Patent Description:
Performance (such as photoelectric conversion efficiency) of solar cells is affected by optical loss and electrical loss. The optical loss includes reflection loss of a front surface of the solar cell, shadow loss of contact grid lines, and non-absorption loss in longwave band, and the like. The electrical loss includes photo-generated carrier recombination on the surface and in body of the semiconductor, and loss of contact resistance between the semiconductor and the metal grid lines, and the like.

Current generated by the solar cell is collected and output through secondary grid lines and main grid lines arranged in the solar cell, and then is transmitted to an assembly end through pad sections arranged on the main grid lines. However, the solar cell has relatively weak current collection ability in the related technologies, which may affect improvement of the photoelectric conversion efficiency of the solar cell. <CIT> discloses a solar cell known from the prior art.

The subject matter of the present invention is defined in claim <NUM>. Embodiments of the disclosure provide a solar cell and a photovoltaic module, so as to at least improve the photoelectric conversion efficiency of the solar cell.

According to some embodiments, a solar cell is provided. The solar cell includes a substrate having first edges and second edges, where the first edges include two opposite edges of the substrate along a second direction and the second edges include two opposite edges of the substrate along a first direction; a passivation layer disposed on the substrate; a plurality of secondary electrodes arranged at intervals along the second direction on the substrate, where each of the plurality of secondary electrodes extends along the first direction, and penetrates through the passivation layer to be in contact with the substrate; two first main electrodes, disposed on a surface of the passivation layer, where each of the two first main electrodes is close to a corresponding first edge and includes a plurality of first sub-connection pads arranged at intervals along the second direction and a first connection wire, and the first connection wire is in contact with a side of each of at least one of the plurality of first sub-connection pads close to the corresponding first edge; and at least two second main electrodes, where the at least two second main electrodes are disposed on the surface of the passivation layer, and are disposed between the two first main electrodes, where each of the at least two second main electrodes includes a plurality of second sub-connection pads arranged at intervals along the second direction and a second connection wire, and the second connection wire is in contact with at least one of the plurality of second sub-connection pads, where a first pitch between a respective first main electrode and a second main electrode adjacent to the respective first main electrode is not equal to a second pitch between adjacent second main electrodes.

In some embodiments, in the first direction, each of at least one of the plurality of secondary electrodes is in contact with a side of a corresponding first sub-connection pad away from the corresponding first edge.

In some embodiments, the first pitch is greater than the second pitch.

In some embodiments, the first pitch is less than the second pitch.

In some embodiments, a chamfer is provided at a junction of a respective first edge and a corresponding second edge, each of the two first main electrodes is adjacent to a corresponding pair of chamfers; and in the second direction, at least one of a first of the plurality of first sub-connection pads and a last of the plurality of first sub-connection pads is located in an edge region outside a corresponding chamfer along the second direction.

In some embodiments, the first connection wire includes a first connection section close to an outside of each of the corresponding pair of chamfers in the first direction and a second connection section connected to the first connection section; wherein the first connection section has a cross-sectional area larger than a cross-sectional area of the second connection section.

In some embodiments, in the second direction, a distance between an end of the first of the plurality of first sub-connection pads close to an adjacent second edge and an edge of an adjacent chamfer facing the first sub-connection pads along the second direction is less than or equal to a grid pitch between adjacent secondary electrodes.

In some embodiments, in the second direction, a first distance between a first of the plurality of first sub-connection pads and an adjacent second edge is greater than a second distance between a first of the plurality of second sub-connection pads and the adjacent second edge in the second direction.

In some embodiments, an area of each of the plurality of first sub-connection pads is larger than an area of any of the plurality of second sub-connection pads.

In some embodiments, in the first direction, for a respective secondary electrode of the plurality of secondary electrodes, a cross-sectional area of a part of the respective secondary electrode close to the first edge is larger than a cross-sectional area of another part of the respective secondary electrode away from the first edge.

In some embodiments, the plurality of first sub-connection pads comprise two first sub-connection disks respectively close to the second edges and at least one second sub-connection disk disposed between the two first sub-connection disks; and a first cross-sectional area of a first part of the first connection wire between a respective first sub-connection disk and a second edge adjacent to the respective first sub-connection disk is larger than a second cross-sectional area of a second part of the first connection wire between the two first sub-connection disks.

In some embodiments, a difference between the first cross-sectional area and the second cross-sectional area is proportional to a spacing between the respective first sub-connection disk and the second edge adjacent to the respective first sub-connection disk.

In some embodiments, a first width of the first part of the first connection wire between the respective first sub-connection disk and the second edge adjacent to the respective first sub-connection disk is larger than a second width of the second part of the first connection wire between the two first sub-connection disks.

In some embodiments, for a same first main electrode, a third cross-sectional area of a third part of the first connection wire between two adjacent second sub-connection disks is a smallest cross-sectional area.

In some embodiments, a fourth cross-sectional area of a fourth part of the first connection wire between the respective first sub-connection disk and a second sub-connection disk adjacent to the respective first sub-connection disk is greater than or equal to the third cross-sectional area.

In some embodiments, an area of each of the two first sub-connection disks is larger than an area of any of the at least one second sub-connection disk.

In some embodiments, the first connection wire is closed at each port of ports respectively close to the second edges, and the second connection wire is closed at each port of ports respectively close to the second edges, wherein a sectional area of the first connection wire is larger than or equal to a sectional area of the second connection wire.

In some embodiments, the solar cell is a back contact cell, and the plurality of secondary electrodes comprises first electrodes and second electrodes alternatively arranged along the second direction, wherein at least two second main electrodes comprise first grid line structures and second grid line structures alternatively arranged; wherein each of the first grid line structures is electrically connected with the first electrodes, and each of the second grid line structures is electrically connected with the second electrodes.

In some embodiments, the first grid line structures and the second grid line structures are misaligned along the first direction.

Embodiments of the disclosure further provide a photovoltaic module. The photovoltaic module includes at least one cell string each including a plurality of solar cells, at least one encapsulating layer, and at least one cover plate. Each of the plurality of solar cells being a solar cell provided in any of the above embodiments. Each encapsulating layer is configured to cover a surface of the at least one cell string. Each cover plate is configured to cover a surface of a corresponding encapsulating layer of the at least one encapsulating layer facing away from the at least one cell string.

Embodiments of the disclosure has following advantageous effects.

According to the solar cell provided in embodiments of the disclosure, each first main electrode includes the first sub-connection pads and the first connection wire, and each second main electrode includes the second sub-connection pads and the second connection wire. By arranging the thinner first connection wire and the second connection wire, the effective shading area and the resistance loss can be reduced, thereby increasing the assembly total power. In addition, since the first connection wires and the second connection wires forming the main grid lines are densely distributed, more contact points between the main grid lines and the secondary grid lines can be obtained, and a current conduction path at the cracked and micro-cracked parts of the silicon wafer is more optimized, so the loss caused by micro-cracks is greatly reduced, which is beneficial to improving the output of the production line. Each first connection wire is in contact with a side of each of the at least one first sub-connection pad close to the first edge, i.e., the first connection wire is closer to the first edge, such that the ability of the first connection wire to collect the current at the first edge is enhanced. In addition, at least one width of the first connection wire is separated between the first sub-connection pad and the first edge, so that the breakage caused by poor stress at the edge can be avoided during welding and laminating.

In addition, the first pitch between the respective first main electrode and the adjacent second main electrode is not equal to the second pitch between the adjacent second main electrodes. For example, the first pitch is greater than the second pitch, the first main electrode is close to the first edge, and the main electrodes at the edges are sparsely arranged, so that the risk of micro-cracking of the solar cell can be avoided during welding and laminating. Alternatively, the first pitch is smaller than the second pitch, such that the first main electrodes and the second main electrodes at the edges are densely distributed, and a path of current from the secondary electrode to the main electrode is relatively short, thereby reducing loss and facilitating the ability of the electrode to collect current at the edge.

One or more embodiments are described as examples with reference to the corresponding figures in the accompanying drawings and the exemplary illustration does not constitute a limitation to the embodiments. Unless otherwise stated, the figures in the accompanying drawings do not constitute a proportion limitation. In order to more clearly explain that embodiments of the disclosure or technical solutions in the conventional technique, the drawings required for use in the embodiments will be briefly described below, and it will be apparent that the drawings described below are only some of the embodiments of the disclosure, from which other drawings may be obtained without creative effort by a person of ordinary skill in the art.

In view of the above, solar cells have relatively poor photoelectric conversion efficiency in related technologies.

