Back contact battery piece, preparation method thereof and photovoltaic module

Abstract

The invention provides a back contact battery piece, a preparation method thereof and a photovoltaic module, and relates to the field of photovoltaic technology. The back contact battery piece comprises a battery body; the battery body comprises current collection doped regions including a first current collection doped region and a second current collection doped region which extend along a first direction and are alternately distributed at intervals along a second direction; the confluence doping region comprises a first confluence doping region and a second confluence doping region which extend along the second direction and are alternately distributed at intervals along the first direction; in the first direction, current collection doped regions with at least one polarity are arranged on the two sides of a positioning region located between the adjacent first confluence doped region and second confluence doped region, and a first isolation region is arranged on at least one side of the current collection doped region with at least one polarity and the positioning region in the first direction. The positioning effect is more accurate, and the problem of poor carrier collection caused by a dead zone can be solved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a back contact cell sheet and a preparation method thereof, and a photovoltaic module. Background Art

[0002] The back-contact cell can make full use of sunlight due to its structure without grid lines on the light-facing side, making it more efficient. In addition, the structure without grid lines on the light-facing side makes the appearance of the component end more beautiful, so it has broad application prospects.

[0003] The design of the busbar area, collector area and isolation area of ​​different polarities in the back contact cell is relatively complex. How to achieve high-precision design has become a technical challenge. Currently, the above complex design is mainly achieved by adding positioning points.

[0004] In the existing technology, positioning is mainly performed through cross marks, dots and battery edge grips, however, the current positioning method has the problem of poor positioning effect. Summary of the invention

[0005] The present invention provides a back-contact cell sheet and a preparation method thereof and a photovoltaic module, aiming to solve the problem of poor positioning effect in existing back-contact cells.

[0006] In a first aspect of the present invention, there is provided a back contact battery sheet, comprising: a battery body; the battery body comprises:

[0007] The collector doping region comprises a first collector doping region and a second collector doping region, wherein the first collector doping region and the second collector doping region extend along a first direction and are alternately spaced along a second direction; the first direction is different from the second direction; and the first collector doping region and the second collector doping region have different doping types;

[0008] A bus doping region, comprising a first bus doping region and a second bus doping region, wherein the first bus doping region and the second bus doping region extend along the second direction and are alternately spaced and distributed along the first direction; the first bus doping region and the second bus doping region have different doping types; the first collector doping region and the first bus doping region have the same polarity, and the second collector doping region and the second bus doping region have the same polarity; at least a portion of the first collector doping region intersects with the first bus doping region, and at least a portion of the second collector doping region intersects with the second bus doping region;

[0009] In the first direction: a positioning region located between adjacent first bus doping regions and second bus doping regions, and both sides of the positioning region have the collector doping regions of at least one polarity, and the collector doping region of at least one polarity in the first direction has a first isolation region from at least one side of the positioning region;

[0010] In the second direction: both sides of the positioning region have collector doping regions of at least one polarity, and both sides of the collector doping region of at least one polarity and the positioning region in the second direction have second isolation regions.

[0011] In the present application, in the first direction, the positioning area is designed to be located between the adjacent first bus doping area and the second bus doping area. When the back contact cell also includes a bus grid line, the bus grid line is located on the bus doping area, that is, the positioning area is designed to be located between the adjacent first bus grid line and the second bus grid line, which can effectively solve the positioning problem between the grid line and the doping area and improve the positioning accuracy. In the first direction, both sides of the positioning area have collector doping areas of at least one polarity, which can reduce the area of ​​the dead zone and improve the current collection efficiency. In the second direction, both sides of the positioning area have collector doping areas of at least one polarity, and both sides of the collector doping area and the positioning area have a second isolation area, and then the positioning area is separated from the second direction, further improving the positioning accuracy.

[0012] Optionally, the bus doping region is only arranged at at least one end of the battery body along the second direction, and in the second direction, there is a gap between the bus doping region and the positioning region.

[0013] Optionally, in the first direction: both sides of the positioning area have collector doping regions with opposite polarities, and both sides of the collector doping regions with opposite polarities in the first direction and the positioning area have first isolation regions, and the first isolation region and the second isolation region are enclosed into a continuous isolation region. In the first direction, both sides of the positioning area have collector doping regions with opposite polarities, which can solve the problem of poor carrier collection caused by the dead zone. The first isolation region and the second isolation region are enclosed into a continuous isolation region to facilitate the accuracy of grasping and positioning.

[0014] Optionally, the back contact cell further comprises:

[0015] In the collector doping regions with opposite polarities in the first direction, the first collector gate line located on the first collector doping region, and the second collector gate line located on the second collector doping region, the first collector gate line and the second collector gate line located on both sides of the positioning region are spaced apart from the positioning region.

[0016] Optionally, in the first direction: the size of the positioning region is L1, the distance between adjacent collector doping regions with opposite polarities in the first direction is L2; ​​L2>L1>L2 / 2; and / or,

[0017] In the second direction, the size of the positioning area is L3, and the distance between two adjacent collector doping regions with the same polarity is L4; L4>L3>L4 / 2.

[0018] Optionally, a third isolation region is provided between the adjacent first collector doping region and the second collector doping region;

[0019] In the second direction, the size of the third isolation region is L5;

[0020] In the first direction, a size of the first isolation area located on one side of the positioning area is L6;

[0021] In the second direction, a size of the second isolation area located on one side of the positioning area is L7;

[0022] 1.5×L5>L6>L5; and / or,

[0023] L5=L7.

[0024] Optionally, the back contact battery sheet further comprises: a positioning electrode point, the orthographic projection of the positioning electrode point on the battery body is located in the positioning area; in the second direction: the size of the positioning electrode point is L8, and the size of the positioning area is L3;

[0025] 0.4×L3<L8<0.8×L3.

[0026] Optionally, in the first direction, both sides of the positioning region have the collector doping region with the same polarity; in the first direction, both sides of the collector doping region with the same polarity and the positioning region have the first isolation region, and the first isolation region and the second isolation region are enclosed into a continuous isolation area.

[0027] Optionally, the back contact cell further comprises:

[0028] In the collector doping regions with the same polarity in the first direction, the first collector gate line located on the first collector doping region, and the second collector gate line located on the second collector doping region, at least one of the first collector gate line or the second collector gate line extends from one side of the positioning region through the positioning region to the other side of the positioning region, and is continuously distributed on the collector doping regions with the same polarity in the first direction.

[0029] Optionally, in the second direction: both sides of the positioning region have the collector doping regions with the same polarity, and both sides of the collector doping regions with the same polarity and the positioning region in the second direction have the second isolation region.

[0030] Optionally, the positioning areas are axially symmetrically distributed in the back contact cell, and the axis of symmetry is parallel to the second direction.

[0031] Optionally, the positioning region is a first collector doping region or a second collector doping region;

[0032] The back contact cell has at least two positioning regions collinearly along the first direction; all the positioning regions collinearly along the first direction are first collector doping regions or second collector doping regions.

[0033] Optionally, the number of the positioning areas is 2 to 4.

[0034] Optionally, the area of ​​one of the positioning regions is 0.5 mm 2 Up to 1.5mm 2 .

[0035] Optionally, the positioning area is a P-type collector doping area.

[0036] Optionally, the back contact cell further comprises:

[0037] A first bus gate line located on the first bus doping region, and a second bus gate line located on the second bus doping region; at least part of the first collector gate line intersects with the first bus gate line, and at least part of the second collector gate line intersects with the second bus gate line.

[0038] Optionally, the back contact cell further comprises:

[0039] A plurality of electrode plates located on the busbar line; the plurality of electrode plates include: at least two positioning electrode plates corresponding to the positioning area and away from the geometric center of the back contact battery sheet; the shape of the positioning electrode plates is different from the shape of the remaining electrode plates;

[0040] At least two of the positioning electrode plates are axially symmetrically distributed in the back contact battery sheet, and the axis of symmetry is parallel to the second direction.

[0041] Optionally, the back contact cell sheet further comprises: insulating glue;

[0042] The insulating glue is at least located on the opposite-sex collector grid line that is adjacent to the bus grid line;

[0043] The orthographic projection of the insulating glue on the battery body is separated from the positioning area.

