Back contact solar cell, slice, assembly and photovoltaic system

Abstract

The invention discloses a back contact solar cell, an assembly and a photovoltaic system, and relates to the field of silicon solar cells. The back contact solar cell comprises a silicon substrate, a first doping layer, a second doping layer, a positive electrode grid line, a negative electrode grid line and a first PAD part. The first doping layers and the second doping layers are alternately arranged along a first direction; the first doped layer comprises a first sub-doped layer, and the second doped layer comprises a second sub-doped layer adjacent to the first sub-doped layer; the second doping sub-layer and the first doping sub-layer form an electric leakage composite contact structure at a preset position; the positive grid line comprises a first sub-positive grid line arranged on the first sub-doping layer, and the negative grid line comprises a first sub-negative grid line arranged on the second sub-doping layer; each group of first PAD parts comprises a first PAD point and a second PAD point, the first PAD point is electrically connected with the first sub positive grid line, and the second PAD point is electrically connected with the first sub negative grid line. By implementing the method, the hot spot effect can be accurately represented at the battery end.

Description

Technical Field

[0001] The present invention relates to the field of silicon solar cells, and in particular to a back-contact solar cell, a slice, a component and a photovoltaic system. Background Art

[0002] When one or more solar cells (or slices) in a photovoltaic module are partially or completely shielded, the shielded solar cells (slices) will show a voltage reverse bias characteristic and become a load, consuming the power generated by normal solar cells, thereby generating a large amount of heat, making the temperature of the solar cell higher, which is generally referred to as the hot spot effect. In the prior art, in order to solve the hot spot problem, a diode is generally connected in reverse parallel at both ends of the string unit to reduce the current of the shielded solar cell and weaken the hot spot effect. However, this parallel diode will produce power loss. In order to solve this problem, a feasible idea is to directly form a leakage composite contact structure on the solar cell (see CN117976743B), that is, in the process of making solar cells, the doping layers of different polarities are partially contacted, thereby effectively reducing the reverse voltage at both ends of the shielded solar cell, reducing heat generation, and weakening the hot spot effect. After adopting this method, the control of the hot spot effect can be moved forward to the end of the solar cell. Therefore, how to evaluate the hot spot effect at the end of the solar cell has become a technical problem that needs to be solved by those skilled in the art.

[0003] Conventional hot spot effect testing generally involves shielding any one or more solar cells (or sub-cells) in a solar cell module, while exposing the other solar cells (or sub-cells) to light. After a certain period of time, the temperature of the shielded solar cell sub-cell is tested to characterize the hot spot effect. This is obviously not suitable for testing the hot spot effect at the solar cell end.

[0004] In addition, conventional testing equipment for solar cells, such as conventional IV test probes and PCB boards, cannot perform reverse voltage characteristic tests due to difficulty in aligning fine grids, making it difficult to further characterize the anti-hot spot characteristics of the cell. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a back-contact solar cell, a cell string, a component and a photovoltaic system, which can realize quantitative evaluation of hot spot effect at the cell end.

[0006] In order to solve the above problems, the present invention discloses a back contact solar cell, which comprises:

[0007] A silicon substrate, comprising a light-receiving surface and a backlight surface that are arranged opposite to each other;

[0008] A plurality of first doping layers and a plurality of second doping layers are arranged on the backlight surface, the plurality of first doping layers and the plurality of second doping layers are alternately arranged along a first direction and extend along a second direction; the first doping layer includes at least one first sub-doping layer, the second doping layer includes a second sub-doping layer arranged adjacent to the first sub-doping layer; the second sub-doping layer and the first sub-doping layer form a leakage composite contact structure at a preset position;

[0009] A plurality of positive gate lines and a plurality of negative gate lines, wherein the positive gate lines are arranged on the first doped layer, and the negative gate lines are arranged on the second doped layer; the positive gate lines include a first sub-positive gate line arranged on the first sub-doped layer, and the negative gate lines include a first sub-negative gate line arranged on the second sub-doped layer;

[0010] At least one group of first PAD parts, each group of the first PAD parts includes a first PAD point and a second PAD point, the first PAD point is electrically connected to the first sub-positive gate line, and the second PAD point is electrically connected to the first sub-negative gate line.

[0011] As an improvement of the above technical solution, the silicon substrate has a first edge and a second edge arranged opposite to each other in a first direction; along the direction from the first edge to the second edge, the backlight surface includes a first edge area, a middle area and a second edge area;

[0012] The first PAD portion is disposed in the first edge region and the second edge region; or

[0013] The first PAD portion is disposed in the middle area; or

[0014] The first PAD portion is disposed in the first edge region, the middle region, and the second edge region.

[0015] As an improvement of the above technical solution, the first PAD portion is only provided in the first edge region and the second edge region.

[0016] As an improvement of the above technical solution, a second PAD portion is further provided in the first edge region and / or the second edge region;

[0017] The second PAD portion includes a third PAD point and a fourth PAD point, the third PAD point is electrically connected to the positive gate line, and the fourth PAD point is electrically connected to the negative gate line.

[0018] As an improvement of the above technical solution, the silicon substrate has a third edge and a fourth edge that are arranged opposite to each other in the second direction;

[0019] A first PAD point of a first PAD portion disposed in the first edge region and the second edge region is disposed close to the third edge, and a second PAD point of a first PAD portion disposed in the first edge region and the second edge region is disposed close to the fourth edge;

[0020] No third PAD point or fourth PAD point is set between the first PAD point and the third edge;

[0021] No third PAD point or fourth PAD point is arranged between the second PAD point and the fourth edge.

[0022] As an improvement of the above technical solution, a first PAD point of the first PAD part in the middle area is arranged close to the third edge, and a second PAD point of the first PAD part in the middle area is arranged close to the fourth edge.

[0023] As an improvement of the above technical solution, the first doping layer includes 5 to 20 first sub-doping layers, each of which is provided with a first sub-positive electrode grid line, and each of the first sub-positive electrode grid lines is connected to a first PAD point;

[0024] The second doping layer includes 5 to 20 second sub-doping layers, each of which is provided with a first sub-negative electrode grid line, and each of the first sub-negative electrode grid lines is connected to a second PAD point.

[0025] As an improvement of the above technical solution, the first doping layer includes 5 to 20 first sub-doping layers, and the plurality of first sub-doping layers are distributed along the first direction; each of the first sub-doping layers is provided with a first sub-positive electrode grid line, and a first PAD point is provided every other first sub-positive electrode grid line;

[0026] The second doping layer includes 5 to 40 second sub-doping layers, and the plurality of second sub-doping layers are distributed along the first direction. Each of the second sub-doping layers is provided with a first sub-negative gate line, and a second PAD point is provided every other first sub-negative gate line.

[0027] As an improvement of the above technical solution, the width of the first positive sub-gridline is greater than the width of other positive gridlines.

[0028] As an improvement of the above technical solution, it includes 1 to 12 groups of first PAD parts.

[0029] As an improvement of the above technical solution, it also includes:

[0030] a first shunt gate line and a second shunt gate line, wherein the first shunt gate line is electrically connected to a plurality of the positive gate lines, and the second shunt gate line is electrically connected to a plurality of the negative gate lines;

[0031] The first shunt gate line is electrically connected to the first PAD point, and the second shunt gate line is electrically connected to the second PAD point.

[0032] As an improvement of the above technical solution, it also includes:

[0033] a first shunt gate line and a second shunt gate line, wherein the first shunt gate line electrically connects all positive gate lines located on the backlight surface, and the second shunt gate line electrically connects all negative gate lines located on the backlight surface;

[0034] The first shunt gate line is electrically connected to the first PAD point, and the second shunt gate line is electrically connected to the second PAD point.

[0035] As an improvement of the above technical solution, the silicon substrate has a third edge and a fourth edge that are arranged opposite to each other in the second direction;

[0036] The first shunt gate line is disposed close to the third edge, and the second shunt gate line is disposed close to the fourth edge.

[0037] As an improvement of the above technical solution, the positive gate line and the negative gate line are arranged on a side of the first shunt gate line facing the fourth edge;

[0038] The positive gate line and the negative gate line are arranged on a side of the second shunt gate line facing the third edge.

