Back contact solar cell, cell module and photovoltaic system

Abstract

The invention is suitable for the technical field of solar cells, and provides a back contact solar cell, a cell assembly and a photovoltaic system. The first fine grids and the second fine grids are arranged on the back surface of the silicon substrate; the at least one group of first bonding pads are arranged on the back surface of the silicon substrate, and the first bonding pads are electrically connected with the first fine grids; the at least one group of second bonding pads are arranged on the back surface of the silicon substrate and are electrically connected with the second fine grids; the first test structure comprises two third bonding pads which are arranged at intervals in the first direction, and the third bonding pads are electrically connected with the first fine grids; the third bonding pad and the first bonding pad are the same in size; the second testing structure comprises two fourth bonding pads which are adjacently arranged in the first direction, the fourth bonding pads are electrically connected with the second fine grids, and the fourth bonding pads and the second bonding pads are the same in size. According to the back contact solar cell provided by the invention, the carrier collection effect of the fine grid can be improved, and the printing cost of the back contact solar cell can be reduced.

Description

Technical Field

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

[0002] Solar cells, also known as photovoltaic cells, are devices that use the photovoltaic effect to directly convert light energy into direct current. Among them, the back-contact solar cell has both positive and negative electrodes designed on the back of the cell. Compared with double-sided solar cells, the front surface of the back-contact solar cell completely avoids the shading of the metal grid line, eliminating the optical loss caused by the shading of the metal grid line, which can greatly improve the cell conversion efficiency.

[0003] In the related art, the back of the back contact solar cell is usually provided with a connection pad for welding the welding strip to realize the series connection between the solar cells; at the same time, since the back contact solar cell needs to be tested for current and voltage before leaving the factory, at least two test structures are usually required to be provided on the back of the back contact solar cell. Since the current test probe and the voltage test probe of the test equipment need to be in contact with the test structure at the same time when the back contact solar cell is tested for performance, the size of the test structure of the back contact solar cell is required to be set to be larger. Generally, each test structure of the back contact solar cell is usually a single large-sized test pad, and the size of the test pad is larger than the size of the connection pad, especially the length of a single test pad is usually more than three times the length of the connection pad. Due to the large size of the test pad, the width of the discontinuity of the opposite polarity of the test pad at the test pad is large, resulting in poor fine grid carrier collection effect at the test pad position, thereby affecting the battery efficiency; moreover, the large size of the test pad will result in more slurry printing of the test pad, resulting in high printing cost of the test pad, thereby making the printing cost of the back contact solar cell high. Summary of the invention

[0004] The present invention provides a back-contact solar cell, aiming to solve the problems of poor fine-grid carrier collection effect and high printing cost in the back-contact solar cell of the prior art.

[0005] The present invention is implemented by providing a back contact solar cell, comprising:

[0006] Silicon substrate;

[0007] A plurality of first fine gates and a plurality of second fine gates are disposed on the back side of the silicon substrate, the plurality of first fine gates and the plurality of second fine gates are alternately arranged in sequence along a first direction, the first fine gates and the second fine gates both extend along the second direction, and the second direction intersects with the first direction;

[0008] At least one set of first pads disposed on the back surface of the silicon substrate, each set of the first pads including at least one first pad, the first pad being electrically connected to the first fine grid;

[0009] At least one set of second pads disposed on the back surface of the silicon substrate, each set of the second pads including at least one second pad, the second pad being electrically connected to the second fine grid;

[0010] At least one first test structure disposed on the back surface of the silicon substrate, the first test structure including two third pads spaced apart along the first direction and electrically connected to each other, the third pad being electrically connected to the first fine grid, the third pad being spaced apart from the second fine grid; the third pad has the same size as the first pad along the first direction, the third pad has the same size as the first pad along the second direction, the distance between two adjacent first pads along the first direction is greater than the distance between the two third pads of the first test structure or the distance between the third pad and the adjacent first pad in the first direction is greater than the distance between the two third pads of the first test structure; and

[0011] At least one second test structure disposed on the back surface of the silicon substrate, the second test structure including two fourth pads adjacent to each other along the first direction and electrically connected to each other, the fourth pad being electrically connected to the second fine grid, the fourth pad being spaced apart from the first fine grid, the fourth pad has the same size as the second pad along the first direction, the fourth pad has the same size as the second pad along the second direction, the distance between two adjacent second pads along the first direction is greater than the distance between the two fourth pads of the second test structure or the distance between the fourth pad and the adjacent second pad in the first direction is greater than the distance between the two fourth pads of the second test structure.

[0012] Preferably, the first pad, the second pad, the third pad, and the fourth pad have the same shape and size.

[0013] Preferably, the distance between the two third pads of the first test structure is L2, the distance between two adjacent second fine grids is L5, L2 is greater than or equal to L5, and L2 is less than or equal to 3L5.

[0014] Preferably, the distance between the two fourth pads of the second test structure is L4, the distance between two adjacent first fine grids is L6, L4 is greater than or equal to L6, and L4 is less than or equal to 3L6.

[0015] Preferably, each group of the first pads includes a plurality of the first pads arranged at intervals along the first direction, and the ratio of the distance between two adjacent first pads in the first direction to the distance between two third pads of the first test structure is 8 to 15; and / or, each group of the second pads includes a plurality of the second pads arranged at intervals along the first direction, and the ratio of the distance between two adjacent second pads in the first direction to the distance between two fourth pads of the second test structure is 8 to 15.

