Electrode structure of back contact cell, back contact cell, back contact cell module, and back contact cell system

Abstract

SOLUTION: The present invention belongs to a technical field of solar cells, and more particularly to an electrode structure of a back contact cell, a back contact cell, a back contact cell module, and a back contact cell system. Therein the electrode structure includes first grid lines for collecting a first polarity region; second grid lines for collecting a second polarity region; a first main grid disposed on a side of the back contact cell close to a first edge and connected to the first grid line; first pad points; and first connection electrodes respectively connected to the first main grid and the first pad points. A distance between each of the first pad points and the first edge is greater than a distance between the first main grid and the first edge.EFFECT: An electrode structure can improve reliability, reduce costs, increase the product yield, and ensure very excellent photoelectric conversion efficiency.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to the technical field of solar cells, and particularly to an electrode structure of a back-contact cell, a back-contact cell, a back-contact cell module and a back-contact cell system. [Background technology]

[0002] Solar cells are semiconductor devices that convert light energy into electrical energy, and lower manufacturing costs and higher energy conversion efficiency are always sought after goals in the solar cell industry. Current solar cells typically have emitter and base contact electrodes on the front and back of the cell sheet, respectively. The front of the cell is the light-receiving surface, and the coverage of the front metal emitter contact electrode inevitably causes a portion of the incident sunlight to be reflected and blocked by the metal electrode, resulting in some light loss. The coverage area of the front metal electrode of a typical crystalline silicon solar cell is about 7%. Reducing the front metal electrode coverage can directly improve the energy conversion efficiency of the cell.

[0003] In response to the above, the industry has proposed back-contact solar cells, which are cells in which both the emitter and base contact electrodes are located on the back (non-light-receiving) surface of the cell, and the light-receiving surface of the cell is not shielded by any metal electrodes, which effectively increases the short-circuit current of the cell sheet, and also allows for wider metal grid lines on the back surface to reduce the series resistance and improve the fill factor. Such cells, which have no shielding on the front surface, not only have higher conversion efficiency, but also have a more aesthetically pleasing appearance, and are easier to assemble into modules with all back electrodes.

[0004] The core technology of back contact solar cells is electrode pattern design. There are three types of electrode pattern designs for conventional back contact solar cells:

[0005] 1. Referring to Figure 1, insulating adhesive 3 is printed on opposite electrodes to form insulation, while exposing the same-sex electrodes. Then, pad 1 and busbar 2 are printed to connect the same-sex electrodes. However, insulating adhesive 3 cannot withstand high temperatures. Pad 1 and busbar 2 are formed by post-printing. Therefore, only low-temperature paste can be used for pad 1 and busbar 2, which increases costs and poses reliability issues. To achieve good insulation, insulating adhesive 3 must be approximately 30 μm high. To avoid disconnections, pad 1 and busbar 2 must exceed 30 μm in height, resulting in high paste consumption and further increasing costs. Furthermore, insulating adhesive 3 and some pastes have issues such as poor adhesion, making mass production a significant challenge.

[0006] 2. Referring to Figure 2, the fine grid 4 is cut at the isotropic pad points 5 and busbars 6, and the edge pad points 5 and busbars 6 are located at the belly edge of the silicon wafer. The pad points 5 and busbars 6 are located at the edge of the silicon wafer. During the module manufacturing process, the ribbon must also cover the edge of the silicon wafer. A large number of microcracks exist at the edge of the silicon wafer, which can cause stress concentration during the ribbon welding process, leading to the silicon wafer breaking, reducing the yield and reliability of the module.

[0007] 3. Referring to FIG. 3, the fine grid 7 is cut by the isomeric pads 8 and bus bars 9, the outer pads 8 and bus bars 9 are spaced a certain distance from the belly edge of the silicon wafer, and the periphery of the outer pads 8 and bus bars 9 is set to the same polarity. The third design solves the problems present in the first and second designs described above, but the photo-generated electrons and holes must diffuse into the isomeric region to form an efficient collection. In the third design, the outer photo-generated electrons and holes must travel distances on the order of millimeters or even centimeters to reach the isomeric region. Recombination losses during long-distance diffusion reduce the short-circuit current and increase the series resistance, resulting in a loss of fill factor and significantly lower photoelectric conversion performance.

[0008] Therefore, in order to solve the above problems, designing the electrode structure of the back-contact battery, the back-contact battery, the back-contact battery module and the back-contact battery system has always been one of the important issues that should be studied by those skilled in the art. Summary of the Invention

[0009] The present invention provides an electrode structure for back-contact cells to solve the technical problems of traditional back-contact solar cells, such as high cost, low reliability and low photoelectric conversion performance.

[0010] The present invention is realized as follows.

[0011] a first grid line for collecting a first polarity region; a second grid line for collecting a second polarity region; a first main grid disposed near a first edge of the back contact cell and connected to the first grid line; First pad point, a first connection electrode connecting the first main grid and the first pad point, A distance between the first pad point and the first edge is greater than a distance between the first main grid and the first edge, providing a back-contact battery electrode structure.

