Back contact solar cell string and assembly and system thereof

Abstract

The utility model relates to the technical field of solar cells, and particularly discloses a back contact solar cell string and an assembly and system thereof, and the back contact solar cell string comprises at least two cells, a first welding strip, a second welding strip, and a first extension insulation module. Each battery piece comprises a first extension grid line connected with the end part of the first main grid, and the first extension grid line extends to a preset position of the first edge and / or the second edge along the first direction to form a first grid line protruding part; the first welding strip is used for connecting the first main grid of one battery piece and the second main grid of the adjacent battery piece; the second welding strip is used for connecting the second main grid of one battery piece and the first main grid of the adjacent battery piece; the first extension insulation module is arranged in a contact area of the second welding strip and the first extension grid line, so that the second welding strip is in insulation connection with the first extension grid line. By adopting the solar cell string, the technical problems of improving the carrier collection efficiency and the conversion efficiency of the solar cell and improving the reliability of the solar cell string can be solved.

Description

Technical Field

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

[0002] A back-contact solar cell is a cell in which both the emitter and base contact electrodes are placed on the back side of the cell (non-light-receiving side). The light-receiving side of the cell is not blocked by any metal electrodes, which effectively increases the short-circuit current of the cell. At the same time, the back side can allow for wider metal grid lines to reduce the series resistance and thus increase the fill factor. This type of cell with no obstruction on the front side not only has a high conversion efficiency, but also looks more beautiful. At the same time, components with full back electrodes are easier to assemble.

[0003] The back-contact cell forms alternating P-type doped regions and N-type doped regions on the backlit surface, with the metal electrode correspondingly covering the backlit surface. The current transmission of carriers inside the cell is mainly lateral transmission. Since the back-contact cell has no metal electrode blocking the light-receiving surface, it can avoid shading losses and improve the conversion efficiency to a certain extent. However, due to the long lateral transmission distance, the lateral transmission of most carriers will cause significant series resistance loss, resulting in limited improvement in conversion efficiency. In addition, the back-contact cell has very few openings in the area corresponding to the main grid, resulting in little carrier collection and low efficiency.

[0004] For back-contact solar cells, electrode pattern design is the core technology of the battery. How to improve the efficiency of carrier collection and the conversion efficiency of solar cells by improving the electrode pattern has become a technical problem that needs to be urgently solved by technical personnel in this field. Utility Model Content

[0005] The utility model provides a back-contact solar cell string and its components and system, which can solve the technical problem of improving the carrier collection efficiency and the conversion efficiency of solar cells.

[0006] In order to solve the above technical problems, the present invention provides a back-contact solar cell string, comprising:

[0007] At least two solar cells, each of the solar cells including alternating first polarity regions and second polarity regions, a first grid line for collecting the first polarity regions, a second grid line for collecting the second polarity regions, and a first busbar connected to the first grid line and a second busbar connected to the second grid line, wherein the first grid line includes a first extended grid line connected to an end of the first busbar, the first extended grid line extending along a first direction to a predetermined position of the first edge and / or the second edge to form a first grid line protrusion;

[0008] A first welding ribbon, wherein the first welding ribbon is used to connect the first busbar of a solar cell and the second busbar of an adjacent solar cell;

[0009] A second welding ribbon, wherein the second welding ribbon is used to connect the second main grid of a solar cell and the first main grid of an adjacent solar cell;

[0010] The first extending insulating module is provided in a contact area between the second welding strip and the first extending gate line, so as to insulate the second welding strip from being connected to the first extending gate line.

[0011] Optionally, a width of the first extended insulating module along the first direction is greater than a width of the second main grid and greater than a width of the second welding strip.

[0012] Optionally, a ratio w1 of the width of the first extended insulating module along the first direction to the width of the second main grid is 1.1≤w1≤3, and a ratio w2 of the width of the first extended insulating module along the first direction to the width of the second welding strip is 1.05≤w2≤2.

[0013] Optionally, a gate line insulation module is further included, which is arranged at the first gate line near the second main grid to insulate the first gate line from the second main grid and the second welding strip; and / or, the gate line insulation module is arranged at the second gate line near the first main grid to insulate the second gate line from the first main grid and the first welding strip.

[0014] Optionally, the second main grid includes a second edge main grid and other second main grids arranged on the side of the back contact battery close to the second edge, the length of the second edge main grid along the second direction is less than or equal to the length of the other second main grids, and the first extended grid line extends along the first direction to a preset position of the second edge to form a first grid line protrusion.

[0015] Optionally, the first gate line protrusion protrudes from the second edge bus bar, or is flush with the second edge bus bar.

[0016] Optionally, the length of the first gate line protrusion is d1, the distance between the first gate line protrusion and the second edge is d2, and d1:d2=(2-5):(1-2).

[0017] Optionally, a length d1 of the first gate line protrusion is 300-2000 μm.

[0018] Optionally, the second gate line includes a second extended gate line connected to an end of the second main gate, and the second extended gate line extends along the first direction to a preset position of the first edge and / or the second edge to form a second gate line protrusion.

[0019] Optionally, a second extending insulating module is further included, and the second extending insulating module is provided in a contact area between the first welding strip and the second extending gate line, so as to insulate the first welding strip from the second extending gate line.

[0020] Optionally, a width of the second extended insulating module along the first direction is greater than a width of the first main grid and greater than a width of the first welding strip.

[0021] Optionally, a ratio w3 of the width of the second extended insulating module along the first direction to the width of the first main grid is 1.1≤w3≤3, and a ratio w4 of the width of the first extended insulating module along the first direction to the width of the first welding strip is 1.05≤w4≤2.

[0022] Optionally, the first extending insulating module and the second extending insulating module are insulating blocks or insulating strips.

[0023] Optionally, the first main grid includes a first edge main grid and other first main grids arranged on the side of the back contact battery close to the first edge, the length of the first edge main grid along the second direction is less than or equal to the length of the other first main grids, and the second extended grid line extends along the first direction to a preset position of the first edge to form a second grid line protrusion.

[0024] Optionally, the second gate line protrusion protrudes from the first edge bus bar, or is flush with the first edge bus bar.

[0025] Optionally, the length of the second gate line protrusion is d3, the distance between the second gate line protrusion and the first edge is d4, and d3:d4=(2-5):(1-2).

[0026] Optionally, a length d3 of the second gate line protrusion is 300-2000 μm.

[0027] Optionally, the first main gate is provided with a first Pad point, and the number of the second extended gate lines is less than the number of the first Pad points; the second main gate is provided with a second Pad point, and the number of the first extended gate lines is less than the number of the second Pad points.

[0028] Optionally, the first main gate is a segmented main gate, wherein the first main gate includes several first segmented main gates, and the first gate line includes several first extended gate lines connected to the ends of the first segmented main gates, each of the first extended gate lines passes through all the first segmented main gates arranged along the first direction, and extends along the first direction to a preset position of the second edge to form a first gate line protrusion.

[0029] Optionally, the first segmented main gate and the first gate line are connected as one through a first extended gate line.

[0030] Optionally, the second main gate includes several second segmented main gates, and the second gate lines include several second extended gate lines connected to the ends of the second segmented main gates, each of the second extended gate lines passes through all the second segmented main gates arranged along the first direction, and extends along the first direction to a preset position of the first edge to form a second gate line protrusion.

[0031] Optionally, the second segmented main gate and the second gate line are connected as one through a second extended gate line.

[0032] Optionally, a third Pad point is provided on the first segmented main gate, and the number of the second extended gate lines is less than the number of the third Pad point; a fourth Pad point is provided on the second segmented main gate, and the number of the first extended gate lines is less than the number of the fourth Pad point.

[0033] Optionally, the first extended gate lines are heterodyne gate lines with opposite polarity to the silicon wafer, the second extended gate lines are homodyne gate lines with the same polarity as the silicon wafer, and the number of the first extended gate lines is greater than the number of the second extended gate lines.

[0034] Optionally, the first extended gate lines are heterogeneous gate lines with opposite polarity to the silicon wafer, and the number is N1; the second extended gate lines are homogeneous gate lines with the same polarity as the silicon wafer, and the number is N2, where N1-N2=(1-2).

[0035] Optionally, when the back contact cell is N-type silicon, the first polarity region is a P-type doped region, and the first extended gate line is a P-type gate line; the second polarity region is an N-type doped region, and the second extended gate line is an N-type gate line;

[0036] When the back contact cell is P-type silicon, the first polarity region is an N-type doped region, and the first extended gate line is an N-type gate line; the second polarity region is a P-type doped region, and the second extended gate line is a P-type gate line.