The analysis found that one of reasons for poor photoelectric conversion efficiency of the solar cells in the related technologies is that: in conventional solar cells, due to refining limitation of monocrystalline silicon process for preparing a substrate, only round monocrystalline silicon rods can be made at present, and after the silicon rod is obtained, the silicon rod is sliced. That is, the silicon rod is cut into a monocrystalline silicon wafer (after an area of the monocrystalline silicon wafer is obtained by calculating, an illumination area can be maximized in one unit, a silicon rod material can be saved to the maximum extent, and production of solar cells and components is convenient). A chamfer is generally provided at a junction of a respective first edge and a corresponding second edge of the substrate to reduce external stress of the silicon wafer and avoid micro-damage to corners of the silicon wafer. In addition, to ensure that welding strips (welding belts) do not exceed the chamfers of the solar cell during welding, there is a need to reserve a certain distance between the welding joint and the chamfer of the solar cell, which may make a carrier transmission path in a chamfer region too long and lead to an increased transport loss. Furthermore, if the welding joint or the welding strip is close to an edge of the solar cell, the solar cell may crack during subsequent lamination, which may affect the performance of the solar cell.

Embodiments of the disclosure provide a solar cell. The solar cell includes a substrate having first edges and second edges, where the first edges include two opposite edges of the substrate along a second direction and the second edges include two opposite edges of the substrate along a first direction; a passivation layer disposed on the substrate; a plurality of secondary electrodes arranged at intervals along the second direction on the substrate, where each of the plurality of secondary electrodes extends along the first direction, and penetrates through the passivation layer to be in contact with the substrate; and at least one main electrode located on a surface of the passivation layer, where each of the at least one main electrode includes two connection pads respectively close to the second edges; a connection wire, where each port of ports of the connection wire near a corresponding second edge is closed, and a surface of a portion of the connection wire other than the ports is in contact with each connection pad. A first cross-sectional area of a part of the connection wire between a respective connection pad and a second edge adjacent to the respective connection pad is larger than a second cross-sectional area of another part of the connection wire between the two connection pads.

In some embodiments, a difference between the first cross-sectional area and the second cross-sectional area is proportional to a spacing between the respective connection pad and the second edge adjacent to the respective connection pad.

In some embodiments, a first width of the part of the connection wire between the respective connection pad and the second edge adjacent to the respective connection pad is larger than a second width of the another part of the connection wire between the two connection pads.

In some embodiments, each of the at least one main electrode further includes at least one second connection pad, and the at least one second connection pad is located between the two connection pads. The connection wire is in contact with each second connection pad. For a same main electrode, a third cross-sectional area of a part of the connection wire between two adjacent second connection pads is a smallest cross-sectional area.

In some embodiments, a fourth cross-sectional area of a part of the connection wire between the respective connection pad and a second connection pad adjacent to the respective connection pad is larger than or equal to the third cross-sectional area.

In some embodiments, an area of each of the two connection pads is larger than an area of any of the at least one second connection pad.

In some embodiments, the at least one main electrode includes two first main electrodes and at least one second main electrode. Each of the two first main electrodes is close to a corresponding first edge, and the at least one second main electrode is disposed between the two first main electrodes. The at least one second main electrode is located on the surface of the passivation layer.

In some embodiments, each of the two first main electrodes includes two first sub-connection pads respectively close to the second edges, and a first connection wire. Each port of ports of the first connection wire near the corresponding second edge is closed, and a surface of a portion of the first connection wire other than the ports is in contact with each of the two first sub-connection pads. A fifth cross-sectional area of a part of the first connection wire between a respective first sub-connection pad and a second edge adjacent to the respective first sub-connection pad is larger than a sixth cross-sectional area of another part of the first connection wire between the two first sub-connection pads.

In some embodiments, each of the at least one second main electrode includes a second connection wire. The second connection wire is closed at each port of ports respectively close to the second edges. A cross-sectional area of the first connection wire is larger than or equal to a cross-sectional area of the second connection wire.

In some embodiments, each of the at least one second main electrode further includes second sub-connection pads, where the second sub-connection pads are respectively close to the second edges. The second sub-connection pads are in contact with the second connection wire. In the second direction, a first distance between the respective first sub-connection pad and the second edge adjacent to the respective first sub-connection pad is greater than a second distance between a respective second sub-connection pad and a second edge adjacent to the respective second sub-connection pad.

In some embodiments, a chamfer is provided at a junction of a respective first edge and a corresponding second edge, each of the two first main electrodes is adjacent to a corresponding pair of chamfers, and in the second direction, each of the two first sub-connection pads is located in an edge region outside a corresponding chamfer along the second direction.

In some embodiments, the solar cell is a back contact cell, and the plurality of secondary electrodes include first electrodes and second electrodes alternatively arranged along the second direction. The at least one main electrode includes first grid line structures and second grid line structures alternatively arranged. Each of the first grid line structures is electrically connected with the first electrodes, and each of the second grid line structures is electrically connected with the second electrodes.

In some embodiments, the first grid line structures and the second grid line structures are misaligned in the first direction.

According to the solar cell provided in embodiments of the disclosure, each main electrode includes two connection pads and the connection wire. By arranging the relatively thin connection wire, an effective light shielding area can be reduced, and the resistance loss can be reduced, thereby improving a module total power. In addition, since connection wires forming the main grid lines are densely distributed, more contact points between the main grid lines and the secondary grid lines are obtained, and a current conduction path at cracked and micro-cracked parts of the silicon wafer is more optimized, so the loss caused by micro-cracks is greatly reduced, which is beneficial to improving the output of the production line. In addition, the first cross-sectional area of the part of the connection wire between the respective connection pad and the adjacent second edge is larger than the second cross-sectional area of the another part of the connection wire between the two connection pads, i.e., the width of the part of the connection wire between the connection pad and the adjacent second edge is larger, so that the welding stress of the connection pad can be relieved to form a good contact between the welding strip and the main electrode. Furthermore, the relatively wide connection line can relieve the collection pressure of the connection pad and improve the carrier transmission capacity, and the relatively wide connection line has more transmission area for current collection.

Embodiments of the disclosure further provide a solar cell. The solar cell includes a substrate having first edges and second edges, where the first edges include two opposite edges of the substrate along a second direction and the second edges include two opposite edges of the substrate along a first direction; a passivation layer disposed on the substrate; a plurality of secondary electrodes arranged at intervals along the second direction on the substrate, where each of the plurality of secondary electrodes extends along the first direction, and penetrates through the passivation layer to be in contact with the substrate; two first main electrodes, located on a surface of the passivation layer, where each of the two first main electrodes is close to a corresponding first edge and includes a plurality of first sub-connection pads arranged at intervals along the second direction and a first connection wire, and the first connection wire is in contact with a side of each of at least one of the plurality of first sub-connection pads close to the corresponding first edge; and at least two second main electrodes, where the at least two second main electrodes are located on the surface of the passivation layer, and are located between the two first main electrodes. Each second main electrode of the at least two second main electrodes includes a plurality of second sub-connection pads arranged at intervals along the second direction and a second connection wire. The second connection wire is in contact with at least one of the plurality of second sub-connection pads. A first pitch between a respective first main electrode and a second main electrode adjacent to the respective first main electrode is not equal to a second pitch between two adjacent second main electrodes.

In some embodiments, in the first direction, each secondary electrode of at least one secondary electrode of the plurality of secondary electrodes is in contact with a side of a corresponding first sub-connection pad away from the corresponding first edge.

In some embodiments, a chamfer is provided at a junction of a respective first edge and a corresponding second edge, and each of the two first main electrodes is adjacent to corresponding chamfers. In the second direction, at least one of the first of the plurality of first sub-connection pads and the last of the plurality of first sub-connection pads is located in an edge region outside a corresponding chamfer along the second direction.

In some embodiments, each first connection wire includes a first connection section close to an outside of each of corresponding chamfers in the first direction and a second connection section connected to the first connection section. The first connection section has a cross-sectional area larger than a cross-sectional area of the second connection section.

In some embodiments, in the second direction, a first distance between the first of the plurality of first sub-connection pads and an adjacent second edge is greater than a second distance between the first of the plurality of second sub-connection pads and the adjacent second edge in the second direction.

In some embodiments, in the first direction, for a respective secondary electrode of the plurality of secondary electrodes, a cross-sectional area of a part of the secondary electrode close to the first edge is larger than a cross-sectional area of another part of the secondary electrode away from the first edge.

