A back contact cell and photovoltaic module

Abstract

The utility model provides a kind of back contact battery, photovoltaic module, it is related to photovoltaic technical field.The back contact battery includes substrate, back contact battery is not set main grid;First area is formed with first fine grid, second area is formed with second fine grid;First fine grid includes the first fine grid main body and at least one first subgrid of being connected;Second fine grid includes the second fine grid main body and at least one second subgrid of being connected, second fine grid main body is parallel to first fine grid main body, and second fine grid main body and first fine grid main body are spaced apart and set alternately;First fine grid main body and its parallel first solder strip connection, second fine grid main body and its parallel second solder strip connection;First subgrid and second subgrid are located between adjacent first fine grid main body and second fine grid main body, and at least part of first subgrid extends between second fine grid main body and second subgrid, at least part of second subgrid extends between first fine grid main body and first subgrid.The back contact battery can improve electrical performance.

Description

Technical Field

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

[0002] The statements in this section merely provide background information related to this utility model and do not necessarily constitute related technology.

[0003] In back contact (BC) batteries, gridless technology is generally used to reduce the amount of silver paste used, thereby reducing costs.

[0004] Related technology provides a back-contact battery with a fine grid on its back side, but no main grid. Current is collected through the fine grid, with a first fine grid located in the P-region and a second fine grid located in the N-region parallel to each other. This back-contact battery can be connected to other back-contact batteries via a first solder ribbon and a second solder ribbon. Specifically, the first solder ribbon is perpendicular to multiple first fine grids on the back side of the back-contact battery and forms a point contact connection, and the second solder ribbon is perpendicular to multiple second fine grids on the back side of the back-contact battery and forms a point contact connection. Connecting multiple back-contact batteries via the first and second solder ribbons can form a battery string, which can then be further packaged into a photovoltaic module. However, this photovoltaic module has a relatively high series resistance, which is detrimental to improving electrical performance. Utility Model Content

[0005] The purpose of this invention is to provide a back-contact battery and photovoltaic module to solve the technical problem of high series resistance and improve electrical performance.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] In a first aspect, the present invention provides a back contact battery, including a substrate having a first surface, the first surface including a first region, a second region and a third region electrically isolating the first region and the second region; the first region and the second region have opposite conductivity types;

[0008] The back contact battery does not have a main grid.

[0009] A first fine grid is formed on the first region, and a second fine grid is formed on the second region; the first fine grid includes a connected first fine grid body and at least one first sub-grid;

[0010] The second fine gate includes a connected second fine gate body and at least one second sub-gate, the second fine gate body is parallel to the first fine gate body, and the second fine gate body and the first fine gate body are alternately arranged at intervals;

[0011] The first fine grid body is used to connect with a first solder strip parallel to it, and the second fine grid body is used to connect with a second solder strip parallel to it;

[0012] The first sub-gate and the second sub-gate are both located between adjacent first fine gate bodies and second fine gate bodies, and at least a portion of the first sub-gate extends between the second fine gate body and the second sub-gate, and at least a portion of the second sub-gate extends between the first fine gate body and the first sub-gate.

[0013] Optionally, the first sub-gate includes a first segment and at least one second segment connected to the first segment; the second sub-gate includes a third segment and at least one fourth segment connected to the third segment;

[0014] The first fine gate body, the second fine gate body, the second segment, and the fourth segment all extend along a first direction; and / or, the first segment is perpendicular to the first fine gate body; and / or, the third segment is perpendicular to the second fine gate body.

[0015] Optionally, the lengths of the first segment and the third segment in the second direction are both greater than 1 / 2 of the distance between the first fine grid body and the second fine grid body, and the second direction is perpendicular to the first direction;

[0016] And / or, the lengths of the second segment and the fourth segment in the first direction are both greater than 1 / 2 of the distance between the first segment and the third segment.

[0017] Optionally, the first sub-gate includes a plurality of second segments located on the same side of the first segment between adjacent first fine gate bodies and second fine gate bodies, and the second sub-gate includes a plurality of fourth segments located on the same side of the third segment between adjacent first fine gate bodies and second fine gate bodies;

[0018] The plurality of second segments of the first sub-gate located between adjacent first and second fine gate bodies are arranged in an interdigital pattern with the plurality of fourth segments of the corresponding second sub-gate.

[0019] Optionally, the first sub-gate includes at least two second segments located on both sides of the first segment, and the second segments located on both sides of the first segment are arranged symmetrically or asymmetrically with respect to the first segment;

[0020] The second sub-gate includes at least two fourth segments located on both sides of the third segment, and the fourth segments located on both sides of the third segment are arranged symmetrically or asymmetrically with respect to the third segment;

[0021] Preferably, when one end of multiple second segments is connected to a first segment located between adjacent first fine grid bodies and second fine grid bodies, and when one end of multiple fourth segments is connected to a third segment located between adjacent first fine grid bodies and second fine grid bodies, multiple second segments and multiple fourth segments located between adjacent first fine grid bodies and second fine grid bodies are arranged in a cross-finger pattern.