[0037] Optionally, when the back contact cell is N-type silicon, the first polarity region is a P-type doped region, and the total length of all P-type gate lines is greater than the total length of all N-type gate lines;

[0038] When the back contact cell is P-type silicon, the first polarity region is an N-type doped region, and the total length of all N-type gate lines is greater than the total length of all P-type gate lines.

[0039] Optionally, when the back contact cell is N-type silicon, the first polarity region is a P-type doped region, and the ratio a of the total length of all P-type gate lines to the total length of all N-type gate lines is 1<a≤1.2;

[0040] When the back contact cell is P-type silicon, the first polarity region is an N-type doped region, and the ratio b of the total length of all N-type gate lines to the total length of all P-type gate lines is 1<b≤1.2.

[0041] Optionally, the first extended gate line includes a first edge extended gate line and a first middle extended gate line, the first middle extended gate line is arranged between the fourth Pad points, and the first edge extended gate line is arranged on the side of the back contact battery close to the third edge and / or fourth edge.

[0042] Optionally, the second extended gate line includes a second middle extended gate line, and the second middle extended gate line is provided between the third Pad points.

[0043] Optionally, the first polarity region includes a first polarity extension region, the first polarity extension region extends along a first direction to form a first polarity protrusion, and the first extended gate line is electrically connected to the first polarity region;

[0044] And / or, the second polarity region includes a second polarity extension region, the second polarity extension region extends along the first direction to form a second polarity protrusion, and the second extended gate line is electrically connected to the second polarity region.

[0045] Optionally, the first polarity extension region runs through the back side of the back-contact battery, the first extended gate line runs through the first segmented main gate, and the first extended gate line and the first polarity extension region are fully connected; the second polarity extension region runs through the back side of the back-contact battery, the second extended gate line runs through the second segmented main gate, and the second extended gate line and the second polarity extension region are fully connected.

[0046] Optionally, the first polarity extension region and / or the second polarity extension region is provided with a first opening.

[0047] Optionally, the width of the first opening is 150-450 nm.

[0048] On the other hand, the present invention also provides a back-contact battery assembly, which includes the above-mentioned back-contact battery string.

[0049] On the other hand, the present invention also provides a back-contact battery system, which includes the above-mentioned back-contact battery assembly.

[0050] The implementation of the present invention has the following beneficial effects:

[0051] The utility model provides a back-contact solar cell string comprising at least two cells, a first welding ribbon, a second welding ribbon and a first extended insulating module. The cell comprises a first grid line for collecting a first polarity region, a second grid line for collecting a second polarity region, a first main grid and a second main grid, the first main grid comprising a first edge main grid arranged on a side of the back-contact cell close to the first edge, and the second main grid comprising a second edge main grid arranged on a side of the back-contact cell close to the second edge. The first grid line comprises a first extended grid line connected to an end of the first main grid, the first extended grid line extends along a first direction to a preset position of the first edge and / or the second edge to form a first grid line protrusion. The utility model extends the auxiliary grid line to the GAP area of ​​the edge, and utilizes the grid line protrusion formed by the extension of the first extended grid line to effectively increase the current collection capacity of the area, improve the carrier collection efficiency, effectively reduce the efficiency loss of the edge area of ​​the first edge and / or the second edge, and improve the efficiency of the cell.

[0052] Furthermore, the first busbar is a segmented busbar, comprising a plurality of first segmented busbars, and the first gate lines comprise first extended gate lines connected to the ends of the first segmented busbars. The first extended gate lines penetrate all first segmented busbars arranged along the first direction and extend along the first direction to a predetermined position at the second edge, thereby forming first gate line protrusions. In this case, after the first extended gate lines penetrate all first segmented busbars arranged along the first direction, the first segmented busbars and the first gate lines are integrally connected via the first extended gate lines, thereby providing multiple current collection paths and improving the reliability of current collection.

[0053] Furthermore, the first extended insulating module is located at the contact area between the second welding ribbon and the first extended grid line, thereby isolating the second welding ribbon from the first extended grid line. The first extended insulating module insulates the welding ribbon from the adjacent secondary grid line. The modular design of the first extended insulating module provides excellent insulation and improves the reliability of the battery string. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 is a schematic diagram of a back-contact solar cell string of the present invention;

[0055] Figure 2 Schematic diagram of the electrode structure of the first embodiment of the back contact battery of the present invention;

[0056] Figure 3 yes Figure 2 An enlarged view of section A is shown;

[0057] Figure 4 yes Figure 2 An enlarged view of portion B is shown;

[0058] Figure 5Schematic diagram of the polarity region of the first embodiment of the back contact battery of the present invention;

[0059] Figure 6 Schematic diagram of the extended insulating module of the first embodiment of the back contact battery of the present invention;

[0060] Figure 7 This is a schematic diagram of the electrode structure of the second embodiment of the back contact battery of the present invention;

[0061] Figure 8 yes Figure 7 An enlarged view of section A is shown;

[0062] Figure 9 yes Figure 7 An enlarged view of portion B is shown;

[0063] Figure 10 Schematic diagram of the polarity region of the second embodiment of the back contact battery of the present invention;

[0064] Figure 11 Schematic diagram of the extended insulating module of the second embodiment of the back contact battery of the present invention;

[0065] Figure 12 Schematic diagram of the electrode structure of the third embodiment of the back contact battery of the present invention;

[0066] Figure 13 yes Figure 12 An enlarged view of section A is shown;

[0067] Figure 14 yes Figure 12 An enlarged view of portion B is shown;

[0068] Figure 15 Schematic diagram of the polarity region of the third embodiment of the back contact battery of the present invention;

[0069] Figure 16 It is a schematic diagram of the extended insulating module of the third embodiment of the back contact battery of the present invention. DETAILED DESCRIPTION

[0070] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby stated that any directional terms such as "up," "down," "left," "right," "front," "back," "inside," and "outside" that appear or will appear in this document are based solely on the accompanying drawings and are not intended to limit the present invention.

[0071] The utility model provides a back-contact solar cell string, comprising at least two solar cells, a first soldering ribbon, a second soldering ribbon, and an extended insulating module. The solar cells include polarity regions, grid lines disposed on the polarity regions, and a busbar connected to the grid lines. The grid lines include extended grid lines, and the extended insulating module is used to insulate and connect the extended grid lines to the oppositely polarized soldering ribbons.

[0072] Specifically, each of the solar cells includes alternating first polarity regions and second polarity regions, a first grid line for collecting the first polarity regions, a second grid line for collecting the second polarity regions, and a first busbar connected to the first grid line and a second busbar connected to the second grid line, wherein the first grid line includes a first extended grid line connected to an end of the first busbar, and the first extended grid line extends along a first direction to a preset position of the first edge and / or the second edge to form a first grid line protrusion;

[0073] The first welding ribbon is used to connect the first main grid of a solar cell and the second main grid of an adjacent solar cell;

[0074] The second welding strip is used to connect the second main grid of a solar cell and the first main grid of an adjacent solar cell;

[0075] The first extended insulating module is disposed in a contact area between the second welding strip and the first extended gate line, so as to provide an insulated connection between the second welding strip and the first extended gate line.

[0076] The utility model extends the auxiliary grid line to the GAP area of ​​the edge, and utilizes the grid line protrusion formed by extending the first extended grid line to effectively increase the current collection capacity of the area, improve the carrier collection efficiency, effectively reduce the efficiency loss of the edge area of ​​the first edge and / or the second edge, and improve the efficiency of the battery cell.

[0077] Furthermore, the first extended insulating module is located at the contact area between the second welding ribbon and the first extended grid line, thereby isolating the second welding ribbon from the first extended grid line. The first extended insulating module insulates the welding ribbon from the adjacent secondary grid line. The modular design of the first extended insulating module provides excellent insulation and improves the reliability of the battery string.

[0078] Example 1

[0079] refer to Figures 1-6 This embodiment provides a back-contact solar cell string 101, comprising:

[0080] At least two battery cells 100, each of which includes alternating first polarity regions 60 and second polarity regions 70, a first busbar 10 for collecting the first polarity regions 60; a second busbar 20 for collecting the second polarity regions 70; a first main grid 30 connected to the first busbar 10, the first main grid 30 including a first edge main grid 31 disposed on a side of the back-contact battery cell near the first edge; a second main grid 40 connected to the second busbar 20, the second main grid 40 including a second edge main grid 41 disposed on a side of the back-contact battery cell near the second edge; the first busbar 10 including a first extended busbar 11 connected to an end of the first busbar 30, the first extended busbar 11 extending along a first direction to a predetermined position of the first edge and / or the second edge to form a first busbar protrusion 12;

[0081] A first welding ribbon 200, which is used to connect the first busbar 30 of one cell and the second busbar 40 of an adjacent cell;

[0082] A second welding ribbon 300, which is used to connect the second busbar 40 of one cell to the first busbar 30 of an adjacent cell;

[0083] The first extending insulating module 400 is disposed in the contact area between the second soldering ribbon 300 and the first extended gate line 11 , so as to provide an insulated connection between the second soldering ribbon 300 and the first extended gate line 11 .

