Back-contact solar cells and photovoltaic modules

Abstract

The present invention provides a back-contact solar cell and a photovoltaic module, and relates to the field of photovoltaic technology. The back-contact solar cell includes: a battery body and an electrode structure; the electrode structure includes: a plurality of collector grid lines extending along the second direction; a plurality of electrical connection parts electrically connected to the collector grid lines; the electrical connection parts electrically connected to the collector grid lines of the same polarity include: an edge electrical connection part close to the edge of the first battery; on the same side in the second direction, the distance between the end of the collector grid line and the geometric center of the edge electrical connection part electrically connected thereto is D1; ​​in the second direction, the spacing between the geometric centers of adjacent electrical connection parts electrically connected to the collector grid lines of the same polarity is D2; for at least one collector grid line of polarity, D2>1.5×D1, D2<3×D1. The present application avoids the performance loss caused by long-distance carrier or current transmission at the location of the edge electrical connection part, and maximizes the collection and conduction of carriers or current.

Description

Technical Field

[0001] The invention relates to the field of photovoltaic technology, in particular to a back-contact solar cell and a photovoltaic module. Background Art

[0002] Back-contact solar cells can make full use of sunlight and increase their short-circuit current because of their structure without grid lines on the light-facing side. At the same time, because the grid lines are located on the backlight side, a wider grid line structure can be set to reduce the series resistance and thus improve the fill factor, and it has higher efficiency. In addition, back-contact solar cells look more beautiful and are easier to assemble into mass-produced photovoltaic modules, so they have a wide range of application scenarios.

[0003] The electrode structure of the back contact solar cell is used to collect and conduct current. However, the electrode structure of the existing back contact solar cell is not good at collecting carriers or current at the edge of the cell, which affects the performance of the back contact solar cell. Summary of the invention

[0004] The present invention provides a back-contact solar cell and a photovoltaic module, aiming to solve the problem of poor carrier or current collection at the edge of the cell in the existing back-contact solar cell.

[0005] A first aspect of the present invention provides a back-contact solar cell, comprising:

[0006] A battery body and an electrode structure located on one side of the battery body; the battery body includes a first battery edge, the first battery edge at least has a portion parallel to a first direction; the electrode structure includes:

[0007] A plurality of collector grid lines extending along a second direction; the collector grid lines with different polarities are spaced and alternately distributed along the first direction; the first direction is different from the second direction;

[0008] A plurality of electrical connection parts electrically connected to the collector grid lines; the electrical connection parts electrically connected to the collector grid lines of the same polarity include: an edge electrical connection part close to the edge of the first battery;

[0009] On the same side in the second direction, the distance between the end of the collector grid line and the geometric center of the edge electrical connection portion electrically connected thereto is D1; ​​in the second direction, the distance between the geometric centers of adjacent electrical connection portions electrically connected to the collector grid line of the same polarity is D2;

[0010] For the collector grid line of at least one polarity, D2>1.5×D1, D2<3×D1.

[0011] In the present application, for at least one polarity of the collector grid line, D2>1.5×D1, D2<3×D1, the difference between the current collection range of the edge electrical connection part close to the edge of the first battery and the current collection range of the remaining electrical connection parts is minimized as much as possible, and then for the collector grid line of the same polarity, the current or carrier collection range or collection distance of the edge electrical connection part is smaller than the current or carrier collection range or collection distance of the remaining electrical connection parts. Both the edge electrical connection part and the remaining electrical connection parts roughly divide the collection and conduction of current or carriers at the same distance of the collector grid line, avoiding performance loss caused by long-distance carrier or current transmission at the edge electrical connection part, and can maximize the collection and conduction of carriers or current, thereby improving the efficiency of the back-contact solar cell.

[0012] Optionally, on the same side in the second direction, the distance between geometric centers of edge electrical connection portions respectively corresponding to the collector grid lines of two polarities in the second direction is D3;

[0013] The dimension of the battery body in the second direction is X;

[0014] In the second direction, the number of the electrical connection parts electrically connected to the collector grid lines of the same polarity is Y;

[0015] D3≤X / (4Y).

[0016] Optionally, on the same side in the second direction, the distance between geometric centers of edge electrical connection portions respectively corresponding to the collector grid lines of two polarities in the second direction is D3;

[0017] For the collector grid line of at least one polarity, D2>1.5×D1, D2<3×D1, and D3 is less than or equal to (1 / 2) of D1.

[0018] Optionally, the collector grid lines with the same polarity are distributed evenly along the second direction, and the collector grid lines with different polarities are distributed staggered along the second direction, and the staggered distance between the ends of the collector grid lines along the second direction is D4;

[0019] On the same side in the second direction, the distance between the geometric centers of the edge electrical connection parts respectively corresponding to the collector grid lines of two polarities in the second direction is D3;

[0020] Where D3 = D4;

[0021] For the collector grid lines of two polarities, D2>1.5×D1 and D2<3×D1 are satisfied.

[0022] Optionally, on the same side in the second direction, the distance between geometric centers of edge electrical connection portions respectively corresponding to the collector grid lines of two polarities in the second direction is D3;

[0023] The dimension of the battery body in the second direction is X;

[0024] In the second direction, the number of the electrical connection parts electrically connected to the collector grid lines of the same polarity is Y;

[0025] D3≤(X / Y-1300μm).

[0026] Optionally, 1300μm≤D3≤1400μm.

[0027] Optionally, on the same side in the second direction, the distance between geometric centers of edge electrical connection portions respectively corresponding to the collector grid lines of two polarities in the second direction is D3;

[0028] D3≤D2.

[0029] Optionally, the electrode structure further includes:

[0030] The connecting grid line is located between the edge of the first battery and the collector grid line. On the same side in the second direction, the connecting grid line electrically connects a plurality of the collector grid lines of the same polarity.

