Back contact solar cell and photovoltaic module

Abstract

A back contact solar cell includes a cell substrate, a plurality of collector electrodes, and a plurality of pairs of voltage test points. The battery substrate includes a target surface. The collector electrodes extend on the target surface in the first direction and comprise the first collector electrode and the second collector electrode which are opposite in polarity. The first collector electrodes and the second collector electrodes are alternately arranged along a second direction different from the first direction. And at least one pair of voltage test points are arranged on the two sides of the first central axis of the battery substrate along the second direction respectively. In the at least one pair of voltage test points, the distance between the voltage test point close to the first central axis and the first central axis is D1, the distance between the voltage test point away from the first central axis and the first edge of the battery substrate is D2, D1 is smaller than D2, and the first edge comprises an edge part, extending in the second direction, of the battery substrate. The utility model also provides a photovoltaic module comprising the back contact solar cell. The stability and the accuracy of testing the open-circuit voltage are improved by setting the voltage test point at the specific position of the battery substrate.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and more specifically, to a back-contact solar cell and a photovoltaic module including the back-contact solar cell. Background Art

[0002] In the production process of solar cells, it is necessary to print a plurality of fine grids arranged along a first direction on the cell substrate, so as to collect the current generated on the surface of the cell through the plurality of fine grids. In addition, the cell substrate is provided with a plurality of main grids along a second direction intersecting the first direction, so as to collect the current collected by the fine grids through the main grids. In order to improve the conversion efficiency of solar cells and reduce production costs, the main grid-free battery technology has emerged. A main grid-free cell generally refers to a cell that is based on a conventional cell, but at least part of the main grid lines are removed and the fine grids are retained. Due to the absence of main grid lines, on the one hand, the amount of conductive paste used can be greatly reduced, the effective illumination area of ​​the cell can be increased, and the recombination between metal and semiconductor can be reduced, thereby improving the photoelectric conversion efficiency of the cell.

[0003] Before solar cells are made into photovoltaic modules, they usually need to be tested and sorted. The test contents include open circuit voltage, short circuit current, etc. To test the open circuit voltage, it is necessary to set conductive test points on the cell in advance, and then use the tester probe to align the connection test points for measurement. The cell has a certain area size. In order to accurately obtain the open circuit voltage data of the cell, more voltage test points are usually designed in the electrode pattern of the cell so that they are evenly distributed on the entire cell. For traditional bifacial cells, the positive and negative electrodes (N-type fine grid and P-type fine grid) are located on the opposite sides of the cell, and the N-type fine grid and P-type fine grid are arranged relatively loosely, so there is sufficient space to set more voltage test points to obtain the open circuit voltage measurement value. For back contact (BC) cells, since the positive and negative electrodes (N-type fine gates and P-type fine gates) are located on the same side of the cell, the fine gates for collecting carriers are relatively crowded, and the location and number of voltage test points are crucial. Setting too many voltage test points will compress the fine gate area, which will lead to a decrease in the conversion efficiency of the cell; in addition, too many voltage test points will increase the consumption of silver paste, which will increase the cost; and setting too few voltage test points may lead to poor test reliability. In addition, a functional film layer is formed on the cell, such as a doped polysilicon layer. Usually, the portion of the functional film layer located in the edge area is relatively uneven, and the probability of defects is high, while the portion of the functional film layer located in the middle area has relatively good film quality. Therefore, the position of the open voltage test point on the cell cannot be set arbitrarily, otherwise it will lead to poor test stability and accuracy. Utility Model Content

[0004] In view of this, the present application provides a back-contact solar cell, comprising:

[0005] a battery substrate, the battery substrate comprising a first surface and a second surface opposite to each other, wherein one of the first surface and the second surface is a target surface;

[0006] a plurality of collector electrodes, located on the target surface, the plurality of collector electrodes extending along a first direction, the plurality of collector electrodes comprising a first collector electrode and a second collector electrode with opposite polarities, at least a portion of the first collector electrodes and at least a portion of the second collector electrodes being alternately arranged along a second direction, the first direction being different from the second direction;

[0007] a plurality of bus electrodes, located on the target surface, each of the bus electrodes extending along the second direction, the plurality of bus electrodes comprising a plurality of first bus electrodes and a plurality of second bus electrodes with opposite polarities, the plurality of first bus electrodes and the plurality of second bus electrodes being arranged at intervals along the first direction, the first bus electrodes being electrically connected to at least a portion of the first collector electrodes, and the second bus electrodes being electrically connected to at least a portion of the second collector electrodes;

[0008] At least one pair of voltage test points are respectively arranged on both sides of the first central axis of the battery substrate, the first central axis extends along the second direction, and the at least one pair of voltage test points are respectively located on a pair of the first bus electrode and the second bus electrode;

[0009] Among the at least one pair of voltage test points, the distance between the voltage test point close to the first central axis and the first central axis is D1, and the distance between the voltage test point far from the first central axis and the first edge of the battery substrate is D2, D1<D2, and the first edge includes the edge portion of the battery substrate extending along the second direction.

[0010] By setting voltage test points at specific positions on the battery substrate and avoiding the influence of the PL dark area on the battery on the test results, a pair of open-circuit voltage test points are no longer set in the middle area between the first central axis and the first edge of the battery substrate, thereby improving the stability and accuracy of the open-circuit voltage test. At the same time, it also avoids the problem of increased shading loss, reduced fine grid area, and increased silver paste loss caused by designing too many voltage test points.

[0011] In some embodiments, in the at least one pair of voltage test points, center points of the two voltage test points are staggered from each other along the second direction, and / or,

[0012] The two pairs of voltage test points located on both sides of the first central axis at least partially overlap after being translated along the first direction, and the two voltage test points that at least partially overlap have the same polarity.

[0013] The positive and negative open-circuit voltage test points are arranged in a staggered manner to avoid disconnection of more collector electrodes of opposite polarity to avoid open-circuit voltage test points, thereby reducing the formation of more dead zones and increasing short-circuit current. The two pairs of voltage test points located on both sides of the first central axis are translated along the first direction and overlapped, thus ensuring the symmetry of the test positions of the voltage test points on both sides of the first central axis Y, improving the test accuracy, and at the same time the test fixture has a repeated unit structure, reducing the difficulty of preparing the test fixture.