[0084] In the electrode structure of this embodiment, the second main grid 40 includes a second edge main grid 41 and other second main grids 42 arranged on the side of the back contact battery close to the second edge. The length of the second edge main grid 41 along the second direction is less than or equal to the length of the other second main grids 42. The first extended grid line 11 extends along the first direction to a preset position of the second edge to form a first grid line protrusion 12. In this case, the second main grid 40 is a continuous main grid. Optionally, the first grid line protrusion 12 protrudes from the second edge main grid 41, or is flush with the second edge main grid 41. Figure 2-4 In the illustrated embodiment, with the dotted line L1 as the boundary, the first extended gate line 11 extends along the first direction to a predetermined position of the second edge to form a first gate line protrusion 12 .

[0085] The utility model extends the auxiliary grid line to the GAP area of ​​the edge, and utilizes the first grid line protrusion 12 formed by extending the first extended grid line 11, which can effectively increase the current collection capacity of the area, improve the carrier collection efficiency, effectively reduce the efficiency loss of the edge area of ​​the first edge and / or the second edge, and improve the efficiency of the battery cell.

[0086] It should be noted that the first gate line 10 is used to collect the current in the first polarity region, and the second gate line 20 is used to collect the current in the second polarity region. If the polarities of the first gate line 10 and the second gate line 20 are opposite, then the polarities of the first polarity region and the second polarity region are also opposite. For example, the first gate line 10 is a positive gate line, used to collect the positive current in the positive region, and the second gate line 20 is a negative gate line, used to collect the negative current in the negative region; or, the first gate line 10 is a negative gate line, used to collect the negative current in the negative region, and the second gate line 20 is a positive gate line, used to collect the positive current in the positive region. Wherein, the positive gate line is provided in the P-type doping region of the back contact battery, and the negative gate line is provided in the N-type doping region of the back contact battery.

[0087] The first grid line 10 and the second grid line 20 are alternately arranged, and the first grid line 10 and the second grid line 20 are both horizontal to the edge line of the back contact battery. The first grid line 10 and the second grid line 20 are alternately arranged in the vertical direction, and the first grid line 10 and the second grid line 20 are both horizontal to the upper edge line and the lower edge line of the back contact battery. The back contact battery is substantially rectangular, and the back contact battery that is substantially rectangular can be, for example, a square, or another rectangle, and can have a standard corner, a cut corner or a rounded corner, which is provided according to actual production needs and is not specifically limited here. At the same time, the number of its first grid line 10 and the second grid line 20 is determined according to the actual back contact battery area size, the width of the first grid line 10 and the second grid line 20 and the distance, which is not specifically limited here. The back contact battery can also be processed in slices, for example, with the dotted line in the horizontal direction in the figure as the boundary, to carry out battery cutting.

[0088] Furthermore, the first gate line 10 or the second gate line 20 is an aluminum gate line, a silver gate line, a copper gate line, or a silver-clad copper gate line. It is understood that in the embodiment of the present invention, the first gate line 10 and the second gate line 20 can be selected to be gate lines of the same or different metal types, for example, the first gate line 10 and the second gate line 20 can both be aluminum gate lines; or the first gate line 10 can be aluminum gate lines and the second gate line 20 can be silver gate lines.

[0089] Preferably, see Figure 3 and 4, the length of the first gate line protrusion 12 is d1, and the distance between the first gate line protrusion 12 and the second edge is d2, and the said d1:d2=(2-5):(1-2), which can effectively increase the current collection capacity of the area, improve the carrier collection efficiency, effectively reduce the efficiency loss of the edge area, and improve the efficiency of the battery cell. When d1:d2 is greater than 5:1, the distance between the first gate line protrusion 12 and the second edge is too small, and the distance between the first polarity extension area connected to it and the second edge is also too small, which will reduce the reliability of the battery, and the battery has the risk of edge cracking, short circuit, etc. When d1:d2 is less than 1:1, the current collection capacity of the first gate line protrusion is limited, and the carrier collection efficiency cannot be effectively improved, and the efficiency loss of the edge area still exists.

[0090] More preferably, the ratio d1:d2=(2-3):1 can further improve the carrier collection efficiency and reduce the efficiency loss in the edge region of the first edge and / or the second edge to a large extent.

[0091] It should be noted that, in conjunction with the diagram, the first direction of this embodiment is the horizontal direction, and the second direction is the vertical direction. The first edge is the edge parallel to the first busbar 30 and is located on the right side of the solar cell. The second edge is the edge parallel to the first busbar 30 and is located on the left side of the solar cell.

[0092] The length d1 of the first gate line protrusion can be set according to specific circumstances, preferably in the range of 300-2000 μm, specifically 300, 500, 800, 1000, 1200, 1500, 1800, 2000 μm, etc., but not limited thereto. The distance d2 between the first gate line protrusion 12 and the second edge can also be set according to specific circumstances, preferably in the range of 60-1000 μm, specifically 60, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 μm, etc., but not limited thereto.

[0093] Further, if Figure 5 As shown, the first polarity region 60 includes a first polarity extension region 61 . The first polarity extension region 61 extends along a first direction to form a first polarity protrusion 62 . The first extended gate line 11 is electrically connected to the first polarity region 60 .

[0094] Specifically, the first polarity region 60 includes a first doped layer and a passivation film layer provided on the first doped layer, the first polarity extension region 61 includes a first extension doped layer and a passivation film layer provided on the first extension doped layer, and the first gate line 10 and the first extension gate line 11 are provided on the passivation film layer.

[0095] In the area corresponding to the first gate line 10 and the first extended gate line 11 (i.e., in the projection area of ​​the first gate line 10 and the first extended gate line 11 on the passivation film layer), openings are opened at positions corresponding to the first doped layer and the second doped layer on the passivation film layer, and the first gate line 10 and the first extended gate line 11 are in contact with the first doped layer and the second doped layer through the openings.

[0096] It should be noted that Figure 5 The first polarity region and the second polarity region shown are merely schematic diagrams, and their specific arrangement (including quantity and size) is adapted to the aforementioned electrode structure.

[0097] Preferably, the first polarity extension region 61 is provided with a first opening, and the first extended gate line 11 is electrically connected to the first doped layer through the first opening.

[0098] Specifically, the first openings can be formed in the passivation film layer by laser drilling. To maximize current collection, the first openings are preferably formed in all first extended doped layers. The first extended gate lines then contact all first extended doped layers through the first openings to maximize current collection. Of course, in some embodiments, the first openings can also be formed in some first extended doped layers, and this is not limited to this specific method.

[0099] Preferably, the width of the first opening is 150-450 nm, and specifically can be 150 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm, 300 nm, 320 nm, 350 nm, 380 nm, 400 nm, 420 nm, or 450 nm, but is not limited thereto. The width of the first opening provided in the first polarity extension region 61 can be the same as the width of the openings in the other first polarity regions and the second polarity regions, or can be slightly smaller than the width of the openings in the other first polarity regions and the second polarity regions.

[0100] Further, if Figure 6 As shown, the width of the first extended insulating module 400 along the first direction is greater than the width of the second main grid 40, and greater than the width of the second welding strip 300, which is conducive to achieving reliable insulation between the welding strip and the adjacent auxiliary grid line, avoiding insulation failure caused by improper operation during the welding process, and improving the reliability of the battery string.

[0101] Preferably, a ratio w1 of the width of the first extended insulating module 400 along the first direction to the width of the second main grid 40 is 1.1≤w1≤3, and a ratio w2 of the width of the first extended insulating module 400 along the first direction to the width of the second welding ribbon 40 is 1.05≤w2≤2. More preferably, a ratio w1 of the width of the first extended insulating module 400 along the first direction to the width of the second main grid 40 is 1.5≤w1≤2.5, and a ratio w2 of the width of the first extended insulating module 400 along the first direction to the width of the second welding ribbon 300 is 1.2≤w2≤2.

[0102] As an optional implementation, the first extending insulating module 400 is an insulating block or an insulating strip, or is made of insulating glue, but is not limited thereto.