[0031] Optionally, the electrode structure further comprises: a plurality of busbar lines extending along the first direction; busbar lines of different polarities are alternately and spaced apart along the second direction; the collector lines are electrically connected to busbar lines of the same polarity and electrically isolated from busbar lines of opposite polarity; in the first direction, the busbar lines are intermittently arranged;

[0032] The electrical connection portion includes: a plurality of first electrical connection portions electrically connected to the collector grid lines, and a plurality of second electrical connection portions electrically connected to the bus grid lines.

[0033] Optionally, the electrode structure further comprises: a plurality of busbar lines extending along the first direction; busbar lines of different polarities are alternately and spaced apart along the second direction; the collector lines are electrically connected to the busbar lines of the same polarity and electrically isolated from the collector lines of the opposite polarity; in the first direction, the busbar lines are continuously arranged;

[0034] The electrical connection portion includes: a plurality of second electrical connection portions electrically connected to the busbar lines.

[0035] Optionally, for the collector grid line of at least one polarity, D1 = (1 / 2) × D2.

[0036] A second aspect of the present invention provides a photovoltaic module, comprising: a plurality of cell strings, wherein the cell strings include a plurality of any of the aforementioned back-contact solar cells.

[0037] The above-mentioned back-contact solar cells and photovoltaic systems have the same or similar beneficial effects, and will not be described again here to avoid repetition. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0039] Figures 1 to 3 Partial schematic diagrams of three types of back-contact solar cells in embodiments of the present invention are shown.

[0040] Description of the accompanying drawings:

[0041] 1-battery body, 11-first battery edge, 21-collecting grid line, 211-first polarity collecting grid line, 212-second polarity collecting grid line, 22-electrical connection part, 221-first polarity electrical connection part, 222-second polarity electrical connection part, 23-connecting grid line. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The present invention provides a back contact solar cell. Figures 1 to 3 In order to distinguish the collector grid lines of different polarities, the colors of the collector grid lines 21 of different polarities are set to black and red, respectively. At the same time, the electrical connection parts 22 connected to the collector grid lines 21 of different polarities are distinguished by red and black. Figure 1 and Figure 2 In the figure, the dimension markings D1 to D4 are only used for the purpose of unified description. The same dimension markings at different positions may be equal or unequal in size.

[0044] Reference Figure 1 , Figure 2 and Figure 3The back-contact solar cell includes: a cell body 1 and an electrode structure located on one side of the cell body 1. During normal operation of the back-contact solar cell, the side of the cell body that mainly absorbs light is the light-facing side, the light-facing side is opposite to the backlight side, and the electrode structure is located on the backlight side. The cell body contains a PN junction that can separate carriers. The cell body 1 includes a first cell edge 11, and the first cell edge 11 has at least a portion parallel to the first direction L1. Figures 1 to 3 In the figure, the first direction L1 is the vertical direction. In the case where the battery body has a chamfer, the rest of the first battery edge 11 except the chamfer is parallel to the first direction L1. For example, referring to Figures 1 to 3 In the case where the battery body does not have a chamfer, the first battery edge 11 is substantially parallel to the first direction L1. Figures 1 to 3 When the battery body is substantially rectangular, one battery body includes two first battery edges 11 .

[0045] The electrode structure includes: a plurality of collector grid lines 21 extending along the second direction L2. The collector grid lines 21 with different polarities are spaced and alternately distributed along the first direction L1, and the collector grid lines 21 with different polarities include: a first polarity collector grid line 211 and a second polarity collector grid line 212, one of the first polarity collector grid line 211 and the second polarity collector grid line 212 is an N-type collector grid line, and the other is a P-type collector grid line. Figures 1 to 3 In the figure, the second polarity collector grid line 212 is indicated by the red collector grid line, and the first polarity collector grid line 211 is indicated by the black collector grid line. The interval here can avoid short circuit, and the alternation here means that in the first direction L1, an N-type collector grid line is followed by a P-type collector grid line and then an N-type collector grid line. The first direction L1 is different from the second direction L2, and the angle between the two is not limited, for example, they can be perpendicular or nearly perpendicular to each other.

[0046] The electrode structure may also include: a plurality of electrical connection portions 22 electrically connected to the collector grid lines 21. The electrical connection portions 22 include a first polarity electrical connection portion 221 electrically connected to the first polarity collector grid line 211, and a second polarity electrical connection portion 222 electrically connected to the second polarity collector grid line 212. The electrical connection portions 22 electrically connected to the collector grid lines 21 of the same polarity include: an edge electrical connection portion close to the first battery edge 11. Specifically, the electrical connection portions 22 electrically connected to the N-type collector grid lines 21 include: an edge electrical connection portion close to the first battery edge 11, and the electrical connection portions 22 electrically connected to the P-type collector grid lines 21 include: an edge electrical connection portion close to the first battery edge 11. For example, Figure 1In the figure, the second polarity collector grid line 212 represented by the red collector grid line and the first polarity collector grid line 211 represented by the black collector grid line represent collector grid lines of two polarities respectively, and the edge electrical connection portion in the first polarity electrical connection portion 221 electrically connected to the first polarity collector grid line 211 is the leftmost first polarity electrical connection portion 221 in the first polarity electrical connection portion 221 electrically connected to the first polarity collector grid line 211, and the rightmost first polarity electrical connection portion 221 in the first polarity electrical connection portion 221 electrically connected to the first polarity collector grid line 211; the edge electrical connection portion in the second polarity electrical connection portion 222 electrically connected to the second polarity collector grid line 212 is the leftmost second polarity electrical connection portion 222 in the second polarity electrical connection portion 222 electrically connected to the second polarity collector grid line 212, and the rightmost second polarity electrical connection portion 222 in the second polarity electrical connection portion 222 electrically connected to the second polarity collector grid line 212. Among them, on the far left, the edge electrical connection portion 22 electrically connected to the first polarity collector grid line 211 is located on the outside of the edge electrical connection portion 22 electrically connected to the second polarity collector grid line 212, and on the far right, the edge electrical connection portion 22 electrically connected to the second polarity collector grid line 212 is located on the outside of the edge electrical connection portion 22 electrically connected to the first polarity collector grid line 211.

