-grid 11 of the first group through an electrical connector in the second direction. In other words, the second connecting portion 114 cannot be blocked by the insulating layer and needs to be exposed to be connected to the electrical connector. It can be understood that the second connecting portion 114 can overlap with the second sub-grid 12 in the second direction, such as Figure 1 As shown, it can also be staggered with the second connecting portion 114 in the second direction, such as Figure 5 shown.

[0089] Specifically, “the corresponding first connection parts 112 and second connection parts 114 form the first pre-connection area 110” means that the first electrical connection member 21 can be arranged in the first pre-connection area 110 to connect the adjacent first connection parts 112 and second connection parts 114. In other words, the first pre-connection area 110 refers to the area where the first electrical connection member 21 is arranged. In other words, the first pre-connection area 110 is the area covered by the projection of the first electrical connection member 21 on the silicon substrate 101.

[0090] Please note that in two adjacent back-contact cells 10, the first electrical connector 21 connects the subgrid of one polarity in one back-contact cell 10, and connects the subgrid of another polarity in another back-contact cell 10. What is discussed here is the connection of the first electrical connector 21 in one back-contact cell 10. That is, in one back-contact cell 10, the first electrical connector 21 corresponds to the first subgrid 11, and corresponds to the first connection portion 112 and the second connection portion 114. It can be understood that in the adjacent back-contact cells 10 connected by the first electrical connector 21, the first electrical connector 21 corresponds to the second subgrid 12.

[0091] It can be understood that since the first electrical connector 21 is provided in the first pre-connection area 110 for connecting the adjacent first connection portion 112 and the second connection portion 114, in the back contact battery 10, as long as the adjacent first connection portion 112 and the second connection portion 114 exist, in the process of connecting two adjacent back contact batteries 10 to form a battery string 100, the first electrical connector 21 must be able to be provided in the first connection portion 112 and the second connection portion 114 to achieve connection, and the first pre-connection area 110 in the back contact battery 10 must be formed. Therefore, in the back contact battery 10, there is no need to limit, explain or illustrate the specific scope of the first pre-connection area 110.

[0092] Further, the first electrical connection member 21 includes at least one of a welding strip and a conductive wire. This article takes the first electrical connection member 21 as an example of a welding strip for description.

[0093] Specifically, the connection parts of the first electrical connector 21 and the first auxiliary grid 11, namely the first connection part 112 and the second connection part 114, can be electrically connected by at least one of conductive adhesive bonding, direct welding, solder paste welding, and physical contact, which is not limited here.

[0094] Please note that an insulating film may be provided on the side of the first electrical connector 21 facing the back contact battery 10. In the case where the first electrical connector 21 is provided with an insulating film, the size of the first electrical connector 21 in the first direction herein refers to the size of the portion without the insulating film, that is, the size of the first electrical connector 21 for effective electrical connection.

[0095] Embodiment 6

[0096] See also Figure 1 and Figure 2 In some embodiments, in the second group, at least one second sub-gate 12 extends into the first pre-connection region 110 .

[0097] In this way, the second sub-gate 12 does not need to avoid the first pre-connection area 110, and the first pre-connection area 110 can be used to further increase the length of the second sub-gate 12 connected to the P-type doping area 1002, thereby further ensuring that the total length of the corresponding P-type doping area 1002 is large enough to ensure the effective collection of holes, which is beneficial to improving the photoelectric conversion efficiency.

[0098] It can be understood that the portion of the second auxiliary grid 12 extending into the first pre-connection area 110 may be provided with an insulating member 30. In this way, the insulating member 30 can be used to electrically isolate the first electrical connection member 21 from the second auxiliary grid 12, thereby reducing the risk of short circuit.

[0099] Specifically, the second sub-gate 12 may cover a part or the whole of the first pre-connection region 110. The extent to which the second sub-gate 12 extends into the first pre-connection region 110 is not limited herein.

[0100] Specifically, in the second group, one, a plurality of or all of the second sub-gates 12 extend into the corresponding first pre-connection region 110 .

[0101] Embodiment 7

[0102] See also Figure 1 and Figure 2 In some embodiments, at least one second sub-gate 12 in the second group overlaps with one first sub-gate 11 in the first group in the second direction, passes through the first pre-connection region 110, and extends from both sides of the overlapping first sub-gate 11 to form two extension portions.

[0103] In this way, the first pre-connection area 110 can be used to increase the length of the second sub-gate 12 connected to the P-type doping area 1002 as much as possible. At the same time, two extensions are formed to further increase the length of the second sub-gate 12 connected to the P-type doping area 1002 outside the first pre-connection area 110, thereby further ensuring that the total length of the corresponding P-type doping area 1002 is large enough to ensure the effective collection of holes, which is beneficial to improving the photoelectric conversion efficiency.

[0104] Specifically, there may be one, two, three or other number of second sub-grids 12 in the second group, overlapping with one first sub-grid 11 in the first group in the second direction, penetrating the first pre-connection region 110, and extending from both sides of the overlapping first sub-grid 11 to form two extension portions, which are not limited here.

[0105] Specifically, the extension lengths of the two extension portions may be the same or different.

[0106] Embodiment 8

[0107] See also Figure 3 In some embodiments, two adjacent rows of auxiliary grid groups are respectively the first group and the second group; the second auxiliary grid 12 in the first group includes a third opposite-sex overlapping portion 121 and a first protruding portion 122, and the second auxiliary grid 12 in the second group includes a fourth opposite-sex overlapping portion 123 and a second protruding portion 124, and the adjacent first protruding portion 122 and second protruding portion 124 form a second pre-connection area 120; the first auxiliary grids 11 in the first group and the second group are disposed on both sides of the second pre-connection area 120.

[0108] In this way, since the adjacent first extensions 122 and second extensions 124 respectively located in two adjacent rows of sub-grid groups form the second pre-connection area 120, the electrical connector provided in the second pre-connection area 120 can be electrically connected to the extension of a sub-grid of corresponding polarity in each row of sub-grid groups, so that the electrical connector and the sub-grid have more connection points overall, and the overall connection tension between the back contact battery 10 and the electrical connector is increased. In addition, there is no need to set an insulating member 30 on the non-corresponding sub-grid, so the height of the electrical connector will not be raised by the insulating member 30, thereby reducing the risk of unstable connection between the back contact battery 10 and the electrical connector. Moreover, in this way, the electrical connector does not need to be electrically isolated from the non-corresponding sub-grid by the insulating member 30, which can reduce the risk of short circuit caused by partial loss or offset of the insulating member 30.

[0109] Specifically, the second sub-grid 12 in the first group includes a third opposite-sex overlapping portion 121 and a first protruding portion 122. The third opposite-sex overlapping portion 121 refers to a portion of the second sub-grid 12 of the first group that overlaps with the first sub-grid 11 of the second group in the second direction. The first protruding portion 122 refers to a portion of the second sub-grid 12 of the first group that does not overlap with the first sub-grid 11 of the second group in the second direction. In other words, the first protruding portion 122 refers to a portion of the second sub-grid 12 of the first group that protrudes from the first sub-grid 11 of the second group in the second direction.

[0110] Specifically, the second sub-grid 12 in the second group includes a fourth opposite-sex overlapping portion 123 and a second protruding portion 124. The fourth opposite-sex overlapping portion 123 refers to a portion of the second sub-grid 12 of the second group that overlaps with the first sub-grid 11 of the first group in the second direction. The second protruding portion 124 refers to a portion of the second sub-grid 12 of the second group that does not overlap with the first sub-grid 11 of the first group in the second direction. In other words, the second protruding portion 124 refers to a portion of the second sub-grid 12 of the second group that protrudes from the first sub-grid 11 of the first group in the second direction.