According to the solar cell provided in embodiments of the disclosure, each first main electrode includes the first sub-connection pads and the first connection wire, and each second main electrode includes the second sub-connection pads and the second connection wire. By arranging the relatively thin first connection wires and the second connection wires, an effective light shielding area and the resistance loss can be reduced, thereby improving the module total power. In addition, since the first connection wires and the second connection wires forming the main grid lines are densely distributed, more contact points between the main grid lines and the secondary grid lines can be obtained, and a current conduction path at the cracked and micro-cracked parts of the silicon wafer is more optimized, so the loss caused by micro-cracks is greatly reduced, which is beneficial to improving the output of the production line. Each first connection wire is in contact with a side of each of the at least one first sub-connection pad close to the first edge, i.e., the first connection wire is closer to the first edge, such that the ability of the first connection wire to collect the current at the first edge is enhanced. In addition, at least one width of the first connection wire is separated between the first sub-connection pad and the first edge, so that the damage caused by poor stress at the edge can be avoided during welding and laminating. In addition, the first pitch between the respective first main electrode and the adjacent second main electrode is not equal to the second pitch between the adjacent second main electrodes. For example, the first pitch is greater than the second pitch, the first main electrode is close to the first edge, and the main electrodes at the edge are sparsely arranged, so that the risk of micro-cracking of the solar cell can be avoided during welding and laminating. Alternatively, the first pitch is smaller than the second pitch, such that the first main electrode and the second main electrode at the edge are densely distributed, and a path of current from the secondary electrode to the main electrode is relatively short, thereby reducing loss and facilitating the ability of the electrode to collect current at the edge.

The embodiments of the disclosure will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that, in various embodiments of the disclosure, many technical details are set forth in order to provide the reader with a better understanding of the disclosure. However, the technical solutions claimed in the disclosure may be realized even without these technical details and various changes and modifications based on the following embodiments.

<FIG> is a schematic structural view illustrating a solar cell according to embodiments of the disclosure. <FIG> is a partial structural view illustrating a solar cell according to embodiments of the disclosure. <FIG> is a schematic structural view illustrating a solar cell according to other embodiments of the disclosure. <FIG> is a schematic structural view illustrating a solar cell according to other embodiments of the disclosure. <FIG> is an enlarged partial view of part A in <FIG>. <FIG> is a schematic structural view illustrating a solar cell according to other embodiments of the disclosure. <FIG> is a schematic structural view illustrating a solar cell according to other embodiments of the disclosure. <FIG> is a schematic structural view illustrating a first main electrode in a solar cell according to embodiments of the disclosure. <FIG> is a schematic structural view illustrating a first main electrode in a solar cell according to other embodiments of the disclosure. <FIG> is a schematic structural view illustrating a first main electrode in a solar cell according to other embodiments of the disclosure. <FIG> is a schematic structural view illustrating a first main electrode in a solar cell according to other embodiments of the disclosure. <FIG> is a schematic structural view illustrating a second main electrode in a solar cell according to embodiments of the disclosure. <FIG> is a schematic structural view illustrating a secondary electrode in a solar cell according to embodiments of the disclosure. <FIG> is a schematic structural view illustrating a solar cell according to other embodiments of the disclosure. <FIG> is a schematic structural view illustrating a solar cell according to other embodiments of the disclosure. <FIG> is a partial structural view of the solar cell according to other embodiments of the disclosure.

According to some embodiments of the disclosure, referring to <FIG>, a solar cell includes a substrate <NUM>, a passivation layer, a plurality of secondary electrodes <NUM>, and at least one main electrode <NUM>. The substrate <NUM> has first edges <NUM> and second edges <NUM>, where the first edges <NUM> include two opposite edges of the substrate <NUM> along a second direction Y and the second edges <NUM> include two opposite edges of the substrate <NUM> along a first direction X. The passivation layer is disposed on the substrate <NUM>. The plurality of secondary electrodes <NUM> are arranged at intervals along the second direction Y on the substrate <NUM>, where each of the plurality of secondary electrodes <NUM> extends along the first direction X, and penetrates through the passivation layer to be in contact with the substrate <NUM>. The at least one main electrode <NUM> is located on a surface of the passivation layer. Each of the at least one main electrode <NUM> includes two connection pads <NUM> respectively close to the second edges <NUM> and a connection wire <NUM>, where each port of ports of the connection wire <NUM> near a corresponding second edge <NUM> is closed, and a surface of a portion of the connection wire <NUM> other than the ports is in contact with each connection pad <NUM>. A first cross-sectional area of a part of the connection wire <NUM> between a respective connection pad <NUM> and a second edge <NUM> adjacent to the respective connection pad <NUM> is larger than a second cross-sectional area of another part of the connection wire <NUM> between the two connection pads <NUM>.

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. The multi-component compound solar cell can specifically be a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenium solar cell, or a perovskite solar cell. The solar cell can also be any one of a passivated emitter and rear cell (PERC) cell, a passivated emitter and rear totally-diffused (PERT) cell, a tunnel oxide passivated contact (TOPCon) cell, and a heterojunction with intrinsic thin layer/heterojunction technology (HIT/HJT) cell. A structure of the solar cell shown in <FIG> is taken as an example for illustration.

The substrate <NUM> is a region that absorbs incident photons and generates photo-generated carriers. In some embodiments, the substrate <NUM> may be a silicon substrate. The silicon substrate may be made of at least one material selected from a group of consisting of single crystal silicon, polysilicon, amorphous silicon, and microcrystalline silicon. In other embodiments, the substrate <NUM> may be made of silicon carbide, organic materials, or multinary compounds. The multinary compounds may include, but are not limited to, materials such as perovskite, gallium arsenide, cadmium telluride, copper indium selenium, and the like. In one example, the substrate <NUM> in embodiments of the disclosure is a monocrystalline silicon substrate.

In some embodiments, a front surface of the substrate <NUM> is a light receiving surface that absorbs incident light and a back surface of the substrate <NUM> is a backlight surface. The substrate <NUM> is doped with a doping element of an N-type or a P-type. The N-type element may be a group V element such as a phosphorus (P) element, a bismuth (Bi) element, an antimony (Sb) element, or an arsenic (As) element. The P-type element may be a group III element, such as a boron (B) element, an aluminum (Al) element, a gallium (Ga) element, or an indium (In) element. For example, when the substrate <NUM> is a P-type substrate <NUM>, the substrate <NUM> is doped with the doping element of the P-type. For another example, when the substrate <NUM> is an N-type substrate, the substrate <NUM> is doped with the doping element of the N-type.

In some embodiments, the substrate <NUM> includes a first surface <NUM> and a second surface <NUM> opposite to the first surface <NUM>. The first surface <NUM> of the substrate <NUM> is provided with an emitter <NUM>, and the emitter <NUM> and the substrate <NUM> are doped with doping elements of different types. A surface of the emitter <NUM> may be a textured surface (i.e., pyramid-textured surface structure), to reduce light reflection of the first surface <NUM> of the substrate <NUM> to the incident light, thereby increasing the absorption and utilization of the light.

The first direction X and the second direction Y may be perpendicular to each other, or there may be an angle of less than <NUM> degrees between the first direction X and the second direction Y, for example, there is an angle of <NUM> degrees, <NUM> degrees, or <NUM> degrees between the first direction X and the second direction Y. In embodiments of the disclosure, the first direction X and the second direction Y are not in a same direction. To facilitate explanation and understanding, in embodiments of the disclosure, the first direction X being perpendicular to the second direction Y is taken as an example for illustration. 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. The disclosure is not limited thereto.

In some embodiments, a chamfer <NUM> is provided at a junction of the first edge <NUM> and the second edge <NUM>. In the second direction Y, each of the two connection pads <NUM> is located in an edge region outside a corresponding chamfer <NUM> along the second direction Y, so that the connection pad <NUM> does not directly face the chamfer <NUM>, which can avoid cracks and micro-cracks at the chamfer <NUM> during welding or laminating. The connection pad <NUM> is close to the chamfer <NUM>, the current collected at the chamfer <NUM> can be collected by the welding strip in a shortest transmission path, thereby reducing the path loss and improving the cell efficiency of the solar cell. Specifically, referring to <FIG>, a distance between a side of the connection pad <NUM> close to the second edge <NUM> and a side of the chamfer <NUM> facing the connection pad <NUM> is relatively small or the side of the connection pad <NUM> close to the second edge <NUM> is adjacent to the side of the chamfer <NUM> facing the connection pad <NUM>, so that the connection pad <NUM> can be considered to be located in the edge region outside the chamfer <NUM> along the second direction Y. A relatively small distance may mean that the distance between the side of the connection pad <NUM> close to the second edge <NUM> and the side of the chamfer <NUM> facing the connection pad <NUM> is smaller than a grid pitch between the adjacent secondary electrodes <NUM>.

