Back contact battery piece and back contact battery assembly

Abstract

The embodiment of the invention relates to the field of photovoltaic technology. The embodiment of the invention provides a back contact battery piece and a back contact battery assembly, the back contact battery piece comprises a body part and grid lines arranged on the body part, the grid lines comprise connecting lines and auxiliary grids, the connecting lines are arranged in the width direction, the auxiliary grids are arranged in the length direction, and the auxiliary grids are electrically connected with the connecting lines. The connecting lines comprise two first connecting lines, and the connecting line located between the first connecting lines is a second connecting line. The second connecting lines are provided with first connecting sections located between the connecting parts, and the first connecting lines are electrically connected with the second connecting lines with the same polarity through the second connecting sections. The width of the first connecting line is larger than that of the first connecting section, and the width of the second connecting section is larger than that of the first connecting section. Through the design, the loss of the current in the transmission process can be reduced, so that the efficiency of the back contact battery piece is improved.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic modules, and in particular to a back-contact cell sheet and a back-contact cell module. Background Art

[0002] With the development of technology, photovoltaic modules have become a commonly used device because of their advantages such as clean, environmentally friendly, renewable, high safety and long service life. The cells in photovoltaic modules can generate photocurrent by absorbing light, which can power other devices. Usually, the edge of the cell has a weaker ability to collect current. During the EL test, the edge of the cell is prone to graying, that is, the CTM performance of the cell is poor, which affects the efficiency of the cell. Summary of the invention

[0003] The embodiments of the present application provide a back-contact battery cell and a back-contact battery assembly for improving the efficiency of the back-contact battery cell.

[0004] The embodiment of the present application provides a back-contact cell, the back-contact cell comprising: Body part; A gate line, wherein the gate line is arranged on the main body; Wherein, the grid line includes a plurality of connection lines and a plurality of auxiliary grids, and the connection lines are arranged in sequence along the width direction of the back contact battery sheet, and the auxiliary grids are arranged in sequence along the length direction of the back contact battery sheet. The connection lines are electrically connected to the auxiliary grids. Among the connection lines, two of the connection lines are first connection lines, and the remaining connection lines are second connection lines. Along the width direction of the back contact battery sheet, the first connection lines are located on opposite sides of the back contact battery sheet, and the second connection lines are located between the first connection lines. The back contact battery sheet also includes a connection portion, and the second connection line is connected to the connection portion. The second connection line includes a first connection segment, and at least a portion of the first connection segment is located between adjacent connection portions. Each of the second connection lines is a first polarity connection line and a second polarity connection line, and the first polarity connection line and the second polarity connection line are arranged alternately with each other. The polarity of the first connection line is the same as that of the first polarity connection line. The back contact battery sheet includes a second connection segment, and the first connection line is electrically connected to the nearest first polarity connection line through the second connection segment. The width of the first connecting segment is a, the width of the first connecting line is b, the width of the second connecting segment is c, and b>a, c>a.

[0005] In a possible implementation manner, the width of the first connecting line is 50 micrometers to 150 micrometers.

[0006] In a possible implementation manner, a distance between the first connecting line and an adjacent second connecting line is 300 micrometers to 400 micrometers.

[0007] In a possible implementation, along the length direction of the back contact cell, the spacing between the auxiliary grids on two opposite sides of the second connecting section is d, and the width c of the second connecting section satisfies: d-380 microns ≤ c ≤ d-300 microns.

[0008] In a possible implementation manner, a width of the second connecting segment is 100 micrometers to 200 micrometers.

[0009] In a possible implementation manner, a width b of the first connecting line and a width c of the second connecting section satisfy: c>b.

[0010] In a possible implementation manner, the auxiliary gate includes a first auxiliary gate and a second auxiliary gate, the first auxiliary gate is electrically connected to the first connecting line, and the second auxiliary gate is electrically connected to the second connecting line; The width of the first auxiliary grid is e, the width of the second auxiliary grid is f, and e>f.