[0012] Furthermore, the second grid lines include first curved grid lines located between the first major grid and the first pad point, and the first curved grid lines are curved toward the first major grid and the first pad point, respectively, and neither of them is in contact with the first major grid or the first pad point, or the first curved grid lines are curved toward the first major grid and are not in contact with the first major grid, or the first curved grid lines are curved toward the first pad point and are not in contact with the first pad point.

[0013] Additionally, the first curved grid lines pass through at least one of the first grid lines.

[0014] Furthermore, the center line of the first connection electrode and the center line of the first pad point are not on the same straight line.

[0015] Furthermore, the electrode structure further includes a third grid line connecting the first main grid and the first pad point, respectively, the third grid line being located adjacent to the first connection electrode, and the width of the third grid line being smaller than the width of the first connection electrode.

[0016] Furthermore, the second grid lines are covered with a first insulating material in partial regions located on the center lines of the first pad points.

[0017] Furthermore, the distance between the first main grid and the first edge is 0.01 mm to 3 mm.

[0018] Furthermore, the distance between the first pad point and the first edge is 1 mm to 20 mm.

[0019] Furthermore, the electrode structure is a second main grid disposed near a second edge of the back-contact cell opposite the first edge and connected to the second grid line; The second pad point, and a second connection electrode connecting the second main grid and the second pad point, respectively; The distance between the second pad point and the second edge is greater than the distance between the second major grid and the second edge.

[0020] Furthermore, the first grid lines include second curved grid lines located between the second major grid and the second pad point, and the second curved grid lines are curved toward the second major grid and the second pad point, respectively, and neither of them is in contact with the second major grid or the second pad point, or the second curved grid lines are curved toward the second major grid and are not in contact with the second major grid, or the second curved grid lines are curved toward the second pad point and are not in contact with the second pad point.

[0021] Additionally, the second curved grid lines pass through at least one of the second grid lines.

[0022] Furthermore, the center line of the second connection electrode and the center line of the second pad point are on the same straight line.

[0023] Furthermore, the electrode structure further includes a fourth grid line connecting the second main grid and the second pad point, respectively, the fourth grid line being located adjacent to the second connecting electrode, and the width of the fourth grid line being smaller than the width of the second connecting electrode.

[0024] Furthermore, the first grid lines are covered with a second insulating material in partial regions located on the center lines of the second pad points.

[0025] Furthermore, the distance between the second main grid and the second edge is 0.01 mm to 3 mm.

[0026] Furthermore, the distance between the second pad point and the second edge is 1 mm to 20 mm.

[0027] The present invention further provides a back-contact cell, which includes the electrode structure described above, wherein the electrode structure is disposed on a backlight surface of the back-contact cell.

[0028] The present invention further provides a back-contact battery module comprising the back-contact batteries described above.

[0029] The present invention further provides a back-contact battery system including the back-contact battery module described above.

[0030] The beneficial effects of the present invention are that the electrode structure includes a first grid line, a second grid line, a first main grid, a first pad point, and a first connecting electrode connecting the first main grid and the first pad point, respectively, to achieve current collection. The electrode structure does not require large-area printing of insulating adhesive, and the first pad point is not located at the first edge of the back-contact cell together with the first main grid. Photogenerated electrons and holes do not need to travel long distances to reach the isomeric region. This improves reliability, reduces costs, and increases product yield, while ensuring excellent photoelectric conversion efficiency. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a schematic diagram of a first electrode pattern design according to the prior art. [Figure 2] FIG. 10 is a schematic diagram of a second electrode pattern design according to the prior art. [Figure 3] FIG. 10 is a schematic diagram of a third electrode pattern design according to the prior art. [Figure 4] 1 is a schematic diagram of an electrode structure provided in an embodiment of the present invention. [Figure 5] 1 is a schematic diagram of an electrode structure provided with curved grid lines extending toward pad points and a main grid, respectively, provided in an embodiment of the present invention. FIG. [Figure 6] 1 is a schematic diagram of an electrode structure provided with curved grid lines extending towards the main grid provided in an embodiment of the present invention; FIG. [Figure 7] 1 is a schematic diagram of an electrode structure provided with curved grid lines extending towards pad points provided in an embodiment of the present invention. [Figure 8]1A and 1B are schematic diagrams of electrode structures with different gridline designs on both edge sides of a back-contact battery provided in an embodiment of the present invention. [Figure 9] 1 is a schematic diagram of an electrode structure provided with third and fourth grid lines according to an embodiment of the present invention; FIG. [Figure 10] 1 is a schematic diagram of an electrode structure provided with a first insulating material and a second insulating material according to an embodiment of the present invention; [Figure 11] FIG. 10 is an edge model diagram of a second electrode pattern design according to the prior art. [Figure 12] FIG. 10 is an edge model diagram of a third electrode pattern design according to the prior art. [Figure 13] FIG. 5 is a diagram of an edge model based on the electrode structure of FIG. [Figure 14] FIG. 10 is a diagram of an edge model based on the electrode structures of FIGS. 5 to 9. DETAILED DESCRIPTION OF THE INVENTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in more detail below in conjunction with the drawings and examples. It should be understood that the specific examples described herein are only for the purpose of illustrating the present invention, and are not intended to limit the present invention.