In some embodiments, along the second direction Y, the distance between an end of the connection pad <NUM> close to the second edge <NUM> and an edge of the chamfer <NUM> facing the connection pad <NUM> along the second direction Y is less than or equal to the grid pitch between the adjacent secondary electrodes <NUM>, which further illustrates that the current collected at the chamfer <NUM> can be collected by the welding strip in the shortest transmission path, thereby reducing path loss and improving the cell efficiency of the solar cell.

In some embodiments, the passivation layer may be a monolayer structure or a laminated structure. The passivation layer may be made from at least one material selected from a group of consisting of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide. The passivation layer may include a first passivation layer <NUM> and a second passivation layer <NUM>. The first passivation layer <NUM> is located on a surface of the emitter <NUM> away from the substrate <NUM>. The first passivation layer <NUM> may be regarded as a front passivation layer. The second passivation layer <NUM> is located on the second surface <NUM> of the substrate <NUM>, and the second passivation layer <NUM> may be regarded as a rear passivation layer.

In some embodiments, the secondary electrodes <NUM> are grid lines of the solar cell for collecting and converging the current of the solar cell. The secondary electrodes <NUM> may be sintered from a burn-through paste. The material of the secondary electrode <NUM> may be one or more of aluminum, silver, gold, nickel, molybdenum, or copper. In some cases, the secondary electrode <NUM> refers to a fine grid line or a finger grid line, to be distinguished from a main grid line or a bus bar. The secondary electrodes <NUM> include first electrodes <NUM> and second electrodes <NUM>. The first electrodes <NUM> penetrate through the first passivation layer <NUM> to be in contact with the emitter <NUM>. The first electrodes <NUM> are regarded as upper electrodes or front electrodes. The second electrodes <NUM> penetrate through the second passivation layer <NUM> to be in contact with the second surface <NUM> of the substrate <NUM>. The second electrodes <NUM> are regarded as lower electrodes or back electrodes.

In some embodiments, the main electrode <NUM> (i.e., the first main electrode <NUM> and the second main electrode <NUM> mentioned below) is regarded as the main grid line of the solar cell. The main grid line here is not the main grid line in the traditional sense. Instead, the main grid line is a bridge connecting the secondary electrodes <NUM> through the connection wire <NUM> (for example, the first connection wire <NUM> mentioned below), and is connected with welding strips (for connecting solar cells) through the connection pads <NUM> to collect current, so that the relatively thin connection wire <NUM> (e.g., the first connection wire <NUM> and the second connection wire <NUM> mentioned below) can be arranged, to reduce the effective light shielding area, reduce resistance loss, and increase the total power of the assembly. The main electrodes <NUM> can be arranged densely to shorten the path of current passing through the fine grid line, thereby improving the photoelectric conversion efficiency of the solar cell. The thin connection line <NUM> (e.g., the first connection line <NUM> mentioned below) and the connection pad <NUM> (e.g., the first sub-connection pad <NUM> mentioned below) can also avoid the risk of cracks and micro-cracks at the silicon wafer. Therefore, the main electrodes <NUM> are provided at the edge of the solar cell having the risk of cracking and micro-cracking, such that the current collection capability at the edge can be improved, and the current collection or conduction path is more optimized.

In some embodiments, each connection line <NUM> (e.g., a following first connection line <NUM>) is electrically connected to the plurality of secondary electrodes <NUM> for collecting current from each secondary grid line. The connection line <NUM> is set to be thin, and a width of the connection line <NUM> is in a range of <NUM> to <NUM>. For example, the width of the connection line <NUM> is in a range of <NUM> to <NUM>, such as, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. By setting the width of the connection line <NUM> in this range, the light shielding area can be reduced, the shadow loss of the contact grid line can be reduced, and the current collection capability can be improved.

In some embodiments, the connection wire <NUM> (e.g., a subsequent first connection wire <NUM>) is closed at each port of ports close to the second edge <NUM>, which is different from a conventional harpoon connection wire. That is, in embodiments of the disclosure, the connection wire <NUM> has only one connection wire connected with each connection pad <NUM> (for example, the following first sub-connection pad <NUM>). Although the harpoon connection wire can increase the contact points and transmission paths between the main electrodes and the secondary electrodes, the conventional thinner connection wire may cause greater resistance damage of the main electrodes and affect the cell efficiency. Compared with the harpoon connection wire composed of at least two connection wires, only one connection wire is provided, which may reduce the slurry cost and does not affect the alignment of subsequent welding strips. Each port of the connection line <NUM> near the second edge <NUM> is not in contact with the connection pad <NUM> and the connection pad <NUM> is in contact with a region outside the ports of the connection line <NUM>. In this way, when a chamfer <NUM> is provided at each corner of the substrate <NUM>, the connection pad <NUM> is not located in a region where the chamfer <NUM> directly faces, and the connection line <NUM> may be located in the region where the chamfer <NUM> directly faces, thereby collecting the current at the chamfer <NUM>, reducing the carrier transport path in the region of the chamfer <NUM> to reduce the transport loss, and also avoiding the risk of damage due to the arrangement of the connection pad <NUM> at the chamfer <NUM>.

The cross-sectional area refers to a product of a width and a height. To avoid a risk that the solar cell may be cracked or micro-cracked due to different forces in different parts of the solar cell during being connected with the welding strips or lamination, a height of the connection wire <NUM> is set to be the same everywhere. Therefore, the first cross-sectional area being larger than the second cross-sectional area may be referred to that a first width of the part of the connection wire <NUM> between the connection pad <NUM> and the second edge <NUM> is larger than a second width of the another part of the connection wire <NUM> between the two adjacent connection pads <NUM>.

In other embodiments, to avoid the risk of cracking of the part of the connection wire <NUM> close to the edge, it is possible to set a height of the part of the connection wire <NUM> (e.g., a first sub-connection wire <NUM>) between the connection pad <NUM> and the second edge <NUM> to be slightly lower than a height of the another part of the connection wire <NUM> (e.g., a second sub-connection wire <NUM> and a third sub-connection wire <NUM>) between the two adjacent connection pads <NUM>. In this way, the first width of the part of the connection wire <NUM> between the connection pad <NUM> and the second edge <NUM> is also greater than the second width of the another part of the connection wire <NUM> between the two adjacent connection pads <NUM>. The first sub-connection wire <NUM> is relatively wider, which can relieve the welding stress of the connection pads <NUM>, so as to form a good contact between the welding strip and the main electrode <NUM>. In addition, the relatively wider first sub-connection wire <NUM> can relieve the collection pressure of the connection pads <NUM> and improve the carrier transmission capacity, and the relatively wider first sub-connection line <NUM> has a relatively larger transmission area for collecting current.

In some embodiments, a difference between the first cross-sectional area and the second cross-sectional area is proportional to a spacing S between the connection pad <NUM> and the adjacent second edge <NUM>. When the spacing S between the connection pad <NUM> and the adjacent second edge <NUM> is relatively large, the first cross-sectional area is also large, that is, the first width is relatively large, so that the transmission area for the current collected is also large, thereby relieving the collection pressure and improving the performance of the solar cell. The difference between the first cross-sectional area and the second cross-sectional area can be deemed as a difference between the first width and the second width. The difference between the first width and the second width is less than <NUM>. Further, the difference between the first width and the second width is less than <NUM>. The difference between the first width and the second width may be, in particular, <NUM>, <NUM>, <NUM>, or <NUM>. With aid of this configuration, the difference between the first width and the second width can satisfy that the width of the first sub-connection wire <NUM> is relatively larger, the first sub-connection wire <NUM> has better ability for collecting carrier at the second edge, and the shielding area is appropriate to reduce the optical loss. In addition, the cross-sectional area of the second sub-connection wire <NUM> and the third sub-connection wire <NUM> is appropriate, such that the conductivity is good and the resistance loss is relatively small.

In some embodiments, the first width is in a range of <NUM> to <NUM>. Preferably, the first width is in the range of <NUM> to <NUM>, and specifically, the first width may be <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. As such, the first sub-connection wire <NUM> having the width in this range can reduce the shielding area, reduce the shadow loss of the contact grid lines, and improve the current collection capability.

In some embodiments, the second width is in a range of <NUM> to <NUM>. Preferably, the second width is in the range of <NUM> to <NUM>, and specifically, the second width may be <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. Therefore, the cross-sectional area of the second sub-connection wire <NUM> and the third sub-connection wire <NUM> is appropriate, the conductivity is good, and the resistance loss is relatively small.