[0044] In a second aspect of the present invention, a back contact battery sheet is provided, comprising: a battery body; the battery body comprises: a plurality of battery cells and a partition area between adjacent battery cells, the battery cells comprising:

[0045] The collector doping region comprises a first collector doping region and a second collector doping region, wherein the first collector doping region and the second collector doping region extend along a first direction and are alternately spaced along a second direction, and the first direction is different from the second direction; and the first collector doping region and the second collector doping region have different doping types;

[0046] A bus doping region, comprising a first bus doping region and a second bus doping region, wherein the first bus doping region and the second bus doping region extend along the second direction and are alternately spaced along the first direction; the first bus doping region and the second bus doping region have different doping types; the first collector doping region and the first bus doping region have the same polarity, and the second collector doping region and the second bus doping region have the same polarity; at least a portion of the first collector doping region intersects with the first bus doping region, and at least a portion of the second collector doping region intersects with the second bus doping region;

[0047] In the first direction: a positioning region located between adjacent first bus doping regions and second bus doping regions, and both sides of the positioning region have the collector doping regions of at least one polarity, and the collector doping region of at least one polarity in the first direction has a first isolation region from at least one side of the positioning region;

[0048] In the second direction: both sides of the positioning region have collector doping regions of at least one polarity, and both sides of the collector doping region of at least one polarity and the positioning region in the second direction have second isolation regions;

[0049] All the positioning areas are symmetrical about the center of the battery body.

[0050] Optionally, the positioning region passes through a center line between the adjacent first bus doping region and the second bus doping region.

[0051] Optionally, the back-contact cell sheet is sliced ​​along the dividing area to obtain any of the aforementioned back-contact cell sheets.

[0052] A third aspect of the present invention provides a method for preparing a back contact cell, comprising:

[0053] Providing a silicon substrate; the silicon substrate comprises a first surface and a second surface opposite to each other;

[0054] forming a first doping layer on a first surface of the silicon substrate;

[0055] Part of the first doping layer is removed so that the first surface is partially exposed, and the remaining first doping layer includes: a plurality of first collector doping regions extending along the first direction and spaced apart along the second direction, and a plurality of first bus doping regions extending along the second direction and spaced apart along the first direction; at least a portion of the first collector doping regions intersects with the first bus doping regions; a portion of the plurality of first collector doping regions covers a positioning region, and the first doping layer around the positioning region is removed; wherein the first direction is different from the second direction;

[0056] forming a second doping layer on the exposed first surface and the remaining first doping layer; the first doping layer and the second doping layer have different doping types;

[0057] Removing a portion of the second doping layer so that the plurality of first collector doping regions and the plurality of first bus doping regions are exposed, forming first collector doping regions and second collector doping regions extending along the first direction and alternately spaced along the second direction, first bus doping regions and second bus doping regions extending along the second direction and alternately spaced along the first direction, and the positioning region, at least a portion of the second collector doping region and the second bus doping region intersect;

[0058] In the first direction: a positioning region located between adjacent first bus doping regions and second bus doping regions, and both sides of the positioning region have the collector doping regions of at least one polarity, and the collector doping region of at least one polarity in the first direction has a first isolation region from at least one side of the positioning region;

[0059] In the second direction: both sides of the positioning region have collector doping regions of at least one polarity, and both sides of the collector doping region of at least one polarity and the positioning region in the second direction have second isolation regions.

[0060] Optionally, the method further comprises: preparing multiple gate lines, wherein:

[0061] Taking the positioning area as a positioning point, performing a first gate line preparation and forming a positioning electrode point in the positioning area;

[0062] The positioning electrode points are used as positioning points to prepare the remaining grid lines.

[0063] Optionally, the partial area where the first doping layer is removed partially overlaps with the partial area where the second doping layer is removed, so that at least a partial area around the positioning area is exposed to the silicon substrate, and the exposed silicon substrate forms the first isolation area and the second isolation area.

[0064] A fourth aspect of the present invention provides a photovoltaic module, comprising: a back-contact cell according to any one of the preceding claims.

[0065] A fifth aspect of the present invention provides a photovoltaic module, comprising:

[0066] A plurality of back-contact battery cells; the back-contact battery cells include: a battery body, the battery body includes: a collector doping region, including a first collector doping region and a second collector doping region, the first collector doping region and the second collector doping region extend along a first direction and are alternately spaced along a second direction; the first direction is different from the second direction; the first collector doping region and the second collector doping region have different doping types;

[0067] The back contact cell further comprises: a collector grid line located on the cell body, the collector grid line comprising a first collector grid line located on the first collector doping region, and a second collector grid line located on the second collector doping region;

[0068] An interconnection member; the interconnection member electrically connects two adjacent back-contact battery sheets, one end of the interconnection member is electrically connected to the second collector grid line of one of the two adjacent back-contact battery sheets, and the other end of the interconnection member is electrically connected to the first collector grid line of the other of the two adjacent back-contact battery sheets;

[0069] The battery body also includes:

[0070] In the first direction: a positioning region located between adjacent interconnects, and both sides of the positioning region have the collector doping region of at least one polarity, and the collector doping region of at least one polarity in the first direction has a first isolation region with at least one side of the positioning region;

[0071] In the second direction: both sides of the positioning region have collector doping regions of at least one polarity, and both sides of the collector doping region of at least one polarity and the positioning region in the second direction have second isolation regions.

[0072] The above-mentioned back contact cell and its preparation method and photovoltaic module have the same or similar beneficial effects, and will not be described again here to avoid repetition. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0074] Figure 1 A schematic diagram of the partial structure of a first back contact cell in an embodiment of the present invention is shown;

[0075] Figure 2 A partial structural schematic diagram of a second back contact cell according to an embodiment of the present invention is shown;

[0076] Figure 3 A partial structural schematic diagram of a third back contact cell according to an embodiment of the present invention is shown;

[0077] Figure 4 A partial structural schematic diagram of a fourth back contact cell according to an embodiment of the present invention is shown;

[0078] Figure 5 A partial structural schematic diagram of a fifth back-contact solar cell in an embodiment of the present invention is shown;

[0079] Figure 6 A partial structural schematic diagram of a sixth back contact cell in an embodiment of the present invention is shown;

[0080] Figure 7 A partial structural schematic diagram of a seventh back-contact solar cell in an embodiment of the present invention is shown;

[0081] Figure 8 A comparison chart of positioning accuracy test results of different positioning methods is shown;

[0082] Fig. 9 A comparison diagram showing the test results of short-circuit current of back contact cells corresponding to positioning areas in different configurations;

[0083] Fig.10 A comparison chart of the test results of the short-circuit current of the back contact battery cells corresponding to the positioning areas of different areas is shown.

[0084] Description of the accompanying drawings:

[0085] 11-first collector doping region, 12-second collector doping region, 13-positioning region, 14-first isolation region, 15-third isolation region, 16-positioning electrode point, 17-second isolation region, 21-first collector grid line, 22-second collector grid line, 23-positioning electrode disk, 24-remaining electrode disks. DETAILED DESCRIPTION

[0086] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0087] The present invention provides a back contact cell. During normal operation of the back contact cell, the side that mainly receives light is the front side, and the back side is opposite to the front side. The back contact cell comprises: a cell body, which contains a PN junction that can separate carriers. Figures 1 to 7 The left-right direction is the first direction M, and the up-down direction is the second direction Q. Figures 1 to 4 The battery body includes: a collector doping region, including a first collector doping region 11 and a second collector doping region 12, the first collector doping region 11 and the second collector doping region 12 extend along a first direction M and are alternately spaced along a second direction Q. The first direction M is different from the second direction Q, and the angle between the two is not limited. For example, the first direction M and the second direction Q can be perpendicular. The number of the first collector doping region 11 and the second collector doping region 12 is not specifically limited. The first collector doping region 11 and the second collector doping region 12 have different doping types, one of which is an N-type collector doping region and the other is a P-type collector doping region.