[0039] As an improvement of the above technical solution, the distance between the first PAD point and the third edge is greater than the distance between the first shunt gate line and the third edge;

[0040] The distance between the second PAD point and the fourth edge is greater than the distance between the second shunt gate line and the fourth edge.

[0041] As an improvement of the above technical solution, the distance between the first PAD point and the third edge is 3 mm to 5 mm; the distance between the second PAD point and the fourth edge is 3 mm to 5 mm;

[0042] The distance between the first shunt gate line and the third edge is 0.2 mm to 2 mm, and the distance between the second shunt gate line and the fourth edge is 0.2 mm to 2 mm.

[0043] As an improvement of the above technical solution, the first PAD point is electrically connected to the first shunt gate line through a first connecting gate line;

[0044] The second PAD point is electrically connected to the second shunt gate line through a second connecting gate line.

[0045] As an improvement of the above technical solution, the first connecting grid line is located on the extension line of the first sub-positive grid line to the third edge;

[0046] The second connecting gate line is located on an extension line of the first negative sub-gate line toward the fourth edge.

[0047] As an improvement of the above technical solution, the first PAD point is provided at the end of the first sub-positive electrode grid line and is electrically connected to the first sub-positive electrode grid line;

[0048] The second PAD test point is disposed at an end of the first sub-negative gate line and is electrically connected to the first sub-negative gate line.

[0049] As an improvement of the above technical solution, the positive grid line further includes a second sub-positive grid line arranged close to the first sub-positive grid line; the first PAD point is connected to the first sub-positive grid line and at least two second sub-positive grid lines;

[0050] The negative electrode grid line further includes a second sub-negative electrode grid line arranged close to the first sub-negative electrode grid line; the second PAD point is electrically connected to the first sub-negative electrode grid line and at least two second sub-negative electrode grid lines.

[0051] As an improvement of the above technical solution, at least one side of the first connecting gate line in the first direction is further provided with a third sub-negative gate line extending along the second direction, and the third sub-negative gate line is electrically connected to at least one negative gate line close to the first PAD point and is insulated from the first PAD point;

[0052] The second connecting grid line is further provided with a third sub-positive grid line extending along the second direction on at least one side of the first direction. The third sub-positive grid line is electrically connected to at least one positive grid line close to the second PAD point and is insulated from the second PAD point.

[0053] As an improvement of the above technical solution, the third negative sub-electrode grid line is located on an extension line of the first negative sub-electrode grid line connected to the second PAD point to the third edge; and / or

[0054] The third positive sub-grid line is located on an extension line of the first positive sub-grid line connected to the first PAD point toward the fourth edge.

[0055] As an improvement of the above technical solution, the first PAD point and the second PAD point are square, circular, triangular or irregular in shape.

[0056] As an improvement of the above technical solution, the first PAD point and the second PAD point are square, and their width is 0.1 mm to 1 mm.

[0057] As an improvement of the above technical solution, the second PAD portion includes a plurality of third PAD points and a plurality of fourth PAD points, and the plurality of third PAD points and the plurality of fourth PAD points are alternately arranged along the second direction.

[0058] As an improvement of the above technical solution, a second PAD portion is further provided in the first edge region and / or the second edge region; the second PAD portion includes a third PAD point and a fourth PAD point, the third PAD point is electrically connected to the positive electrode grid line, and the fourth PAD point is electrically connected to the negative electrode grid line;

[0059] A first PAD point and a second PAD point located in the first edge region are arranged in a row with a third PAD point and a fourth PAD point located in the first edge region;

[0060] The first PAD point and the second PAD point located in the second edge region are arranged in a row with the third PAD point and the fourth PAD point located in the second edge region.

[0061] Correspondingly, the present invention also discloses a battery string, which includes the above-mentioned back-contact solar cell.

[0062] Correspondingly, the present invention also discloses a battery assembly, which includes the above-mentioned back-contact solar cell or the above-mentioned battery string.

[0063] Correspondingly, the present invention also discloses a photovoltaic system, which includes the above-mentioned battery assembly.

[0064] The implementation of the present invention has the following beneficial effects:

[0065] In the back-contact solar cell of the present invention, a first sub-doped layer and a second sub-doped layer that form a leakage composite contact structure at a preset position are arranged on the back side of the silicon substrate to weaken the hot spot effect. Furthermore, a first PAD point and a second PAD point are electrically connected to the first sub-positive grid line corresponding to the first sub-doped layer and the first sub-negative grid line corresponding to the second sub-doped layer, respectively. Based on this embodiment, a reverse current can be passed through the first sub-PAD point and the second PAD point to the back-contact solar cell, and then the reverse breakdown voltage of the back-contact solar cell can be obtained by testing, which provides a good basis for characterizing the hot spot effect at the cell end. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a schematic diagram of the back structure of a back-contact solar cell in one embodiment of the present invention;

[0067] Figure 2 is a schematic diagram of the back structure of a back-contact solar cell in one embodiment of the present invention;

[0068] Figure 3is a schematic cross-sectional structure diagram of a back-contact solar cell in one embodiment of the present invention;

[0069] Figure 4 is a schematic diagram of the structure of the first doping layer and the second doping layer in one embodiment of the present invention;

[0070] Figure 5 is a schematic diagram of the back structure of a back-contact solar cell in one embodiment of the present invention;

[0071] Figure 6 is a schematic diagram of the back structure of a back-contact solar cell in one embodiment of the present invention;

[0072] Figure 7 is a schematic diagram of the back structure of a back-contact solar cell in one embodiment of the present invention;

[0073] Figure 8 is a schematic structural diagram of a back-contact solar cell string according to an embodiment of the present invention;

[0074] Fig. 9 is a schematic structural diagram of a back-contact solar cell string in another embodiment of the present invention;

[0075] Fig.10 is a schematic structural diagram of a back-contact solar cell assembly according to an embodiment of the present invention;

[0076] Fig.11 Schematic diagram of the composition of a photovoltaic system in one embodiment of the present invention. DETAILED DESCRIPTION

[0077] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0078] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0079] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0080] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0081] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0082] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the various specific processes and examples of materials provided in the present application, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0083] Embodiment 1

[0084] refer to Figure 1 to Figure 4 The back-contact solar cell 200 in this embodiment includes a silicon substrate 1, a plurality of first doped layers 21, a plurality of second doped layers 22, a plurality of positive electrode grid lines 31 and a plurality of negative electrode grid lines 32.

[0085] Among them, the silicon substrate 1 can be P-type single crystal silicon, N-type single crystal silicon, P-type polycrystalline silicon or N-type polycrystalline silicon, but not limited to this, preferably N-type single crystal silicon. In terms of thickness direction, the silicon substrate 1 includes a light-receiving surface 11 and a backlight surface 12 arranged relatively, wherein the light-receiving surface 11 generally refers to the side that receives light, and its surface may also be provided with a passivation layer, an anti-reflection layer, etc. commonly used in the art, but not limited to this. The backlight surface 12 is mainly provided with an electrode structure, and a passivation layer, etc. may also be provided, but not limited to this. It should be noted that in some embodiments, the backlight surface 12 may also absorb light incident through the backlight surface 12, thereby generating a photocurrent.

[0086] Wherein, the silicon substrate 1 may be circular, hexagonal, octagonal or rectangular, but is not limited thereto. Preferably, in one embodiment, the silicon substrate 1 is rectangular, and chamfers may be provided at its four corners. When the silicon substrate 1 is rectangular, it has a first edge 13 and a second edge 14 arranged oppositely in the first direction, and a third edge 15 and a fourth edge 16 arranged oppositely in the second direction. Wherein, the first direction and the second direction intersect. In one embodiment, the first direction may be a lateral direction, and the second direction may be a vertical direction, wherein the first direction and the second direction are perpendicular to each other. It is understood that in other embodiments, the first direction and the second direction may not be perpendicular, and the first direction and the second direction may also be other arbitrary directions, such as the diagonal direction of the rectangular silicon substrate 1, but are not limited thereto.

