Electrode structure of a rear contact battery, rear contact battery, rear contact battery module, and rear contact battery 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 belongs to the technical field of solar cells, and particularly relates 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 Art

[0002] A solar cell is a semiconductor device that converts light energy into electrical energy. Lower manufacturing costs and higher energy conversion efficiency have always been the goals pursued in the solar cell industry. In current ordinary solar cells, the emitter contact electrode and the base contact electrode are respectively on the front and back surfaces of the cell sheet. The front surface of the cell is the light-receiving surface. Due to the coverage of the metal emitter contact electrode on the front, inevitably, a part of the incident sunlight is reflected and shielded by the metal electrode, causing some light loss. The coverage area of the front metal electrode of a general crystalline silicon solar cell is about 7%. By reducing the front coverage of the metal electrode, the energy conversion efficiency of the cell can be directly improved.

[0003] In response to the above, back contact solar cells have been proposed in the industry. A back contact solar cell is a cell in which both the emitter contact electrode and the base contact electrode are arranged on the back (non-light-receiving surface) of the cell. Since there is no shielding by the metal electrode on the light-receiving surface of the cell, the short-circuit current of the cell sheet can be effectively increased. Also, on the back, it is possible to reduce the series resistance and improve the fill factor with wider metal grid lines. Moreover, such a cell without front shielding not only has high conversion efficiency but also looks more beautiful, and the assembly of the module with all-back electrodes is also easier.

[0004] The electrode pattern design of a back contact solar cell is the core technology. There are the following three conventional electrode pattern designs for back contact solar cells.

[0005] 1. Referring to Figure 1, insulating adhesive 3 is printed onto dissimilar electrodes to form insulation, while the same-sex electrodes are exposed. Subsequently, pad points 1 and busbars 2 are printed to bring the same-sex electrodes into contact. However, insulating adhesive 3 cannot withstand high temperatures, and pad points 1 and busbars 2 are formed by post-printing. Therefore, only low-temperature pastes can be used for pad points 1 and busbars 2, increasing costs, and the use of low-temperature pastes presents reliability issues. To form good insulation, insulating adhesive 3 has a height of approximately 30 μm, and pad points 1 and busbars 2 need to be taller than 30 μm to avoid disconnection. This increases paste consumption and further increases costs. In addition, insulating adhesive 3 and some pastes have problems such as low adhesion, making mass production a significant challenge.

[0006] 2. Referring to Figure 2, the fine grid 4 is cut at dissimilar pad points 5 and busbars 6, and the pad points 5 and busbars 6 at the edge are located at the very edge of the silicon wafer. Since the pad points 5 and busbars 6 are at the edge of the silicon wafer, in the module fabrication process the ribbon also needs to cover the edge of the silicon wafer. A large number of microcracks exist at the edge of the silicon wafer, and stress concentration during the ribbon welding process can cause the silicon wafer to fracture, leading to a decrease in module yield and reduced module reliability.

[0007] 3. Referring to Figure 3, the fine grid 7 is cut at isomorphic pad points 8 and busbars 9, the outer pad points 8 and busbars 9 are a certain distance away from the belly edge of the silicon wafer, and the area around the outer pad points 8 and busbars 9 is set to the same polarity. The third design solves the problems present in the first and second designs described above, however, photogenerated electron holes need to diffuse into isomorphic regions to form efficient collection. In the third design, the outer photogenerated electron holes need to travel distances on the order of millimeters or even centimeters to reach the isomorphic regions. Recombination losses during long-distance diffusion reduce the short-circuit current and increase the series resistance, causing losses in the curve factor and further resulting in very low photoelectric conversion performance.

[0008] Therefore, in order to solve the above problems, designing the electrode structure of a back-contact battery, a back-contact battery, a back-contact battery module, and a back-contact battery system is always an important issue that those skilled in the art should study. [Overview of the Initiative]

[0009] This invention provides an electrode structure for a back-contact solar cell to solve the technical problems of conventional 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 the first polarity region, A second grid line for collecting the second polarity region, A first main grid is installed on the side of the rear contact battery that is close to the first edge and connected to the first grid line, First pad point, The system includes a first connecting electrode that connects the first main grid and the first pad point, respectively. The present invention provides an electrode structure for a back-contact battery in which the distance between the first pad point and the first edge is greater than the distance between the first main grid and the first edge.

[0012] Furthermore, the second grid line includes a first curved grid line located between the first principal grid and the first pad point, wherein each of the first curved grid lines curves toward the first principal grid and the first pad point and does not contact the first principal grid and the first pad point, or the first curved grid line curves toward the first principal grid and does not contact the first principal grid, or the first curved grid line curves toward the first pad point and does not contact the first pad point.