[0088] The battery body also includes: a bus doping region, including a first bus doping region and a second bus doping region, the first bus doping region and the second bus doping region extend along the second direction Q and are alternately spaced along the first direction M, the first bus doping region and the second bus doping region have different doping types, one of which is an N-type bus doping region and the other is a P-type bus doping region. The first collector doping region 11 has the same doping type as the first bus doping region, and the second collector doping region 12 has the same doping type as the second bus doping region. At least part of the first collector doping region 11 intersects with the first bus doping region, and at least part of the second collector doping region 12 intersects with the second bus doping region. The width of the bus doping region can be greater than the width of the collector doping region, the direction where the width of the bus doping region is parallel to the first direction M, and the direction where the width of the collector doping region is parallel to the second direction Q, and the carriers in the first collector doping region can be collected to the first bus doping region, and the carriers in the second collector doping region can be collected to the second bus doping region.

[0089] Reference Figures 1 to 7, the battery body also includes: in the first direction M: a positioning area 13 located between the adjacent first current-collecting doping area and the second current-collecting doping area, the positioning area 13 is the first current-collecting doping area or the second current-collecting doping area. And in the first direction M, both sides of the positioning area 13 have current-collecting doping areas of at least one polarity, and the current-collecting doping area of ​​at least one polarity in the first direction M and at least one side of the positioning area 13 have a first isolation area 14, where one polarity refers to N-type or P-type. That is to say, in the first direction M, when the positioning area 13 is adjacent to both the first current-collecting doping area and the second current-collecting doping area, the positioning area 13 and at least one side of the adjacent first current-collecting doping area and the second current-collecting doping area have at least a first isolation area. Or, in the first direction M, when the positioning area 13 is only adjacent to the first current-collecting doping area, the positioning area 13 and at least one side of the adjacent first current-collecting doping area have a first isolation area. Alternatively, in the first direction M, when the positioning region 13 is adjacent only to the second collector doping region, the positioning region 13 and at least one side of the adjacent second collector doping region have a first isolation region. In the first direction M, the positioning region 13 is designed to be located between the adjacent first bus doping region and the second bus doping region. When the back contact cell also includes a bus grid line, the bus grid line is located on the bus doping region, that is, the positioning region 13 is designed to be located between the adjacent first bus grid line and the second bus grid line, which can effectively solve the problem of positioning between the grid line and the doping region and improve the positioning accuracy. The two sides of the positioning region in the first direction M have collector doping regions of at least one polarity, which can reduce the area of ​​the dead zone and improve the current collection efficiency.

[0090] In the second direction Q, both sides of the positioning region 13 have at least one collector doping region of polarity, and both sides of the at least one collector doping region of polarity and the positioning region in the second direction Q have second isolation regions 17, thereby realizing uniform collection of carriers on the entire surface, and realizing sufficient collection of carriers on both sides of the positioning region 13. One polarity here refers to N-type or P-type. That is to say, in the second direction Q, when the positioning region 13 is adjacent to both the first collector doping region and the second collector doping region, both sides of the positioning region 13 and the adjacent first collector doping region and the second collector doping region have second isolation regions. Alternatively, in the second direction Q, when the positioning region 13 is adjacent only to the first collector doping region, both sides of the positioning region 13 and the adjacent first collector doping region have second isolation regions. Alternatively, in the second direction Q, when the positioning region 13 is adjacent only to the second collector doping region, both sides of the positioning region 13 and the adjacent second collector doping region have second isolation regions. It should be noted that, in the second direction Q, a third isolation region 15 is provided between the adjacent first collector doping region and the second collector doping region, and the second isolation region 17 can partially overlap with the third isolation region 15, or the third isolation region 15 directly exists as the second isolation region, which can improve the patterning capacity and reduce the cost. Alternatively, the second isolation region 17 and the third isolation region 15 can also be separated, which is not specifically limited.

[0091] Optional, see Figures 1 to 4 , in the second direction Q, both sides of the positioning region 13 have collector doping regions with the same polarity, and both sides of the collector doping regions with the same polarity and the positioning region in the second direction Q have second isolation regions 17, thereby realizing uniform collection of carriers on the entire surface, and realizing sufficient collection of carriers on both sides of the positioning region 13, and the positioning region 13 is located in the middle area of ​​a collector doping region, and the process compatibility is better. For example, referring to Figures 1 to 4 , in the second direction Q, both sides of the positioning region 13 have first collector doping regions with the same polarity, and in the second direction Q, there is a second isolation region 17 between the first collector doping regions with the same polarity and the positioning region 13. A third isolation region 15 is provided between the adjacent first collector doping regions and the second collector doping regions, and the second isolation region 17 may partially overlap with the third isolation region 15, or the second isolation region 17 may overlap with the third isolation region 15 on one side, or the third isolation region 15 directly exists as the second isolation region, or the second isolation region 17 may be separated from the third isolation region 15, and no specific limitation is made to this.

[0092] Optional, see Figure 1In the first direction M, the two sides of the positioning region 13 have collector doping regions with opposite polarities, that is, in the first direction M, one side of the positioning region 13 has a first collector doping region, and the other side has a second collector doping region, or one side of the positioning region 13 has an N-type collector doping region, and the other side has a P-type collector doping region. In the first direction M, the collector doping regions with opposite polarities and both sides of the positioning region 13 have first isolation regions 14, and the first isolation regions 14 limit the positioning region 13 to a relatively independent region. For example, Figure 1 In the first direction M, the left side of the positioning region 13 has a first collector doping region 11, the right side of the positioning region 13 has a second collector doping region 12, a first isolation region 14 is provided between the positioning region 13 and the first collector doping region 11 on its left side, and a first isolation region 14 is provided between the positioning region 13 and the second collector doping region 12 on its right side. In the first direction M, both sides of the positioning region 13 have collector doping regions with opposite polarities, referring to Figure 1 , the collector grid line is arranged on the collector doping region, more specifically, the first collector grid line 21 is arranged on the first collector doping region 11, and the second collector grid line 22 is arranged on the second collector doping region 12, then in the first direction M, the two sides of the positioning region 13 have collector grid lines with opposite polarities, and the positioning region 13 is equivalent to a dead zone, which can solve the problem of poor carrier collection caused by the dead zone. In this case, the collector grid line may not be arranged on the positioning region 13.

[0093] Optionally, the first isolation region 14 here can be enclosed with the aforementioned second isolation region 17 to form a continuous isolation region, which is beneficial to the accuracy of grasping and positioning. Alternatively, the first isolation region 14 here can be enclosed with the aforementioned second isolation region 17 to form a continuous isolation region, or the first isolation region 14 can be separated from the aforementioned second isolation region 17, which can improve the patterning capacity and reduce the cost.

[0094] Optionally, the bus doping area is only arranged at at least one end of the battery body along the second direction Q, and in the second direction Q, there is a gap between the bus doping area and the positioning area 13, and the bus doping area in the middle area is removed, thereby reducing the shading area caused by the bus grid line. At the same time, the bus doping area is retained in the end area, which can reserve space for battery electrical interconnection and reduce the difficulty of welding. The positioning area is arranged in the middle area, which is convenient for the camera to capture the positioning area and accurately position it.

[0095] Optionally, the bus doping region is arranged at two end regions of the battery body along the second direction Q, and in the two end regions, the collector doping region is electrically connected to the bus doping region with the same polarity and electrically isolated from the bus doping region with the opposite polarity. There is an intermediate region between the two end regions, and the intermediate region is provided with collector doping regions that are continuously distributed along the first direction and alternately distributed along the second direction. The positioning region 13 is located in the intermediate region. In the second direction Q, there is a gap between the bus doping region and the positioning region 13. The bus doping region in the intermediate region is removed, which reduces the shading area caused by the bus grid line. At the same time, the bus doping region is retained in the end region, which can reserve space for electrical interconnection of the back contact battery cell and reduce the difficulty of welding. The positioning region 13 is arranged in the intermediate region, which is convenient for the camera to capture the positioning region 13 and accurately locate it.

[0096] Optionally, the shape of the positioning area 13 is not limited and can be any shape that is easy to identify, including a square, an irregular polygon, an irregular figure with a curved surface, etc. In particular, a square, especially a square or rectangular positioning area, is easier to be captured by the alignment device, thereby improving the accuracy of alignment recognition.

[0097] Optional, see Figure 1 , in the aforementioned first direction M: the size of the positioning area 13 is L1, and the distance between adjacent collector doping regions with opposite polarities in the aforementioned first direction M is L2, which is the distance between the endpoints of adjacent collector doping regions with opposite polarities in the aforementioned first direction M, L2>L1>L2 / 2, specifically, if L1 is too large, there is a risk of leakage, and if L1 is too small, the positioning effect is poor. Therefore, in the present application, L2>L1>L2 / 2 not only has a smaller risk of leakage but also has a better positioning effect.