[0011] In a possible implementation manner, the width of the first sub-gate is 10 micrometers to 30 micrometers.

[0012] In a possible implementation manner, the width of the first connecting segment is 14 micrometers to 16 micrometers, and the width of the second auxiliary gate is 8 micrometers to 16 micrometers.

[0013] An embodiment of the present application also provides a back-contact battery assembly, which includes at least one back-contact battery sheet as described in any one of the above.

[0014] The embodiments of the present application provide a back-contact battery cell and a back-contact battery assembly, wherein the back-contact battery cell includes a main body and a grid line arranged on the main body, the grid line includes a connecting line and a sub-grid, the connecting line is arranged along the width direction, the sub-grid is arranged along the length direction, and the sub-grid and the connecting line are electrically connected. The connecting line includes two first connecting lines, and the connecting line located between the first connecting lines is a second connecting line. The second connecting line has a first connecting section located between the connecting parts, and the first connecting line is electrically connected to the second connecting line with the same polarity through the second connecting section. The width of the first connecting line is greater than the width of the first connecting section, and the width of the second connecting section is greater than the width of the first connecting section. Such a design can reduce the loss of current during the transmission process, which is beneficial to improving the efficiency of the back-contact battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0016] Figure 1 A schematic diagram of a back contact cell provided in an embodiment of the present application; Figure 2 A partial schematic diagram of a back-contact cell provided in an embodiment of the present application.

[0017] Reference numerals 1-Body part; 2-grid line; 21-Connecting wire; 211-first connecting line; 212-second connecting line; 212a-first connecting section; 212b-first polarity connection line; 212c-second polarity connection line; 212d-third connecting section; 22-auxiliary grid; 221-first secondary grid; 222-second secondary grid; 3-Connection part; 4- Second connecting section. DETAILED DESCRIPTION

[0018] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0019] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0020] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0021] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0022] like Figure 1 and Figure 2 As shown, an embodiment of the present application provides a back-contact cell, which includes a main body 1 and a gate line 2, and the gate line 2 is arranged on the main body 1. The main body 1 serves as the substrate of the back-contact cell, and is usually a processed silicon wafer. The main body 1 can absorb light and generate photocurrent, and the gate line 2 is used to collect the current generated by the main body 1 and lead the current out. The gate line 2 includes a plurality of connecting wires 21 and a plurality of sub-grids 22, and the connecting wires 21 are arranged in sequence along the width direction X of the back-contact cell. The sub-grids 22 are arranged in sequence along the length direction Y of the back-contact cell. The connecting wires 21 extend along the length direction Y of the back-contact cell, and the sub-grids 22 extend along the width direction X of the back-contact battery. The connecting wires 21 and the sub-grids 22 can be distributed in a grid shape on the surface of the main body 1. Among the multiple connection lines 21, two are first connection lines 211, and the rest are second connection lines 212. Along the width direction X of the back contact battery sheet, the first connection lines 211 are located on opposite sides of the back contact battery sheet, and the second connection lines 212 are located between the first connection lines 211. That is, the first connection lines 211 are located on both sides of the body part 1 near the edge, and the second connection lines 212 are located between the two first connection lines 211. The first connection line 211 and the second connection line 212 are located on the same side of the body part 1. The back contact battery sheet also includes a connection part 3, which is used to electrically connect to the welding strip. The second connection line 212 is connected to the connection part 3. The second connection line 212 includes a first connection section 212a, and at least part of the first connection section 212a is located between adjacent connection parts 3. The second connection line 212 can be divided into a first polarity connection line 212b and a second polarity connection line 212c according to polarity, and the first polarity connection line 212b and the second polarity connection line 212c are spaced apart from each other. That is, the second connection line 212 adjacent to the first polarity connection line 212b is the second polarity connection line 212c, and the second connection line 212 adjacent to the second polarity connection line 212c is the first polarity connection line 212b. The polarity of the first connection line 211 is the same as the polarity of the first polarity connection line 212b. The back contact cell also includes a second connection segment 4, and the first connection line 211 is electrically connected to the nearest first polarity connection line 212b through the second connection segment 4. The width of the first connection segment 212a is a, the width of the first connection line 211 is b, and the width of the second connection segment 4 is c, and b>a, c>a.