[0047] It should be noted that the number of edge electrical connection portions electrically connected to the collector gate lines 21 of the same polarity is usually greater than or equal to 1. When the number of edge electrical connection portions is greater than 1, on the same side in the second direction L2, the edge electrical connection portions electrically connected to the collector gate lines 21 of the same polarity are usually at least partially collinear.

[0048] On the same side in the second direction L2, the distance between the end of the collector grid line 21 and the geometric center of the electrical connection portion with the electrical connection edge thereof is D1. It should be noted that the distance between the end of the collector grid line 21 and the geometric center of the electrical connection portion with the electrical connection edge thereof refers to the end of the current transmission path of the collector grid line connected to the electrical connection portion. For example, Figure 1 and Figure 2 In the figure, the second direction L2 is the left-right direction, and on the left side of the second direction L2, the distance between the end of the N-type collector grid line and the geometric center of the electrical connection portion with its electrical connection edge is D1; ​​or, on the left side of the second direction L2, the distance between the end of the P-type collector grid line 21 and the geometric center of the electrical connection portion with its electrical connection edge is D1; ​​on the right side of the second direction L2, the distance between the end of the N-type collector grid line and the geometric center of the electrical connection portion with its electrical connection edge is D1; ​​or, on the right side of the second direction L2, the distance between the end of the P-type collector grid line 21 and the geometric center of the electrical connection portion with its electrical connection edge is D1. Figure 1 and Figure 2In the figure, only the first polarity collector grid line 211 is taken as an example to illustrate the relevant dimensions, and the relevant dimension markings of the second polarity collector grid line 212 are similar to this.

[0049] It should be noted that Figure 1 and Figure 2 In the figure, the black dotted line is a schematic diagram passing through the geometric center of the first polarity electrical connection portion 221 electrically connected to the first polarity collector grid line 211 and parallel to the first direction L1, and the red dotted line is a schematic diagram passing through the geometric center of the second polarity electrical connection portion 222 electrically connected to the second polarity collector grid line 212 and parallel to the first direction L1. The above red dotted lines and black dotted lines are only used for distinction.

[0050] In the second direction L2, the spacing between the geometric centers of adjacent electrical connection parts 22 electrically connected to the collector grid lines 21 of the same polarity is D2, that is, in the second direction L2, the spacing between the geometric centers of adjacent electrical connection parts 22 electrically connected to the N-type collector grid lines 21 is D2, and in the second direction L2, the spacing between the geometric centers of adjacent electrical connection parts 22 electrically connected to the P-type collector grid lines 21 is D2. For the N-type collector grid lines 21 and the P-type collector grid lines 21, the corresponding D2 may be equal or unequal, and there is no specific limitation on this. For example, Figure 1 and Figure 2 In the figure, the corresponding D2 of the N-type collector gate line 21 and the P-type collector gate line 21 are equal.

[0051] In the existing back-contact solar cells, in the second direction L2, for the collector grid lines of the same polarity, D1=D2 here, that is, for the collector grid lines of the same polarity, the current collection range of the edge electrical connection portion close to the edge of the first battery is roughly twice the current collection range of the remaining electrical connection portions, and the current collection range of the edge electrical connection portion is significantly larger than the current collection range of the remaining electrical connection portions, and thus the transmission distance of part of the current or carriers transmitted to the edge electrical connection portion is longer. Due to the existence of the line resistance of the collector grid line itself, during the transmission process over a longer transmission distance, it is easy to cause the carriers or current on the collector grid line electrically connected to the edge electrical connection portion to be consumed with a high probability if not collected on the edge electrical connection portion, thereby affecting the overall battery performance.

[0052] Based on the above technical problems, in the present application, for at least one polarity of the collector grid line 21, the relationship D2>1.5×D1, D2<3×D1 is satisfied, and the difference between the current collection range of the edge electrical connection part close to the edge of the first battery and the current collection range of the other electrical connection parts is minimized as much as possible. Furthermore, for the collector grid lines of the same polarity, the current or carrier collection range or collection distance of the edge electrical connection part is smaller than the current or carrier collection range or collection distance of the other electrical connection parts. Both the edge electrical connection part and the other electrical connection parts roughly divide the collection and conduction of current or carriers at the same distance of the collector grid line, avoiding performance loss caused by long-distance carrier or current transmission at the edge electrical connection part, and maximizing the collection and conduction of carriers or current, thereby improving the efficiency of the back-contact solar cell.

[0053] It should be noted that the above relationship may be applicable to both collector gate lines of two polarities, or only to collector gate lines of one polarity. In the case where the above relationship is applicable to only collector gate lines of one polarity, the collector gate line of this polarity may be an N-type collector gate line or a P-type collector gate line, and no specific limitation is made to this.

[0054] The electrical connection portion 22 here can be a thickened section of the collector grid line itself, or a separately provided electrical connection portion. In the case where the electrical connection portion 22 is a thickened section of the collector grid line itself, the line width of the remaining part of the collector grid line is smaller than the line width of the electrical connection portion 22. A separately provided electrical connection portion can connect one collector grid line or multiple collector grid lines of the same polarity, and the multiple can be two, three or all the same collector grid lines along the first direction. The electrical connection portion includes a pad or a busbar.

[0055] For example, for at least one polarity of the collector grid line, D2 can be 1.52×D1, 1.6×D1, 1.7×D1, 1.8×D1, 1.9×D1, 2×D1, 2.1×D1, 2.2×D1, 2.3×D1, 2.4×D1, 2.5×D1, 2.6×D1, 2.7×D1, 2.8×D1, 2.9×D1, and 2.98×D1.

