Surface electrode structure and solar cell

Abstract

The utility model relates to a surface electrode structure and a solar cell. The surface electrode structure comprises a main grid structure and an auxiliary grid structure. The main grid structure comprises a plurality of mutually parallel main grid lines, each main grid line is provided with a plurality of bonding pads, and the auxiliary grid structure comprises a first auxiliary grid line and a second auxiliary grid line which are mutually parallel. The first auxiliary grid lines intersect with the main grid lines so as to be electrically connected with the main grid lines, and the second auxiliary grid lines are connected with the bonding pads through the second inclined sections and are also electrically connected with the main grid lines. As the width of the welding strip is generally smaller than that of the bonding pad, the welding strip can be arranged in the middle relative to the bonding pad and penetrates through the gap between the two second linear sections. Therefore, the second auxiliary grid lines do not extend to the lower part of the welding strip, and the second auxiliary grid lines can be prevented from playing a role in raising the welding strip. Therefore, when the welding strip and the welding pad are welded, the welding strip and the welding pad can be attached more tightly, pseudo soldering between the welding pad and the welding strip is effectively avoided, and therefore the welding effect of the welding strip and the welding pad is improved.

Description

Technical Field

[0001] This utility model relates to the field of solar cell technology, and in particular to a surface electrode structure and a solar cell. Background Technology

[0002] In the production of solar cells, printing metal paste onto the silicon wafer surface to form metal electrodes for collecting current is a crucial step. These metal electrodes typically consist of a main grid and a sub-grid. The main grid mainly comprises pads and main grid lines, while the sub-grid mainly comprises sub-grid lines, which are perpendicularly connected to the main grid lines and pads. The sub-grid lines are generally taller than the pads. During module soldering, sub-grid lines that are too close to the pads can negatively impact the solder ribbon, leading to cold solder joints. Utility Model Content

[0003] Therefore, it is necessary to provide a surface electrode structure and solar cell that can improve the welding effect with solder strips to address the above problems.

[0004] A surface electrode structure, comprising:

[0005] The main gate structure includes multiple parallel main gate lines extending along a first direction, and each main gate line is provided with multiple pads; and

[0006] The sub-gate structure includes a first sub-gate line and a second sub-gate line that are parallel to each other and extend along a second direction, the second direction being perpendicular to the first direction. The first sub-gate line intersects the main gate line. The second sub-gate line includes a plurality of spaced second straight segments. The second straight segments are spaced from the pads along the first direction, and the end of each second straight segment extends into a second inclined segment that is inclined relative to the second straight segment, the second inclined segment extending to the pad.

[0007] In one embodiment, each of the regions where the first sub-gate line intersects with the main gate line forms a first widening segment, the linewidth of the first widening segment being greater than the linewidth of the remaining regions of the main gate line.

[0008] In one embodiment, a second widening segment is formed between each of the second straight segments and the second inclined segment, the line width of the second widening segment being greater than the line width of the remaining area of ​​the second straight segment.

[0009] In one embodiment, the orthographic projection of the second inclined segment onto the pad surface in both the first and second directions has a size between 0.05 mm and 0.20 mm.

[0010] In one embodiment, in the first direction, the shortest distance between the second straight line segment and the edge of the pad along the first direction is less than 0.05 mm.

[0011] In one embodiment, the subgate mechanism further includes a third subgate line extending along the second direction, the third subgate line including a plurality of spaced third straight segments extending to the edge of the pad along the second direction, and the end of each third straight segment extending into a third inclined segment inclined relative to the third straight segment, the third inclined segment extending to the pad.

[0012] In one embodiment, a third widening segment is formed between each of the third straight segments and the third inclined segment, the line width of the third widening segment being greater than the line width of the remaining area of ​​the third straight segment.

[0013] In one embodiment, the orthographic projection of the third inclined segment onto the pad surface in both the first and second directions has a size between 0.05 mm and 0.20 mm.

[0014] In one embodiment, in the first direction, the shortest distance between the third straight line segment and the edge of the pad along the first direction is less than 0.05 mm.

[0015] A solar cell includes a silicon wafer and a surface electrode structure as described in any of the preferred embodiments above, the surface electrode structure being formed on at least one side of the silicon wafer, both the front and back sides.