[0013] Furthermore, the first curved grid line passes through at least one of the first grid lines.

[0014] Furthermore, the center line of the first connecting 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, the third grid line being installed adjacent to the first connecting electrode, and the width of the third grid line being smaller than the width of the first connecting electrode.

[0016] Furthermore, the second grid line is covered with the first insulating material in a portion of the region located at the center line of the first pad point.

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

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

[0019] Furthermore, the electrode structure is A second main grid is installed on the side of the rear contact battery that is closer to the second edge which is opposite to the first edge, and is connected to the second grid line, The second pad point, The system further includes a second connecting electrode that connects the second main grid and the second pad point, 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.

[0020] Furthermore, the first grid line includes second curved grid lines located between the second main grid and the second pad point. The second curved grid lines curve towards the second main grid and the second pad point respectively, and neither of them is in contact with the second main grid and the second pad point, or the second curved grid lines curve towards the second main grid and are not in contact with the second main grid, or the second curved grid lines curve towards the second pad point and are not in contact with the second pad point.

[0021] Furthermore, 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 fourth grid lines connecting the second main grid and the second pad point respectively. The fourth grid lines are installed adjacent to the second connection electrode, and the width of the fourth grid lines is smaller than the width of the second connection electrode.

[0024] Furthermore, the part of the first grid line located in the partial region on the center line of the second pad point is covered with a second insulating material.

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

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

[0027] The present invention includes the electrode structure as described above, and further provides a back contact battery in which the electrode structure is installed on the backlight surface of the back contact battery.

[0028] The present invention further provides a back contact cell module including the back contact cell described above.

[0029] The present invention further provides a back contact cell system including the back contact cell 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 connection electrode connecting the first main grid and the first pad point respectively, and realizes the collection of current. The electrode structure does not need to print an insulating adhesive in a large area, the first pad point is not installed on the first edge of the back contact cell together with the first main grid, and the photogenerated electron holes do not need to span a long distance to reach the opposite region. Thereby, the electrode structure can improve reliability, reduce costs, improve the yield of products, and ensure very excellent photoelectric conversion efficiency.

Brief Description of the Drawings

[0031] [Figure 1] It is a schematic diagram of a first electrode pattern design according to the prior art. [Figure 2] It is a schematic diagram of a second electrode pattern design according to the prior art. [Figure 3] It is a schematic diagram of a third electrode pattern design according to the prior art. [Figure 4] It is a schematic diagram of the electrode structure provided in an embodiment of the present invention. [Figure 5] It is a schematic diagram of an electrode structure provided in an embodiment of the present invention, in which a curved grid line extending toward each pad point and the main grid is provided. [Figure 6] It is a schematic diagram of an electrode structure provided in an embodiment of the present invention, in which a curved grid line extending toward the main grid is provided. [Figure 7] It is a schematic diagram of an electrode structure provided in an embodiment of the present invention, in which a curved grid line extending toward the pad point is provided. [Figure 8]This is a schematic diagram of an electrode structure having different grid line designs on the edges of both ends of a back-contact battery provided in an embodiment of the present invention. [Figure 9] This is a schematic diagram of an electrode structure provided with a third grid line and a fourth grid line as provided in an embodiment of the present invention. [Figure 10] This is a schematic diagram of an electrode structure provided with the first insulating material and the second insulating material provided in an embodiment of the present invention. [Figure 11] This is an edge model diagram of a second electrode pattern design related to the conventional technology. [Figure 12] This is an edge model diagram of a third electrode pattern design related to the conventional technology. [Figure 13] Figure 4 is an edge model diagram based on the electrode structure. [Figure 14] Figures 5 to 9 are edge model diagrams based on the electrode structure. [Modes for carrying out the invention]

[0032] To further clarify the object, technical solution, and advantages of the present invention, the present invention will be described in more detail below, with reference to the drawings and embodiments. It should be understood that the specific examples described herein are for interpretation purposes only and are not intended to limit the present invention.

[0033] The present invention provides an electrode structure for a back-contact battery including 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. The first grid line is for collecting current in a first polarity region, and current collection is achieved by merging with the first main grid through the first pad point and the first connecting electrode. The electrode structure does not require printing insulating adhesive over a large area, the first pad point is not located on the first edge of the back-contact battery together with the first main grid, and photogenerated electron holes do not need to travel long distances to reach the isopolar region. As a result, the electrode structure can improve reliability, reduce costs, improve product yield, and ensure very good photoelectric conversion efficiency. Example 1

[0034] Referring to Figure 4, this embodiment 1 is, A first grid line 10 for collecting the first polarity region, A second grid line 20 for collecting the second polarity region, A first main grid 51 is installed on the side of the rear contact battery that is close to the first edge and connected to the first grid line 10, The first pad point is 31, It includes a first connecting electrode 41 that connects the first main grid 51 and the first pad point 31, respectively. The electrode structure of the back contact battery is provided such that 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.