[0103] Furthermore, the present invention also includes a gate line insulation module 600, which is arranged at the first gate line 10 near the second main grid 40 to insulate the first gate line 10 from the second main grid 40 and the second welding strip 300; and / or, the gate line insulation module is arranged at the second gate line 20 near the first main grid 30 to insulate the second gate line 20 from the first main grid 30 and the first welding strip 200. The first extended insulation module 400 and the gate line insulation module form an array distribution, which can further improve the reliability of the battery string.

[0104] Example 2

[0105] refer to Figure 7-11 , this embodiment provides a back-contact solar cell string, comprising:

[0106] At least two battery cells 100, each of which includes alternating first polarity regions 60 and second polarity regions 70, a first grid line 10 for collecting the first polarity region, a second grid line 20 for collecting the second polarity region, a first main grid 30 connected to the first grid line, the first main grid 30 including a first edge main grid 31 provided on a side of the back contact cell near the first edge; a second main grid 40 connected to the second grid line, the second main grid 40 including a second edge main grid 41 provided on a side of the back contact cell near the second edge; the first grid line 10 includes a first extended grid line 11 connected to an end of the first main grid 30, the first extended grid line 11 extending along a first direction to a preset position of the first edge and / or the second edge to form a first grid line protrusion 12; the second grid line 20 includes a second extended grid line 21 connected to an end of the second main grid 40, the second extended grid line 21 extending along the first direction to a preset position of the first edge and / or the second edge to form a second grid line protrusion 22;

[0107] A first welding ribbon 200, which is used to connect the first busbar 30 of one cell and the second busbar 40 of an adjacent cell;

[0108] A second welding ribbon 300, which is used to connect the second busbar 40 of one cell to the first busbar 30 of an adjacent cell;

[0109] The first extending insulating module 400 is disposed in the contact area between the second soldering ribbon 300 and the first extended gate line 11 , so as to provide an insulated connection between the second soldering ribbon 300 and the first extended gate line 11 .

[0110] The second extending insulating module 500 is disposed in the contact area between the first soldering ribbon 200 and the second extending gate line 21 to provide an insulated connection between the first soldering ribbon 200 and the second extending gate line 21 .

[0111] Unlike the first embodiment, the second gridline 20 of the second embodiment includes a second extended gridline 21 connected to the end of the second main grid 40, and a second extended insulating module 500 that insulates the first welding ribbon 200 from the second extended gridline 21. This invention extends the secondary gridline to the edge GAP region and utilizes the second gridline protrusion 22 formed by the second extended gridline 21 to effectively increase the current collection capacity in this region, improve carrier collection efficiency, effectively reduce efficiency losses in the edge region, and improve the efficiency of the cell.

[0112] In this embodiment, the first busbar 30 includes a first edge busbar 31 and other first busbars 32 disposed on the side of the back contact cell near the first edge. The length of the first edge busbar 31 along the second direction is less than or equal to the length of the other first busbars 32. The second extended busbar 21 extends along the first direction to a predetermined position of the first edge to form a second busbar protrusion 22. In this case, the first busbar 30 is a continuous busbar. Optionally, the second busbar protrusion 22 protrudes from the first edge busbar 31 or is flush with the first edge busbar 31. Figure 8-9 In the illustrated embodiment, with the dotted line L1 as the boundary, the second extended gate line 21 extends along the first direction to a predetermined position of the first edge to form a second gate line protrusion 22 .

[0113] It should be noted that, in conjunction with the diagram, the first direction of this embodiment is the horizontal direction, and the second direction is the vertical direction. The first edge is the edge parallel to the first busbar 30 and is located on the right side of the solar cell. The second edge is the edge parallel to the first busbar 30 and is located on the left side of the solar cell.

[0114] Preferably, see Figure 8 and Figure 9, the length of the second grid line protrusion 22 is d3, and the distance between the second grid line protrusion 22 and the first edge is d4, and the said d3:d4=(2-5):(1-2), which can effectively increase the current collection capacity of the area, improve the carrier collection efficiency, effectively reduce the efficiency loss in the edge area, and improve the efficiency of the battery cell. When d3:d4 is greater than 5:1, the distance between the second grid line protrusion 22 and the first edge is too small, and the distance between the second polarity extension area connected to it and the first edge is also too small, which will reduce the reliability of the battery, and the battery will have the risk of edge cracking, short circuit, etc. When d3:d4 is less than 1:1, the current collection capacity of the second grid line protrusion 22 is limited, and the carrier collection efficiency cannot be effectively improved, and the efficiency loss in the edge area still exists.

[0115] More preferably, the ratio d3:d4=(2-3):1 can further improve the carrier collection efficiency and reduce the efficiency loss in the edge area to a great extent.

[0116] Specifically, the length d3 of the second gate line protrusion can be set according to specific circumstances, and its preferred range is 300-2000 μm, and specifically can be 300, 500, 800, 1000, 1200, 1500, 1800, 2000 μm, etc., but not limited thereto. The distance d4 between the length d3 of the second gate line protrusion and the first edge can also be set according to specific circumstances, and its preferred range is 60-1000 μm, and specifically can be 60, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 μm, etc., but not limited thereto.

[0117] Regarding the relationship between the extended grid lines and the Pad points, when the main grid is a continuous main grid, the number of extended grid lines is less than the number of PAD points on each main grid. In the above-mentioned embodiment one and embodiment two, a first Pad point 51 is provided on the first main grid 30, and the number of the second extended grid lines 21 is less than the number of the first Pad points 51, specifically, the number of the second extended grid lines 21 is less than the number of the first Pad points 51 on each first main grid 30; a second Pad point 52 is provided on the second main grid 40, and the number of the first extended grid lines 11 is less than the number of the second Pad points 52, specifically, the number of the first extended grid lines 11 is less than the number of the second Pad points 52 on each second main grid 40. The number of the first extended grid lines 11 and the second extended grid lines 21 of the present invention is related to the number of Pad points set on the main grid to ensure that the first extended grid line 11 can pass through the first grid line protrusion 12, better collect carriers, and then merge them into the main grid, and converge through the Pad points, thereby improving the photoelectric conversion efficiency of the solar cell.

[0118] Further, if Figure 10As shown, the first polarity region 60 includes a first polarity extension region 61, which extends along the first direction to form a first polarity protrusion 62, and the first extended gate line 11 is electrically connected to the first polarity region 60. The second polarity region 70 includes a second polarity extension region 71, which extends along the first direction to form a second polarity protrusion 72, and the second extended gate line 21 is electrically connected to the second polarity region 70.

[0119] Specifically, the first polarity region 60 includes a first doped layer and a passivation film layer provided on the first doped layer, the second polarity region 70 includes a second doped layer and a passivation film layer provided on the second doped layer, the first polarity extension region 61 includes a first extended doped layer and a passivation film layer provided on the first extended doped layer, the second polarity extension region 71 includes a second extended doped layer and a passivation film layer provided on the second extended doped layer, and the first gate line 10, the second gate line 20, the first extended gate line 11, and the second extended gate line 21 are provided on the passivation film layer. On the regions corresponding to the first gate line 10, the second gate line 20, the first extended gate line 11, and the second extended gate line 21 (i.e., on the projection regions of the first gate line, the second gate line, the first extended gate line, and the second extended gate line on the passivation film layer), openings are provided on the passivation film layer at positions corresponding to the first doped layer and the second doped layer, and the first gate line, the second gate line, the first extended gate line, and the second extended gate line are in contact with the first doped layer and the second doped layer through the openings.

[0120] It should be noted that Figure 10 The first polarity region and the second polarity region shown are merely schematic diagrams, and their specific arrangement (including quantity and size) is adapted to the aforementioned electrode structure.

[0121] Preferably, the first polarity extension region 61 is provided with a first opening, and the first extended gate line 11 is electrically connected to the first doped layer through the first opening; the second polarity extension region 71 is provided with a first opening, and the second extended gate line 21 is electrically connected to the second doped layer through the first opening.

[0122] Specifically, a first opening can be formed in the passivation film layer by laser drilling. To maximize current collection, the first opening can be preferably formed in all first and second extended doped layers. The first extended gate lines contact all first extended doped layers through the first openings, and the second extended gate lines contact all second extended doped layers through the first openings, to maximize current collection. Of course, in some embodiments, the first openings can also be formed in part of the first and second extended doped layers, and this is not limited to this specific method.

[0123] Preferably, the width of the first opening is 150-450 nm, and specifically can be 150 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm, 300 nm, 320 nm, 350 nm, 380 nm, 400 nm, 420 nm, or 450 nm, but is not limited thereto. The width of the first opening provided in the first polarity extension region and the second polarity extension region can be the same as the width of the openings in the other first polarity regions and the second polarity regions, or can be slightly smaller than the width of the openings in the other first polarity regions and the second polarity regions.