[0033] The present invention provides an electrode structure for a back-contact battery, including first grid lines, second grid lines, a first main grid, a first pad point, and a first connecting electrode connecting the first main grid and the first pad point. The first grid lines are used to collect current from a first polarity region, which is then joined to the first main grid through the first pad point and the first connecting electrode. The electrode structure does not require large-area printing of insulating adhesive, and the first pad point is not located at the first edge of the back-contact battery together with the first main grid. Photogenerated electrons and holes do not need to travel long distances to reach the opposite-polarity region. This electrode structure improves reliability, reduces costs, and increases product yield, while ensuring excellent photoelectric conversion efficiency. Example 1

[0034] Referring to FIG. 4, this Example 1 is a first grid line 10 for collecting a first polarity region; a second grid line 20 for collecting a second polarity region; a first main grid 51 located near the first edge of the back contact cell and connected to the first grid line 10; The first pad point is 31, a first connection electrode (41) connecting the first main grid (51) and the first pad point (31), The distance between the first pad point 31 and the first edge is greater than the distance between the first main grid 51 and the first edge, providing a back-contact battery electrode structure.

[0035] In an embodiment of the present invention, the first grid line 10 is used to collect current in a first polarity region, and the second grid line 20 is used to collect current in a second polarity region. Since the polarities of the first grid line 10 and the second grid line 20 are opposite, the polarities of the first polarity region and the second polarity region are also opposite. For example, if the first grid line 10 is a positive grid line for collecting positive current in a positive polarity region, the second grid line 20 is a negative grid line for collecting negative current in a negative polarity region. Alternatively, if the first grid line 10 is a negative grid line for collecting negative current in a negative polarity region, the second grid line 20 is a positive grid line for collecting positive current in a positive polarity region. Here, the positive grid line is located in a P-type doped region of a back-contacted cell, and the negative grid line is located in an N-type doped region of a back-contacted cell.

[0036] 4 to 10, for ease of distinction, the first grid lines 10 in the blackened areas have the same polarity, and the second grid lines 20 in the unblackened areas have the same polarity, with the polarities of the first grid lines 10 and the second grid lines 20 being opposite to each other. The first pad points 31, the first connection electrodes 41, and the first main grids 51 in the blackened areas have the same polarity as the first grid lines 10.

[0037] The first grid lines 10 and the second grid lines 20 are alternately arranged, and both the first grid lines 10 and the second grid lines 20 are horizontal to the edge lines of the back-contact battery. For example, referring to FIG. 4, the first grid lines 10 and the second grid lines 20 are alternately arranged vertically, and both the first grid lines 10 and the second grid lines 20 are horizontal to the top and bottom edge lines of the back-contact battery. The back-contact battery is substantially rectangular. The substantially rectangular back-contact battery may be, for example, a square or other rectangular shape, and may have standard corners, cut-off corners, or rounded corners, which are determined according to actual manufacturing requirements and are not specifically limited herein. The number of first grid lines 10 and second grid lines 20 is determined according to the area size of the actual back-contact battery and the width and distance of the first grid lines 10 and the second grid lines 20 and are not specifically limited herein.

[0038] Furthermore, the first grid lines 10 or the second grid lines 20 are aluminum grid lines, silver grid lines, copper grid lines, or silver-coated copper grid lines. It is understood that in embodiments of the present invention, the first grid lines 10 and the second grid lines 20 may be selected to be the same or different metal types. For example, the first grid lines 10 and the second grid lines 20 may both be aluminum grid lines, or the first grid line 10 may be aluminum grid lines and the second grid line 20 may be silver grid lines. If the first grid lines 10 or the second grid lines 20 are aluminum grid lines or silver grid lines, the aluminum grid lines or silver grid lines are printed on the doped regions of the back-contact cells by screen printing. If the first grid lines 10 or the second grid lines 20 are copper grid lines, the aluminum grid lines or silver grid lines are plated on the doped regions of the back-contact cells by electroplating, vapor deposition, or the like.

[0039] The distance between the first pad point 31 and the first edge is greater than the distance between the first main grid 51 and the first edge. For example, referring to FIG. 4, the distance between the leftmost side of the first pad point 31 and the leftmost edge of the back-contact battery is greater than the distance between the leftmost side of the first main grid 51 and the leftmost edge of the back-contact battery.

[0040] In this embodiment, the distance between the first major grid 51 and the first edge is 0.01 mm to 3 mm, which refers to the distance between the edge closest to the first edge of the first major grid 51 and the first edge. For example, the distance between the first major grid 51 and the first edge is 0.05 mm, 1 mm, 2 mm, 3 mm, or another parameter value between 0.01 mm and 3 mm. The distance between the first pad point 31 and the first edge is 1 mm to 20 mm, which refers to the distance between the edge closest to the first edge of the first pad point 31 and the first edge. For example, the distance between the first pad point 31 and the first edge is 1 mm, 5 mm, 10 mm, 20 mm, or another parameter value between 1 mm and 20 mm, but the distance between the first pad point 31 and the first edge is greater than the distance between the first major grid 51 and the first edge.