[0014] In some embodiments, when the number of the busbar electrodes is an odd number, along the first direction, the number of busbar electrodes between the voltage test point close to the first central axis in the at least one pair of voltage test points and the first central axis is equal to the number of busbar electrodes between the voltage test point far from the first central axis in the at least one pair of voltage test points and the first edge of the battery substrate;

[0015] When the number of bus electrodes is an even number, then along the first direction, the number of bus electrodes between the voltage test point close to the first central axis in the at least one pair of voltage test points and the first central axis is less than the number of bus electrodes between the voltage test point away from the first central axis in the at least one pair of voltage test points and the first edge of the battery substrate.

[0016] In this way, at least one pair of voltage test points on both sides of the first central axis are basically set at the middle position along the first direction, which can improve the accuracy and stability of the open circuit voltage test and also match different numbers of bus electrodes.

[0017] In some embodiments, the battery substrate further includes a second edge and a third edge that are relatively spaced apart, the second edge and the third edge each include an edge portion that is at least parallel to the first direction, the battery substrate further includes a plurality of interconnecting portions that are spaced apart, and each of the bus electrodes is collinear with at least a portion of the interconnecting portions;

[0018] When the number of interconnections collinear with each of the bus electrodes is an odd number, then along the second direction, in each pair of the voltage test points, the number of interconnections between the voltage test point close to the second edge and the second edge is less than the number of interconnections between the voltage test point close to the third edge and the third edge;

[0019] When the number of the interconnections co-linear with each of the bus electrodes is an even number, then along the second direction, in each pair of the voltage test points, the number of interconnections between the voltage test points close to the second edge and the second edge is equal to the number of interconnections between the voltage test points close to the third edge and the third edge.

[0020] In this way, at least one pair of voltage test points on both sides of the first central axis are basically set at the middle position along the second direction, which can improve the accuracy and stability of the test and also match different numbers of interconnections.

[0021] In some embodiments, when the number of busbar electrodes located on one side of the first central axis is ≥6, at least two pairs of voltage test points are disposed on each side of the first central axis.

[0022] As the number of busbar electrodes increases, setting a pair of voltage test points on one side of the first central axis cannot accurately reflect the actual opening voltage value. By setting two pairs of voltage test points, the accuracy of the test can be improved.

[0023] In some embodiments, at least two pairs of voltage test points are disposed on each side of the first central axis, wherein different voltage test points are located on different bus electrodes, and the at least two pairs of voltage test points are staggered along the second direction.

[0024] The two pairs of voltage test points are staggered in the first direction and the second direction, taking into account the open voltage test results at different positions and different numbers, thereby improving the authenticity and accuracy of the test results.

[0025] In some embodiments, at least two pairs of voltage test points are disposed on each side of the first central axis, and the at least two pairs of voltage test points at least partially overlap after translation along the second direction.

[0026] In some embodiments, 2*M>the size of each voltage test point along the second direction is ≥0.8*M, where M is the distance between two adjacent collector electrodes of the same polarity along the second direction.

[0027] The size of the voltage test point is set to a specific range so that it is not too small to meet the minimum size required by the test fixture, and at the same time, the size is not too large to interrupt more collector electrodes of opposite polarity, reduce the formation of more dead zones, and avoid the increase of short-circuit current.

[0028] In some embodiments, the intersection of the first central axis and the first edge is taken as the origin, the X-axis is set by the first edge and the Y-axis is set by the first central axis, the side length of the battery base along the X-axis is a, and the side length along the Y-axis is b / 2, each pair of voltage test points is located in a non-overlapping area between a first rectangle with the Y-axis as the axis of symmetry and a second rectangle with the Y-axis as the axis of symmetry, the coordinates of the vertices of the first rectangle located in the first quadrant are (a / 9, b / 9), and the coordinates of the vertices of the second rectangle located in the first quadrant are (7*a / 18, 7*b / 18).

[0029] By further limiting the location area of ​​the voltage test point, the test accuracy and stability can be further improved.

[0030] The present application also provides a back contact solar cell, comprising:

[0031] A battery substrate, comprising a first surface and a second surface opposite to each other, wherein one of the first surface and the second surface is a target surface; the battery substrate comprises two battery cells arranged along a second direction, each of the battery cells comprising:

[0032] a plurality of collector electrodes, located on the target surface, the plurality of collector electrodes extending along a first direction, the plurality of collector electrodes comprising a first collector electrode and a second collector electrode with opposite polarities, at least a portion of the first collector electrodes and at least a portion of the second collector electrodes being alternately arranged along a second direction, the first direction being different from the second direction;

[0033] a plurality of bus electrodes, located on the target surface, each of the bus electrodes extending along the second direction, the bus electrodes comprising a plurality of first bus electrodes and a plurality of second bus electrodes with opposite polarities, the plurality of first bus electrodes and the plurality of second bus electrodes being arranged at intervals along the first direction, the first bus electrodes being electrically connected to at least a portion of the first collector electrodes, and the second bus electrodes being electrically connected to at least a portion of the second collector electrodes;

[0034] At least one pair of voltage test points are respectively arranged on both sides of the first central axis of each of the battery cells, the first central axis extends along the second direction, and the at least one pair of voltage test points are respectively located on an adjacent pair of the first bus electrode and the second bus electrode;

[0035] Among the at least one pair of voltage test points, the distance between the voltage test point close to the first central axis and the first central axis is D1, and the distance between the voltage test point far from the first central axis and the first edge of the battery substrate is D2, D1<D2, and the first edge includes the edge portion of the battery substrate extending along the second direction.

[0036] In some embodiments, the bus electrodes provided on the two battery cells are at least partially collinear along the second direction and have opposite polarities, and at least two pairs of voltage test points of the two battery cells located on the same side of the first central axis at least partially overlap after translation along the second direction or are symmetrically distributed relative to the second central axis of the battery base along the first direction.