[0124] Further, if Figure 11 As shown, the width of the second extended insulating module 500 along the first direction is greater than the width of the first main grid 30 and greater than the width of the first welding strip 200, which is conducive to achieving reliable insulation between the welding strip and the adjacent auxiliary grid line, avoiding insulation failure caused by improper operation during the welding process, and improving the reliability of the battery string.

[0125] Preferably, a ratio (w3) of the width of the second extended insulating module 500 along the first direction to the width of the first busbar 30 is 1.1≤w3≤3, and a ratio (w4) of the width of the first extended insulating module 500 along the first direction to the width of the first welding ribbon 200 is 1.05≤w4≤2. More preferably, a ratio (w3) of the width of the second extended insulating module 500 along the first direction to the width of the first busbar 30 is 1.5≤w3≤2.5, and a ratio (w4) of the width of the first extended insulating module 500 along the first direction to the width of the first welding ribbon 200 is 1.2≤w4≤2.

[0126] As an optional embodiment, the second extended insulating module 500 is an insulating block or an insulating strip, or is made of insulating adhesive, but is not limited thereto. The second extended insulating module 500 provides insulation between the welding ribbon and the adjacent secondary grid lines. The second extended insulating module adopts a modular design, which has good insulation effect and improves the reliability of the battery string.

[0127] Furthermore, the present invention also includes a gate line insulation module 600, which is arranged at the first gate line 10 near the second main grid 40 to insulate the first gate line 10 from the second main grid 40 and the second welding strip 300; and / or, the gate line insulation module 600 is arranged at the second gate line 20 near the first main grid 30 to insulate the second gate line 20 from the first main grid 30 and the first welding strip 200. The first extended insulation module 400 and the gate line insulation module form an array distribution, which can further improve the reliability of the battery string.

[0128] Example 3

[0129] refer to Figure 12-16, this embodiment provides a back-contact solar cell string, comprising:

[0130] At least two battery cells 100, each of which includes alternating first polarity regions 60 and second polarity regions 70, a first grid line 10 for collecting the first polarity region, a second grid line 20 for collecting the second polarity region, a first main grid 30 connected to the first grid line, the first main grid 30 including a first edge main grid 31 provided on a side of the back contact cell near the first edge; a second main grid 40 connected to the second grid line, the second main grid 40 including a second edge main grid 41 provided on a side of the back contact cell near the second edge; the first grid line 10 includes a first extended grid line 11 connected to an end of the first main grid 30, the first extended grid line 11 extending along a first direction to a preset position of the first edge and / or the second edge to form a first grid line protrusion 12; the second grid line 20 includes a second extended grid line 21 connected to an end of the second main grid 40, the second extended grid line 21 extending along the first direction to a preset position of the first edge and / or the second edge to form a second grid line protrusion 22;

[0131] A first welding ribbon 200, which is used to connect the first busbar 30 of one cell and the second busbar 40 of an adjacent cell;

[0132] A second welding ribbon 300, which is used to connect the second busbar 40 of one cell to the first busbar 30 of an adjacent cell;

[0133] The first extending insulating module 400 is disposed in the contact area between the second soldering ribbon 300 and the first extended gate line 11 , so as to provide an insulated connection between the second soldering ribbon 300 and the first extended gate line 11 .

[0134] The second extending insulating module 500 is disposed in the contact area between the first soldering ribbon 200 and the second extending gate line 21 to provide an insulated connection between the first soldering ribbon 200 and the second extending gate line 21 .

[0135] The utility model extends the auxiliary grid line to the GAP area at the edge, and utilizes the first grid line protrusion 12 formed by extending the first extended grid line 11, which can effectively increase the current collection capacity of the area, improve the carrier collection efficiency, effectively reduce the efficiency loss in the edge area, and improve the efficiency of the battery cell.

[0136] In this embodiment, the first busbar 30 is a segmented busbar, wherein the first busbar 30 includes a plurality of first segmented busbars 30A, and the first gate lines 10 include a plurality of first extended gate lines 11 connected to the ends of the first segmented busbars 30A. Each first extended gate line 11 passes through all first segmented busbars 30A arranged along the first direction and extends along the first direction to a predetermined position at the second edge to form a first gate line protrusion 12. The first segmented busbars 30A and the first gate lines 10 are connected as a whole via the first extended gate lines 11. Figure 13-14 In the illustrated embodiment, with the dotted line L1 as the boundary, the first extended gate line 11 extends along the first direction to a predetermined position of the second edge to form a first gate line protrusion 12 .

[0137] The first segmented main gate 30A is connected to the first gate line 10 as a whole through the first extended gate line 11, forming a gate line structure in which the same polarity gate lines and the main gate are connected, constructing a multi-channel collection path, further providing more collection paths for the gate line current. When a short circuit, cold solder joint, etc. occurs in a certain gate line or welding point, current can still be collected through other paths, thereby improving the reliability of current collection.

[0138] In addition, after connecting the same polarity grid lines and the main grid corresponding to each pad point in the direction parallel to the same grid line as a whole, when welding with the welding ribbon, the pad points in the same polarity area can also be connected through the welding ribbon, so that more same polarity grid lines on the battery cell are connected into a whole, further reducing the risk of short circuit and cold welding, and improving the reliability of current collection.

[0139] The second gate line 20 includes a second extended gate line 21 connected to the end of the second main grid 40. The second extended gate line 21 extends along the first direction to a predetermined position of the first edge and / or the second edge to form a second gate line protrusion 22. The present invention extends the auxiliary gate line to the gap area at the edge. The second gate line protrusion 22 formed by the second extended gate line 21 can effectively increase the current collection capacity in this area, improve the carrier collection efficiency, effectively reduce the efficiency loss in the edge area, and improve the efficiency of the solar cell.

[0140] In this embodiment, the second busbar 40 is a segmented busbar, wherein the second busbar 40 includes a plurality of second segmented busbars 40A, and the second gate lines 20 include a plurality of second extended gate lines 21 connected to the ends of the second segmented busbars 40A. Each second extended gate line 21 passes through all the second segmented busbars 40A arranged along the first direction and extends along the first direction to a predetermined position at the first edge to form a second gate line protrusion 22. The second segmented busbars 40A and the second gate lines 20 are connected as a whole via the second extended gate lines 21. Figure 13-14In the illustrated embodiment, with the dotted line L1 as the boundary, the second extended gate line 21 extends along the first direction to a predetermined position of the first edge to form a second gate line protrusion 22 .

[0141] The second segmented main gate 40A is connected to the second gate line 20 through the second extended gate line 21, forming a gate line structure in which the same polarity gate lines and the main gate are connected, constructing a multi-channel collection path, further providing more collection paths for the gate line current. When a short circuit, cold solder joint, etc. occurs in a certain gate line or welding point, current can still be collected through other paths, thereby improving the reliability of current collection.

[0142] In addition, after connecting the same polarity grid lines and the main grid corresponding to each pad point in the direction parallel to the same grid line as a whole, when welding with the welding ribbon, the pad points in the same polarity area can also be connected through the welding ribbon, so that more same polarity grid lines on the battery cell are connected into a whole, further reducing the risk of short circuit and cold welding, and improving the reliability of current collection.

[0143] Regarding the relationship between extended gate lines and pad points, when the main gate is a segmented main gate, the number of same-sex extended gate lines is less than the number of all PAD points of the segmented main gate on the same straight line; the number of opposite-sex extended gate lines is less than the number of all PAD points.

[0144] In this embodiment, the first segmented busbar 30A is provided with third pad points 53, and the number of the second extended gate lines 21 is less than the number of the third pad points 53. Specifically, the number of the second extended gate lines 21 is less than the number of all third pad points 53 of the first segmented busbar 30A on the same straight line.

[0145] The second segmented busbar 40A is provided with fourth pad points 54. The number of the first extended gate lines 11 is less than the number of the fourth pad points 54. Specifically, the number of the first extended gate lines 11 is less than the number of all fourth pad points 54. The first extended gate lines 11 are heterodyne gate lines with opposite polarity to the silicon wafer, referred to as heterodyne extended gate lines, while the second extended gate lines 21 are homodyne gate lines with the same polarity as the silicon wafer, referred to as homodyne extended gate lines.