[0023] In the solution provided in the embodiment of the present application, the first connection line 211 and the second connection segment 4 are designed to be thickened so that the width of the first connection line 211 and the second connection segment 4 are both greater than the width of the first connection segment 212a. The cross-sectional area of ​​the first connection line 211 and the second connection segment 4 is increased by the thickening design, so that the resistance of the first connection line 211 and the second connection segment 4 can be reduced, thereby reducing the current loss, and improving the uniformity of EL imaging during EL testing, thereby improving the CTM performance of the back contact cell. Since the current loss of the first connection line 211 and the second connection segment 4 is reduced, the current collection capacity of the back contact cell for the edge position can be improved, which is beneficial to improving the overall efficiency of the back contact cell and is more in line with actual usage requirements.

[0024] The first connection line 211 is located at the edge of the main body 1. When the connection part 3 is set on the first connection line 211 to connect with the welding strip, it is difficult to set the welding strip because the first connection line 211 is located at the edge of the main body 1. Moreover, since the welding strip is located at the edge of the back contact battery cell, it is easy to be damaged, which affects the normal use of the back contact battery cell. Therefore, by setting the second connection section 4, the current of the first connection line 211 can be transferred to the second connection line 212 of the same polarity, and the current is drawn out through the connection part 3 set on the second connection line 212. The first connection line 211 does not need to be directly electrically connected to the welding strip, thereby saving costs and reducing the possibility of damage to the welding strip.

[0025] In a possible implementation, the width of the first connection line 211 is 50 micrometers to 150 micrometers. The width of the first connection line 211 can be 50 micrometers, 60 micrometers, 70 micrometers, 80 micrometers, 90 micrometers, 100 micrometers, 110 micrometers, 120 micrometers, 130 micrometers, 140 micrometers, 150 micrometers, etc.

[0026] By making the width of the first connecting line 211 50 microns to 150 microns, the resistance of the first connecting line 211 can be reduced to reduce current loss. At the same time, the width of the first connecting line 211 is within a suitable range, which can reduce the amount of silver paste used, thereby reducing costs. When the width of the first connecting line 211 is too wide, it will also block the main body 1, affecting the light-receiving area of ​​the back contact battery cell. When the width of the first connecting line 211 is too narrow, the loss when transmitting current is high. Therefore, when the width of the first connecting line 211 is 50 microns to 150 microns, it can reduce current loss while reducing costs and improving the efficiency of the back contact battery cell, which is more in line with actual usage needs.

[0027] like Figure 2As shown, in a possible implementation manner, the distance between the first connection line 211 and the adjacent second connection line 212 is 300 microns to 400 microns. The distance between the first connection line 211 and the second connection line 212 can be 300 microns, 310 microns, 320 microns, 330 microns, 340 microns, 350 microns, 360 microns, 370 microns, 380 microns, 390 microns, 400 microns, etc.

[0028] By making the distance between the first connection line 211 and the second connection line 212 300 microns to 400 microns, it is helpful to improve the ability of the back contact cell to collect current at the edge position. When the distance between the first connection line 211 and the second connection line 212 is too large, the transmission distance of the current increases, resulting in increased current loss during the transmission process. When the distance between the first connection line 211 and the second connection line 212 is too small, uneven current distribution is likely to occur, and the risk of short circuit will increase. Therefore, the distance between the first connection line 211 and the adjacent second connection line 212 is 300 microns to 400 microns.

[0029] like Figure 2 As shown, in a possible implementation, along the length direction Y of the back contact cell, the spacing between the auxiliary grids 22 located on opposite sides of the second connection segment 4 is d, and the width c of the second connection segment 4 satisfies: d-380 microns ≤ c ≤ d-300 microns. The width c of the second connection segment 4 can be d-380 microns, d-370 microns, d-360 microns, d-350 microns, d-340 microns, d-330 microns, d-320 microns, d-310 microns, d-300 microns, etc.