[0022] Optionally, the length of the first segment is the same as the length of the third segment; and / or,

[0023] the length of the second segment is the same as the length of the fourth segment.

[0024] Optionally, at least one first sub-grid is located on one side of the first fine grid body;

[0025] when the number of the first sub-grids is multiple, multiple first sub-grids are respectively located on both sides of the first fine grid body and are symmetrically arranged with respect to the first fine grid body; and / or,

[0026] at least one second sub-grid is located on one side of the second fine grid body;

[0027] when the number of the second sub-grids is multiple, multiple second sub-grids are respectively located on both sides of the second fine grid body and are symmetrically arranged with respect to the second fine grid body.

[0028] Optionally, the first fine grid body and / or the second fine grid body includes one of a discontinuous linear structure, a dot structure, or a continuous strip structure arranged along a first direction.

[0029] Optionally, when the numbers of the first sub-grid and the second sub-grid are both multiple, the structures of multiple first sub-grids include at least one of an L shape, an F shape, a T shape, a tu shape, and a feng shape;

[0030] the structures of multiple second sub-grids include at least one of an L shape, an F shape, a T shape, a tu shape, and a feng shape;

[0031] Preferably, the range of the number of the first sub-grids on the same first fine grid is 1 to 200; and / or,

[0032] the range of the number of the second sub-grids on the same second fine grid is 1 to 200; and / or,

[0033] the range of the total number of the first fine grid body and the second fine grid body is 80 to 400.

[0034] Preferably, the material of the first fine grid and / or the second fine grid includes at least one of silver, silver alloy, copper, copper alloy, and nickel; and / or,

[0035] The substrate is either an N-type substrate or a P-type substrate.

[0036] Secondly, this utility model also provides a photovoltaic module, including any of the back contact cells, a first solder strip, and a second solder strip as mentioned above;

[0037] The first solder strip is parallel to the first fine grid body of the back contact battery and covers and is soldered to the first fine grid body. The second solder strip is parallel to the second fine grid body of the back contact battery and covers and is soldered to the second fine grid body.

[0038] In one or more technical solutions provided in the exemplary embodiments of this utility model, at least one of the following beneficial effects can be achieved.

[0039] The back contact battery of this exemplary embodiment is based on a first fine grid body for connection with a first solder strip parallel to it, and a second fine grid body for connection with a second solder strip parallel to it. That is, the first solder strip covers the first fine grid body and is welded to it, and the second solder strip covers the second fine grid body and is welded to it. Compared with back contact batteries of the same size where the solder strips and fine grids form point contact perpendicularly, each first fine grid body is connected to one first solder strip, and each second fine grid body is connected to one second solder strip. The number of first and second solder strips can be comparable to the number of first and second fine grid bodies, respectively, and the total number of first and second solder strips is greater than the total number of solder strips in the related technology. Thus, the back contact battery of this invention has more solder strips, lower resistance, and a larger contact area between the solder strips and the fine grid, which is beneficial for current conduction. Furthermore, the line resistance of the solder strips is less than the line resistance of the fine grid, thereby reducing series resistance and improving the electrical performance of photovoltaic modules using this back contact battery.

[0040] Furthermore, the first sub-gate and the second sub-gate can serve as branches of the first fine gate body and the second fine gate body, respectively, to collect photogenerated carriers between them. Thus, the first sub-gate and the second sub-gate can expand the carrier collection range of the first fine gate body and the second fine gate body. The current can be discharged in the area between the first fine gate body and the second fine gate body through the solder ribbons on the first fine gate body and the second fine gate body, without the need to lay solder ribbons on the first sub-gate and the second sub-gate, that is, without the need to lay solder ribbons between the first fine gate body and the second fine gate body. This reduces the number of solder ribbons in the entire cell, lowers the difficulty of the manufacturing process, and avoids the problem of back contact cell warping. Attached Figure Description

[0041] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification.

[0042] Figure 1 This is a schematic diagram of the structure of a back contact battery according to an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the structure of a back contact battery (with solder strips laid) according to an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the structure of a back contact battery according to another embodiment of the present invention;

[0045] Figure 4 This is a structural schematic diagram of a back contact battery (with solder strip laid) according to another embodiment of the present invention;

[0046] Figure 5 This is a schematic diagram of the structure of a back contact battery in the first related technology;

[0047] Figure 6 This is a schematic diagram of the structure of a back contact battery (with solder strips laid) in the first related technology.