[0087] The first doping layer 21 and the second doping layer 22 are arranged on the backlight surface 12. Specifically, the first doping layer 21 and the second doping layer 22 are arranged alternately along the first direction and extend along the second direction. A spacing region 23 is provided between the first doping layer 21 and the second doping layer 22 to achieve insulation between the first doping layer 21 and the second doping layer 22. The first doping layer 21 may be one or more of a P-type doped polysilicon layer, a P-type doped amorphous silicon layer or a P-type doped microcrystalline silicon layer, but not limited thereto. Preferably, the first doping layer 21 is a P-type polycrystalline silicon layer; the P-type doping element in the first doping layer 21 may be B, Al or Ga, but not limited thereto, preferably B. The second doping layer 22 is an N-type doped polycrystalline silicon layer, an N-type doped amorphous silicon layer or an N-type doped microcrystalline silicon layer, but not limited thereto. Preferably, it is an N-type doped polycrystalline silicon layer. The N-type doping element in the second doping layer 22 may be P, As or Sb, but not limited thereto. Preferably, it is P.

[0088] The positive electrode grid line 31 may be a silver grid line, an aluminum grid line, a copper grid line, a silver-clad copper grid line or a copper-clad silver grid line, but is not limited thereto. The positive electrode grid line 31 may be formed by a screen printing process or by an electroplating process, or by a stacking grid process, but is not limited thereto. The positive electrode grid line 31 is disposed above the first doped layer 21 and contacts the first doped layer 21. Preferably, reference Figure 3In one embodiment, an insulating layer 40 is further provided between the positive gate line 31 and the first doped layer 21. The positive gate line 31 contacts the first doped layer 21 through a first hole 41 provided on the insulating layer 40. The first hole 41 can be formed by a laser process, an etching process, or a slurry burn-through process, but is not limited thereto.

[0089] The negative electrode grid line 32 may be a silver grid line, an aluminum grid line, a copper grid line, a silver-clad copper grid line or a copper-clad silver grid line, but is not limited thereto. The negative electrode grid line 32 may be formed by a screen printing process or by an electroplating process, or by a stacking grid process, but is not limited thereto. Preferably, reference Figure 3 In one embodiment, an insulating layer 40 is further provided between the negative electrode grid line 32 and the second doping layer 22, and the negative electrode grid line 32 contacts the second doping layer 22 through a second hole 42 provided on the insulating layer 40. The second hole 42 can be formed by a laser process, an etching process, or a slurry burn-through process, but is not limited thereto.

[0090] Specifically, refer to Figure 4 The first doping layer 21 includes at least one first sub-doping layer 211, and the second doping layer 22 includes at least one second sub-doping layer 221. The first sub-doping layer 211 and the second sub-doping layer 221 form a leakage composite contact structure 24 at a preset position. Based on the leakage composite contact structure 24, the reverse voltage at both ends of the back contact solar cell 200 under peak current can be reduced, the heating power can be reduced, the probability of hot spots occurring can be reduced, and the temperature of the hot spot area when the hot spot occurs can be reduced.

[0091] Specifically, in one embodiment, at a preset position, the first sub-doping layer 211 or the second sub-doping layer 221 may be extended to a doping layer of another polarity (such as the second sub-doping layer 221 or the first sub-doping layer 211), so that the two are in contact to form a leakage composite contact structure 24. In another embodiment, at a preset position, a functional layer with a conductive effect is formed so that the first sub-doping layer 211 and the second sub-doping layer 221 are in contact to form a leakage composite contact structure 24. In another embodiment, the leakage composite contact structure 24 may be formed by a stacked structure of the first sub-doping layer 211 and the second sub-doping layer 221, specifically, the second sub-doping layer 221 may be stacked on the first sub-doping layer 211, or the first sub-doping layer 211 may be stacked on the second sub-doping layer 221. It should be noted that when a stacked structure is adopted, a dielectric layer may be further provided between the first sub-doping layer 211 and the second sub-doping layer 221, and the dielectric layer may be a film layer with a tunneling effect, such as a silicon oxide tunneling passivation layer, but is not limited thereto. Preferably, at a preset position, a second sub-doping layer 221 is stacked on the first sub-doping layer 211 to form a leakage composite contact structure 24. Based on this structure, the leakage composite contact structure 24 can be formed by etching the second sub-doping layer 221, which is simple in process and highly reliable.

[0092] Specifically, the first doping layer 21 includes 5 to 20 first sub-doping layers 211, and the plurality of first sub-doping layers 211 are uniformly or unevenly distributed on the backlight surface 12 along the first direction. By controlling the number of the first sub-doping layers 211, the hot spot effect can be better controlled. Preferably, in one embodiment, the first doping layer 21 includes 5 to 20 first sub-doping layers 211, and the plurality of first sub-doping layers 211 are uniformly distributed along the first direction. It should be noted that in the back contact solar cell 200, a plurality of first doping layers 21 and second doping layers 22 are arranged on the back side thereof, wherein each first doping layer 21 / second doping layer 22 forms a PN unit with the silicon substrate 1, and the plurality of PN units are connected in parallel. By controlling the uniform distribution of the first sub-doping layer 211, the leakage composite contact structure 24 can be uniformly introduced between the plurality of PN units, thereby effectively reducing the probability of hot spots and reducing the temperature of the hot spot area when hot spots occur.

[0093] Specifically, in order to prevent the first positive sub-grid line 311 disposed on the first sub-doped layer 211 from contacting the second sub-doped layer 221 and forming a short circuit, the width of the first sub-doped layer 211 is set to be greater than the width of the first doped layer 21, or the first sub-doped layer 211 is widened only at a preset position. Specifically, the width of the first sub-doped layer 211 or the width of the widened portion thereof (in the first direction) is 0.8 mm to 1.5 mm, and the width of other first doped layers 21 (in the first direction) is 0.6 mm to 1 mm.

[0094] Optionally, after increasing the width of the first sub-doping layer 211, in order to improve the carrier collection efficiency, the width of the first sub-positive electrode grid line 311 is controlled to be greater than the width of other positive electrode grid lines 31. Specifically, the width of the first sub-positive electrode grid line 311 is 50μm to 200μm, and the width of other positive electrode grid lines 31 is 30μm to 200μm.

[0095] Accordingly, reference Figure 1 and Figure 2In this embodiment, the back-contact solar cell 200 includes at least one group of first PAD parts, each group of first PAD parts includes a first PAD point 51 and a second PAD point 52, the first PAD point 51 is electrically connected to the first sub-positive grid line 311, and the second PAD point 52 is electrically connected to the first sub-negative grid line 321. A reverse current is injected into the back-contact solar cell 200 through the first PAD point 51 and the second PAD point 52, and flows through the leakage composite contact structure 24, and the reverse breakdown voltage of the back-contact solar cell 200 is obtained by testing, which provides a good basis for characterizing the hot spot effect at the battery end. It should be noted that the conventional hot spot test is generally performed at the component 600 end, that is, any one or more solar cell slices in the solar cell component 600 are blocked, and other solar cells (or slices) are exposed to light. After a period of time, the temperature of the blocked solar cell (or slice) is tested to characterize the hot spot effect. It is difficult for the existing technology to accurately quantify the hot spot effect at the battery end. After introducing the leakage composite contact structure 24, this embodiment measures its reverse breakdown voltage, which fully expresses the influence of the leakage composite contact structure 24 on the reverse breakdown voltage, and then quantitatively characterizes the hot spot effect through the reverse breakdown voltage, providing a good basis for controlling the hot spot effect of the component 600.

[0096] It is understandable that the first PAD point 51 and the second PAD point 52 do not contact the first doping layer 21 and the second doping layer 22 thereunder to prevent leakage. That is, an insulating layer 40 is provided between the first PAD point 51 and the second PAD point 52 and the first doping layer 21 and the second doping layer 22. The insulating layer 40 may include one or more of an aluminum oxide layer, an amorphous silicon layer, a silicon oxide layer, and a silicon nitride layer.

[0097] Wherein, the first PAD point 51 and the second PAD point 52 are square, circular, triangular or irregular in shape, but are not limited thereto. Preferably, in one embodiment, the first PAD point 51 and the second PAD point 52 are square in shape, and their width is 0.1 mm to 1 mm. Based on this width, the first PAD point 51 and the second PAD point 52 can form good contact with the test probe of the test device. Wherein, the test probe refers to a probe used to inject current in the test equipment.