[0098] For example, L1 can be 0.99L2, 0.97L2, 0.95L2, 0.9L2, 0.85L2, 0.8L2, 0.77L2, 0.7L2, 0.75L2, 0.6L2, 0.65L2, 0.55L2, 0.52L2, 0.51L2.

[0099] Optional, see Figure 2 In the second direction Q, the size of the positioning area 13 is L3, and the distance between two adjacent collector doping regions with the same polarity is L4, L4>L3>L4 / 2. Specifically, if L3 is too large, more fine gates will be interrupted, resulting in more dead zones. If L3 is too small, the positioning effect cannot be satisfied. L4>L3>L4 / 2 not only has high positioning accuracy, but also has fewer dead zones.

[0100] For example, L3 can be 0.99L4, 0.96L4, 0.95L4, 0.9L4, 0.85L4, 0.8L4, 0.78L4, 0.7L4, 0.75L4, 0.6L4, 0.65L4, 0.55L4, 0.52L4, and 0.51L4.

[0101] Optional, see Figures 1 to 4 In the second direction Q, there is a second isolation region 17 between the positioning region 13 and the adjacent collector doping region, and the positioning region 13 is set as a relatively independent region in the second direction Q. A third isolation region 15 is set between the adjacent first collector doping region 11 and the second collector doping region 12 to avoid internal short circuit of the battery cell. Figure 3 In the second direction Q, the size of the third isolation region 15 is L5. In the first direction M, the size of the first isolation region 14 located on one side of the positioning region 13 is L6. 1.5×L5>L6>L5, L6 is set appropriately, which can not only achieve a good isolation effect, but also avoid space waste.

[0102] For example, L6 can be 1.49L5, 1.4L5, 1.35L5, 1.3L5, 1.25L5, 1.2L5, 1.15L5, 1.1L5, 1.05L5, 1.08L5, 1.01L5.

[0103] Optional, see Figure 3 In the second direction Q, the size of the second isolation area 17 located on one side of the positioning area 13 is L7, L5=L7, and the setting of L7 is relatively appropriate, which can not only achieve a good isolation effect but also avoid space waste.

[0104] Optionally, in the first direction M, both sides of the positioning region 13 have collector doping regions with the same polarity, that is, in the first direction M, both sides of the positioning region 13 are first collector doping regions, or, in the first direction M, both sides of the positioning region 13 are second collector doping regions. The collector doping regions with the same polarity and both sides of the positioning region 13 have the first isolation region 14, and the collector doping regions with the same polarity and the positioning region 13 are effectively distinguished by the first isolation region 14, which is conducive to the alignment device to grasp the positioning region and achieve effective alignment.

[0105] Optionally, the first isolation region 14 here can be enclosed with the aforementioned second isolation region 17 to form a continuous isolation region, which is beneficial to the accuracy of grasping and positioning. Alternatively, the first isolation region 14 here can be enclosed with the aforementioned second isolation region 17 to form a continuous isolation region, or the first isolation region 14 can be separated from the aforementioned second isolation region 17, which can improve the patterning capacity and reduce the cost.

[0106] Optional, see Figure 4 The back contact battery cell also includes: a positioning electrode point 16, the orthographic projection of which on the battery body is located in the positioning area 13, in the second direction Q: the size of the positioning electrode point 16 is L8, the size of the positioning area 13 is L3, 0.4×L3<L8<0.8×L3, a positioning electrode point 16 that is too large will lead to risks such as leakage and slurry contamination, and a positioning electrode point 16 that is too small will lead to poor preparation positioning effect, 0.4×L3<L8<0.8×L3, the size of the positioning electrode point 16 is relatively appropriate, not only the risks of leakage and slurry contamination are small, but also the positioning effect is better.

[0107] For example, L8 can be 0.41L3, 0.45L3, 0.5L3, 0.55L3, 0.58L3, 0.6L3, 0.61L3, 0.65L3, 0.63L3, 0.7L3, 0.75L3, 0.79L3.

[0108] Optional, see Figure 5 The positioning areas 13 are axially symmetrically distributed in the back contact battery cell, and the axis of symmetry is parallel to the second direction Q. The lines connecting adjacent positioning areas 13 form a rectangular or square positioning area. When the positioning area is formed by laser, it is convenient for the camera to grasp and position, and is compatible with the electrode graphic design of the upper and lower halves, which can reduce the complexity of mass production.

[0109] Optional, see Figures 1 to 4 , the positioning region 13 is the first collector doping region or the second collector doping region. Figure 5 A back contact cell has at least two positioning areas that are collinear along a first direction M, and all the positioning areas that are collinear along the first direction M are first collector doping areas or second collector doping areas. The preparation process is simple, and the connecting lines of adjacent positioning areas 13 form a rectangular or square positioning area. When the positioning area is formed by laser, it is convenient for camera grasping and positioning, and is compatible with the electrode graphic design of the upper and lower halves, which can reduce the complexity of mass production.

[0110] Optionally, the number of the positioning areas 13 is 2 to 4, which is a more appropriate number, more accurate positioning, and less likely to form more dead zones. That is, the number of the positioning areas 13 can be 2, 3, or 4.

[0111] Optionally, the area of ​​a positioning area 13 is 0.5 mm 2 Up to 1.5mm 2 The area of ​​the positioning area 13 is more appropriate, the positioning is more accurate, and no more dead zones are formed. For example, the area of ​​a positioning area 13 can be 0.5mm 2 , 0.55mm 2, 0.6mm 2 、0.65mm 2 , 0.7mm 2 , 0.75mm 2 , 0.8mm 2 , 0.85mm 2 , 0.9mm 2 , 1.0mm 2 , 1.15mm 2 , 1.2mm 2 , 1.5mm 2 .

[0112] Optionally, the positioning region 13 is a P-type collector doping region, which is highly compatible with the existing processes of the back contact cell. It should be noted that in the back contact cell, the type of collector doping region is usually prepared first, and the positioning region 13 is the type of collector doping region. For example, in the back contact cell, an N-type collector doping region is prepared first, and the positioning region 13 is the N-type collector doping region. For another example, in the back contact cell, a P-type collector doping region is prepared first, and the positioning region 13 is the P-type collector doping region. The positioning region has the same layer structure, size, crystallization rate or roughness as the P-type collector doping region or the N-type collector doping region, that is, in the process of forming the positioning region, the collector doping region of the region will not be damaged. For example, the positioning region and the P-type collector doping region have the same layer structure, and along the direction away from the battery body, the corresponding position of the positioning region is provided with a tunnel passivation layer, a P-type doped polysilicon, a passivation anti-reflection layer and a metal electrode, wherein the size, crystallization rate and roughness and other parameters of the P-type doped polysilicon in the positioning region are the same as those of the P-type collector doping region; or along the direction away from the battery body, the corresponding position of the positioning region is provided with an intrinsic interface passivation layer, a P-type doped amorphous silicon, a TCO and a metal electrode, wherein the size, crystallization rate and roughness and other parameters of the P-type doped amorphous silicon in the positioning region are the same as those of the P-type collector doping region. The present application is not limited to this, and appropriate layer structure, size, crystallization rate or roughness and other parameters can be selected in the positioning region according to actual needs.

[0113] Optional, see Figure 1 , Figure 2 The back contact cell also includes: a first collector grid line 21 located on the first collector doping region, and a second collector grid line 22 located on the second collector doping region. The first collector grid line 21 and the second collector grid line 22 located on both sides of the positioning region 13 are spaced from the positioning region 13, which can reduce the risk of short circuit. Here, when the first collector doping region is an N-type collector doping region, the first collector grid line 21 is an N-type collector grid line, and here, when the first collector doping region is a P-type collector doping region, the first collector grid line 21 is a P-type collector grid line.