[0048] Figure label:

[0049] 10. First fine grid; 11. First sub-grid; 111. First segment; 112. Second segment; 12. Main body of the first fine grid;

[0050] 20. Second fine grid; 21. Main body of the second fine grid; 22. Second sub-grid; 223. Third segment; 224. Fourth segment;

[0051] 31. First weld strip; 32. Second weld strip;

[0052] 40. Insulation layer. Detailed Implementation

[0053] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0054] Figure 5 This is a schematic diagram of the structure of a back contact battery in the first related technology; Figure 6 This is a schematic diagram of the back contact battery (with solder strips laid) in the first related technology. See also Figure 5 and Figure 6In the first related technology, the gridless back contact battery uses a first region E1 and a second region E2 that are parallel to each other and are alternately formed on the back of the cell. The two regions have opposite conductivity types and are electrically isolated by a third region E3. The first fine grid 10 and the second fine grid 20 extend along the first region E1 and the second region E2, respectively, forming straight grid lines. To conduct current, solder ribbons are used across each grid line. The first solder ribbon 31 is perpendicular to and electrically connected to the first fine grid 10, while being electrically isolated from the second fine grid 20 by an insulating layer 40. The second solder ribbon 32 is perpendicular to and electrically connected to the second fine grid 20, while being electrically isolated from the first fine grid 10 by an insulating layer 40. The first solder ribbon 31 and the second solder ribbon 32, with opposite polarities, are alternately arranged on the back.

[0055] In the first related technology, the aforementioned insulating layer 40 needs to be formed on the grid lines (first grid 10 or second grid 20) by printing, which increases production costs. On the other hand, the more first solder ribbons 31 and second solder ribbons 32 there are, the better the current collection effect. However, since the first solder ribbons 31 and second solder ribbons 32 are in point contact with the grid lines and the total number of solder ribbons is relatively small, generally 9 to 22, when multiple cells are electrically connected by the first solder ribbons 31 and second solder ribbons 32, the series resistance is not easy to reduce, which is not conducive to improving the electrical performance of photovoltaic modules such as short-circuit current, fill factor, and efficiency.

[0056] To address the aforementioned issues, the exemplary embodiment of this invention provides a back-contact battery that rearranges the first region E1 and the second region E2, lays solder ribbons on the fine grid (first fine grid body or second fine grid body) to form line contacts, and forms a first sub-grid and a second sub-grid between the first fine grid body and the second fine grid body for carrier collection. When connected with solder ribbons, compared to the first related technology, the total number of solder ribbons is increased, the series resistance is reduced, and the number of solder ribbons can be controlled within a suitable range to avoid problems such as cell warping. In addition, the solder ribbons have a lower line resistance than the fine grid, which can also reduce the series resistance and improve the electrical performance of the photovoltaic module.

[0057] Figure 1 This is a schematic diagram of the structure of a back contact battery according to an embodiment of the present invention; Figure 2 This is a structural schematic diagram of a back contact battery (with solder strips laid) according to an embodiment of this utility model. See also... Figure 1 and Figure 2As shown, an exemplary embodiment of the present invention provides a back contact battery, including a substrate having a first surface. The first surface includes a first region E1, a second region E2, and a third region E3 electrically isolating the first region E1 and the second region E2. The first region E1 and the second region E2 have opposite conductivity types. The back contact battery does not have a main grid to reduce the amount of electrode paste used and increase the light-receiving area, etc. A first fine grid 10 is formed on the first region E1, and a second fine grid 20 is formed on the second region E2. The first fine grid 10 includes a connected first fine grid body 12 and at least one first sub-grid 11. The second fine grid 20 includes a connected second fine grid body 21 and at least one second sub-grid 22. The second fine gate body 21 is parallel to the first fine gate body 12, and the second fine gate body 21 and the first fine gate body 12 are alternately arranged at intervals; the first fine gate body 12 is used to connect with the first solder strip 31 parallel to it, and the second fine gate body 21 is used to connect with the second solder strip 32 parallel to it; the first sub-gate 11 and the second sub-gate 22 are both located between adjacent first fine gate bodies 12 and second fine gate bodies 21, and at least a portion of the first sub-gate 11 extends between the second fine gate body 21 and the second sub-gate 22, and at least a portion of the second sub-gate 22 extends between the first fine gate body 12 and the first sub-gate 11.

[0058] It should be noted that the first fine grid body 12 is used to lay the first solder strip 31 on it, and the second fine grid body 21 is used to lay the second solder strip 32 on it. The orthographic projections of the first sub-grid 11 and the second sub-grid 22 on a preset plane overlap each other, and the preset plane is parallel to the extension direction of the first fine grid body 12 or the second fine grid body 21.

[0059] In practical applications, the first surface of the substrate of the back contact battery is the back side. Each first grid 10 extends along the corresponding first region E1, meaning their general orientations are consistent. Each second grid 20 extends along the corresponding second region E2, also meaning their general orientations are consistent. The first grid body 12 of the first grid 10 and the second grid body 21 of the second grid 20 extend along a first direction. The first grid body 12 and the second grid body 21 are arranged alternately along a second direction, which can be perpendicular to the first direction. The length of the first grid body 12 and the second grid body 21 in the first direction is approximately equal to the length of the entire back contact battery in the first direction. Corresponding solder strips can be laid on each first grid body 12 and second grid body 21 to conduct current.