[0056] Optionally, in the present application, for at least one polarity of the collector grid line 21, D1 = (1 / 2) × D2, and the difference between the current collection range of the edge electrical connection portion close to the edge of the first battery and the current collection range of the remaining electrical connection portions is smaller, and thus for the collector grid lines of the same polarity, the current or carrier collection range or collection distance of the edge electrical connection portion is made substantially equal to the current or carrier collection range or collection distance of the remaining electrical connection portions, and both the edge electrical connection portion and the remaining electrical connection portion substantially divide the collection and conduction of the current or carriers at the same distance of the collector grid line, thereby avoiding performance losses caused by long-distance carrier or current transmission at the edge electrical connection portion, and maximizing the collection and conduction of carriers or current, thereby improving the efficiency of the back-contact solar cell.

[0057] Optional, see Figure 1 , for at least one polarity of the collector grid line 21, the relationship D2>1.5×D1, D2<3×D1 is satisfied, for example, Figure 1 In the figure, only the first polarity collector grid line 211 represented by black satisfies the relationship, and the second polarity collector grid line 212 represented by red does not satisfy the relationship; the collector grid lines 21 with different polarities are arranged in parallel along the second direction L2, that is, the first polarity collector grid line 211 and the second polarity collector grid line 212 are arranged in parallel along the second direction L2; the collector grid lines 21 with the same polarity are usually also arranged in parallel along the second direction L2, which means that the N-type collector grid line and the P-type collector grid line are arranged in parallel along the second direction L2. Here, only the collector grid line 21 of one polarity, that is, only the first polarity collector grid line 211 represented by black satisfies the relationship D2>1.5×D1, D2<3×D1, which means that in the back-contact solar cell, only the N-type collector grid line satisfies the relationship D2>1.5×D1, D2<3×D1, or, in the back-contact solar cell, only the P-type collector grid line satisfies the relationship D2>1.5×D1, D2<3×D1. The collector grid line 21 is usually in electrical contact with the corresponding doping layer below, and the collector grid lines 21 of different polarities are distributed flush along the second direction L2. In the alignment process, the alignment process of the doping layers and collector grid lines of different polarities is the same or similar, and the alignment process is simple, which can reduce the difficulty of the process and improve the yield.

[0058] Optional, see Figure 1, for at least one polarity of the collector grid line 21, D2>1.5×D1, D2<3×D1, on the same side in the second direction L2, the geometric centers of the edge electrical connection parts corresponding to the collector grid lines 21 of the two polarities are spaced apart in the second direction L2 by D3, that is, on the same side in the second direction L2, the geometric centers of the edge electrical connection parts corresponding to the N-type collector grid line and the geometric centers of the edge electrical connection parts corresponding to the P-type collector grid line are spaced apart in the second direction L2 by D3. The size of the battery body 1 in the second direction L2 is X. In the second direction L2, the number of electrical connection parts 22 electrically connected to the collector grid line 21 of the same polarity is Y, where Y is a natural number. For example, Figure 1 In the second direction L2, the number of electrical connection parts 22 electrically connected to the collector grid lines 21 of the same polarity is 5. In the present application, D3≤X / (4Y). Specifically, if D3 is too large, that is, the distance between the geometric centers of the edge electrical connection parts corresponding to the collector grid lines of two polarities on the same side of the second direction L2 is too large in the second direction L2, when Y is constant, the collector grid line of one polarity (such as Figure 1 The edge electrical connection part of one side (such as the left side) electrically connected to the red collector grid line in the middle is too close to the inside, and the carrier or current collection distance close to the edge of the first battery is long. In a long transmission distance, it is easy to cause the carrier or current on the collector grid line electrically connected to the edge electrical connection part to be consumed before being collected on the edge electrical connection part. At the same time, the collector grid line of this polarity (such as Figure 1 The electrical connection portion of the edge of one side (such as the right side) of the electrical connection of the red collector grid line in the middle is further outward, which will introduce more hidden crack risks near the edge of the first battery of the back contact battery during welding and lamination. Therefore, in this application, D3, X and Y are established as above. Through this association definition, it is ensured that D3 is not too large for battery bodies of various sizes and the number of electrical connections. On the one hand, the collector grid line of one polarity (such as Figure 1 The carrier or current collection distance of one side (such as the left side) of the electrical connection of the red collector grid line in the middle close to the edge of the first battery is not too large, so that the current or carrier collection range or collection distance of the edge electrical connection part is as close as possible to the current or carrier collection range or collection distance of the other electrical connections, which can avoid the performance loss caused by long-distance carrier or current transmission at the location of the edge electrical connection as much as possible, and realize effective carrier collection; secondly, the collector grid line of this polarity (such as Figure 1 The edge electrical connection portion of one side (such as the right side) of the electrical connection of the red collector grid line is not too far outward, reducing the risk of hidden cracks.

[0059] For example, for the collector grid line 21 of at least one polarity, D2>1.5×D1, D2<3×D1, and D3 can be X / (4Y), X / (5Y), X / (12Y), X / (6Y), X / (7Y), X / (8Y), X / (9Y), X / (10Y), X / (11Y), and X / (15Y).

[0060] In the present application, the specific size of the dimension X of the battery body 1 in the second direction L2 is not limited. For example, X can be 156mm (millimeter), 156mm, 158mm, 160mm, 163mm, 170mm, 178mm, 180mm, 185mm, 190mm, 195mm, 200mm, 205mm, 207mm, 210mm. The value of X here is more compatible with the size of the existing silicon substrate, and is convenient for packaging and transportation. In the second direction L2, the size of the number Y of electrical connection parts 22 electrically connected to the collector grid line 21 of the same polarity is not limited. For example, in the second direction L2, the number Y of electrical connection parts 22 electrically connected to the collector grid line 21 of the same polarity can be 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24. In a photovoltaic module, in a back-contact solar cell, in the second direction L2, increasing the number Y of electrical connection parts 22 electrically connected to the collector grid lines 21 of the same polarity has a lower limit on the effect of reducing power transmission loss. In the second direction L2, the curve of the number Y of electrical connection parts 22 electrically connected to the collector grid lines 21 of the same polarity and the power transmission loss is similar to a U-shaped curve with an opening facing upwards. When the power transmission loss is the smallest, Y is 12 to 30; at the same time, in a back-contact solar cell, when Y increases to a certain extent, the efficiency of the back-contact solar cell gradually tends to be flat, and further increase will lead to an increase in the wet weight of the electrode slurry. In summary, the number Y of electrical connection parts 22 electrically connected to the collector grid lines 21 of the same polarity in a back-contact solar cell can be 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, which is the result of a balance of multiple factors such as power transmission loss, efficiency, and wet weight of electrode slurry.