[0016] In the aforementioned surface electrode structure and solar cell, the first sub-grid line intersects with the main grid line, thus achieving electrical connection with the main grid line. The second sub-grid line connects to the pad via a second inclined segment, also achieving electrical connection with the main grid line. Since the width of the solder ribbon is typically smaller than the width of the pad, the solder ribbon can be centered relative to the pad and pass through the gap between the two second straight segments. This prevents the second sub-grid line from extending below the solder ribbon, avoiding its role in raising the solder ribbon. During soldering, the solder ribbon and pad can adhere more tightly, effectively preventing cold solder joints between the pad and the solder ribbon, thereby improving the soldering effect. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the solar cell in a preferred embodiment of the present invention;

[0019] Figure 2 for Figure 1 The diagram shows the structure of the surface electrode in the solar cell.

[0020] Figure 3 for Figure 2 A magnified schematic diagram of part A in the surface electrode structure shown;

[0021] Figure 4 for Figure 2 A magnified schematic diagram of part B in the surface electrode structure shown. Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0023] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0025] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0026] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0027] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0028] Please see Figure 1 This utility model provides a solar cell 10 and a surface electrode structure 100. The solar cell 10 includes a silicon wafer 200 and a surface electrode structure 100.

[0029] The surface electrode structure 100 can be formed on the front, back, or both sides of the silicon wafer 200. The surface electrode structure 100 serves to collect and transport electrons and can be made of silver, aluminum, or other conductive materials. It is typically formed on the surface of the silicon wafer 200 by methods such as screen printing or deposition. When the solar cell 10 is exposed to light, the silicon wafer 200 converts light energy into electrical energy, generating electrons and holes. The surface electrode structure 100 can guide current to the edge of the silicon wafer 200, thereby facilitating the collection and utilization of the converted electrical energy by external circuitry.

[0030] The surface electrode structure 100 can also be welded to the solder strip (not shown) to collect current and connect multiple solar cells 10 into one unit. Thus, the electrical energy generated by the multiple solar cells 10 individually is discharged and collected, and finally a solar cell capable of outputting higher voltage and current can be obtained.

[0031] Please refer to the following: Figure 2 In a preferred embodiment of the present invention, the surface electrode structure 100 includes a main gate structure 110 and a secondary gate structure 120.

[0032] Both the main gate structure 110 and the sub-gate structure 120 can be formed by screen printing. Generally, the main gate structure 110 is screen printed first on the surface of the silicon wafer 200, and then the sub-gate structure 120 is screen printed, making the surface electrode structure 100 as a whole a mesh. When screen printing the main gate structure 110, a highly fluid paste is usually used, so the height of the printed pattern is relatively low, generally only about 5µm; while the paste used for screen printing the sub-gate structure 120 usually needs to ensure a certain line shape, so the height of the printed pattern is higher, generally greater than 8µm.

[0033] The main gate structure 110 includes multiple main gate lines 111, which are parallel to each other and extend along a first direction. Specifically, the first direction refers to the vertical direction shown in the figure, i.e. Figure 2 The vertically extending lines shown are the main grid lines 111. The main grid lines 111 are relatively wide metal lines responsible for collecting current and transmitting it to the output terminal of the solar cell 10. Furthermore, each main grid line 111 is provided with multiple pads 112, which are spaced apart along the extension direction of the main grid line 111. The pads 112 are used for soldering with solder ribbons (not shown), which extend along a first direction, and generally one solder ribbon is provided for each main grid line 111. The solder ribbons are positioned along the corresponding main grid line 111, and their width is generally smaller than the width of the pads 112.

[0034] The sub-gate structure 120 includes multiple sub-gate lines, which are thinner than the main gate lines 111 and extend from the main gate lines 111 to the region where electron-hole pairs are generated, thereby helping to collect electrons dispersed on the surface of the silicon wafer 200. The multiple sub-gate lines are parallel to each other and extend along a second direction, which is perpendicular to the first direction. Specifically, the second direction refers to the horizontal direction shown in the figure, i.e. Figure 2 The lines extending horizontally shown are the sub-grid lines.

[0035] Based on the different relative positions of the sub-gate lines and the main gate lines 111, the sub-gate lines are divided into a first sub-gate line 121, a second sub-gate line 122, and a third sub-gate line 123. The first sub-gate line 121 is farther from the pad 112 in the first direction, generally greater than 0.05 mm; the second sub-gate line 122 is closer to the pad 112 in the first direction, generally less than 0.05 mm; and the third sub-gate line 123 passes through the pad 112 along the second direction. Of course, the types of sub-gate lines are not limited to the above three, but this application does not cover them, so they will not be elaborated here.