[0111] Specifically, “the first sub-gates 11 in the first group and the first sub-gates 11 in the second group are disposed on both sides of the second pre-connection region 120 ” means that the first sub-gates 11 in the first group and the first sub-gates 11 in the second group are adjacent to each other with respect to the second pre-connection region 120 .

[0112] Specifically, “the adjacent first extension 122 and the second extension 124 form the second pre-connection area 120” means that the second electrical connector 22 can be arranged in the second pre-connection area 120 to connect the adjacent first extension 122 and the second extension 124. In other words, the second pre-connection area 120 refers to the area where the second electrical connector 22 is arranged. In other words, the second pre-connection area 120 is the area covered by the projection of the second electrical connector 22 on the silicon substrate 101.

[0113] Specifically, the explanation and description of the first group and the second group, the explanation and description of the second pre-connection area 120, and the explanation and description of the second electrical connector 22 can be referred to the previous text, and will not be repeated here to avoid redundancy.

[0114] See also Figure 1 In some embodiments, the distance d1 between the endpoints of the adjacent first extension portion 122 and the second extension portion 124 in the first direction is -1 cm to 1 cm, for example -1 cm, -0.8 cm, -0.5 cm, -0.2 cm, 0 cm, 0.2 cm, 0.5 cm, 0.8 cm, 1 cm.

[0115] In this way, the distance d1 between the endpoints of the adjacent first extension portion 122 and the second extension portion 124 in the first direction is within an appropriate range, which can avoid the first extension portion 122 and the second extension portion 124 overlapping too much in the second direction due to a small distance, which is not conducive to collecting carriers of another polarity in the spacing area. It can also avoid the first extension portion 122 and the second extension portion 124 being too far apart in the first direction due to a large distance, which results in the required second electrical connector 22 being too wide and not conducive to collecting carriers in the spacing area.

[0116] Specifically, a distance d1 between the endpoints of the adjacent first extending portion 122 and the second extending portion 124 in the first direction may be referred to as a first distance d1 .

[0117] Please note that the first distance d1 is a negative number, which means that the adjacent first extension portions 122 and second extension portions 124 overlap in the second direction. Figure 1 As shown. The first spacing d1 is a positive number, which means that the adjacent first extension portion 122 and the second extension portion 124 do not overlap in the second direction, forming a gap. The first spacing d1 is 0, which means that the endpoints of the adjacent first extension portion 122 and the second extension portion 124 overlap in the second direction.

[0118] Please note that the back contact cell 10 may include multiple pairs of adjacent first extensions 122 and second extensions 124 to form multiple first spacings d1. All first spacings d1 may be the same, being a fixed value between -1 cm and 1 cm; or some first spacings d1 may be the same, while the rest of the first spacings d1 may be different; or all first spacings d1 may be different. In other words, in the back contact cell 10, multiple first spacings d1 may fluctuate within the range of -1 cm to 1 cm. This is not limited here.

[0119] See also Figure 1In some embodiments, the distance d1 between the endpoints of the adjacent first extension portion 122 and the second extension portion 124 in the first direction is -2 mm to 2 mm, for example -2 mm, -1.95 mm, -1.8 mm, -1.5 mm, -1.2 mm, -1 mm, -0.7 mm, -0.5 mm, -0.3 mm, 0 mm, 0.3 mm, 0.5 mm, 0.7 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 1.95 mm, 2 mm.

[0120] In this way, thinner second electrical connectors 22 can be adapted, and more groups of second electrical connectors 22 can be used when the total amount of second electrical connectors 22 is constant, so that the current transmission path is shorter and the effect of current extraction is better.

[0121] It can be understood that the smaller the absolute value of the distance d1 between the endpoints of the adjacent first extensions 122 and the second extensions 124 in the first direction, the smaller the overlap size or the interval size of the adjacent first extensions 122 and the second extensions 124, so the required size of the second electrical connector 22 in the first direction can be smaller. The length of the second electrical connector 22 remains substantially unchanged. When the total amount of the second electrical connector 22 is constant, the smaller the size of each second electrical connector 22 in the first direction, the more the number of the second electrical connectors 22 can be.

[0122] Specifically, when the second electrical connector 22 is a round welding strip, the size of the second electrical connector 22 in the first direction refers to the diameter of the round welding strip. When the second electrical connector 22 is a flat welding strip, the size of the second electrical connector 22 in the first direction refers to the width of the flat welding strip.

[0123] In some embodiments, the second electrical connector 22 includes a circular welding strip, and the distance d1 between the endpoints of the adjacent first extension 122 and the second extension 124 in the first direction is -2 mm to 2 mm, and the diameter of the corresponding circular welding strip is 0.2 mm to 3 mm. For example, 0.2 mm, 0.5 mm, 1 mm, 1.6 mm, 2 mm, 2.5 mm, 3 mm. Further, the diameter of the corresponding circular welding strip is preferably 0.2 mm to 0.35 mm. For example, 0.2 mm, 0.mm, 0.25 mm, 0.3 mm, 0.32 mm, 0.35 mm.

[0124] In some embodiments, the second electrical connector 22 includes a flat welding strip, and the distance d1 between the endpoints of the adjacent first extension 122 and the second extension 124 in the first direction is -2mm to 2mm, and the width of the corresponding flat welding strip is 0.6mm to 2.6mm. For example, 0.6mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 2mm, 2.3mm, 2.6mm. Further, the width of the corresponding flat welding strip is preferably 0.6mm to 1mm. For example, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm.

[0125] In some embodiments, the distance d1 between the endpoints of the adjacent first extension portion 122 and the second extension portion 124 in the first direction is -2 mm to 0 mm, for example -2 mm, -1.95 mm, 1.8 mm, -1.5 mm, -1.2 mm, -1 mm, -0.7 mm, -0.5 mm, -0.3 mm, or 0 mm.

[0126] In this way, the first extension 122 and the second extension 124 overlap, the total area connected with the electrical connector is larger, and the connection is more stable. At the same time, a thinner second electrical connector 22 can be adapted, and more groups of second electrical connectors 22 can be used when the total amount of second electrical connectors 22 is constant, so that the current transmission path is shorter and the effect of current extraction is better.

[0127] See also Fig.10 In some embodiments, the back contact cell 10 includes a conductive grid 131 , which has the same polarity as the second sub-grid 12 and connects the second sub-grids 12 in several rows of adjacent sub-grid groups.

[0128] Thus, when detecting reverse bias, the probe for detecting reverse bias can be placed at the intersection of the conductive grid 131 and the second auxiliary grid 12, which can increase the probability of the probe contacting the auxiliary grid and can more easily align the auxiliary grid, thereby facilitating the detection of reverse bias of the cell.

[0129] Specifically, the conductive grid 131 connects the second sub-grids 12 in 2 rows, 3 rows, 4 rows, or other numbers of adjacent sub-grid groups.

[0130] Specifically, the conductive grid 131 can connect the adjacent first extension 122 and second extension 124. In this way, the conductive grid 131 is more conveniently connected to the second auxiliary grid 12, without bypassing the first auxiliary grid 11, and without setting an insulating object between the conductive grid 131 and the first auxiliary grid 11, which can reduce the risk of conduction between the conductive grid 131 and the first auxiliary grid 11.

[0131] Furthermore, there are multiple conductive grids 131, and the multiple conductive grids 131 are connected to the same first extension 122 and second extension 124. In this way, the conductive grids 131, the first extension 122 and the second extension 124 form a grid, which further increases the probability of the probe contacting the secondary grid, and can more easily align the secondary grid.

[0132] See also Fig.10 In some embodiments, the conductive gate 131 includes at least one of a gate line and a pad. In other words, the conductive gate 131 includes one or all of a gate line and a pad.