[0030] By making the spacing between the second connection segment 4 and the auxiliary grid 22 satisfy the relationship of d-380 microns ≤ c ≤ d-300 microns, the width of the second connection segment 4 can be increased to reduce the resistance of the second connection segment 4, thereby reducing the current loss. At the same time, the second connection segment 4 can also have a sufficient spacing with the adjacent auxiliary grid 22 to reduce the possibility of short circuit between the second connection segment 4 and the auxiliary grid 22, thereby improving the stability and efficiency of the back contact battery cell, which is more in line with actual use requirements.

[0031] In a possible implementation, the spacing between the auxiliary grids 22 connected to the same connection line 21 may also be d. Such a configuration is conducive to uniform distribution of the auxiliary grids 22 in the main body, thereby facilitating improvement of current collection efficiency.

[0032] like Figure 2As shown, in a possible implementation manner, the width of the second connecting segment 4 may be 100 μm to 200 μm. The width of the second connecting segment 4 may be 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, etc.

[0033] When the width of the second connecting section 4 is too small, the resistance of the second connecting section 4 is relatively large. According to Joule's law: , where Q is heat, I is current, R is resistance, and t is time. When the resistance of the second connecting segment 4 increases, the heat per unit time will increase, so the current loss will increase, thereby affecting the efficiency of the back contact cell. When the width of the second connecting segment 4 is too large, the cost of materials such as silver paste increases, and the welding difficulty increases. A second connecting segment 4 that is too wide will also affect the light-receiving area of ​​the back contact cell, thereby reducing the efficiency of the back contact cell. Moreover, when the width of the second connecting segment 4 is too large, it is easy to contact the adjacent sub-grid 22, causing the back contact cell to be prone to short circuit. Therefore, the width of the second connecting segment 4 can be between 100 microns and 200 microns. While reducing current loss, it can also reduce costs and improve the efficiency of the back contact cell, which is more in line with actual usage needs.

[0034] like Figure 2 As shown, in a possible implementation, the width b of the first connecting line 211 and the width c of the second connecting section 4 satisfy c>b.

[0035] The second connecting segment 4 is used to lead the current of the first connecting segment 212a. By making the width of the second connecting segment 4 larger than the width of the first connecting line 211, the resistance of the second connecting segment 4 can be further reduced, which is beneficial to reduce the current loss during the current transmission process, thereby improving the efficiency of the back contact battery cell.

[0036] like Figure 2 As shown, in a possible implementation, the auxiliary gate 22 includes a first auxiliary gate 221 and a second auxiliary gate 222, the first auxiliary gate 221 is electrically connected to the first connection line 211, and the second auxiliary gate 222 is electrically connected to the second connection line 212. The width of the first auxiliary gate 221 is e, the width of the second auxiliary gate 222 is f, and e>f.

[0037] The first sub-grid 221 is connected to the first connecting section 212a located at the edge of the back contact battery cell, and is used to collect the current at the edge of the back contact battery cell. By making the width of the first sub-grid 221 larger than the width of the second sub-grid 222, the resistance of the first sub-grid 221 can be reduced, thereby reducing current loss and improving the current collection capability of the first sub-grid 221 for the edge of the back contact battery cell. Therefore, the graying of the edge of the back contact battery in the EL test can be improved.

[0038] In a possible implementation, the width of the first sub-gate 221 is 10 micrometers to 30 micrometers. The width of the first sub-gate 221 can be 10 micrometers, 12 micrometers, 14 micrometers, 16 micrometers, 18 micrometers, 20 micrometers, 22 micrometers, 24 micrometers, 26 micrometers, 28 micrometers, 30 micrometers, etc.