[0016] Preferably, the ratio of the distance between two adjacent first pads in the first direction to the distance between two third pads of the first test structure is 9 to 10; and / or, the ratio of the distance between two adjacent second pads in the first direction to the distance between two fourth pads of the second test structure is 9 to 10.

[0017] Preferably, the distance between two third pads of the first test structure is greater than the length of the third pad; and / or, the distance between two fourth pads of the second test structure is greater than the length of the fourth pad.

[0018] Preferably, the distance between two third pads of the first test structure is less than or equal to twice the length of the third pad; the distance between two fourth pads of the second test structure is less than or equal to twice the length of the fourth pad.

[0019] Preferably, the first test structure includes a first connecting portion connecting two third pads, the width of the first connecting portion is less than the width of the third pad, the second fine grid forms a first break at the position of the first connecting portion, and the second fine grid is spaced from the first connecting portion through the first break;

[0020] The second fine grid forms a second break at the position of the third pad, the second fine grid is spaced from the third pad through the second break, and the width of the first break is less than the width of the second break.

[0021] Preferably, the second test structure includes a second connecting portion connecting two fourth pads, the width of the second connecting portion is less than the width of the fourth pad, the first fine grid forms a third break at the position of the second connecting portion, and the first fine grid is spaced from the second connecting portion through the third break;

[0022] The first fine grid forms a fourth break at the position of the fourth pad, the first fine grid is spaced from the fourth pad through the fourth break, and the width of the third break is less than the width of the fourth break.

[0023] Preferably, the width of the first pad is 3 to 5 times the width of the first connecting portion; and / or, the width of the second pad is 3 to 5 times the width of the second connecting portion.

[0024] Preferably, it includes:

[0025] A plurality of first main grids disposed on the back surface of the silicon substrate, the first main grids extending along the first direction and connected to the first fine grids, the first main grids being spaced apart from the second fine grids, a plurality of the first pads being provided on the first main grids at intervals along the first direction, and the first test structure being disposed on the first main grids; and

[0026] A plurality of second main grids disposed on the back surface of the silicon substrate, the plurality of second main grids and the plurality of first main grids being alternately arranged in sequence along the second direction, the second main grids extending along the first direction and connected to the second fine grids, the second main grids being spaced apart from the first fine grids, a plurality of the second pads being provided on the second main grids at intervals along the first direction, and the second test structure being disposed on the second main grids.

[0027] The present invention also provides a battery module, including the above-mentioned back-contact solar cell.

[0028] The present invention also provides a photovoltaic system, including the above-mentioned battery module.

[0029] A back-contact solar cell provided by the present invention sets the first test structure to include two third pads spaced along a first direction. The third pads have the same size as the first pads, and the distance between two adjacent first pads along the first direction is greater than the distance between the two third pads of the first test structure or the distance between a third pad and an adjacent first pad in the first direction is greater than the distance between the two third pads of the first test structure. Since the first test structure is set as two spaced third pads and there is no pad structure between the two third pads, the width design of the break of the second fine grid in the area between the two third pads can be reduced, thereby increasing the total length of the second fine grid, improving the carrier collection effect of the second fine grid, and further improving the cell efficiency. At the same time, the second test structure is set to include two fourth pads spaced along the first direction. The fourth pads have the same size as the second pads, and the distance between two adjacent second pads along the first direction is greater than the distance between the two fourth pads of the second test structure or the distance between a fourth pad and an adjacent second pad in the first direction is greater than the distance between the two fourth pads of the second test structure. Since there is no pad structure between the two fourth pads, the width design of the break of the first fine grid in the area between the two fourth pads can be reduced, thereby increasing the total length of the first fine grid, improving the carrier collection effect of the first fine grid, and further improving the cell efficiency. Moreover, the length of a single test pad in a back-contact solar cell in the related art is usually more than three times the length of the connection pad, while the sum of the lengths of the two third pads of the first test structure of the present invention is only twice the length of the first pad, and the sum of the lengths of the two fourth pads of the second test structure is only twice the length of the second pad. This can reduce the amount of pad paste used in the first test structure and the second test structure, lower the printing cost of the first test structure and the second test structure, thereby reducing the printing cost of the back-contact solar cell, and further reducing the production cost of the back-contact solar cell. In addition, since the third pads have the same size as the first pads and the fourth pads have the same size as the second pads, it is convenient for the pad design and printing preparation of the back-contact solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a plan view of a back-contact solar cell provided by an embodiment of the present invention;

[0031] Figure 2 is a partial view of a back-contact solar cell provided by an embodiment of the present invention;

[0032] Figure 3 is an enlarged view of the position of the first test structure of a back-contact solar cell provided by an embodiment of the present invention;

[0033] Figure 4 is an enlarged view of the position of the second test structure of a back-contact solar cell provided by an embodiment of the present invention. Detailed implementation mode

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "back", "front", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention 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 thus should not be construed as a limitation to the present invention.

[0036] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include indirect contact between the first and second features through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0037] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use scenarios of other materials.

[0038] Please refer to Figures 1-4 , an embodiment of the present invention provides a back-contact solar cell, including:

[0039] A silicon substrate 1;

[0040] A plurality of first fine grids 2 and a plurality of second fine grids 3 are provided on the back surface 11 of the silicon substrate 1. The plurality of first fine grids 2 and the plurality of second fine grids 3 are alternately arranged at intervals in sequence along the first direction Y. Both the first fine grid 2 and the second fine grid 3 extend along the second direction X, and the second direction X intersects with the first direction Y.

[0041] At least one group of first pads 4 is provided on the back surface 11 of the silicon substrate 1. Each group of first pads 4 includes at least one first pad 4, and the first pad 4 is electrically connected to the first fine grid 2.