[0133] In this way, the gate line serves as the conductive gate 131, and while increasing the probability of the probe contacting the sub-gate, it can strengthen the current collection in the silicon substrate 1011 region between the adjacent second sub-gates 12 in the second direction. The pad serves as the conductive gate 131, and while increasing the probability of the probe contacting the sub-gate, it can strengthen the current collection in the silicon substrate 101 region between the adjacent second sub-gates 12, and can further strengthen welding, reducing the risk of cold welding and desoldering.

[0134] Embodiment 9

[0135] See also Figure 1 In some embodiments, in the second group, the length of at least one second secondary gate 12 satisfies the following relationship:

[0136] 0.5X<S1-S2<1.95X;

[0137] Among them, S1 is the length of the second sub-gate 12 in the second group, S2 is the length of the corresponding first sub-gate 11 in the first group, and X is the spacing in the first direction between the first sub-gates 11 in the first and second groups respectively located on both sides of the second pre-connection area 120.

[0138] In this way, the difference between the length of at least one second sub-gate 12 in the second group and the length of the corresponding first sub-gate 11 in the first group is within an appropriate range, thereby enhancing the length of the second sub-gate 12 connected to the P-type doping region 1002, avoiding a short circuit caused by the excessive length of the second sub-gate 12, and avoiding the first sub-gate 11 connected to the N-type doping region 1001 being too short to affect the effect of the N-type doping region 1001 in collecting carriers, so that the back contact battery 10 has a better effect of collecting carriers as a whole.

[0139] Specifically, S1-S2 is, for example, 0.51X, 0.55X, 0.6X, 0.8X, 1X, 1.2X, 1.5X, 1.79X, 1.8X, 1.9X, 1.94X. The specific multiple relationship between S1-S2 and X is not limited here.

[0140] Preferably, 0.8X<S1-S2<1.5X. S1-S2 is, for example, 0.81X, 0.85X, 0.9X, 1X, 1.2X, 1.3X, 1.49X. In this way, the difference between the length of at least one second sub-grid 12 in the second group and the length of the corresponding first sub-grid 11 in the first group is further optimized, thereby further improving the overall effect of collecting carriers in the back contact battery 10.

[0141] Embodiment 10

[0142] See also Figure 5 and Figure 6 In some embodiments, in the second group, at least one second sub-gate 12 avoids the first pre-connection region 110 .

[0143] In this way, the second auxiliary grid 12 will not interfere with the first electrical connection member 21 provided in the first pre-connection area 110, and there is no need to electrically isolate the second auxiliary grid 12 from the first electrical connection member 21. The insulating member 30 can be omitted, which is beneficial to reducing costs and improving production efficiency.

[0144] Specifically, in the second group, one, a plurality of or all of the second sub-gates 12 avoid the first pre-connection region 110 .

[0145] Specifically, “the second sub-gate 12 avoids the first pre-connection area 110 ” means that the second sub-gate 12 has no overlapping portion with the first pre-connection area 110 , and the second sub-gate 12 is located outside the first pre-connection area 110 .

[0146] Embodiment 11

[0147] See also Figure 5 and Figure 6 In some embodiments, in the second group, two second sub-gates 12 located on both sides of the first pre-connection area 110 overlap with the first sub-gate 11 in the first group in the second direction, and extend from both sides of the overlapped first sub-gate 11 to form two extension portions respectively.

[0148] In this way, the length of the second sub-gate 12 connected to the P-type doped region 1002 can be further increased outside the first pre-connection region 110, thereby ensuring that the total length of the corresponding P-type doped region 1002 is large enough to ensure effective collection of holes, which is beneficial to improving photoelectric conversion efficiency.

[0149] Specifically, the extension lengths of the two extension portions may be the same or different.

[0150] Embodiment 12

[0151] See also Figure 5 and Figure 6In some embodiments, the second sub-grid 12 in the first group includes a third opposite-sex overlapping portion 121 and a first protruding portion 122, the second sub-grid 12 in the second group includes a fourth opposite-sex overlapping portion 123 and a second protruding portion 124, and the adjacent first protruding portion 122 and second protruding portion 124 form a second pre-connection area 120; the first sub-grids 11 in the first group and the second group are disposed on both sides of the second pre-connection area 120.

[0152] Please note that the explanation and description of this part can be found in the previous text. To avoid redundancy, it will not be repeated here.

[0153] Embodiment 13

[0154] See also Figure 5 and Figure 6 In some embodiments, in the second group, the length of at least one second secondary gate 12 satisfies the following relationship:

[0155] 0.5XD<S3+S4-S2<1.95XD;

[0156] Among them, S3 and S4 are respectively the lengths of the two second sub-gates 12 located on both sides of the first pre-connection area 110 in the second group, S2 is the length of the corresponding first sub-gate 11 in the first group, X is the spacing in the first direction between the two first sub-gates 11 located on both sides of the second pre-connection area 120 in the first group and the second group, and D is the spacing between the two second sub-gates 12 located on both sides of the first pre-connection area 110.

[0157] In this way, the difference between the sum of the lengths of the two second sub-gates 12 located on both sides of the first pre-connection area 110 in the second group and the length of the corresponding first sub-gate 11 in the first group is in an appropriate range, thereby enhancing the length of the second sub-gate 12 connected to the P-type doping area 1002, avoiding a short circuit caused by the excessive length of the second sub-gate 12, and avoiding the first sub-gate 11 connected to the N-type doping area 1001 being too short to affect the effect of collecting carriers in the N-type doping area, so that the back contact battery 10 has a better effect of collecting carriers as a whole.

[0158] Specifically, S3+S4-S2 is, for example, 0.51XD, 0.55XD, 0.6XD, 0.8XD, 1X-D, 1.2XD, 1.5XD, 1.79XD, 1.8XD, 1.9XD, and 1.94XD. The specific numerical relationship between S3+S4-S2 and X is not limited here.

[0159] Preferably, 0.8XD<S3+S4-S2<1.5XD. S1-S2 is, for example, 0.81XD, 0.85XD, 0.9XD, 1X-D, 1.2XD, 1.3XD, 1.49XD. In this way, the difference between the sum of the lengths of the two second sub-grids 12 located on both sides of the first pre-connection region 110 in the second group and the length of the corresponding first sub-grid 11 in the first group is further optimized, thereby further improving the overall effect of collecting carriers in the back contact battery 10.

[0160] Embodiment 14

[0161] See also Figure 3 and Figure 7 In some embodiments, the silicon substrate 101 includes a plurality of N-type doping regions 1001 and a plurality of P-type doping regions 1002 , the first sub-gate 11 is disposed on the N-type doping region 1001 , and the second sub-gate 12 is disposed on the P-type doping region 1002 ;

[0162] The N-type doping region 1001 and the P-type doping region 1002 extend along a first direction, and the N-type doping region 1001 and the P-type doping region 1002 are arranged along the first direction to form a row of doping region groups, and a plurality of rows of doping region groups are sequentially arranged along a second direction;

[0163] In all the doping region groups, the ratio of the total area of ​​the N-type doping region 1001 to the total area of ​​the P-type doping region 1002 is 0.66-1.2.

[0164] In this way, it can be ensured that the total area of ​​the P-type doping region 1002 in the back contact cell 10 with a silicon substrate having a low doping concentration is large enough, so that the hole carriers can be effectively collected. Moreover, the arrangement of the doping regions of two polarities and the sub-grids of two polarities is similar, which facilitates the manufacture of the sub-grids of the corresponding polarity on the doping regions and the electrical connection between the doping regions and the sub-grids of the corresponding polarity, which is conducive to reducing the process difficulty, improving the manufacturing efficiency and reducing the cost.