[0037] In some embodiments, in the at least one pair of voltage test points, center points of the two voltage test points are staggered from each other along the second direction, and / or,

[0038] In the same battery unit, two pairs of voltage test points located on both sides of the first central axis at least partially overlap after translation along the first direction, and the two voltage test points that at least partially overlap have the same polarity, and / or,

[0039] The multiple pairs of voltage test points on the battery substrate are centrally symmetrical about the center point of the battery substrate, and / or,

[0040] In the two battery cells, two voltage test points on the bus electrodes that are collinear along the second direction have opposite polarities.

[0041] In some embodiments, the intersection of the first central axis and the second central axis of the battery substrate along the first direction is taken as the origin, the X-axis is set by the second central axis and the Y-axis is set by the first central axis, the side length of the battery substrate along the X-axis is a, and the side length along the Y-axis is b, each pair of voltage test points is located in a non-overlapping area between a first rectangle with the origin as the center point and a second rectangle with the origin as the center point, the coordinates of the vertices of the first rectangle located in the first quadrant are (a / 9, b / 9), and the coordinates of the vertices of the second rectangle located in the first quadrant are (7*a / 18, 7*b / 18).

[0042] A photovoltaic component comprises at least one solar cell as described above and a conductive interconnector, wherein the conductive interconnector is electrically connected to the bus electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the target surface distribution of the solar cell of the embodiment of the present application Figure 1 .

[0044] Figure 2 Schematic diagram of the target surface distribution of the solar cell of the embodiment of the present application Figure 2 .

[0045] Figure 3 Schematic diagram of the electrode pattern on the target surface of a solar cell Figure 1 .

[0046] Figure 4 Schematic diagram of the electrode pattern on the target surface of a battery cell of a solar cell Figure 2 .

[0047] Description of main component symbols:

[0048] Back contact solar cell 100

[0049] PL Dark Zone 101

[0050] Battery substrate 10

[0051] Collecting electrode 20

[0052] First current collecting electrode 20A

[0053] Second current collecting electrode 20B

[0054] Internet Department 23

[0055] Second interconnection portion 23B

[0056] First interconnection portion 23A

[0057] Bus electrode 30

[0058] The first bus electrode 30A

[0059] The second bus electrode 30B

[0060] Voltage test point 60

[0061] First rectangle 40a

[0062] Second rectangle 40b

[0063] The third rectangle 40c

[0064] Fourth rectangle 40d

[0065] Rectangles 50a, 50b, 50c, 50d

[0066] The first central axis Y

[0067] The second central axis X DETAILED DESCRIPTION

[0068] The present application provides a solar cell, which sets a reasonable voltage test point position and number, reduces the number of voltage test points, improves shading loss and reduces the amount of conductive silver paste used, improves open voltage test reliability, and improves the conversion efficiency of the battery while meeting the open circuit voltage test requirements. The voltage test point in the present application is an open circuit voltage test point.

[0069] The open circuit voltage on the surface of solar cells has a certain distribution, and the open circuit voltage at different positions is inconsistent. The brightness of the solar cell at different positions under photoluminescence (PL) corresponds to the open circuit voltage at that position. PL detection is a quality inspection technology for solar cells. It uses light of a specific wavelength to illuminate and excite the solar cell, causing the electrons in the solar cell to transition from the ground state to the excited state, and then emit fluorescence when returning to the ground state. By collecting the fluorescence, the defects of the solar cell, the distribution of impurities, and the luminescence properties of the material can be analyzed. Ideally, the PL on the surface of the cell should be uniform in brightness. However, due to the uneven treatment of different positions of the cell by various processes in the actual production process, there is a difference in the brightness of the PL. Please refer to Figure 1 and Figure 2 , usually the PL dark area 101 is located at the edge areas on both sides of the solar cell 100, usually accounting for about 10% of the area of ​​the solar cell, and the other areas are PL bright areas. According to the PL brightness distribution of the cell, the open circuit voltage distribution of the entire surface can be seen, and the open circuit voltage at the center of the cell is higher than the open circuit voltage at the edge.

[0070] See also Figure 3 The back-contact solar cell 100 according to the embodiment of the present application includes a cell substrate 10 and a plurality of collecting electrodes 20 disposed on the cell substrate 10 .

[0071] In the embodiment of the present application, the battery substrate 10 is a silicon substrate, and some functional layers (not shown) are formed on the surface of the silicon substrate. The battery substrate 10 is in the shape of a thin plate, including a first surface and a second surface relative to each other, wherein at least one of the first surface and the second surface is a target surface. The collector electrode 20 is arranged on the target surface for collecting the current generated by the solar cell after being illuminated. The collector electrode 20 is formed on the target surface of the battery substrate 10 by printing a conductive paste and sintering. Each collector electrode 20 extends along a first direction and a plurality of collector electrodes 20 are arranged at intervals along a second direction, and the first direction is different from the second direction. Preferably, the first direction is perpendicular to the second direction.

[0072] In the embodiment of the present application, the solar cell 100 is a back contact cell, that is, positive and negative electrodes are arranged on the same surface. Figure 3, the collector electrode 20 includes a plurality of first collector electrodes 20A and a plurality of second collector electrodes 20B, and the first collector electrodes 20A and the second collector electrodes 20B have opposite polarities and are electrically insulated. In the embodiment of the present application, the plurality of first collector electrodes 20A and the plurality of second collector electrodes 20B are alternately arranged along the second direction. The first collector electrode 20A and the second collector electrode 20B are N-type fine gates and P-type fine gates to each other. That is, when the first collector electrode 20A is an N-type fine gate, the second collector electrode 20B is a P-type fine gate; when the first collector electrode 20A is a P-type fine gate, the second collector electrode 20B is an N-type fine gate.

[0073] like Figure 3 As shown, in the embodiment of the present application, the back contact solar cell 100 has a main grid, including a plurality of bus electrodes 30, each of which extends along the second direction. The bus electrode 30 includes a first bus electrode 30A and a second bus electrode 30B with opposite polarities. Basically, the first bus electrode 30A and the second bus electrode 30B are arranged alternately along the first direction. A small area of ​​the target area is not excluded, and the first bus electrode 30A and the second bus electrode 30B are not arranged alternately along the first direction. The first bus electrode 30A extends to be electrically connected to the first collector electrode 20A. The second bus electrode 30B extends to be electrically connected to the second collector electrode 20B.