[0036] Please refer to the following: Figure 3 The first sub-gate line 121 intersects with the main gate line 111, thereby achieving electrical connection with the main gate line 111. Each first sub-gate line 121 intersects with multiple main gate lines 111, thus forming multiple intersection points on each first sub-gate line 121. Specifically, in this embodiment, a first widening section 1211 is formed in the area where each first sub-gate line 121 intersects with the main gate line 111. The linewidth of the first widening section 1211 is greater than the linewidth of the remaining areas of the main gate line 111. By increasing the linewidth, the metal content and structural strength of the first sub-gate line 121 in the intersection area can be increased. In this way, the melting of the first sub-gate line 121 in the intersection area can be avoided when welding with solder strips.

[0037] Furthermore, the second sub-gate line 122 includes multiple spaced second straight segments 1221, which are spaced from the pad 112 along the first direction. That is, each second sub-gate line 122 is not a single continuous metal line, but rather has multiple gaps in the middle, dividing it into multiple second straight segments 1221. The second sub-gate line 122 does not intersect with the main gate line 111, which passes through the gaps in the second sub-gate line 122. The distance between the second sub-gate line 122 and the pad 112 refers to the distance between the second straight segment 1221 and the pad 112. Therefore, in the first direction, the shortest distance between the second straight segment 1221 and the edge of the pad 112 along the first direction is less than 0.05 mm.

[0038] Each second straight segment 1221 extends from its end into a second inclined segment 1222, which is inclined relative to the second straight segment 1221 and extends to the pad 112. The second inclined segment 1222 is connected to the pad 112, thereby electrically connecting the second straight segment 1221 to the pad 112. In this way, the second sub-gate line 122 is also electrically connected to the main gate line 111.

[0039] Since the width of the solder strip is smaller than the width of the pad 112, when soldering the solder strip to the pad 112, the solder strip can be centered relative to the pad 112 and pass through the gap between the two second straight segments 1221. In this way, a portion of the two side edges of the pad 112 in the width direction (second direction) will not be covered by the solder strip, and the second sub-gate line 122 can extend to this area without extending below the solder strip. This avoids the second sub-gate line 122 from acting as a padding element for the solder strip, effectively preventing the formation of cold solder joints between the pad 112 and the solder strip.

[0040] Specifically, in this embodiment, a second widening segment 1223 is formed between each second straight segment 1221 and the second inclined segment 1222. The linewidth of the second widening segment 1223 is greater than the linewidth of the remaining area of ​​the second straight segment 1221. The function of the second widening segment 1223 is the same as that of the first widening segment 1211, which can also improve the structural strength of the second sub-grid line 122 and prevent the second sub-grid line 122 from melting during solder strip welding.

[0041] More specifically, in this embodiment, the orthographic projection of the second inclined segment 1222 onto the surface of the pad 112 has dimensions between 0.05 mm and 0.20 mm in both the first and second directions. That is, the length of the second inclined segment 1222 extending into the pad 112 in both the first and second directions is between 0.05 mm and 0.20 mm. If this length is less than 0.05 mm, the connection between the second inclined segment 1222 and the pad 112 will be less reliable; while if the length is greater than 0.20 mm, the second inclined segment 1222 will occupy a large space on the surface of the pad 112, thus causing interference with the solder ribbon.

[0042] In addition, please refer to the following: Figure 4 In this embodiment, the third sub-gate line 123 includes a plurality of spaced third straight segments 1231, the third straight segments 1231 extending to the edge of the pad 112 along the second direction, and the end of each third straight segment 1231 extends into a third inclined segment 1232 that is inclined relative to the third straight segment 1231, the third inclined segment 1232 extending to the pad 112.

[0043] The third sub-gate line 123 has the same structure as the second sub-gate line 122, except that its relative position to the pad 112 is different. Specifically, each third sub-gate line 123 is not a complete metal line, but has multiple gaps in the middle, which divide the third sub-gate line 123 into multiple third straight segments 1231. The third sub-gate line 123 does not intersect with the main gate line 111, and the pad 112 passes through the gaps on the third sub-gate line 123.

[0044] The third sub-gate line 123 is relatively close to the edge of the pad 112. Specifically, in this embodiment, in the first direction, the shortest distance between the third straight line segment 1231 and the edge of the pad 112 along the first direction is less than 0.05 mm. During the screen printing process, the stencil may deform or shift along the first direction. When the deformation or shift exceeds the distance between the third sub-gate line 123 and the edge of the pad 112, the third sub-gate line 123 will detach from the pad 112 along the first direction, thereby causing the surface electrode structure 100 to fail.

[0045] By setting the third inclined segment 1232, the effective contact distance between the third sub-gate line 123 and the pad 112 in the first direction can be increased. Therefore, even if the screen is deformed or shifted along the first direction during the screen printing process, because there is sufficient margin between the third inclined segment 1232 and the pad 112, it is not easy for the third sub-gate line 123 to detach from the pad 112 and cause the surface electrode structure 100 to fail.