In some embodiments, the spacing S between the connection pad <NUM> and the adjacent second edge <NUM> is in a range of <NUM> to <NUM>. Preferably, the spacing S is in the range of <NUM> to <NUM>, for example, the spacing S is <NUM>, <NUM>, <NUM>, or <NUM>. The spacing S between the connection pad <NUM> and the second edge <NUM> is appropriate, so that the carrier at the second edge <NUM> can be collected, and the risk of cracking and breakage caused by welding the welding strip can be avoided.

In some embodiments, the connection pad <NUM> may be deemed as a contact point where the main electrode <NUM> is in contact with the welding strip. The connection pad <NUM> may be in contact with the secondary electrode <NUM>. Alternatively, the connection pad <NUM> may not be in contact with the secondary electrode <NUM>, and may be electrically connected to the secondary electrode <NUM> through the connection line <NUM>.

In some embodiments, the main electrode <NUM> further includes at least one second connection pad <NUM> disposed between the two connection pads <NUM>. The connection wire <NUM> is in contact with each second connection pad <NUM>. For a same main electrode <NUM>, a third cross-sectional area of a part of the connection wire <NUM> (i.e., a third sub-connection wire <NUM>) located between two adjacent second connection pads <NUM> is a smallest cross-sectional area. Alternatively, the connection wire <NUM> includes a first sub-connection wire <NUM> between the second edge and the adjacent connection pad <NUM>, a second sub-connection wire <NUM> between the connection pad <NUM> and the adjacent second connection pad <NUM>, and a third sub-connection wire <NUM> between the adjacent second connection pads <NUM>, where the third sub-connection wire <NUM> has a smallest third cross-sectional area. In one example, a fourth cross-sectional area of the second sub-connection wire <NUM> is equal to the third cross-sectional area, i.e., the first cross-sectional area is larger than the third cross-sectional area and the fourth cross-sectional area. The connection wire <NUM> (e.g., the second sub-connection wire <NUM> and the third sub-connection wire <NUM>) in a middle region is relative thinner, so that the shielding area of the grid line can be reduced. In another example, the fourth cross-sectional area of the second sub-connection wire <NUM> is larger than the third cross-sectional area, so that the first cross-sectional area is a largest cross-sectional area, the fourth cross-sectional area is a second largest cross-sectional area, and the third cross-sectional area is the smallest cross-sectional area. In this way, it is possible to ensure that the shielding area in the middle region of the substrate <NUM> is relatively small, a width of the edge region of the substrate <NUM> is relatively large, and the connection wire <NUM> is in better contact with the secondary electrodes <NUM>, such that the current collection capability may be better.

In some embodiments, an area of each of the two connection pads <NUM> is larger than an area of any of the at least one second connection pad <NUM>. When the area of the connection pad <NUM> at the edge is relatively larger, the connection pad <NUM> can be used as a reference for the alignment of the welding strip, to avoid welding deviation between the welding strip and the main electrode <NUM>. In addition, the relatively larger area of the connection pad <NUM> can also relieve the welding pressure of the welding strip and improve the current collection ability at the edge.

In some embodiments, the main electrode <NUM> is a connection wire composed of a plurality of sections of sub-connection wires, and a width of the first sub-connection wire <NUM> is greater than a width of the second sub-connection wire <NUM> and a width of the third sub-connection wire <NUM>. Compared with only one connection wire whose width gradually decreases or increases, the connection wire provided in the disclosure is more beneficial to the alignment of welding strips, reduces the difficulty of the preparation process, and simultaneously reduces the shielding area on the non-edge region of the substrate, such that higher photoelectric conversion efficiency can be achieved.

In some embodiments, referring to <FIG>, the at least one main electrode <NUM> includes two first main electrodes <NUM> and at least one second main electrode <NUM>. The first main electrodes <NUM> are disposed on the surface of the passivation layer, and each first main electrode <NUM> is close to a corresponding first edge <NUM>. The at least one second main electrode <NUM> is located between the two first main electrodes <NUM>, and is disposed on the surface of the passivation layer.

In some embodiments as shown in <FIG>, each first main electrode <NUM> includes two first sub-connection pads <NUM> (or two first sub-connection disks <NUM> described below) respectively close to the second edges <NUM>, and a first connection wire <NUM>. The first connection wire <NUM> is closed at each port of ports respectively close to the second edge <NUM>, and a surface of a portion of the first connection wire <NUM> other than the ports is in contact with each of the two first sub-connection pads <NUM>. A fifth cross-sectional area of a part of the first connection wire <NUM> between the first sub-connection pad <NUM> and the adjacent second edge <NUM> is larger than a sixth cross-sectional area of another part of the first connection wire <NUM> between the two first sub-connection pads <NUM>.

In some embodiments, the first main electrode <NUM> further includes at least one third sub-connection pad <NUM> (or at least one second sub-connection disk <NUM> described below). The at least one third sub-connection pad <NUM> is disposed between the two first sub-connection pads <NUM>. The first connection wire <NUM> is in contact with each third sub-connection pad <NUM>. For a same first main electrode <NUM>, a seventh cross-sectional area of a part of the first connection wire <NUM> located between two adjacent third sub-connection pads <NUM> is a smallest cross-sectional area. Alternatively, the first connection wire <NUM> includes a first connection section <NUM> disposed between the first sub-connection pad <NUM> and the adjacent second edge <NUM>, a second connection section <NUM> disposed between the first sub-connection pad <NUM> and the adjacent third sub-connection pad <NUM>, and a third connection section <NUM> disposed between adjacent third sub-connection pads <NUM>, the third connection section <NUM> has a smallest seventh cross-sectional area. In one example, referring to <FIG>, an eighth cross-sectional area of the second connection section <NUM> is equal to the seventh cross-sectional area (i.e., the fifth cross-sectional area is larger than the seventh cross-sectional area and the eighth cross-sectional area). The first connection wire <NUM> in the middle region is thinner, which can reduce the shielding area of the grid line. In another example, referring to <FIG>, the eighth cross-sectional area of the second connection section <NUM> is larger than the seventh cross-sectional area. That is, the fifth cross-sectional area is the largest cross-sectional area, the eighth cross-sectional area is a second largest cross-sectional area, and the seventh cross-sectional area is a smallest largest cross-sectional area. With aid of this configuration, it is possible to ensure that the shielding area in the middle region of the substrate <NUM> is small, the width of the edge region is relatively large, and a good contact between the first connection wire <NUM> and the secondary electrodes <NUM> may be obtained, such that a better current collection ability may be achieved.

In some embodiments, as illustrated in <FIG>, each first main electrode <NUM> includes a plurality of first sub-connection pads <NUM> arranged at intervals along the second direction Y and a first connection wire <NUM>. The first connection wire <NUM> is in contact with a side of each of at least one of the first sub-connection pads <NUM> near the first edge <NUM>. The first main electrode <NUM> is adjacent to corresponding chamfers <NUM>. In the second direction Y, the first of the first sub-connection pads <NUM> and/or the last of the first sub-connection pads <NUM> are located in an edge region outside the chamfers <NUM> along the second direction Y, so that at least one of the first of the first sub-connection pads 131and the last of the first sub-connection pads <NUM> is not located in a region directly facing the chamfer <NUM>, which can avoid cracks and microcracks at the chamfer <NUM> during welding or laminating. When the first sub-connection pad <NUM> is close to the chamfer <NUM>, the current collected at the chamfer <NUM> can be collected by the welding strip in a shortest transmission path, thereby reducing the path loss and improving the cell efficiency of the solar cell. Specifically, referring to <FIG>, a distance between a side of the first of the first sub-connection pads <NUM> near the second edge <NUM> and a side of the chamfer <NUM> facing the first sub-connection pad is relatively small or the side of the first of the first sub-connection pads <NUM> near the second edge <NUM> is adjacent to the side of the chamfer <NUM> facing the first sub-connection pad, so that the first sub-connection pad <NUM> can be considered to be located in the edge region outside the chamfer <NUM> in the second direction Y. A relatively small distance may mean that the distance between the side of the first of the first sub-connection pads <NUM> near the second edge <NUM> and the side of the chamfer <NUM> facing the first sub-connection pad is smaller than the grid pitch between the adjacent secondary electrodes <NUM>.

In some embodiments, along the second direction Y, a distance between an end of the first sub-connection pad <NUM> close to the second edge and an edge of the chamfer <NUM> facing the first sub-connection pad <NUM> along the second direction Y is less than or equal to the grid pitch between the adjacent secondary electrodes <NUM>, which further illustrates that the current collected at the chamfer <NUM> can be collected by the welding strip in the shortest transmission path, thereby reducing the path loss and improving the battery efficiency of the solar cell.

