Solar cell and photovoltaic module

Abstract

The embodiment of the present application relates to the photovoltaic field, and provides a solar cell and a photovoltaic module, the solar cell comprises: a substrate, the substrate has a first edge and a second edge, the first edge is an edge of the substrate along a first direction, and the second edge is an edge of the substrate along a second direction; two first main electrodes, the first main electrode is close to the first edge, and the first main electrode comprises: a plurality of first connecting pads; a first connecting line, the first connecting line is in contact with at least one side of the first connecting pad close to the first edge; at least two second main electrodes, the second main electrode is located between adjacent first main electrodes, and the second main electrode comprises: a plurality of second connecting pads; a second connecting line, the second connecting line is in contact with at least one second connecting pad; the first interval between the first main electrode and the adjacent second main electrode is not equal to the second interval between the adjacent second main electrodes. The solar cell and the photovoltaic module provided by the embodiment of the present application can at least improve photoelectric conversion efficiency.

Description

[0001] This application is a divisional application of the patent application filed on October 24, 2022, with application number 202211298941.9 and invention title "Solar Cell and Photovoltaic Module". Technical Field

[0002] This application relates to the photovoltaic field, and in particular to a solar cell and a photovoltaic module. Background Technology

[0003] Factors affecting the performance of solar cells (such as photoelectric conversion efficiency) include optical losses and electrical losses. Optical losses include reflection losses from the front surface of the cell, shading losses from the contact grid lines, and non-absorption losses in the long wavelength range. Electrical losses include photogenerated carrier recombination on the semiconductor surface and within the cell, contact resistance between the semiconductor and metal grid lines, and contact resistance between the metal and semiconductor.

[0004] In solar cells, sub-grids and main grids are used to collect and output the current generated by the cells, and the current generated by the cells is transmitted to the module end through pads on the main grid. However, the collection capacity of solar cells in the prior art is relatively weak, which affects the improvement of the photoelectric conversion efficiency of solar cells. Summary of the Invention

[0005] This application provides a solar cell and a photovoltaic module, which at least helps to improve the photoelectric conversion efficiency of the solar cell.

[0006] According to some embodiments of this application, one aspect of this application provides a solar cell, comprising: a substrate having a first edge and a second edge, the first edge being an edge of the substrate along a first direction, and the second edge being an edge of the substrate along a second direction; a passivation layer located on the substrate; a plurality of sub-electrodes spaced apart on the substrate along the second direction, the sub-electrodes extending along the first direction and penetrating the passivation layer to contact the substrate; two first main electrodes located on the surface of the passivation layer, the first main electrodes being close to the first edge, the first main electrodes comprising: a plurality of first connecting pads spaced apart along the second direction; a first connecting line directly contacting at least one first connecting pad on the side close to the first edge; the first connecting line comprising connected first connecting segments and second connecting segments. The second connecting segment extends in the same direction as the second direction; the first connecting segment is in direct contact with the first connecting pad; wherein, the first connecting segment refers to the first connecting line located between the first first connecting pad and the adjacent second edge, and the second connecting segment refers to the first connecting line located between the first first connecting pad and the last first connecting pad; at least two second main electrodes are located on the surface of the passivation layer, and the second main electrodes are located between adjacent first main electrodes, the second main electrodes comprising: a plurality of second connecting pads spaced apart along the second direction; a second connecting line, the second connecting line contacting at least one second connecting pad; the first spacing between the second connecting segment and the adjacent second connecting line is not equal to the second spacing between the adjacent second connecting lines.

[0007] In some embodiments, along a first direction, the secondary electrode contacts the side of the first connection pad away from the first edge.

[0008] In some embodiments, the first spacing is greater than the second spacing.

[0009] In some embodiments, the first spacing is smaller than the second spacing.

[0010] In some embodiments, a chamfer is provided at the junction of the first edge and the second edge, the first main electrode is close to the chamfer along the second direction, and the first first connecting pad and / or the last first connecting pad is located in the edge region of the chamfer outside the second direction.

[0011] In some embodiments, the first connecting segment is located near the outside of the chamfer along the first direction, and the second connecting segment is connected to the first connecting segment, wherein the cross-sectional area of ​​the first connecting segment is greater than the cross-sectional area of ​​the second connecting segment.

[0012] In some embodiments, along the second direction, the length between the end of the first first connecting pad and the edge of the chamfer along the second direction is less than or equal to the gate spacing between adjacent sub-electrodes.

[0013] In some embodiments, along the second direction, the first distance between the first first connecting pad and the adjacent second edge is greater than the second distance between the first second connecting pad and the adjacent second edge.

[0014] In some embodiments, the area of ​​any first connecting pad is greater than the area of ​​the second connecting pad.

[0015] In some embodiments, along a first direction, the cross-sectional area of ​​the secondary electrode closer to the first edge is larger than the cross-sectional area of ​​the secondary electrode farther from the first edge.

[0016] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, including: a battery string, which is formed by connecting multiple solar cells as described in the above embodiments; an encapsulation layer for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulation layer away from the battery string.

