Electrode Structure, Battery, Module, and Battery System of Back Contact Battery

Abstract

SOLUTION: To provide the present invention related to a technical field of a solar battery, specifically, related to an electrode structure of a rear contact battery, a rear contact battery, a rear contact battery module, and a rear contact battery system, in which the electrode structure contains: a first grid line for collecting a first polarity region; a second grid line for collecting a second polarity region; a first main grid that is installed on the side near from a first edge of the rear contact battery, and is connected to the first grid line; a first pad point; and a first connection electrode that connects the first main grid and the first pad point, and a distance of the first pad point and the first edge is larger than the distance of the first main grid and the first edge.EFFECT: An electrode structure can improve reliability, reduce a cost, improve a yield of a product, and secure an 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 located on the front and back surfaces of the cell sheet, respectively. The front surface of the cell is the light-receiving surface. Due to the covering of the metal emitter contact electrode on the front surface, inevitably, a part of the incident sunlight is reflected and shielded by the metal electrode, causing some light loss. The covering area of the front metal electrode of a general crystalline silicon solar cell is about 7%. By reducing the front covering 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 surface (non-light-receiving surface) of the cell. Since there is no shielding by metal electrodes on the light-receiving surface of the cell, the short-circuit current of the cell sheet can be effectively increased. Also, on the back surface, 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 a high conversion efficiency but also looks more beautiful, and the assembly of the all-back electrode module is also easier.

[0004] The electrode pattern design of the 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 FIG. 1, an insulating adhesive 3 is printed on the opposite-sex electrodes to form insulation, while the same-sex electrodes are exposed. Subsequently, the pad points 1 and the bus bar 2 are printed to contact the same-sex electrodes. However, the insulating adhesive 3 cannot withstand high temperatures, and the pad points 1 and the bus bar 2 are formed by post-printing. Therefore, only low-temperature paste can be selected for the pad points 1 and the bus bar 2, which increases the cost and there are reliability issues in the use of low-temperature paste. The insulating adhesive 3 has a height of about 30 μm to form good insulation, and the pad points 1 and the bus bar 2 need to have a height exceeding 30 μm to avoid disconnection, which increases the paste consumption and further increases the cost. In addition, there are problems such as low adhesiveness in the insulating adhesive 3 and some pastes, and mass production has significant challenges.

[0006] 2. Referring to FIG. 2, the fine grid 4 is cut by the opposite-sex pad points 5 and the bus bar 6, and the pad points 5 and the bus bar 6 at the edge are located at the bevel edge of the silicon wafer. The pad points 5 and the bus bar 6 are at the edge of the silicon wafer. In the module manufacturing process, the ribbon also needs to cover the edge of the silicon wafer. There are a large number of microcracks at the edge of the silicon wafer, which may cause the problem of silicon wafer breakage due to stress concentration in the ribbon welding process, resulting in a decrease in the module yield and a decrease in the reliability of the module.

[0007] 3. Referring to FIG. 3, the fine grid 7 is cut by the opposite-sex pad points 8 and the bus bar 9. The outer pad points 8 and the bus bar 9 are at a certain distance from the bevel edge of the silicon wafer, and the peripheries of the outer pad points 8 and the bus bar 9 are set to the same polarity. The third design solves the problems existing in the above-mentioned first design and second design. However, the photo-generated electron-hole pairs need to diffuse into the opposite-sex region to form efficient collection. In the third design, the outer photo-generated electron-hole pairs need to span a distance on the order of mm and thus cm to reach the opposite-sex region. Due to the recombination loss during the long-distance diffusion, the short-circuit current decreases, and the series resistance increases, causing a loss of the fill factor and further resulting in very low photovoltaic conversion performance.

[0008] Therefore, in order to solve the above problems, designing the electrode structure of the back-contact cell, the back-contact cell, the back-contact cell module, and the back-contact cell system is always one of the problems that should be studied as an important issue by those skilled in the art.