[0060] Compared to the method in the first related art where the solder ribbon crosses each grid line to conduct current through point contact, in the exemplary embodiment of this utility model, the first solder ribbon 31 is laid on the first fine grid body 12, and the second solder ribbon 32 is laid on the second fine grid body 21. Since each first fine grid body 12 is connected to one first solder ribbon 31, and each second fine grid body 21 is connected to one second solder ribbon 32, the number of first solder ribbons 31 and second solder ribbons 32 can be equivalent to the number of first fine grid bodies 12 and second fine grid bodies 21, respectively. The total number of first solder ribbons 31 and second solder ribbons 32 is greater than the total number of solder ribbons in the related art (in the related art, the solder ribbons are vertically connected to the fine grid, and the number of solder ribbons is much smaller than the number of fine grids). In this way, the back contact cell in the embodiment of this utility model has more solder ribbons, lower resistance, and a larger contact area between the solder ribbons and the fine grid, which is conducive to current conduction. Moreover, the line resistance of the solder ribbons is less than the line resistance of the fine grid, thereby reducing the series resistance and improving the electrical performance of the photovoltaic module using this back contact cell.

[0061] It should be noted that when a back contact battery is connected to multiple solder strips, it can be understood as dividing the back contact battery into multiple sub-back contact battery units. These multiple sub-back contact battery units are connected in parallel through solder strips. The more solder strips there are, the more sub-back contact battery units there are, thereby reducing the resistance.

[0062] To ensure carrier collection efficiency, the spacing between the first fine gate body 12 and the second fine gate body 21 needs to be sufficiently small. Therefore, the number of solder strips is greater than that of the scheme in the first related art that spans across each fine gate. For example, the total number of the first fine gate body 12 and the second fine gate body 21 ranges from 80 to 400. Exemplarily, the total number of the first fine gate body 12 and the second fine gate body 21 can be 90, 100, 110, 130, 150, 170, 190, 200, 220, 250, 280, 300, 320, 340, 360, or 380 strips, etc.

[0063] The first sub-gate 11 and the second sub-gate 22 can serve as branches of the first fine gate body 12 and the second fine gate body 21, respectively, to collect photogenerated carriers between them. Thus, the first sub-gate 11 and the second sub-gate 22 can expand the carrier collection range of the first fine gate body 12 and the second fine gate body 21. The current can be discharged in the area between the first fine gate body 12 and the second fine gate body 21 through the first solder strip 31 on the first fine gate body 12 and the second solder strip 32 on the second fine gate body 21. There is no need to lay solder strips on the first sub-gate 11 and the second sub-gate 22, that is, there is no need to lay solder strips between the first fine gate body 12 and the second fine gate body 21. This reduces the number of solder strips, lowers the difficulty of the manufacturing process, and avoids the problem of back contact battery warping.

[0064] In addition, in the second related technology, the first and second regions of the substrate are arranged in parallel, the first and second fine gates are arranged in parallel, and the first and second fine gates are located in the middle of the first and second regions, respectively. The first solder ribbon is parallel to the first fine gate and covers the first fine gate, and the second solder ribbon is parallel to the second fine gate and covers the second fine gate. In order to ensure carrier collection, the areas of the first and second regions are relatively small, and the number of the first and second fine gates is relatively large, resulting in an excessive number of solder ribbons, which makes the manufacturing process more difficult and reduces reliability. In order to reduce the number of solder ribbons, in this embodiment of the present invention, a first sub-gate 11 and a second sub-gate 22 are provided between the first fine gate body 12 and the second fine gate body 21 to ensure the carrier collection rate. The first solder ribbon 31 covers the first fine gate body 12 and is welded to it, and the second solder ribbon 32 covers the second fine gate body 21 and is welded to it. The first sub-gate 11 and the second sub-gate 22 are not directly connected to the solder ribbons to reduce the number of solder ribbons. Based on this, the back contact battery provided by this utility model reduces the number of solder strips while ensuring carrier collection efficiency, improving the reliability of battery production, reducing cell warping problems, and saving production costs.

[0065] refer to Figure 1 At least one first sub-gate 11 is located on one side of the first fine gate body 12; when there are multiple first sub-gates 11, the multiple first sub-gates 11 are respectively located on both sides of the first fine gate body 12 and are symmetrically arranged relative to the first fine gate body 12; and / or, at least one second sub-gate 22 is located on one side of the second fine gate body 21; when there are multiple second sub-gates 22, the multiple second sub-gates 22 are respectively located on both sides of the second fine gate body 21 and are symmetrically arranged relative to the second fine gate body 21.

[0066] See also Figure 1 As shown, when the first grid body 12 is located at the edge of the back contact battery, the first grid body 12 has a first sub-grid 11 on the side facing the second grid body 21; while when the first grid body 12 is located in the middle of the battery cell, the first grid body 12 has first sub-grids 11 on both sides, and the first sub-grids 11 on both sides are symmetrically arranged, simplifying the manufacturing process. Exemplarily, the first sub-grids 11 on both sides of the first grid body 12 can also be arranged asymmetrically.