[0098] Specifically, refer to Figure 1 and Figure 2In this embodiment, along the direction from the first edge 13 of the silicon substrate 1 to the second edge 14, the backlight surface 12 includes a first edge region 110, a middle region 120, and a second edge region 130, and the first PAD portion is disposed in the middle region 120. More specifically, based on this embodiment, a second PAD portion is further disposed in the first edge region 110 and the second edge region 130, and the second PAD portion includes a third PAD point 53 and a fourth PAD point 54, the third PAD point 53 is electrically connected to the positive electrode grid line 31, and the fourth PAD point 54 is electrically connected to the negative electrode grid line 32. The second PAD portion can be used for welding later.

[0099] Specifically, in the present embodiment, the first PAD point 51 of the first PAD portion provided in the middle area 120 is arranged close to the third edge 15, and the second PAD point 52 is arranged close to the fourth edge 16. Based on this embodiment, problems such as printing cracks caused by the first PAD portion being too close to the edge can be avoided. Specifically, the distance between the first PAD point 51 and the third edge 15 is 1mm to 10mm, exemplarily 1.5mm, 3mm, 4.5mm, 6mm, 7.5mm or 9mm, but not limited thereto. The distance between the second PAD point 52 and the fourth edge 16 is 1mm to 9mm, exemplarily 1.5mm, 3mm, 4.5mm, 6mm, 7.5mm or 9mm, but not limited thereto. Specifically, the distance between the first PAD point 51 and the third edge 15 refers to the distance between the geometric center of the first PAD point 51 and the third edge 15. The distance between the second PAD point 52 and the fourth edge 16 refers to the distance between the geometric center of the second PAD point 52 and the fourth edge 16.

[0100] Specifically, in one embodiment, refer to Figure 1 , the first doping layer 21 includes 5 to 20 first sub-doping layers 211, each of which is provided with a first sub-positive gate line 311, each of which is in contact with the first sub-doping layer 211 and insulated from the second sub-doping layer 221. Correspondingly, a first PAD point 51 is connected to each first sub-positive gate line 311. The second doping layer 22 includes 5 to 20 second sub-doping layers 221, each of which is provided with a first sub-negative gate line 321, and each of which is connected to a second PAD point 52. That is, in this embodiment, each PN unit provided with a leakage composite contact structure 24 is provided with a first PAD portion, which can effectively improve the test accuracy.

[0101] In another embodiment, the first doping layer 21 includes 5 to 20 first sub-doping layers 211, each of which is provided with a first sub-positive gate line 311, each of which is in contact with the first sub-doping layer 211 and insulated from the second sub-doping layer 221. Correspondingly, a first PAD point 51 is connected to each first sub-positive gate line 311. The second doping layer 22 includes 10 to 40 second sub-doping layers 221, that is, a second sub-doping layer 221 is provided on both sides of each first sub-doping layer 211. Each second sub-doping layer 221 is provided with a first sub-negative gate line 321, each of which is in contact with the second sub-doping layer 221 and insulated from the first sub-doping layer 211. That is, in this embodiment, a first sub-negative gate line 321 is provided on both sides of each first sub-positive gate line 311. Based on this embodiment, for each first negative sub-gate line 321 corresponding to the first positive sub-gate line 311, the first negative sub-gate line 321 on any side may be connected to the second PAD point 52, or both first negative sub-gate lines 321 may be connected to the same second PAD point 52. In this embodiment, each PN unit provided with a leakage composite contact structure 24 is provided with a first PAD portion, which can effectively improve the test accuracy.

[0102] It should be noted that although increasing the number of the first PAD portion will optimize the accuracy of the test results, it will also occupy the grid line space, reduce carrier collection, and reduce the conversion efficiency of the back contact solar cell 200. Figure 2 In one embodiment, a first PAD point 51 is set for every other first positive sub-grid line 311, and correspondingly, a second PAD point 52 is set for every other first negative sub-grid line 321. Based on the above embodiments, the conversion efficiency can be improved while ensuring the most accurate test accuracy.

[0103] Furthermore, considering conversion efficiency and test accuracy, the number of first PAD parts is set to 1 to 12 groups, exemplarily 1, 3, 5, 7 or 9 groups, but not limited thereto, preferably 1 to 4 groups.

[0104] The influence of the number of the first PAD parts on the reverse breakdown voltage test results is further described below:

[0105] For an ideal diode, the current can be calculated as follows:

[0106]

[0107] In the formula, I DD is the current flowing from the positive electrode to the negative electrode in an ideal diode, I sis the reverse saturation current of the ideal diode; n is the emission coefficient, which is 1 to 2; k is the Boltzmann constant, T is the temperature, q is the space electron charge, and V is the voltage across the positive and negative electrodes of the ideal diode.

[0108] After the leakage composite contact structure 24 is introduced, the current of the diode with leakage current can be calculated by the following formula:

[0109]

[0110] Among them, I D is the output current of the diode with leakage current, I DD is the current flowing from the positive electrode to the negative electrode in an ideal diode, I S is the reverse saturation current of the ideal diode, n is the emission coefficient, which is 1 to 2; k is the Boltzmann constant, T is the temperature, q is the space electron charge, V is the voltage across the positive and negative electrodes of the diode, I S,R is the reverse saturation current of the diode with leakage current, n R is the leakage emission coefficient, n R ≥2.

[0111] Under non-ideal conditions, the diode can be reversely broken down, and the reverse breakdown current I D,BR It can be expressed as:

[0112]

[0113] Among them, I BR is the breakdown inflection point current; V is the voltage across the positive and negative electrodes of the diode, V BR is the reverse breakdown voltage, n BR is the breakdown emission coefficient, and its value range is 0.95~1.02.

[0114] Therefore, when the series resistance (ie, the gate line resistance and the contact resistance between the gate line and the doping layer) is not taken into account, the current in the back-contact solar cell 200 of this embodiment can be calculated by the following formula:

[0115]

[0116] In actual testing, due to the voltage division of series resistance (gate line resistance, contact resistance between gate line and doping layer), when the external voltage is V W When the line resistance of a pitch (PN unit) gate line transmission is R s , x is the number of pitches through which the transmission current passes, and the gate line has good contact with the doped layer, and the contact resistance is extremely small, then the voltage across the minimum unit diode is V = V w -xI D R s .

[0117] Then, after taking into account the series resistance, the current of a single PN unit in the back contact battery in this embodiment can be calculated by the following formula:

[0118]

[0119] Where V W is the applied voltage, R s is the line resistance of the gate line transmission of a pitch (PN unit), x is a variable representing the number of pitches between the positive gate line 31 and the first PAD point 51, and Figure 7 For example, there are 6 first doping layers 21 and 6 second doping layers 22 between adjacent first PAD points 51 / second PAD points 52 , for a total of 6 PN units, then x=6÷2=3.

[0120] Here, it should be noted that in this embodiment, a plurality of first doping layers 21 and second doping layers 22 are arranged on the back of the back contact cell, which form a plurality of PN units with the silicon substrate 11 , and it can be approximately considered that the plurality of PN units are connected in parallel.

[0121] Therefore, when only one set of the first PAD portion is provided on the back contact solar cell 200 having z PN units (pitch), the measured current and voltage can be calculated by the following formula:

[0122]

[0123] Among them, I D2 is the current measured when setting a first PAD part, V C2 is the voltage measured when a group of first PAD parts is set.

[0124] If four first PADs are set, the measured current and voltage can be calculated by the following formula:

[0125]

[0126] Among them, I D5 is the current measured when setting the first PAD part of the four groups, V C5 It is the voltage measured when four groups of the first PAD parts are set.

[0127] From the above two equations, we can undoubtedly find that: D5 >I D2 Therefore, for the same back-contact solar cell 200 to be tested, V C5 <V C2. That is, when the first PAD part is increased, the test result of the reverse breakdown voltage is more accurate. In addition, increasing the number of test points can reduce the test error caused by the first shunt gate line 61 / the second shunt gate line 62 and other broken gates. However, as mentioned above, increasing the first test point is not conducive to the improvement of conversion efficiency. To this end, the inventors have conducted a large number of tests based on the above analysis and proposed a specific correction method. Specifically, after the first PAD part of any group is tested, it can be converted according to the following formula:

[0128]

[0129] Among them, U rev is the reverse breakdown voltage of the back contact solar cell 200, U rev0 is the tested reverse breakdown voltage of the back-contact solar cell 200, x is the total number of the positive grid lines 31 and the negative grid lines 32, x0 is a variable characterizing the first PAD portion, x1 is the number of the first PAD points 51, x2 is the number of the second PAD points 52, A is a constant, and its value range is 0.1 to 3.3, and B is a constant, and its value range is 2 to 50.