[0041] In this embodiment, the first pad point 31 is located away from the first main grid 51, and the connection between the first pad point 31 and the first main grid 51 is realized by the connection action of the first connecting electrode 41. Since the first main grid 51 is located at the first edge of the back-contacted battery, the first pad point 31 is far away from the first edge of the back-contacted battery. In the current collection process, the first grid line 10 collects the current of the first polarity region, and then the first grid line 10 transmits the collected current to the first pad point 31 and further from the first pad point 31 to the first main grid 51 via the first connecting electrode 41 to complete the current collection. Compared to the first electrode pattern design of the background art, the electrode structure of the present invention eliminates the need for large-area printing of insulating adhesive, allowing the first pad point 31 and first main grid 51 to use high-temperature paste, reducing costs and ensuring reliability. Furthermore, the first pad point 31 and first main grid 51 do not require excessive height, reducing paste consumption. The elimination of large-area printing of insulating adhesive eliminates the problem of poor adhesion with some pastes, easing mass production. Compared to the second electrode pattern design of the background art, the first main grid 51 is located at the first edge of the back-contact cell, and the first pad point 31 is farther away from the first edge of the back-contact cell, avoiding stress concentration during the welding process and improving module yield and reliability. Compared to the third electrode pattern design of the background art, photogenerated electrons and holes can reach the isomer region without traveling long distances to achieve current collection, fully ensuring higher photoelectric conversion efficiency. Example 2

[0042] Based on Example 1, the second grid lines 20 described in Example 2 include first curved grid lines located between the first main grid 51 and the first pad point 31, and the first curved grid lines are curved toward the first main grid 51 and the first pad point 31, respectively, and are not in contact with either the first main grid 51 or the first pad point 31, or the first curved grid lines are curved toward the first main grid 51 and are not in contact with the first main grid 51, or the first curved grid lines are curved toward the first pad point 31 and are not in contact with the first pad point 31.

[0043] 5 , the first curved grid lines are defined as first curved sub-grid lines 21, and the first grid lines 10 include a first pad point-connecting grid line 11 connected to a first pad point 31 and a first main-grid-connecting grid line 12 connected to a first main grid 51. The first pad point-connecting grid line 11 and the first main-grid-connecting grid line 12 are adjacent to each other with a gap between them. The first curved sub-grid line 21 passes through the gap and curves toward the first main grid 51 and the first pad point 31, respectively, without contacting either the first main grid 51 or the first pad point 31. In other embodiments, the first pad point-connecting grid line 11 and / or the first main-grid-connecting grid line 12 may be omitted. However, by providing the first pad point-connecting grid line 11 and / or the first main-grid-connecting grid line 12, the grid lines can be arranged more uniformly and avoid current collection failure in some small areas.

[0044] 6 , the first curved grid lines are defined as second sub-curved grid lines 24, and the first grid lines 10 include second main-grid-connecting grid lines 14 connected to the first main grid 51, with gaps formed between the second main-grid-connecting grid lines 14 and the first pad points 31, and the second sub-curved grid lines 24 passing through the gaps and curved toward the first main grid 51 without contacting the first main grid 51. In other embodiments, additional pad point-connecting grid lines may be installed to achieve more uniform grid line distribution and avoid current collection failure in some small areas.

[0045] 7 , the first curved grid line is defined as the third sub-curved grid line 27, and the first grid line 10 includes the second pad point-connecting grid line 16 connected to the first pad point 31, with a gap formed between the second pad point-connecting grid line 16 and the first main grid 51, and the third sub-curved grid line 27 passing through the gap and curving toward the first pad point 31 without contacting the first pad point 31. In other embodiments, additional main grid-connecting grid lines may be installed to achieve a more uniform arrangement of the grid lines and avoid current collection failure in some small areas.

[0046] In an embodiment of the present invention, the length of the first curved grid lines can be determined according to the size of the area available for placement, and the first curved grid lines can be formed to extend divergently, so as to fully utilize the area available for current collection and further improve the current collection capability.

[0047] Furthermore, based on the above embodiment, the first curved grid line passes through at least one of the first grid lines 10. Multiple first grid lines 10 may be arranged in the area between the first pad point 31 and the first main grid 51 or in the area nearby. If multiple gaps are formed by the arrangement of the first grid lines 10, the first curved grid line can pass through the gaps in turn, and each time it passes through a gap, it will be formed to extend more divergently, thereby further improving the current collection capability. Example 3

[0048] 5 to 7, based on Example 2, the center line of the first connection electrode 41 and the center line of the first pad point 31 described in Example 5 are not on the same straight line.

[0049] In this embodiment, the center line of the first pad point 31 is aligned with the ground line of the second grid line 20, and the polarities of the first pad point 31 and the second grid line 20 are opposite. For example, when the first pad point 31 is positive, the second grid line 20 is negative. Therefore, by offsetting the center line of the first connection electrode 41 from the center line of the first pad point 31, i.e., offsetting the center line of the first connection electrode 41 from the ground line of the second grid line 20, the center line of the first connection electrode 41 can be aligned with the ground line of the first grid line 10. The first connection electrode 41 and the first grid line 10 have the same polarity. This achieves the goal of more uniformly distributing grid lines of opposite polarity in the area adjacent to the first pad point 31, further improving current collection capability. Example 4

[0050] Referring to Figure 9, based on Example 2, the electrode structure described in Example 4 further includes a third grid line 18 connecting the first main grid 51 and the first pad point 31, respectively, the third grid line 18 is installed adjacent to the first connection electrode 41, and the width of the third grid line 18 is smaller than the width of the first connection electrode 41.