[0114] Optional, see Figure 1 , Figure 2 , the back contact cell also includes: a first collector grid line 21 located on the first collector doping region, and a second collector grid line 22 located on the second collector doping region. A first bus grid line located on the first bus doping region, and a second bus grid line located on the second bus doping region. At least part of the first collector grid line 21 intersects with the first bus grid line, and at least part of the second collector grid line 22 intersects with the second bus grid line, and current collection is conveniently realized through the collector grid line and the bus grid line. Here, when the first collector doping region is an N-type collector doping region, the first collector grid line 21 is an N-type collector grid line, the first bus doping region is an N-type bus doping region, and the first bus grid line is an N-type bus grid line. Here, when the first collector doping region is a P-type collector doping region, the first collector grid line 21 is a P-type collector grid line, the first bus doping region is a P-type bus doping region, and the first bus grid line is a P-type bus grid line.

[0115] Optional, see Figure 5 , the back contact cell also includes: a number of electrode disks located on the busbar line, which can exist as welding points in the process of forming a battery string. The electrode disks include: corresponding to the positioning area and at least two positioning electrode disks 23 away from the geometric center of the back contact cell, the shape of the positioning electrode disk 23 is different from the shape of the remaining electrode disks 24, at least two positioning electrode disks 23 are axially symmetrically distributed in the back contact cell, and the symmetry axis is parallel to the second direction Q, so that the connection line of the adjacent positioning electrode disks 23 can form a rectangular or square second positioning area. When the positioning area is formed by laser, it is convenient for the camera to grasp and position, and the electrode pattern design at different positions in the entire back contact cell can reduce the complexity of mass production. After the positioning electrode disk 23 is formed, it can exist as a positioning point for subsequent processes, which can further improve the positioning accuracy.

[0116] Optionally, the back contact cell also includes: insulating glue, which is at least located on the opposite collector grid line adjacent to the bus grid line to avoid short circuit. The positive projection of the insulating glue on the battery body is separated from the positioning area 13 to avoid the insulating glue covering the positioning area 13.

[0117] Optionally, in the first direction M, both sides of the positioning region 13 have collector doping regions with the same polarity, that is, in the first direction M, both sides of the positioning region 13 are first collector doping regions, or, in the first direction M, both sides of the positioning region 13 are second collector doping regions. A collector grid line extends from one side of the positioning region 13 through the positioning region 13 to the other side of the positioning region 13, and is continuously distributed on the collector doping regions with the same polarity in the first direction. The collector grid lines here can be continuously set. At this time, the first isolation region does not form a dead zone, and continuous collector grid lines can be used between adjacent collector grid lines for current collection, which has higher current collection efficiency. Optionally, a gap can be set between the collector grid lines with the same polarity on both sides of the above-mentioned positioning region 13 and the positioning region, which can save metal slurry and reduce costs, while reducing metal composites and improving the photoelectric conversion efficiency of the back contact cell.

[0118] The present application also provides another back-contact battery cell, comprising: a battery body; the battery body comprising: a plurality of battery cells and a partition area between adjacent battery cells, the battery cell comprising: a collector doping region, comprising a first collector doping region and a second collector doping region, the first collector doping region and the second collector doping region extending along a first direction and alternately spaced along a second direction; the first direction is different from the second direction; the first collector doping region and the second collector doping region have different doping types; a bus doping region, comprising a first bus doping region and a second bus doping region, the first bus doping region and the second bus doping region extending along the second direction and alternately spaced along the first direction; the first bus doping region and the second bus doping region have different doping types; the first bus doping region and the second bus doping region A collector doping region and the first bus doping region have the same polarity, and the second collector doping region and the second bus doping region have the same polarity; at least part of the first collector doping region intersects with the first bus doping region, and at least part of the second collector doping region intersects with the second bus doping region; in the first direction: a positioning region located between adjacent first bus doping regions and second bus doping regions, both sides of the positioning region have collector doping regions of at least one polarity, and the collector doping region of at least one polarity in the first direction has a first isolation region with at least one side of the positioning region, and in the second direction: both sides of the positioning region have collector doping regions of at least one polarity, and both sides of the collector doping region of at least one polarity in the second direction have a second isolation region with the positioning region. In the back contact cell, all positioning regions are symmetrical about the center of its cell body. The battery body, current collecting doping region, first current collecting doping region, second current collecting doping region, bus doping region, first bus doping region, second bus doping region, positioning region, first isolation region, first direction and second direction here can all correspond to the battery body, current collecting doping region, first current collecting doping region, second current collecting doping region, bus doping region, first bus doping region, second bus doping region, positioning region, first isolation region, first direction and second direction in the aforementioned back contact battery cell. In order to avoid repetition, they will not be repeated here.

[0119] Optionally, the positioning area 13 passes through the center line between the adjacent first and second convergence doping areas, and the center line between the adjacent first and second convergence doping areas is parallel to the second direction, so that the connection line of the four adjacent positioning areas 13 in the back contact cell forms a rectangular or square positioning area. When the positioning area is formed by laser, the stringent requirements for the distance from the alignment light source can be reduced, and more graphical light sources can be compatible, while achieving uniform collection of PN region carriers. Moreover, in the back contact cell, the position of the positioning area 13 is conducive to forming a centrally symmetrical back contact cell, which reduces the difficulty of interconnection alignment during the electrical connection of the back contact cell obtained after slicing, and the operation is simple.

[0120] Optionally, the back contact cell is sliced ​​along the segmentation area to obtain any of the aforementioned back contact cells, and after slicing, one of the aforementioned battery cells corresponds to any of the aforementioned back contact cells. The segmentation area here can extend along the aforementioned first direction M, that is, the back contact cell is a whole cell before slicing. A back contact cell includes several battery cells, and after slicing, several back contact cells are usually obtained, and the number of back contact cells obtained after slicing is not specifically limited.

[0121] The back-contact cell has the same or similar beneficial effects as any of the aforementioned back-contact cells, and will not be described again here to avoid repetition.

[0122] The present application also provides a method for preparing a back-contact solar cell, comprising the following steps.

[0123] Step 101, providing a silicon substrate; the silicon substrate comprises a first surface and a second surface opposite to each other.

[0124] The crystal type and doping type of the silicon substrate are not specifically limited. During normal operation of the back contact cell, the surface of the silicon substrate that mainly receives light is the light-facing surface, that is, the second surface here, and the backlight surface of the silicon substrate, that is, the first surface, is opposite to the light-facing surface.

[0125] Step 102: forming a first doping layer on a first surface of the silicon substrate.

[0126] That is, a first doping layer is formed on the first surface of the silicon substrate in its entirety, and the formation method is not limited.

[0127] Step 103, removing a portion of the first doping layer, so that the first surface is partially exposed, and the remaining first doping layer forms a plurality of first collector doping regions extending along the first direction and spaced along the second direction, and a plurality of first bus doping regions extending along the second direction and spaced along the first direction; at least a portion of the first collector doping regions intersects with the first bus doping regions; a portion of the plurality of first collector doping regions covers the positioning region, and the first doping layer around the positioning region is removed. The first direction is different from the second direction.

[0128] Reference Figure 6 , Figure 6 The shaded portion in the figure is the exposed first surface of the silicon substrate 1. Figure 6 The shaded portion is the portion where the first doping layer is removed, and the white portion is the remaining first doping layer. The remaining first doping layer includes: a plurality of first collector doping regions extending along the first direction M and spaced along the second direction Q, and a plurality of first bus doping regions extending along the second direction Q and spaced along the first direction M. At least part of the first collector doping region intersects with the first bus doping region. After removing part of the first doping layer, the exposed first surface is where the second collector doping region and the second bus doping region are to be formed later. For example, Figure 6 In the figure, the shaded portion framed by the dotted line on the left is the location where the second collector doping region and the second bus doping region are to be formed subsequently, as well as the subsequent isolation region, where the isolation region includes the first isolation region, the second isolation region and the third isolation region.

[0129] Optionally, a first laser method can be used to remove a partial area of ​​the first doped layer. The laser in the first laser method loosens a partial area of ​​the first doped layer, and then cleans it to clean the loosened part of the first doped layer. The laser method can be used to easily remove a partial area of ​​the first doped layer.

[0130] Part of the first collector doping regions covers the positioning region 13, and the first doping layer around the positioning region 13 is removed. Figure 6 The square blank area R in the middle is where the positioning area 13 is to be formed later. The first doped layer can be an N-type doped layer or a P-type doped layer, and there is no specific limitation on this. If the first doped layer is an N-type doped layer, the first collector doped region is an N-type collector doped region, and the first bus doped region is an N-type bus doped region. If the first doped layer is a P-type doped layer, the first collector doped region is a P-type collector doped region, and the first bus doped region is a P-type bus doped region.