[0039] When the width of the first auxiliary grid 221 is too small, the resistance of the first auxiliary grid 221 is relatively large, so the current loss is large, resulting in a decrease in the efficiency of the back contact battery. When the width of the first auxiliary grid 221 is too large, the cost of the first auxiliary grid 221 increases, and it is easy to contact with other grid lines 2, resulting in a short circuit in the back contact battery. Therefore, the width of the first auxiliary grid 221 is 10 microns to 30 microns, which can improve the current collection capacity of the first auxiliary grid 221, reduce current loss, and reduce costs and improve the efficiency of the back contact battery.

[0040] In a possible implementation, the width of the first connection segment 212a is 14 to 16 microns, and the width of the second sub-gate 222 is 8 to 16 microns. The width of the first connection segment 212a may be 14.0 microns, 14.2 microns, 14.4 microns, 14.6 microns, 14.8 microns, 15.0 microns, 15.2 microns, 15.4 microns, 15.6 microns, 15.8 microns, 16.0 microns, etc. The width of the second sub-gate may be 8 microns, 9 microns, 10 microns, 11 microns, 12 microns, 13 microns, 14 microns, 15 microns, 16 microns, etc.

[0041] The first connection segment 212a can be used as a main grid or a component of the main grid, and is used to lead out the current collected by the auxiliary grid 22. When the width of the first connection segment 212a is too small, the resistance of the first connection segment 212a will increase, and the heat generated when transmitting current will increase, thereby increasing the current loss. When the width of the first connection segment 212a is too large, the first connection segment 212a will block a large area of ​​the main body 1, which will affect the light receiving area of ​​the back contact battery cell, resulting in a lower efficiency of the back contact battery cell. By making the width of the first connection segment 212a 14 microns to 16 microns, while reducing the current loss, the shielding of the first connection segment 212a on the main body 1 can also be reduced, which is beneficial to improve the efficiency of the back contact battery cell.

[0042] The width of the second sub-grid 222 is 8 micrometers to 16 micrometers, which can improve the current collection capability of the second sub-grid 222 , thereby facilitating the improvement of the efficiency of the back contact solar cell and better meeting the actual use requirements.

[0043] In a possible implementation, the width of the first connection line 211 is 75 micrometers, and the width of the second connection segment 4 is 100 micrometers. That is, the width of the second connection segment 4 is greater than the width of the first connection line 211, the width of the first connection line 211 is greater than the width of the first auxiliary grid 221, and the width of the first auxiliary grid 221 is greater than the width of the second auxiliary grid 222.

[0044] In the related art, the width of the first connection line 211 and the width of the second connection segment 4 are usually the same as the width of the first connection segment 212a, and the width of the first sub-grid 221 and the second sub-grid 222 are also the same. The first connection line 211 located at the edge needs to converge the current to the second connection line 212 with the same polarity. The current collected by the second connection line 212 can be led out through the connection part 3 and the welding strip. The transmission distance of the current in the first connection line 211 is long, and the current is large. Therefore, the current loss generated when the current is transmitted in the first connection line 211 is also relatively large. When the back contact cell is tested for EL, it will turn gray at the edge, that is, the CTM performance of the back contact cell is poor, and the efficiency of the back contact cell is low.

[0045] In the solution provided by the embodiment of the present application, the resistance of the first connection line 211, the second connection segment 4 and the first auxiliary grid 221 can be reduced by thickening the first connection line 211, the second connection segment 4 and the first auxiliary grid 221. According to Joule's law, when the resistance decreases, the heat generated per unit time decreases. Therefore, by thickening the first connection line 211, the second connection segment 4 and the first auxiliary grid 221, the loss of current in the transmission process can be reduced, thereby ensuring the uniformity of EL imaging, improving the graying of the edge of the back contact cell during EL testing, thereby improving the CTM of the back contact cell and improving the efficiency of the back contact cell. The second connection segment 4 is used as a through line of the back contact cell to converge the current of the first connection line 211 to the second connection line 212, and lead the current out through the connection portion 3, that is, the current of the first connection line 211 needs to be converged from the second connection segment 4 to the second connection line 212. Therefore, the second connection segment 4, which plays a convergence role, needs to be wider than the width of the first connection line 211 to reduce current loss.