[0067] Similarly, when the second grid body 21 is located at the edge of the solar cell, the second grid body 21 has a second sub-grid 22 on the side facing the first grid body 12; while when the second grid body 21 is located in the middle of the solar cell, the second grid body 21 has second sub-grids 22 on both sides, and the second sub-grids 22 on both sides are symmetrically arranged, simplifying the manufacturing process. For example, the second sub-grids 22 on both sides of the second grid body 21 can also be arranged asymmetrically.

[0068] See also Figure 1 As shown, the first sub-grid 11 includes a first segment 111 and at least one second segment 112 connected to the first segment 111; the second sub-grid 22 includes a third segment 223 and at least one fourth segment 224 connected to the third segment 223; the first fine grid body 12, the second fine grid body 21, the second segment 112, and the fourth segment 224 all extend along a first direction; and / or, the first segment 111 is perpendicular to the first fine grid body 12; and / or, the third segment 223 is perpendicular to the second fine grid body 21. Thus, the structures of the first fine grid 10 and the second fine grid 20 are simple and regular, facilitating production. The first direction can be parallel to the edge of the back contact battery.

[0069] Of course, the first fine grid 10 and the second fine grid 20 can also be other structures. For example, the first sub-grid 11 and the second sub-grid 22 can be other regular or irregular structures such as arc, oblique line, wavy line, etc.

[0070] In some embodiments, see Figures 1 to 4 As shown, the lengths of the first segment 111 and the third segment 223 in the second direction are both greater than half the distance between the first fine gate body 12 and the second fine gate body 21. The second direction is perpendicular to the first direction, which helps to balance the charge carriers collected by the first fine gate 10 and the second fine gate 20 respectively. The second direction can be an extension direction perpendicular to the first fine gate body 12.

[0071] The lengths of the second segment 112 and the fourth segment 224 in the first direction are both greater than half the distance between the first segment 111 and the third segment 223. This creates an intersection between the first sub-gate 11 and the second sub-gate 22, and fully utilizes the first and second regions, improving the carrier collection efficiency of the first and second sub-gates 11 and 22. If at least one of the lengths of the second segment 112 and the fourth segment 224 in the first direction is less than half the distance between the first segment 111 and the third segment 223, then the first sub-gate 11 and the second sub-gate 22 will not be able to form an intersection, or there will be a large number of empty areas in the first and second regions, which is not conducive to fully collecting carriers.

[0072] The first segment 111 and the second segment 112, as well as the third segment 223 and the fourth segment 224, can all have an L-shaped structure, and the first sub-gate 11 and the second sub-gate 22 form an interdigitated structure. Alternatively, the first sub-gate 11 and the corresponding second sub-gate 22 are L-shaped opposite each other, and the second segment 112 and the fourth segment 224 are staggered.

[0073] In some implementations, the length of the first segment 111 can be the same as the length of the third segment 223; the length of the second segment 112 can be the same as the length of the fourth segment 224, so as to ensure the collection efficiency of the charge carriers while making full use of the partition area of ​​the first region E1 and the second region E2, and to balance the charge carriers collected by the first sub-gate 11 and the second sub-gate 22 respectively.

[0074] For example, the number of first sub-gates 11 on the same first fine gate 10 ranges from 1 to 200, such as 2, 4, 6, 10, 20, 40, 60, 70, 80, 90, 110, 130, 140, 160, 180 or 190, etc.

[0075] For example, the number of second sub-gates 22 on the same second fine gate 20 ranges from 1 to 200, such as 2, 4, 6, 10, 20, 40, 60, 70, 80, 90, 110, 130, 140, 160, 180 or 190, etc.

[0076] Figure 3 This is a schematic diagram of the structure of a back contact battery according to another embodiment of the present invention; Figure 4 This is a structural schematic diagram of a back contact battery (with solder strip laid) according to another embodiment of the present invention. See also Figure 3 and Figure 4 As shown, the first sub-grid 11 located in the middle of the solar cell includes at least two second segments 112 located on both sides of the first segment 111, and the second segments 112 located on both sides of the first segment 111 are arranged symmetrically or asymmetrically with respect to the first segment 111; the second sub-grid 22 includes at least two fourth segments 224 located on both sides of the third segment 223, and the fourth segments 224 located on both sides of the third segment 223 are arranged symmetrically or asymmetrically with respect to the third segment 223; the plurality of second segments 112 of the first sub-grid 11 and the plurality of fourth segments 224 of the corresponding second sub-grid 22 are arranged in an interdigital pattern. The symmetrical arrangement is simple, convenient for production, and produces an aesthetically pleasing graphic.

[0077] When the first sub-gate 11 is symmetrically arranged with the second segments 112 on both sides of the first segment 111, for example, the first sub-gate 11 has two second segments 112 and is symmetrically arranged with respect to the first segment 111, the first sub-gate 11 is arranged in a T-shape.