[0165] Specifically, “in all doping region groups, the ratio of the total area of ​​the N-type doping region 1001 to the total area of ​​the P-type doping region 1002 is 0.66-1.2” means that in all doping region groups, the ratio of the sum of the areas of all the P-type doping regions 1002 to the sum of the areas of all the N-type doping regions 1001 is 0.66-1.2. For example, 0.66, 0.67, 0.7, 0.8, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2.

[0166] Specifically, the N-type doping region 1001 and the P-type doping region 1002 can be formed in the entire area of ​​the silicon substrate 101, so that the first sub-gate 11 and the second sub-gate 12 are distributed in the entire area of ​​the silicon substrate 101; the N-type doping region 1001 and the P-type doping region 1002 can be formed in a partial area of ​​the silicon substrate 101, so that the first sub-gate 11 and the second sub-gate 12 are distributed in a partial area of ​​the silicon substrate 101.

[0167] Specifically, the polarities of the N-type doping region 1001 and the P-type doping region 1002 are different. The N-type doping region 1001 corresponds to the first doping layer, and the P-type doping region 1002 corresponds to the second doping layer.

[0168] Specifically, the number of N-type doping regions 1001 may be 1, 2, 3, 4 or other numbers. The number of P-type doping regions 1002 may be 1, 2, 3, 4 or other numbers. This is not limited here. The number of N-type doping regions 1001 and the number of P-type doping regions 1002 may be the same or different.

[0169] Specifically, the N-type doping region 1001 extends along the first direction, which means that the overall extension direction of the N-type doping region 1001 is the first direction. This does not represent a limitation on the specific form of the N-type doping region 1001. In the present embodiment, the N-type doping region 1001 is in a straight line shape, and the extension direction of the N-type doping region 1001, that is, the first direction, is the length direction of the N-type doping region 1001. In other embodiments, the N-type doping region 1001 may also be in a wavy line shape, a broken line shape, or other shapes. In addition, the shapes of several N-type doping regions 1001 may be the same or different. The explanation and description of the P-type doping region 1002 are similar to those of the N-type doping region 1001, and can be referenced to each other. To avoid redundancy, they will not be repeated here.

[0170] Specifically, “the N-type doping region 1001 and the P-type doping region 1002 are arranged along the first direction” means that the doping regions arranged along the first direction include the N-type doping region 1001 and the P-type doping region 1002, rather than only one of the N-type doping region 1001 and the P-type doping region 1002. It can be understood that along the first direction, the N-type doping region 1001 and the P-type doping region 1002 can be arranged alternately, such as Figure 1 As shown; it can also be arranged non-alternatingly, such as Figure 5 As shown. No limitation is made here. In this way, a row of sub-gate groups is formed in the first direction.

[0171] Further, in the case where a gap is formed between adjacent N-type doping regions 1001 and P-type doping regions 1002 or other film structures are provided, in a row of doping region groups, the spacing between adjacent N-type doping regions 1001 and P-type doping regions 1002 is the same. In this way, the arrangement of the two doping regions is more regular, which is convenient for improving the manufacturing efficiency and is also conducive to fully collecting carriers. It can be understood that in other embodiments, the spacing between adjacent N-type doping regions 1001 and P-type doping regions 1002 in a row of doping region groups may be different.

[0172] Specifically, the number of the doping region groups may be 1 row, 2 rows, 3 rows, 4 rows or other numbers, which are not limited here.

[0173] Furthermore, a gap may be formed between any pair of adjacent rows of doping region groups, the two groups may contact each other, or other film layer structures may be provided.

[0174] Furthermore, in the case where a gap can be formed between two adjacent rows of doped region groups or other film layer structures are provided, the spacing between the two adjacent rows of doped region groups is the same. In this way, the arrangement of the doped region groups is more regular, which is convenient for improving the manufacturing efficiency and is also conducive to fully collecting carriers. It can be understood that in other embodiments, the spacing between some adjacent rows of doped region groups can be the same, and the spacing between the remaining adjacent rows of doped region groups can be different from the spacing; it can also be that the spacing between any pair of adjacent rows of doped region groups is different.

[0175] In some embodiments, a dielectric film layer is disposed between at least one pair of adjacent N-type doping regions 1001 and P-type doping regions 1002 , and the dielectric film layer electrically isolates the N-type doping regions 1001 and the P-type doping regions 1002 .

[0176] In this way, the dielectric film layer is used to achieve electrical isolation between the first doped layer and the second doped layer, and the refractive index difference and surface passivation effect of the dielectric film layer can be used to reduce optical loss and carrier recombination.

[0177] Specifically, the dielectric film layer may be disposed between a pair of adjacent N-type doping regions 1001 and P-type doping regions 1002, or between multiple pairs of adjacent N-type doping regions 1001 and P-type doping regions 1002. In this embodiment, the dielectric film layer is disposed between all adjacent N-type doping regions 1001 and P-type doping regions 1002.

[0178] Specifically, the dielectric film layer covers the first doping layer and the second doping layer, the first auxiliary gate 11 passes through the dielectric film layer to contact the first doping layer, and the second auxiliary gate 12 passes through the dielectric film layer to contact the second doping layer. In order to better show the N-type doping region 1001 and the P-type doping region 1002, the portion of the dielectric film layer covering the N-type doping region 1001 and the P-type doping region 1002 is omitted in the figure.

[0179] Specifically, the dielectric film layer includes at least one of an aluminum oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbide layer, an amorphous silicon layer, and a silicon oxide layer.

[0180] In some embodiments, a trench is formed between the N-type doping region 1001 and the P-type doping region 1002 , and the dielectric film layer is at least partially disposed in the trench.

[0181] In this way, the trench can be used to electrically isolate the N-type doping region 1001 from the P-type doping region 1002 inside the silicon substrate 101 , thereby reducing the risk of conduction between the N-type doping region 1001 and the P-type doping region 1002 .

[0182] Specifically, “the dielectric film layer is at least partially disposed in the trench” means that a portion of the dielectric film layer is disposed in the trench and the remaining portion is disposed outside the trench, or the entire dielectric film layer is disposed in the trench.

[0183] Specifically, the trench is continuously provided between the N-type doping region 1001 and the P-type doping region 1002. In other words, the N-type doping region 1001 and the P-type doping region 1002 are separated by the trench. In this way, it is ensured that the N-type doping region 1001 and the P-type doping region 1002 cannot be conductively connected across the trench.

[0184] In some embodiments, in the first direction, a tunneling layer is disposed between at least one pair of adjacent N-type doping regions 1001 and P-type doping regions 1002 , and both the N-type doping regions 1001 and the P-type doping regions 1002 are in contact with the tunneling layer.

[0185] In this way, the reverse bias voltage can be reduced, and the heat generation power when the back contact cell 10 is shielded in the assembly and becomes a load can be reduced. In addition, the tunneling layer can play a passivation role, reducing the recombination at the junction of the N-type doped region 1001 and the P-type doped region 1002 in the first direction.

[0186] Specifically, the tunneling layer includes at least one of a silicon oxide layer, an aluminum oxide layer, and a silicon carbide layer.

[0187] Specifically, the tunneling layer may be disposed in the entire region of the boundary between adjacent N-type doping regions 1001 and P-type doping regions 1002 in the first direction, or in a partial region of the boundary between adjacent N-type doping regions 1001 and P-type doping regions 1002 in the first direction.

[0188] Specifically, a tunneling layer may be provided between all adjacent N-type doping regions 1001 and P-type doping regions 1002 in the first direction. It is understood that in other embodiments, a tunneling layer may be provided between one or more pairs of adjacent N-type doping regions 1001 and P-type doping regions 1002 in the first direction.