[0051] In an embodiment of the present invention, the first connection electrode 41 is usually not in contact with the substrate of a back-contact cell. In this case, the photo-generated electron-holes in the area where the first connection electrode 41 is located cannot be efficiently collected. Therefore, the third grid lines 18 are provided in the area adjacent to the first connection electrode 41, so that the third grid lines 18 can be in contact with the substrate, thereby further enhancing the current collection capability. Example 5

[0052] Referring to FIG. 10, based on the first embodiment, the second grid lines 20 according to the fifth embodiment are covered with a first insulating material 62 in partial regions located on the center lines of the first pad points 31 .

[0053] The first insulating material 62 may be covered with an insulating adhesive, and the second grid lines 20 are covered with the insulating adhesive only in the partial area located on the center line of the first pad point 31, so that the production cost is not excessively increased. Of course, the first insulating material 62 may be in other embodiments as long as it can achieve the purpose of insulation.

[0054] During ribbon welding, the insulating effect of the first insulating material 62 prevents the second grid line 20 from contacting the ribbon in a partial region located on the center line of the first pad point 31, thereby effectively avoiding the occurrence of a short circuit. The first insulating material 62 is fabricated after the first pad point 31 and the first main grid 51 are formed, and does not affect the selection of electrode materials for the first pad point 31 and the first main grid 51. Example 6

[0055] Referring to FIG. 4, based on Example 1, the electrode structure described in Example 6 is: a second main grid 52 disposed near a second edge of the back-contact cell opposite the first edge and connected to the second grid line 20; The second pad point is 32, a second connection electrode (42) connecting the second main grid (52) and the second pad point (32), The distance between the second pad point 32 and the second edge is greater than the distance between the second main grid 52 and the second edge.

[0056] 4, the first edge refers to the leftmost edge of the back-contact battery, and the second edge refers to the rightmost edge of the back-contact battery. Similarly, multiple pad points are provided between the first pad point 31 and the second pad point 32, and these pad points may be aligned with the main grid of the same polarity.

[0057] The distance between the second pad point 32 and the second edge is greater than the distance between the second major grid 52 and the second edge. For example, referring to Figure 4, the distance between the leftmost side of the second pad point 32 and the leftmost edge of the back-contacted cell is greater than the distance between the leftmost side of the second major grid 52 and the leftmost edge of the back-contacted cell.

[0058] In this embodiment, the distance between the second major grid 52 and the second edge is 0.01 mm to 3 mm, which refers to the distance between the edge of the second major grid 52 closest to the second edge and the second edge. For example, the distance between the second major grid 52 and the second edge is 0.05 mm, 1 mm, 2 mm, 3 mm, or another parameter value between 0.01 mm and 3 mm. The distance between the second pad point 32 and the second edge is 1 mm to 20 mm, which refers to the distance between the edge of the second pad point 32 closest to the second edge and the second edge. For example, the distance between the second pad point 32 and the second edge is 1 mm, 5 mm, 10 mm, 20 mm, or another parameter value between 1 mm and 20 mm, but the distance between the second pad point 32 and the second edge is greater than the distance between the second major grid 52 and the second edge.

[0059] In this embodiment, the second pad point 32 is located away from the second main grid 52, and the connection between the second pad point 32 and the second main grid 52 is realized by the connection action of the second connecting electrode 42. Since the second main grid 52 is located at the second edge of the back-contacted battery, the second pad point 32 is far away from the second edge of the back-contacted battery. In the current collection process, the second grid line 20 collects the current in the second polarity region, and then transmits the collected current to the second pad point 32 and further from the second pad point 32 to the second main grid 52 via the second connecting electrode 42 to complete the current collection. Both edges of the back-contact cells are equipped with pads, main grids, and connecting electrodes connecting the pads and the main grids. Compared to the first electrode pattern design in the background art, this eliminates the need for large-area printing of insulating adhesive, allowing for the use of high-temperature paste for the pads and main grids, reducing costs and ensuring reliability. Furthermore, the pads and main grids do not require excessive height, reducing paste consumption. The elimination of large-area printing of insulating adhesive eliminates the problem of poor adhesion with some pastes, making mass production easier. Compared to the second electrode pattern design in the background art, the main grids are located at the edges of the back-contact cells, and the pads are farther away from the edges of the back-contact cells, avoiding stress concentration during the welding process and improving module yield and reliability. Compared to the third electrode pattern design in the background art, photogenerated electrons and holes can reach the isomer region without traveling long distances to collect current, fully ensuring higher photoelectric conversion efficiency. Example 7

[0060] Based on Example 6, the first grid lines 10 in Example 7 include second curved grid lines located between the second main grid 52 and the second pad point 32, and the second curved grid lines are curved toward the second main grid 52 and the second pad point 32, respectively, and are not in contact with either the second main grid 52 or the second pad point 32; alternatively, the second curved grid lines are curved toward the second main grid 52 and are not in contact with the second main grid 52; or the second curved grid lines are curved toward the second pad point 32 and are not in contact with the second pad point 32.