[0035] In embodiments of the present invention, the first grid line 10 is used to collect the current in the first polarity region, and the second grid line 20 is used to collect the current in the 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 electrode grid line for collecting the positive electrode current in the positive electrode region, the second grid line 20 is a negative electrode grid line for collecting the negative electrode current in the negative electrode region, or if the first grid line 10 is a negative electrode grid line for collecting the negative electrode current in the negative electrode region, the second grid line 20 is a positive electrode grid line for collecting the positive electrode current in the positive electrode region. Here, the positive electrode grid line is provided in the P-type doped region of the back contact battery, and the negative electrode grid line is provided in the N-type doped region of the back contact battery.

[0036] Referring to Figures 4 to 10, for ease of identification, the first grid line 10 in the blacked-out area has the same polarity, the second grid line 20 in the unblacked-out area has the same polarity, and the polarity of the first grid line 10 and the second grid line 20 are opposite. The first pad point 31, the first connecting electrode 41, and the first main grid 51 in the blacked-out area have the same polarity as the first grid line 10.

[0037] The first grid lines 10 and the second grid lines 20 are arranged alternately, 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 Figure 4, the first grid lines 10 and the second grid lines 20 are arranged alternately in the vertical direction, and both the first grid lines 10 and the second grid lines 20 are horizontal to the upper and lower edge lines of the back contact battery. The back contact battery is substantially rectangular, and a substantially rectangular back contact battery may be, for example, a square or another rectangle, and may have standard corners, truncated corners or rounded corners, which are determined according to the actual manufacturing requirements and are not specifically limited here. The number of the first grid lines 10 and the second grid lines 20 is determined according to the actual area size of the back contact battery, the width and distance of the first grid lines 10 and the second grid lines 20, and is not specifically limited here.

[0038] Furthermore, the first grid line 10 or the second grid line 20 is an aluminum grid line, a silver grid line, a copper grid line, or a silver-clad copper grid line. In embodiments of the present invention, it is understandable that the first grid line 10 and the second grid line 20 may be the same or different metal types of grid lines, for example, both the first grid line 10 and the second grid line 20 may be aluminum grid lines, or the first grid line 10 may be an aluminum grid line and the second grid line 20 may be a silver grid line. If the first grid line 10 or the second grid line 20 is an aluminum grid line or a silver grid line, the aluminum grid line or silver grid line is printed on the doped area of ​​the back contact battery by screen printing, and if the first grid line 10 or the second grid line 20 is a copper grid line, it is plated on the doped area of ​​the back contact battery by electroplating or vapor deposition, etc.

[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 Figure 4, the distance between the leftmost part of the first pad point 31 and the leftmost edge of the rear contact battery is greater than the distance between the leftmost part of the first main grid 51 and the leftmost edge of the rear contact battery.

[0040] In this embodiment, the distance between the first principal grid 51 and the first edge is 0.01 mm to 3 mm, where this refers to the distance between the edge closest to the first edge of the first principal grid 51 and the first edge. For example, the distance between the first principal grid 51 and the first edge is 0.05 mm, 1 mm, 2 mm, 3 mm, or other parameter values ​​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, where this 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 other parameter values ​​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 principal grid 51 and the first edge.

[0041] In an embodiment of the present invention, the first pad point 31 is positioned away from the first main grid 51, and the connection between the first pad point 31 and the first main grid 51 is achieved by the connection action of the first connecting electrode 41. Since the first main grid 51 is positioned on the first edge of the back contact battery, the first pad point 31 is far from the first edge of the back contact battery. In the current collection process, the first grid line 10 collects the current in the first polarity region, and the first grid line 10 further transmits the collected current to the first pad point 31, and further transmits it from the first pad point 31 to the first main grid 51 via the first connecting electrode 41, thereby completing the current collection. Compared to the first electrode pattern design of the background art, the electrode structure of the present invention does not require printing insulating adhesive over a large area, so high-temperature paste can be selected for the first pad point 31 and the first main grid 51, reducing costs and ensuring reliability. Furthermore, since the first pad point 31 and the first main grid 51 do not require excessive height, paste consumption is reduced, and because it is not necessary to print insulating adhesive over a large area, the problem of poor adhesion with some pastes is eliminated, and the difficulty of mass production is reduced. Compared to the second electrode pattern design of the background art, since the first main grid 51 is located at the first edge of the back contact battery and the first pad point 31 is far from the first edge of the back contact battery, the problem of stress concentration in the welding process can be avoided, improving module yield and module reliability. Compared to the third electrode pattern design of the background art, since photogenerated electron holes can reach isomer regions without having to travel long distances to achieve current collection, a higher photoelectric conversion efficiency is sufficiently ensured. Example 2