[0130] Based on the above relationship, when setting any group of first PAD parts, the test results can be corrected to obtain an accurate reverse breakdown voltage. Specifically, it is found that when setting 1 to 4 groups of first PAD parts, the test error is ≤5%, when setting 4 to 6 groups, the test error is ≤3.5%, and when setting 8 to 10 groups, the test error is ≤1.5%.

[0131] Among them, in one embodiment, reference Figure 4 The back-contact solar cell 200 also includes a first shunt gate line 61 and a second shunt gate line 62, the first shunt gate line 61 is electrically connected to a plurality of positive gate lines 31, and the second shunt gate line 62 is electrically connected to a plurality of negative gate lines 32; the first shunt gate line 61 is electrically connected to the first PAD point 51, and the second shunt gate line 62 is electrically connected to the second PAD point 52; based on the above embodiment, the reverse current from the second PAD point 52 is shunted to a plurality of negative gate lines 32 via the second shunt gate line 62, and then flows through a plurality of positive gate lines 31 and then converges to the first PAD point 51 via the first shunt gate line 61, thereby achieving the effect of better characterizing the influence of gate line resistance voltage division and contact resistance voltage division on the accuracy of reverse breakdown voltage test. In addition, it should be noted that: when the number of groups of the first PAD points 51 set is small, the number of PN units passing through will also be reduced accordingly. Although this test value can also characterize the hot spot effect of the back-contact solar cell 200 to a certain extent, it is not accurate enough. By introducing the first shunt gate line 61 and the second shunt gate line 62, the reverse current can flow through more PN units, thereby effectively improving the accuracy of the test.

[0132] The first shunt grid line 61 and the second shunt grid line 62 may be in a straight line or a curved line, and may be arranged parallel to the first direction or at an angle with the first direction, but are not limited thereto. Preferably, in one embodiment, the first shunt grid line 61 and the second shunt grid line 62 are in a straight line and extend along the first direction, that is, they are parallel to the first direction, which reduces the length of the first shunt grid line 61 and the second shunt grid line 62 between the positive grid line 31 to be connected or the negative grid line 32 to be connected, and simplifies the grid line arrangement.

[0133] Preferably, in one embodiment, the width of the first shunt grid line 61 is controlled to be greater than the width of the positive grid line 31, and the width of the second shunt grid line 62 is controlled to be greater than the width of the negative grid line 32, so as to reduce the current loss of the first shunt grid line 61 and the second shunt grid line 62, thereby improving the test accuracy. More preferably, the width of the first shunt grid line 61 is 1.5 to 3 times the width of the positive grid line 31, and the width of the second shunt grid line 62 is 1.5 to 3 times the width of the negative grid line 32.

[0134] Among them, in one embodiment, the first shunt gate line 61 is arranged near the third edge 15, and the second shunt gate line 62 is arranged near the fourth edge 16. Based on this arrangement, the gate line structure can be simplified, the carrier collection efficiency can be improved, and the conversion efficiency can be improved. Since the first shunt gate line 61 / the second shunt gate line 62 connects multiple positive gate lines 31 / negative gate lines 32 extending in the second direction, if the first shunt gate line 61 / the second shunt gate line 62 is arranged in the center, multiple discontinuous insulation structures or other types of insulation structures need to be arranged in the gate line areas with different polarities, the gate line structure is complicated, and the arrangement area of ​​the positive gate line 31 and the negative gate line 32 is reduced, which reduces the collection of carriers.

[0135] Specifically, the distance between the first shunt grid line 61 and the third edge 15 is 0.1 mm to 3 mm, exemplarily 0.5 mm, 1 mm, 1.5 mm, 2 mm or 2.5 mm, but not limited thereto. Specifically, the distance between the first shunt grid line 61 and the third edge 15 refers to the distance between the center line of the first shunt grid line 61 and the third edge 15. The distance between the second shunt grid line 62 and the fourth edge 16 is 0.1 mm to 3 mm, exemplarily 0.5 mm, 1 mm, 1.5 mm, 2 mm or 2.5 mm, but not limited thereto. Specifically, the distance between the second shunt grid line 62 and the fourth edge 16 refers to the distance between the center line of the second shunt grid line 62 and the fourth edge 16.

[0136] Preferably, in one embodiment, the first shunt grid line 61 is arranged at the end of the positive grid line 31 close to the third edge 15, that is, the positive grid line 31 and the negative grid line 32 are arranged on the side of the first shunt grid line 61 facing the fourth edge 16; and no other grid lines are arranged between the first shunt grid line 61 and the third edge 15. Based on the above arrangement, the carrier collection area can be widened and the conversion efficiency of the back contact solar cell 200 can be improved. In addition, the accuracy of the reverse breakdown voltage can also be improved.

[0137] Correspondingly, in one embodiment, the second shunt gate line 62 is arranged at the end of the negative gate line 32 close to the fourth edge 16, that is, the positive gate line 31 and the negative gate line 32 are arranged on the side of the second shunt gate line 62 facing the third edge 15, and no other gate lines are arranged between the second shunt gate line 62 and the fourth edge 16 to improve conversion efficiency and test accuracy.

[0138] It can be expected that the first shunt grid line 61, the second shunt grid line 62 and the doped layer are not in contact, because the first shunt grid line 61, the second shunt grid line 62 extend along the first direction, and the positive grid line 31, the negative grid line 32 extend along the second direction, and the two are perpendicular to each other. If the first shunt grid line 61 and the second shunt grid line 62 are opened, the laser opening efficiency will be affected. Therefore, the first shunt grid line 61 and the second shunt grid line 62 area are not opened and contacted with the doped layer, and they only play the role of shunting / converging. At the same time, it can be understood that by increasing the number of settings of the first PAD point 51 and the second PAD point 52, the influence of the first shunt grid line 61 / the second shunt grid line 62 broken gate on the test results can also be reduced.

[0139] Specifically, in one embodiment, when the first PAD point 51 and the first shunt gate line 61 are both set close to the third edge 15, the distance between the first PAD point 51 and the third edge 15 is controlled to be greater than the distance between the first shunt gate line 61 and the third edge 15. Since the first PAD point 51 is relatively large and is too close to the third edge 15, defects such as hidden cracks are easily caused during printing. Moreover, by controlling the first shunt gate line 61 to be closer to the third edge 15, a spacing area is formed between the first shunt gate line 61 and the first PAD point 51, and a gate line can be set in the spacing area to further improve the collection efficiency of carriers and improve the conversion efficiency. Specifically, based on this embodiment, the distance between the first PAD point 51 and the third edge 15 is controlled to be 3mm to 8mm, and the distance between the first shunt gate line 61 and the third edge 15 is 0.2mm to 5mm.

[0140] Specifically, when a spacing area is formed between the first shunt gate line 61 and the first PAD point 51, the first shunt gate line 61 can be electrically connected to the first PAD point 51 through the first connecting gate line 71. Preferably, in one embodiment, the first connecting gate line 71 is located on the extension line of the first sub-positive gate line 311 to the third edge 15; that is, the first connecting gate line 71 is arranged above the first sub-doping layer 211 corresponding to the first sub-positive gate line 311, and then the first connecting gate line 71 can be connected to the first sub-doping layer 211 through the first hole 41, so that the first connecting gate line 71 can also collect carriers to improve the conversion efficiency.