[0046] The width of the first auxiliary grid 221 is greater than the width of the second auxiliary grid 222, which can improve the current collection ability of the first auxiliary grid 221 for the edge position of the back contact battery cell. At the same time, by increasing the width of the first auxiliary grid 221, the resistance of the first auxiliary grid 221 can also be reduced, thereby reducing the heat generated during the current transfer process to reduce the current loss. By using a first connecting line 211 and a second connecting segment 4 with a larger width, the loss of current during the transfer process can be further reduced, which is conducive to improving the efficiency of the back contact battery cell. The second connecting line 212 can also include a third connecting segment 212d, the third connecting segment 212d is at least arranged at one end of the first connecting segment 212a, and the width of the third connecting segment 212d is greater than the width of the first connecting segment 212a, and in a possible embodiment, the width of the third connecting segment 212d can be greater than the width of the first connecting line 211, and the width of the third connecting segment 212d is greater than the width of the second connecting segment 4.

[0047] By providing the third connecting section 212d at at least one end of the first connecting section 212a, the second connecting line 212 can be formed into a structure with a wider end and a narrower middle. Such a design is conducive to improving the current collection and transmission capabilities of the gate line 2 for the edge position of the back contact battery cell, thereby helping to improve the efficiency of the back contact battery cell and better meet the actual use requirements.

[0048] An embodiment of the present application also provides a back-contact battery assembly, which includes at least one back-contact battery cell. The back-contact battery cell can be the back-contact battery cell involved in any of the above embodiments. Since the back-contact battery cell has the above technical effects, the back-contact battery assembly including the back-contact battery cell also has the corresponding technical effects, which will not be repeated here.

[0049] The back contact battery assembly may also include structures such as a first cover plate, a second cover plate, a first adhesive film and a second adhesive film. A plurality of back contact battery cells are electrically connected to form a back contact battery string, and a plurality of back contact battery strings are electrically connected to form a back contact battery array. Along the thickness direction of the back contact battery assembly, the first adhesive film and the second adhesive film are located on opposite sides of the back contact battery array. The first cover plate is located on the side of the first adhesive film away from the back contact battery array, and the second cover plate is located on the side of the second adhesive film away from the back contact battery array. The first cover plate and the second cover plate are located on the surface of the back contact battery assembly, which can protect the back contact battery assembly. The first adhesive film and the second adhesive film can play a buffering role to reduce the possibility of hidden cracks in the back contact battery cells during lamination and collision, thereby helping to increase the service life of the back contact battery assembly.

[0050] Adjacent back contact cells can be connected by welding strips, the auxiliary grid 22 is used to collect the photocurrent generated by the main body, and the connecting wire 21 is used to collect the current of the auxiliary grid 22. The connecting wire 21 is connected to the welding strip to lead out the current.

[0051] In a possible implementation, adjacent battery cells may also be connected using conductive adhesive. Conductive adhesive has good conductivity and adhesion. The conductive adhesive is applied to the electrodes of the battery cell, and then pressed and cured to form a conductive path, thereby achieving electrical connection. Connection through conductive adhesive can reduce the impact of thermal stress on the back contact battery cell during the connection process, as well as the possibility of mechanical damage, which is beneficial to improving the reliability and stability of the back contact battery assembly. In the actual production process, the solder strip can be used in combination with the conductive adhesive to save costs and improve reliability.

[0052] The first cover plate and the second cover plate have high structural strength, providing a certain mechanical strength and rigidity for the back-contact battery assembly to protect the adhesive film, back-contact battery cells, etc. inside the back-contact battery assembly, reduce the impact of environmental factors such as rain, wind, sand, and dust on the back-contact battery assembly, and reduce the possibility of corrosion, wear, and aging of the back-contact battery assembly, which is beneficial to extend the service life of the back-contact battery assembly.

