Back contact solar cell, cell string, assembly and photovoltaic system

Abstract

The utility model discloses a back contact solar cell, an assembly, a cell string 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 first positive electrode grid line, a first negative electrode grid line, a first test part and a second test part. The first doped layer comprises a first sub-doped layer, and the second doped layer comprises a second sub-doped layer; the second doping sub-layer and the first doping sub-layer form an electric leakage composite contact structure; the first positive electrode grid line is electrically connected with the first test part, and the first test part comprises a plurality of first test grid lines; the first cathode grid line is electrically connected with the second test part, and the second test part comprises a plurality of second test grid lines; the distance between the adjacent first / second test grid lines is smaller than the width of the test electrode. By implementing the embodiment, reverse current can be injected into the back contact solar cell through the first / second test part, and reverse breakdown voltage can be tested. By implementing the embodiment, the characterization of the hot spot resistance can be realized at the battery end.

Description

Technical Field

[0001] The utility model relates to the field of silicon solar cells, in particular to a back-contact solar cell, a cell string, 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 shaded, a voltage reverse bias will be generated. At this time, the shaded solar cell (slice) will become a load, consuming the power generated by the normal solar cell, thereby generating a large amount of heat, causing the temperature of the solar cell to be relatively high. This is what is generally called the hot spot effect. In order to solve the hot spot problem in the prior art, a diode is generally connected in reverse parallel at both ends of the string unit to reduce the current of the shaded solar cell and weaken the hot spot effect. However, this parallel diode will produce power loss. 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 manufacturing the solar cell, the doped layers of different polarities are partially contacted, thereby effectively reducing the reverse voltage at both ends of the shaded 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 solar cell end. Therefore, how to evaluate the hot spot effect at the solar cell end has become a technical problem that needs to be solved by those skilled in the art.

[0003] On the other hand, conventional hot spot effect testing generally involves shielding one or more solar cells (or sub-cells) in a solar cell module, exposing the remaining solar cells (or sub-cells) to light. After a certain period of time, the temperature of the shielded solar cell sub-cell is measured to characterize the hot spot effect. This is clearly not suitable for hot spot effect testing at the solar cell end. Utility Model Content

[0004] 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 the hot spot effect at the cell end.

[0005] In order to solve the above problems, the utility model discloses a back-contact solar cell, which includes:

[0006] A silicon substrate comprising a light-receiving surface and a backlight surface that are oppositely disposed;

[0007] A plurality of first doped layers and a plurality of second doped layers are provided on the backlight surface, the plurality of first doped layers and the plurality of second doped layers are alternately arranged along a first direction and extend along a second direction; the first doped layer includes at least one first sub-doped layer, the second doped layer includes at least one second sub-doped layer disposed adjacent to the first sub-doped layer; the second sub-doped layer and the first sub-doped layer form a leaky composite contact structure at a preset position;

[0008] at least one first positive gate line and at least one first negative gate line, wherein the first positive gate line is disposed above the first sub-doped layer and contacts the first sub-doped layer; and the first negative gate line is disposed above the second sub-doped layer and contacts the second sub-doped layer; and

[0009] a first test section and a second test section, wherein the first test section includes a plurality of first test gate lines, and the first test section is electrically connected to the first positive gate line; and the second test section includes a plurality of second test gate lines, and the second test section is electrically connected to the first negative gate line;

[0010] The distance between adjacent first test gate lines is smaller than the width of the test electrode, and the distance between adjacent second test gate lines is smaller than the width of the test electrode.

[0011] As an improvement to the above technical solution, the plurality of first test gate lines are distributed along the first direction with uniform or uneven spacing; and the first test gate lines extend along the second direction;

[0012] The plurality of second test gate lines are distributed along the first direction with uniform or non-uniform spacing; and the second test gate lines extend along the second direction.

[0013] As an improvement to the above technical solution, the silicon substrate has a first edge and a second edge that are oppositely arranged in the second direction;

[0014] At least one first test gate line is located on an extension line of the first positive gate line toward the first edge, and the first test gate line is in contact with the first sub-doped layer corresponding to the first positive gate line;

[0015] At least one second test gate line is located on an extension line of the first cathode gate line toward the second edge, and the second test gate line is in contact with the second sub-doped layer corresponding to the first cathode gate line.