[0146] It should be noted that when the first extended gate line 11 includes a first edge extended gate line 11A and a first middle extended gate line 11B, the first middle extended gate line 11B is arranged between the fourth Pad points 54, and the first edge extended gate line 11A is arranged on the side of the back contact battery close to the third edge and / or the fourth edge. At this time, the number of first extended gate lines 11 is less than the number of all fourth Pad points 54.

[0147] When the first extended gate line 11 only includes the first middle extended gate line 11B, and the first gate line arranged on the side of the back contact battery close to the third edge and / or the fourth edge is not extended, the number of first extended gate lines 11 is less than the number of all fourth Pad points 54 of the second segmented main grid 40A on the same straight line.

[0148] It should also be noted that, in conjunction with the diagram, the first direction of this embodiment is the horizontal direction, and the second direction is the vertical direction. The first edge is the edge parallel to the first main grid 30 and is located on the right side of the solar cell. The second edge is the edge parallel to the first main grid 30 and is located on the left side of the solar cell. The third edge and the fourth edge are respectively parallel to the two edges of the first grid line 10 and are located on the upper and lower sides of the solar cell.

[0149] Further, if Figure 15 As shown, compared with the first and second embodiments, in this embodiment, the first polarity extension region 61 runs through the back side of the back-contact cell, the first extended gate line 11 runs through the first segmented busbar 30A, and the first extended gate line 11 is fully connected to the first polarity extension region 61. The second polarity extension region 71 runs through the back side of the back-contact cell, the second extended gate line 21 runs through the second segmented busbar 40A, and the second extended gate line 21 is fully connected to the second polarity extension region 71.

[0150] It should be noted that the first extended gateline 11 is fully connected to the first polarity extension region 61, and the second extended gateline 21 is fully connected to the second polarity extension region 71. The term "fully connected" means fully connected. Because the first polarity extension region and the second polarity extension region extend across the back of the back-contact battery, the first extended gateline extends through the first segmented busbar, and the second extended gateline extends through the second segmented busbar. The first extended gateline is fully connected to the first polarity extension region, and the second extended gateline is fully connected to the second polarity extension region. This allows for current collection across the entire region, improving carrier collection efficiency.

[0151] Preferably, if Figure 16 As shown, the width of the first extended insulating module 400 along the first direction is greater than the width of the second main grid 40, and greater than the width of the second welding strip 300; the width of the second extended insulating module 500 along the first direction is greater than the width of the first main grid 30, and greater than the width of the first welding strip 200, which is conducive to achieving reliable insulation between the welding strip and the adjacent auxiliary grid line, avoiding insulation failure caused by improper operation during the welding process, and improving the reliability of the battery string.

[0152] Preferably, a ratio w1 of the width of the first extended insulating module 400 along the first direction to the width of the second main grid 40 is 1.1≤w1≤3, and a ratio w2 of the width of the first extended insulating module 400 along the first direction to the width of the second welding ribbon 40 is 1.05≤w2≤2. More preferably, a ratio w1 of the width of the first extended insulating module 400 along the first direction to the width of the second main grid 40 is 1.5≤w1≤2.5, and a ratio w2 of the width of the first extended insulating module 400 along the first direction to the width of the second welding ribbon 300 is 1.2≤w2≤2.

[0153] Preferably, a ratio (w3) of the width of the second extended insulating module 500 along the first direction to the width of the first busbar 30 is 1.1≤w3≤3, and a ratio (w4) of the width of the first extended insulating module 500 along the first direction to the width of the first welding ribbon 200 is 1.05≤w4≤2. More preferably, a ratio (w3) of the width of the second extended insulating module 500 along the first direction to the width of the first busbar 30 is 1.5≤w3≤2.5, and a ratio (w4) of the width of the first extended insulating module 500 along the first direction to the width of the first welding ribbon 200 is 1.2≤w4≤2.

[0154] As an optional embodiment, the first extended insulating module 400 is an insulating block or strip, or is made of insulating adhesive; the second extended insulating module 500 is also an insulating block or strip, or is made of insulating adhesive, but is not limited thereto. The second extended insulating module 500 provides insulation between the solder ribbon and the adjacent secondary grid lines. The modular design of the second extended insulating module provides excellent insulation and improves the reliability of the battery string.

[0155] Furthermore, the present invention also includes a gate line insulation module 600, which is arranged at the first gate line 10 near the second main grid 40 to insulate the first gate line 10 from the second main grid 40 and the second welding strip 300; and / or, the gate line insulation module 600 is arranged at the second gate line 20 near the first main grid 30 to insulate the second gate line 20 from the first main grid 30 and the first welding strip 200. The first extended insulation module 400 and the gate line insulation module form an array distribution, which can further improve the reliability of the battery string.

[0156] Example 4

[0157] In order to better increase the effective power generation area of ​​the silicon wafer, generate more photogenerated carriers, increase the short-circuit current, and thus effectively improve the battery conversion efficiency. Based on the third embodiment, the first extended gate lines 11 of the fourth embodiment are heterosexual gate lines with opposite polarity to the silicon wafer, referred to as heterosexual extended gate lines, and the second extended gate lines 21 are homosexual gate lines with the same polarity as the silicon wafer, referred to as homosexual extended gate lines. The number of the first extended gate lines 11 is greater than the number of the second extended gate lines 21, that is, the number of heterosexual extended gate lines is greater than the number of homosexual extended gate lines.

[0158] The present invention controls the number of electrodes corresponding to the one with a different polarity from the silicon wafer in the first polarity region and the second polarity region to be greater than the number of electrodes corresponding to the one with the same polarity as the silicon wafer in the first polarity region and the second polarity region, thereby controlling the total length of the electrodes corresponding to the one with a different polarity from the silicon wafer in the first polarity region and the second polarity region to be greater than the total length of the electrodes corresponding to the one with the same polarity as the silicon wafer in the first polarity region and the second polarity region, thereby effectively increasing the effective power generation area of ​​the silicon wafer, generating more photogenerated carriers, increasing the short-circuit current, and thus effectively improving the battery conversion efficiency.

[0159] Preferably, the first extended gate lines 11 are heterogeneous gate lines with opposite polarity to the silicon wafer, and the number is N1; the second extended gate lines 21 are homogeneous gate lines with the same polarity as the silicon wafer, and the number is N2, where N1 - N2 = (1 - 2). Compared to the second extended gate lines 21, the extra first extended gate lines 11 can be located at the edge or in the middle, and their location can be adjusted according to the electrode pattern design.

[0160] More preferably, the first extended gate lines 11 are heterogeneous gate lines with opposite polarity to the silicon wafer, and the number is N1; the second extended gate lines 21 are homogeneous gate lines with the same polarity as the silicon wafer, and the number is N2, N1-N2=2, and the first extended gate lines 11 are arranged at the two edges and the middle area of ​​the battery.

[0161] In this embodiment, the first extended gate lines 11 include first edge extended gate lines 11A and first middle extended gate lines 11B. The first middle extended gate lines 11B are located between the fourth pad points 54, and the first edge extended gate lines 11A are located on the side of the back contact cell close to the third edge and / or the fourth edge. The second extended gate lines 21 include second middle extended gate lines 21A, which are located between the third pad points 53. The number of the first extended gate lines 22 is greater than the number of the second extended gate lines 21.

[0162] Since the solar cell can be made of N-type silicon or P-type silicon, when the back contact cell is made of N-type silicon, the first polarity region is a P-type doped region, and the first extended gate line is a P-type gate line; the second polarity region is an N-type doped region, and the second extended gate line is an N-type gate line;

[0163] When the back contact cell is P-type silicon, the first polarity region is an N-type doped region, and the first extended gate line is an N-type gate line; the second polarity region is a P-type doped region, and the second extended gate line is a P-type gate line.

[0164] Preferably, when the back contact cell is N-type silicon, the first polarity region is a P-type doped region, and the total length of all P-type gate lines is greater than the total length of all N-type gate lines;

[0165] When the back contact cell is P-type silicon, the first polarity region is an N-type doped region, and the total length of all N-type gate lines is greater than the total length of all P-type gate lines.

[0166] Further preferably, when the back contact cell is N-type silicon, the first polarity region is a P-type doped region, and the ratio a of the total length of all P-type gate lines to the total length of all N-type gate lines is 1<a≤1.2;

[0167] When the back contact cell is P-type silicon, the first polarity region is an N-type doped region, and the ratio b of the total length of all N-type gate lines to the total length of all P-type gate lines is 1<b≤1.2.

[0168] Within this range, it is possible to better balance the collection of electron-hole pairs while ensuring sufficient effective power generation area.

[0169] Exemplarily, when the back contact cell is N-type silicon, the ratio a of the total length of all P-type gate lines to the total length of all N-type gate lines is 1.001, 1.002, 1.005, 1.008, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19 or 1.2, but is not limited thereto.