[0078] When the second sub-gate 22 is symmetrically arranged with the fourth segment 224 on both sides of the third segment 223, for example, the second sub-gate 22 has two fourth segments 224 and is symmetrically arranged with respect to the third segment 223, the second sub-gate 22 as a whole is also arranged in a T-shape.

[0079] When one end of a plurality of second segments 112 is connected to a first segment located between adjacent first fine gate bodies 12 and second fine gate bodies 21, and when one end of a plurality of fourth segments 224 is connected to a third segment 223 located between adjacent first fine gate bodies 12 and second fine gate bodies 21, the plurality of second segments 112 and the plurality of fourth segments 224 located between adjacent first fine gate bodies 12 and second fine gate bodies 21 are arranged in an interdigitated pattern. This interdigitated pattern means that the second segments 112 and fourth segments 224 are arranged alternately, and the orthographic projections of the second segments 112 and fourth segments 224 on a plane parallel to the first fine gate body 12 overlap. This allows the second segments 112 and fourth segments 224 to effectively collect charge carriers.

[0080] See also Figure 3 and Figure 4 The first sub-grid 11 located at the edge of the solar cell in the first direction is arranged in an L-shape. That is, on the same solar cell, the first sub-grid 11 has both a T-shaped structure and an L-shaped structure.

[0081] Similarly, the second sub-grid 22 located at the edge of the cell in the first direction is arranged in an L-shape. That is, on the same cell, the second sub-grid 22 has both a T-shaped structure and an L-shaped structure.

[0082] In other embodiments, the first sub-gate 11 includes a plurality of second segments 112 located on the same side of the first segment 111 between adjacent first fine gate bodies 12 and second fine gate bodies 21, and the second sub-gate 22 includes a plurality of fourth segments 224 located on the same side of the third segment 223 between adjacent first fine gate bodies 12 and second fine gate bodies 21; the plurality of second segments 112 of the first sub-gate 11 located between adjacent first fine gate bodies 12 and second fine gate bodies 21 are arranged in an interdigital pattern with the plurality of fourth segments 224 of the corresponding second sub-gate 22.

[0083] For example, the first sub-gate 11 includes two second segments 112 located on the same side of the first segment 111, that is, the first sub-gate 11 is arranged in an F-shape; the second sub-gate 22 includes two fourth segments 224 located on the same side of the third segment 223, that is, the second sub-gate 22 is arranged in an F-shape, and the first sub-gate 11 and the corresponding second sub-gate 22 are arranged opposite to each other and staggered.

[0084] For example, at the same position in the first direction, the first fine grid body 12, the fourth segment 224, the second segment 112, the fourth segment 224, the second segment 112 and the second fine grid body 21 are arranged sequentially along the second direction.

[0085] Exemplarily, the first sub-grid 11 may further include more than two second segments 112 located on the same side of the first segment 111; the second sub-grid 22 may further include more than two fourth segments 224 located on the same side of the third segment 223.

[0086] In some other embodiments, the first sub-grid 11 includes four second segments 112 respectively located on both sides of the first segment 111, that is, two second segments 112 are located on one side of the first segment 111, and the other two second segments 112 are located on the other side of the first segment 111, and the second segments 112 located on both sides of the first segment 111 are symmetrically arranged, and the first sub-grid 11 is in a cross shape. It can be understood that the first sub-grid 11 may further include more than four second segments 112 respectively located on both sides of the first segment 111.

[0087] Similarly, the second sub-grid 22 includes four fourth segments 224 respectively located on both sides of the third segment 223, that is, two fourth segments 224 are located on one side of the third segment 223, and the other two fourth segments 224 are located on the other side of the third segment 223, and the fourth segments 224 located on both sides of the third segment 223 are symmetrically arranged, and the second sub-grid 22 is in a cross shape. It can be understood that the second sub-grid 22 may further include more than four fourth segments 224 respectively located on both sides of the third segment 223.

[0088] In some embodiments, the structures of the first sub-grid 11 and the second sub-grid 22 may include L-shaped, F-shaped, T-shaped, cross-shaped or rich-shaped. When the numbers of the first sub-grid 11 and the second sub-grid 22 are both multiple, the structures of the multiple first sub-grids 11 may be at least one of L-shaped, F-shaped, T-shaped, cross-shaped and rich-shaped. Similarly, the structures of the multiple second sub-grids 22 may include at least one of L-shaped, F-shaped, T-shaped, cross-shaped and rich-shaped. These structures can increase the carrier collection area, and are simple and convenient for production and promotion.

[0089] In some embodiments, in the back-contact battery of the exemplary embodiment of the present invention, the first fine-grid main body 12 and / or the second fine-grid main body 21 includes one of a discontinuous linear structure, a dot structure or a continuous strip structure arranged along the first direction.