[0017] The technical solution provided in this application has at least the following advantages:

[0018] In the technical solution provided in this application embodiment, the first main electrode includes a first connecting pad and a first connecting line, and the second main electrode includes a second connecting pad and a second connecting line. By setting thinner first and second connecting lines, the effective light-shielding area can be reduced, while resistance loss is decreased, thereby increasing the total power of the component. Furthermore, since the first and second connecting lines constituting the main gate are more densely distributed, there can be more contact points between the main gate and the fine gate. The current conduction path at the microcracks and cracks in the silicon wafer is more optimized, thus greatly reducing losses caused by microcracks and improving production line yield. The first connecting line contacts at least one first connecting pad near the first edge. The closer the first connecting line is to the first edge, the stronger its ability to collect current at the first edge. Since there is at least one width of the first connecting line between the first connecting pad and the first edge, damage caused by poor stress at the edge can be avoided during soldering and lamination.

[0019] Furthermore, the first spacing between the first main electrode and the adjacent second main electrode is not equal to the second spacing between the adjacent second main electrodes. For example, if the first spacing is greater than the second spacing, the first main electrode is closer to the first edge, and the main electrodes at the edge are made more sparse. This can avoid risks such as micro-cracks in the solar cell during welding and lamination. Alternatively, if the first spacing is less than the second spacing, the first and second main electrodes at the edge are more densely packed, resulting in a shorter current path from the secondary electrode to the main electrode, thereby reducing losses and improving the electrode's ability to collect current at the edge. Attached Figure Description

[0020] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a solar cell structure provided in an embodiment of this application;

[0022] Figure 2 This is a partial structural schematic diagram of a solar cell provided in an embodiment of this application;

[0023] Figure 3 for Figure 1 A magnified view of a section at point A in the middle;

[0024] Figure 4 This is a schematic diagram of another structure of a solar cell provided in an embodiment of this application;

[0025] Figure 5 This is a schematic diagram of yet another structure of a solar cell provided in an embodiment of this application;

[0026] Figure 6 This is a schematic diagram of the structure of the first main electrode in a solar cell provided in an embodiment of this application;

[0027] Figure 7 This is a schematic diagram of another structure of the first main electrode in a solar cell provided in an embodiment of this application;

[0028] Figure 8 This is a schematic diagram of a structure of a secondary electrode in a solar cell provided in an embodiment of this application;

[0029] Figure 9 This is a schematic diagram of another structure of a solar cell provided in an embodiment of this application;

[0030] Figure 10 This is a schematic diagram of another partial structure of a solar cell provided in an embodiment of this application;

[0031] Figure 11 This is a schematic diagram of a photovoltaic module provided in an embodiment of this application. Detailed Implementation

[0032] As can be seen from the background technology, the photoelectric conversion efficiency of existing solar cells is not good.

[0033] Analysis reveals that one reason for the poor photoelectric conversion efficiency of existing solar cells is that, due to limitations in the refining process of monocrystalline silicon substrates, monocrystalline silicon rods can currently only be made into round shapes. After the silicon rods are produced, they are sliced, meaning the cross-section of the silicon rod is cut into monocrystalline silicon wafers (the area is calculated to maximize the illumination area within a unit, while also saving silicon rod material and facilitating cell and module production). A chamfer is often placed at the junction of the first and second edges of the substrate to reduce external stress on the silicon wafer and prevent micro-damage to the edges. Simultaneously, to ensure that the solder ribbon does not extend beyond the chamfer during welding, a certain distance must be maintained between the solder joint and the chamfer, resulting in an excessively long carrier transport path in the chamfered area, leading to increased transport losses. Furthermore, if the solder joint or solder ribbon is close to the edge of the solar cell, microcracks may be caused during subsequent lamination, affecting the performance of the solar cell.

[0034] In the solar cell provided in this application embodiment, the first main electrode includes a first connecting pad and a first connecting wire, and the second main electrode includes a second connecting pad and a second connecting wire. By setting thinner first and second connecting wires, the effective shading area can be reduced, while resistance loss is decreased, thereby increasing the total power of the module. Furthermore, because the first and second connecting wires constituting the main grid are more densely distributed, there are more contact points between the main grid and the fine grid, and the current conduction path at the microcracks and cracks in the silicon wafer is more optimized. Therefore, the loss caused by microcracks is greatly reduced, which is beneficial to increasing the yield of the production line. The first connecting wire contacts at least one first connecting pad near the first edge. The closer the first connecting wire is to the first edge, the stronger its ability to collect current at the first edge. Moreover, there is at least one width of the first connecting wire between the first connecting pad and the first edge, which can avoid breakage problems caused by poor stress at the edge during welding and lamination. In addition, the first spacing between the first main electrode and the adjacent second main electrode is not equal to the second spacing between the adjacent second main electrodes. For example, if the first spacing is greater than the second spacing, the first main electrode is closer to the first edge, and the main electrodes at the edge are made more sparse. This can avoid risks such as micro-cracks in the solar cell during welding and lamination. Alternatively, if the first spacing is less than the second spacing, the first and second main electrodes at the edge are made more densely packed, resulting in a shorter path for current from the secondary electrode to the main electrode, thereby reducing losses and improving the electrode's ability to collect current at the edge.

[0035] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0036] Figure 1 This is a schematic diagram of a solar cell structure provided in an embodiment of this application; Figure 2 This is a partial structural schematic diagram of a solar cell provided in an embodiment of this application; Figure 3 for Figure 1 A magnified view of a section at point A in the middle; Figure 4 This is a schematic diagram of another structure of a solar cell provided in an embodiment of this application; Figure 5 This is a schematic diagram of yet another structure of a solar cell provided in an embodiment of this application; Figure 6 This is a schematic diagram of the structure of the first main electrode in a solar cell provided in an embodiment of this application; Figure 7 This is a schematic diagram of another structure of the first main electrode in a solar cell provided in an embodiment of this application; Figure 8 This is a schematic diagram of a structure of a secondary electrode in a solar cell provided in an embodiment of this application; Figure 9 This is a schematic diagram of another structure of a solar cell provided in an embodiment of this application; Figure 10 This is a schematic diagram of another partial structure of a solar cell provided in an embodiment of this application.