[0131] Step 104 , forming a second doping layer on the exposed first surface and the remaining first doping layer; the first doping layer and the second doping layer have different doping types.

[0132] This step is to form a whole second doped layer on the back side of the silicon substrate based on step 103. If the first doped layer is an N-type doped layer, the second doped layer is a P-type doped layer. If the first doped layer is a P-type doped layer, the second doped layer is an N-type doped layer.

[0133] Step 105, removing part of the area of ​​the second doping layer so that the several first collector doping areas and the several first bus doping areas are exposed, forming first collector doping areas and second collector doping areas extending along the first direction and alternately spaced along the second direction, first bus doping areas and second bus doping areas extending along the second direction and alternately spaced along the first direction, and the positioning area, at least part of the second collector doping area and the second bus doping area intersect; in the first direction: a positioning area located between adjacent first bus doping areas and second bus doping areas, and the two sides of the positioning area have the collector doping areas of at least one polarity, and the collector doping area of ​​at least one polarity in the first direction has a first isolation area from at least one side of the positioning area; in the second direction: the two sides of the positioning area have the collector doping areas of at least one polarity, and the collector doping area of ​​at least one polarity in the second direction has a second isolation area from both sides of the positioning area.

[0134] The first collector doping region is one of an N-type collector doping region and a P-type collector doping region, and the second collector doping region is the other of the N-type collector doping region and the P-type collector doping region. The first bus doping region is one of an N-type bus doping region and a P-type bus doping region, and the second bus doping region is the other of the N-type bus doping region and the P-type bus doping region. The first collector doping region and the first bus doping region have the same polarity or the same doping type, and the second collector doping region and the second bus doping region have the same polarity or the same doping type.

[0135] Reference Figure 7, step 105 is to remove part of the second doping layer, expose the several first collector doping regions and several first bus doping regions formed above, and remove the second doping layer in the isolation region to form an isolation region, the isolation region includes: a first isolation region, a second isolation region and a third isolation region, and form a first collector doping region and a second collector doping region extending in the first direction and alternately spaced along the second direction, a first bus doping region and a second bus doping region extending in the second direction and alternately spaced along the first direction, and the positioning region. At least part of the first collector doping region intersects with the first bus doping region, and at least part of the second collector doping region intersects with the second bus doping region. It should be noted that, Figure 6 , Figure 7 The boxes are only used to illustrate different areas and do not actually exist in the back contact cell.

[0136] Optionally, the partial area where the first doping layer is removed and the partial area where the second doping layer is removed partially overlap, so that at least a portion of the area around the positioning area is exposed to the silicon substrate, and the exposed silicon substrate forms the first isolation area and the second isolation area. The formation method of the first isolation area and the second isolation area can be compatible with related processes in existing processes. The process method is simple and can form a positioning area that is easy to grasp.

[0137] Optionally, the laser in the second laser method can be used to loosen a portion of the second doped layer, and then clean it to clean the loosened portion of the second doped layer, thereby removing a portion of the second doped layer. The laser method here can be compatible with the two laser methods in the existing process to form the aforementioned positioning area, and the process method is simple.

[0138] Optionally, the area where the first doped layer is partially removed includes a first laser area similar to a picture frame, and the area where the second doped layer is partially removed includes a square second laser area, wherein the second laser area covers the inner frame of the first laser area and extends to cover a portion of the picture frame, thereby forming a first isolation area and a second isolation area. The above method is compatible with the existing process flow of back contact solar cells, and does not require special process treatment for the positioning area, while ensuring that the height of the positioning area is not too high to avoid affecting the printing quality of the gate line.

[0139] Optionally, the method may further include: preparing multiple gate lines, wherein the positioning area 13 may be used as a positioning point to prepare the first gate line and form a positioning electrode point 16 in the positioning area 13. Then, the positioning electrode point 16 is used as a positioning point to prepare the remaining gate lines, thereby forming a precise alignment between the back contact cell gate line and the corresponding doping area, and more effectively collecting the current.

[0140] It should be noted that the method for preparing the back-contact battery cell is used to prepare any of the aforementioned back-contact battery cells, and the related parts of the two can be referenced to each other. In order to avoid repetition, they will not be described again here.

[0141] The present application also provides a photovoltaic module, which includes: a number of any of the aforementioned back-contact cell sheets, and other structures of the photovoltaic module are not specifically limited. For example, the photovoltaic module may also include a packaging film located on opposite sides of the back-contact cell sheet, etc., which is not specifically limited.

[0142] The present application also provides a photovoltaic assembly, the photovoltaic assembly comprising:

[0143] A plurality of back-contact battery cells; the back-contact battery cells include: a battery body, the battery body includes: a collector doping region, including a first collector doping region and a second collector doping region, the first collector doping region and the second collector doping region extend along a first direction and are alternately spaced along a second direction; the first direction is different from the second direction; the first collector doping region and the second collector doping region have different doping types, one of which is an N-type collector doping region and the other is a P-type collector doping region.

[0144] The back contact cell further comprises: a collector grid line located on the cell body, the collector grid line comprising a first collector grid line located on the first collector doping region, and a second collector grid line located on the second collector doping region;

[0145] An interconnection member; the interconnection member electrically connects two adjacent back-contact battery cells, one end of the interconnection member is electrically connected to the second collector grid line of one of the two adjacent back-contact battery cells, and the other end of the interconnection member is electrically connected to the first collector grid line of the other of the two adjacent back-contact battery cells;

[0146] The battery body also includes:

[0147] In the first direction: a positioning region between adjacent interconnects, and both sides of the positioning region have collector doping regions of at least one polarity, and the collector doping region of at least one polarity in the first direction and at least one side of the positioning region have a first isolation region;

[0148] In the second direction: both sides of the positioning region have collector doping regions of at least one polarity, and both sides of the collector doping region of at least one polarity and the positioning region in the second direction have second isolation regions.

[0149] Optionally, the back-contact cell included in the above-mentioned photovoltaic module is basically the same as the cell in other embodiments of the present application. The difference is that the back-contact cell in the present embodiment may not have a bus doping region and may not have a bus grid line. The bus grid line is replaced by an interconnection component, and electrical connection is made through the interconnection component and the collector grid line, which saves metal slurry, reduces the recombination caused by the metal slurry, and improves the output power of the photovoltaic module.

[0150] Optionally, the interconnection component may be a solder strip or a conductive backplane having the function of an interconnection component. The conductive backplane can simplify the arrangement process of battery interconnection and reduce the difficulty of rework.

[0151] The photovoltaic module has the same or similar beneficial effects as any of the aforementioned back-contact solar cells, and the relevant parts can be referenced to each other, which will not be described again here to avoid repetition.

[0152] The present application is further explained below with reference to specific embodiments.

[0153] Example 1

[0154] In the first step, an N-type silicon substrate is provided; the N-type silicon substrate comprises a first surface and a second surface opposite to each other.

[0155] In the second step, borosilicate glass (BSG) is formed on the first surface of the N-type silicon substrate to form a P-type doping layer.

[0156] In the third step, a partial area of ​​the P-type doped layer is removed by the first laser method, so that the first surface of the N-type silicon substrate is partially exposed, and the remaining P-type doped layer includes: a plurality of P-type collector doped regions extending along the first direction M and spaced along the second direction Q, and a plurality of P-type bus doped regions extending along the second direction Q and spaced along the first direction M. Part of the plurality of P-type collector doped regions covers the positioning region, and the P-type doped layers around the positioning region are all removed.

[0157] In the fourth step, an N-type doped layer is formed on the exposed first surface and the remaining P-type doped layer.

[0158] In the fifth step, a second laser method is used to remove part of the N-type doped layer, so that several P-type collector doped regions and several P-type bus doped regions formed in the third step are exposed, forming P-type collector doped regions and N-type collector doped regions extending in the first direction and distributed alternately in the second direction, P-type bus doped regions and N-type bus doped regions extending in the second direction and distributed alternately in the first direction, and the positioning region, at least part of the P-type collector doped regions and the P-type bus doped regions intersect, and at least part of the N-type collector doped regions and the N-type bus doped regions intersect. The N-type doped layer around the positioning region is removed to form an isolation region. In the first direction, the positioning region is located between adjacent N-type bus doped regions and P-type bus doped regions. Refer to Figure 1 , in the first direction, both sides of the positioning region have collector doping regions with opposite polarities. A first isolation region 14 is provided between the collector doping regions with opposite polarities and the positioning region in the first direction. In the second direction: both sides of the positioning region 13 have N-type collector doping regions 11 with the same polarity, and both sides of the N-type collector doping regions 11 with the same polarity and the positioning region 13 in the second direction have second isolation regions, and the first isolation region and the second isolation region are enclosed to form a continuous isolation region.