[0042] At least one group of second pads 5 is provided on the back surface 11 of the silicon substrate 1. Each group of second pads 5 includes at least one second pad 5, and the second pad 5 is electrically connected to the second fine grid 3.

[0043] At least one first test structure 6 is provided on the back surface 11 of the silicon substrate 1. The first test structure 6 includes two third pads 61 that are arranged at intervals along the first direction Y and are electrically connected to each other. The third pad 61 is electrically connected to the first fine grid 2, and the third pad 61 is spaced apart from the second fine grid 3. The third pad 61 has the same dimension as the first pad 4 along the first direction Y, and the third pad 61 has the same dimension as the first pad 4 along the second direction X. The distance L1 between two adjacent first pads 4 along the first direction Y is greater than the distance L2 between the two third pads 61 of the first test structure 6, or the distance L11 between the third pad 61 and the adjacent first pad 4 in the first direction Y is greater than the distance L2 between the two third pads 61 of the first test structure 6; and

[0044] At least one second test structure 7 is provided on the back surface 11 of the silicon substrate 1. The second test structure 7 includes two fourth pads 71 that are adjacent to each other and are electrically connected to each other along the first direction Y. The fourth pad 71 is electrically connected to the second fine grid 3, and the fourth pad 71 is spaced apart from the first fine grid 2. The fourth pad 71 has the same dimension as the second pad 5 along the first direction Y, and the fourth pad 71 has the same dimension as the second pad 5 along the second direction X. The distance L3 between two adjacent second pads 5 along the first direction Y is greater than the distance L4 between the two fourth pads 71 of the second test structure 7, or the distance L12 between the fourth pad 71 and the adjacent second pad 5 in the first direction Y is greater than the distance L4 between the two fourth pads 71 of the second test structure 7.

[0045] In an embodiment of the present invention, a plurality of first fine grids 2 and a plurality of second fine grids 3 are arranged on the back surface 11 of the silicon substrate 1 for collecting and transporting photo-generated carriers, so as to realize the electric energy conversion of the back-contact battery. Among them, the first fine grid 2 is one of the positive electrode or the negative electrode, and the second fine grid 3 is the other of the positive electrode or the negative electrode. Among them, the back-contact solar cell can be a main-gridless back-contact solar cell, that is, no main grid is arranged on the back surface 11 of the silicon substrate 1, and the first pad 4 is directly printed on the first fine grid 2, and the second pad 5 is directly printed on the second fine grid 3. The back-contact solar cell can also be a back-contact solar cell with a main grid. Specifically, the back-contact solar cell includes a first main grid 8 connected to the first fine grid 2 and a second main grid 9 connected to the second fine grid 3. The first pad 4 is printed on the first main grid 8, and the second pad 5 is printed on the second main grid 9. Among them, only the case where the back-contact solar cell is a back-contact solar cell with a main grid is schematically shown in the drawings. Among them, the number of the first test structure 6 and the second test structure 7 is the same. One first test structure 6 and one second test structure 7 form a pair of test structures for the electrical performance test of the back-contact solar cell. Among them, the first test structure 6 and the second test structure 7 are arranged adjacent to each other, and the specific number of the first test structure 6 and the second test structure 7 is not limited. The first test structure 6 and the second test structure 7 can be 1, 2, 3 or 4 respectively.

[0046] A back-contact solar cell provided by an embodiment of the present invention includes at least one first test structure 6 and at least one second test structure 7 arranged on the back surface 11 of the silicon substrate 1. The first test structure 6 includes two third pads 61 arranged at intervals along the first direction Y, and the third pads 61 are electrically connected to the first fine grid 2; the second test structure 7 includes two fourth pads 71 arranged adjacent to each other along the first direction Y, and the fourth pads 71 are electrically connected to the second fine grid 3. The two third pads 61 of the first test structure 6 and the two fourth pads 71 of the second test structure 7 are used to contact the test probes of the test equipment. Of course, the two third pads 61 of the first test structure 6 and the two fourth pads 71 of the second test structure 7 can also be used for welding the bus bars. When performing current test and voltage test on the back-contact battery, the current test probes of the test equipment respectively contact one third pad 61 of the first test structure 6 and one fourth pad 71 of the second test structure 7, and the voltage test probes of the test equipment contact the other third pad 61 of the first test structure 6 and the other fourth pad 71 of the second test structure 7, so as to form corresponding current test circuits and voltage test circuits.

[0047] In the embodiment of the present invention, the first pad 4 and the third pad 61 have the same dimension in the first direction Y, and the first pad 4 and the third pad 61 have the same dimension in the second direction X. It can be understood that the dimensions of the first pad 4 and the third pad 61 in the first direction Y are exactly the same or the difference is within the allowable processing error range, and the dimensions of the first pad 4 and the third pad 61 in the second direction X are exactly the same or the difference is within the allowable processing error range. Similarly, the fourth pad 71 and the second pad 5 have the same dimension in the first direction Y, and the fourth pad 71 and the second pad 5 have the same dimension in the second direction X. It can be understood that the dimensions of the fourth pad 71 and the second pad 5 in the first direction Y are exactly the same or the difference is within the allowable processing error range, and the dimensions of the fourth pad 71 and the second pad 5 in the second direction X are exactly the same or the difference is within the allowable processing error range. Among them, the shapes of the third pad 61 and the first pad 4 may be the same or different. The shapes of the fourth pad 71 and the second pad 5 may be exactly the same or different. Preferably, the shapes of the third pad 61 and the first pad 4 are the same, and the shapes of the fourth pad 71 and the second pad 5 are the same.