[0037] According to some embodiments of this application, reference is made to Figures 1-10The solar cell includes: a substrate 100 having a first edge 101 and a second edge 102, the first edge 101 being the edge of the substrate 100 along a first direction X, and the second edge 102 being the edge of the substrate 100 along a second direction Y; a passivation layer located on the substrate 100; a plurality of sub-electrodes 120 spaced apart on the substrate 100 along the second direction Y, the sub-electrodes 120 extending along the first direction X and penetrating the passivation layer to contact the substrate; and two first main electrodes 130 located on the surface of the passivation layer, the first main electrodes 130 being close to the first edge 101, and the first main electrodes 130 including a plurality of spaced edges along the second direction Y. The system comprises: a first connecting pad 131 spaced apart; a first connecting line 132, the first connecting line 132 contacting at least one first connecting pad 131 on the side near the first edge 101; at least two second main electrodes 140 located on the surface of the passivation layer, the second main electrodes 140 being located between adjacent first main electrodes 130, the second main electrode 140 comprising: a plurality of second connecting pads 141 spaced apart along a second direction Y; a second connecting line 142, the second connecting line 142 contacting at least one second connecting pad 141; and a first spacing m between the first main electrode 130 and an adjacent second main electrode 140 not equal to a second spacing n between adjacent second main electrodes 140.

[0038] In some embodiments, the solar cell can be a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell, or a multi-component compound solar cell. Specifically, the multi-component compound solar cell can be a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenide solar cell, or a perovskite solar cell. The solar cell can also be any one of the following: PERC cell (Passivated Emitter and Rear Cell), PERT cell (Passivated Emitter and Rear Totally-diffused Cell), TOPCon cell (Tunnel Oxide Passivated Contact), or HIT / HJT cell (Heterojunction Technology). Figure 2 The structure of the solar cell shown is used as an example.

[0039] The substrate 100 is a region that absorbs incident photons to generate photogenerated carriers. In some embodiments, the substrate 100 is a silicon substrate, which may include one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 100 may also be silicon carbide, organic materials, or multi-component compounds. Multi-component compounds may include, but are not limited to, materials such as perovskite, gallium arsenide, cadmium telluride, and copper indium selenide. Exemplarily, in the embodiments of this application, the substrate 100 is a monocrystalline silicon substrate.

[0040] In some embodiments, the front side of the substrate 100 is a light-receiving surface that absorbs incident light, and the back side of the substrate 100 is a backlighting surface. The substrate 100 contains doped elements, which are either N-type or P-type. N-type elements can be group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As), while P-type elements can be group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In). For example, when the substrate 100 is a P-type substrate, its internal doped element type is P-type. Similarly, when the substrate 100 is an N-type substrate, its internal doped element type is N-type.

[0041] In some embodiments, the substrate 100 includes a first surface 104 and a second surface 105 opposite to each other. The first surface 104 of the substrate has an emitter 106, which has a different doping element type than the substrate 100. The surface of the emitter 106 may have a textured surface to reduce the reflectivity of the first surface 104 of the substrate 100 to incident light, thereby increasing the light absorption and utilization rate.

[0042] Furthermore, the first direction X and the second direction Y can be perpendicular to each other, or they can have an angle of less than 90 degrees, such as 60 degrees, 45 degrees, or 30 degrees, as long as the first direction X and the second direction Y are not in the same direction. For ease of explanation and understanding, this embodiment uses the example of the first direction X and the second direction Y being perpendicular. In specific applications, the angle between the first direction X and the second direction Y can be adjusted according to actual needs and application scenarios; this embodiment does not impose any restrictions on this.

[0043] In some embodiments, a chamfer 103 is provided at the junction of the first edge 101 and the second edge 102. The first main electrode 130 is close to the chamfer 103. Along the second direction Y, the first and / or last first connecting pad 131 is located in the edge region of the chamfer 103 outside the second direction Y. Thus, the first and / or last first connecting pad 131 are not located in the region directly opposite the chamfer 103, which can avoid microcracks and micro-cracks at the chamfer 103 during welding or lamination. Since the first connecting pad 131 is close to the chamfer 103, the current collected at the chamfer 103 can be collected by the solder ribbon with the shortest transmission path, reducing path loss and improving the cell efficiency of the solar cell. Specifically, refer to Figure 1 The distance between the side of the first connecting pad 131 closest to the second edge 102 and the side of the chamfer 103 facing the first connecting pad is small or adjacent. Thus, the first connecting pad 131 can be considered to be located in the edge region of the chamfer 103 outside the second direction Y. Here, "small distance" can mean that the distance is less than the gate spacing between adjacent sub-electrodes 120.

[0044] In some embodiments, along the second direction Y, the length between the end of the first connecting pad 131 and the edge of the chamfer 103 along the second direction Y is less than or equal to the grid spacing between adjacent sub-electrodes 120, further illustrating that the current collected at the chamfer 103 can be collected by the solder strip with the shortest transmission path, reducing path loss and improving the cell efficiency of the solar cell.