[0061] 5 , the second curved grid lines are defined as the fourth sub-curved grid lines 13, and the second grid lines 20 include the third pad point-connecting grid lines 22 connected to the second pad points 32 and the third main-grid-connecting grid lines 23 connected to the second main grid 52. The third pad point-connecting grid lines 22 and the third main-grid-connecting grid lines 23 are adjacent to each other, forming a gap between them. The fourth sub-curved grid lines 13 pass through the gap and curve toward the second main grid 52 and the second pad points 32, respectively, without contacting either the second main grid 52 or the second pad points 32. In other embodiments, the third pad point-connecting grid lines 22 and / or the third main-grid-connecting grid lines 23 may be omitted. However, by providing the third pad point-connecting grid lines 22 and / or the third main-grid-connecting grid lines 23, the grid lines can be arranged more uniformly and current collection failures in some small areas can be avoided.

[0062] 6 , the second curved grid lines are defined as fifth sub-curved grid lines 15, and the second grid lines 20 include fourth pad point-connecting grid lines 25 connected to second pad points 32 and fourth main grid-connecting grid lines 26 connected to second main grid 52, where the fourth pad point-connecting grid lines 25 and the fourth main grid-connecting grid lines 26 are adjacent to each other with a gap between them, and the fifth sub-curved grid line 15 passes through the gap and curves toward the second main grid 52 without contacting the second main grid 52. In other embodiments, the fourth pad point-connecting grid lines 25 and / or the fourth main grid-connecting grid lines 26 may be omitted, but providing the fourth pad point-connecting grid lines 25 and / or the fourth main grid-connecting grid lines 26 can make the grid lines more uniform and avoid current collection failure in some small areas.

[0063] 7 , the second curved grid line is defined as the sixth sub-curved grid line 17, and the second grid line 20 includes the fifth pad point-connecting grid line 28 that connects to the second pad point 32. A gap is formed between the fifth pad point-connecting grid line 28 and the second main grid 52, and the sixth sub-curved grid line 17 passes through the gap and curves toward the second pad point 32 without contacting the second pad point 32. In other embodiments, additional main grid-connecting grid lines may be installed to achieve more uniform grid line distribution and avoid current collection failure in some small areas.

[0064] In an embodiment of the present invention, the length of the second curved grid lines can be determined according to the size of the area available for placement, and the second curved grid lines can be formed to extend divergently, so that the area available for current collection can be fully utilized and the current collection capability can be further improved.

[0065] Furthermore, based on the above embodiment, the second curved grid line passes through at least one of the second grid lines 20. Multiple second grid lines 20 may be arranged in the area between the second pad point 32 and the second main grid 52 or in the area nearby. If multiple gaps are formed by the arrangement of the second grid lines 20, the second curved grid line can pass through the gaps in sequence, and each time it passes through a gap, it is further formed to extend divergently, thereby further improving the current collection capability.

[0066] In combination with Example 2, the arrangement of the first curved grid lines and the second curved grid lines at both edges of the back-contact battery may be different, and the arrangement of the first curved grid lines and the second curved grid lines may be selected according to the actual situation. For example, referring to Figure 8, the first curved grid lines are not arranged at the first edge of the back-contact battery, but the second curved grid lines are arranged at the second edge of the back-contact battery, and the second curved grid lines are curved toward the second main grid 52 and the second pad point 32, respectively. Example 8

[0067] 5 to 7, based on Example 7, the center line of the second connection electrode 42 and the center line of the second pad point 32 are on the same straight line in Example 8.

[0068] In this embodiment, the center line of the second pad point 32 is aligned with the ground line of the second grid line 20, and the second pad point 32 and the second grid line 20 have the same polarity. For example, if the second pad point 32 has a negative polarity, the second grid line 20 also has a negative polarity. Therefore, by aligning the center line of the second connection electrode 42 and the center line of the second pad point 32 on the same straight line, the center line of the second connection electrode 42 can be aligned with the ground line of the second grid line 20, and the second connection electrode 42 and the second grid line 20 have the same polarity. This achieves the goal of more uniformly distributing grid lines of opposite polarity in the area adjacent to the second pad point 32, further improving current collection capability. Example 9

[0069] Based on Example 7, the electrode structure described in Example 9 further includes a fourth grid line 29 connecting the second main grid 52 and the second pad point 32, respectively, the fourth grid line 29 is installed adjacent to the second connecting electrode 42, and the width of the fourth grid line 29 is smaller than the width of the second connecting electrode 42.

[0070] In an embodiment of the present invention, the second connection electrode 42 is usually not in contact with the substrate of a back-contact cell. In this case, the photo-generated electrons and holes in the area where the second connection electrode 42 is located cannot be efficiently collected. Therefore, the fourth grid line 29 is provided in the area adjacent to the second connection electrode 42, so that the fourth grid line 29 can be in contact with the substrate, thereby further enhancing the current collection capability. Example 10

[0071] Based on the sixth embodiment, the first grid line 10 according to the tenth embodiment is covered with a second insulating material 61 in a partial region located on the center line of the second pad point 32 .