SUMMARY OF THE INVENTION

[0009] The present invention provides an electrode structure of a back-contact cell so as to solve the technical problems that the cost of the conventional back-contact solar cell is high, the reliability is low, and the photovoltaic conversion performance is low.

[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 installed on a side close to the first edge of the back-contact cell and connected to the first grid line, A first pad point, A first connection electrode connecting the first main grid and the first pad point respectively, and includes, 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, and provides an electrode structure of a back-contact cell.

[0012] Furthermore, the second grid line includes a first curved grid line located between the first main grid and the first pad point. The first curved grid lines are curved towards the first main grid and the first pad point respectively, and neither of them is in contact with the first main grid and the first pad point, or the first curved grid line is curved towards the first main grid and not in contact with the first main grid, or the first curved grid line is curved towards the first pad point and not in contact with 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 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 is installed adjacent to the first connection electrode, and the width of the third grid line is smaller than the width of the first connection electrode.

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

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

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

[0019] Furthermore, the electrode structure includes a second main grid installed on a side close to a second edge opposite to the first edge of the back contact battery and connected to the second grid line, a 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 main grid and the second edge.

[0020] Furthermore, the first grid line includes a second curved grid line located between the second main grid and the second pad point. The second curved grid lines are curved 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 line is curved towards the second main grid and not in contact with the second main grid, or the second curved grid line is curved towards the second pad point and not in contact with the second pad point.

[0021] Furthermore, the second curved grid line passes 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 is installed adjacent to the second connection electrode, and the width of the fourth grid line 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 described above, and the electrode structure further provides a back contact battery 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 photo-generated electron holes do not need to span a long distance to reach the opposite-sex 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

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Mode for Carrying Out the Invention

[0032] In order to make the object, technical solution and advantages of the present invention more clear, hereinafter, the present invention will be described in more detail in association with the drawings and embodiments. It should be understood that the specific examples described here are only for interpreting the present invention and not for limiting 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 connection electrode connecting the first main grid and the first pad point respectively. The first grid line is for collecting the current in the first polarity region. By merging into the first main grid through the first pad point and the first connection electrode, the collection of the current is realized. The electrode structure does not need to print an insulating adhesive over a large area. The first pad point is not installed at the first edge of the back contact battery together with the first main grid. The photo-generated electron-hole pairs do not need to span a long distance to reach the opposite polarity region. Thereby, the electrode structure can improve the reliability, reduce the cost, improve the product yield, and ensure a very excellent photoelectric conversion efficiency. Example 1

[0034] Referring to FIG. 4, this Example 1 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 installed on the side close to the first edge of the back contact battery and connected to the first grid line 10, a first pad point 31, and a first connection electrode 41 connecting the first main grid 51 and the first pad point 31 respectively, provides an electrode structure of a back contact battery, where 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 an embodiment of the present invention, the first grid line 10 is used to collect the current in the first polarity region, the second grid line 20 is used to collect the current in the second polarity region, and 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, when 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 when 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 FIGS. 4 to 10, for the convenience of discrimination, the first grid lines 10 in the blackened portions have the same polarity, the second grid lines 20 in the non-blackened portions have the same polarity, and the polarities of the first grid lines 10 and the second grid lines 20 are opposite. The first pad points 31, the first connection electrodes 41, and the first main grids 51 in the blackened portions have the same polarity as the first grid lines 10.