[0074] like Figures 1 to 3 As shown, along the second direction, at least one pair of voltage test points 60 are respectively arranged on both sides of the first central axis Y of the battery substrate 10. Each pair of voltage test points 60 includes a positive electrode test point and a negative electrode test point, and the positive electrode test point and the negative electrode test point are spaced from each other and are both formed by printing conductive paste.

[0075] In the present application, at least one pair of voltage test points 60 on each side of the first central axis Y is respectively arranged on the first bus electrode 30A and the second bus electrode 30B. The positive and negative test points of each pair of voltage test points 60 are respectively arranged on two bus electrodes 30 with opposite polarities. That is, one of each pair of voltage test points 60 is arranged on the first bus electrode 30A, and the other is arranged on the second bus electrode 30B. The voltage test point 60 arranged on the first bus electrode 30A does not contact the second collector electrode 20B, and the voltage test point 60 arranged on the second bus electrode 30B does not contact the first collector electrode 20A.

[0076] In order to reduce the series resistance effect caused by the long distance between the positive and negative test points of each pair of voltage test points 60 , a pair of voltage test points 60 is designed on two adjacent bus electrodes 30 with opposite polarities.

[0077] When the voltage test point 60 is disposed on the bus electrode 30, each voltage test point 60 and the corresponding bus electrode 30 can be formed by printing the same conductive paste at the same time. The formation of the voltage test point 60 does not require an additional printing step and will not affect the production efficiency of the solar cell.

[0078] like Figure 3 As shown, in at least one pair of voltage test points 60, the distance between the voltage test point 60 close to the first central axis Y and the first central axis is D1, and the distance between the voltage test point 60 far from the first central axis Y and the first edge of the battery substrate 10 is D2, D1<D2, and the first edge at least includes the edge portion of the battery substrate 10 extending along the second direction.

[0079] Usually, the location of the pair of open circuit voltage test points 60 on the battery substrate 10 is relatively random. In the present application, the location of the pair of open circuit voltage test points 60 eliminates the adverse effects of the PL dark areas on both side edge areas of the solar cell, and is no longer located in the middle area between the first central axis Y and the first edge of the battery substrate 10, thereby improving the stability and accuracy of the open circuit voltage test.

[0080] like Figure 3 As shown, in each pair of voltage test points 60, the center points of the two voltage test points 60 are staggered along the second direction. The positive and negative open-circuit voltage test points are staggered to prevent more collector electrodes 20 of opposite polarity from being disconnected to avoid the open-circuit voltage test points 60, thereby reducing the formation of more dead zones and increasing the short-circuit current.

[0081] like Figure 3 As shown, the two pairs of voltage test points 60 on both sides of the first central axis Y are at least partially overlapped after translation along the first direction, and the two voltage test points 60 that at least partially overlap have the same polarity. In this way, the symmetry of the test positions of the voltage test points 60 on both sides of the first central axis Y is ensured, the test accuracy is improved, and the test fixture has a repeated unit structure, which reduces the difficulty of preparing the test fixture.

[0082] Typically, a solar cell includes two halves arranged in the second direction, and the two halves are connected in series. During the open circuit voltage test, the two halves share the same cell substrate; during the subsequent photovoltaic module assembly process, the two halves are cut as needed. The two halves are connected in series, which can improve the overall power of the solar cell on the one hand, and improve the yield rate during the photovoltaic module assembly welding process on the other hand.

[0083] Figures 1 to 3In the embodiment, the battery substrate 10 of the two half-sheets includes two battery cells arranged along the second direction, and each battery cell is provided with a collector electrode 20, a bus electrode 30 and a voltage test point 60. The bus electrodes 30 provided on the two battery cells are at least partially collinear along the second direction and have opposite electrical polarities.

[0084] like Figure 3 As shown, the dividing line between the two battery cells is the second central axis X of the battery substrate 10 along the first direction. In each battery cell, at least one pair of voltage test points 60 are respectively arranged on both sides of the first central axis Y. The at least two pairs of voltage test points 60 of the two battery cells located on the same side of the first central axis Y are located on the collinear bus electrodes 30, and at least partially overlap or are symmetrically distributed relative to the second central axis X after translation along the second direction. In the two battery cells, the two voltage test points 60 on the collinear bus electrodes 30 along the second direction have opposite polarities. In this way, adjacent battery cells can be electrically connected using linear conductive connectors without any rotation of the battery cells and then interconnection, and the voltage test points 60 can also match such an electrode design. At the same time, the symmetry of the test positions of the voltage test points 60 of the two battery cells improves the test accuracy. At the same time, the test fixture has a repeated unit structure, which reduces the difficulty of preparing the test fixture.

[0085] In the two battery cells, the multiple pairs of voltage test points 60 on the battery substrate 10 are centrally symmetrical about the center point of the battery substrate 10 .

[0086] In this way, even if the battery is rotated 180 degrees, the voltage test point 60 can be completely overlapped, and there is no need to readjust the position of the open voltage test fixture, which is more suitable for large-scale mass production. In addition, the voltage test point 60 is close in each area symmetrically located in the center of the battery, and the test result is more stable.

[0087] In each battery cell, when the number of busbar electrodes 30 is an even number, the even number of busbar electrodes 30 are arranged at equal intervals, and an equal number of busbar electrodes 30 are respectively arranged on both sides of the first central axis Y. Figure 3 As shown, in each battery cell, when the number of bus electrodes 30 is an even number, then along the first direction, the number of bus electrodes 30 between the voltage test point 60 close to the first central axis Y in at least one pair of voltage test points 60 and the first central axis Y is less than the number of bus electrodes 30 between the voltage test point 60 far from the first central axis Y in at least one pair of voltage test points 60 and the first edge of the battery substrate 10.

[0088] Although not shown in the figure, in each battery cell, when the number of bus electrodes 30 is an odd number, a bus electrode 30 is also arranged at the position of the first central axis Y, and the bus electrode 30 located in the middle is collinear with the first central axis Y. The odd number of bus electrodes 30 are arranged at equal intervals. When the number of bus electrodes 30 is an odd number, along the first direction, the number of bus electrodes 30 between the voltage test point 60 close to the first central axis Y and the first central axis Y in at least one pair of voltage test points 60 (including the bus electrode 30 collinear with the first central axis Y) is equal to the number of bus electrodes 30 between the voltage test point 60 far from the first central axis Y in at least one pair of voltage test points 60 and the first edge of the battery substrate 10.