[0061] Optional, see Figure 1, for at least one collector grid line 21 (black collector grid line) of polarity satisfying D2>1.5×D1, D2<3×D1, on the same side of the second direction L2, the distance between the geometric centers of the edge electrical connection parts corresponding to the collector grid lines 21 of the two polarities in the second direction L2 is D3. For the definition of D3, refer to the above record. In order to avoid repetition, it will not be repeated here. D3 is less than or equal to the collector grid line satisfying D2>1.5×D1, D2<3×D1, for example, (1 / 2) of D1 corresponding to the black collector grid line, that is, D3 cannot be greater than (1 / 2) of the distance D1 between the end of the black collector grid line satisfying D2>1.5×D1, D2<3×D1 and the geometric center of the edge electrical connection part electrically connected to it. Specifically, D3 is not too large. On the first hand, the collector grid line of the other polarity (such as Figure 1 The carrier or current collection distance of one side (such as the left side) electrically connected to the first battery edge is not too large, so that effective carrier collection can be achieved; secondly, the collector grid line of another polarity (such as Figure 1 The electrical connection of the red collector grid line on one side (such as the right side) is not too far outward, reducing the risk of hidden cracks. Figure 1 In the example, D3 is less than or equal to (1 / 2) of D1 corresponding to the black collector grid line satisfying D2>1.5×D1, D2<3×D1. D3 can be 1 / 2, 1 / 3, 1 / 4, 1 / 5, 1 / 6, 1 / 7, 1 / 8, 1 / 9, 1 / 10 of D1 corresponding to the black collector grid line satisfying D2>1.5×D1, D2<3×D1.

[0062] Optional, see Figure 1 , for at least one polarity collector grid line 21 that satisfies D2>1.5×D1, D2<3×D1, on the same side of the second direction L2, the geometric centers of the edge electrical connection parts corresponding to the two polarity collector grid lines 21 are spaced apart in the second direction L2 by D3. For the definition of D3, refer to the above description. In order to avoid repetition, it will not be repeated here. In the present application, D3≤D2, D3 is not too large. In the first aspect, the collector grid line of another polarity that does not satisfy D2>1.5×D1, D2<3×D1 (such as Figure 1 The distance of the carrier or current collection on the side (such as the left side) electrically connected to the edge of the first battery is not too large, so that effective carrier collection can be achieved; secondly, the collector grid line of another polarity (such as the red collector grid line in the middle) that does not meet D2>1.5×D1, D2<3×D1 Figure 1 The edge electrical connection portion of one side (such as the right side) of the electrical connection of the red collector grid line is not too far outward, reducing the risk of hidden cracks.

[0063] For example, for the collector grid line 21 of at least one polarity, D2>1.5×D1, D2<3×D1, and D3 can be D2, D2×(1 / 10), D2×(1 / 9), D2×(1 / 8), D2×(1 / 7), D2×(1 / 6), D2×(1 / 5), D2×(1 / 4), D2×(1 / 3), D2×(1 / 2), D2×(3 / 5), D2×(2 / 5).

[0064] Optional, see Figure 2 For the collector gate lines of both polarities, D2>1.5×D1 and D2<3×D1 are satisfied, that is, for the N-type collector gate line, on the same side in the second direction L2, the distance between the end of the N-type collector gate line and the geometric center of the electrical connection part with its electrically connected edge is D1; ​​in the second direction L2, the spacing between the geometric centers of the adjacent electrical connection parts electrically connected to the N-type collector gate line is D2, D2>1.5×D1, D2<3×D1; for the P-type collector gate line, on the same side in the second direction L2, the distance between the end of the P-type collector gate line and the geometric center of the electrical connection part with its electrically connected edge is D1; ​​in the second direction L2, the spacing between the geometric centers of the adjacent electrical connection parts electrically connected to the P-type collector gate line is D2, D2>1.5×D1, D2<3×D1. N-type collector grid lines and P-type collector grid lines with different polarities are staggered along the second direction L2, P-type collector grid lines with the same polarity are aligned along the second direction L2, and N-type collector grid lines with the same polarity are aligned along the second direction L2. By arranging the N-type collector grid lines and P-type collector grid lines with different polarities to be staggered along the second direction L2, two types of collector grid lines with polarities are realized, so that the current or carrier collection range or collection distance of the edge electrical connection part is roughly equal to or has a small difference with the current or carrier collection range or collection distance of the remaining electrical connections. Both the edge electrical connection part and the remaining electrical connection part roughly divide the collection and conduction of the current or carriers at the same distance of the collector grid lines, avoiding the performance loss caused by long-distance carrier or current transmission at the edge electrical connection part, and can maximize the collection and conduction of carriers or current, thereby improving the efficiency of the back-contact solar cell. At the same time, the collector gate line 21 is usually in electrical contact with the corresponding doped layer below, and the collector gate lines 21 with the same polarity are distributed flush along the second direction L2. During the alignment process, the alignment processes of the doped layers and collector gate lines with the same polarity are the same or similar. The alignment process is relatively simple, which can reduce process risks and improve yields.