[0053] When one side of the back contact cell assembly is the light receiving side and the other side is the backlight side, the first cover plate is located on the light receiving side and the second cover plate is located on the backlight side. The material of the first cover plate is a light-transmitting material, and the material of the second cover plate is a reflective material or a reflective layer is provided. Light can pass through the first cover plate and the first adhesive film to reach the back contact cell and be absorbed by the back contact cell to generate a photocurrent. Light that is not absorbed by the back contact cell can be reflected by the second cover plate after passing through the second adhesive film, so that the light can be transmitted to the back contact cell again, so that the back contact cell can absorb the light again, thereby improving the light absorption efficiency of the back contact cell, and further improving the efficiency of the back contact cell.

[0054] When both sides of the back contact cell are the light receiving sides, the materials of the first cover plate and the second cover plate are both light-transmitting materials. Such a design can help increase the light receiving area of ​​the back contact cell assembly, thereby helping to improve efficiency.

[0055] The material of the cover plate can be tempered glass, etc. It has good strength and good light transmittance. When tempered glass is used as the second cover plate, reflection can be achieved by setting a reflective film, a reflective coating, etc. on the surface of the tempered glass to improve efficiency.

[0056] The first adhesive film and the second adhesive film can be EVA adhesive film, POE adhesive film, EPE adhesive film (EVA-POE-EVA co-extruded adhesive film), etc. The adhesive film is located between the cover plate and the battery cell, and can play a role of bonding and fixing, so as to facilitate the various components of the back contact battery assembly to form a whole, and can reduce the possibility of stratification and shedding of the back contact battery assembly during use. The adhesive film can also play a sealing role, reducing the possibility of external water vapor, oxygen and other substances entering the interior of the back contact battery assembly, thereby reducing the possibility of corrosion and oxidation of the back contact battery cell and other components, which is conducive to extending the service life and reliability of the back contact battery assembly.

[0057] The adhesive film can also refract and scatter the light to a certain extent, so that the light can be better propagated and utilized inside the component, which is conducive to improving the absorption efficiency of the back contact cell for light, and is conducive to improving the efficiency of the back contact cell assembly, which is more in line with the actual use requirements. The cell provided in the embodiment of the present application is a back contact cell, and the positive and negative electrodes of the back contact cell are both arranged on the back of the main body, that is, the backlight side of the back contact cell. Such a design can reduce the shielding of the light receiving area of ​​the main body 1 by the gate line 2, which is conducive to increasing the light receiving area of ​​the main body 1, thereby helping to improve the photoelectric conversion efficiency. At the same time, since the electrodes are concentrated on the same side of the main body 1, when collecting current, the current transmission path is shorter, which is conducive to reducing the loss during the current transmission process, and can improve the filling factor and conversion efficiency of the cell to meet the actual use requirements. By arranging the electrode on the backlight side of the main body 1, the possibility of corrosion and damage of the electrode in outdoor environments can be reduced. By arranging the electrode on the backlight side, the influence of light and ultraviolet rays on the electrode can be reduced, and the speed of electrode aging and performance degradation can be reduced, which is conducive to extending the service life of the cell and improving the reliability of the cell. There are usually no electrode grid lines on the front of the back-contact cell, which can reduce the possibility of stress concentration problems caused by differences in thermal expansion coefficients, thereby reducing the possibility of cracking and damage to the back-contact cell during use.

[0058] The embodiment of the present application provides a back-contact cell and a back-contact cell assembly, wherein the back-contact cell comprises a main body 1 and a grid line 2 arranged on the main body 1, the grid line 2 comprises a connection line 21 and a subgrid 22, the connection points of which are arranged in the width direction, and the subgrid 22 is arranged in the length direction. The connection line 21 comprises two first connection lines 211, and the connection line 21 located between the first connection lines 211 is a second connection line 212. The subgrid 22 comprises a first subgrid 221 and a second subgrid 222, the first subgrid 221 is electrically connected to the first connection line 211, and the second subgrid 222 is electrically connected to the second connection line 212. The second connection line 212 has a first connection segment 212a located between the connection parts 3, and the first connection line 211 is electrically connected to the second connection line 212 of the same polarity through the second connection segment 4. The width of the first connection line 211 is greater than the width of the first connection segment 212a, and the width of the second connection segment 4 is greater than the width of the first connection segment 212a. Such a design can reduce the loss of current during the transmission process, thereby helping to improve the efficiency of the back-contact solar cell.