[0089] In this way, at least one pair of voltage test points 60 on both sides of the first central axis Y are basically set at the middle position along the first direction, which can improve the accuracy and stability of the open circuit voltage test and also match different numbers of bus electrodes 30.

[0090] like Figure 3 As shown, the back contact solar cell 100 further includes a plurality of interconnects 23 located on the target surface and arranged at intervals. Along the second direction, at least a portion of the plurality of interconnects 23 are collinear to form an interconnection column. The interconnects 23 include a first interconnect 23A and a second interconnect 23B with opposite polarities. Each first bus electrode 30A is collinear with a portion of the first interconnect 23A. Each second bus electrode 30B is collinear with a portion of the second interconnect 23B. The interconnect column includes a plurality of first interconnect columns and a plurality of second interconnect columns. The first interconnect column includes only the first interconnect 23A, and the second interconnect column includes only the second interconnect 23B. The first interconnect column and the second interconnect column are alternately arranged along the first direction. The plurality of first interconnects 23A of the first interconnect column are electrically connected to at least one first collector electrode 20A, and are isolated (electrically insulated) from the second collector electrode 20B. The plurality of second interconnects 23B of the second interconnect column are electrically connected to at least one second collector electrode 20B, and are isolated (electrically insulated) from the first collector electrode 20A. In the embodiment of the present application, the first bus electrode 30A completely overlaps with the first interconnection column, and the second bus electrode 30B completely overlaps with the second interconnection column.

[0091] like Figure 3 As shown, the battery substrate 10 further includes a second edge and a third edge that are spaced apart from each other, and the second edge and the third edge both include an edge portion that is at least parallel to the first direction.

[0092] like Figure 3As shown, in each battery cell, when each bus electrode 30 is colinear with an even number of interconnections 23, then along the second direction, in each pair of voltage test points 60, the number of interconnections 23 between the voltage test point 60 close to the second edge and the second edge is equal to the number of interconnections 23 between the voltage test point 60 close to the third edge and the third edge.

[0093] Although not shown in the figure, in each battery cell, when each bus electrode 30 is colinear with an odd number of interconnections 23, then along the second direction, in each pair of voltage test points 60, the number of interconnections 23 between the voltage test point 60 close to the second edge and the second edge is less than the number of interconnections 23 between the voltage test point 60 close to the third edge and the third edge.

[0094] In this way, at least one pair of voltage test points 60 on both sides of the first central axis Y is basically set at the middle position along the second direction, which can improve the accuracy and stability of the test and also match different numbers of interconnection parts 23.

[0095] like Figure 4 As shown, in a battery unit, when the number of busbar electrodes 30 located on one side of the first central axis Y is ≥ 6, at least two pairs of voltage test points 60 are provided on each side of the first central axis Y. In the at least two pairs of voltage test points 60 located on one side of the first central axis Y, different voltage test points 60 are respectively located on different busbar electrodes 30, and each voltage test point 60 in the at least two pairs of voltage test points 60 is staggered along the second direction.

[0096] In other embodiments, although not shown, in a battery cell, at least two pairs of voltage test points 60 on each side of the first central axis Y are distributed on two bus electrodes 30 with opposite polarities, and at least two pairs of open voltage test points 60 are at least partially overlapped after translation along the second direction or are symmetrically distributed relative to the second central axis of the battery cell along the first direction, so as to improve the accuracy of the test and reduce the difficulty of making the test fixture.

[0097] It can be understood that the present application is also applicable to back-contact solar cells with segmented bus electrodes. The segmented bus electrodes can be distributed at both ends of the back-contact solar cell along the second direction and electrically connected to part of the collecting electrodes 20. At least two pairs of voltage test points 60 on each side of the first central axis Y are distributed on a pair of segmented bus electrodes with opposite polarities.

[0098] As the number of busbar electrodes 30 increases, setting a pair of voltage test points 60 on one side of the first central axis Y cannot accurately reflect the actual opening voltage value. The accuracy of the test can be improved by setting two pairs of voltage test points 60. The two pairs of voltage test points 60 are staggered in the first direction and the second direction, taking into account the opening voltage test results of different positions and different numbers, thereby improving the authenticity and accuracy of the test results.

[0099] In other embodiments, the back-contact solar cell 100 only retains a portion of the main grid. In this case, although not shown, the first bus electrode 30A is located between the end of the first interconnected column and the second edge or the third edge of the battery substrate 10, and the second bus electrode 30B is located between the end of the second interconnected column and the second edge or the third edge of the battery substrate 10, that is, the first bus electrode 30A and the second bus electrode 30B are both located in the end area of ​​the battery substrate 10, thereby effectively reducing the recombination and shading losses caused by the metal electrodes.

[0100] In the present application embodiment, Figure 1 As shown, the battery substrate 10 includes two battery cells arranged along the second direction, the battery substrate 10 is a rectangle, the intersection of the first central axis Y and the second central axis X of the battery substrate 10 along the first direction is taken as the origin, the X axis is set by the second central axis X and the Y axis is set by the first central axis Y, the side length of the battery substrate along the X axis is a, and the side length along the Y axis is b, each pair of voltage test points 60 is located in a non-overlapping area between a first rectangle 40a with the origin as the center point and a second rectangle 40b with the origin as the center point, the coordinates of the vertices of the first rectangle located in the first quadrant are (a / 9, b / 9), and the coordinates of the vertices of the second rectangle located in the first quadrant are (7*a / 18, 7*b / 18).

[0101] Since the center point and one vertex of the rectangle are determined, the position of the rectangle in the coordinates can be determined. The four vertices of the first rectangle 40a are respectively located in four quadrants, and the coordinates of the four vertices are (a / 9, b / 9), (-a / 9, b / 9), (-a / 9, -b / 9) and (a / 9, -b / 9). The four vertices of the second rectangle 40b are respectively located in four quadrants, and the coordinates of the four vertices are (7*a / 18, 7*b / 18), (-7*a / 18, 7*b / 18), (-7*a / 18, -7*b / 18), (7*a / 18, -7*b / 18). The second rectangle 40b completely covers the first rectangle 40a and the area size of the second rectangle 40b is larger than the area size of the first rectangle 40a. Each pair of voltage test points 60 is located in the area where the second rectangle 40b exceeds the first rectangle 40a (the area where the two do not overlap).