[0045] In some embodiments, the passivation layer can be a single-layer structure or a stacked structure, and the material of the passivation layer can be one or more of the following: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide. The passivation layer may include a first passivation layer 111 and a second passivation layer 112. The first passivation layer is located on the surface of the emitter 106 away from the substrate 100, and the first passivation layer 111 can be regarded as a front passivation layer. The second passivation layer 112 is located on the second surface 105 of the substrate 100, and the second passivation layer 112 can be regarded as a rear passivation layer.

[0046] In some embodiments, the secondary electrode 120 is a grid line of a solar cell used to collect and summarize the current of the solar cell. The secondary electrode 120 may be sintered from a burn-through paste. The material of the secondary electrode may be one or more of aluminum, silver, gold, nickel, molybdenum, or copper. In some cases, the secondary electrode 120 refers to fine grid lines or finger grid lines to distinguish it from the main grid lines or busbars. The secondary electrode 120 includes a first electrode 121 that penetrates the first passivation layer 111 and contacts the emitter 106; the first electrode 121 is considered the upper electrode or front electrode. The second electrode 122 penetrates the second passivation layer 112 and contacts the second surface 105 of the substrate 100; the second electrode 122 is considered the lower electrode or back electrode.

[0047] In some embodiments, the first main electrode 130 and the second main electrode 140 are regarded as the main grid of the solar cell. Here, the main grid is not a main grid in the traditional sense, but rather a bridge connecting each sub-electrode through the first connecting line 132. The solder ribbon is connected through the first connecting pad 131 for collecting current. In this way, the width of the first connecting line 132 and the second connecting line 142 can be set to be thinner, reducing the effective shading area and reducing resistance loss, thereby increasing the total power of the module. The first main electrode 130 and the second main electrode 140 can be arranged more densely, shortening the path of current through the fine grid, thereby improving the photoelectric conversion efficiency of the solar cell. The thinner first connecting line 132 and the first connecting pad 131 can also avoid the risk of microcracks and cracks in the silicon wafer. Thus, the first main electrode 130 is set at the edge of the solar cell with microcracks and cracks, improving the current collection capability at the edge and making the current collection or conduction path more optimized.

[0048] In some embodiments, the first connecting line 132 is electrically connected to each sub-electrode 120 for collecting the current of each sub-gate. The width of the first connecting line 132 is relatively thin, ranging from 20μm to 200μm. Preferably, the width of the connecting line 114 ranges from 20μm to 150μm, specifically 28μm, 58μm, 98μm, 135μm, or 150μm, which can reduce the shading area and reduce the shadow loss of the contact gate line.

[0049] In some embodiments, the port of the first connecting line 132 near the second edge 102 is closed, unlike common harpoon connecting lines. That is, the first connecting line 132 has only one connecting line connecting to each of the first connecting pads 131. While harpoon connecting lines can increase the contact points and transmission paths between the main electrode and the sub-electrode, the thinner connecting lines can lead to greater resistance damage to the main electrode, affecting battery efficiency. Using only one connecting line, compared to a harpoon connecting line consisting of at least two connecting lines, reduces paste costs and improves subsequent solder ribbon alignment. Specifically, the port near the second edge 102 does not contact the first connecting pad 131; the first connecting pad 131 contacts the area outside the port of the first connecting line 132. Thus, when there is a chamfer 103 at the substrate corner, the first connecting pad 131 is located in the area not directly opposite the chamfer 103, and the first connecting line 132 can be located in the area directly opposite the chamfer 103, thereby collecting current at the chamfer 103 and reducing the carrier transport path in the chamfer 103 area to reduce transport losses.

[0050] In some embodiments, the first spacing m is greater than the second spacing n, and the first main electrode 130 is close to the first edge 101. The main electrodes at the edge are made relatively sparse, which can avoid risks such as micro-cracks in the battery cell during welding and lamination. The ratio P of the first spacing m to n ranges from 1.5 ≥ P > 1, further, 1.3 ≥ P > 1.1, 1.45 ≥ P > 1.05, 1.38 ≥ P > 1, or 1.5 ≥ P > 1.2. In other embodiments, the first spacing m is less than the second spacing n, ensuring that the first main electrode 130 and the second main electrode 140 are relatively dense at the edge, resulting in a shorter current path from the secondary electrode 120 to the main electrode, thereby reducing losses and improving the electrode's ability to collect current at the edge. The ratio P of the first spacing m to n ranges from 1 > P ≥ 0.5, further, 0.8 > P ≥ 0.5, 0.9 ≥ P ≥ 0.7, 0.98 ≥ P ≥ 0.53, or 0.8 ≥ P ≥ 0.5.

[0051] In some embodiments, the first connecting line 132 and the second connecting line 142 are made of the same material, that is, the first connecting line 132 and the second connecting line 142 are formed under the same manufacturing process.

[0052] In some embodiments, the first connecting pad 131 can be considered as the contact point where the first main electrode 130 contacts the solder strip. The first connecting pad 131 may or may not contact the secondary electrode, but may be electrically connected to the secondary electrode through the first connecting line 132. Similarly, the second connecting pad 141 is the contact point where the second main electrode 140 contacts the solder joint.