[0059] The above is only a specific implementation of the embodiment of the present application, but the protection scope of the embodiment of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed in the embodiment of the present application should be included in the protection scope of the embodiment of the present application. Therefore, the protection scope of the embodiment of the present application should be based on the protection scope of the claims.

Claims

1. A back contact battery cell, characterized in that: The back contact cell comprises: Body part (1); A grid line (2), the grid line (2) being arranged on the main body (1); The grid lines (2) include a plurality of connection lines (21) and a plurality of auxiliary grids (22); along the width direction (X) of the back contact battery sheet, the connection lines (21) are arranged in sequence; along the length direction (Y) of the back contact battery sheet, the auxiliary grids (22) are arranged in sequence; the connection lines (21) are electrically connected to the auxiliary grids (22); among the connection lines (21), two of the connection lines (21) are first connection lines (211), and the remaining connection lines (21) are second connection lines (212); along the width direction (X) of the back contact battery sheet, the first connection lines (211) are located at opposite sides of the back contact battery sheet, and the second connection lines (212) are located between the first connection lines (211); the back contact battery sheet further includes a connection portion (3 ), the second connecting line (212) is connected to the connecting portion (3), the second connecting line (212) comprises a first connecting segment (212a), at least a portion of the first connecting segment (212a) is located between adjacent connecting portions (3), each of the second connecting lines (212) is a first polarity connecting line (212b) and a second polarity connecting line (212c), the first polarity connecting line (212b) and the second polarity connecting line (212c) are arranged at intervals from each other, the polarity of the first connecting line (211) is the same as that of the first polarity connecting line (212b), the back contact battery sheet comprises a second connecting segment (4), the first connecting line (211) is electrically connected to the first polarity connecting line (212b) closest to the first polarity connecting line (212b) via the second connecting segment (4); The width of the first connecting section (212a) is a, the width of the first connecting line (211) is b, the width of the second connecting section (4) is c, and b>a, c>a.

2. The back contact cell according to claim 1, characterized in that: The width of the first connecting line (211) is 50 micrometers to 150 micrometers.

3. The back contact cell according to claim 1, characterized in that: The distance between the first connecting line (211) and the adjacent second connecting line (212) is 300 micrometers to 400 micrometers.

4. The back contact cell according to claim 1, characterized in that: Along the length direction (Y) of the back contact cell sheet, the spacing between the auxiliary grids (22) on two opposite sides of the second connecting section (4) is d, and the width c of the second connecting section (4) satisfies: d-380 microns ≤ c ≤ d-300 microns.

5. The back contact cell according to claim 1, characterized in that: The width of the second connecting section (4) is 100 micrometers to 200 micrometers.

6. The back contact cell according to claim 1, characterized in that: The width b of the first connecting line (211) and the width c of the second connecting section (4) satisfy: c>b.

7. The back contact cell according to any one of claims 1 to 6, characterized in that: The auxiliary grid (22) comprises a first auxiliary grid (221) and a second auxiliary grid (222), the first auxiliary grid (221) being electrically connected to the first connecting line (211), and the second auxiliary grid (222) being electrically connected to the second connecting line (212); The width of the first auxiliary grid (221) is e, the width of the second auxiliary grid (222) is f, and e>f.

8. The back contact cell according to claim 7, characterized in that: The width of the first sub-gate (221) is 10 micrometers to 30 micrometers.

9. The back contact cell according to claim 7, characterized in that: The width of the first connecting segment (212a) is 14 micrometers to 16 micrometers, and the width of the second auxiliary grid (222) is 8 micrometers to 16 micrometers.

10. A back contact battery assembly, characterized in that: The back-contact cell assembly comprises at least one back-contact cell sheet according to any one of claims 1 to 9.

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