In some embodiments, as illustrated in <FIG>, each second main electrode <NUM> includes a second connection wire <NUM>. The second connection wire <NUM> is closed at each port of ports respectively close to the second edges <NUM>. A cross-sectional area of the first connection wire <NUM> is larger than or equal to a cross-sectional area of the second connection wire <NUM>. For a second main electrode <NUM> in the non-edge region, the relatively thin second connection wire <NUM> ensures that a grid line shielding area of the second main electrode <NUM> is relatively smaller. For the first main electrode <NUM> in the edge region, the relatively wide first connection wire <NUM> increase a cross-sectional area of electrical contact between the first connection wire <NUM> and each secondary electrode <NUM>, reduces the resistance of the first connection wire <NUM>, and improves the current collection and transmission capability of the first connection wire <NUM> adjacent to the edge of the substrate <NUM> compared with the thinner second connection wire <NUM>, thereby improving the edge current collection capability and photoelectric conversion efficiency of the whole solar cell.

In some embodiments, a first pitch m between the first main electrode <NUM> and the adjacent second main electrode <NUM> is not equal to a second pitch n between the adjacent second main electrodes <NUM>. In one example, the first pitch m is larger than the second pitch n, i.e., the first main electrode <NUM> is close to the first edge <NUM>. The main electrodes at the edges are sparsely arranged, so that the risk of micro-cracking and the like of the solar cell can be avoided during welding and laminating. A ratio P of the first distance m to the second pitch n ranges from <NUM> to <NUM> (i.e., <NUM> ≥ P > <NUM>), and further, <NUM> ≥ P > <NUM>, <NUM> ≥ P > <NUM>, <NUM> ≥ P > <NUM>, or <NUM> ≥ P > <NUM>. In another example, the first pitch m is less than the second pitch n, which may ensure that the first main electrodes <NUM> at the edges and the second main electrodes <NUM> are densely arranged and a path of current from the secondary electrode <NUM> to the main electrode is shorter, thereby reducing loss and facilitating the ability of the electrodes to collect current at the edges. In this case, the ratio P of the first distance m to the second pitch n ranges from <NUM> to <NUM> (i.e., <NUM> > P ≥ <NUM>. <NUM>), and further, <NUM> > P ≥ <NUM>. <NUM>, <NUM> ≥ P ≥ <NUM>, <NUM> ≥ P ≥ <NUM>, or <NUM> ≥ P ≥ <NUM>.

In some embodiments, the first connection wire <NUM> and the second connection wire <NUM> are made of same materials, i.e., the first connection wire <NUM> and the second connection wire <NUM> are made under a same fabrication process.

In some embodiments, the second main electrode <NUM> further includes a plurality of second sub-connection pads <NUM> arranged at intervals in the second direction Y. The first of the plurality of second sub-connection pads <NUM> and the last of the plurality of second sub-connection pads <NUM> are respectively adjacent to the second edges <NUM>, and each second sub-connection pad <NUM> is in contact with the second connection line <NUM> (i.e., the second connection line <NUM> is in contact with at least one of the second sub-connection pads <NUM>). In the second direction Y, a first distance between the first of the first sub-connection pads <NUM> and the adjacent second edge <NUM> is greater than a second distance between the first of the second sub-connection pads <NUM> and the second edge <NUM>. Since the chamfer <NUM> is provided at the junction the first edge <NUM> and the second edge <NUM> of the substrate <NUM>, the first sub-connection pad <NUM> is relatively far away from the second edge <NUM>, and the second sub-connection pad <NUM> is closer to the second edge <NUM> than the first sub-connection pad <NUM>, such that the current transmission path at the second edge <NUM> can be shortened, and the current collection ability of the second edge <NUM> can be improved.

In some embodiments, the first sub-connection pad <NUM> may be regarded as a contact point where the first main electrode <NUM> is in contact with the welding strip. The first sub-connection pad <NUM> may be in contact with the secondary electrode. Alternatively, the first sub-connection pad <NUM> may not be in contact with the secondary electrode and may be electrically connected to the secondary electrode through the first connection line <NUM>. Similarly, the second sub-connection pad <NUM> is a contact point where the second main electrode <NUM> is in contact with the welding strip.

In some embodiments, an area of each first sub-connection pad <NUM> is larger than an area of any of the second sub-connection pads <NUM>. When the area of each first sub-connection pad <NUM> located at the edge is larger, the first sub-connection pad <NUM> can be used as a reference for the alignment of the welding strip, to avoid welding deviation between the welding strip and the first main electrode <NUM>. In addition, the relatively larger area of the first sub-connection pad <NUM> can also relieve the pressure of the welding strip and improve the current collection ability at the edge, and the relatively smaller area of the second sub-connection pad <NUM> can reduce the shielding area.

In some embodiments, with reference to <FIG> and <FIG>, the first connection wire <NUM> is in contact with a side of each of at least one of the first sub-connection pads <NUM> close to the first edge <NUM>. The first connection wire <NUM> is closer to the first edge <NUM>, and the ability of the first connection wire <NUM> to collect the current at the first edge <NUM> is enhanced. In addition, at least one width of the first connection wire <NUM> is separated between the first sub-connection pad <NUM> and the first edge <NUM>, so that the breakage caused by poor stress at the edge can be avoided during welding and laminating. When the first sub-connection pad <NUM> is in contact with the secondary electrode, the secondary electrode is in contact with a side of the first sub-connection pad <NUM> away from the first edge <NUM>, so that the current collected by the secondary electrode can be directly collected by the first sub-connection pad and converged on the welding strip, thereby reducing the current transmission path.

In some embodiments, referring to <FIG>, the first connection wire <NUM> includes a first connection section <NUM> close to an outside of the chamfer <NUM> in the first direction X and a second connection section <NUM> connected to the first connection section <NUM>. The first connection section <NUM> has a cross-sectional area larger than a cross-sectional area of the second connection section <NUM>. Alternatively, an eleventh cross-sectional area of a part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the adjacent second edge <NUM> is larger than a twelfth cross-sectional area of another part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the last of the first sub-connection pads <NUM>. A width of the part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the adjacent second edge <NUM> is larger, so that the welding stress of the first sub-connection pad <NUM> can be relieved to form a good contact between the welding strip and the first main electrode <NUM>. In addition, the wider first connection wire <NUM> can relieve the pressure of the current collection of the first sub-connection pad <NUM> and improve the carrier transmission capacity, and the wider first connection wire <NUM> has a larger transmission area for current collection.

It can be understood that the first connection section <NUM> refers to the part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the adjacent second edge <NUM>, and the second connection section <NUM> refers to the another part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the last of the first sub-connection pads <NUM>.

To avoid cracking or micro-cracking of the solar cell due to different forces in different parts of the solar cell during being connected with welding strips or lamination, a height of the first connection wire <NUM> is set to be the same everywhere. Therefore, the eleventh cross-sectional area being larger than the twelfth cross-sectional area may be considered that a third width of the part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the adjacent second edge <NUM> is larger than a fourth width of the another part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the last of the first sub-connection pads <NUM>.

In other embodiments, to avoid cracking of the part of the first connection wire <NUM> close to the edge, it is possible to set a height of the part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the adjacent second edge <NUM> to be slightly lower than a height of the another part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the last of the first sub-connection pads <NUM>. In this way, the third width of the part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the adjacent second edge <NUM> is greater than the fourth width of the another part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the last of the first sub-connection pads <NUM>. The part of the first connection wire <NUM> between the first of the first sub-connection pads <NUM> and the adjacent second edge <NUM> is wider, which can relieve the welding stress of the first sub-connection pad <NUM>, so as to form a good contact between the welding strip and the first main electrode <NUM>. In addition, the wider first connection wire <NUM> can relieve the pressure of the current collection of the first sub-connection pad <NUM> and improve the carrier transmission capacity, and the wider first connection wire <NUM> has a larger transmission area for current collection.

In some embodiments, a difference between the eleventh cross-sectional area and the twelfth cross-sectional area is proportional to a spacing S between the first of the first sub-connection pads <NUM> and the adjacent second edge <NUM>. When the spacing S between the first of the first sub-connection pads <NUM> and the adjacent second edge <NUM> is large, the eleventh cross-sectional area is also large, that is, the third width is also large, so that the transmission area for the current collection is also large, thereby relieving the collection pressure and improving the cell performance. The difference between the eleventh cross-sectional area and the twelfth cross-sectional area can be regarded as a difference between the third width and the fourth width. The difference between the third width and the fourth width is less than <NUM>. Further, the difference between the third width and the fourth width is less than <NUM>. The difference between the third width and the fourth width may be, in particular, <NUM>, <NUM>, <NUM>, or <NUM>. With aid of this configuration, the difference between the third width and the fourth width can satisfy that the width of the first connection section <NUM> is larger, the first connection section <NUM> has better ability for collecting carrier at the second edge, and the shielding area is appropriate to reduce the optical loss. In addition, the cross-sectional area of the second connection section <NUM> is appropriate, such that the conductivity is good and the resistance loss is small.