[0189] Specifically, in the second direction, a tunneling layer is disposed between at least one pair of adjacent N-type doping regions 1001 and P-type doping regions 1002 , and both the N-type doping regions 1001 and the P-type doping regions 1002 are in contact with the tunneling layer.

[0190] In this way, the reverse bias voltage can be reduced, and the heat generation power when the back contact cell 10 is shielded in the assembly and becomes a load can be reduced. In addition, the tunneling layer can play a passivation role, reducing the recombination at the junction of the N-type doped region 1001 and the P-type doped region 1002 in the second direction.

[0191] Specifically, the tunneling layer may be disposed in the entire region of the boundary between adjacent N-type doping regions 1001 and P-type doping regions 1002 in the second direction, or in a partial region of the boundary between adjacent N-type doping regions 1001 and P-type doping regions 1002 in the second direction.

[0192] Specifically, a tunneling layer may be provided between all adjacent N-type doping regions 1001 and P-type doping regions 1002 in the second direction. It is understood that in other embodiments, a tunneling layer may be provided between one or more pairs of adjacent N-type doping regions 1001 and P-type doping regions 1002 in the second direction.

[0193] In some embodiments, in the first direction, at least one pair of adjacent N-type doping regions 1001 and P-type doping regions 1002 are in contact with each other.

[0194] In this way, the reverse bias voltage can be reduced, and the heat generation power when the back contact battery 10 becomes a load after being shielded in the component can be reduced.

[0195] Specifically, the adjacent N-type doping regions 1001 and P-type doping regions 1002 may contact each other in the entire region of the adjacent regions in the first direction, or may contact each other in a partial region of the adjacent regions in the first direction.

[0196] In some embodiments, in the second direction, at least one pair of adjacent N-type doping regions 1001 and P-type doping regions 1002 are in contact with each other. The explanations and descriptions here can refer to the above text, and will not be repeated here to avoid redundancy.

[0197] In some embodiments, the first extending portion 122 and the second extending portion 124 are disposed on the P-type doping region 1002 , and the P-type doping region 1002 is continuously disposed between the first extending portion 122 and the second extending portion 124 .

[0198] In this way, carriers of corresponding polarity can be better collected between the first extension portion 122 and the second extension portion 124. At the same time, the risk of the second electrical connection member 22 disposed in the second pre-connection region 120 contacting with the oppositely doped region can be reduced.

[0199] Moreover, in this way, the structure required for electrical isolation, such as a groove, can be omitted between the first protruding portion 122 and the second protruding portion 124, thereby increasing the passivation contact area, which is beneficial to improving the photoelectric conversion efficiency.

[0200] Specifically, the P-type doping region 1002 covers and exceeds the second pre-connection region 120. In other words, the second pre-connection region 120 is located in the P-type doping region 1002. In this way, the risk of the second electrical connection member 22 provided in the second pre-connection region 120 contacting with the opposite doping region is minimized, and carriers of corresponding polarity can be better collected.

[0201] Embodiment 15

[0202] In some embodiments, in all doping region groups, the ratio of the total area of ​​the N-type doping region 1001 to the total area of ​​the P-type doping region 1002 is 0.66-1, for example, 0.66, 0.68, 0.7, 0.8, 0.85, 0.9, 0.95, 0.99, or 1.

[0203] In this way, the total area of ​​the N-type doping region 1001 is ensured to be less than or equal to the total area of ​​the P-type doping region 1002 , so that the photoelectric conversion efficiency distribution is more concentrated and close to the highest efficiency.

[0204] Embodiment 16

[0205] In some embodiments, in all the doping region groups, the ratio of the total area of ​​the N-type doping region 1001 to the total area of ​​the P-type doping region 1002 is 0.66-0.95, for example, 0.66, 0.67, 0.68, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95.

[0206] In this way, the range of the ratio of the total area of ​​the N-type doping region 1001 to the total area of ​​the P-type doping region 1002 is further optimized, so that the distribution of the photoelectric conversion efficiency is more concentrated and closer to the highest efficiency.

[0207] Embodiment 17

[0208] In some embodiments, three adjacent rows of doped region groups are respectively a first region group, a second region group, and a third region group;

[0209] The N-type doped region 1001 in the first region group includes a first heterosexual overlapping region and a first connection region, and the N-type doped region 1001 in the third region group includes a second heterosexual overlapping region and a second connection region. The adjacent first connection region and the second connection region form a first pre-connection region 110 .

[0210] In this way, the N-type doped regions 1001 in the first and third regional groups located on both sides of the second regional group form the first pre-connection region 110 through the connection region, so that the first electrical connector 21 connects the connection region of the N-type doped region 1001 through the corresponding first sub-gate 11 in alternate rows.

[0211] It can be understood that since the first sub-gate 11 is disposed in the N-type doping region 1001, the explanation and description of the N-type doping region 1001 can refer to the explanation and description of the first sub-gate 11, and will not be repeated here to avoid redundancy. For example, the first region group, the second region group, and the third region group correspond to the first group, the second group, and the third group in the foregoing text respectively; the first opposite-sex overlap region and the first connection region correspond to the first opposite-sex overlap portion 111 and the first connection portion 112 in the foregoing text respectively; the second opposite-sex overlap region and the second connection region correspond to the second opposite-sex overlap portion 113 and the second connection portion 114 in the foregoing text respectively.

[0212] Embodiment 18

[0213] See also Figure 1 , Figure 2 and Figure 3 ,as well as Figure 5 , Figure 6 and Figure 7 In some embodiments, in the second region group, the P-type doped region 1002 extends into the first pre-connection region 110 .

[0214] In this way, the P-type doping region 1002 does not need to avoid the first pre-connection region 110, and the first pre-connection region 110 can be used to further increase the length and area of ​​the P-type doping region 1002, thereby ensuring that the total length of the corresponding P-type doping region 1002 is large enough to ensure effective collection of holes, which is beneficial to improving the photoelectric conversion efficiency.

[0215] It can be understood that since the second sub-gate 12 is disposed in the P-type doping region 1002 , the explanation and description of the P-type doping region 1002 may refer to the explanation and description of the second sub-gate 12 , and will not be repeated here to avoid redundancy.

[0216] Embodiment 19

[0217] See also Figure 1 , Figure 2 and Figure 3 ,as well as Figure 5 , Figure 6 and Figure 7 In some embodiments, at least one P-type doping region 1002 in the second region group overlaps with an N-type doping region 1001 in the first region group in the second direction, penetrates the first pre-connection region 110, and extends from both sides of the overlapping N-type doping region 1001 to form two extending regions.

[0218] In this way, the first pre-connection area 110 can be used to increase the length of the P-type doping area 1002 of the corresponding P-type doping area as much as possible. At the same time, two extension areas are formed to further increase the length of the P-type doping area 1002 outside the first pre-connection area 110, thereby ensuring that the total length of the corresponding P-type doping area 1002 is large enough to ensure the effective collection of holes, which is beneficial to improving the photoelectric conversion efficiency.

[0219] As mentioned above, the explanation and description of this part can be found in the previous text. To avoid redundancy, it will not be repeated here.

[0220] Embodiment 20

[0221] See also Figure 1 , Figure 2 and Figure 3 ,as well as Figure 5 , Figure 6 and Figure 7 In some embodiments, the P-type doped region 1002 in the first regional group includes a third heterosexual overlapping region and a first extending region, the P-type doped region 1002 in the second regional group includes a fourth heterosexual overlapping region and a second extending region, and the adjacent first extending region and the second extending region form a second pre-connection region 120; the second pre-connection region 120 is provided with N-type doped regions 1001 in the first regional group and the second regional group on both sides.