[0037] The first grid lines 10 and the second grid lines 20 are alternately installed, and both the first grid lines 10 and the second grid lines 20 are horizontal with respect 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 installed in the vertical direction, and both the first grid lines 10 and the second grid lines 20 are horizontal with respect to the upper edge line and the lower edge line of the back contact battery. The back contact battery is substantially rectangular, and the substantially rectangular back contact battery may be, for example, square, or another rectangle, and may have standard corners, cut-off corners, or rounded corners, which are set according to actual manufacturing requirements and are not specifically limited here. Also, 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 widths and distances 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-coated copper grid line. In an embodiment of the present invention, it is understandable that the first grid line 10 and the second grid line 20 may select grid lines of the same or different metal types. For example, both the first grid line 10 and the second grid line 20 may select aluminum grid lines, or the first grid line 10 may select an aluminum grid line and the second grid line 20 may select a silver grid line. When 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 the silver grid line is printed on the doped region of the back contact battery by screen printing. When the first grid line 10 or the second grid line 20 is a copper grid line, it is plated on the doped region 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 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 main grid 51 and the first edge is from 0.01 mm to 3 mm, where it refers to the distance between the edge of the first main grid 51 close to the first edge and the first edge. For example, the distance between the first main grid 51 and the first edge is 0.05 mm, 1 mm, 2 mm, 3 mm, or other parameter values from 0.01 mm to 3 mm. The distance between the first pad point 31 and the first edge is from 1 mm to 20 mm, where it refers to the distance between the edge of the first pad point 31 close to the first edge 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 from 1 mm to 20 mm, but 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.

[0041] In an embodiment of the present invention, the first pad point 31 is installed away from the first main grid 51. The connection between the first pad point 31 and the first main grid 51 is realized by the connection action of the first connection electrode 41. Since the first main grid 51 is installed at the first edge of the back contact battery, the first pad point 31 is far away 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. The first grid line 10 further transmits the collected current to the first pad point 31, and then transmits it from the first pad point 31 to the first main grid 51 through the first connection electrode 41 to complete the current collection. Compared with the first electrode pattern design in the background art, the electrode structure of the present invention does not require printing of an insulating adhesive over a large area. Therefore, the first pad point 31 and the first main grid 51 can select a high-temperature paste, which reduces the cost and ensures reliability. Also, since the first pad point 31 and the first main grid 51 do not require excessive height, the consumption of the paste is reduced. And since there is no need to print an insulating adhesive over a large area, there is no problem of low adhesion to some pastes, and the difficulty of mass production is reduced. Compared with the second electrode pattern design in 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 away from the first edge of the back contact battery, the problem of stress concentration in the welding process can be avoided, the yield of the module is improved, and the reliability of the module is improved. Compared with the third electrode pattern design in the background art, since the photo-generated electron holes can reach the different polarity region without spanning a long distance to realize current collection, a higher photoelectric conversion efficiency is fully ensured. Example 2

[0042] Based on Example 1, the second grid line 20 described in this Example 2 includes a first curved grid line located between the first main grid 51 and the first pad point 31. The first curved grid lines are curved towards the first main grid 51 and the first pad point 31 respectively, and neither of them is in contact with the first main grid 51 and the first pad point 31, or the first curved grid line is curved towards the first main grid 51 and not in contact with the first main grid 51, or the first curved grid line is curved towards the first pad point 31 and not in contact with the first pad point 31.

[0043] Referring to FIG. 5, the first curved grid line is defined as a first sub-curved grid line 21. The first grid line 10 includes a first pad point connection grid line 11 connected to the first pad point 31 and a first main grid connection grid line 12 connected to the first main grid 51. The first pad point connection grid line 11 and the first main grid connection grid line 12 are installed adjacent to each other, and a gap is formed between them. The first sub-curved grid line 21 passes through the gap, curves towards the first main grid 51 and the first pad point 31 respectively, and neither of them 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 connection grid line 11 and / or the first main grid connection grid line 12 may be omitted. However, by installing the first pad point connection grid line 11 and / or the first main grid connection grid line 12, the grid lines can be arranged more uniformly, and it is possible to avoid the situation where current collection cannot be achieved in some small areas.

[0044] Referring to FIG. 6, the first curved grid line is defined as the second sub-curved grid line 24. The first grid line 10 includes a second main grid connection grid line 14 connected to the first main grid 51. A gap is formed between the second main grid connection grid line 14 and the first pad point 31. The second sub-curved grid line 24 passes through the gap and curves towards the first main grid 51 without contacting the first main grid 51. In other embodiments, in order to achieve a more uniform arrangement of the grid lines and avoid the inability to collect current in some small regions, pad point connection grid lines may be additionally installed.