[0016] As an improvement to the above technical solution, the plurality of first test gate lines are distributed along the second direction with uniform or uneven spacing; and the first test gate lines extend along the first direction;

[0017] The plurality of second test gate lines are distributed along the second direction with uniform or non-uniform spacing; and the second test gate lines extend along the first direction.

[0018] As an improvement of the above technical solution, the first testing portion and the second testing portion are not in contact with the first doping layer and the second doping layer.

[0019] As an improvement of the above technical solution, the first doping layer further includes a plurality of third sub-doping layers, and the second doping layer further includes a plurality of fourth sub-doping layers;

[0020] The back-contact solar cell also includes multiple second positive grid lines and multiple second negative grid lines, the second positive grid lines are arranged above the third sub-doped layer and in contact with the third sub-doped layer; the second negative grid lines are arranged above the fourth sub-doped layer and in contact with the fourth sub-doped layer.

[0021] As an improvement to the above technical solution, the silicon substrate has a first edge and a second edge that are oppositely arranged in the second direction;

[0022] The first testing portion is disposed close to the first edge, and the second testing portion is disposed close to the second edge.

[0023] As an improvement to the above technical solution, the first test section includes at least three first test gate lines uniformly distributed along the first direction; wherein, at least one first test gate line on both sides is connected to at least one second positive gate line located on both sides of the first positive gate line; and the middle first test gate line is connected to the first positive gate line.

[0024] As an improvement of the above technical solution, the second test section includes at least three second test gate lines evenly distributed along the first direction; wherein, at least one second test gate line on both sides is connected to at least one second negative gate line located on both sides of the first negative gate line; and the middle second test gate line is connected to the first negative gate line.

[0025] As an improvement to the above technical solution, the following is also included:

[0026] a first shunt gate line and a second shunt gate line, wherein the first shunt gate line extends along a first direction and is electrically connected to a plurality of the second positive gate lines and at least one first positive gate line;

[0027] The second shunt gate line extends along the second direction and is electrically connected to a plurality of second cathode gate lines and at least one first cathode gate line.

[0028] As an improvement to the above technical solution, the silicon substrate has a first edge and a second edge that are oppositely arranged in the second direction;

[0029] The first shunt gate line is arranged close to the first edge, and no other gate line is arranged between the first shunt gate line and the first edge;

[0030] The second shunt gate line is arranged close to the second edge, and no other gate line is arranged between the second shunt gate line and the second edge.

[0031] As an improvement to the above technical solution, the distance between the first testing portion and the first edge is greater than the distance between the first shunt gate line and the first edge;

[0032] A distance between the second testing portion and the second edge is greater than a distance between the second shunt gate line and the second edge.

[0033] As an improvement to the above technical solution, the distance between the first testing portion and the first edge is 3 mm to 8 mm; the distance between the second testing portion and the second edge is 3 mm to 8 mm;

[0034] The distance between the first shunt gate line and the first edge is 0.2 mm to 5 mm, and the distance between the second shunt gate line and the second edge is 0.2 mm to 5 mm.

[0035] As an improvement of the above technical solution, the first testing portion is electrically connected to the first shunt gate line via a first connecting gate line;

[0036] The second testing portion is electrically connected to the second shunt gate line through a second connecting gate line.

[0037] As an improvement of the above technical solution, a third negative gate line extending along the second direction is further provided on at least one side of the first connecting gate line in the first direction. The third negative gate line is connected to the second negative gate line and is insulated from the first test part.

[0038] As an improvement of the above technical solution, a third positive gate line extending along the second direction is further provided on at least one side of the second connecting gate line in the first direction. The third positive gate line is electrically connected to the second positive gate line and is insulated from the second testing part.

[0039] Correspondingly, the present invention also discloses a battery string, which includes the above-mentioned back-contact solar cell.

[0040] Correspondingly, the present invention also discloses a battery assembly, which includes the above-mentioned back-contact solar cell or the above-mentioned battery string.

[0041] Correspondingly, the present invention also discloses a photovoltaic system, which includes the above-mentioned battery assembly.