[0053] In some embodiments, along the second direction Y, the first distance between the first first connecting pad 131 and the adjacent second edge 102 is greater than the second distance between the first second connecting pad 141 and the adjacent second edge 102. Since the junction of the first edge 101 and the second edge 102 of the substrate has a chamfer 103, and the position of the first connecting pad 131 is far from the second edge 102, setting the second connecting pad 141 closer to the second edge 102 than the first connecting pad 131 can shorten the current transmission path at the second edge 102 and improve the current collection capability of the second edge 102.

[0054] In some embodiments, the area of ​​any first connecting pad 131 is larger than the area of ​​the second connecting pad 141. When the area of ​​each first connecting pad 131 located at the edge is larger, it can serve as a reference for solder ribbon alignment, avoiding solder ribbon misalignment with the first main electrode 130. The larger area of ​​the first connecting pad 131 can also relieve the pressure on the solder ribbon and improve the edge current collection capability. The smaller area of ​​the second connecting pad 141 reduces the shading area.

[0055] In some embodiments, reference Figure 3The first connecting line 132 contacts at least one first connecting pad 131 on the side near the first edge 101. The closer the first connecting line 132 is to the first edge 101, the stronger its ability to collect current at the first edge 101. Furthermore, the first connecting pad 131 is at least one width of the first connecting line 132 away from the first edge 101, thus preventing breakage due to poor stress at the edge during soldering and lamination. When the first connecting pad 131 contacts the secondary electrode, the secondary electrode contacts the side of the first connecting pad 131 away from the first edge 101. This allows the current collected by the secondary electrode to be directly collected by the first connecting pad and converged onto the solder strip, reducing the current transmission path.

[0056] In some embodiments, reference Figures 3-7 The first connecting line 132 includes a first connecting segment 134 and a second connecting segment 135 located on the outer side of the chamfer 103 along the first direction X. The second connecting segment 135 is connected to the first connecting segment 134, and the cross-sectional area of ​​the first connecting segment 134 is larger than the cross-sectional area of ​​the second connecting segment 135. Alternatively, the first cross-sectional area of ​​the first connecting line 132 located between the first first connecting pad 131 and the adjacent second edge 102 is larger than the second cross-sectional area of ​​the first connecting line 132 located between the first first connecting pad 131 and the last first connecting pad 131. The width of the first connecting line 132 located between the second edge 102 and the first connecting pad 131 is larger, which can alleviate the welding stress of the first connecting pad 131 and make good contact between the solder strip and the first main electrode 130. In addition, the wider first connecting line 132 can alleviate the pressure at the collection point of the first connecting pad 131 and improve the carrier transport capacity. The wider first connecting line 132 has a larger transport area for collecting current.

[0057] It is understood that the first connecting segment 134 refers to the first connecting line 132 located between the first first connecting pad 131 and the adjacent second edge 102, and the second connecting segment 135 refers to the first connecting line 132 located between the first first connecting pad 131 and the last first connecting pad 131.

[0058] The cross-sectional area refers to the product of the width and the height. However, in order to avoid the risk of microcracks or cracks in the battery cell due to different stresses at different parts of the cell during subsequent connection with the solder strip or lamination process, the height of the first connecting line 132 is usually set to be the same. Thus, the first cross-sectional area is greater than the second cross-sectional area. This can be regarded as the first width of the first connecting line 132 located between the first first connecting pad 131 and the adjacent second edge 102 being greater than the second width of the first connecting line 132 located between the first first connecting pad 131 and the last first connecting pad 131.

[0059] In other embodiments, to avoid the risk of microcracks in the first connecting line 132 near the edge, the height of the first connecting line 132 located between the first first connecting pad 131 and the second edge 102 may be slightly smaller than the height of the first connecting line 132 located between the first first connecting pad 131 and the last first connecting pad 131. Similarly, it can be deduced that the first width of the first connecting line 132 located between the first first connecting pad 131 and the second edge 102 is greater than the second width of the first connecting line 132 located between the first first connecting pad 131 and the last first connecting pad 131. The larger width of the first connecting line 132 located at the second edge 102 and the first first connecting pad 131 can alleviate the welding stress of the first connecting pad 131, so as to form a good contact between the solder strip and the first main electrode 130; in addition, the wider first connecting line 132 can alleviate the pressure at the collection point of the first connecting pad 131, improve the carrier transport capacity, and the wider first connecting line 132 has a larger transport area for collecting current.

[0060] In some embodiments, the difference between the first cross-sectional area and the second cross-sectional area is proportional to the distance S between the first connecting pad 131 and the adjacent second edge 102. When the distance S between the first connecting pad 131 and the adjacent second edge 102 is large, the first cross-sectional area is also large, that is, the first width is also large, resulting in a larger current transmission area, thereby alleviating collection pressure and improving battery performance. The difference between the first cross-sectional area and the second cross-sectional area can be considered as the difference between the first width and the second width. The difference between the first width and the second width is less than 100 μm, and further, the difference between the first width and the second width is less than 80 μm. Specifically, the difference between the first width and the second width can be 15 μm, 39 μm, 68 μm, or 80 μm. Thus, the difference between the first width and the second width satisfies the following conditions: the width of the first connecting segment 134 is large, the carrier collection capacity of the second edge is better, and the shielding area is appropriate, reducing optical loss; the cross-sectional area of ​​the second connecting segment 135 is appropriate, the conductivity is good, and the resistance loss is small.