[0090] In practical applications, when forming a back-contact battery string with back-contact battery wafers, by laying the first welding tape 31 on the first fine-grid main body 12, and laying the second welding tape 32 on the second fine-grid main body 21 and forming an electrical connection, at this time, the first welding tape 31 and the second welding tape 32 can partially replace the current collection function of the first fine-grid main body 12 and the second fine-grid main body 21, and the conductivity of the welding tape is better than that of the first fine-grid main body 12 and the second fine-grid main body 21. When the first fine-grid main body 12 and the second fine-grid main body 21 are discontinuous linear structures or dot structures, it will not affect the current collection performance. At the same time, when the fine grid is a discontinuous linear structure or a dot structure, it can save the grid line paste and reduce the cost.

[0091] For example, the first fine gate body 12, the second fine gate body 21, the first sub-gate 11, and the second sub-gate 22 can be made of the same material and have the same width. For instance, the materials of the first fine gate body 12, the second fine gate body 21, the first sub-gate 11, and the second sub-gate 22 can include at least one of silver, silver alloy, copper, copper alloy, and nickel, and can be, for example, a stack of the above materials, such as a nickel / copper / silver stacked structure. That is, the first fine gate 10 and the second fine gate 20 include at least one of the aforementioned materials.

[0092] For example, the substrate is either an N-type substrate or a P-type substrate.

[0093] An exemplary embodiment of this utility model also provides a photovoltaic module, including any of the aforementioned back contact cells, a first solder strip 31, and a second solder strip 32. The first solder strip 31 is parallel to the first fine grid body 12 of the back contact cell, covers the first fine grid body 12, and is soldered to it. The second solder strip 32 is parallel to the second fine grid body 21 of the back contact cell, covers the second fine grid body 21, and is soldered to it.

[0094] For example, two corresponding first grid bodies 12 of two adjacent back contact batteries are laid and welded together by the same first solder strip 31 to form an electrical connection, and two corresponding second grid bodies 21 are welded together by another second solder strip 32 to form an electrical connection, thereby forming a battery string in parallel. Alternatively, the first grid body 12 of one back contact battery is connected by the same first solder strip 31, and the second grid body 21 of another back contact battery is connected to form a battery string in series. Multiple battery strings form a battery string array by connecting them in series and / or parallel circuit structures through busbars.

[0095] The photovoltaic module provided in this embodiment of the utility model further includes: a cover plate, a back plate, and an encapsulating film, with the battery string array encapsulated between the cover plate and the back plate by the encapsulating film.

[0096] The photovoltaic module provided in this embodiment of the present invention further includes: a busbar, connected to the solder strip, for converging and discharging the current transported by the solder strip.

[0097] The photovoltaic module provided in this embodiment of the invention features a first fine grid body of a back contact cell connected to a first parallel solder ribbon, and a second fine grid body connected to a second parallel solder ribbon. Specifically, the first solder ribbon covers and is soldered to the first fine grid body, and the second solder ribbon covers and is soldered to the second fine grid body. Compared to related technologies where solder ribbons and the fine grid form a point contact connection perpendicularly and are of the same size, this invention allows for a greater number of solder ribbons than in related technologies. Since each first fine grid body is connected to one first solder ribbon, and each second fine grid body is connected to one second solder ribbon, the number of first and second solder ribbons can be roughly equivalent to the number of first and second fine grid bodies, respectively. The total number of first and second solder ribbons is greater than the total number of solder ribbons in related technologies. This results in a larger number of solder ribbons in the back contact cell, lower resistance, and a larger contact area between the solder ribbons and the fine grid, facilitating current conduction. Furthermore, the line resistance of the solder ribbons is lower than that of the fine grid, thereby reducing series resistance and improving the electrical performance of the photovoltaic module using this back contact cell.

[0098] Furthermore, the first sub-gate and the second sub-gate can serve as branches of the first fine gate body and the second fine gate body, respectively, to collect photogenerated carriers between them. Thus, the first sub-gate and the second sub-gate can expand the carrier collection range of the first fine gate body and the second fine gate body. The current can be discharged in the area between the first fine gate body and the second fine gate body through the solder ribbons on the first fine gate body and the second fine gate body, without the need to lay solder ribbons on the first sub-gate and the second sub-gate, that is, without the need to lay solder ribbons between the first fine gate body and the second fine gate body. This reduces the number of solder ribbons in the entire cell, lowers the difficulty of the manufacturing process, and avoids the problem of back contact cell warping.

[0099] The technological advantages of the aforementioned photovoltaic modules compared to related technologies are the same as those of the aforementioned back-contact batteries, and will not be repeated here.