[0042] The implementation of this utility model has the following beneficial effects:

[0043] The back-contact solar cell in one embodiment of the present invention includes a silicon substrate, a first doped layer, a second doped layer, a first positive gate line, a first negative gate line, a first test section, and a second test section. The first doped layer includes a first sub-doped layer, and the second doped layer includes a second sub-doped layer; the second sub-doped layer and the first sub-doped layer form a leakage composite contact structure. The leakage composite contact structure can reduce the reverse voltage across the solar cell under peak current, reduce the heat generation power, reduce the probability of hot spot occurrence, and its peak temperature. Furthermore, in this embodiment, the first positive gate line is electrically connected to the first test section, and the first test section includes a plurality of first test gate lines; the first negative gate line is electrically connected to the second test section, and the second test section includes a plurality of second test gate lines; the distance between adjacent first / second test gate lines is less than the width of the test electrode. By implementing this embodiment, a reverse current can be injected into the back-contact solar cell through the first / second test section to test the reverse breakdown voltage. By implementing this embodiment, the characterization of anti-hot spot performance can be achieved at the cell end. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the back structure of a back-contact solar cell in one embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the back structure of a back-contact solar cell in another embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the distribution structure of the first doping layer, the second doping layer, and the leakage composite contact structure in one embodiment of the present utility model;

[0047] In the figure, 1 is a silicon substrate, 11 is a first edge, 12 is a second edge, 21 is a first doped layer, 221 is a first sub-doped layer, 212 is a third sub-doped layer, 22 is a second doped layer, 221 is a second sub-doped layer, 222 is a fourth sub-doped layer, 3 is a leakage composite contact structure, 41 is a first positive gate line, 42 is a first negative gate line, 43 is a second positive gate line, 44 is a second negative gate line, 45 is a third positive gate line, 46 is a third negative gate line, 51 is a first test part, 511 is a first test gate line, 512 is a third connecting gate line, 52 is a second test part, 521 is a second test gate line, 522 is a fourth connecting gate line, 61 is a first shunt gate line, 62 is a second shunt gate line, 71 is a first connecting gate line, and 72 is a second connecting gate line. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below with reference to 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 are not to be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are merely used to explain the present application and are not intended to limit the present application.

[0049] In the description of this 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. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0051] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0052] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0053] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art will appreciate the application of other processes and / or the use scenarios of other materials.

[0054] See also Figure 1 This embodiment provides a back-contact solar cell, comprising a silicon substrate 1, a plurality of first doped layers 21, a plurality of second doped layers 22, at least one first positive gate line 41, at least one first negative gate line 42, at least one first test portion 51, and at least one second test portion 52. The silicon substrate 1 comprises a light-receiving surface and a backlight surface oppositely disposed, and the first doped layers 21, the second doped layers 22, the first positive gate line 41, the second positive gate line 43, the first test portion 51, and the second test portion 52 are all disposed on the backlight surface. Multiple first doping layers 21 and multiple second doping layers 22 are alternately arranged along the first direction and extend along the second direction; 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 arranged adjacent to the first sub-doping layer 211; the second sub-doping layer 221 and the first sub-doping layer 211 form a leakage composite contact structure 3 at a preset position; based on the leakage composite contact structure 3, the reverse voltage at both ends of the back-contact solar cell under peak current can be reduced, the heat generation power can be reduced, and the probability of hot spots occurring can be reduced.

[0055] The silicon substrate 1 may be, but is not limited to, P-type monocrystalline silicon, N-type monocrystalline silicon, P-type polycrystalline silicon, or N-type polycrystalline silicon. N-type monocrystalline silicon is preferred. The silicon substrate 1 may be, but is not limited to, a circular, regular hexagonal, octagonal, or rectangular shape. Preferably, the silicon substrate 1 is rectangular and has chamfered corners. When the silicon substrate 1 is rectangular, it has a first edge 11 and a second edge 12 disposed opposite each other in a first direction.

[0056] The first positive gate line 41 is disposed above and in contact with the first sub-doped layer 211, and the first test portion 51 is electrically connected to the first positive gate line 41. The first negative gate line 42 is disposed above and in contact with the second sub-doped layer 221. The second test portion 52 is electrically connected to the first negative gate line 42.