[0065] Optional, see Figure 3, for the two polarity collector grid lines, both satisfy D2>1.5×D1, D2<3×D1, the collector grid lines of different polarities are staggered along the second direction L2; the collector grid lines of the same polarity are aligned along the second direction L2, and the electrode structure further includes: a connecting grid line 23, located between the first battery edge 11 and the end of the collector grid line 21, on the same side in the second direction L2, the connecting grid line 23 electrically connects multiple collector grid lines 21 of the same polarity. Figure 3 On the left side, the connecting gate line 23 electrically connects multiple collector gate lines 21 of the same polarity, that is, on the left side, the connecting gate line 23 electrically connects multiple first polarity collector gate lines 211 of the same polarity; on the right side, the connecting gate line 23 electrically connects multiple collector gate lines 21 of another same polarity, that is, on the right side, the connecting gate line 23 electrically connects multiple second polarity collector gate lines 212 of the same polarity; through the supplementary effect of the connecting gate line 23, the reliability of the electrical connection can be improved, even if the collector gate line has the risk of breaking, effective current collection and conduction can still be guaranteed, and the connecting gate line 23 is more conducive to collecting carriers at the edge of the first battery, which can reduce the resistivity.

[0066] Optional, see Figure 2 , the staggered distance of collector grid lines of different polarities along the second direction L2 is D4; on the same side of the second direction L2, the distance between the geometric centers of the edge electrical connections corresponding to the collector grid lines of the two polarities in the second direction L2 is D3; D3=D4, the offset of the geometric centers of the edge electrical connections corresponding to the collector grid lines of the two polarities on the same side of the second direction L2 in the second direction L2 is compensated by the staggered distance D4 of the collector grid lines of different polarities along the second direction L2, so that it is easy to achieve that the current or carrier collection range or collection distance of the edge electrical connections of the two polarities are roughly equal to the current or carrier collection range or collection distance of the remaining electrical connections, thereby avoiding the performance loss caused by long-distance carrier or current transmission at the location of the edge electrical connection.

[0067] Optional, see Figure 2 , on the same side in the second direction L2, the distance between the geometric centers of the edge electrical connection parts corresponding to the collector grid lines 21 of the two polarities in the second direction L2 is D3; the definition of D3 refers to the above description. The size of the battery body 1 in the second direction L2 is X, and the definition of X here refers to the above description. In the second direction L2, the number of electrical connection parts 22 electrically connected to the collector grid lines 21 of the same polarity is Y, and the number Y is a natural number, and the definition of Y here refers to the above description. D3≤(X / Y-1300μm), when the unit of X / Y is not micrometer, it is converted into micrometer for calculation. Figure 2For the red collector grid line (a collector grid line of one polarity), in the second direction L2, the edge electrical connection portion on the left side electrically connected to it needs to be arranged between the edge electrical connection portion on the left side electrically connected to the black collector grid line and its adjacent electrical connection portion, so that the edge electrical connection portion on the right side electrically connected to the red collector grid line will not be arranged too far to the right, thereby reserving sufficient setting space for the edge electrical connection portion on the right side electrically connected to the red collector grid line. Considering the printing error and accommodating the edge electrical connection portion, (X / Y-1300μm) refers to Figure 2 In the case where the red collector grid line (a collector grid line of one polarity) has its left edge electrical connection portion electrically connected to it in the second direction L2 and is disposed between the left edge electrical connection portion electrically connected to the black collector grid line and its adjacent electrical connection portion, the maximum value of D3 is within the above range, which allows Figure 2 The red collector grid line (a collector grid line of one polarity) has its left edge electrical connection portion electrically connected to it arranged between the left edge electrical connection portion electrically connected to the black collector grid line and its adjacent electrical connection portion in the second direction L2, thereby Figure 2 In the figure, the protruding side of the inward-retracted collector grid line (the red collector grid line) Figure 2 The right side in the figure) should be as close as possible to the edge of the first battery, thereby reserving sufficient setting space for the edge electrical connection part on the right side electrically connected to the red collector grid line, so as to set the edge electrical connection part with a size that meets the requirements.

[0068] For example, for the collector grid lines 21 of both polarities, D2>1.5×D1 and D2<3×D1 are satisfied, and D3 can be X / Y-1300μm, X / Y-1350μm, X / Y-1400μm, X / Y-1450μm, X / Y-1500μm, X / Y-1550μm, X / Y-1600μm, X / Y-1650μm, X / Y-1700μm, X / Y-1800μm, X / Y-1900μm, X / Y-2000μm, X / Y-2100μm, X / Y-2200μm, X / Y-2300μm, X / Y-2500μm, X / Y-3000μm, X / Y-4000μm, or X / Y-5000μm.

[0069] Optional, for Figure 2 The collector grid lines of the two polarities shown in the figure satisfy the conditions of D2>1.5×D1, D2<3×D1, and also satisfy D3≤D2. D3 is not too large. On the one hand, the retracted collector grid line (such as Figure 1 The red collector grid line in the middle) is not too far away from the edge of the first battery, so as to minimize the collection loss of carriers at the edge; secondly, the collector grid line (such as Figure 1The edge electrical connection portion of one side (such as the right side) of the electrical connection of the red collector grid line is not too far outward, reducing the risk of hidden cracks.

[0070] For example, D3 can be D2, 0.2D2, 0.18D2, 0.1D2, 0.08D2, 0.09D2, 0.17D2, 0.16D2, 0.15D2, 0.19D2, 0.14D2, 0.13D2, 0.12D2, and 0.11D2.

[0071] Optionally, 1300μm≤D3≤1400μm. Specifically, since D3 is between the two edge electrical connections, taking into account the printing error and accommodating the edge electrical connection, the minimum value of D3 can be 1300μm; in addition, the value of D3 also needs to consider the welding accuracy of the welding strips that are usually welded to the electrical connection parts in the process of forming the photovoltaic module. At this time, D3 needs to be greater than 1200μm. However, D3 cannot be infinitely large, otherwise it will lead to the ineffective collection of carriers near the edge of the first battery on one side, and the collector grid line is set too close to the edge of the first battery on the other side, which will introduce the risk of hidden cracks. Therefore, 1300μm≤D3≤1400μm can not only be compatible with processing errors and minimize the collection loss of carriers at the edge, but also avoid short circuits and reduce the risk of hidden cracks. It should be noted that the electrical connection part of the present application can be an electrode disk, etc., which is mainly used for electrical connection with interconnecting parts such as welding strips.