[0061] Specifically, the first width ranges from 20μm to 200μm, preferably from 20μm to 150μm, and can specifically be 28μm, 58μm, 98μm, 135μm, or 150μm. This allows the width of the first connecting segment 134 to reduce the shading area, decrease the shading loss of the contact grid line, and improve current collection capability. The second width ranges from 20μm to 100μm, preferably from 20μm to 80μm, and can specifically be 28μm, 39μm, 52μm, 71μm, or 80μm. This allows the second connecting segment 135 to have an appropriate cross-sectional area, good conductivity, and low resistance loss. The distance S between the first connecting pad 131 and the adjacent second edge 102 ranges from 3mm to 15mm, preferably from 3mm to 13mm, and can specifically be 3mm, 5.8mm, 9.4mm, or 13mm. The distance between the first connecting pad 131 and the second edge 102 is moderate, which can collect the charge carriers of the second edge 102 and avoid the risks of microcracks and damage caused during welding of the solder strip.

[0062] In some embodiments, reference Figures 4-7 The first connecting pad 131 includes two first sub-connecting pads 143 and a second sub-connecting pad 144 located between the first sub-connecting pads 143. The number of second sub-connecting pads 144 is greater than or equal to one, and the third cross-sectional area of ​​the first connecting line 132 (second segment 137) located between the second sub-connecting pads 144 is minimized. In a specific example, refer to... Figure 7 In this example, the fourth cross-sectional area of ​​the first connecting line 132 (first segment 136) located between the first sub-connecting disk 143 and the second sub-connecting disk 144 is equal to the third cross-sectional area. The width of the first connecting line 132 in the middle region is relatively thin, which can reduce the area obstructed by the grid lines. In another specific example, the fourth cross-sectional area of ​​the first connecting line 132 located between the first sub-connecting disk 143 and the second sub-connecting disk 144 is larger than the third cross-sectional area. Thus, the first cross-sectional area is the largest, the fourth cross-sectional area is the second largest, and the third cross-sectional area is the smallest. This ensures that the obstruction area in the middle region of the substrate is small, the width of the edge region is large, and the contact between the first connecting line 132 and the sub-electrode 120 is good, thereby having a better current collection capability.

[0063] In some embodiments, the area of ​​the first sub-connecting pad 143 is larger than the area of ​​the second sub-connecting pad 144. When the area of ​​the first sub-connecting pad 143 located at the edge is larger, it can serve as a reference for solder strip alignment, avoiding solder strip misalignment between the solder strip and the first main electrode 130; the larger area of ​​the first sub-connecting pad 143 can also alleviate the pressure on the solder strip, while improving the edge current collection capability.

[0064] In some embodiments, the second connection line 142 closes at the port near the second edge 102, and the cross-sectional area of ​​the first connection line 132 is greater than or equal to the cross-sectional area of ​​the second connection line 142. For the second main electrode 140 in the non-edge region, a narrower second connection line 142 is provided, resulting in a smaller grid line shading area for the second main electrode 140. For the first main electrode 130 in the edge region, a wider first connection line 132 is provided, increasing the cross-sectional area of ​​the electrical contact between the first connection line 132 and each sub-electrode, reducing the resistance of the first connection line 132. Compared to the thinner second connection line 142, this improves the current collection and transmission capability of the first connection line 132 near the substrate edge, thereby enhancing the overall edge current collection capability and photoelectric conversion efficiency of the solar cell.

[0065] In some embodiments, one end of the second connecting line 142 is closed near the port of the second edge 102, and the surface of the second connecting line 142 other than the port is in contact with the second connecting pad 141; Reference Figure 4 as well as Figure 5 The fifth cross-sectional area of ​​the second connecting line 142 (fifth segment 145) located between the second connecting pad 141 and the adjacent second edge 102 is larger than the sixth cross-sectional area of ​​the second connecting line 142 (sixth segment 146) located between the second connecting pads 141. The technical concept and the technical effect achieved by the fifth cross-sectional area being larger than the sixth cross-sectional area are the same as or similar to the technical concept and the technical effect achieved by the first cross-sectional area being larger than the second cross-sectional area, and will not be elaborated further here.

[0066] In some embodiments, reference Figure 8 Along the first direction X, the cross-sectional area of ​​the secondary electrode 120 near the first edge 101 is larger than that of the secondary electrode 120 far from the first edge 101, so as to improve the current collection and transmission capability of the secondary electrode 120 at the first edge 101.

[0067] In some embodiments, the solar cell is a back-contact cell, such as an IBC (Interdigitated back contact) cell, see reference. Figure 9 and Figure 10The back contact battery includes: a substrate; a third passivation layer 115 located on a first surface 104 of the substrate; a first doped region 118 and a second doped region 117 located on a second surface 105 of the substrate; a fourth passivation layer 116 located on the surface of the substrate 100 of the first doped region 118 and the second doped region 117; a first electrode 121 connected to the first doped region 118 through the fourth passivation layer 116; and a second electrode 122 connected to the second doped region 117 through the fourth passivation layer 116. In some embodiments, the back contact battery includes: a substrate; a third passivation layer located on a first surface of the substrate; a first doped region located on a second surface of the substrate, the first doped region may have the same conductivity type as the substrate or a different conductivity type than the substrate; a tunneling oxide layer and a doped polysilicon layer located on the second surface of the substrate; a fourth passivation layer located on the surface of the first doped region and the doped polysilicon layer; a first electrode penetrating the fourth passivation layer and connected to the doped polysilicon layer; and a second electrode penetrating the fourth passivation layer and connected to the first doped region. In still some embodiments, the back contact battery includes: a substrate; a third passivation layer located on a first surface of the substrate; a tunneling oxide layer located on a second surface of the substrate; a first doped polysilicon layer and a second doped polysilicon layer; a fourth passivation layer located on the surface of the first doped polysilicon layer, the second doped polysilicon layer, and the substrate; a first electrode penetrating the fourth passivation layer and connected to the first doped polysilicon layer; and a second electrode penetrating the fourth passivation layer and connected to the second doped polysilicon layer. It is understood that the first surface 104 is the front side of the silicon substrate, the second surface 105 is the back side of the silicon substrate, the first doped region is either an N-type doped region or a P-type doped region, and the second doped region is either an N-type doped region or a P-type doped region.