[0159] In the fifth step, four positioning areas are formed. The coordinate origin is the position corresponding to the geometric center of the silicon substrate. The coordinate positions of the geometric centers of the four positioning areas are (-61.63 63.78), (61.63 63.78), (-61.63-63.78), and (61.63 63.78). The area of ​​a positioning area here is 1mm 2 .

[0160] In the sixth step, in the process of forming the back contact cell, the gate line is formed by three printings in total. The first gate line printing is performed first and the positioning electrode point 16 is printed in the positioning area. The subsequent printings are all based on the positioning electrode point 16 as the positioning point. In the subsequent printing process of the insulating glue, the positioning electrode point 16 can also be used as the positioning point. The positioning area 13 and the positioning electrode point 16 of the present application can improve the positioning accuracy.

[0161] The back-contact cell sheet is sliced ​​along a direction parallel to the first direction to obtain two halves of the back-contact cell sheet.

[0162] Example 2

[0163] The main difference between Example 2 and Example 1 is that the area of ​​a positioning area in Example 2 is 0.8 mm 2 , the rest can refer to the aforementioned embodiment 1.

[0164] Example 3

[0165] The main difference between Example 3 and Example 1 is that in Example 3, in the first direction, only one of the two sides of the positioning region has a collector doping region, and the rest can refer to the aforementioned Example 1.

[0166] Comparative Example 1

[0167] The main difference between Comparative Example 1 and Example 1 is that the area of ​​a positioning area in Comparative Example 1 is 0.3 mm 2 , the rest can refer to the aforementioned embodiment 1.

[0168] Comparative Example 2

[0169] Comparative Example 2 uses the edge grasping positioning in the related art for positioning.

[0170] Comparative Example 3

[0171] Comparative Example 3 uses the cross positioning or prototype positioning in the related art to perform single positioning.

[0172] Comparative Example 4

[0173] The main difference between Comparative Example 4 and Example 1 is that in Comparative Example 4, in the first direction, there are no collector doping regions on both sides of the positioning region, and the rest can refer to the aforementioned Example 1.

[0174] The sizes of the back contact cells obtained in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 are all equal. 100,000 back contact cells are obtained in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4. The performance of the back contact cells obtained in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 is tested under the same test conditions.

[0175] Figure 8 In the example, the edge-grabbing positioning corresponds to comparative example 2, the one-time positioning corresponds to comparative example 3, and the two-time positioning corresponds to embodiment 1. Under the same test conditions, the average value of the back contact cell positioning accuracy of comparative example 2, comparative example 3 and embodiment 1 is obtained by testing. Figure 8 It can be concluded that the alignment accuracy of the 100,000 back-contact solar cells obtained in Example 1 provided in the present application reaches 100%, which is significantly higher than the alignment accuracy of Comparative Examples 2 and 3.

[0176] Fig. 9 The vertical axis is the short-circuit current, in mA (milliamperes). Fig. 9In the example, connection 1 corresponds to comparative example 4, connection 2 corresponds to embodiment 3, and connection 3 corresponds to embodiment 1. Under the same test conditions, the average short-circuit current of the back contact battery cells of comparative example 4, embodiment 3 and embodiment 1 is obtained by testing. Fig. 9 It can be concluded that the average short-circuit current of the back-contact cell of Example 1 provided in this application reaches 14.811 mA, indicating that by setting collector doping regions with opposite polarities on both sides of the positioning region in the first direction, the current can be effectively increased, and the current collection problem caused by the large dead zone of the positioning region can be avoided. Fig. 9 It can be concluded that the average short-circuit current of the back-contact cell of Example 3 provided in the present application reaches 14.808 mA, indicating that by setting a current collecting doping region only on one side of the two sides of the positioning area in the first direction, the current can be effectively increased, and the current collection problem caused by the large dead zone of the positioning area can be avoided.

[0177] Fig.10 The vertical axis is the short-circuit current in mA. Fig.10 In the figure, area 1 corresponds to one back-contact cell in Example 1, area 2 corresponds to one back-contact cell in Example 2, and area 3 corresponds to one back-contact cell in Comparative Example 1. Under the same test conditions, the short-circuit currents of the back-contact cells in Example 1, Example 2, and Comparative Example 1 were measured. Fig.10 It can be concluded that the short-circuit current of the back-contact cell of Example 1 provided in the present application reached 14.803 mA, and the short-circuit current of the back-contact cell of Example 2 reached 14.812 mA, which were significantly higher than those of Comparative Example 1. This indicates that in the present application, the area of ​​a positioning region is appropriately set, which is not only accurate in positioning and conducive to the effective collection of current, but also results in a smaller dead zone.

[0178] In summary, this application mainly adopts the design concept of double positioning, and designs the positioning area between the adjacent first bus doping area and the second bus doping area, which can effectively solve the interference of the bus grid line on the positioning effect. At the same time, in the first direction, both sides of the positioning area have collector doping areas of at least one polarity, which can solve the problem of poor carrier collection caused by the dead zone. In addition, the area size of the positioning area, the relevant dimensions of the positioning area, and the number of positioning areas are standardized, so as to achieve a good positioning effect and a good current collection effect, and the risk of short circuit is relatively small.

[0179] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0180] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A back contact battery cell, characterized in that: include: The battery body comprises: The collector doping region comprises a first collector doping region and a second collector doping region, wherein the first collector doping region and the second collector doping region extend along a first direction and are alternately spaced along a second direction; the first direction is different from the second direction; and the first collector doping region and the second collector doping region have different doping types; A bus doping region, comprising a first bus doping region and a second bus doping region, wherein the first bus doping region and the second bus doping region extend along the second direction and are alternately spaced and distributed along the first direction; the first bus doping region and the second bus doping region have different doping types; the first collector doping region and the first bus doping region have the same polarity, and the second collector doping region and the second bus doping region have the same polarity; at least a portion of the first collector doping region intersects with the first bus doping region, and at least a portion of the second collector doping region intersects with the second bus doping region; In the first direction: a positioning region located between adjacent first bus doping regions and second bus doping regions, and both sides of the positioning region have the collector doping regions of at least one polarity, and the collector doping region of at least one polarity in the first direction has a first isolation region from at least one side of the positioning region; In the second direction: both sides of the positioning region have collector doping regions of at least one polarity, and both sides of the collector doping region of at least one polarity and the positioning region in the second direction have second isolation regions.

2. The back contact cell according to claim 1, characterized in that: The bus doping region is only disposed at at least one end portion of the battery body along the second direction, and in the second direction, there is a gap between the bus doping region and the positioning region.

3. The back contact cell according to claim 1, characterized in that: In the first direction: both sides of the positioning region have collector doping regions with opposite polarities, and both sides of the collector doping regions with opposite polarities and the positioning region in the first direction have first isolation regions, and the first isolation region and the second isolation region are enclosed into a continuous isolation region.

4. The back contact cell according to claim 3, characterized in that: Also includes: In the collector doping regions with opposite polarities in the first direction, the first collector gate line located on the first collector doping region and the second collector gate line located on the second collector doping region, the first collector gate line and the second collector gate line located on both sides of the positioning region are spaced apart from the positioning region.

5. The back contact cell according to claim 3, characterized in that: In the first direction: the size of the positioning area is L1, the distance between the collector doping areas with opposite polarities in the first direction is L2; ​​L2>L1>L2 / 2; and / or, In the second direction, the size of the positioning area is L3, and the distance between two adjacent collector doping regions with the same polarity is L4; L4>L3>L4 / 2.

6. The back contact cell according to claim 1, characterized in that: A third isolation region is provided between the adjacent first collector doping region and the second collector doping region; In the second direction, the size of the third isolation region is L5; In the first direction, a size of the first isolation area located on one side of the positioning area is L6; In the second direction, a size of the second isolation area located on one side of the positioning area is L7; 1.5×L5>L6>L5; and / or, L5=L7.