[0170] Exemplarily, when the back contact cell is P-type silicon, the first polarity region is an N-type doped region, and the ratio b of the total length of all N-type gate lines to the total length of all P-type gate lines is 1.001, 1.002, 1.005, 1.008, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19 or 1.2, but is not limited thereto.

[0171] When a or b is less than or equal to 1, the effective power generation area is insufficient. When a or b is greater than 1.2, it is difficult to balance the collection of electron-hole pairs, affecting the battery conversion efficiency.

[0172] Example 5

[0173] Based on the fourth embodiment, the first extended gate lines 11 of the fifth embodiment are heterodyne gate lines with a polarity opposite to that of the silicon wafer, the second extended gate lines 21 are homodyne gate lines with a polarity identical to that of the silicon wafer, and the number of the first extended gate lines 22 is greater than the number of the second extended gate lines 21. Furthermore, the first polarity region has a polarity opposite to that of the silicon wafer, while the second polarity region has a polarity identical to that of the silicon wafer. The electrical conductivities of the silicon wafer, the first polarity region, and the second polarity region increase in sequence.

[0174] The utility model realizes a larger potential gradient between the first polarity region through the silicon wafer and then to the second polarity region by limiting the relationship between the number and length of the gate lines and the conductivity of the polarity regions, thereby strengthening the separation of photogenerated electron-hole pairs, and the collected charges can be transferred more quickly to the metal collection electrode corresponding to the metal gate line, and can effectively reduce the series resistance, reduce the power loss inside the battery, and improve the fill factor.

[0175] For example, the silicon wafer is N-type silicon, the first polarity region is a P-type doped layer, and the second polarity region is an N-type doped layer. By controlling the conductivity of the N-type silicon wafer, the P-type doped layer, and the N-type doped layer to increase in sequence, a larger potential gradient is achieved from the P-type doped layer through the silicon wafer to the N-type doped layer, thereby enhancing the separation of photogenerated electron-hole pairs. Among them, the one of the N-type doped layer and the P-type doped layer with the same polarity as the silicon wafer forms a high-low junction with the silicon wafer, and the one of the N-type doped layer and the P-type doped layer with a different polarity from the silicon wafer forms a pn junction with the silicon wafer. The larger potential gradient is conducive to the rapid entry of electrons into the N-type doped layer and the rapid entry of holes into the P-type doped layer, and the collected charges can be transmitted more quickly to the metal collection electrode corresponding to the metal grid line, and can effectively reduce the series resistance, reduce the power loss inside the battery, and improve the fill factor; at the same time, by controlling the total length of the electrode corresponding to the one of the N-type doped layer and the P-type doped layer with a different polarity from the silicon wafer to be longer than the total length of the electrode corresponding to the one of the N-type doped layer and the P-type doped layer with the same polarity as the silicon wafer, the effective power generation area of ​​the silicon wafer is increased, more photogenerated carriers are generated, the short-circuit current is increased, and the battery conversion efficiency is effectively improved.

[0176] Example 6

[0177] Based on the fourth embodiment, the first extended gate lines 11 of the sixth embodiment are heterodyne gate lines with opposite polarity to the silicon wafer, the second extended gate lines 21 are homodyne gate lines with the same polarity as the silicon wafer, and the number of the first extended gate lines 22 is greater than the number of the second extended gate lines 21. Furthermore, the first polarity region has an opposite polarity to the silicon wafer, while the second polarity region has the same polarity as the silicon wafer. The electrical conductivities of the silicon wafer, the first polarity region, and the second polarity region increase in sequence, and the width of the second polarity region is greater than the width of the first polarity region.

[0178] The utility model realizes a larger potential gradient between the first polarity region through the silicon wafer and then to the second polarity region by limiting the relationship between the number and length of the gate lines and the conductivity and width of the polarity regions, thereby strengthening the separation of photogenerated electron-hole pairs, and the collected charges can be transmitted more quickly to the metal collection electrode corresponding to the metal gate line, and can effectively reduce the series resistance, reduce the power loss inside the battery, and improve the fill factor.

[0179] For example, the silicon wafer is N-type silicon, the first polarity region is a P-type doped layer, and the second polarity region is an N-type doped layer. By controlling the conductivity of the N-type silicon wafer, the P-type doped layer, and the N-type doped layer to increase in sequence, a larger potential gradient is achieved from the P-type doped layer through the silicon wafer to the N-type doped layer, thereby enhancing the separation of photogenerated electron-hole pairs. Among them, the one of the N-type doped layer and the P-type doped layer with the same polarity as the silicon wafer forms a high-low junction with the silicon wafer, and the one of the N-type doped layer and the P-type doped layer with a different polarity from the silicon wafer forms a pn junction with the silicon wafer. The larger potential gradient is conducive to the rapid entry of electrons into the N-type doped layer and the rapid entry of holes into the P-type doped layer, and the collected charges can be transmitted more quickly to the metal collection electrode corresponding to the metal grid line, and can effectively reduce the series resistance, reduce the power loss inside the battery, and improve the fill factor; at the same time, by controlling the total length of the electrode corresponding to the one of the N-type doped layer and the P-type doped layer with a different polarity from the silicon wafer to be longer than the total length of the electrode corresponding to the one of the N-type doped layer and the P-type doped layer with the same polarity as the silicon wafer, the effective power generation area of ​​the silicon wafer is increased, more photogenerated carriers are generated, the short-circuit current is increased, and the battery conversion efficiency is effectively improved.

[0180] Due to the higher conductivity of the N-type doped layer compared to the P-type doped layer, the N-type doped layer has a stronger lateral transmission capability than the P-type doped layer, allowing for a greater transmission distance. Therefore, by using a low-concentration doped silicon wafer and setting the width of the N-type doped layer to be greater than the width of the P-type doped layer, carrier transmission distances can be matched based on the corresponding lateral transmission capabilities of the two, balancing current collection to achieve a lower series resistance and a higher fill factor, further improving conversion efficiency. At the same time, because the highly doped N-type doped layer has better passivation characteristics than the P-type doped layer, by reducing the width of the P-type doped layer and increasing the width of the N-type doped layer, the proportion of the passivation contact area of ​​the N-type polysilicon material layer is increased, which can improve the overall passivation level of the battery and reduce the recombination loss, further improving conversion efficiency.

[0181] Example 7

[0182] A back-contact cell assembly comprises the back-contact solar cell string described in the first to sixth embodiments above.

[0183] In the back-contact solar cell string provided in this embodiment, the utility model extends the secondary grid lines to the GAP region at the edge. Utilizing the grid line protrusion formed by the extension of the first extended grid lines, this effectively increases the current collection capacity in this region, improves carrier collection efficiency, and effectively reduces efficiency losses in the edge regions of the first and / or second edges, thereby improving the efficiency of the cell. The first extended insulation module provides insulation between the solder ribbon and the adjacent secondary grid lines. The first extended insulation module adopts a modular design, which provides good insulation and improves the reliability of the cell string.

[0184] Example 8

[0185] A back-contact battery system includes the back-contact battery assembly of the seventh embodiment.

[0186] In the back-contact solar cell string provided in this embodiment, the utility model extends the secondary grid lines to the GAP region at the edge. Utilizing the grid line protrusion formed by the extension of the first extended grid lines, this effectively increases the current collection capacity in this region, improves carrier collection efficiency, and effectively reduces efficiency losses in the edge regions of the first and / or second edges, thereby improving the efficiency of the cell. The first extended insulation module provides insulation between the solder ribbon and the adjacent secondary grid lines. The first extended insulation module adopts a modular design, which provides good insulation and improves the reliability of the cell string.

[0187] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A back contact solar cell string, characterized in that: include: At least two solar cells, each of the solar cells including alternating first polarity regions and second polarity regions, a first grid line for collecting the first polarity regions, a second grid line for collecting the second polarity regions, and a first busbar connected to the first grid line and a second busbar connected to the second grid line, wherein the first grid line includes a first extended grid line connected to an end of the first busbar, the first extended grid line extending along a first direction to a predetermined position of the first edge and / or the second edge to form a first grid line protrusion; A first welding ribbon, wherein the first welding ribbon is used to connect the first busbar of a solar cell and the second busbar of an adjacent solar cell; A second welding ribbon, wherein the second welding ribbon is used to connect the second main grid of a solar cell and the first main grid of an adjacent solar cell; The first extending insulating module is provided in a contact area between the second welding strip and the first extending gate line, so as to insulate the second welding strip from being connected to the first extending gate line.