[0048] Please refer to Figure 2 and Figure 3 , specifically, the dimension of the third pad 61 in the first direction Y is the same as that of the first pad 4 in the first direction Y, and the dimension of the third pad 61 in the second direction X is the same as that of the first pad 4 in the second direction X, that is, the length W2 of the third pad 61 is equal to the length W4 of the first pad 4, and the width W1 of the third pad 61 is equal to the width W3 of the first pad 4. Please refer to Figure 2 and Figure 4 , the fourth pad 71 and the second pad 5 have the same dimension. It can be understood that the dimension of the fourth pad 71 in the first direction Y is the same as that of the second pad 5 in the first direction Y, and the dimension of the fourth pad 71 in the second direction X is the same as that of the second pad 5 in the second direction X, that is, the length W6 of the fourth pad 71 is equal to the length W8 of the second pad 5, and the width W5 of the fourth pad 71 is equal to the width W7 of the second pad 5. Among them, the second direction X is perpendicular to the first direction Y.

[0049] Among them, the specific shapes of the first pad 4, the second pad 5, the third pad 61, and the fourth pad 71 are not limited, and can be square, circular, pentagonal, hexagonal, heptagonal, octagonal, elliptical and other shapes. Of course, the first pad 4, the second pad 5, the third pad 61, and the fourth pad 71 can also be other irregular shapes. Among them, the figures only show the case where the first pad 4, the second pad 5, the third pad 61, and the fourth pad 71 are all octagonal.

[0050] An embodiment of the present invention provides a back-contact solar cell. By setting the first test structure 6 to include two third pads 61 spaced along the first direction Y, the third pads 61 have the same size as the first pads 4 along the first direction Y, and the third pads 61 have the same size as the first pads 4 along the second direction X. The spacing L1 between two adjacent first pads 4 along the first direction Y is greater than the spacing L2 between the two third pads 61 of the first test structure 6, or the distance L11 between the third pad 61 and the adjacent first pad 4 along the first direction Y is greater than the spacing L2 between the two third pads 61 of the first test structure 6. Wherein, the distance L11 between the third pad 61 and the adjacent first pad 4 along the first direction Y is the distance from the third pad 61 to the first pad 4 closest to the third pad 61 along the first direction Y, and L11 and L1 may be the same or different.

[0051] Since the first test structure 6 is set to two small-sized third pads 61 spaced apart, and there is no pad structure between the two third pads 61, the width design of the break in the second fine grid 3 in the area between the two third pads 61 can be reduced. Thus, the total length of the second fine grid 3 can be increased, the carrier collection effect of the second fine grid 3 can be improved, and the battery efficiency can be further improved. At the same time, the second test structure 7 is set to include two small-sized fourth pads 71 spaced along the first direction Y. The fourth pads 71 have the same size as the second pads 5 along the first direction Y, and the fourth pads 71 have the same size as the second pads 5 along the second direction X. The spacing L3 between two adjacent second pads 5 along the first direction Y is greater than the spacing L4 between the two fourth pads 71 of the second test structure 7, or the distance L12 between the fourth pad 71 and the adjacent second pad 5 along the first direction Y is greater than the spacing L4 between the two fourth pads 71 of the second test structure 7. Wherein, the distance L12 between the fourth pad 71 and the adjacent second pad 5 along the first direction Y is the distance from the fourth pad 71 to the second pad 5 closest to the fourth pad 71 along the first direction Y, and L12 and L3 may be the same or different. Since there is no pad structure between the two fourth pads 71, the width design of the break in the first fine grid 2 in the area between the two fourth pads 71 can be reduced. Thus, the total length of the first fine grid 2 can be increased, the carrier collection effect of the first fine grid 2 can be improved, and the battery efficiency can be further improved.

[0052] Moreover, the length of a single test pad of a back-contact solar cell in the related art (the dimension in the first direction Y) is usually more than three times the length of the first pad or the second pad. However, the sum of the lengths W2 of the two third pads 61 of the first test structure 6 of the present invention is only twice the length of the first pad 4, and the sum of the lengths W6 of the two fourth pads 71 of the first test structure 6 is only twice the length of the second pad 5. Therefore, the pad length dimensions of the first test structure 6 and the second test structure 7 can be greatly reduced, the amount of paste used for the first test structure 6 and the second test structure 7 can be reduced, the printing cost of the first test structure 6 and the second test structure 7 can be lowered, thereby reducing the printing cost of the back-contact solar cell, and further reducing the production cost of the back-contact solar cell. In addition, since the third pad 61 has the same size as the first pad 4 and the fourth pad 71 has the same size as the second pad 5, it is convenient for the design and printing preparation of each pad.

[0053] In the embodiment of the present invention, the sizes of the first pad 4 and the second pad 5 are the pad sizes of a conventional back-contact solar cell, and the sizes of the first pad 4 and the second pad 5 can be flexibly set according to actual needs. Among them, the shape sizes of the first pad 4 and the second pad 5 can be the same or different. Among them, the number of groups of the first pad 4 and the second pad 5 is not limited, and the first pad 4 and the second pad 5 can be respectively set as a single group or multiple groups. Preferably, the back-contact solar cell includes multiple groups of the first pad 4 and multiple groups of the second pad 5, and the multiple groups of the first pad 4 and the multiple groups of the second pad 5 are alternately arranged at intervals in the second direction X in sequence, and the number of groups of the first pad 4 and the number of groups of the second pad 5 are adapted to the number of solder tapes. In addition, the number of the first pads 4 included in each group of the first pad 4 and the number of the second pads 5 included in each group of the second pad 5 are not limited. Each group of the first pad 4 can include a single first pad 4 or multiple first pads 4; each group of the second pad 5 can include a single second pad 5 or multiple second pads 5. Preferably, each group of the first pad 4 includes multiple first pads 4 arranged at intervals in the first direction Y in sequence, and each group of the second pad 5 includes multiple second pads 5 arranged at intervals in the first direction Y in sequence.