[0045] Referring to FIG. 7, the first curved grid line is defined as the third sub-curved grid line 27. The first grid line 10 includes a second pad point connection grid line 16 connected to the first pad point 31. A gap is formed between the second pad point connection grid line 16 and the first main grid 51. The third sub-curved grid line 27 passes through the gap and curves towards the first pad point 31 without contacting the first pad point 31. In other embodiments, in order to achieve a more uniform arrangement of the grid lines and avoid the inability to collect current in some small regions, main grid connection grid lines may be additionally installed.

[0046] In an embodiment of the present invention, the length of the first curved grid line can be determined according to the size of the deployable area. The first curved grid line is formed to extend divergently, and it is possible to further enhance the current collection ability by fully utilizing the current collectable area.

[0047] Furthermore, based on the above embodiments, the first curved grid line passes through at least one of the first grid lines 10. A plurality of first grid lines 10 may be arranged in the area or the vicinity area between the first pad point 31 and the first main grid 51. When a plurality of 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 more divergently, thereby further enhancing the current collection ability. Example 3

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

[0049] In an embodiment of the present invention, the center line of the first pad point 31 is 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, when the first pad point 31 is of positive polarity, the second grid line 20 is of negative polarity. Therefore, by installing the center line of the first connection electrode 41 offset from the center line of the first pad point 31, that is, by installing the center line of the first connection electrode 41 offset from the installation line of the second grid line 20, it is possible to install the center line of the first connection electrode 41 on the installation line of the first grid line 10. The first connection electrode 41 and the first grid line 10 have the same polarity, thereby achieving the purpose that the grid lines of the opposite polarity in the region adjacent to the first pad point 31 are more uniformly distributed and further enhancing the current collection ability. Example 4

[0050] Referring to FIG. 9 and based on Example 2, the electrode structure described in this Example 4 further includes a third grid line 18 that connects 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, usually, the first connection electrode 41 does not contact the substrate of the back contact battery. In this case, the photo-generated electron holes in the region where the first connection electrode 41 is located cannot be efficiently collected. Therefore, a third grid line 18 is installed in the region adjacent to the first connection electrode 41, and the third grid line 18 can contact the substrate, thereby further enhancing the current collection ability. Example 5

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

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

[0054] When performing ribbon welding, due to the insulating effect of the first insulating material 62, it is possible to prevent the second grid line 20 from contacting the ribbon in the partial area located on the center line of the first pad point 31, thereby effectively avoiding the occurrence of a short circuit. And 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 the electrode materials of 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 this Example 6 is a second main grid 52 installed on the side close to the second edge facing the first edge of the back contact battery and connected to the second grid line 20, a second pad point 32, and a second connection electrode 42 connecting the second main grid 52 and the second pad point 32 respectively, and further includes 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 FIG. 4, the first edge refers to the leftmost side of the back contact battery, and the second edge refers to the rightmost side of the back contact battery. Between the first pad point 31 and the second pad point 32, a plurality of pad points are similarly provided, and the pad points in this part may be installed 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 FIG. 4, the distance between the leftmost side of the second pad point 32 and the leftmost edge of the back contact cell is greater than the distance between the leftmost side of the second main grid 52 and the leftmost edge of the back contact cell.

[0058] In this embodiment, the distance between the second main grid 52 and the second edge is from 0.01 mm to 3 mm, where this refers to the distance between the edge of the second main grid 52 close to the second edge and the second edge. For example, the distance between the second main grid 52 and the second edge is 0.05 mm, 1 mm, 2 mm, 3 mm, or other parameter values from 0.01 mm to 3 mm. The distance between the second pad point 32 and the second edge is from 1 mm to 20 mm, where this refers to the distance between the edge of the second pad point 32 close 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 other parameter values from 1 mm to 20 mm, but 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.