[0222] In this way, the second sub-grid 12 can be set to the first extension area and the second extension area, so that the electrical connector set in the second pre-connection area 120 is electrically connected to the extension part of a sub-grid of corresponding polarity in each row of the sub-grid group, so that the electrical connector and the sub-grid have more connection points overall, and the overall connection tension between the back contact battery 10 and the electrical connector is increased. In addition, there is no need to set the insulating member 30 on the non-corresponding sub-grid, so the height of the electrical connector will not be raised by the insulating member 30, thereby reducing the risk of unstable connection between the back contact battery 10 and the electrical connector. Moreover, in this way, the electrical connector does not need to be electrically isolated from the non-corresponding sub-grid by the insulating member 30, which can reduce the risk of short circuit caused by partial loss or offset of the insulating member 30.

[0223] As mentioned above, the explanation and description of this part can be found in the previous text. To avoid redundancy, it will not be repeated here.

[0224] Embodiment 21

[0225] See also Figure 1 , Figure 2 and Figure 3 ,as well as Figure 5 , Figure 6 and Figure 7 In some embodiments, in the second region group, the length of at least one P-type doping region 1002 satisfies the following relationship:

[0226] 0.5x<s1-s2<1.95x;

[0227] Among them, s1 is the length of the P-type doping region 1002 in the second regional group, s2 is the length of the corresponding N-type doping region 1001 in the first regional group, and x is the distance in the first direction between the two N-type doping regions 1001 located on both sides of the second pre-connection region 120 in the first regional group and the second regional group.

[0228] In this way, the difference between the length of at least one P-type doping region 1002 in the second area group and the length of the corresponding N-type doping region 1001 in the first area group is within an appropriate range, thereby enhancing the length of the P-type doping region 1002 connected to the P-type doping region, avoiding a short circuit caused by the excessive length of the P-type doping region 1002, and avoiding the N-type doping region 1001 connected to the N-type doping region being too short to affect the effect of the N-type doping region in collecting carriers, so that the back contact battery 10 has a better effect in collecting carriers as a whole.

[0229] Specifically, s1-s2 is, for example, 0.51x, 0.55x, 0.6x, 0.8x, 1x, 1.2x, 1.5x, 1.79x, 1.8x, 1.9x, and 1.94x. The specific multiple relationship between s1-s2 and x is not limited here.

[0230] Preferably, 0.8x<s1-s2<1.5x. s1-s2 is, for example, 0.81x, 0.85x, 0.9x, 1x, 1.2x, 1.3x, 1.49x. In this way, the difference between the length of at least one P-type doping region 1002 in the second region group and the length of the corresponding N-type doping region 1001 in the first region group is further optimized, thereby further improving the effect of collecting carriers on the back contact cell 10 as a whole.

[0231] Embodiment 22

[0232] See also Figure 5 , Figure 6 and Figure 8 In some embodiments, in the second region group, the P-type doped region 1002 avoids the first pre-connection region 110 .

[0233] In this way, the P-type doped region 1002 will not interfere with the first electrical connector 21 provided in the first pre-connection region 110, and there is no need to electrically isolate the P-type doped region 1002 from the first electrical connector 21. The insulating member 30 can be omitted, which is beneficial to reducing costs and improving production efficiency.

[0234] As mentioned above, the explanation and description of this part can be found in the previous text. To avoid redundancy, it will not be repeated here.

[0235] Embodiment 23

[0236] See also Figure 5 , Figure 6 and Figure 8 In some embodiments, in the second region group, two P-type doping regions 1002 located on both sides of the first pre-connection region 110 overlap with the N-type doping region 1001 in the first region group in the second direction, and extend from both sides of the overlapping N-type doping region 1001 to form two extending regions respectively.

[0237] In this way, the length of the P-type doping region 1002 corresponding to the first pre-connection region 110 can be further increased, thereby further ensuring that the total length of the corresponding P-type doping region 1002 is large enough to ensure effective collection of carriers, which is beneficial to improving photoelectric conversion efficiency.

[0238] As mentioned above, the explanation and description of this part can be found in the previous text. To avoid redundancy, it will not be repeated here.

[0239] Embodiment 24

[0240] See also Figure 5 , Figure 6 and Figure 8 In some embodiments, the P-type doping region 1002 in the first region group includes a third heterosexual overlapping region and a first protruding region, the P-type doping region 1002 in the second region group includes a fourth heterosexual overlapping region and a second protruding region, and the adjacent first protruding region and the second protruding region form a second pre-connection region 120;

[0241] N-type doping regions 1001 in the first region group and the second region group are disposed on both sides of the second pre-connection region 120 .

[0242] Please note that the explanation and description of this part can be found in the previous text. To avoid redundancy, it will not be repeated here.

[0243] Embodiment 25

[0244] See also Figure 5 , Figure 6 and Figure 8 In some embodiments, in the second region group, the length of at least one P-type doping region 1002 satisfies the following relationship:

[0245] 0.5xd<s3+s4-s2<1.95xd;

[0246] Among them, s3 and s4 are respectively the lengths of the two P-type doping regions 1002 located on both sides of the first pre-connection region 110 in the second regional group, s2 is the length of the corresponding N-type doping region 1001 in the first regional group, x is the distance in the first direction between the two N-type doping regions 1001 located on both sides of the second pre-connection region 120 in the first regional group and the second regional group, and d is the distance between the two P-type doping regions 1002 located on both sides of the first pre-connection region 110.

[0247] In this way, the difference between the sum of the lengths of the two P-type doping regions 1002 located on both sides of the first pre-connection region 110 in the second regional group and the length of the corresponding N-type doping region 1001 in the first regional group is in an appropriate range, thereby enhancing the length of the P-type doping region 1002 corresponding to the P-type doping region, avoiding a short circuit caused by the excessive length of the P-type doping region 1002, and avoiding the N-type doping region 1001 corresponding to the N-type doping region being too short to affect the effect of the N-type doping region in collecting carriers, so that the back contact battery 10 has a better effect in collecting carriers as a whole.

[0248] Specifically, s3+s4-s2 is, for example, 0.51xd, 0.55xd, 0.6xd, 0.8xd, 1x-d, 1.2xd, 1.5xd, 1.79xd, 1.8xd, 1.9xd, and 1.94xd. The specific numerical relationship between s3+s4-s2 and x is not limited here.

[0249] Preferably, 0.8xd<s3+s4-s2<1.5xd. S1-S2 is, for example, 0.81xd, 0.85xd, 0.9xd, 1x-d, 1.2xd, 1.3xd, 1.49xd. In this way, the difference between the sum of the lengths of the two P-type doping regions 1002 located on both sides of the first pre-connection region 110 in the second regional group and the length of the corresponding N-type doping region 1001 in the first group is further optimized, thereby further improving the effect of collecting carriers on the back contact battery 10 as a whole.

[0250] The battery in the related art is used as a comparative example and compared with the back contact battery 10 of the present application.

[0251] A battery in the related art is used as comparative example 1. The silicon substrate of the battery is P-type. The total length of the two polarity auxiliary grids is equal, and the ratio is 1. The open circuit voltage is 0.729V and the short circuit current density is 42.6mA / cm 2 , the filling factor is 0.841 and the conversion efficiency is 26.12%.

[0252] Another battery in the related art is used as comparative example 2. The silicon substrate of the battery is N-type. The total length of the two polarity auxiliary grids is equal, and the ratio is 1. The open circuit voltage is 0.736V and the short circuit current density is 42.7mA / cm 2 , the filling factor is 0.842 and the conversion efficiency is 26.46%.