[0042] Based on Embodiment 1, the second grid line 20 described in Embodiment 2 includes a first curved grid line located between the first main grid 51 and the first pad point 31, wherein the first curved grid line is curved toward the first main grid 51 and the first pad point 31 respectively and does not contact the first main grid 51 and the first pad point 31, or the first curved grid line is curved toward the first main grid 51 and does not contact the first main grid 51, or the first curved grid line is curved toward the first pad point 31 and does not contact the first pad point 31.

[0043] Referring to Figure 5, the first curved grid line is defined as the first sub-curved grid line 21, and the first grid line 10 includes the first pad point connecting grid line 11 connected to the first pad point 31 and the first main grid connecting grid line 12 connected to the first main grid 51, wherein the first pad point connecting grid line 11 and the first main grid connecting grid line 12 are installed adjacent to each other, with a gap between them, and the first sub-curved grid line 21 passes through this gap, curving toward the first main grid 51 and the first pad point 31 respectively, and neither is in contact with the first main grid 51 and the first pad point 31. In other embodiments, the installation of the first pad point connecting grid line 11 and / or the first main grid connecting grid line 12 may be omitted, but by installing the first pad point connecting grid line 11 and / or the first main grid connecting grid line 12, the grid lines can be more uniformly arranged, and it is possible to avoid the inability to collect current in some small areas.

[0044] Referring to Figure 6, the first curved grid line is defined as the second sub-curved grid line 24, and the first grid line 10 includes the second main grid connecting grid line 14 connected to the first main grid 51, with a gap formed between the second main grid connecting grid line 14 and the first pad point 31, the second sub-curved grid line 24 passing through the gap and curving toward the first main grid 51, and not in contact with the first main grid 51. In other embodiments, additional pad point connecting grid lines may be installed to achieve a more uniform arrangement of grid lines and to avoid the inability to collect current in some small areas.

[0045] Referring to Figure 7, the first curved grid line is defined as the third sub-curved grid line 27, and the first grid line 10 includes a 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, the third sub-curved grid line 27 passing through the gap and curving toward the first pad point 31, and not in contact with the first pad point 31. In other embodiments, main grid connecting grid lines may be added to achieve a more uniform arrangement of grid lines and to avoid the inability to collect current in some small areas.

[0046] In embodiments of the present invention, the length of the first curved grid line can be determined according to the size of the area where it can be placed, and the first curved grid line is formed to extend divergently, making full use of the area where current can be collected and further enhancing 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 region between the first pad point 31 and the first main grid 51 or in the vicinity region, and 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 sequence, and each time it passes through a gap, it is formed to extend further divergently, thereby further enhancing the current collection capability. Example 3

[0048] Referring to Figures 5 to 7, and based on Example 2, the center line of the first connecting 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 an embodiment of the present invention, the center line of the first pad point 31 lies on the installation 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, if the first pad point 31 is positively polarized, the second grid line 20 is negatively polarized. Therefore, by offsetting the center line of the first connecting electrode 41 from the center line of the first pad point 31, that is, by offsetting the center line of the first connecting electrode 41 from the installation line of the second grid line 20, it is possible to set the center line of the first connecting electrode 41 on the installation line of the first grid line 10. The first connecting electrode 41 and the first grid line 10 have the same polarity, thereby achieving the objective of more uniformly distributing grid lines of opposite polarity in the region adjacent to the first pad point 31, and further enhancing the current collection capability. Example 4

[0050] Referring to Figure 9, and 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, wherein the third grid line 18 is installed adjacent to the first connecting electrode 41, and the width of the third grid line 18 is smaller than the width of the first connecting electrode 41.

[0051] In embodiments of the present invention, the first connecting electrode 41 does not normally contact the substrate of the back-contact battery. In this case, photo-generated electron holes in the region where the first connecting electrode 41 is located cannot be efficiently collected. Therefore, a third grid line 18 is placed in a region adjacent to the first connecting electrode 41, and the third grid line 18 can contact the substrate, thereby further enhancing the current collection capability. Example 5

[0052] Referring to Figure 10, and based on Example 1, the second grid line 20 described in Example 5 is covered with the first insulating material 62 in a portion area located on the center line of the first pad point 31.