[0059] In an embodiment of the present invention, the second pad point 32 is installed away from the second main grid 52. The connection between the second pad point 32 and the second main grid 52 is realized by the connection action of the second connection electrode 42. Since the second main grid 52 is installed at the second edge of the back contact battery, the second pad point 32 is far away 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. 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 through the second connection electrode 42 to complete the current collection. At both edges of the back contact battery, there are respectively installed pad points, main grids, and connection electrodes connecting the pad points and the main grids. Compared with the first electrode pattern design in the background art, since there is no need to print the insulating adhesive over a large area, the pad points and the main grids can select high-temperature paste, which reduces the cost and ensures reliability. Also, since the pad points and the main grids do not require excessive height, the consumption of the paste is reduced. And since there is no need to print the insulating adhesive over a large area, there is no problem of low adhesiveness with some pastes, and the difficulty of mass production is reduced. Compared with the second electrode pattern design in the background art, since the main grid is located at the edge of the back contact battery and the pad point is far away from the edge of the back contact battery, the problem of stress concentration in the welding process can be avoided, the yield of the module is improved, and the reliability of the module is improved. Compared with the third electrode pattern design in the background art, since the photo-generated electron holes can reach the different region without spanning a long distance to realize current collection, a higher photoelectric conversion efficiency is fully ensured. Example 7

[0060] Based on Example 6, the first grid line 10 described in this Example 7 includes a second curved grid line located between the second main grid 52 and the second pad point 32. The second curved grid lines are curved towards the second main grid 52 and the second pad point 32 respectively, and neither of them is in contact with the second main grid 52 and the second pad point 32, or the second curved grid line is curved towards the second main grid 52 and not in contact with the second main grid 52, or the second curved grid line is curved towards the second pad point 32 and not in contact with the second pad point 32.

[0061] Referring to FIG. 5, the second curved grid line is defined as the fourth sub-curved grid line 13. The second grid line 20 includes a third pad point connection grid line 22 connected to the second pad point 32 and a third main grid connection grid line 23 connected to the second main grid 52. The third pad point connection grid line 22 and the third main grid connection grid line 23 are installed adjacent to each other, and a gap is formed between them. The fourth sub-curved grid line 13 passes through the gap, curves towards the second main grid 52 and the second pad point 32 respectively, and neither of them 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 connection grid line 22 and / or the third main grid connection grid line 23 may be omitted. However, by installing the third pad point connection grid line 22 and / or the third main grid connection grid line 23, the grid lines can be arranged more uniformly, and it is possible to avoid the situation where current collection cannot be achieved in some small regions.

[0062] Referring to FIG. 6, the second curved grid line is defined as the fifth sub-curved grid line 15, and the second grid line 20 includes a fourth pad point connection grid line 25 connected to the second pad point 32 and a fourth main grid connection grid line 26 connected to the second main grid 52. The fourth pad point connection grid line 25 and the fourth main grid connection grid line 26 are adjacently installed, and a gap is formed therebetween. 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 installation of the fourth pad point connection grid line 25 and / or the fourth main grid connection grid line 26 may be omitted. However, by installing the fourth pad point connection grid line 25 and / or the fourth main grid connection grid line 26, the grid lines can be arranged more uniformly, and it is possible to avoid the situation where current collection cannot be achieved in some small regions.

[0063] Referring to FIG. 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 connection grid line 28 connected to the second pad point 32. A gap is formed between the fifth pad point connection grid line 28 and the second main grid 52. 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, in order to achieve a more uniform arrangement of the grid lines and avoid the situation where current collection cannot be achieved in some small regions, a main grid connection grid line may be additionally installed.

[0064] In the embodiments of the present invention, the length of the second curved grid line can be determined according to the size of the deployable area. The second curved grid line is formed to extend divergently, and it is possible to further improve the current collection ability by fully utilizing the current collectable area.