[0046] Furthermore, in this embodiment, a third widening segment 1233 is formed between each third straight segment 1231 and the third inclined segment 1232. The line width of the third widening segment 1233 is greater than the line width of the remaining area of ​​the third straight segment 1231. The function of the third widening segment 1233 is the same as that of the first widening segment 1211 and the second widening segment 1223, which can also improve the structural strength of the third sub-gate line 123 and prevent the third sub-gate line 123 from melting during soldering.

[0047] Specifically, in this embodiment, the orthographic projection of the third inclined segment 1232 onto the surface of the pad 112 has dimensions between 0.05 mm and 0.20 mm in both the first and second directions. Similarly, the length of the third inclined segment 1232 extending into the pad 112 in both the first and second directions is between 0.05 mm and 0.20 mm. If this length is less than 0.05 mm, the reliability of the connection between the third inclined segment 1232 and the pad 112 will be poor; while if this length is greater than 0.20 mm, the third inclined segment 1232 will occupy a large space on the surface of the pad 112, thereby causing interference with the solder ribbon.

[0048] In the aforementioned surface electrode structure 100 and solar cell 10, the first sub-grid line 121 intersects with the main grid line 111, thus achieving electrical connection with the main grid line 111. The second sub-grid line 122 is connected to the pad 112 via a second inclined segment 1222, also achieving electrical connection with the main grid line 111. Since the width of the solder strip is usually smaller than the width of the pad 112, the solder strip can be centered relative to the pad 112 and pass through the gap between the two second straight segments 1221. In this way, the second sub-grid line 122 will not extend below the solder strip, avoiding the second sub-grid line 122 from elevating the solder strip. When the solder strip is soldered to the pad 112, the solder strip and the pad 112 can fit more tightly, effectively avoiding the formation of cold solder joints between the pad 112 and the solder strip, thereby improving the soldering effect.

[0049] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A surface electrode structure, characterized in that, include: The main gate structure includes multiple parallel main gate lines extending along a first direction, and each of the main gate lines is provided with multiple pads; and The sub-gate structure includes a first sub-gate line and a second sub-gate line that are parallel to each other and extend along a second direction, the second direction being perpendicular to the first direction. The first sub-gate line intersects the main gate line. The second sub-gate line includes a plurality of spaced second straight segments. The second straight segments are spaced from the pads along the first direction, and the end of each second straight segment extends into a second inclined segment that is inclined relative to the second straight segment, the second inclined segment extending to the pad.

2. The surface electrode structure according to claim 1, characterized in that, Each region where the first sub-gate line intersects with the main gate line forms a first widening segment, the linewidth of which is greater than the linewidth of the remaining region of the main gate line.

3. The surface electrode structure according to claim 1, characterized in that, A second widening segment is formed between each of the second straight segments and the second inclined segment, and the line width of the second widening segment is greater than the line width of the remaining area of ​​the second straight segment.

4. The surface electrode structure according to claim 1, characterized in that, The dimensions of the orthographic projection of the second inclined segment onto the surface of the pad in both the first and second directions are between 0.05 mm and 0.20 mm.

5. The surface electrode structure according to claim 1, characterized in that, In the first direction, the shortest distance between the second straight line segment and the edge of the pad along the first direction is less than 0.05 mm.

6. The surface electrode structure according to claim 1, characterized in that, The sub-gate structure further includes a third sub-gate line extending along the second direction. The third sub-gate line includes a plurality of spaced third straight segments. The third straight segments extend to the edge of the pad along the second direction, and the end of each third straight segment extends a third inclined segment that is inclined relative to the third straight segment and extends to the pad.

7. The surface electrode structure according to claim 6, characterized in that, A third widening segment is formed between each of the third straight segments and the third inclined segment, and the line width of the third widening segment is greater than the line width of the remaining area of ​​the third straight segment.

8. The surface electrode structure according to claim 6, characterized in that, The dimensions of the orthographic projection of the third inclined segment onto the pad surface in both the first and second directions are between 0.05 mm and 0.20 mm.

9. The surface electrode structure according to claim 6, characterized in that, In the first direction, the shortest distance between the third straight line segment and the edge of the pad along the first direction is less than 0.05 mm.

10. A solar cell, characterized in that, The invention includes a silicon wafer and a surface electrode structure as described in any one of claims 1 to 9, wherein the surface electrode structure is formed on at least one side of the front and back of the silicon wafer.

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