[0072] The second insulating material 61 may be covered with an insulating adhesive, and the first grid lines 10 are covered with the insulating adhesive only in the partial area located on the center line of the second pad point 32, thereby preventing excessive increases in production costs. Naturally, other embodiments of the second insulating material 61 may be adopted as long as they can achieve the purpose of insulation.

[0073] During ribbon welding, the insulating effect of the second insulating material 61 prevents the first grid line 10 from contacting the ribbon in a partial region located on the center line of the second pad point 32, thereby effectively avoiding the occurrence of a short circuit. The second insulating material 61 is fabricated after the second pad point 32 and the second main grid 52 are formed, and does not affect the selection of electrode materials for the second pad point 32 and the second main grid 52.

[0074] Based on the above-mentioned Examples 1 to 10, model calculations are now performed.

[0075] FIG. 11 shows an edge model diagram based on the electrode structure of FIG. 2, FIG. 12 shows an edge model diagram based on the electrode structure of FIG. 3, FIG. 13 shows an edge model diagram based on the electrode structure of FIG. 4, and FIG. 14 shows an edge model diagram based on the electrode structures of FIGS. 5 to 9.

[0076] The following table can be created: [Table 1]

[0077] Battery conversion efficiency is an important performance evaluation index for back-contact batteries; the higher the efficiency, the better the performance. In the industry, every 0.1% increase is considered a significant breakthrough. As can be seen from the table, adopting the solution shown in Figure 3 solves the module yield and reliability issues, but at the cost of a significant performance loss of 0.789%. Adopting the solution shown in Figure 4 of the present invention improves both module yield and reliability while reducing the efficiency loss to 0.12%. Adopting the optimized solutions shown in Figures 5 to 9 of the present invention reduces the efficiency loss to 0.003%. Since the current test reproducibility of back-contact battery conversion efficiency is approximately ±0.05%, this efficiency loss is so low that it can be ignored. Example 11

[0078] This Example 11 provides a back-contact cell including the electrode structure described in Examples 1 to 10, wherein the electrode structure is disposed on the backlight surface of the back-contact cell.

[0079] In the electrode structure provided in this embodiment, the first pad point 31 is located away from the first main grid 51, and the connection between the first pad point 31 and the first main grid 51 is realized by the connection action of the first connecting electrode 41. Since the first main grid 51 is located at the first edge of the back-contacted battery, the first pad point 31 is far away from the first edge of the back-contacted battery. In the current collection process, the first grid line 10 collects the current in the first polarity region, and then the first grid line 10 transmits the collected current to the first pad point 31 and then from the first pad point 31 to the first main grid 51 via the first connecting electrode 41 to complete the current collection. Compared to the first electrode pattern design of the background art, the electrode structure of the present invention eliminates the need for large-area printing of insulating adhesive, allowing the first pad point 31 and first main grid 51 to use high-temperature paste, reducing costs and ensuring reliability. Furthermore, the first pad point 31 and first main grid 51 do not require excessive height, reducing paste consumption. The elimination of large-area printing of insulating adhesive eliminates the problem of poor adhesion with some pastes, easing mass production. Compared to the second electrode pattern design of the background art, the first main grid 51 is located at the first edge of the back-contact cell, and the first pad point 31 is farther away from the first edge of the back-contact cell, avoiding stress concentration during the welding process and improving module yield and reliability. Compared to the third electrode pattern design of the background art, photogenerated electrons and holes can reach the isomer region without traveling long distances to achieve current collection, fully ensuring higher photoelectric conversion efficiency. Example 12

[0080] This Example 12 provides a back-contact cell module including the back-contact cells described in Example 11.

[0081] In the electrode structure provided in this embodiment, the first pad point 31 is located away from the first main grid 51, and the connection between the first pad point 31 and the first main grid 51 is realized by the connection action of the first connecting electrode 41. Since the first main grid 51 is located at the first edge of the back-contacted battery, the first pad point 31 is far away from the first edge of the back-contacted battery. In the current collection process, the first grid line 10 collects the current in the first polarity region, and then the first grid line 10 transmits the collected current to the first pad point 31 and then from the first pad point 31 to the first main grid 51 via the first connecting electrode 41 to complete the current collection. Compared to the first electrode pattern design of the background art, the electrode structure of the present invention eliminates the need for large-area printing of insulating adhesive, allowing the first pad point 31 and first main grid 51 to use high-temperature paste, reducing costs and ensuring reliability. Furthermore, the first pad point 31 and first main grid 51 do not require excessive height, reducing paste consumption. The elimination of large-area printing of insulating adhesive eliminates the problem of poor adhesion with some pastes, easing mass production. Compared to the second electrode pattern design of the background art, the first main grid 51 is located at the first edge of the back-contact cell, and the first pad point 31 is farther away from the first edge of the back-contact cell, avoiding stress concentration during the welding process and improving module yield and reliability. Compared to the third electrode pattern design of the background art, photogenerated electrons and holes can reach the isomer region without traveling long distances to achieve current collection, fully ensuring higher photoelectric conversion efficiency. Example 13

[0082] This Example 13 provides a back-contact battery system including the back-contact battery module described in Example 12.