[0065] Furthermore, based on the above embodiment, the second curved grid line passes through at least one of the second grid lines 20. A plurality of second grid lines 20 may be arranged in the region or the vicinity region between the second pad point 32 and the second main grid 52. When a plurality of gaps are formed by the arrangement of the second grid lines 20, the second curved grid line can pass through the gaps in order, and each time it passes through a gap, it is further formed to extend divergently, thereby further enhancing the current collection ability.

[0066] When combined with Example 2, at the edges at both ends of the back contact battery, the installation methods of the first curved grid line and the second curved grid line may be different, 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 FIG. 8, at the first edge of the back contact battery, the first curved grid line is not installed, but at the second edge of the back contact battery, the second curved grid line is installed, and the second curved grid lines are curved toward the second main grid 52 and the second pad point 32 respectively. Example 8

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

[0068] In the embodiments of the present invention, the center line of the second pad point 32 is 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, when the second pad point 32 is of negative polarity, the second grid line 20 is of negative polarity. Therefore, by installing the center line of the second connection electrode 42 and the center line of the second pad point 32 on the same straight line, it is possible to realize that the center line of the second connection electrode 42 is installed on the installation line of the second grid line 20, and the second connection electrode 42 and the second grid line 20 have the same polarity, thereby achieving the purpose that the grid lines of the opposite polarity in the region adjacent to the second pad point 32 are more uniformly distributed and further enhancing the current collection ability. Example 9

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

[0070] In the embodiments of the present invention, usually, the second connection electrode 42 does not contact the substrate of the back contact battery. In this case, since the photo-generated electron holes in the region where the second connection electrode 42 is located cannot be efficiently collected, a fourth grid line 29 is installed in the region adjacent to the second connection electrode 42. The fourth grid line 29 can contact the substrate, thereby further enhancing the current collection ability. Example 10

[0071] Based on Example 6, in the first grid line 10 described in this Example 10, a partial region located on the center line of the second pad point 32 is covered with a second insulating material 61.

[0072] The second insulating material 61 may adopt a form of being covered with an insulating adhesive. Since the first grid line 10 is only covered with the insulating adhesive in the partial region located on the center line of the second pad point 32, the product cost will not be excessively increased. Of course, if the purpose of insulation can be achieved, the second insulating material 61 may adopt other embodiments.

[0073] When performing ribbon welding, due to the insulating effect of the second insulating material 61, it is possible to prevent the first grid line 10 from contacting the ribbon in the partial region located on the center line of the second pad point 32, thereby effectively avoiding the occurrence of a short circuit. And 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 the electrode materials of the second pad point 32 and the second main grid 52.

[0074] Based on the above-described Examples 1 to 10, modeling calculations are performed here.

[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] The conversion efficiency of the battery is an important performance evaluation index of the back contact battery. The higher it is, the better the performance. In the industry, every 0.1% increase is recognized as a leap-forward progress. As can be seen from the table, if the solution of FIG. 3 is adopted, the yield and reliability problems on the module side are solved, but the performance is significantly reduced, and the reduction value reaches 0.789%. If the solution of FIG. 4 of the present invention is adopted, the yield and reliability on the module side are made compatible, and the efficiency loss is reduced to 0.12%. If the optimal solution of FIGS. 5 to 9 of the present invention is adopted, the efficiency loss can be reduced to 0.003%. Currently, the test reproducibility of the conversion efficiency of the back contact battery is ~±0.05%. Therefore, this efficiency loss is so low that it cannot be monitored and can be ignored. Example 11

[0078] This Example 11 provides a back contact battery including the electrode structures described in Examples 1 to 10, and the electrode structure is installed on the backlight surface of the back contact battery.