[0072] For example, D3 can be 1300 μm, 1320 μm, 1350 μm, 1330 μm, 1360 μm, 1370 μm, 1380 μm, 1380 μm, 1310 μm, 1400 μm.

[0073] Optionally, the battery body 1 also includes: a plurality of doping layers (not shown in the figure) extending along the second direction L2; doping layers of different polarities are spaced and alternately distributed along the first direction L1, one of the doping layers of different polarities is an N-type doping layer and the other is a P-type doping layer, the spacing here can avoid short circuit, and the alternation here means that in the first direction L1, an N-type doping layer is followed by a P-type doping layer and then by an N-type doping layer. The collector grid line is in electrical contact with the doping layers of the same polarity, and the shape of the doping layer is adapted to the shape of the collector grid line of the same polarity, which means that the N-type collector grid line is in electrical contact with the N-type doping layer, and the shape of the N-type doping layer is adapted to the shape of the N-type collector grid line; the P-type collector grid line is in electrical contact with the P-type doping layer, and the shape of the P-type doping layer is adapted to the shape of the P-type collector grid line, so that the doping layers of different polarities are evenly distributed along the second direction L2, and the doping layers of the same polarity are evenly distributed along the second direction L2 to form Figure 1Alternatively, doping layers with different polarities are staggered along the second direction L2, and doping layers with the same polarity are evenly distributed along the second direction L2 to form Figure 2 and Figure 3 A back-contact solar cell is shown.

[0074] The P-type doping layer may contain one or more of the IIIA group elements (for example, boron). The N-type doping layer may contain one or more of the VA group elements (for example, phosphorus). The materials of the N-type doping layer and the P-type doping layer may include any semiconductor material such as silicon, silicon germanium, germanium or gallium arsenide. In terms of the arrangement of the material, the crystal phase of the doping layer may be amorphous, microcrystalline, nanocrystalline, single crystal or polycrystalline. Among them, the materials of the N-type doping layer and the P-type doping layer may be the same or different. For example: the materials of the N-type doping layer and the P-type doping layer may both be doped polycrystalline silicon. For another example: the material of the P-type doping layer may be doped polycrystalline silicon, and the material of the N-type doping layer may include at least one of doped amorphous silicon, doped microcrystalline silicon and doped nanocrystalline silicon. For another example: the material of the P-type doping layer may be doped single crystal silicon, that is, diffused and formed on the surface of the P region of the silicon substrate, and the material of the N-type doping layer may be doped polycrystalline silicon. The P-type doping layer may be prepared by in-situ doping or ex-situ doping. The N-type doping layer may also be prepared by in-situ doping or ex-situ doping.

[0075] Optionally, when the electrical connection portion is a pad, the electrode structure further includes: a plurality of busbars (not shown in the figure) extending along the first direction L1; busbars of different polarities are alternately and spaced along the second direction L2; the collector grid is electrically connected to the busbars of the same polarity and electrically isolated from the busbars of the opposite polarity; the busbars of different polarities refer to N-type busbars and P-type busbars, and the busbars of different polarities are alternately and spaced along the second direction L2, and the spacing here can avoid short circuits, and the alternation here means that in the second direction L2, the N-type busbars are followed by the P-type busbars and then by the N-type busbars. The N-type collector grid is electrically connected to the N-type busbar, and an insulating space is provided between the N-type collector grid and the P-type busbar for electrical isolation, and the P-type collector grid is electrically connected to the P-type busbar, and an insulating space is provided between the P-type collector grid and the N-type busbar for electrical isolation. In the first direction L1, the bus grid lines are intermittently arranged. The electrical connection portion 22 includes: a plurality of first electrical connection portions, electrically connected to the collector grid line, the first electrical connection portion may be a thickened section of the collector grid line itself, or a separately arranged electrical connection portion, in the case where the first electrical connection portion is a thickened section of the collector grid line itself, the line width of the remaining portion of the collector grid line is smaller than the line width of the first electrical connection portion. The first electrical connection portion here may be mainly electrically connected to the collector grid line where the bus grid line is not arranged. The electrical connection portion 22 also includes: a plurality of second electrical connection portions, electrically connected to the bus grid line. In the back-contact solar cell of the present application, there is no need to arrange a bus grid line or the length of the arranged bus grid line is shorter, and current can be collected mainly through the collector grid line, which reduces costs and simplifies the process.

[0076] Here, the second electrical connection portion can be directly arranged on the busbar line to realize electrical connection, or in the second direction L2, there can be a certain distance between the second electrical connection portion and the busbar line, and the electrical connection between the two can be realized by setting a connecting section between the two. The present invention does not make any specific restrictions on this. For example, when the busbar line is close to the edge of the first battery, the second electrical connection portion can be appropriately moved inward. The second electrical connection portion can be a thickened section of the busbar line itself, or a separately arranged electrical connection portion. In the case where the second electrical connection portion is a thickened section of the busbar line itself, the line width of the remaining part of the busbar line is smaller than the line width of the second electrical connection portion.

[0077] Optionally, when the electrical connection portion is a solder pad, the electrode structure further includes: a plurality of bus bars (not shown in the figure) extending along the first direction L1. Bus bars of different polarities are alternately and spaced apart along the second direction L2, and the collector bars are electrically connected to the bus bars of the same polarity and electrically isolated from the bus bars of the opposite polarity. Reference may be made to the aforementioned records to avoid repetition, which will not be described here. In the first direction L1, the bus bars are continuously arranged. The electrical connection portion includes: a plurality of second electrical connection portions, electrically connected to the bus bars, and the electrode structure of the back-contact solar cell is flexible and diverse.

[0078] The configuration of the second electrical connection portion here can refer to the aforementioned related records, and will not be repeated here to avoid repetition.