[0053] The first insulating material 62 may be covered with an insulating adhesive, and since the second grid line 20 is covered with the insulating adhesive only in a portion of the area located on the center line of the first pad point 31, the product cost will not be excessively increased. Of course, the first insulating material 62 may be in other embodiments as long as the purpose of insulation is achieved.

[0054] When performing ribbon welding, the insulating effect of the first insulating material 62 prevents the second grid line 20 from coming into contact with the ribbon in a portion of the region located on the center line of the first pad point 31, thereby effectively avoiding the occurrence of a short circuit. Furthermore, the first insulating material 62 is manufactured 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 Figure 4, the electrode structure described in Example 6, based on Example 1, is A second main grid 52 is installed on the side of the rear contact battery that is closer to the second edge which is opposite to the first edge, and is connected to the second grid line 20, The second pad point 32, The system further includes a second connecting electrode 42 that connects the second main grid 52 and the second pad point 32, respectively. 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] Referring to Figure 4, the first edge refers to the leftmost part of the rear contact battery, and the second edge refers to the rightmost part of the rear contact battery. Similarly, multiple pad points are provided between the first pad point 31 and the second pad point 32, and the pad points in this portion may be set on the same straight line as 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 main grid 52 and the second edge. For example, referring to Figure 4, the distance between the leftmost part of the second pad point 32 and the leftmost edge of the rear contact battery is greater than the distance between the leftmost part of the second main grid 52 and the leftmost edge of the rear contact battery.

[0058] In this embodiment, the distance between the second principal grid 52 and the second edge is 0.01 mm to 3 mm, where this refers to the distance between the edge closest to the second edge of the second principal grid 52 and the second edge itself. For example, the distance between the second principal grid 52 and the second edge is 0.05 mm, 1 mm, 2 mm, 3 mm, or other parameter values ​​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, where this refers to the distance between the edge closest to the second edge of the second pad point 32 and the second edge itself. For example, the distance between the second pad point 32 and the second edge is 1 mm, 5 mm, 10 mm, 20 mm, or other parameter values ​​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 principal grid 52 and the second edge.

[0059] In an embodiment of the present invention, the second pad point 32 is positioned away from the second main grid 52, and the connection between the second pad point 32 and the second main grid 52 is achieved by the connecting action of the second connecting electrode 42. Since the second main grid 52 is positioned at the second edge of the back contact battery, the second pad point 32 is far from the second edge of the back contact battery. In the current collection process, the second grid line 20 collects the current in the second polarity region, and the second grid line 20 further transmits the collected current to the second pad point 32, and then transmits it from the second pad point 32 to the second main grid 52 via the second connecting electrode 42, thereby completing the current collection. The edges of both ends of the back contact battery are equipped with pad points, a main grid, and connecting electrodes that connect the pad points and the main grid, respectively. Compared to the first electrode pattern design of the background technology, it is not necessary to print insulating adhesive over a large area, so high-temperature paste can be selected for the pad points and main grid, reducing costs and ensuring reliability. Also, since the pad points and main grid do not require excessive height, paste consumption is reduced, and because it is not necessary to print insulating adhesive over a large area, the problem of poor adhesion with some paste is eliminated, and the difficulty of mass production is reduced. Compared to the second electrode pattern design of the background technology, the main grid is located at the edge of the back contact battery and the pad points are far from the edge of the back contact battery, so the problem of stress concentration in the welding process can be avoided, improving module yield and module reliability. Compared to the third electrode pattern design of the background technology, photogenerated electron holes can reach the isomorphic region without having to travel long distances to achieve current collection, thus ensuring a higher photoelectric conversion efficiency. Example 7

[0060] Based on Example 6, the first grid line 10 described in Example 7 includes a second curved grid line located between the second main grid 52 and the second pad point 32, wherein the second curved grid line curves toward the second main grid 52 and the second pad point 32 respectively and does not contact the second main grid 52 and the second pad point 32, or the second curved grid line curves toward the second main grid 52 and does not contact the second main grid 52, or the second curved grid line curves toward the second pad point 32 and does not contact the second pad point 32.