[0068] It is worth noting that a "back contact battery" refers to a battery in which both the positive and negative electrodes are in contact with the structure on the back of the substrate to collect current, without involving the front of the substrate.

[0069] In some embodiments, the back contact battery includes: a substrate 100 having a first edge 101 and a second edge 102, the first edge 101 being an edge of the substrate 100 along a first direction X, and the second edge 102 being an edge of the substrate 100 along a second direction Y; a passivation layer located on the substrate 100; a plurality of sub-electrodes 120 spaced apart on the substrate 100 along the second direction Y, the sub-electrodes 120 extending along the first direction X, and the sub-electrodes penetrating the passivation layer to contact the substrate; and two first main electrodes 130 located on the surface of the passivation layer, the first main electrodes 130 being close to the first edge 101, and the first main electrodes 130 including: a plurality of edges along the second direction Y. The system comprises: first connecting pads 131 spaced apart in the Y direction; first connecting lines 132, which contact at least one first connecting pad 131 on the side near the first edge 101; at least two second main electrodes 140 located on the surface of the passivation layer and between adjacent first main electrodes 130; each second main electrode 140 comprising: a plurality of second connecting pads 141 spaced apart in the second Y direction; second connecting lines 142, which contact at least one second connecting pad 141; and a first spacing m between the first main electrode 130 and an adjacent second main electrode 140 not equal to a second spacing n between adjacent second main electrodes 140.

[0070] In some embodiments, the first electrode 121 is one of a positive electrode and a negative electrode, and the second electrode 122 is one of a positive electrode and a negative electrode. This application embodiment uses the first electrode 121 as a positive electrode and the second electrode 122 as a negative electrode as an example. The secondary electrode 120 includes the first electrode 121 and the second electrode 122 arranged at intervals along the second direction Y.

[0071] In some embodiments, reference Figure 9 The second main electrode includes: a first gate line structure 153 and a second gate line structure 154 arranged at intervals. The first gate line structure 153 is electrically connected to each first electrode 121, and the second gate line structure 154 is electrically connected to each second electrode 122. The first main electrode includes a first edge gate line 151 and a second edge gate line 152. The first edge gate line 151 is electrically connected to each first electrode 121, and the second edge gate line 152 is electrically connected to each second electrode 122. Specifically, the second main electrode adjacent to the positively polarized first edge gate line 151 is the second gate line structure 154, and the second main electrode adjacent to the negatively polarized second edge gate line 152 is the first gate line structure 153.

[0072] In some embodiments, the first grid line structure 153 and the second grid line structure 154 are staggered along the first direction X so that the distances between the first grid line structure 153 and the second grid line structure 154 and the second edge are different along the second direction Y. This reduces the consumption of conductive silver paste for metallization in the solar cell and shortens the current collection distance in the fine grid direction, thus reducing the breakage rate. Furthermore, the main grid may not be exposed to the end of the secondary electrode near the second edge, which is aesthetically pleasing, ensures adaptable lengths for the positive and negative electrodes of the cell, and avoids the risk of short circuits between electrodes of different polarities. Similarly, the first edge grid line 151 and the second edge grid line 152 are staggered along the first direction X to avoid the risk of short circuits between different secondary electrodes.

[0073] In the solar cell provided in this application embodiment, the first main electrode 130 includes a first connecting pad 131 and a first connecting line 132, and the second main electrode 140 includes a second connecting pad 141 and a second connecting line 142. By setting the first connecting line 132 and the second connecting line 142 to be thinner, the effective shading area can be reduced, and the resistance loss can be reduced, thereby increasing the total power of the module. In addition, since the first connecting line 132 and the second connecting line 142 constituting the main grid are more densely distributed, there can be more contact points between the main grid and the fine grid. The current conduction path at the microcracks and cracks in the silicon wafer is more optimized. Therefore, the loss caused by microcracks is greatly reduced, which is beneficial to increasing the output of the production line. The first connecting line 132 contacts at least one first connecting pad 131 on the side near the first edge 101. The first connecting line 132 is closer to the first edge 101, which enhances the ability of the first connecting line 132 to collect current at the first edge 101. Furthermore, there is at least the width of the first connecting line 132 between the first connecting pad 131 and the first edge 101, which can avoid the problem of breakage caused by poor stress at the edge during welding and lamination.