[0102] By further limiting the location area of ​​the voltage test point 60 , the test accuracy and stability can be further improved.

[0103] A coordinate system of the X-axis and the Y-axis is set on the battery substrate 10, and the battery substrate 10 is divided into four equal parts (four quadrants), and at least one pair of voltage test points 60 is set in each quadrant of the coordinate system, and the open circuit voltage result measured by the pair of voltage test points 60 represents the average result of the open circuit voltage of the corresponding quadrant. In the embodiment of the present application, an example will be given in which a pair of voltage test points 60 are set in the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant, respectively. The open circuit voltage result measured by each pair of voltage test points 60 represents the average result of the open circuit voltage of the corresponding quadrant.

[0104] When the battery substrate 10 includes only one battery cell, the intersection of the first central axis and the first edge is taken as the origin, the X-axis is set along the first edge and the Y-axis is set along the first central axis Y, the side length of the battery substrate 10 along the X-axis is a, and the side length along the Y-axis is b / 2, each pair of voltage test points is located in a non-overlapping area between a first rectangle with the Y-axis as the axis of symmetry and a second rectangle with the Y-axis as the axis of symmetry, the coordinates of the vertices of the first rectangle located in the first quadrant are (a / 9, b / 9), and the coordinates of the vertices of the second rectangle located in the first quadrant are (7*a / 18, 7*b / 18).

[0105] Further, in some embodiments, please refer to Figure 2 Each pair of voltage test points 60 is located in a non-overlapping area between a third rectangle 40c with the origin as the center point and a fourth rectangle 40d with the origin as the center point, the coordinates of one of the vertices of the third rectangle 40c are (a / 6, b / 6), and the coordinates of one of the vertices of the fourth rectangle 40d are (a / 3, b / 3).

[0106] According to the coordinates of the vertices, the third rectangle 40c and the fourth rectangle 40d are both completely covered by the second rectangle 40b and the area sizes of the third rectangle 40c and the fourth rectangle 40d are both larger than the area size of the first rectangle 40a; the fourth rectangle 40d completely covers the third rectangle 40c and the area size of the fourth rectangle 40d is larger than the area size of the third rectangle 40c, then the non-overlapping area between the third rectangle 40c and the fourth rectangle 40d is located in the non-overlapping area between the first rectangle 40a and the second rectangle 40b.

[0107] Further, in some embodiments, please refer to Figure 2, a pair of voltage test points 60 in the first quadrant are located in rectangle 50a, and the coordinates of a pair of diagonal vertices of rectangle 50a are (7*a / 36, 7*b / 36) and (5*a / 18, 5*b / 18) respectively. A pair of voltage test points 60 in the second quadrant are located in rectangle 50b, and the coordinates of a pair of diagonal vertices of rectangle 50b are (-7*a / 36, 7*b / 36) and (-5*a / 18, 5*b / 18) respectively. A pair of voltage test points 60 in the third quadrant are located in rectangle 50c, and the coordinates of a pair of diagonal vertices of rectangle 50c are (-7*a / 36, -7*b / 36) and (-5*a / 18, -5*b / 18) respectively. A pair of voltage test points 60 in the fourth quadrant are located in the rectangle 50d, and the coordinates of a pair of diagonal vertices of the rectangle 50d are (7*a / 36, -7*b / 36) and (5*a / 18, -5*b / 18) respectively. Figure 2 In the figure, the position of rectangle 50a is for illustration only.

[0108] In addition, in some embodiments, the four pairs of voltage test points 60 are symmetrically arranged, and each adjacent pair of voltage test points 60 is symmetrical with respect to the X-axis or the Y-axis.

[0109] The following description will be made by taking a square battery substrate 10 (silicon wafer) as an example, with a side length a=b=180 mm. The first rectangle 40a is a square whose vertices have coordinates of (20, 20), (20, -20), (-20, -20), (-20, 20), and the second rectangle 40b is a square whose vertices have coordinates of (70, 70), (70, -70), (-70, -70), (-70, 70), and the voltage test point 60 is located in the area where the first rectangle 40a and the second rectangle 40b do not overlap, that is, the second rectangle 40b exceeds the annular area of ​​the first rectangle 40a. A pair of voltage test points 60 are respectively provided in the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant, and each pair of adjacent voltage test points 60 are symmetrically arranged relative to the X-axis or the Y-axis.

[0110] Further, the third rectangle 40c is a square whose vertices are respectively (30, 30), (30, -30), (-30, -30), (-30, 30), and the fourth rectangle 40d is a square whose vertices are respectively (60, 60), (60, -60), (-60, -60), (-60, 60), and the voltage test point 60 is located in the area where the third rectangle 40c and the fourth rectangle 40d do not overlap, that is, the fourth rectangle 40d exceeds the annular area of ​​the third rectangle 40c. A pair of voltage test points 60 is respectively provided in the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant, and each two adjacent pairs of voltage test points 60 are symmetrically provided relative to the X-axis or the Y-axis.

[0111] Furthermore, the voltage test point 60 in the first quadrant is located in a square with diagonal vertices having coordinates of (35, 35) and (50, 50); the voltage test point 60 in the second quadrant is located in a square with diagonal vertices having coordinates of (-35, 35) and (-50, 50); the voltage test point 60 in the third quadrant is located in a square with diagonal vertices having coordinates of (-35, -35) and (-50, -50); and the voltage test point 60 in the fourth quadrant is located in a square with diagonal vertices having coordinates of (35, -35) and (50, -50).

[0112] Since the position of the test probe will deviate during the test, a certain dimensional fluctuation range needs to be given to the test probe in the process of abutting the voltage test point. In the embodiment of the present application, each voltage test point 60 is set to be circular, and the radius is greater than the radius of the test probe to ensure that the test probe can completely fit the voltage test point 60. In one embodiment, the radius of the test probe is 0.25mm, and the radius of the voltage test point 60 is set to 0.5mm. On the other hand, the radius of the voltage test point 60 cannot be set too large. On the one hand, it will cause greater shading loss. On the other hand, an excessively large voltage test point 60 may contact the collector electrode 20 with the opposite polarity.