[0054] As a preferred embodiment of the present invention, the shape sizes of the first pad 4, the second pad 5, the third pad 61, and the fourth pad 71 are all the same. Since the shape sizes of the first pad 4, the second pad 5, the third pad 61, and the fourth pad 71 are all the same, there is only a single shape specification of pads on the entire cell, which is more convenient for the design and printing preparation of each pad.

[0055] As an embodiment of the present invention, it includes:

[0056] A plurality of first main gates 8 are disposed on the back surface 11 of the silicon substrate 1. The first main gates 8 extend along the first direction Y and are connected to the first fine gates 2. The first main gates 8 are spaced apart from the second fine gates 3. A plurality of first pads 4 are sequentially spaced along the first direction Y on the first main gates 8. The first test structure 6 is disposed on the first main gates 8; and

[0057] A plurality of second main gates 9 are disposed on the back surface 11 of the silicon substrate 1. The plurality of second main gates 9 and the plurality of first main gates 8 are alternately arranged in sequence along the second direction X. The second main gates 9 extend along the first direction Y and are connected to the second fine gates 3. The second main gates 9 are spaced apart from the first fine gates 2. A plurality of second pads 5 are sequentially spaced along the first direction Y on the second main gates 9. The second test structure 7 is disposed on the second main gates 9. Optionally, the first test structure 6 and the second test structure 7 are respectively disposed on adjacent first main gates 8 and second main gates 9.

[0058] In this embodiment, the first main gate 8 is connected to a plurality of first fine gates 2. Each group of first pads 4 is disposed on the first main gate 8, and the number of groups of the first pads 4 is the same as the number of the first main gates 8. Each group of second pads 5 is disposed on the second main gate 9, and the number of groups of the second pads 5 is the same as the number of the second main gates 9. The adjacent two third pads 61 of the first test structure 6 are electrically connected through the first main gate 8. The second main gate 9 is connected to a plurality of second fine gates 3, and the adjacent two fourth pads 71 of the second test structure 7 are electrically connected through the second main gate 9. Among them, the first main gate 8 is used to collect the corresponding carriers on the first fine gate 2, and the second main gate 9 is used to collect the corresponding carriers on the second fine gate 3. Due to the arrangement of the first main gate 8 and the second main gate 9, it is beneficial to better collect carriers, and it is convenient for the printing setting of the pads and the welding of the pads and the welding tapes.

[0059] Please refer to Figures 2-4 , as an embodiment of the present invention, the distance between the two third pads 61 of the first test structure 6 is L2, the distance between two adjacent second fine gates 3 is L5, L2 is greater than or equal to L5, and L2 is less than or equal to 3L5.

[0060] In this embodiment, the second fine grids 3 are arranged at equal intervals in sequence, and the interval L5 between two adjacent second fine grids 3 is the distance between two adjacent second fine grids 3 along the first direction Y. By controlling the interval L2 between the two third pads 61 of the first test structure 6 to be greater than or equal to L5 and less than or equal to 3L5, the interval L2 between the two third pads 61 is controlled within a more appropriate range, which can not only prevent the interval L2 between the two third pads 61 from being too large and inconvenient for the contact test of the current test probe and the voltage test probe, but also avoid the discontinuity width of the second fine grid 3 at the position between the two third pads 61 from being too large due to the interval L2 between the two third pads 61 being too small. Thus, it is not only convenient for the electrical performance test of the back-contact solar cell, but also beneficial to improving the carrier collection effect of the second fine grid 3, thereby improving the battery efficiency.

[0061] In addition, L2 is greater than or equal to L5 and less than or equal to 3L5, which can ensure that the non-pad area between the two third pads 61 straddles 1 to 3 second fine grids 3, and can reduce the width design of the discontinuity of 1 to 3 second fine grids 3 at the position between the two third pads 61. Thus, the carrier collection effect of the second fine grid 3 can be further improved, and the battery efficiency can be improved.

[0062] As an embodiment of the present invention, the interval between the two fourth pads 71 of the second test structure 7 is L4, the interval between two adjacent first fine grids 2 is L6, L4 is greater than or equal to L6, and L4 is less than or equal to 3L6.

[0063] In this embodiment, the first fine grids 2 are arranged at equal intervals in sequence, and the interval L6 between two adjacent first fine grids 2 is the distance between two adjacent first fine grids 2 along the first direction Y. Optionally, the first fine grids 2 and the second fine grids 3 are arranged alternately at equal intervals, that is, L5 is equal to L6; the interval L4 between the two fourth pads 71 of the second test structure 7 is equal to the interval L2 between the two third pads 61 of the first test structure 6, which is convenient for the design and printing of the back-contact solar cell. In addition, optionally, the interval L1 between two adjacent first pads 4 along the first direction Y is equal to the interval L3 between two adjacent second pads 5 along the first direction Y.