2. The back contact solar cell string according to claim 1, wherein: A width of the first extended insulating module along the first direction is greater than a width of the second main grid and greater than a width of the second welding strip.

3. The back contact solar cell string according to claim 2, characterized in that: A ratio w1 of the width of the first extending insulating module along the first direction to the width of the second main grid is 1.1≤w1≤3, and a ratio w2 of the width of the first extending insulating module along the first direction to the width of the second welding strip is 1.05≤w2≤2.

4. The back-contact solar cell string according to any one of claims 1 to 3, characterized in that: It also includes a gate line insulation module, which is arranged at the first gate line near the second main grid to insulate the first gate line from the second main grid and the second welding strip; and / or, the gate line insulation module is arranged at the second gate line near the first main grid to insulate the second gate line from the first main grid and the first welding strip.

5. The back contact solar cell string according to claim 1, wherein: The second main grid includes a second edge main grid and other second main grids arranged on the side of the back contact battery close to the second edge. The length of the second edge main grid along the second direction is less than the length of the other second main grids. The first extended grid line extends along the first direction to a preset position of the second edge to form a first grid line protrusion.

6. The back contact solar cell string according to claim 5, characterized in that: The first gate line protrusion protrudes from the second edge bus bar, or is flush with the second edge bus bar.

7. The back-contact solar cell string according to claim 1, wherein: The length of the first gate line protrusion is d1, and the distance between the first gate line protrusion and the second edge is d2, wherein d1:d2=(2-5):(1-2).

8. The back contact solar cell string according to claim 7, characterized in that: The length d1 of the first gate line protrusion is 300-2000 μm.

9. The back contact solar cell string according to claim 1, wherein: The second gate line includes a second extended gate line connected to an end of the second main gate, and the second extended gate line extends along the first direction to a predetermined position of the first edge and / or the second edge to form a second gate line protrusion.

10. The back contact solar cell string according to claim 9, characterized in that: The device further includes a second extending insulating module, which is disposed in a contact area between the first welding strip and the second extending gate line to insulate the first welding strip from the second extending gate line.

11. The back contact solar cell string according to claim 10, characterized in that: A width of the second extended insulating module along the first direction is greater than a width of the first main grid and greater than a width of the first welding strip.

12. The back contact solar cell string according to claim 11, characterized in that: A ratio w3 of the width of the second extending insulating module along the first direction to the width of the first main grid is 1.1≤w3≤3, and a ratio w4 of the width of the first extending insulating module along the first direction to the width of the first welding strip is 1.05≤w4≤2.

13. The back-contact solar cell string according to claim 9, characterized in that: The first extending insulating module and the second extending insulating module are insulating blocks or insulating strips.

14. The back-contact solar cell string according to claim 9, characterized in that: The first main grid includes a first edge main grid and other first main grids arranged on the side of the back contact battery close to the first edge, the length of the first edge main grid along the second direction is less than the length of the other first main grids, and the second extended grid line extends along the first direction to a preset position of the first edge to form a second grid line protrusion.

15. The back contact solar cell string according to claim 14, characterized in that: The second gate line protrusion protrudes from the first edge bus bar, or is flush with the first edge bus bar.

16. The back-contact solar cell string according to claim 9, characterized in that: The length of the second gate line protrusion is d3, and the distance between the second gate line protrusion and the first edge is d4, wherein d3:d4=(2-5):(1-2).

17. The back-contact solar cell string according to claim 16, characterized in that: The length d3 of the second gate line protrusion is 300-2000 μm.

18. The back-contact solar cell string according to claim 9, characterized in that: The first main grid is provided with first Pad points, and the number of the second extended gate lines is less than the number of the first Pad points; the second main grid is provided with second Pad points, and the number of the first extended gate lines is less than the number of the second Pad points.

19. The back-contact solar cell string according to claim 9, characterized in that: The first main gate is a segmented main gate, wherein the first main gate includes several first segmented main gates, and the first gate line includes several first extended gate lines connected to the ends of the first segmented main gates. Each of the first extended gate lines passes through all the first segmented main gates arranged along the first direction and extends along the first direction to a preset position of the second edge to form a first gate line protrusion.

20. The back contact solar cell string according to claim 19, characterized in that: The first segmented main gate and the first gate line are connected as one through a first extended gate line.

21. The back-contact solar cell string according to claim 19, wherein: The second main gate is a segmented main gate, wherein the second main gate includes several second segmented main gates, and the second gate line includes several second extended gate lines connected to the ends of the second segmented main gates. Each of the second extended gate lines passes through all the second segmented main gates arranged along the first direction and extends along the first direction to a preset position of the first edge to form a second gate line protrusion.

22. The back-contact solar cell string according to claim 21, characterized in that: The second segmented main gate and the second gate line are connected as one through a second extended gate line.

23. The back-contact solar cell string according to claim 21, characterized in that A third Pad point is provided on the first segmented main gate, and the number of the second extended gate lines is less than the number of the third Pad point; a fourth Pad point is provided on the second segmented main gate, and the number of the first extended gate lines is less than the number of the fourth Pad point.

24. The back-contact solar cell string according to claim 9 or 21, characterized in that: The first extended gate lines are heterogeneous gate lines with opposite polarity to the silicon wafer, and the second extended gate lines are homogeneous gate lines with the same polarity as the silicon wafer. The number of the first extended gate lines is greater than the number of the second extended gate lines.

25. The back-contact solar cell string according to claim 24, characterized in that: The first extended gate lines are heterogeneous gate lines with opposite polarity to the silicon wafer, and the number is N1; the second extended gate lines are homogeneous gate lines with the same polarity as the silicon wafer, and the number is N2, where N1-N2=(1-2).

26. The back-contact solar cell string according to claim 25, characterized in that: When the back contact cell is N-type silicon, the first polarity region is a P-type doped region, and the first extended gate line is a P-type gate line; the second polarity region is an N-type doped region, and the second extended gate line is an N-type gate line; When the back contact cell is P-type silicon, the first polarity region is an N-type doped region, and the first extended gate line is an N-type gate line; the second polarity region is a P-type doped region, and the second extended gate line is a P-type gate line.

27. The back-contact solar cell string according to claim 26, characterized in that: When the back contact cell is N-type silicon, the first polarity region is a P-type doped region, and the total length of all P-type gate lines is greater than the total length of all N-type gate lines; When the back contact cell is made of P-type silicon, the first polarity region is an N-type doped region, and the total length of all N-type gate lines is greater than the total length of all P-type gate lines.

28. The back-contact solar cell string according to claim 27, characterized in that: When the back contact cell is N-type silicon, the first polarity region is a P-type doped region, and the ratio a of the total length of all P-type gate lines to the total length of all N-type gate lines is 1<a≤1.2; When the back contact cell is P-type silicon, the first polarity region is an N-type doped region, and the ratio b of the total length of all N-type gate lines to the total length of all P-type gate lines is 1<b≤1.

2.

29. The back-contact solar cell string according to claim 23, wherein: The first extended gate lines include first edge extended gate lines and first middle extended gate lines. The first middle extended gate lines are arranged between the fourth Pad points, and the first edge extended gate lines are arranged on the side of the back contact battery close to the third edge and / or fourth edge.

30. The back-contact solar cell string according to claim 23, wherein: The second extended gate lines include second middle extended gate lines, and the second middle extended gate lines are arranged between the third Pad points.

31. The back-contact solar cell string according to claim 21, wherein: The first polarity region includes a first polarity extension region, the first polarity extension region extends along a first direction to form a first polarity protrusion, and the first extended gate line is electrically connected to the first polarity region; And / or, the second polarity region includes a second polarity extension region, the second polarity extension region extends along the first direction to form a second polarity protrusion, and the second extended gate line is electrically connected to the second polarity region.

32. The back contact solar cell string according to claim 31, characterized in that The first polarity extension region runs through the back side of the back-contact battery, the first extended gate line runs through the first segmented main gate, and the first extended gate line and the first polarity extension region are fully connected; the second polarity extension region runs through the back side of the back-contact battery, the second extended gate line runs through the second segmented main gate, and the second extended gate line and the second polarity extension region are fully connected.

33. The back-contact solar cell string according to claim 31, characterized in that The first polarity extension region and / or the second polarity extension region is provided with a first opening.

34. The back-contact solar cell string according to claim 33, characterized in that The width of the first opening is 150-450 nm.

35. A back contact battery assembly, characterized in that: It comprises the back-contact solar cell string according to any one of claims 1 to 34.

36. A back contact battery system, characterized in that: It includes the back contact battery assembly as described in claim 35.

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