[0113] In the embodiment of the present application, 2*M>the size of each voltage test point 60 along the second direction≥0.8*M, where M is the distance between two adjacent collector electrodes 20 of the same polarity along the second direction.

[0114] The size of the voltage test point 60 is set within a specific range so that it is not too small to meet the minimum size required by the test fixture, and at the same time not too large to interrupt more collector electrodes 20 of opposite polarities, reduce the formation of more dead zones, and avoid the increase of short-circuit current.

[0115] like Figure 3 As shown, at least part of the collector electrodes 20 on the battery substrate 10 have discontinuities for spacing the bus electrodes 30 with opposite polarities. The discontinuous collector electrode 20 includes a plurality of collector electrode segments 21 spaced apart along a first direction. Both ends of the collector electrode segment 21 along the first direction are spaced apart from the bus electrodes 30 with opposite polarities.

[0116] In each solar cell, the location of the busbar electrode 30 is determined by the side length a of the solar cell 100 in the first direction and the number of busbar electrodes 30 provided. The busbar electrodes 30 are usually evenly distributed along both sides of the first direction from the center point of the cell substrate 10, and a certain length needs to be reserved for the two opposite edges of the cell substrate 10 along the first direction. The side length a in the first direction = 2 × edge reserved length + (number of busbar electrodes - 1) × spacing between two adjacent busbar electrodes.

[0117] Generally, the more busbar electrodes 30 are set, the higher the conversion efficiency of the solar cell will be. However, as the number of busbar electrodes 30 increases to a certain number, the growth rate of the solar cell conversion efficiency will gradually decrease. On the other hand, the increase of busbar electrodes 30 will increase the unit consumption of metal paste and increase the cost. If the spacing between busbar electrodes 30 is too small, it will also increase the number of solder strips and the difficulty of soldering in the later components.

[0118] The voltage test point 60 can be formed by printing when the collector electrode 20 and / or the bus electrode 30 are formed, without requiring an additional printing step and without affecting the production efficiency of the solar cell.

[0119] The electrode patterns (collecting electrodes 20, bus electrodes 30 and voltage test points 60) of the solar cell are made of a variety of conductive metal pastes, so the printing of the electrode patterns usually includes multiple overprintings of the conductive metal pastes.

[0120] In one embodiment, the electrode pattern uses three metal pastes, the N-type fine gate uses a silver paste (higher glass content), the N-type main gate uses another silver paste (lower glass content), and the P-type fine gate and P-type main gate use aluminum paste.

[0121] Silver paste is relatively more expensive, and silver paste with a higher glass content is more corrosive, which may affect the PN junction. Therefore, the voltage test point 60 uses silver paste and / or aluminum paste with a low glass content. The positive test point of a pair of voltage test points 60 (connected to the P-type fine grid or P-type main grid) uses aluminum paste, and if the negative test point of a pair of voltage test points 60 (connected to the N-type fine grid or N-type main grid) also uses aluminum paste, the contact resistance may increase due to the printing of two different pastes for the negative test point and the N-type fine grid / N-type main grid, affecting the test result of the open circuit voltage, and in order to meet the overprinting, additional material usage is required. Therefore, the negative test point of a pair of voltage test points 60 (connected to the N-type fine grid or N-type main grid) uses silver paste with a low glass content, and the positive test point (connected to the P-type fine grid or P-type main grid) uses aluminum paste.

[0122] The present application also provides a photovoltaic module including at least one of the above-mentioned solar cells 100, for example, including at least two of the above-mentioned solar cells 100 spliced ​​to each other. The photovoltaic module also includes a conductive interconnection member, which is electrically connected to the bus electrode.

[0123] The present application sets a voltage test point 60 at a specific position on the battery substrate 10 to avoid the influence of the PL dark area on the battery on the test results, thereby improving the stability and accuracy of the open circuit voltage test, while also avoiding the problem of designing too many voltage test points that leads to increased shading loss, reduced fine grid area, and increased silver paste loss.

[0124] The above implementation modes are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred implementation modes, a person skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A back contact solar cell, characterized in that: include: a battery substrate, the battery substrate comprising a first surface and a second surface opposite to each other, wherein one of the first surface and the second surface is a target surface; a plurality of collector electrodes, located on the target surface, the plurality of collector electrodes extending along a first direction, the plurality of collector electrodes comprising a first collector electrode and a second collector electrode with opposite polarities, at least a portion of the first collector electrodes and at least a portion of the second collector electrodes being alternately arranged along a second direction, the first direction being different from the second direction; a plurality of bus electrodes, located on the target surface, each of the bus electrodes extending along the second direction, the plurality of bus electrodes comprising a plurality of first bus electrodes and a plurality of second bus electrodes with opposite polarities, the plurality of first bus electrodes and the plurality of second bus electrodes being arranged at intervals along the first direction, the first bus electrodes being electrically connected to at least a portion of the first collector electrodes, and the second bus electrodes being electrically connected to at least a portion of the second collector electrodes; At least one pair of voltage test points are respectively arranged on both sides of the first central axis of the battery substrate, the first central axis extends along the second direction, and the at least one pair of voltage test points are respectively located on a pair of the first bus electrode and the second bus electrode; Among the at least one pair of voltage test points, the distance between the voltage test point close to the first central axis and the first central axis is D1, and the distance between the voltage test point far from the first central axis and the first edge of the battery substrate is D2, D1<D2, and the first edge includes the edge portion of the battery substrate extending along the second direction.

2. The back contact solar cell according to claim 1, characterized in that: In the at least one pair of voltage test points, center points of the two voltage test points are staggered from each other along the second direction, and / or, The two pairs of voltage test points located on both sides of the first central axis at least partially overlap after being translated along the first direction, and the two voltage test points that at least partially overlap have the same polarity.