[0141] Correspondingly, in one embodiment, when the second PAD point 52 and the second shunt gate line 62 are both set close to the fourth edge 16, the distance between the second PAD point 52 and the fourth edge 16 is controlled to be greater than the distance between the second shunt gate line 62 and the fourth edge 16. Since the second PAD point 52 is relatively large and is too close to the fourth edge 16, defects such as hidden cracks are easily caused during printing. Moreover, by controlling the second shunt gate line 62 to be closer to the fourth edge 16, a spacing area is formed between the second shunt gate line 62 and the second PAD point 52, and a gate line can be set in the spacing area to further improve the collection efficiency of carriers and improve the conversion efficiency. Specifically, based on this embodiment, the distance between the second PAD point 52 and the fourth edge 16 is controlled to be 3mm to 8mm, and the distance between the second shunt gate line 62 and the fourth edge 16 is 0.2mm to 5mm.

[0142] Specifically, when a spacing area is formed between the second shunt gate line 62 and the second PAD point 52, the second shunt gate line 62 can be electrically connected to the second PAD point 52 through the second connection gate line 72. Preferably, in one embodiment, the second connection gate line 72 is located on the extension line of the first sub-negative gate line 321 to the fourth edge 16; that is, the second connection gate line 72 is arranged above the second sub-doped layer 221 corresponding to the first sub-negative gate line 321, and then the second connection gate line 72 can be connected to the second sub-doped layer 221 through the second hole 42, so that the second connection gate line 72 can also collect carriers to improve the conversion efficiency.

[0143] Specifically, in one embodiment, the positive grid line 31 also includes a second sub-positive grid line 312 disposed near the first sub-positive grid line 311; the first PAD point 51 is connected to the first sub-positive grid line 311 and at least two second sub-positive grid lines 312; the negative grid line 32 also includes a second sub-negative grid line 322 disposed near the first sub-negative grid line 321; the second PAD point 52 is electrically connected to the first sub-negative grid line 321 and at least two second sub-negative grid lines 322. Although the first PAD point 51 / the second PAD point 52 can distribute the reverse current through the first shunt grid line 61 / the second shunt grid line 62, the first shunt grid line 61 / the second shunt grid line 62 is narrow, and when the current density is too large, more is consumed. For this reason, the first PAD point 51 / the second PAD point 52 is connected to at least three positive grid lines 31 / the negative grid lines 32 to optimize the current distribution and improve the test accuracy. More preferably, the first PAD point 51 is electrically connected to one first sub-positive gate line 311 and two second sub-positive gate lines 312; the second PAD point 52 is electrically connected to one first sub-negative gate line 321 and two second sub-negative gate lines 322. When the number of connected gate lines is too large, the sizes of the first PAD point 51 and the second PAD point 52 are too large, occupying more area of ​​the gate lines for collecting carriers, which is not conducive to improving the conversion efficiency.

[0144] Preferably, in one embodiment, a third sub-negative gate line 323 extending along the second direction is further provided on at least one side of the first connecting gate line 71 in the first direction, and the third sub-negative gate line 323 is electrically connected to at least one negative gate line 32 close to the first PAD point 51, and is insulated from the first PAD point 51; through the third sub-negative gate line 323, carriers in the gap area between the first shunt gate line 61 and the first test PAD point can be collected to improve the conversion efficiency. More preferably, in order to collect more carriers, the third sub-negative gate line 323 is arranged on the extension line of the first sub-negative gate line 321 or the second sub-negative gate line 322 connected to the second PAD point 52 to the third edge 15; that is, the third sub-negative gate line 323 is arranged above the second doped layer 22 corresponding to the first sub-negative gate line 321 or the second sub-negative gate line 322, and then the third sub-negative gate line 323 is connected to the second doped layer 22 through the second hole 42, so that the third sub-negative gate line 323 collects more carriers and improves the conversion efficiency.

[0145] Correspondingly, in one embodiment, a third positive sub-grid line 313 extending along the second direction is further provided on at least one side of the second connection grid line 72 in the first direction, and the third positive sub-grid line 313 is electrically connected to at least one positive grid line 31 close to the second PAD point 52, and is insulated from the second PAD point 52. The third positive sub-grid line 313 can collect carriers in the gap between the second shunt grid line 62 and the second test PAD point, thereby improving conversion efficiency. More preferably, in order to collect more carriers, the third sub-positive gate line 313 is arranged on the extension line of the first sub-positive gate line 311 or the second sub-positive gate line 312 connected to the first PAD point 51 to the fourth edge 16; that is, the third sub-positive gate line 313 is arranged above the first doped layer 21 corresponding to the first sub-positive gate line 311 or the second sub-positive gate line 312, and then the third sub-positive gate line 313 is connected to the first doped layer 21 through the first hole 41 to collect more carriers and improve the conversion efficiency.

[0146] Specifically, in this embodiment, each group of second PAD portions includes a third PAD point 53 and a fourth PAD point 54, wherein the third PAD point 53 is electrically connected to at least one positive electrode grid line 31 and is insulated from the negative electrode grid line 32. The fourth PAD point 54 is electrically connected to at least one negative electrode grid line and is insulated from the positive electrode grid line 31. That is, the third PAD point 53 is used to connect the positive electrode welding strip 300, and the fourth PAD point 54 is used to form the negative electrode welding strip 300.

[0147] Specifically, in this embodiment, each group of second PAD portions may include 1 to 20 third PAD points 53 and 1 to 20 fourth PAD points 54. Preferably, the number of the third PAD points 53 is 8 to 20, more preferably 12 to 20. Preferably, the number of the fourth PAD points 54 is 8 to 20, more preferably 12 to 20.

[0148] Specifically, when a group of second PAD portions includes a plurality of third PAD points 53 and a plurality of fourth PAD points 54, the third PAD points 53 and the fourth PAD points 54 are alternately arranged along the second direction. Based on this arrangement relationship, the current transmission distance can be further optimized, the loss can be reduced, and the power can be increased. Furthermore, in order to simplify the electrode pattern and reduce the printing stress, the plurality of third PAD points 53 and the fourth PAD points 54 in the same group are arranged in a row in the second direction.

[0149] The third PAD point 53 and the fourth PAD point 54 are square, circular, triangular or irregular in shape, but are not limited thereto. Preferably, in one embodiment, the third PAD point 53 and the fourth PAD point 54 are square in shape, and their width is 0.1 mm to 1 mm. Based on this width, the welding tension can be ensured to be appropriate, thereby improving reliability.

[0150] Embodiment 2

[0151] This embodiment provides a back contact solar cell. Figure 5 , which is different from Example 1 in that:

[0152] The first PAD portion is only disposed in the first edge region 110 and / or the second edge region 130 . The first PAD portion includes a first PAD point 51 and a second PAD point 52 .

[0153] Specifically, the first sub-doping layer 211 and the second sub-doping layer 221 may be disposed in the first edge region 110 / the second edge region 130, the first sub-positive grid line 311 is disposed above the first sub-doping layer 211, and the second sub-positive grid line 312 is disposed above the second sub-doping layer 221. Then, the first PAD point 51 is connected to the end of the first sub-positive grid line 311 close to the third edge 15, and the second PAD point 52 is connected to the end of the first sub-negative grid line 321 close to the fourth edge 16.

[0154] Specifically, based on this embodiment, a second PAD portion is further provided in the first edge region 110 and / or the second edge region 130. The second PAD portion includes a plurality of third PAD points 53 and a plurality of fourth PAD points 54. The third PAD points 53 and the fourth PAD points 54 are alternately arranged along the second direction.

[0155] Furthermore, based on this embodiment, the first PAD point 51, the second PAD point 52, the third PAD point 53, and the fourth PAD point 54 located in the first edge area 110 / the second edge area 130 can be arranged in a row, that is, the first PAD point 51 and the second PAD point 52 can be used for welding, thereby increasing the welding tension and further reducing the influence of the first PAD part on carrier collection, thereby improving the conversion efficiency.

[0156] Further, based on this embodiment, in order to further optimize the test accuracy, the remaining multiple first sub-positive grid lines 311 are electrically connected to the first PAD point 51 through the first shunt grid line 61, and the remaining multiple first sub-negative grid lines 321 are electrically connected to the second PAD point 52 through the second shunt grid line 62. More preferably, all positive grid lines 31 can be electrically connected through the first shunt grid line 61, and all negative grid lines 32 can be electrically connected through the second shunt grid line 62.

[0157] Embodiment 3

[0158] This embodiment provides a back contact solar cell. Figure 6 , which is different from Example 1 in that:

[0159] The first PAD portion is only disposed in the first edge region 110 and / or the second edge region 130 . The first PAD portion includes a first PAD point 51 and a second PAD point 52 .