[0057] Specifically, the first test section 51 includes multiple first test grid lines 511, and the second test section 52 includes multiple second test grid lines 521; and the distance between adjacent first test grid lines 511 is less than the width of the test electrode, and the distance between adjacent second test grid lines 521 is less than the width of the test electrode, so as to inject reverse current into the back-contact solar cell through the first test grid lines 511 and the second test grid lines 521, and flow through the leakage composite contact structure 3 to test the reverse breakdown voltage of the back-contact solar cell. Among them, the test electrode refers to the electrode used for injecting current in the test equipment. Based on the technical solution of this embodiment, the reverse breakdown voltage of the back-contact solar cell provided with the leakage composite contact structure 3 can be measured, providing a good basis for characterizing the hot spot effect at the cell end. It should be noted that conventional hot spot testing is generally performed at the component end, that is, any one or more solar cell slices in the solar cell module are blocked, and the 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 further characterize the hot spot effect. Existing technologies struggle to accurately quantify the hot spot effect at the cell end. However, this embodiment, after introducing the leaky composite contact structure 3, measures its reverse breakdown voltage, allowing for quantitative characterization of the hot spot effect through reverse breakdown voltage, providing a sound foundation for controlling the hot spot effect in components. It should be noted that the first test section 51 and the second test section 52 in this embodiment can be used not only to measure reverse breakdown voltage, but also to test other parameters of conventional back-contact solar cells, such as EL, open-circuit voltage, short-circuit current, and conversion efficiency.

[0058] Among them, the first test gate line 511 in the first test section 51 and the second test gate line 521 in the second test section 52 can extend in any direction, for example, they can extend in the horizontal direction (second direction), or in the vertical direction (first direction), or in a direction that forms any angle with the horizontal direction / vertical direction, but are not limited thereto.

[0059] Preferably, see Figure 1In one embodiment, a plurality of first test gate lines 511 are distributed along the first direction at uniform or uneven spacing; and the first test gate lines 511 extend along the second direction; a plurality of second test gate lines 521 are distributed along the first direction at uniform or uneven spacing; and the second test gate lines 521 extend along the second direction. Furthermore, at least one first test gate line 511 is located on the extension line of the first positive gate line 41 toward the first edge 11, and the first test gate line 511 is in contact with the first sub-doped layer corresponding to the first positive gate line 11; at least one second test gate line 521 is located on the extension line of the first negative gate line 42 toward the second edge 12, and the second test gate line 521 is in contact with the second sub-doped layer 221 corresponding to the first negative gate line 42. Based on this embodiment, not only can accurate measurement be achieved, but also the carrier collection efficiency can be improved, thereby improving the conversion efficiency of the back-contact solar cell.

[0060] See also Figure 2 In another embodiment, multiple first test gate lines 511 are evenly or unevenly spaced along the second direction, and the first test gate lines 511 extend along the first direction. Multiple second test gate lines 521 are evenly or unevenly spaced along the second direction, and the second test gate lines 521 extend along the first direction. Furthermore, based on this embodiment, the first test portion 51 and the second test portion 52 do not contact the first doped layer 21 and the second doped layer 22 to prevent short circuits.

[0061] Specifically, the leakage composite contact structure 3 can be obtained by extending the first sub-doped layer 211 / the second sub-doped layer 221 to the second sub-doped layer 221 / the first sub-doped layer 211 in a predetermined area, or by stacking the first sub-doped layer 211 and the second sub-doped layer 221 on each other in a predetermined area, but is not limited thereto. Preferably, see Figure 2 In one embodiment, the second sub-doping layer 221 disposed on one or both sides of the first sub-doping layer 211 extends above the first doping layer 21 at multiple preset positions to partially cover the first sub-doping layer 211, forming a leakage composite contact structure 3. Each first sub-doping layer 211 is provided with multiple leakage composite contact structures 3 along the second direction. Preferably, the multiple leakage composite contact structures 3 located on the same first sub-doping layer 211 are uniformly distributed along the second direction. When the above-mentioned leakage composite contact structure 3 is adopted, the second sub-doping layer 221 extending above the first sub-doping layer 211 partially covers the first sub-doping layer 211 in the first direction to prevent the first positive gate line 41 disposed above the first sub-doping layer 211 from contacting the second sub-doping layer 221 and causing leakage.