[0064] In this embodiment, by controlling the interval L4 between the two fourth pads 71 of the second test structure 7 to be greater than or equal to L6 and less than or equal to 3L6, the interval L4 between the two fourth pads 71 is controlled within a more appropriate range, which can not only prevent the interval L4 between the two fourth pads 71 from being too large and inconvenient for the contact test of the current test probe and the voltage test probe, but also avoid the discontinuity width of the first fine grid 2 at the position between the two fourth pads 71 from being too large due to the interval L4 between the two fourth pads 71 being too small. Thus, it is not only convenient for the electrical performance test of the back-contact solar cell, but also beneficial to improving the carrier collection effect of the first fine grid 2, thereby improving the battery efficiency.

[0065] As an embodiment of the present invention, each group of first pads 4 includes a plurality of first pads 4 arranged at intervals along the first direction Y, and the ratio of the pitch L1 between two adjacent first pads 4 in the first direction Y to the pitch L2 between two third pads 61 of the first test structure 6 is 8 to 15.

[0066] In this embodiment, controlling the ratio of the pitch L1 between two adjacent first pads 4 in the first direction Y to the pitch L2 between two third pads 61 of the first test structure 6 to be 8 to 15 is beneficial to the welding effect between the first pads 4 and the welding tape, and is convenient for the contact test between the two third pads 61 of the first test structure 6 and the current test probe and voltage test probe of the test equipment respectively; moreover, it is also beneficial to improving the carrier collection effect of the second fine grid 3, thereby improving the battery efficiency.

[0067] As an embodiment of the present invention, the ratio of the pitch L1 between two adjacent first pads 4 in the first direction Y to the pitch L2 between two third pads 61 of the first test structure 6 is 9 to 10.

[0068] In this embodiment, further controlling the ratio of the pitch L1 between two adjacent first pads 4 in the first direction Y to the pitch L2 between two third pads 61 of the first test structure 6 to be 9 to 10 is further beneficial to the welding effect between the first pads 4 and the welding tape, and is further convenient for the contact test between the two third pads 61 of the first test structure 6 and the current test probe and voltage test probe respectively.

[0069] As an embodiment of the present invention, each group of second pads 5 includes a plurality of second pads 5 arranged at intervals along the first direction Y, and the ratio of the pitch L3 between two adjacent second pads 5 in the first direction Y to the pitch L4 between two fourth pads 71 of the second test structure 7 is 8 to 15.

[0070] In this embodiment, the ratio of the pitch L3 between two adjacent second pads 5 in the first direction Y to the pitch L4 between two fourth pads 71 of the second test structure 7 being 8 to 15 is beneficial to the welding effect between the second pads 5 and the welding tape, and is convenient for the contact test between the two fourth pads 71 of the second test structure 7 and the current test probe and voltage test probe of the test equipment respectively to complete the test. Moreover, it is also beneficial to improving the carrier collection effect of the first fine grid 2, thereby improving the battery efficiency. Further, the ratio of the pitch L3 between two adjacent second pads 5 to the pitch L4 between two fourth pads 71 of the second test structure 7 being 9 to 10 is beneficial to the welding effect between the second pads 5 and the welding tape, and is further convenient for the contact test between the two fourth pads 71 of the second test structure 7 and the current test probe and voltage test probe respectively.

[0071] As an embodiment of the present invention, the distance L2 between the two third pads 61 of the first test structure 6 is greater than the length W2 of the third pad 61; the distance L4 between the two fourth pads 71 of the second test structure 7 is greater than the length W6 of the fourth pad 71.

[0072] In this embodiment, the distance L2 between the two third pads 61 of the first test structure 6 is the distance between the two third pads 61 along the first direction Y, and the length W2 of the third pad 61 is the dimension of the third pad 61 along the first direction Y. Since the distance L2 between the two third pads 61 of the first test structure 6 is greater than the length W2 of the third pad 61, it is beneficial for a larger number of first fine grids 2 to reduce the break width in the area between the two third pads 61, which is beneficial for further improving the carrier collection effect of the second fine grid 3, and thus improving the battery efficiency. Similarly, the distance L4 between the two fourth pads 71 of the second test structure 7 is greater than the length W6 of the fourth pad 71, and the length W6 of the fourth pad 71 is the dimension of the fourth pad 71 along the first direction Y, which is beneficial for a larger number of first fine grids 2 to reduce the width design of the break in the area between the two fourth pads 71, which is beneficial for further improving the carrier collection effect of the first fine grid 2, and thus improving the battery efficiency.

[0073] As an embodiment of the present invention, the distance L2 between the two third pads 61 of the first test structure 6 is less than or equal to twice the length W2 of the third pad 61; the distance L4 between the two fourth pads 71 of the second test structure 7 is less than or equal to twice the length W6 of the fourth pad 71.

[0074] In this embodiment, by controlling the distance L2 between the two third pads 61 of the first test structure 6 to be less than or equal to twice the length W2 of the third pad 61, and controlling the distance L4 between the two fourth pads 71 of the second test structure 7 to be less than or equal to twice the length W6 of the fourth pad 71, it is possible to prevent the distances L2 between the two third pads 61 and L4 between the two fourth pads 71 from being too large and inconvenient for the contact test of the current test probe and the voltage test probe, and it is also possible to avoid the distances L2 between the two third pads 61 and L4 between the two fourth pads 71 from being too small, which can reduce the break width design of the second fine grid 3 at the position between the two third pads 61 and reduce the break width design of the first fine grid 2 at the position between the two fourth pads 71, which is beneficial for improving the carrier collection effect of the fine grid and thus improving the battery efficiency.