[0083] In the electrode structure provided in this embodiment, the first pad point 31 is located away from the first main grid 51, and the connection between the first pad point 31 and the first main grid 51 is realized by the connection action of the first connecting electrode 41. Since the first main grid 51 is located at the first edge of the back-contacted battery, the first pad point 31 is far away from the first edge of the back-contacted battery. In the current collection process, the first grid line 10 collects the current in the first polarity region, and then the first grid line 10 transmits the collected current to the first pad point 31 and then from the first pad point 31 to the first main grid 51 via the first connecting electrode 41 to complete the current collection. Compared to the first electrode pattern design of the background art, the electrode structure of the present invention eliminates the need for large-area printing of insulating adhesive, allowing the first pad point 31 and first main grid 51 to use high-temperature paste, reducing costs and ensuring reliability. Furthermore, the first pad point 31 and first main grid 51 do not require excessive height, reducing paste consumption. The elimination of large-area printing of insulating adhesive eliminates the problem of poor adhesion with some pastes, easing mass production. Compared to the second electrode pattern design of the background art, the first main grid 51 is located at the first edge of the back-contact cell, and the first pad point 31 is farther away from the first edge of the back-contact cell, avoiding stress concentration during the welding process and improving module yield and reliability. Compared to the third electrode pattern design of the background art, photogenerated electrons and holes can reach the isomer region without traveling long distances to achieve current collection, fully ensuring higher photoelectric conversion efficiency.

[0084] The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall all be included in the protection scope of the present invention.

Claims

1. a first polarity region; a second polarity region; A first edge; first grid lines collecting the first polarity regions and extending along a first direction; second grid lines collecting the second polar regions and extending along the first direction; a first main grid disposed near the first edge and connected to the first grid line; A plurality of first pad points; a plurality of first connection electrodes connecting the first main grid and the first pad points; a distance between the first pad point and the first edge is greater than a distance between the first major grid and the first edge; a first curved grid line located between the first major grid point and the first pad point is connected to the second grid line; The first curved grid lines are a portion of the pad overlaps the first pad point in a second direction perpendicular to the first direction so as not to contact both the first pad point and the first main grid; a collecting portion that is not in contact with either the first pad point or the first main grid and that collects the second polarity region; 1. An electrode structure for a back contact battery, comprising:

2. The electrode structure for a back-contact battery as claimed in claim 1 , wherein the first curved grid lines pass through at least one of the first grid lines.

3. 2. The electrode structure of claim 1, wherein the center line of the first connection electrode and the center line of the first pad point are not on the same line.

4. 2. The electrode structure of claim 1, further comprising a third grid line connecting the first main grid and the first pad point, the third grid line being disposed adjacent to the first connection electrode, and the width of the third grid line being smaller than the width of the first connection electrode.

5. The electrode structure of a back-contact battery according to claim 1 , wherein the second grid lines are covered with a first insulating material in partial regions located on the centerlines of the first pad points.

6. 2. The electrode structure of a back-contact battery as claimed in claim 1, wherein the distance between the first main grid and the first edge is 0.01 mm to 3 mm.

7. The electrode structure of claim 6, wherein the distance between the first pad point and the first edge is 1 mm to 20 mm.

8. a second main grid disposed near a second edge of the back-contact cell opposite the first edge and connected to the second grid line; a plurality of second pad points; a plurality of second connection electrodes connecting the second main grid and the second pad points; 2. The electrode structure of claim 1, wherein the distance between the second pad point and the second edge is greater than the distance between the second main grid and the second edge.

9. 9. The electrode structure of claim 8, wherein the first grid lines include second curved grid lines located between the second major grid and the second pad point, the second curved grid lines curved toward the second major grid and the second pad point, respectively, and not in contact with either the second major grid or the second pad point, or the second curved grid lines curved toward the second major grid and not in contact with the second major grid, or the second curved grid lines curved toward the second pad point and not in contact with the second pad point.

10. 10. The electrode structure of a back-contact battery as claimed in claim 9, wherein the second curved grid lines pass through at least one of the second grid lines.

11. The electrode structure of claim 9 , wherein the center line of the second connection electrode and the center line of the second pad point are aligned on the same line.

12. 10. The electrode structure of claim 9, further comprising a fourth grid line connecting the second main grid and the second pad point, the fourth grid line being disposed adjacent to the second connection electrode, and the width of the fourth grid line being smaller than the width of the second connection electrode.

13. The electrode structure of a back-contact battery according to claim 8 , wherein the first grid lines are covered with a second insulating material in partial regions located on the centerlines of the second pad points.

14. 9. The electrode structure of a back-contact battery as claimed in claim 8, wherein the distance between the second main grid and the second edge is 0.01 mm to 3 mm.

15. The electrode structure of claim 14, wherein the distance between the second pad point and the second edge is 1 mm to 20 mm.

16. A back-contact battery comprising the electrode structure of claim 1, wherein the electrode structure is disposed on a backlight surface of the back-contact battery.

17. A back-contact battery module comprising the back-contact battery of claim 16.

18. A back-contact battery system comprising the back-contact battery module of claim 17.

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