[0079] In the electrode structure provided by the embodiment of the present invention, the first pad point 31 is installed away from the first main grid 51. The connection between the first pad point 31 and the first main grid 51 is realized by the connection action of the first connection electrode 41. Since the first main grid 51 is installed on the first edge of the back contact battery, the first pad point 31 is far away 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. The first grid line 10 further transmits the collected current to the first pad point 31, and then transmits it from the first pad point 31 to the first main grid 51 through the first connection electrode 41 to complete the current collection. Compared with the first electrode pattern design in the background technology, the electrode structure of the present invention does not need to print the insulating adhesive over a large area. Therefore, the first pad point 31 and the first main grid 51 can select high-temperature paste, which reduces the cost and ensures the reliability. Also, since the first pad point 31 and the first main grid 51 do not require excessive height, the consumption of the paste is reduced. And since there is no need to print the insulating adhesive over a large area, there is no problem of low adhesion with some pastes, and the difficulty of mass production is reduced. Compared with the second electrode pattern design in the background technology, since the first main grid 51 is located on the first edge of the back contact battery and the first pad point 31 is far away from the first edge of the back contact battery, the problem of stress concentration in the welding process can be avoided, the yield of the module is improved, and the reliability of the module is improved. Compared with the third electrode pattern design in the background technology, since the photo-generated electron-hole pairs can reach the different polarity regions without spanning a long distance to realize current collection, a higher photoelectric conversion efficiency is fully ensured. Example 12

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

[0081] In the electrode structure provided by the embodiment of the present invention, the first pad point 31 is installed away from the first main grid 51. The connection between the first pad point 31 and the first main grid 51 is realized by the connection action of the first connection electrode 41. Since the first main grid 51 is installed at the first edge of the back contact battery, the first pad point 31 is far away 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 then from the first pad point 31 through the first connection electrode 41 to the first main grid 51 to complete the current collection. Compared with the first electrode pattern design in the background technology, the electrode structure of the present invention does not need to print the insulating adhesive over a large area. Therefore, the first pad point 31 and the first main grid 51 can select high-temperature paste, which reduces the cost and ensures the reliability. Also, since the first pad point 31 and the first main grid 51 do not require excessive height, the consumption of the paste is reduced, and since there is no need to print the insulating adhesive over a large area, there is no problem of low adhesion to some pastes, and the difficulty of mass production is reduced. Compared with the second electrode pattern design in the background technology, 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 away from the first edge of the back contact battery, the problem of stress concentration in the welding process can be avoided, the yield of the module is improved, and the reliability of the module is improved. Compared with the third electrode pattern design in the background technology, since the photo-generated electron-hole pairs can reach the different polarity regions without spanning a long distance to realize current collection, a higher photoelectric conversion efficiency is fully ensured. 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 by the embodiment of the present invention, the first pad point 31 is installed away from the first main grid 51. The connection between the first pad point 31 and the first main grid 51 is realized by the connection action of the first connection electrode 41. Since the first main grid 51 is installed at the first edge of the back contact battery, the first pad point 31 is far away 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. The first grid line 10 further transmits the collected current to the first pad point 31, and then transmits it from the first pad point 31 to the first main grid 51 through the first connection electrode 41 to complete the current collection. Compared with the first electrode pattern design in the background technology, the electrode structure of the present invention does not need to print the insulating adhesive over a large area. Therefore, the first pad point 31 and the first main grid 51 can select high-temperature paste, which reduces the cost and ensures the reliability. Also, since the first pad point 31 and the first main grid 51 do not require excessive height, the consumption of the paste is reduced. And since there is no need to print the insulating adhesive over a large area, there is no problem of low adhesiveness with some pastes, and the difficulty of mass production is reduced. Compared with the second electrode pattern design in the background technology, 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 away from the first edge of the back contact battery, the problem of stress concentration in the welding process can be avoided, the yield of the module is improved, and the reliability of the module is improved. Compared with the third electrode pattern design in the background technology, the photo-generated electron-hole pairs can reach the different polarity regions without spanning a long distance to realize current collection. Therefore, a higher photoelectric conversion efficiency is fully ensured.