[0160] Specifically, in the present embodiment, the first sub-doping layer 211 and the second sub-doping layer 221 are not provided in the first edge region 110 / the second edge region 130, that is, the first sub-positive grid line 311 and the first sub-negative grid line 321 are not provided in the first edge region 110 / the second edge region 130. Based on this embodiment, the first PAD point 51 can be provided at the end of the positive grid line 31 provided in the first edge region 110 / the second edge region 130, which is close to the third edge 15, and it is electrically connected to the first sub-positive grid line 311 through the first shunt grid line 61. Similarly, the second PAD point 52 can be provided at the end of the negative grid line 32 provided in the first edge region 110 / the second edge region 130, which is close to the fourth edge 16, and it is electrically connected to the second sub-negative grid line 322 through the second shunt grid line 62. More preferably, based on this embodiment, all positive electrode grid lines 31 can be electrically connected via the first shunt grid line 61 , and all negative electrode grid lines 32 can be electrically connected via the second shunt grid line 62 .

[0161] Specifically, based on this embodiment, a second PAD portion is further provided in the first edge region 110 and / or the second edge region 130. The second PAD portion includes a plurality of third PAD points 53 and a plurality of fourth PAD points 54. The third PAD points 53 and the fourth PAD points 54 are arranged alternately along the second direction. It should be noted that since a large number of third PAD points 53 and fourth PAD points 54 are provided in the first edge region 110 / the second edge region 130, and the third PAD point 53 needs to contact the positive gate line, if the first sub-positive gate line 311 is provided in the first edge region 110 / the second edge region 130, due to the presence of a composite leakage contact structure, the third PAD point 53 is more likely to contact the second doping layer 22, and leakage may occur, so the first sub-positive gate line 311 and the second sub-negative gate line 322 are not provided in this area. In addition, since the area near the edge often produces more defects than the central area during the preparation of the back contact battery, the leakage composite contact structure 24 is prone to overall failure when it is set in this area, and it is difficult to play a role in weakening the hot spot effect in the long term.

[0162] Furthermore, based on this embodiment, the first PAD point 51, the second PAD point 52, the third PAD point 53, and the fourth PAD point 54 located in the first edge area 110 / the second edge area 130 can be arranged in a row, that is, the first PAD point 51 and the second PAD point 52 can be used for welding, thereby increasing the welding tension and further reducing the influence of the first PAD part on carrier collection, thereby improving the conversion efficiency.

[0163] Embodiment 4

[0164] This embodiment provides a back contact solar cell 200, referring to Figure 7 The difference between the embodiment 1 and the embodiment 1 is that a first PAD portion is also provided in the first edge region 110 / the second edge region 130 , and the first PAD portion also includes a first PAD point 51 and a second PAD point 52 .

[0165] Specifically, in one embodiment, the first sub-doping layer 211 and the second sub-doping layer 221 may be provided in the first edge region 110 / the second edge region 130, the first sub-positive grid line 311 is provided above the first sub-doping layer 211, and the second sub-positive grid line 312 is provided above the second sub-doping layer 221. Then, the first PAD point 51 is connected to the end of the first sub-positive grid line 311 close to the third edge 15, and the second PAD point 52 is connected to the end of the first sub-negative grid line 321 close to the fourth edge 16. Further, based on this embodiment, in order to further optimize the test accuracy, the remaining multiple first sub-positive grid lines 311 are electrically connected to the first PAD point 51 through the first shunt grid line 61, and the remaining multiple first sub-negative grid lines 321 are electrically connected to the second PAD point 52 through the second shunt grid line 62. More preferably, all positive pole grid lines 31 may be electrically connected via the first shunt grid line 61 , and all negative pole grid lines 32 may be electrically connected via the second shunt grid line 62 .

[0166] Specifically, in another embodiment, the first sub-doping layer 211 and the second sub-doping layer 221 are not provided in the first edge region 110 / the second edge region 130, that is, the first sub-positive grid line 311 and the first sub-negative grid line 321 are not provided in the first edge region 110 / the second edge region 130. Based on this embodiment, the first PAD point 51 can be provided at the end of the positive grid line 31 provided in the first edge region 110 / the second edge region 130, which is close to the third edge 15, and it is electrically connected to the first sub-positive grid line 311 through the first shunt grid line 61. Similarly, the second PAD point 52 can be provided at the end of the negative grid line 32 provided in the first edge region 110 / the second edge region 130, which is close to the fourth edge 16, and it is electrically connected to the second sub-negative grid line 322 through the second shunt grid line 62. More preferably, based on this embodiment, all positive electrode grid lines 31 can be electrically connected via the first shunt grid line 61 , and all negative electrode grid lines 32 can be electrically connected via the second shunt grid line 62 .

[0167] Embodiment 5

[0168] refer to Figure 8 and Fig. 9This embodiment provides a battery string 400, which includes a plurality of back-contact solar cells 200 according to Embodiments 1 to 4 of the present invention, or slices formed by cutting the back-contact solar cells 200.

[0169] Specifically, in one embodiment, refer to Figure 8 Adjacent back-contact solar cells 200 (or their segments) can be overlapped to form a cell string 400, and connected in series or in parallel through a soldering ribbon 300 or a conductive adhesive, but the invention is not limited thereto.

[0170] In another embodiment, reference Fig. 9 , adjacent back-contact solar cells 200 (or their segments) can be connected in series or in parallel through welding strips 300 and conductive glue, but not limited to this. Correspondingly, since positive grid lines 31 and negative grid lines 32 are arranged on the back of the back-contact solar cell, in order to prevent the welding strips 300 from short-circuiting the two, it is also necessary to introduce insulating glue or insulating blocks, but not limited to this. In order to meet the fixation of the welding strips 300, it is also necessary to introduce adhesive glue (exemplary such as UV glue), solder paste, etc. In order to achieve the fixation of the back-contact solar cells 200 of the battery string 400, adhesive glue, etc. will also be introduced, but not limited to this.

[0171] Embodiment 6

[0172] refer to Fig.10 , this embodiment provides a battery assembly 600, which includes at least one battery string 400 as in Example 5 or at least one back-contact solar cell 200 as in Examples 1 to 4. Preferably, in one embodiment, the battery assembly 600 is composed of a plurality of the above-mentioned battery strings 400, exemplarily 2 strings, 4 strings, 6 strings or 12 strings, but not limited thereto. A plurality of battery strings 400 can be connected in series or in parallel through a bus bar 500, a welding ribbon 300 or other conductive media to form a battery assembly 600. In addition, in order to mechanically connect a plurality of battery strings 400, other use requirements of the assembly 600 (such as electrical connection of a plurality of battery assemblies 600, weather resistance, etc.), it is also necessary to introduce components such as insulating glue, junction boxes, frames, back panels, adhesive films, glass, etc., but not limited thereto.

[0173] Embodiment 7

[0174] refer to Fig.11 This embodiment provides a photovoltaic system, which includes the battery assembly 600 described in the sixth embodiment. A plurality of battery assemblies 600 can be connected in series or in parallel through a junction box to form a photovoltaic system. The photovoltaic system can be used in photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be used in equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc., but is not limited thereto.

[0175] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0176] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A back contact solar cell, characterized in that: include: A silicon substrate, comprising a light-receiving surface and a backlight surface that are arranged opposite to each other; A plurality of first doping layers and a plurality of second doping layers are arranged on the backlight surface, the plurality of first doping layers and the plurality of second doping layers are alternately arranged along a first direction and extend along a second direction; the first doping layer includes at least one first sub-doping layer, the second doping layer includes a second sub-doping layer arranged adjacent to the first sub-doping layer; the second sub-doping layer and the first sub-doping layer form a leakage composite contact structure at a preset position; A plurality of positive gate lines and a plurality of negative gate lines, wherein the positive gate lines are arranged on the first doped layer, and the negative gate lines are arranged on the second doped layer; the positive gate lines include a first sub-positive gate line arranged on the first sub-doped layer, and the negative gate lines include a first sub-negative gate line arranged on the second sub-doped layer; At least one group of first PAD parts, each group of the first PAD parts includes a first PAD point and a second PAD point, the first PAD point is electrically connected to the first sub-positive gate line, and the second PAD point is electrically connected to the first sub-negative gate line.