[0079] It should be noted that, in the case where the busbar lines are intermittently arranged in the first direction L1, in the process of determining Y, a group of busbar lines that are at least partially collinear and intermittently arranged in the first direction L1 is counted as one busbar line. The battery body may also include: a second battery edge, the second battery edge at least having a portion parallel to the second direction L2. For example, Figures 1 to 3 In the embodiment, the second battery edge is the upper battery edge and the lower battery edge, and the first battery edge is the left battery edge and the right battery edge. In the electrode structure, in the first direction L1, when the busbar line is intermittently arranged, the busbar line here can be arranged close to the second battery edge or in the middle, and there is no specific limitation on this. The size of the second electrical connection part in the first direction L1 can be greater than or equal to the size of the first electrical connection part in the first direction L1, and the size of the second electrical connection part in the second direction L2 can be equal to the size of the first electrical connection part in the second direction L2. The sizes of the two in the second direction L2 may also be unequal, and there is no specific limitation on this. There is no specific limitation on the materials of the collector grid lines and electrical connection parts.

[0080] It should be noted that the materials of the above-mentioned collector grid lines, electrical connection parts and bus grid lines include one or more of copper, silver, aluminum, nickel, chromium, silver-aluminum, silver-nickel, silver-chromium, conductive carbon and alloys thereof.

[0081] The present application also provides a photovoltaic module, which may include: a plurality of any of the aforementioned back-contact solar cells, wherein the photovoltaic module includes a plurality of cell strings, wherein the back-contact solar cells in the cell strings are connected in series. The photovoltaic module may also include a packaging film located on both sides of the back-contact solar cell, and other structures of the photovoltaic module are not limited.

[0082] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0083] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A back contact solar cell, characterized in that: include: A battery body and an electrode structure located on one side of the battery body; The battery body includes a first battery edge, wherein the first battery edge has at least a portion parallel to a first direction; the electrode structure includes: A plurality of collector grid lines extending along a second direction; the collector grid lines with different polarities are spaced and alternately distributed along the first direction; the first direction is different from the second direction; A plurality of electrical connection parts electrically connected to the collector grid lines; the electrical connection parts electrically connected to the collector grid lines of the same polarity include: an edge electrical connection part close to the edge of the first battery; On the same side in the second direction, the distance between the end of the collector grid line and the geometric center of the edge electrical connection portion electrically connected thereto is D1; ​​in the second direction, the distance between the geometric centers of adjacent electrical connection portions electrically connected to the collector grid line of the same polarity is D2; For the collector grid line of at least one polarity, D2>1.5×D1, D2<3×D1.

2. The back contact solar cell according to claim 1, characterized in that: On the same side in the second direction, the distance between the geometric centers of the edge electrical connection parts respectively corresponding to the collector grid lines of two polarities in the second direction is D3; The dimension of the battery body in the second direction is X; In the second direction, the number of the electrical connection parts electrically connected to the collector grid lines of the same polarity is Y; D3≤X / (4Y).

3. The back contact solar cell according to claim 1, characterized in that: On the same side in the second direction, the distance between the geometric centers of the edge electrical connection parts respectively corresponding to the collector grid lines of two polarities in the second direction is D3; For the collector grid line of at least one polarity, D2>1.5×D1, D2<3×D1, and D3 is less than or equal to (1 / 2) of D1.

4. The back contact solar cell according to claim 1, characterized in that: The collector grid lines with the same polarity are distributed in parallel along the second direction, and the collector grid lines with different polarities are distributed staggered along the second direction, and the staggered distance between the ends of the collector grid lines along the second direction is D4; On the same side in the second direction, the distance between the geometric centers of the edge electrical connection parts respectively corresponding to the collector grid lines of two polarities in the second direction is D3; Where D3 = D4; For the collector grid lines of two polarities, D2>1.5×D1 and D2<3×D1 are satisfied.

5. The back contact solar cell according to claim 4, characterized in that: On the same side in the second direction, the distance between the geometric centers of the edge electrical connection parts respectively corresponding to the collector grid lines of two polarities in the second direction is D3; The dimension of the battery body in the second direction is X; In the second direction, the number of the electrical connection parts electrically connected to the collector grid lines of the same polarity is Y; D3≤(X / Y-1300μm).

6. The back contact solar cell according to any one of claims 2 to 5, characterized in that: 1300μm≤D3≤1400μm.

7. The back contact solar cell according to claim 4, characterized in that: The electrode structure further comprises: The connecting grid line is located between the edge of the first battery and the collector grid line. On the same side in the second direction, the connecting grid line electrically connects a plurality of the collector grid lines of the same polarity.

8. The back-contact solar cell according to any one of claims 1 to 5 and 7, characterized in that: The electrode structure further comprises: a plurality of busbar lines extending along the first direction; busbar lines of different polarities are alternately and spaced apart along the second direction; the collector lines are electrically connected to busbar lines of the same polarity and electrically isolated from busbar lines of the opposite polarity; in the first direction, the busbar lines are intermittently arranged; The electrical connection portion includes: a plurality of first electrical connection portions electrically connected to the collector grid lines, and a plurality of second electrical connection portions electrically connected to the bus grid lines.

9. The back-contact solar cell according to any one of claims 1 to 5 and 7, characterized in that: The electrode structure further comprises: a plurality of busbar lines extending along the first direction; busbar lines of different polarities are alternately and spaced apart along the second direction; the collector lines are electrically connected to the busbar lines of the same polarity and electrically isolated from the collector lines of the opposite polarity; in the first direction, the busbar lines are continuously arranged; The electrical connection portion includes: a plurality of second electrical connection portions electrically connected to the busbar lines.

10. The back-contact solar cell according to any one of claims 1 to 5 and 7, characterized in that: For the collector grid line of at least one polarity, D1 = (1 / 2) × D2.

11. A photovoltaic module, characterized in that: include: A plurality of cell strings, each cell string comprising a plurality of back-contact solar cells as claimed in any one of claims 1 to 10.

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