[0084] The above are only the preferred embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions, 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 grid line that collects first polarity regions and extends along a first direction; a second grid line that collects second polarity regions and extends along the first direction; a first main grid installed on a side close to a first edge of the back contact battery and connected to the first grid line; a second main grid installed on a side close to a second edge opposite to the first edge of the back contact battery and connected to the second grid line; a first pad point that does not contact the second grid line; a second pad point that does not contact the first grid line; a first connection electrode that connects the first main grid and the first pad point respectively; a second connection electrode that connects the second main grid and the second pad point respectively, and includes 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; 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; a first curved grid line located between the first main grid and the first pad point is connected to the second grid line; the first grid line does not contact the first main grid, the first pad point, another first grid line, and the first connection electrode, and includes an extending portion extending along the first direction; the extending portion is connected to another first grid line through a connection grid line whose extension line extending along the first direction penetrates the first pad point, is located between the second main grid and the second pad point, and passes through a first gap of the second grid line; An electrode structure of a back contact battery, characterized in that.

2. the first grid line includes a first pad point connection grid line connecting to the first pad point and a first main grid connection grid line connecting to the first main grid; a second gap is formed between the first pad point connection grid line and the first main grid connection grid line; the first curved grid line passes through the second gap; An electrode structure of a back contact battery according to claim 1, characterized in that.

3. An electrode structure of a back contact battery according to claim 2, characterized in that the first curved grid line passes through the second gap. **Claim 4**: The first pad point is rectangular, a center line of the first pad point extends along a second direction orthogonal to the first direction, and a center line of the first connection electrode and the center line of the first pad point are not on the same straight line. The electrode structure of the back contact battery according to claim 2. **Claim 5** The electrode structure of the back contact battery according to claim 2, further comprising a third grid line connecting the first main grid and the first pad point respectively, the third grid line being installed adjacent to the first connection electrode, and a width of the third grid line being smaller than a width of the first connection electrode. **Claim 6**: The first pad point is rectangular, a center line of the first pad point extends along a second direction orthogonal to the first direction, and the second grid line is covered with a first insulating material in a partial region located on the center line of the first pad point. The electrode structure of the back contact battery according to claim 1. **Claim 7** The electrode structure of the back contact battery according to claim 1, wherein a distance between the first main grid and the first edge is from 0.01 mm to 3 mm. **Claim 8** The electrode structure of the back contact battery according to claim 7, wherein a distance between the first pad point and the first edge is from 1 mm to 20 mm. **Claim 9** The first grid line includes a second curved grid line located between the second main grid and the second pad point, the second curved grid line curves 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 line curves towards the second main grid and is not in contact with the second main grid, or the second curved grid line curves towards the second pad point and is not in contact with the second pad point. The electrode structure of the back contact battery according to claim 1. **Claim 10** The electrode structure of the back contact battery according to claim 9, wherein the second curved grid line includes the connection grid line. **Claim 11**: The second pad point is rectangular, a center line of the second pad point extends along a second direction orthogonal to the first direction, and a center line of the second connection electrode and the center line of the second pad point are not on the same straight line. The electrode structure of the back contact battery according to claim 9. **Claim 12** Further comprising a fourth grid line connecting the second main grid and the second pad point respectively, the fourth grid line is installed adjacent to the second connection electrode, and the width of the fourth grid line is smaller than the width of the second connection electrode. The electrode structure of the back contact battery according to claim 9.

13. The second pad point is rectangular, the center line of the second pad point extends along a second direction orthogonal to the first direction, and the first grid line is covered with a second insulating material in a partial region located on the center line of the second pad point. The electrode structure of the back contact battery according to claim 1.

14. The distance between the second main grid and the second edge is from 0.01 mm to 3 mm. The electrode structure of the back contact battery according to claim 1.

15. The distance between the second pad point and the second edge is from 1 mm to 20 mm. The electrode structure of the back contact battery according to claim 14.

16. A back contact battery comprising the electrode structure according to any one of claims 1 to 15, wherein the electrode structure is installed on the backlight surface of the back contact battery.

17. A back contact battery module comprising the back contact battery according to claim 16.

18. A back contact battery system comprising the back contact battery module according to claim 17.

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