[0074] Furthermore, the first spacing m between the first main electrode 130 and the adjacent second main electrode 140 is not equal to the second spacing n between the adjacent second main electrodes 140. For example, if the first spacing m is greater than the second spacing n, the first main electrode 130 is closer to the first edge 101, and the main electrodes at the edge are made more sparse. This can avoid risks such as micro-cracks in the battery cell during welding and lamination. For example, if the first spacing m is less than the second spacing n, the first main electrode 130 and the second main electrode 140 at the edge are more densely packed, the current path from the secondary electrode to the main electrode is shorter, thereby reducing losses and improving the electrode's ability to collect current at the edge.

[0075] Figure 11 This is a schematic diagram of a photovoltaic module provided in an embodiment of this application.

[0076] Accordingly, embodiments of this application also provide a photovoltaic module, with reference to... Figure 11The photovoltaic module includes a battery string, which is formed by connecting multiple solar cells 20 provided in the above embodiments; an encapsulation layer 21 for covering the surface of the battery string; and a cover plate 22 for covering the surface of the encapsulation layer 21 away from the battery string. The solar cells 20 are electrically connected in a whole or in multiple segments to form multiple battery strings, and the multiple battery strings are electrically connected in series and / or parallel.

[0077] Specifically, in some embodiments, multiple battery strings can be electrically connected. The encapsulation layer 21 includes a first encapsulation layer 211 and a second encapsulation layer 212. The first encapsulation layer 211 covers one of the front or back sides of the solar cell 20, and the second encapsulation layer covers the other of the front or back sides of the solar cell 20. Specifically, at least one of the first encapsulation layer 211 or the second encapsulation layer 212 can be an organic encapsulation film such as ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene coelastomer (POE) film, or polyethylene terephthalate (PET) film. In some embodiments, the cover plate 22 can be a glass cover plate, a plastic cover plate, or a cover plate with light-transmitting function. Specifically, the surface of the cover plate 22 facing the encapsulation layer 21 can be an uneven surface, thereby increasing the utilization rate of incident light. The cover plate 22 includes a first cover plate 221 and a second cover plate 222, with the first cover plate 221 opposite to the first encapsulation layer 211 and the second cover plate 222 opposite to the second encapsulation layer 212.

[0078] While this application discloses preferred embodiments as described above, it is not intended to limit the scope of the claims. Any person skilled in the art can make various possible variations and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims. Furthermore, the embodiments and accompanying drawings in this specification are merely illustrative and do not represent the full scope of protection of the claims.

[0079] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, include: A substrate having a first edge and a second edge, the first edge being an edge of the substrate along a first direction, and the second edge being an edge of the substrate along a second direction; A passivation layer, wherein the passivation layer is located on the substrate; Multiple sub-electrodes are arranged at intervals along a second direction on the substrate, and extend along a first direction, penetrating the passivation layer and contacting the substrate; Two first main electrodes are located on the surface of the passivation layer and are close to a first edge. Each first main electrode includes: a plurality of first connecting pads spaced apart along a second direction; a first connecting line that directly contacts at least one of the first connecting pads on the side close to the first edge; the first connecting line includes a first connecting segment and a second connecting segment connected together, the second connecting segment extending in the same direction as the second direction; and the first connecting segment directly contacts the first connecting pad. Wherein, along the second direction, the first connecting segment refers to the first connecting line located between the first first connecting pad near the second edge and the adjacent second edge, and the second connecting segment refers to the first connecting line located between the first first connecting pad and the last first connecting pad; At least two second main electrodes are located on the surface of the passivation layer and between adjacent first main electrodes. Each second main electrode includes: a plurality of second connecting pads spaced apart along the second direction; and a second connecting line that contacts at least one second connecting pad. The first spacing between the second connecting segment and the adjacent second connecting line is not equal to the second spacing between the adjacent second connecting lines; The first edge and the second edge have a chamfer at their junction. The first connecting segment is located near the chamfer on the outside of the first direction. The second connecting segment is connected to the first connecting segment. The cross-sectional area of ​​the first connecting segment is larger than that of the second connecting segment.

2. The solar cell according to claim 1, characterized in that, Along the first direction, the secondary electrode contacts the side of the first connecting pad away from the first edge.

3. The solar cell according to claim 1, characterized in that, The first spacing is greater than the second spacing.

4. The solar cell according to claim 1, characterized in that, The first spacing is smaller than the second spacing.

5. The solar cell according to claim 1, characterized in that, Along the second direction, the first first connecting pad and / or the last first connecting pad are located in the edge region of the chamfer outside the second direction.

6. The solar cell according to claim 5, characterized in that, Along the second direction, the distance between the end of the first first connecting pad and the edge of the chamfer along the second direction is less than or equal to the gate spacing between adjacent sub-electrodes.

7. The solar cell according to claim 1 or 5, characterized in that, Along the second direction, the first distance between the first first connecting pad and the adjacent second edge is greater than the second distance between the first second connecting pad and the adjacent second edge.

8. The solar cell according to claim 1, characterized in that, The area of ​​any of the first connecting pads is greater than the area of ​​the second connecting pad.

9. The solar cell according to claim 1, characterized in that, Along the first direction, the cross-sectional area of ​​the secondary electrode closer to the first edge is greater than the cross-sectional area of ​​the secondary electrode farther from the first edge.

10. A photovoltaic module, characterized in that, include: A battery string, wherein the battery string is formed by connecting a plurality of solar cells as described in any one of claims 1 to 9; Encapsulation layer, the encapsulation layer being used to cover the surface of the battery string; A cover plate for covering the surface of the encapsulation layer away from the battery string.

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