[0062] Specifically, the number of the first sub-doped layers 211 can be determined according to the magnitude of the leakage current, and can be 1, 2, 5, 10 or 15, but is not limited thereto. Preferably, the number of the first sub-doped layers 211 is 10 to 25.

[0063] In one embodiment, the first doping layer 21 further includes a plurality of third sub-doping layers 212, and the second doping layer 22 further includes a plurality of fourth sub-doping layers 222. The third sub-doping layers 212 and the fourth sub-doping layers 222 are alternately arranged along the first direction. The third sub-doping layers 212 and the fourth sub-doping layers 222 are insulated from each other. Specifically, the insulation between the third sub-doping layers 212 and the fourth sub-doping layers 222 can be achieved by providing a gap between the third sub-doping layers 212 and the fourth sub-doping layers 222, but is not limited thereto.

[0064] Correspondingly, a second positive gridline 43 is provided above the third sub-doped layer 212, and the second positive gridline 43 contacts the third sub-doped layer 212. A second negative gridline 44 is provided above the fourth sub-doped layer 222, and the second negative gridline 44 contacts the fourth sub-doped layer 222. By designing multiple second positive gridlines 43 and second negative gridlines 44, the amount of carrier collection can be increased, thereby improving the conversion efficiency of the back-contact solar cell.

[0065] Specifically, in one embodiment, the first test section 51 is disposed near the first edge 11, and the second test section 52 is disposed near the second edge 12. It should be noted that the first positive grid line 41, the second positive grid line 43, the first negative grid line 42, and the second negative grid line 44 all have line resistance. After reverse current is passed, a voltage divider will exist on these grid lines. In addition, contact resistance exists between the first positive grid line 41 and the first sub-doped layer 211, the second positive grid line 43 and the third sub-doped layer 212, the first negative grid line 42 and the second sub-doped layer 221, and the second negative grid line 44 and the fourth sub-doped layer 222, which will also produce a voltage divider. Therefore, in order to more accurately characterize the reverse breakdown voltage of the back-contact solar cell, it is necessary to consider the grid line resistance voltage divider and the contact resistance voltage divider. In this embodiment, the first test section 51 and the second test section 52 are arranged close to the edge of the silicon wafer, so that the reverse current flows in the second direction through the longer first positive gate line 41 / second positive gate line 43 and first negative gate line 42 / second negative gate line 44, which can better characterize the effects of the gate line resistance voltage division and the contact resistance voltage division on the reverse breakdown voltage.

[0066] Specifically, the number of first test gate lines 511 in the first test section 51 is 2 to 10, exemplarily 3, 5, 7 or 9, but not limited thereto. The multiple first test gate lines 511 are evenly spaced or unevenly spaced in the first direction. Preferably, in one embodiment, the first test section 51 includes at least 3 first test gate lines 511 evenly spaced along the first direction, and at least one first test gate line 511 on both sides is connected to at least one second positive gate line 43 located on both sides of the first positive gate line 41, and the middle first test gate line 511 is connected to the first positive gate line 41. Based on this embodiment, the reverse current injected by the first test section 51 can flow directly through at least one second positive gate line 43 and the first positive gate line 41 via the first test gate line 511, thereby better characterizing the influence of the gate line resistance voltage divider and the contact resistance voltage divider on the reverse breakdown voltage. More preferably, in one embodiment, the first test section 51 includes five first test gate lines 511 uniformly distributed along the first direction, wherein the two first test gate lines 511 on both sides are respectively connected to the two second positive gate lines 43 located on both sides of the first positive gate line 41, and the middle first test gate line 511 is connected to the first positive gate line 41.

[0067] Specifically, the first test gate line 511 may be linear or curved, but is not limited thereto. Preferably, in one embodiment, the first test gate line 511 is linear and extends along the second direction. A plurality of first test gate lines 511 are connected by a third connection gate line 512, and the third connection gate line 512 extends along the second direction.