[0061] Referring to Figure 5, the second curved grid line is defined as the fourth sub-curved grid line 13, and the second grid line 20 includes the third pad point connecting grid line 22 connected to the second pad point 32, and the third main grid connecting grid line 23 connected to the second main grid 52, wherein the third pad point connecting grid line 22 and the third main grid connecting grid line 23 are installed adjacent to each other, with a gap between them, and the fourth sub-curved grid line 13 passes through this gap, curving toward the second main grid 52 and the second pad point 32 respectively, and neither is in contact with the second main grid 52 and the second pad point 32. In other embodiments, the installation of the third pad point connecting grid line 22 and / or the third main grid connecting grid line 23 may be omitted, but by installing the third pad point connecting grid line 22 and / or the third main grid connecting grid line 23, the grid lines can be more uniformly arranged, and the inability to collect current in some small areas can be avoided.

[0062] Referring to Figure 6, the second curved grid line is defined as the fifth sub-curved grid line 15, and the second grid line 20 includes the fourth pad point connecting grid line 25 connected to the second pad point 32, and the fourth main grid connecting grid line 26 connected to the second main grid 52, wherein the fourth pad point connecting grid line 25 and the fourth main grid connecting grid line 26 are installed adjacent to each other, with a gap between them, and the fifth sub-curved grid line 15 passes through this gap and curves toward the second main grid 52, without contacting the second main grid 52. In other embodiments, the installation of the fourth pad point connecting grid line 25 and / or the fourth main grid connecting grid line 26 may be omitted, but by installing the fourth pad point connecting grid line 25 and / or the fourth main grid connecting grid line 26, the grid lines can be more uniformly arranged, and current collection can be avoided in some small areas.

[0063] Referring to Figure 7, the second curved grid line is defined as the sixth sub-curved grid line 17, and the second grid line 20 includes a fifth pad point connecting grid line 28 connected to the second pad point 32, with a gap formed between the fifth pad point connecting grid line 28 and the second main grid 52, the sixth sub-curved grid line 17 passing through the gap and curving toward the second pad point 32, and not in contact with the second pad point 32. In other embodiments, main grid connecting grid lines may be added to achieve a more uniform arrangement of grid lines and to avoid the inability to collect current in some small areas.

[0064] In embodiments of the present invention, the length of the second curved grid line can be determined according to the size of the area where it can be placed, and the second curved grid line is formed to extend divergently, making full use of the area where current can be collected and further enhancing the current collection capability.

[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 region between the second pad point 32 and the second main grid 52 or in the vicinity region, and 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 enhancing the current collection capability.

[0066] When combined with Example 2, the installation methods of the first curved grid line and the second curved grid line may differ at the edges of both ends of the rear contact battery, and the installation methods of the first curved grid line and the second curved grid line can be selected according to the actual situation. For example, referring to Figure 8, the first curved grid line is not installed at the first edge of the rear contact battery, but the second curved grid line is installed at the second edge of the rear contact battery, and the second curved grid line curves toward the second main grid 52 and the second pad point 32, respectively. Example 8

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

[0068] In an embodiment of the present invention, the center line of the second pad point 32 lies on the installation 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 is negative polarity, then the second grid line 20 is negative polarity. Therefore, by setting the center line of the second connecting electrode 42 and the center line of the second pad point 32 on the same straight line, it is possible to set the center line of the second connecting electrode 42 on the installation line of the second grid line 20. Since the second connecting electrode 42 and the second grid line 20 have the same polarity, the objective of more uniformly distributing grid lines of opposite polarity in the region adjacent to the second pad point 32 is achieved, further enhancing the 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, wherein 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 embodiments of the present invention, the second connecting electrode 42 does not normally contact the substrate of the back-contact battery. In this case, photogenerated electron holes in the region where the second connecting electrode 42 is located cannot be efficiently collected. Therefore, a fourth grid line 29 is installed in a region adjacent to the second connecting electrode 42, and the fourth grid line 29 can contact the substrate, thereby further enhancing the current collection capability. Example 10

[0071] Based on Example 6, the first grid line 10 described in Example 10 is covered with the second insulating material 61 in a portion area 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 since the first grid line 10 is covered with the insulating adhesive only in a portion of the area located on the center line of the second pad point 32, the product cost will not be excessively increased. Of course, the second insulating material 61 may be in other embodiments as long as the purpose of insulation is achieved.

[0073] When performing ribbon welding, the insulating effect of the second insulating material 61 prevents the first grid line 10 from coming into contact with the ribbon in a portion of the region located on the center line of the second pad point 32, thereby effectively avoiding the occurrence of a short circuit. Furthermore, the second insulating material 61 is manufactured 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-described Examples 1 to 10, we will now perform model calculations.