[0253] In an example of the back contact battery 10 of the present application, the silicon substrate is N-type, and the resistivity of the silicon substrate is greater than or equal to 30Ω·cm. In all the auxiliary grid groups, the ratio of the total length of the first auxiliary grid 11 to the total length of the second auxiliary grid 12 is 0.66. The open circuit voltage is 0.747V, and the short circuit current density is 42.8mA / cm 2 , the filling factor is 0.848 and the conversion efficiency is 27.11%.

[0254] In an example of the back contact battery 10 of the present application, the silicon substrate is N-type, and the resistivity of the silicon substrate is greater than or equal to 30Ω·cm. In all the auxiliary grid groups, the ratio of the total length of the first auxiliary grid 11 to the total length of the second auxiliary grid 12 is 0.95. The open circuit voltage is 0.741V, and the short circuit current density is 42.9mA / cm 2 , the filling factor is 0.851 and the conversion efficiency is 27.05%.

[0255] In an example of the back contact battery 10 of the present application, the silicon substrate is N-type, and the resistivity of the silicon substrate is greater than or equal to 30Ω·cm. In all the auxiliary grid groups, the ratio of the total length of the first auxiliary grid 11 to the total length of the second auxiliary grid 12 is 1.2. The open circuit voltage is 0.742V, and the short circuit current density is 43mA / cm 2 , the filling factor is 0.842 and the conversion efficiency is 26.86%.

[0256] In an example of the back contact battery 10 of the present application, the silicon substrate is of P type, and the resistivity of the silicon substrate is greater than or equal to 30Ω·cm. In all the auxiliary grid groups, the ratio of the total length of the first auxiliary grid 11 to the total length of the second auxiliary grid 12 is 1. The open circuit voltage is 0.74V, and the short circuit current density is 42.6mA / cm 2 , the filling factor is 0.851 and the conversion efficiency is 26.83%.

[0257] Obviously, compared with the battery in the related art, the back contact battery 10 of the embodiment of the present application has a higher open circuit voltage, a higher or equal short circuit current, a higher fill factor, and a significantly improved conversion efficiency.

[0258] Embodiment 26

[0259] See also Figure 2The battery assembly of the embodiment of the present application includes a plurality of electrical connectors and a plurality of back-contact batteries 10 of any one of Embodiments 1 to 21, wherein the electrical connectors connect a first sub-grid 11 of a back-contact battery 10 and a second sub-grid 12 of an adjacent back-contact battery 10.

[0260] In the battery assembly of the embodiment of the present application, since the resistivity of the silicon substrate in the back-contact battery 10 is greater than or equal to 30Ω·cm, and the ratio of the total length of the first sub-gate 11 connected to the N-type doped region 1001 to the total length of the second sub-gate 12 connected to the P-type doped region 1002 in all the sub-gate groups is 0.66-1.2, it can be ensured that in the back-contact battery 10 with a silicon substrate with a low doping concentration, the sum of the lengths of the P-type doped region 1002 is large enough, thereby ensuring the effective collection of hole carriers.

[0261] In this embodiment, multiple back-contact batteries 10 in the battery assembly can be connected in series in sequence to form a battery string 100, thereby realizing the series bus output of the current. For example, the series connection of the battery cells can be achieved by setting welding strips (bus bars, interconnecting bars), conductive back plates, etc.

[0262] It is understandable that in such an embodiment, the battery assembly may further include a metal frame, a back plate, a photovoltaic glass and an adhesive film. The adhesive film may be filled between the front and back sides of the back contact battery 10 and the photovoltaic glass, adjacent battery 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. The specific selection may be based on actual conditions and is not limited here.

[0263] Photovoltaic glass can cover the adhesive film on the front side of the back contact cell 10. 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 92%, which can protect the back contact cell 10 without affecting the efficiency of the back contact cell 10 as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the back contact cell 10 together. The presence of the adhesive film can seal and insulate the back contact cell 10 and make it waterproof and moisture-proof.

[0264] The backplane can be attached to the adhesive film on the back of the back contact battery 10. The backplane can protect and support the back contact battery 10 and has reliable insulation, water resistance and aging resistance. There are multiple options for the backplane, which can usually be tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc. It can be set according to specific circumstances and is not limited here. The whole composed of the backplane, back contact battery 10, adhesive film and photovoltaic glass can be set on a metal frame. The metal frame serves as the main external support structure of the entire battery assembly and can stably support and install the battery assembly. For example, the battery assembly can be installed at the required location through the metal frame.

[0265] Embodiment 27

[0266] See also Figure 2 In some embodiments, in at least one back-contact battery 10, the electrical connector is connected to the first sub-grid 11 of the back-contact battery 10 and is located in the first pre-connection area 110 of the back-contact battery 10, and the second sub-grid 12 of the back-contact battery 10 extends into the first pre-connection area 110; the battery string 100 of the battery assembly includes an insulating member 30, which is arranged between the electrical connector and the second sub-grid 12.

[0267] In this way, the insulating member 30 can be used to electrically isolate the first electrical connection member 21 from the second auxiliary grid 12 to reduce the risk of short circuit.

[0268] Specifically, the insulating member 30 covers the entire area of ​​the portion of the second sub-grid 12 extending into the first pre-connection area 110 , thereby ensuring that the portion of the second sub-grid 12 extending into the first pre-connection area 110 cannot contact the first electrical connector 21 .

[0269] Specifically, the insulating member 30 covers and exceeds the portion of the second auxiliary grid 12 extending into the first pre-connection region 110. In this way, when the electrical connector is offset, the risk of the electrical connector and the second auxiliary grid 12 being connected is reduced.

[0270] Embodiment 28

[0271] The photovoltaic system of the embodiment of the present application includes the battery assembly of embodiment twenty-six or twenty-seven.

[0272] In the photovoltaic system of the embodiment of the present application, since the resistivity of the silicon substrate in the back contact cell 10 is greater than or equal to 30Ω·cm, and the ratio of the total length of the first sub-grid 11 connected to the N-type doped region 1001 to the total length of the second sub-grid 12 connected to the P-type doped region 1002 in all the sub-grid groups is 0.66-1.2, it can be ensured that in the back contact cell 10 with a silicon substrate with a low doping concentration, the sum of the lengths of the P-type doped region 1002 is large enough, thereby ensuring the effective collection of hole carriers.

[0273] In this embodiment, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water 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 are not limited to this, that is to say, the photovoltaic system 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 may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple battery components. For example, multiple battery components can 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.

[0274] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0275] In addition, the above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A back contact battery, characterized in that: It includes a silicon substrate, a plurality of first sub-gates and a plurality of second sub-gates; The first auxiliary gate and the second auxiliary gate are respectively connected to the N-type doping region and the P-type doping region of the silicon substrate, and the resistivity of the silicon substrate of the silicon substrate is greater than or equal to 30Ω·cm; The first auxiliary grid and the second auxiliary grid extend along a first direction, are spaced from each other, and are arranged along the first direction to form a row of auxiliary grid groups; a plurality of rows of auxiliary grid groups are spaced from each other and are arranged in sequence along a second direction, and the second direction intersects the first direction; In all the auxiliary grid groups, the ratio of the total length of the first auxiliary grid to the total length of the second auxiliary grid is 0.66-1.

2.

2. The back contact cell according to claim 1, characterized in that: In the first direction, the auxiliary grids located at the first end in a row of the auxiliary grid groups and the auxiliary grids located at the first end in an adjacent auxiliary grid group have opposite polarities; And / or, in the first direction, the auxiliary grids located at the second end in a row of the auxiliary grid groups and the auxiliary grids located at the second end in an adjacent auxiliary grid group have opposite polarities. 3 . The back-contact battery according to claim 1 , wherein in all the sub-grid groups, the ratio of the total length of the first sub-grid to the total length of the second sub-grid is 0.66-1. 4 . The back-contact battery according to claim 3 , wherein in all the sub-grid groups, the ratio of the total length of the first sub-grid to the total length of the second sub-grid is 0.66-0.