In some embodiments, the third width is in a range of <NUM> to <NUM>. Preferably, the third width is in the range of <NUM> to <NUM>, and specifically, the third width is <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. As such, the first connection section <NUM> having the width in this range can reduce the shielding area, reduce the shadow loss of the contact grid lines, and improve the current collection capability. The fourth width is in a range of <NUM> to <NUM>. Preferably, the fourth width is in the range of <NUM> to <NUM>, and specifically, the fourth width is <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. Therefore, the cross-sectional area of the second connection section <NUM> is appropriate, the conductivity is good, and the resistance loss is small. The spacing S between the first sub-connection pad <NUM> and the adjacent second edge <NUM> ranges from <NUM> to <NUM>, preferably, from <NUM> to <NUM>. The spacing S may be <NUM>, <NUM>, <NUM>, or <NUM>. The spacing between the first sub-connection pad <NUM> and the second edge <NUM> is appropriate, so that the carrier at the second edge <NUM> can be collected, and the risk of cracking and breakage caused by welding the welding strip can be avoided.

In some embodiments, referring to <FIG>, the plurality of first sub-connection pads <NUM> include two first sub-connection disks <NUM> and at least one second sub-connection disk <NUM> disposed between the two first sub-connection disks <NUM>. There are one or more second sub-connection disks <NUM>. A seventh cross-sectional area of a part of the first connection wire <NUM> (third connection section <NUM>) located between two adjacent second sub-connection disks <NUM> is a smallest cross-sectional area. In one example, referring to <FIG>, an eighth cross-sectional area of a part of the first connection wire <NUM> (second connection section <NUM>) located between the first sub-connection disk <NUM> and the adjacent second sub-connection disk <NUM> is equal to the seventh cross-sectional area. That is, the first connection wire <NUM> in the middle region is thinner, which can reduce the shielding area of the grid line. In another example, the eighth cross-sectional area of the part of the first connection wire <NUM> (second connection section <NUM>) between the first sub-connection disk <NUM> and the adjacent second sub-connection disk <NUM> is larger than the seventh cross-sectional area. In this way, the eleventh cross-sectional area is the largest cross-sectional area, the eighth cross-sectional area is a second cross-sectional area, and the seventh cross-sectional area is the smallest cross-sectional area. With aid of this configuration, it is possible to ensure that the shielding area in the middle region of the substrate <NUM> is small, the width of the edge region is relatively large, and a good contact between the first connection wire <NUM> and the secondary electrodes <NUM> may be obtained, such that a better current collection ability may be achieved.

In some embodiments, an area of the first sub-connection disk <NUM> is larger than an area of the second sub-connection disk <NUM>. When the area of the first sub-connection disk <NUM> located at the edge is large, the first sub-connection disk <NUM> can be used as a reference for the alignment of the welding strip, to avoid welding deviation between the welding strip and the first main electrode <NUM>. In addition, the relatively larger area of the first sub-connection disk <NUM> can also relieve the pressure of the welding strip and improve the current collection ability at the edge.

In some embodiments, the second connection wire <NUM> is closed at each port of ports respectively close to the second edges <NUM>. The cross-sectional area of the first connection wire <NUM> is larger than or equal to the cross-sectional area of the second connection wire <NUM>. For the second main electrode <NUM> in the non-edge region, the relatively thin second connection wire <NUM> ensures that a grid line shielding area of the second main electrode <NUM> is relatively smaller. For the first main electrode <NUM> in the edge region, a relatively wide first connection wire <NUM> increase a cross-sectional area of electrical contact between the first connection wire <NUM> and each secondary electrode <NUM>, reduces the resistance of the first connection wire <NUM>, and improves the current collection and transmission capability of the first connection wire <NUM> adjacent to the edge of the substrate <NUM> compared with the thinner second connection wire <NUM>, thereby improving the edge current collection capability and photoelectric conversion efficiency of the whole solar cell.

In some embodiments, referring to <FIG> and <FIG>, the second connection wire <NUM> is closed at each port of ports respectively close to the second edges <NUM> and a surface of a portion of the second connection wire <NUM> other than the ports is in contact with the second sub-connection pad <NUM>. Referring to <FIG>, <FIG>, and <FIG>, a ninth cross-sectional area of a part of the second connection wire <NUM> (i.e., a fourth connection section <NUM>) between the second sub-connection pad <NUM> and the adjacent second edge <NUM> is larger than a tenth cross-sectional area of another part of the second connection wire <NUM> (i.e., a fifth connection section <NUM>) between two adjacent second sub-connection pads <NUM>. A technical concept and the technical effect achieved of the ninth cross-sectional area being larger than the tenth cross-sectional area are the same as or similar to the technical concept and the technical effect achieved of the first cross-sectional area being larger than the second cross-sectional area, which are not repeated herein.

In some embodiments, referring to <FIG> and <FIG>, in the first direction X, a cross-sectional area of a part of the secondary electrode <NUM> near the first edge <NUM> is larger than a cross-sectional area of another part of the secondary electrode <NUM> away from the first edge <NUM>, to enhance the current collection and transmission capability of the secondary electrodes <NUM> at the first edge <NUM>.

In some embodiments, the solar cell is a multi-busbar (MBB) cell.

In some embodiments, referring to <FIG> and <FIG>, the connection wire is in contact with a side of each of at least one sub-connection pad adjacent to the first edge <NUM>. The connection wire is close to the first edge <NUM>, and the ability of the connection wire to collect the current at the first edge <NUM> is enhanced. In addition, at least one width of the first connection wire is separated between the sub-connection pad and the first edge <NUM>, so that the breakage caused by poor stress at the edge can be avoided during welding and laminating. The sub-electrode <NUM> is in contact with a side of the sub-connection pad away from the first edge <NUM>, so that the current collected by the secondary electrode can be collected directly by the sub-connection pad and converged onto the welding strip, thereby reducing the current transmission path.

In some embodiments, the solar cell is a back contact cell, such as an interdigitated back contact (IBC) cell. Referring to <FIG>, the back contact cell includes a substrate <NUM>, a third passivation layer <NUM> on a first surface <NUM> of the substrate <NUM>; a first doped region <NUM> and a second doped region <NUM> located on a second surface <NUM> of the substrate <NUM>; a fourth passivation layer <NUM> disposed on a surface of the first doped region <NUM> and the second doped region <NUM>; first electrode s <NUM> which penetrate through the fourth passivation layer <NUM> to be connected to the first doped region <NUM>; and second electrodes <NUM> which penetrate through the fourth passivation layer <NUM> to be connected to the second doped region <NUM>. In other embodiments, the back contact cell includes a substrate; a third passivation layer on a first surface of the substrate; a first doped region provided on a second surface of the substrate, where the first doped region may have the same conductivity type as the substrate or may have a different conductivity type from the substrate; a tunneling oxide layer and a doped polysilicon layer, where the tunneling oxide layer and the doped polysilicon layer are located on the second surface of the substrate; a fourth passivation layer located a surface of the first doping region and the doped polysilicon layer; first electrodes which penetrate through the fourth passivation layer to be connected with the doped polysilicon layer; and second electrodes which penetrate the fourth passivation layer to be connected with the first doped region. In still other embodiments, the back contact cell includes a substrate, a third passivation layer on a first surface of the substrate; a tunneling oxide layer, a first doped polysilicon layer, and a second doped polysilicon layer disposed over the second surface of the substrate; a fourth passivation layer disposed on a surface of the first doped polysilicon layer, the second doped polysilicon layer, and the substrate; first electrodes which penetrate through the fourth passivation layer to be connected with the first doped polysilicon layer; and second electrodes which penetrate through the fourth passivation layer to be connected with the second doped polysilicon layer. It can be understood that the first surface <NUM> is a front surface of the silicon substrate, the second surface <NUM> is a back surface of the silicon substrate, the first doped region is one of the N-type doped region and the P-type doped region, and the second doped region is the other of the N-type doped region and the P-type doped region.

It can be understood that the "back contact cell" means that all the positive electrodes and the negative electrodes are in contact with a structure on the back surface of the substrate <NUM> for current collection, and there is no positive electrode and negative electrode disposed on the front surface of the substrate <NUM>.