7. The back contact cell according to claim 1, characterized in that: Also includes: A positioning electrode point, wherein the orthographic projection of the positioning electrode point on the battery body is located in the positioning area; In the second direction: the size of the positioning electrode point is L8, and the size of the positioning area is L3; 0.4×L3<L8<0.8×L3.

8. The back contact cell according to claim 1, characterized in that: In the first direction, both sides of the positioning area have the collector doping region with the same polarity; in the first direction, both sides of the collector doping region with the same polarity and the positioning area have the first isolation region, and the first isolation region and the second isolation region are enclosed into a continuous isolation area.

9. The back contact cell according to claim 8, characterized in that: Also includes: In the collector doping region with the same polarity in the first direction, the first collector gate line located on the first collector doping region, and the second collector gate line located on the second collector doping region, at least one of the first collector gate line or the second collector gate line extends from one side of the positioning region through the positioning region to the other side of the positioning region, and is continuously distributed on the collector doping region with the same polarity in the first direction.

10. The back contact cell according to claim 1, characterized in that: In the second direction: both sides of the positioning region have the collector doping regions with the same polarity, and both sides of the collector doping regions with the same polarity and the positioning region in the second direction have the second isolation region.

11. The back contact cell according to claim 1, characterized in that: The positioning areas are axially symmetrically distributed in the back contact cell sheet, and the axis of symmetry is parallel to the second direction.

12. The back contact cell according to claim 1, characterized in that: The positioning region is one of a first collector doping region and a second collector doping region; The back contact cell has at least two positioning regions collinearly along the first direction; all the positioning regions collinearly along the first direction are first collector doping regions or second collector doping regions.

13. The back contact cell according to claim 1, characterized in that: The number of the positioning areas is 2 to 4; or, The area of ​​one of the positioning areas is 0.5 mm 2 Up to 1.5mm 2 .

14. The back contact solar cell according to any one of claims 1 to 13, characterized in that: The positioning region is a P-type collector doping region.

15. The back contact cell according to claim 4 or 9, characterized in that: Also includes: A first bus gate line located on the first bus doping region, and a second bus gate line located on the second bus doping region; at least part of the first collector gate line intersects with the first bus gate line, and at least part of the second collector gate line intersects with the second bus gate line.

16. The back contact cell according to claim 15, characterized in that: Also includes: A plurality of electrode plates located on the busbar line; the plurality of electrode plates include: at least two positioning electrode plates corresponding to the positioning area and away from the geometric center of the back contact battery sheet; The shape of the positioning electrode disk is different from the shapes of the remaining electrode disks; At least two of the positioning electrode plates are axially symmetrically distributed in the back contact battery sheet, and the axis of symmetry is parallel to the second direction.

17. The back contact cell according to claim 15, characterized in that: Also includes: Insulation glue; The insulating glue is at least located on the opposite-sex collector grid line that is adjacent to the bus grid line; The orthographic projection of the insulating glue on the battery body is separated from the positioning area.

18. A back contact battery cell, characterized in that: include: Battery body; The battery body comprises: a plurality of battery cells and a partition area between adjacent battery cells, wherein the battery cells comprise: The collector doping region comprises a first collector doping region and a second collector doping region, wherein the first collector doping region and the second collector doping region extend along a first direction and are alternately spaced along a second direction; the first direction is different from the second direction; and the first collector doping region and the second collector doping region have different doping types; A bus doping region, comprising a first bus doping region and a second bus doping region, wherein the first bus doping region and the second bus doping region extend along the second direction and are alternately spaced and distributed along the first direction; the first bus doping region and the second bus doping region have different doping types; the first collector doping region and the first bus doping region have the same polarity, and the second collector doping region and the second bus doping region have the same polarity; at least a portion of the first collector doping region intersects with the first bus doping region, and at least a portion of the second collector doping region intersects with the second bus doping region; In the first direction: a positioning region located between adjacent first bus doping regions and second bus doping regions, and both sides of the positioning region have the collector doping regions of at least one polarity, and the collector doping region of at least one polarity in the first direction has a first isolation region from at least one side of the positioning region; In the second direction: both sides of the positioning region have collector doping regions of at least one polarity, and both sides of the collector doping region of at least one polarity and the positioning region in the second direction have second isolation regions; All the positioning areas are symmetrical about the center of the battery body.

19. The back contact cell according to claim 18, characterized in that: The positioning region passes through a center line between the adjacent first bus doping region and the second bus doping region.

20. The back contact cell according to claim 18 or 19, characterized in that: The back-contact cell sheet is sliced ​​along the dividing area to obtain the back-contact cell sheet as claimed in any one of claims 1 to 17.

21. A method for preparing a back contact battery cell, characterized in that: include: providing a silicon substrate; The silicon substrate comprises a first surface and a second surface opposite to each other; forming a first doping layer on a first surface of the silicon substrate; Part of the first doping layer is removed so that the first surface is partially exposed, and the remaining first doping layer includes: a plurality of first collector doping regions extending along the first direction and spaced apart along the second direction, and a plurality of first bus doping regions extending along the second direction and spaced apart along the first direction; at least a portion of the first collector doping regions intersects with the first bus doping regions; a portion of the plurality of first collector doping regions covers a positioning region, and the first doping layer around the positioning region is removed; wherein the first direction is different from the second direction; forming a second doping layer on the exposed first surface and the remaining first doping layer; the first doping layer and the second doping layer have different doping types; Removing a portion of the second doping layer so that the plurality of first collector doping regions and the plurality of first bus doping regions are exposed, forming first collector doping regions and second collector doping regions extending along the first direction and alternately spaced along the second direction, first bus doping regions and second bus doping regions extending along the second direction and alternately spaced along the first direction, and the positioning region, at least a portion of the second collector doping region and the second bus doping region intersect; In the first direction: a positioning region located between adjacent first bus doping regions and second bus doping regions, and both sides of the positioning region have the collector doping regions of at least one polarity, and the collector doping region of at least one polarity in the first direction has a first isolation region from at least one side of the positioning region; In the second direction: both sides of the positioning region have collector doping regions of at least one polarity, and both sides of the collector doping region of at least one polarity and the positioning region in the second direction have second isolation regions.

22. The method for preparing a back contact solar cell according to claim 21, characterized in that: The method further comprises: multiple gate line preparations, wherein the first gate line preparation is performed using the positioning area as a positioning point and a positioning electrode point is formed in the positioning area; The positioning electrode points are used as positioning points to prepare the remaining grid lines.

23. The method for preparing a back contact solar cell according to claim 21 or 22, characterized in that: The partial area where the first doping layer is removed partially overlaps with the partial area where the second doping layer is removed, so that at least a partial area around the positioning area is exposed to the silicon substrate, and the exposed silicon substrate forms the first isolation area and the second isolation area.

24. A photovoltaic module, characterized in that: include: A back contact solar cell as claimed in any one of claims 1 to 17.

25. A photovoltaic module, characterized in that: include: Multiple back contact cells; The back contact cell comprises: a cell body, the cell body comprises: a collector doping region, comprising a first collector doping region and a second collector doping region, the first collector doping region and the second collector doping region extending along a first direction and alternately spaced along a second direction; the first direction is different from the second direction; the first collector doping region and the second collector doping region have different doping types; The back contact cell further comprises: a collector grid line located on the cell body, the collector grid line comprising a first collector grid line located on the first collector doping region, and a second collector grid line located on the second collector doping region; An interconnection member; the interconnection member electrically connects two adjacent back-contact battery sheets, one end of the interconnection member is electrically connected to the second collector grid line of one of the two adjacent back-contact battery sheets, and the other end of the interconnection member is electrically connected to the first collector grid line of the other of the two adjacent back-contact battery sheets; The battery body also includes: In the first direction: a positioning region located between adjacent interconnects, and both sides of the positioning region have the collector doping region of at least one polarity, and the collector doping region of at least one polarity in the first direction has a first isolation region with at least one side of the positioning region; In the second direction: both sides of the positioning region have collector doping regions of at least one polarity, and both sides of the collector doping region of at least one polarity and the positioning region in the second direction have second isolation regions.

Images