[0068] Specifically, the number of second test gate lines 521 in the second test section 52 is 2 to 10, exemplarily 3, 5, 7 or 9, but not limited thereto. The plurality of second test gate lines 521 are evenly spaced or unevenly spaced in the first direction. Preferably, in one embodiment, the second test section 52 includes at least 3 second test gate lines 521 evenly spaced along the first direction, and at least one second test gate line 521 on both sides is connected to at least one second negative gate line 44 located on both sides of the first negative gate line 42, and the middle second test gate line 521 is connected to the first negative gate line 42. Based on this embodiment, the reverse current flows through at least one second negative gate line 44 and the first negative gate line 42, thereby better characterizing the influence of the gate line line resistance voltage divider and the contact resistance voltage divider on the reverse breakdown voltage. More preferably, in one embodiment, the second test section 52 includes five second test gate lines 521 uniformly distributed along the first direction, wherein the two second test gate lines 521 on both sides are respectively connected to the two second negative gate lines 44 located on both sides of the first negative gate line 42, and the middle second test gate line 521 is connected to the first negative gate line 42.

[0069] Specifically, the second test gate lines 521 may be linear or curved, but are not limited thereto. Preferably, in one embodiment, the second test gate lines 521 are linear and extend along the second direction. A plurality of second test gate lines 521 are connected by fourth connection gate lines 522, and the fourth connection gate lines 522 extend along the second direction.

[0070] Preferably, in some embodiments, the back-contact solar cell further includes a first shunt grid line 61 and a second shunt grid line 62, wherein the first shunt grid line 61 extends along the first direction and is electrically connected to a plurality of second positive grid lines 43 and at least one first positive grid line 41. The second shunt grid line 62 extends along the first direction and is electrically connected to a plurality of second negative grid lines 44 and at least one first negative grid line 42. Based on the above embodiment, the reverse current can be shunted to a plurality of first positive grid lines 41 and second positive grid lines 43 via the first shunt grid line 61, and then flow through a plurality of first negative grid lines 42 and second negative grid lines 44 before being collected via the second shunt grid line 62, thereby achieving a better effect of characterizing the influence of grid line resistance voltage division and contact resistance voltage division on the accuracy of the reverse breakdown voltage test.

[0071] Specifically, the first shunt gate line 61 and the second shunt gate line 62 can be arranged in the middle of the backlight surface, or close to the edge, but are not limited thereto. Preferably, in one embodiment, the first shunt gate line 61 is arranged close to the first edge 11, and the second shunt gate line 62 is arranged close to the second edge 12. Based on this embodiment, other gate line structures can be simplified. It should be noted that since the first shunt gate line 61 and the second shunt gate line 62 extend along the first direction and have different polarities, if they are arranged in the middle of the backlight surface of the silicon wafer, it is necessary to introduce an insulating structure into the first positive gate line 41, the second positive gate line 43, the first negative gate line 42, and the second negative gate line 44, which complicates the gate line structure, reduces carrier collection, and affects conversion efficiency.

[0072] Specifically, when the first test section 51 and the first shunt gate line 61 are both positioned near the first edge 11, and the second test section 52 and the second shunt gate line 62 are positioned near the second edge 12, the distance between the first test section 51 and the first edge 11 is greater than the distance between the first shunt gate line 61 and the first edge 11; and the distance between the second test section 52 and the second edge 12 is greater than the distance between the second shunt gate line 62 and the second edge 12. Exemplarily, the distance between the first test section 51 and the first edge 11 can be 3 mm to 8 mm, the distance between the second test section 52 and the second edge 12 can be 3 mm to 8 mm, the distance between the first shunt gate line 61 and the first edge 11 can be 0.2 mm to 5 mm, and the distance between the second shunt gate line 62 and the second edge 12 can be 0.2 mm to 5 mm, but the present invention is not limited thereto. It should be noted that, in this embodiment, the distance between the first test section 51 and the first edge 11 refers to the distance between the end of the first test gate line 511 near the first edge 11 and the first edge 11. The distance between the second test portion 52 and the second edge 12 refers to the distance between the end of the second test gate line 512 close to the second edge 12 and the second edge 12.