[0075] As an embodiment of the present invention, the first test structure 6 includes a first connecting portion 62 connecting the two third pads 61. The width of the first connecting portion 62 is less than the width W1 of the third pad 61. The second fine grid 3 forms a first break 31 at the position of the first connecting portion 62, and the second fine grid 3 is spaced apart from the first connecting portion 62 through the first break 31;

[0076] The second fine grid 3 forms a second break 32 at the position of the third pad 61. The second fine grid 3 is spaced from the third pad 61 through the second break 32, and the width L7 of the first break 31 is less than the width L8 of the second break 32.

[0077] In this embodiment, the two third pads 61 are electrically connected through the first connection part 62. The first connection part 62 can be a part of the first main grid 8. The two third pads 61 are directly printed on the first main grid 8, or the first connection part 62 can also be separately printed and prepared. The width directions of the third pad 61, the first break 31, and the second break 32 are all along the second direction X. Since the width of the first break 31 is less than the width of the second break 32, that is, the break width of the second fine grid 3 at the position of the first connection part 62 is less than the break width of the second fine grid 3 at the position of the first pad 4, the width of the first break 31 of the second fine grid 3 at the position of the first connection part 62 can be reduced, the total length of the second fine grid 3 at the position of the first connection part 62 can be increased, the carrier collection effect of the second fine grid 3 at the position of the first connection part 62 can be improved, and thus the battery efficiency can be improved.

[0078] As an embodiment of the present invention, the second test structure 7 includes a second connection part 72 connecting two fourth pads 71. The width of the second connection part 72 is less than the width W5 of the fourth pad 71. The first fine grid 2 forms a third break 21 at the position of the second connection part 72. The first fine grid 2 is spaced from the second connection part 72 through the third break 21;

[0079] The first fine grid 2 forms a fourth break 22 at the position of the fourth pad 71. The first fine grid 2 is spaced from the fourth pad 71 through the fourth break 22, and the width L9 of the third break 21 is less than the width L10 of the fourth break 22.

[0080] In this embodiment, the two fourth pads 71 are electrically connected through the second connection part 72. The second connection part 72 can be a part of the second main grid 9. The two fourth pads 71 are directly printed on the second main grid 9, or the second connection part 72 can also be separately printed and prepared. The width directions of the fourth pad 71, the third break 21, and the fourth break 22 are all along the second direction X. Since the width of the third break 21 is less than the width of the fourth break 22, the width of the third break 21 of the first fine grid 2 at the position of the second connection part 72 can be reduced, the length of the first fine grid 2 at the position of the second connection part 72 can be increased, the carrier collection effect of the first fine grid 2 at the position of the second connection part 72 can be improved, and thus the battery efficiency can be improved.

[0081] As an embodiment of the present invention, the width of the first pad 4 is 3 to 5 times the width of the first connecting portion 62; the width of the second pad 5 is 3 to 5 times the width of the second connecting portion 72, which can further improve the carrier collection effect of the second fine grid 3 at the position of the first connecting portion 62 and improve the carrier collection effect of the first fine grid 2 at the position of the second connecting portion 72, thereby improving the battery efficiency.

[0082] As an embodiment of the present invention, the width of the first connecting portion 62 is uniformly set, which is convenient for the printing and processing of the first test structure 6.

[0083] In some other embodiments, the width of the middle position of the first connecting portion 62 is smaller than the width of the first connecting portion 62 near the third pad 61. That is, the width of the first connecting portion 62 near the middle position is smaller than the width of the first connecting portion 62 near the third pad 61, so that the width of the middle position of the first connecting portion 62 is smaller than the width of the two end positions of the first connecting portion 62, which can further reduce the width design of the discontinuity of the second fine grid 3 at the position of the first connecting portion 62, and can further improve the carrier collection effect of the second fine grid 3, thereby improving the battery efficiency. Similarly, the width of the middle position of the second connecting portion 72 is smaller than the width of the second connecting portion 72 near the fourth pad 71. That is, the width of the second connecting portion 72 near the middle position is smaller than the width of the second connecting portion 72 near the fourth pad 71, so that the width of the middle position of the second connecting portion 72 is smaller than the width of the two end positions of the second connecting portion 72, which can further reduce the width design of the discontinuity of the first fine grid 2 at the position of the second connecting portion 72, and can further improve the carrier collection effect of the second fine grid 3, thereby improving the battery efficiency.

[0084] The embodiment of the present invention further provides a battery assembly, which includes the back contact solar cell of the above embodiment. It should be noted that this battery assembly has the same or similar beneficial effects as the above back contact solar cell, and the relevant parts between the two can be referred to each other. To avoid repetition, it will not be elaborated here.

[0085] The embodiment of the present invention further provides a photovoltaic system, which includes the battery assembly of the above embodiment. It should be noted that this photovoltaic system has the same or similar beneficial effects as the above battery assembly, and the relevant parts between the two can be referred to each other. To avoid repetition, it will not be elaborated here.

[0086] In this embodiment, the photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a rooftop power station, a water surface power station, etc., or can also be applied to devices or apparatuses that use solar energy for power generation, such as a user solar power supply, a solar street lamp, a solar vehicle, a solar building, and so on. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be applied in all fields that require solar power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a busbar box, and an inverter. The photovoltaic array can be an array combination of multiple battery components. For example, multiple battery components can form multiple photovoltaic arrays. The photovoltaic array is connected to the busbar box, and the busbar box can converge the current generated by the photovoltaic array. After the converged current flows through the inverter and is converted into alternating current required by the commercial power grid, it is connected to the commercial power grid to achieve solar power supply.