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

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

[0077] Battery conversion efficiency is an important performance evaluation indicator for back-contact batteries; higher efficiency indicates better performance, and in the industry, a 0.1% increase is considered a significant improvement. As can be seen from the table, adopting the solution in Figure 3 solves the yield and reliability problems on the module side, but performance deteriorates significantly, with a decrease of 0.789%. Adopting the solution in Figure 4 of the present invention achieves both yield and reliability on the module side while reducing efficiency loss to 0.12%. Adopting the optimized solutions in Figures 5 to 9 of the present invention reduces efficiency loss to 0.003%, and since the test reproducibility of the conversion efficiency of back-contact batteries is currently around ±0.05%, this efficiency loss becomes too low to be monitored and can be ignored. Example 11

[0078] This embodiment 11 provides a back-contact battery including the electrode structure described in Embodiments 1 to 10, wherein the electrode structure is installed on the backlight surface of the back-contact battery.

[0079] In the electrode structure provided in the embodiment of the present invention, the first pad point 31 is positioned away from the first main grid 51, and the connection between the first pad point 31 and the first main grid 51 is achieved by the connecting action of the first connecting electrode 41, and since the first main grid 51 is positioned at the first edge of the back contact battery, the first pad point 31 is far from the first edge of the back contact battery. In the current collection process, the first grid line 10 collects the current in the first polarity region, and the first grid line 10 further transmits the collected current to the first pad point 31, and further transmits it from the first pad point 31 to the first main grid 51 via the first connecting electrode 41, thereby completing the current collection. Compared to the first electrode pattern design of the background art, the electrode structure of the present invention does not require printing insulating adhesive over a large area, so high-temperature paste can be selected for the first pad point 31 and the first main grid 51, reducing costs and ensuring reliability. Furthermore, since the first pad point 31 and the first main grid 51 do not require excessive height, paste consumption is reduced, and because it is not necessary to print insulating adhesive over a large area, the problem of poor adhesion with some pastes is eliminated, and the difficulty of mass production is reduced. Compared to the second electrode pattern design of the background art, since the first main grid 51 is located at the first edge of the back contact battery and the first pad point 31 is far from the first edge of the back contact battery, the problem of stress concentration in the welding process can be avoided, improving module yield and module reliability. Compared to the third electrode pattern design of the background art, since photogenerated electron holes can reach isomer regions without having to travel long distances to achieve current collection, a higher photoelectric conversion efficiency is sufficiently ensured. Example 12

[0080] This embodiment 12 provides a back-contact battery module including the back-contact battery described in embodiment 11.

[0081] In the electrode structure provided in the embodiment of the present invention, the first pad point 31 is positioned away from the first main grid 51, and the connection between the first pad point 31 and the first main grid 51 is achieved by the connecting action of the first connecting electrode 41, and since the first main grid 51 is positioned at the first edge of the back contact battery, the first pad point 31 is far from the first edge of the back contact battery. In the current collection process, the first grid line 10 collects the current in the first polarity region, and the first grid line 10 further transmits the collected current to the first pad point 31, and further transmits it from the first pad point 31 to the first main grid 51 via the first connecting electrode 41, thereby completing the current collection. Compared to the first electrode pattern design of the background art, the electrode structure of the present invention does not require printing insulating adhesive over a large area, so high-temperature paste can be selected for the first pad point 31 and the first main grid 51, reducing costs and ensuring reliability. Furthermore, since the first pad point 31 and the first main grid 51 do not require excessive height, paste consumption is reduced, and because it is not necessary to print insulating adhesive over a large area, the problem of poor adhesion with some pastes is eliminated, and the difficulty of mass production is reduced. Compared to the second electrode pattern design of the background art, since the first main grid 51 is located at the first edge of the back contact battery and the first pad point 31 is far from the first edge of the back contact battery, the problem of stress concentration in the welding process can be avoided, improving module yield and module reliability. Compared to the third electrode pattern design of the background art, since photogenerated electron holes can reach isomer regions without having to travel long distances to achieve current collection, a higher photoelectric conversion efficiency is sufficiently ensured. Example 13