[0073] Specifically, in the above embodiment, the first test section 51 can be directly connected to the first shunt gate line 61, or connected through the first connecting gate line 71, but is not limited thereto. The second test section 52 can be directly connected to the second shunt gate line 62, or connected through the second connecting gate line 72, but is not limited thereto. When connected through the first connecting gate line 71 / the second connecting gate line 72, a spacing area can be left between the first test section 51 / the second test section 52 and the first shunt gate line 61 / the second shunt gate line 62. Gate lines of different polarities can be set in this spacing area to collect carriers of different polarities, thereby improving conversion efficiency.

[0074] Preferably, in one embodiment, a third negative gate line 46 extending along the second direction is further provided on at least one side of the first connecting gate line 71 in the first direction. The third negative gate line 46 is electrically connected to the second negative gate line 44 and is insulated from the first test portion 51, thereby collecting carriers in the gap area between the first shunt gate line 61 and the first test portion 51 through the third negative gate line 46.

[0075] Correspondingly, a third positive grid line 45 extending along the second direction is further provided on at least one side of the second connecting line in the first direction. The third positive grid line 45 is electrically connected to the second positive grid line 43 and is insulated from the second test portion 52 so as to collect carriers in the spacing area between the second shunt grid line 62 and the second test portion 52 through the third positive grid line 45.

[0076] Accordingly, this embodiment also discloses a battery comprising the aforementioned back-contact solar cell. The cell string may be formed by shingling or welding multiple back-contact solar cells or their resulting slices, but is not limited thereto. Accordingly, to connect the multiple back-contact solar cells, the cell string assembly may also include, but is not limited to, soldering tape, insulating adhesive, adhesive, conductive adhesive, and the like.

[0077] Accordingly, this embodiment also discloses a battery assembly comprising the aforementioned back-contact solar cell or the aforementioned battery string. Preferably, in one embodiment, the battery assembly is composed of a plurality of the aforementioned battery strings, exemplarily comprising two, four, or six strings, but not limited thereto. Accordingly, to form connections between the battery strings, the battery assembly also requires, but is not limited to, components such as insulating adhesive, busbars, junction boxes, frames, backsheets, adhesive films, and glass.

[0078] Correspondingly, this embodiment also discloses a photovoltaic system, which includes the above-mentioned battery assembly. In this embodiment, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array can be an array combination of multiple battery assemblies. For example, multiple battery assemblies can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter to be converted into the alternating current required by the mains power grid and then connected to the mains power network to achieve solar power supply.

[0079] Throughout this specification, reference to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, the illustrative use of the above terms does not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0080] In addition, the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

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 oppositely disposed; A plurality of first doped layers and a plurality of second doped layers are provided on the backlight surface, the plurality of first doped layers and the plurality of second doped layers are alternately arranged along a first direction and extend along a second direction; the first doped layer includes at least one first sub-doped layer, the second doped layer includes at least one second sub-doped layer disposed adjacent to the first sub-doped layer; the second sub-doped layer and the first sub-doped layer form a leaky composite contact structure at a preset position; at least one first positive gate line and at least one first negative gate line, wherein the first positive gate line is disposed above the first sub-doped layer and contacts the first sub-doped layer; and the first negative gate line is disposed above the second sub-doped layer and contacts the second sub-doped layer; and a first test section and a second test section, wherein the first test section includes a plurality of first test gate lines, and the first test section is electrically connected to the first positive gate line; and the second test section includes a plurality of second test gate lines, and the second test section is electrically connected to the first negative gate line; The distance between adjacent first test gate lines is smaller than the width of the test electrode, and the distance between adjacent second test gate lines is smaller than the width of the test electrode.

2. The back contact solar cell according to claim 1, wherein The plurality of first test gate lines are distributed along the first direction with uniform or uneven spacing; and the first test gate lines extend along the second direction; The plurality of second test gate lines are distributed along the first direction with uniform or non-uniform spacing; and the second test gate lines extend along the second direction.