2. The back contact solar cell according to claim 1, characterized in that: The silicon substrate has a first edge and a second edge arranged opposite to each other in a first direction; along the direction from the first edge to the second edge, the backlight surface includes a first edge region, a middle region and a second edge region; The first PAD portion is disposed in the first edge region and the second edge region; or The first PAD portion is disposed in the middle area; or The first PAD portion is disposed in the first edge region, the middle region, and the second edge region.

3. The back contact solar cell according to claim 2, characterized in that: The first PAD portion is only disposed in the first edge region and the second edge region.

4. The back contact solar cell according to claim 2 or 3, characterized in that: A second PAD portion is further provided in the first edge region and / or the second edge region; The second PAD portion includes a third PAD point and a fourth PAD point, the third PAD point is electrically connected to the positive gate line, and the fourth PAD point is electrically connected to the negative gate line.

5. The back contact solar cell according to claim 4, characterized in that: The silicon substrate has a third edge and a fourth edge which are arranged opposite to each other in the second direction; A first PAD point of a first PAD portion disposed in the first edge region and the second edge region is disposed close to the third edge, and a second PAD point of a first PAD portion disposed in the first edge region and the second edge region is disposed close to the fourth edge; No third PAD point or fourth PAD point is set between the first PAD point and the third edge; No third PAD point or fourth PAD point is arranged between the second PAD point and the fourth edge.

6. The back contact solar cell according to claim 2, characterized in that: A first PAD point of the first PAD portion disposed in the middle region is disposed close to the third edge, and a second PAD point of the first PAD portion disposed in the middle region is disposed close to the fourth edge.

7. The back contact solar cell according to claim 1, characterized in that: The first doping layer includes 5 to 20 first sub-doping layers, each of which is provided with a first sub-positive electrode grid line, and each of which is connected to a first PAD point; The second doping layer includes 5 to 20 second sub-doping layers, each of which is provided with a first sub-negative electrode grid line, and each of the first sub-negative electrode grid lines is connected to a second PAD point.

8. The back contact solar cell according to claim 1, characterized in that: The first doping layer includes 5 to 20 first sub-doping layers, and the plurality of first sub-doping layers are distributed along a first direction; each of the first sub-doping layers is provided with a first sub-positive electrode grid line, and a first PAD point is provided every other first sub-positive electrode grid line; The second doping layer includes 5 to 40 second sub-doping layers, and the plurality of second sub-doping layers are distributed along the first direction. Each of the second sub-doping layers is provided with a first sub-negative gate line, and a second PAD point is provided every other first sub-negative gate line.

9. The back contact solar cell according to claim 1, characterized in that: The width of the first positive sub-gridline is greater than the widths of the other positive gridlines.

10. The back contact solar cell according to claim 1, characterized in that: It includes 1 to 12 groups of first PAD parts.

11. The back contact solar cell according to claim 1, characterized in that: Also includes: a first shunt gate line and a second shunt gate line, wherein the first shunt gate line is electrically connected to a plurality of the positive gate lines, and the second shunt gate line is electrically connected to a plurality of the negative gate lines; The first shunt gate line is electrically connected to the first PAD point, and the second shunt gate line is electrically connected to the second PAD point.

12. The back contact solar cell according to claim 3, characterized in that: Also includes: a first shunt gate line and a second shunt gate line, wherein the first shunt gate line electrically connects all positive gate lines located on the backlight surface, and the second shunt gate line electrically connects all negative gate lines located on the backlight surface; The first shunt gate line is electrically connected to the first PAD point, and the second shunt gate line is electrically connected to the second PAD point.

13. The back contact solar cell according to claim 11 or 12, characterized in that: The silicon substrate has a third edge and a fourth edge which are arranged opposite to each other in the second direction; The first shunt gate line is disposed close to the third edge, and the second shunt gate line is disposed close to the fourth edge.

14. The back contact solar cell according to claim 11 or 12, characterized in that: The positive grid line and the negative grid line are arranged on a side of the first shunt grid line facing the fourth edge; The positive gate line and the negative gate line are arranged on a side of the second shunt gate line facing the third edge.

15. The back contact solar cell according to claim 11 or 12, characterized in that: The distance between the first PAD point and the third edge is greater than the distance between the first shunt gate line and the third edge; The distance between the second PAD point and the fourth edge is greater than the distance between the second shunt gate line and the fourth edge.

16. The back contact solar cell according to claim 11 or 12, characterized in that: The distance between the first PAD point and the third edge is 3 mm to 5 mm; the distance between the second PAD point and the fourth edge is 3 mm to 5 mm; The distance between the first shunt gate line and the third edge is 0.2 mm to 2 mm, and the distance between the second shunt gate line and the fourth edge is 0.2 mm to 2 mm.

17. The back contact solar cell according to claim 11 or 12, characterized in that: The first PAD point is electrically connected to the first shunt gate line via a first connecting gate line; The second PAD point is electrically connected to the second shunt gate line through a second connecting gate line.

18. The back contact solar cell according to claim 11 or 12, characterized in that: The first connecting grid line is located on the extension line of the first positive sub-grid line to the third edge; The second connecting gate line is located on an extension line of the first negative sub-gate line toward the fourth edge.

19. The back contact solar cell according to claim 1, characterized in that: The first PAD point is disposed at the end of the first positive sub-grid line and is electrically connected to the first positive sub-grid line; The second PAD test point is disposed at an end of the first sub-negative gate line and is electrically connected to the first sub-negative gate line.

20. The back contact solar cell according to claim 1, characterized in that: The positive grid line further includes a second sub-positive grid line arranged close to the first sub-positive grid line; the first PAD point is connected to the first sub-positive grid line and at least two second sub-positive grid lines; The negative electrode grid line further includes a second sub-negative electrode grid line arranged close to the first sub-negative electrode grid line; the second PAD point is electrically connected to the first sub-negative electrode grid line and at least two second sub-negative electrode grid lines.

21. The back contact solar cell according to claim 20, characterized in that: A third negative gate line extending along the second direction is further provided on at least one side of the first connection gate line in the first direction, the third negative gate line being electrically connected to at least one negative gate line close to the first PAD point and being insulated from the first PAD point; The second connecting grid line is further provided with a third sub-positive grid line extending along the second direction on at least one side of the first direction. The third sub-positive grid line is electrically connected to at least one positive grid line close to the second PAD point and is insulated from the second PAD point.

22. The back contact solar cell according to claim 21, characterized in that The third negative sub-gate line is located on an extension line of the first negative sub-gate line connected to the second PAD point toward the third edge; and / or The third positive sub-grid line is located on an extension line of the first positive sub-grid line connected to the first PAD point toward the fourth edge.

23. The back contact solar cell according to claim 1, characterized in that: The first PAD point and the second PAD point are square, circular, triangular or irregular in shape.

24. The back contact solar cell according to claim 1, characterized in that: The first PAD point and the second PAD point are square in shape, and the width thereof is 0.1 mm to 1 mm.

25. The back contact solar cell according to claim 6, characterized in that: The second PAD portion includes a plurality of third PAD points and a plurality of fourth PAD points, and the plurality of third PAD points and the plurality of fourth PAD points are alternately arranged along the second direction.

26. The back contact solar cell according to claim 3, characterized in that: A second PAD portion is further provided in the first edge region and / or the second edge region; the second PAD portion includes a third PAD point and a fourth PAD point, the third PAD point is electrically connected to the positive electrode grid line, and the fourth PAD point is electrically connected to the negative electrode grid line; A first PAD point and a second PAD point located in the first edge region are arranged in a row with a third PAD point and a fourth PAD point located in the first edge region; The first PAD point and the second PAD point located in the second edge region are arranged in a row with the third PAD point and the fourth PAD point located in the second edge region.

27. A battery string, characterized in that: Comprising a back-contact solar cell as described in any one of claims 1 to 26.

28. A battery assembly, characterized in that: It comprises the back-contact solar cell according to any one of claims 1 to 26 or the cell string according to claim 27.

29. A photovoltaic system, characterized in that: Comprising a battery assembly as claimed in claim 28.

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