[0087] In the description of this specification, the description with reference to terms such as "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0088] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A back-contact solar cell, characterized in that, Comprising: A silicon substrate; A plurality of first fine grids and a plurality of second fine grids disposed on the back surface of the silicon substrate, the plurality of first fine grids and the plurality of second fine grids are alternately arranged at intervals in a first direction in sequence, both the first fine grids and the second fine grids extend in a second direction, and the second direction intersects with the first direction; At least one set of first pads disposed on the back surface of the silicon substrate, each set of the first pads includes at least one first pad, and the first pad is electrically connected to the first fine grid; At least one set of second pads disposed on the back surface of the silicon substrate, each set of the second pads includes at least one second pad, and the second pad is electrically connected to the second fine grid; At least one first test structure disposed on the back surface of the silicon substrate, the first test structure includes two third pads disposed at intervals in the first direction and electrically connected to each other, the third pads are electrically connected to the first fine grids, and the third pads are spaced from the second fine grids; the third pads and the first pads have the same size in the first direction, the third pads and the first pads have the same size in the second direction, the distance between two adjacent first pads in the first direction is greater than the distance between the two third pads of the first test structure or the distance between the third pad and the adjacent first pad in the first direction is greater than the distance between the two third pads of the first test structure; And At least one second test structure disposed on the back surface of the silicon substrate, the second test structure includes two fourth pads disposed adjacent to each other in the first direction and electrically connected to each other, the fourth pads are electrically connected to the second fine grids, the fourth pads are spaced from the first fine grids, the fourth pads and the second pads have the same size in the first direction, the fourth pads and the second pads have the same size in the second direction, the distance between two adjacent second pads in the first direction is greater than the distance between the two fourth pads of the second test structure or the distance between the fourth pad and the adjacent second pad in the first direction is greater than the distance between the two fourth pads of the second test structure.

2. The back contact solar cell according to claim 1, characterized in that, The first pads, the second pads, the third pads, and the fourth pads have the same shape and size.

3. The back contact solar cell according to claim 1, characterized in that, The distance between the two third pads of the first test structure is L2, the distance between two adjacent second fine grids is L5, L2 is greater than or equal to L5 and less than or equal to 3L5.

4. The back contact solar cell according to claim 1 or 3, characterized in that, The distance between the two fourth pads of the second test structure is L4, the distance between two adjacent first fine grids is L6, L4 is greater than or equal to L6 and less than or equal to 3L6.

5. The back-contact solar cell according to claim 1, characterized in that, Each group of the first pads includes a plurality of the first pads arranged at intervals along the first direction, and the ratio of the distance between two adjacent ones of the first pads in the first direction to the distance between two third pads of the first test structure is 8 to 15; and / or, each group of the second pads includes a plurality of the second pads arranged at intervals along the first direction, and the ratio of the distance between two adjacent ones of the second pads in the first direction to the distance between two fourth pads of the second test structure is 8 to 15.

6. The back contact solar cell according to claim 5, characterized in that, The ratio of the distance between two adjacent ones of the first pads in the first direction to the distance between two third pads of the first test structure is 9 to 10; and / or, the ratio of the distance between two adjacent ones of the second pads in the first direction to the distance between two fourth pads of the second test structure is 9 to 10.

7. The back contact solar cell according to claim 1, wherein, The distance between two third pads of the first test structure is greater than the length of the third pad; and / or, the distance between two fourth pads of the second test structure is greater than the length of the fourth pad.

8. The back-contact solar cell according to claim 1, characterized in that, The distance between two third pads of the first test structure is less than or equal to twice the length of the third pad; the distance between two fourth pads of the second test structure is less than or equal to twice the length of the fourth pad.

9. The back contact solar cell according to claim 1, wherein, The first test structure includes a first connecting portion connecting two third pads, the width of the first connecting portion is less than the width of the third pad, the second fine grid forms a first break at the position of the first connecting portion, and the second fine grid is spaced from the first connecting portion through the first break. The second fine grid forms a second break at the position of the third pad, the second fine grid is spaced from the third pad through the second break, and the width of the first break is less than the width of the second break.

10. The back-contact solar cell according to claim 9, characterized in that, The second test structure includes a second connecting portion connecting two fourth pads, the width of the second connecting portion is less than the width of the fourth pad, the first fine grid forms a third break at the position of the second connecting portion, and the first fine grid is spaced from the second connecting portion through the third break. The first fine grid forms a fourth break at the position of the fourth pad, the first fine grid is spaced from the fourth pad through the fourth break, and the width of the third break is less than the width of the fourth break.

11. The back contact solar cell according to claim 10, wherein, The width of the first pad is 3 to 5 times the width of the first connecting portion; and / or, the width of the second pad is 3 to 5 times the width of the second connecting portion.

12. The back contact solar cell according to claim 1, characterized in that, Including: A plurality of first main grids provided on the back surface of the silicon substrate, the first main grids extend along the first direction and are connected to the first fine grid, the first main grids are spaced from the second fine grid, a plurality of the first pads are provided on the first main grids at intervals in the first direction, and the first test structure is arranged on the first main grid; and A plurality of second main grids disposed on the back surface of the silicon substrate, the plurality of second main grids and the plurality of first main grids are alternately arranged in sequence along the second direction, the second main grids extend along the first direction and are connected to the second fine grids, the second main grids are spaced from the first fine grids, and a plurality of the second pads are arranged on the second main grids at intervals along the first direction, and the second test structure is disposed on the second main grids.

13. A battery assembly, characterized in that, A back-contact solar cell according to any one of claims 1 to 12.

14. A photovoltaic system, characterized in that, A battery module according to claim 13.

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