3. The back contact solar cell according to claim 2, wherein: The silicon substrate has a first edge and a second edge opposite to each other in the second direction; At least one first test gate line is located on an extension line of the first positive gate line toward the first edge, and the first test gate line is in contact with the first sub-doped layer corresponding to the first positive gate line; At least one second test gate line is located on an extension line of the first cathode gate line toward the second edge, and the second test gate line is in contact with the second sub-doped layer corresponding to the first cathode gate line.

4. The back contact solar cell according to claim 1, wherein The plurality of first test gate lines are distributed along the second direction with uniform or uneven spacing; and the first test gate lines extend along the first direction; The plurality of second test gate lines are distributed along the second direction with uniform or non-uniform spacing; and the second test gate lines extend along the first direction.

5. The back contact solar cell according to claim 4, wherein: The first testing portion and the second testing portion are not in contact with the first doping layer and the second doping layer.

6. The back contact solar cell according to claim 1, wherein The first doping layer further includes a plurality of third sub-doping layers, and the second doping layer further includes a plurality of fourth sub-doping layers; The back-contact solar cell also includes multiple second positive grid lines and multiple second negative grid lines, the second positive grid lines are arranged above the third sub-doped layer and in contact with the third sub-doped layer; the second negative grid lines are arranged above the fourth sub-doped layer and in contact with the fourth sub-doped layer.

7. The back contact solar cell according to claim 1, wherein The silicon substrate has a first edge and a second edge opposite to each other in the second direction; The first testing portion is disposed close to the first edge, and the second testing portion is disposed close to the second edge.

8. The back contact solar cell according to claim 2, wherein: The first test section includes at least three first test gate lines uniformly distributed along a first direction; wherein, at least one first test gate line on both sides is connected to at least one second positive gate line located on both sides of the first positive gate line; and the middle first test gate line is connected to the first positive gate line.

9. The back contact solar cell according to claim 2, wherein: The second test section includes at least three second test gate lines evenly distributed along the first direction; wherein, at least one second test gate line on both sides is connected to at least one second negative gate line located on both sides of the first negative gate line; and the middle second test gate line is connected to the first negative gate line.

10. The back contact solar cell according to claim 6, wherein: Also includes: a first shunt gate line and a second shunt gate line, wherein the first shunt gate line extends along a first direction and is electrically connected to a plurality of the second positive gate lines and at least one first positive gate line; The second shunt gate line extends along the second direction and is electrically connected to a plurality of second cathode gate lines and at least one first cathode gate line.

11. The back contact solar cell according to claim 10, wherein: The silicon substrate has a first edge and a second edge opposite to each other in the second direction; The first shunt gate line is disposed close to the first edge, and the second shunt gate line is disposed close to the second edge.

12. The back contact solar cell according to claim 11, wherein: The distance between the first testing portion and the first edge is greater than the distance between the first shunt gate line and the first edge; A distance between the second testing portion and the second edge is greater than a distance between the second shunt gate line and the second edge.

13. The back contact solar cell according to claim 11, wherein: The distance between the first testing portion and the first edge is 3 mm to 8 mm; the distance between the second testing portion and the second edge is 3 mm to 8 mm; The distance between the first shunt gate line and the first edge is 0.2 mm to 5 mm, and the distance between the second shunt gate line and the second edge is 0.2 mm to 5 mm.

14. The back contact solar cell according to claim 10, wherein: The first test portion is electrically connected to the first shunt gate line via a first connecting gate line; The second testing portion is electrically connected to the second shunt gate line through a second connecting gate line.

15. The back contact solar cell according to claim 14, wherein: A third negative gate line extending along the second direction is further provided on at least one side of the first connecting gate line in the first direction. The third negative gate line is connected to the second negative gate line and is insulated from the first testing portion.

16. The back contact solar cell according to claim 14, wherein: A third positive gate line extending along the second direction is further provided on at least one side of the second connection gate line in the first direction. The third positive gate line is electrically connected to the second positive gate line and is insulated from the second test portion.

17. A battery string, characterized in that: The invention comprises a back-contact solar cell according to any one of claims 1 to 16.

18. A battery assembly, characterized in that: It comprises the back-contact solar cell according to any one of claims 1 to 16 or the cell string according to claim 17.

19. A photovoltaic system, characterized in that: Comprising the battery assembly as claimed in claim 18.

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