3. The back contact solar cell according to claim 1, characterized in that: When the number of the busbar electrodes is an odd number, along the first direction, the number of busbar electrodes between the voltage test point close to the first central axis in the at least one pair of voltage test points and the first central axis is equal to the number of busbar electrodes between the voltage test point far from the first central axis in the at least one pair of voltage test points and the first edge of the battery substrate; When the number of bus electrodes is an even number, then along the first direction, the number of bus electrodes between the voltage test point close to the first central axis in the at least one pair of voltage test points and the first central axis is less than the number of bus electrodes between the voltage test point away from the first central axis in the at least one pair of voltage test points and the first edge of the battery substrate.

4. The back contact solar cell according to claim 1, characterized in that: The battery substrate further includes a second edge and a third edge that are relatively spaced apart, the second edge and the third edge each include an edge portion that is at least parallel to the first direction, the battery substrate further includes a plurality of interconnecting portions that are spaced apart, and each of the bus electrodes is collinear with at least a portion of the interconnecting portions; When the number of interconnections collinear with each of the bus electrodes is an odd number, then along the second direction, in each pair of the voltage test points, the number of interconnections between the voltage test point close to the second edge and the second edge is less than the number of interconnections between the voltage test point close to the third edge and the third edge; When the number of the interconnections co-linear with each of the bus electrodes is an even number, then along the second direction, in each pair of the voltage test points, the number of interconnections between the voltage test points close to the second edge and the second edge is equal to the number of interconnections between the voltage test points close to the third edge and the third edge.

5. The back contact solar cell according to claim 1, characterized in that: When the number of busbar electrodes located on one side of the first central axis is ≥6, at least two pairs of voltage test points are arranged on each side of the first central axis.

6. The back contact solar cell according to claim 5, characterized in that: At least two pairs of voltage test points are arranged on each side of the first central axis, wherein different voltage test points are respectively located on different bus electrodes, and the at least two pairs of voltage test points are staggered along the second direction.

7. The back contact solar cell according to claim 5, characterized in that: At least two pairs of voltage test points are arranged on each side of the first central axis, and the at least two pairs of voltage test points at least partially overlap after translation along the second direction or are symmetrically distributed relative to the second central axis of the battery substrate along the first direction.

8. The back contact solar cell according to claim 1, characterized in that: 2*M>the size of each voltage test point along the second direction ≥0.8*M, wherein M is the distance between two adjacent collector electrodes of the same polarity along the second direction.

9. The back contact solar cell according to claim 1, characterized in that: The intersection of the first central axis and the first edge is taken as the origin, the X-axis is set by the first edge and the Y-axis is set by the first central axis, the side length of the battery base along the X-axis is a, and the side length along the Y-axis is b / 2, each pair of voltage test points is located in a non-overlapping area between a first rectangle with the Y-axis as the axis of symmetry and a second rectangle with the Y-axis as the axis of symmetry, the coordinates of the vertices of the first rectangle located in the first quadrant are (a / 9, b / 9), and the coordinates of the vertices of the second rectangle located in the first quadrant are (7*a / 18, 7*b / 18).

10. A back contact solar cell, characterized in that: include: a battery substrate comprising a first surface and a second surface opposite to each other, wherein one of the first surface and the second surface is a target surface; The battery substrate includes two battery cells arranged along a second direction, each of the battery cells including: a plurality of collector electrodes, located on the target surface, the plurality of collector electrodes extending along a first direction, the plurality of collector electrodes comprising a first collector electrode and a second collector electrode with opposite polarities, at least a portion of the first collector electrodes and at least a portion of the second collector electrodes being alternately arranged along a second direction, the first direction being different from the second direction; a plurality of bus electrodes, located on the target surface, each of the bus electrodes extending along the second direction, the bus electrodes comprising a plurality of first bus electrodes and a plurality of second bus electrodes with opposite polarities, the plurality of first bus electrodes and the plurality of second bus electrodes being arranged at intervals along the first direction, the first bus electrodes being electrically connected to at least a portion of the first collector electrodes, and the second bus electrodes being electrically connected to at least a portion of the second collector electrodes; At least one pair of voltage test points are respectively arranged on both sides of the first central axis of each of the battery cells, the first central axis extends along the second direction, and the at least one pair of voltage test points are respectively located on an adjacent pair of the first bus electrode and the second bus electrode; Among the at least one pair of voltage test points, the distance between the voltage test point close to the first central axis and the first central axis is D1, and the distance between the voltage test point far from the first central axis and the first edge of the battery substrate is D2, D1<D2, and the first edge includes the edge portion of the battery substrate extending along the second direction.

11. The back contact solar cell according to claim 10, characterized in that: The bus electrodes provided on the two battery cells are at least partially collinear along the second direction and have opposite polarities, and at least two pairs of voltage test points of the two battery cells located on the same side of the first central axis at least partially overlap after translation along the second direction or are symmetrically distributed relative to the second central axis of the battery base along the first direction.

12. The back contact solar cell according to claim 10, characterized in that: In the at least one pair of voltage test points, center points of the two voltage test points are staggered from each other along the second direction, and / or, In the same battery unit, two pairs of voltage test points located on both sides of the first central axis at least partially overlap after translation along the first direction, and the two voltage test points that at least partially overlap have the same polarity, and / or, The multiple pairs of voltage test points on the battery substrate are centrally symmetric with respect to the center point of the battery substrate, and / or, in two battery cells, two voltage test points on the bus electrodes that are collinear along the second direction have opposite polarities.

13. The back contact solar cell according to claim 10, characterized in that: The intersection of the first central axis and the second central axis of the battery substrate along the first direction is taken as the origin, the X-axis is set by the second central axis and the Y-axis is set by the first central axis, the side length of the battery substrate along the X-axis is a, and the side length along the Y-axis is b, each pair of voltage test points is located in a non-overlapping area between a first rectangle with the origin as the center point and a second rectangle with the origin as the center point, the coordinates of the vertices of the first rectangle located in the first quadrant are (a / 9, b / 9), and the coordinates of the vertices of the second rectangle located in the first quadrant are (7*a / 18, 7*b / 18).

14. A photovoltaic module, characterized in that: The invention comprises at least one back-contact solar cell according to any one of claims 1 to 13 and a conductive interconnection electrically connecting the bus electrode.

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