95.

5. The back contact battery according to claim 3, characterized in that: The auxiliary grid groups in three adjacent rows are respectively a first group, a second group and a third group; The first sub-grid in the first group includes a first opposite-sex overlapping portion and a first connecting portion, the first sub-grid in the third group includes a second opposite-sex overlapping portion and a second connecting portion, and the corresponding first connecting portion and the second connecting portion form a first pre-connecting region.

6. The back contact cell according to claim 5, characterized in that: In the second group, at least one of the second sub-gates extends into the first pre-connection region.

7. The back contact cell according to claim 6, characterized in that: At least one of the second sub-grids in the second group overlaps with one of the first sub-grids in the first group in the second direction, passes through the first pre-connection region, and extends from both sides of the overlapping first sub-grid to form two extension portions.

8. The back contact battery according to claim 7, characterized in that: The auxiliary grid groups in two adjacent rows are respectively a first group and a second group; The second sub-grid in the first group includes a third opposite-sex overlapping portion and a first protruding portion, the second sub-grid in the second group includes a fourth opposite-sex overlapping portion and a second protruding portion, and the adjacent first protruding portion and the second protruding portion form a second pre-connection region; The first sub-grids in the first group and the second group are disposed on both sides of the second pre-connection region.

9. The back contact cell according to claim 8, characterized in that: In the second group, the length of at least one of the second sub-grids satisfies the following relationship: 0.5X<S1-S2<1.95X; Wherein, S1 is the length of the second sub-grid in the second group, S2 is the length of the corresponding first sub-grid in the first group, and X is the spacing in the first direction between the first sub-grids located on both sides of the second pre-connection area in the first group and the second group.

10. The back contact cell according to claim 5, characterized in that: In the second group, at least one of the second sub-gates avoids the first pre-connection region.

11. The back contact cell according to claim 10, characterized in that: In the second group, two second sub-grids located on both sides of the first pre-connection region overlap with the first sub-grid in the first group in the second direction and extend from both sides of the overlapping first sub-grids to form two extension portions respectively.

12. The back contact cell according to claim 11, characterized in that: The second sub-grid in the first group includes a third opposite-sex overlapping portion and a first protruding portion, the second sub-grid in the second group includes a fourth opposite-sex overlapping portion and a second protruding portion, and the adjacent first protruding portion and the second protruding portion form a second pre-connection region; The first sub-gates in the first group and the second group are disposed on both sides of the second pre-connection region.

13. The back contact cell according to claim 12, characterized in that: In the second group, the length of at least one of the second sub-grids satisfies the following relationship: 0.5XD<S3+S4-S2<1.95XD; Among them, S3 and S4 are respectively the lengths of the two second sub-grids located on both sides of the first pre-connection area in the second group, S2 is the length of the corresponding first sub-grid in the first group, X is the spacing in the first direction between the two first sub-grids located on both sides of the second pre-connection area in the first group and the second group, and D is the spacing between the two second sub-grids located on both sides of the first pre-connection area.

14. The back contact cell according to claim 1, characterized in that The silicon substrate comprises a plurality of N-type doping regions and a plurality of P-type doping regions, the first auxiliary gate is arranged on the N-type doping regions, and the second auxiliary gate is arranged on the P-type doping regions; The N-type doping region and the P-type doping region extend along the first direction, the N-type doping region and the P-type doping region are arranged along the first direction to form a row of doping region groups, and a plurality of rows of the doping region groups are sequentially arranged along the second direction; In all the doping region groups, the ratio of the total area of ​​the N-type doping regions to the total area of ​​the P-type doping regions is 0.66-1.

2.

15. The back contact cell according to claim 14, characterized in that In all the doping region groups, the ratio of the total area of ​​the N-type doping regions to the total area of ​​the P-type doping regions is 0.66-1.

16. The back contact cell according to claim 14, characterized in that In all the doping region groups, the ratio of the total area of ​​the N-type doping regions to the total area of ​​the P-type doping regions is 0.66-0.

95.

17. The back contact cell according to claim 14, characterized in that The doping region groups in three adjacent rows are respectively a first region group, a second region group and a third region group; The N-type doped region in the first region group includes a first heterosexual overlapping region and a first connection region, the N-type doped region in the third region group includes a second heterosexual overlapping region and a second connection region, and the adjacent first connection region and the second connection region form a first pre-connection region.

18. The back contact cell according to claim 17, characterized in that In the second region group, the P-type doping region extends into the first pre-connection region.

19. The back contact cell according to claim 18, characterized in that At least one of the P-type doped regions in the second region group overlaps with one of the N-type doped regions in the first region group in the second direction, penetrates the first pre-connection region, and extends from both sides of the overlapping N-type doped region to form two extended regions.

20. The back contact cell according to claim 19, characterized in that The P-type doped region in the first region group includes a third heterosexual overlapping region and a first protruding region, the P-type doped region in the second region group includes a fourth heterosexual overlapping region and a second protruding region, and the adjacent first protruding region and the second protruding region form a second pre-connection region; The N-type doping regions in the first region group and the second region group are disposed on both sides of the second pre-connection region.

21. The back contact cell according to claim 20, characterized in that In the second region group, the length of at least one of the P-type doping regions satisfies the following relationship: 0.5x<s1-s2<1.95x; Among them, s1 is the length of the P-type doping region in the second regional group, s2 is the length of the corresponding N-type doping region in the first regional group, and x is the distance in the first direction between the two N-type doping regions in the first regional group and the second regional group respectively located on both sides of the second pre-connection region.

22. The back contact cell according to claim 17, characterized in that In the second region group, the P-type doping region avoids the first pre-connection region.

23. The back contact cell according to claim 22, characterized in that In the second region group, the two P-type doped regions located on both sides of the first pre-connection region overlap with the N-type doped region in the first region group in the second direction, and extend from both sides of the overlapping N-type doped regions to form two extended regions respectively.

24. The back contact cell according to claim 23, characterized in that The P-type doped region in the first region group includes a third heterosexual overlapping region and a first protruding region, the P-type doped region in the second region group includes a fourth heterosexual overlapping region and a second protruding region, and the adjacent first protruding region and the second protruding region form a second pre-connection region; The N-type doping regions in the first region group and the second region group are disposed on both sides of the second pre-connection region.

25. The back contact cell according to claim 24, characterized in that In the second region group, the length of at least one of the P-type doping regions satisfies the following relationship: 0.5xd<s3+s4-s2<1.95xd; Among them, s3 and s4 are respectively the lengths of the two P-type doped regions in the second regional group located on both sides of the first pre-connection region, s2 is the length of the corresponding N-type doped region in the first regional group, x is the distance in the first direction between the two N-type doped regions in the first regional group and the second regional group respectively located on both sides of the second pre-connection region, and d is the distance between the two P-type doped regions located on both sides of the first pre-connection region.

26. A battery assembly, characterized in that: The invention comprises a plurality of electrical connectors and a plurality of back-contact cells according to any one of claims 1 to 25, wherein the electrical connectors connect a first sub-grid of one of the back-contact cells and a second sub-grid of an adjacent back-contact cell.

27. The battery assembly according to claim 26, characterized in that: In at least one of the back-contact cells, the electrical connector is connected to the first sub-grid of the back-contact cell and is located in the first pre-connection area of ​​the back-contact cell, and the second sub-grid of the back-contact cell extends into the first pre-connection area; the battery string of the battery assembly includes an insulating member, and the insulating member is arranged between the electrical connector and the second sub-grid.

28. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 26 or 27.

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