[0100] Those skilled in the art should understand that the above embodiments are merely for clearly illustrating the present invention and are not intended to limit the scope of the present invention. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A back contact cell, characterized in that, Includes a substrate having a first surface, the first surface including a first region, a second region, and a third region electrically isolating the first region and the second region; the first region and the second region have opposite conductivity types; The back contact battery does not have a main grid. A first fine grid is formed on the first region, and a second fine grid is formed on the second region; the first fine grid includes a connected first fine grid body and at least one first sub-grid; The second fine gate includes a connected second fine gate body and at least one second sub-gate, the second fine gate body is parallel to the first fine gate body, and the second fine gate body and the first fine gate body are alternately arranged at intervals; The first fine grid body is used to connect with a first solder strip parallel to it, and the second fine grid body is used to connect with a second solder strip parallel to it; The first sub-gate and the second sub-gate are both located between adjacent first fine gate bodies and second fine gate bodies, and at least a portion of the first sub-gate extends between the second fine gate body and the second sub-gate, and at least a portion of the second sub-gate extends between the first fine gate body and the first sub-gate.

2. The back contact cell of claim 1, wherein, The first sub-gate includes a first segment and at least one second segment connected to the first segment; the second sub-gate includes a third segment and at least one fourth segment connected to the third segment; The first fine gate body, the second fine gate body, the second segment, and the fourth segment all extend along a first direction; and / or, the first segment is perpendicular to the first fine gate body; and / or, the third segment is perpendicular to the second fine gate body.

3. The back contact battery according to claim 2, characterized in that, The lengths of the first segment and the third segment in the second direction are both greater than 1 / 2 of the distance between the first fine grid body and the second fine grid body, and the second direction is perpendicular to the first direction; And / or, the lengths of the second segment and the fourth segment in the first direction are both greater than 1 / 2 of the distance between the first segment and the third segment.

4. The back contact battery according to claim 2, characterized in that, The first sub-gate includes a plurality of second segments located on the same side of the first segment between adjacent first fine gate bodies and second fine gate bodies, and the second sub-gate includes a plurality of fourth segments located on the same side of the third segment between adjacent first fine gate bodies and second fine gate bodies; The plurality of second segments of the first sub-gate located between adjacent first and second fine gate bodies are arranged in an interdigital pattern with the plurality of fourth segments of the corresponding second sub-gate.

5. The back contact battery according to claim 2, characterized in that, The first sub-gate includes at least two second segments located on both sides of the first segment, and the second segments located on both sides of the first segment are arranged symmetrically or asymmetrically with respect to the first segment; The second sub-gate includes at least two fourth segments located on both sides of the third segment, and the fourth segments located on both sides of the third segment are arranged symmetrically or asymmetrically with respect to the third segment; Preferably, when one end of a plurality of the second segments is connected to a first segment located between adjacent first fine grid bodies and second fine grid bodies, and when one end of a plurality of the fourth segments is connected to a third segment located between adjacent first fine grid bodies and second fine grid bodies, a plurality of the second segments and a plurality of the fourth segments located between adjacent first fine grid bodies and second fine grid bodies are arranged in an interdigitated pattern.

6. The back contact battery according to claim 2, characterized in that, The length of the first segment is the same as the length of the third segment; and / or, The length of the second segment is the same as the length of the fourth segment.

7. The back contact battery according to claim 1, characterized in that, The at least one first sub-grid is located on one side of the first fine grid body; When the number of the first sub-grids is multiple, the multiple first sub-grids are respectively located on both sides of the first fine grid body and are symmetrically arranged with respect to the first fine grid body; and / or, The at least one second sub-grid is located on one side of the second fine grid body; When the number of the second sub-grids is multiple, the multiple second sub-grids are respectively located on both sides of the second fine grid body and are symmetrically arranged with respect to the second fine grid body.

8. The back contact battery according to claim 1, characterized in that, The first fine grid body and / or the second fine grid body includes one of a discontinuous linear structure, a dot structure, or a continuous strip structure arranged along a first direction.

9. The back contact battery according to claim 1, characterized in that, The structures of the first sub-grid and the second sub-grid are one of an L shape, an F shape, a T shape, a cross shape, and a rich shape; When the numbers of the first sub-grids and the second sub-grids are both multiple, the structures of the multiple first sub-grids include at least one of an L shape, an F shape, a T shape, a cross shape, and a rich shape; the structures of the multiple second sub-grids include at least one of an L shape, an F shape, a T shape, a cross shape, and a rich shape; Preferably, the range of the number of the first sub-grids on the same first fine grid is 1 to 200; and / or, The range of the number of the second sub-grids on the same second fine grid is 1 to 200; and / or, the range of the total number of the first fine grid body and the second fine grid body is 80 to 400; Preferably, the material of the first fine grid and / or the second fine grid includes at least one of silver, silver alloy, copper, copper alloy, and nickel; and / or, The substrate is one of an N-type substrate or a P-type substrate.

10. A photovoltaic module, characterized in that, Comprising the back-contact battery according to any one of claims 1-9, a first welding strip, and a second welding strip; The first welding strip is parallel to the first fine grid body of the back-contact battery, covers the first fine grid body, and is welded and connected thereto, and the second welding strip is parallel to the second fine grid body of the back-contact battery, covers the second fine grid body, and is welded and connected thereto.

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