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

[0083] In the electrode structure provided in the embodiment of the present invention, the first pad point 31 is positioned away from the first main grid 51, and the connection between the first pad point 31 and the first main grid 51 is achieved by the connecting action of the first connecting electrode 41, and since the first main grid 51 is positioned at the first edge of the back contact battery, the first pad point 31 is far from the first edge of the back contact battery. In the current collection process, the first grid line 10 collects the current in the first polarity region, and the first grid line 10 further transmits the collected current to the first pad point 31, and further transmits it from the first pad point 31 to the first main grid 51 via the first connecting electrode 41, thereby completing the current collection. Compared to the first electrode pattern design of the background art, the electrode structure of the present invention does not require printing insulating adhesive over a large area, so high-temperature paste can be selected for the first pad point 31 and the first main grid 51, reducing costs and ensuring reliability. Furthermore, since the first pad point 31 and the first main grid 51 do not require excessive height, paste consumption is reduced, and because it is not necessary to print insulating adhesive over a large area, the problem of poor adhesion with some pastes is eliminated, and the difficulty of mass production is reduced. Compared to the second electrode pattern design of the background art, since the first main grid 51 is located at the first edge of the back contact battery and the first pad point 31 is far from the first edge of the back contact battery, the problem of stress concentration in the welding process can be avoided, improving module yield and module reliability. Compared to the third electrode pattern design of the background art, since photogenerated electron holes can reach isomer regions without having to travel long distances to achieve current collection, a higher photoelectric conversion efficiency is sufficiently ensured.

[0084] The foregoing are merely preferred embodiments of the present invention and do not limit the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention are all included within the scope of protection of the present invention.

Claims

1. The first polarity region and, The second polarity region, The first edge and, The first polarity region is collected, and a first grid line extends along the first direction, The second polarity region is collected, and a second grid line extends along the first direction, A first main grid is installed on the side closer to the first edge and connected to the first grid line, Multiple first pad points, It includes a plurality of first connecting electrodes connecting the first main grid and the first pad point, The distance between the first pad point and the first edge is greater than the distance between the first principal grid and the first edge. The second grid line is connected to the first curved grid line located between the first main grid and the first pad point. The first curved grid line is, In the first direction, it is provided so as to overlap with the first pad point, such that a portion of it does not come into contact with both the first pad point and the first main grid. It has an elongated collection section that does not contact either the first pad point or the first main grid, collects the second polar region, and extends along the first direction, A rear-contact battery characterized by the following features.

2. The back-contact battery according to claim 1, characterized in that the first curved grid line passes through at least one of the first grid lines.

3. The back-contact battery according to claim 1, characterized in that the center line of the first connecting electrode and the center line of the first pad point are not on the same straight line.

4. The back-contact battery according to claim 1, further comprising a third grid line connecting the first main grid and the first pad point, wherein the third grid line is installed adjacent to the first connecting electrode, and the width of the third grid line is smaller than the width of the first connecting electrode.

5. The back-contact battery according to claim 1, characterized in that the second grid line is covered with the first insulating material in a portion region located at the center line of the first pad point.

6. The back-contact battery according to claim 1, characterized in that the distance between the first main grid and the first edge is 0.01 mm to 3 mm.

7. The back contact battery according to claim 6, characterized in that the distance between the first pad point and the first edge is from 1 mm to 20 mm.

8. A second main grid is installed on the side of the back contact battery that is closer to the second edge which is opposite to the first edge, and is connected to the second grid line, Multiple second pad points, The system further includes a plurality of second connecting electrodes connecting the second main grid and the second pad point, The back contact battery according to claim 1, characterized in that the distance between the second pad point and the second edge is greater than the distance between the second principal grid and the second edge.

9. The back-contact battery according to claim 8, characterized in that the first grid line includes a second curved grid line located between the second principal grid and the second pad point, the second curved grid line each curves toward the second principal grid and the second pad point and neither contacts the second principal grid and the second pad point, or the second curved grid line curves toward the second principal grid and does not contact the second principal grid, or the second curved grid line curves toward the second pad point and does not contact the second pad point.

10. The back-contact battery according to claim 9, characterized in that the second curved grid line passes through at least one of the second grid lines.

11. The back-contact battery according to claim 9, characterized in that the center line of the second connecting electrode and the center line of the second pad point are on the same straight line.

12. The back-contact battery according to claim 9, further comprising a fourth grid line connecting the second main grid and the second pad point, wherein the fourth grid line is installed adjacent to the second connecting electrode, and the width of the fourth grid line is smaller than the width of the second connecting electrode.

13. The back contact battery according to claim 8, characterized in that the first grid line is covered with the second insulating material in a portion region located at the center line of the second pad point.

14. The back-contact battery according to claim 8, characterized in that the distance between the second main grid and the second edge is 0.01 mm to 3 mm.

15. The back contact battery according to claim 14, characterized in that the distance between the second pad point and the second edge is 1 mm to 20 mm.

16. A rear contact battery module characterized by including a rear contact battery according to any one of claims 1 to 15.

17. A rear contact battery system characterized by including the rear contact battery module described in claim 16.

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