In some embodiments, the back contact cell includes a substrate <NUM>, a passivation layer, a plurality of secondary electrodes <NUM>, and at least one main electrode <NUM>. The substrate <NUM> has first edges <NUM> and second edges <NUM>, where the first edges <NUM> include two opposite edges of the substrate <NUM> along a second direction Y and the second edges <NUM> include two opposite edges of the substrate <NUM> along a first direction X. The passivation layer is disposed on the substrate <NUM>. The plurality of secondary electrodes <NUM> are arranged at intervals along the second direction Y on the substrate <NUM>, where each of the plurality of secondary electrodes <NUM> extends along the first direction X, and penetrates through the passivation layer to be in contact with the substrate <NUM>. The at least one main electrode <NUM> is located on a surface of the passivation layer. Each of the at least one main electrode <NUM> includes two connection pads <NUM> respectively close to the second edges <NUM> and a connection wire <NUM>, where each port of ports of the connection wire <NUM> near a corresponding second edge <NUM> is closed, and a surface of a portion of the connection wire <NUM> other than the ports is in contact with each connection pad <NUM>. A first cross-sectional area of a part of the connection wire <NUM> between a respective connection pad <NUM> and a second edge <NUM> adjacent to the respective connection pad <NUM> is larger than a second cross-sectional area of another part of the connection wire <NUM> between the two connection pads <NUM>.

In some embodiments, a difference between the first cross-sectional area and the second cross-sectional area is proportional to a spacing between the connection pad and the adjacent second edge. A first width of a part of the connection wire between the connection pad and the adjacent second edge is larger than a second width of another part of the connection wire between the connection pads.

In some embodiments, the secondary electrodes <NUM> include first electrodes <NUM> and second electrodes <NUM> that are alternatively arranged along the second direction. The first electrode <NUM> is one of a positive electrode and a negative electrode, and the second electrode <NUM> is the other of the positive electrode and the negative electrode. In embodiments of the disclosure, the first electrode <NUM> is taken as a positive electrode and the second electrode <NUM> is taken as a negative electrode for illustration. The secondary electrodes <NUM> include first electrodes <NUM> and second electrodes <NUM> alternatively arranged along the second direction Y.

In some embodiments, referring to <FIG>, the at least one main electrode includes first grid line structures <NUM> and second grid line structures <NUM> alternatively arranged. Each first grid line structure <NUM> is electrically connected to corresponding first electrodes <NUM> and each second grid line structure <NUM> is electrically connected to corresponding second electrodes <NUM>. Specifically, the at least one first main electrode includes a first edge grid line and a second edge grid line. The first edge grid line is electrically connected to the first electrodes <NUM> and the second edge grid line is electrically connected to the second electrodes <NUM>.

In some embodiments, the first grid line structures <NUM> and the second grid line structures <NUM> are misaligned along the first direction X, so that along the second direction Y, a distance between an end of the first grid line structure <NUM> close to the second edge and the adjacent second edge is different from a distance between an end of the second grid line structure <NUM> close to the second edge and the adjacent second edge. In this way, it is possible to reduce the consumption of the conductive silver paste for the solar cell metallization and shorten the distance of current collection in the fine grid-line direction, thereby reducing the fragmentation rate. In addition, at least part of the main grid line may not be exposed to one end of the secondary electrode near the second edge, which is beautiful and ensures the adaptive length of the positive and negative electrodes of the solar cell, and can avoid the risk of short circuit between electrodes with different polarities.

In some embodiments, referring to <FIG>, the second main electrodes include first grid line structures <NUM> and second grid line structures <NUM> alternately arranged. Each first grid line structure <NUM> is electrically connected to corresponding first electrodes <NUM> and each second grid line structure <NUM> is electrically connected to corresponding second electrodes <NUM>. The two first main electrodes include a first edge grid line <NUM> and a second edge grid line <NUM>. The first edge grid line <NUM> is electrically connected to the first electrodes <NUM> and the second edge grid line <NUM> is electrically connected to the second electrodes <NUM>. Specifically, a second main electrode adjacent to the first edge grid line <NUM> having positive polarity is the second grid line structure <NUM>, and a second main electrode adjacent to the second edge grid line <NUM> having negative polarity is the first grid line structure <NUM>.

In some embodiments, the first grid line structures <NUM> and the second grid line structures <NUM> are misaligned along the first direction X, so that along the second direction Y, a distance between an end of the first grid line structure <NUM> close to the second edge and the adjacent second edge is different from a distance between an end of the second grid line structure <NUM> close to the second edge and the adjacent second edge. In this way, it is possible to reduce the consumption of the conductive silver paste for the solar cell metallization and shorten the distance of current collection in the fine grid-line direction, thereby reducing the fragmentation rate. In addition, at least part of the main grid line may not be exposed to one end of the secondary electrode near the second edge, which is beautiful and ensures the adaptive length of the positive and negative electrodes of the solar cell, and can avoid the risk of short circuit between electrodes with different polarities. Similarly, the first edge grid line <NUM> and the second edge grid line <NUM> are arranged in a misaligned manner along the first direction X to avoid the short circuit between different secondary electrodes.

In the solar cell provided in the embodiments of the disclosure, the main electrode <NUM> includes connection pads <NUM> and the connection line <NUM> (for example, the first main electrode <NUM> includes first sub-connection pads <NUM> and the first connection line <NUM>, and the second main electrode <NUM> includes second sub-connection pads <NUM> and the second connection line <NUM>). By providing the thinner connection line <NUM>, effective light shielding areas and resistance loss can be reduced, thereby increasing the total power of the assembly. In addition, since the connection wires <NUM> constituting the main grid lines (e.g., the first connection wires <NUM> and the second connection wires <NUM>) are more densely distributed, more contact points between the main grid lines and the fine grid lines can be obtained, and a path of current conduction at the cracked and micro-cracked parts of the silicon wafer is more optimized, so that the loss caused by micro-cracks is greatly reduced, which is beneficial to improving the output of the production line. The first cross-sectional area of the part of the connection wire <NUM> between the respective connection pad <NUM> and the adjacent second edge <NUM> is larger than the second cross-sectional area of the another part of the connection wire <NUM> between the two adjacent connection pads <NUM>, i.e., the width of the part of the connection wire <NUM> between the second edge <NUM> and the connection pad <NUM> is larger, so that the welding stress of the connection pad <NUM> can be relieved to form a good contact between the welding strip and the main electrode <NUM>. In addition, the wider connection line <NUM> can relieve the collection pressure of the connection pad <NUM> and improve the carrier transmission capacity, and the wider connection line has a larger transmission area for collecting current. Furthermore, each first connection wire <NUM> is in contact with a side of each of the at least one first sub-connection pad <NUM> close to the first edge <NUM>, i.e., the first connection wire <NUM> is closer to the first edge <NUM>, and the ability of the first connection wire <NUM> to collect the current at the first edge <NUM> is enhanced. In addition, at least one width of the first connection wire <NUM> is separated between the first sub-connection pad <NUM> and the first edge <NUM>, so that the breakage caused by poor stress at the edge can be avoided during welding and laminating.

Furthermore, the first pitch m between the first main electrode <NUM> and the adjacent second main electrode <NUM> is not equal to the second pitch n between the adjacent second main electrodes <NUM>. In one example, the first pitch m is larger than the second pitch n, i.e., the first main electrode <NUM> is close to the first edge <NUM>. The main electrodes at the edges are sparsely arranged, so that the risk of micro-cracking and the like of the solar cell can be avoided during welding and laminating. In another example, the first pitch m is less than the second pitch n, which may ensure that the first main electrodes <NUM> at the edges and the second main electrodes <NUM> are densely arranged and a path of current from the secondary electrode <NUM> to the main electrode is shorter, thereby reducing loss and facilitating the ability of the electrodes to collect current at the edges.

<FIG> is a schematic structural view of a photovoltaic module according to embodiments of the disclosure.

Embodiments of the disclosure further provide a photovoltaic module. As illustrated in <FIG>, the photovoltaic module includes one or more cell strings. Each cell string is formed by connecting a plurality of solar cells <NUM>. Each of the plurality of solar cells <NUM> is a solar cell provided in the above embodiments. The photovoltaic module further includes at least one encapsulating layer <NUM> and at least one cover plate <NUM>. Each encapsulating layer <NUM> is configured to cover a surface of each of the at least one cell string. Each cover plate <NUM> is configured to cover a surface of a corresponding encapsulating layer <NUM> of the at least one encapsulating layer <NUM> facing away from the at least one cell string. The solar cells <NUM> are electrically connected in the form of a whole piece or multiple pieces to form a plurality of cell strings, and the plurality of cell strings are electrically connected in series and/or parallel.

In some embodiments, the plurality of solar cells can be electrically connected through a conductive stripe. The at least one encapsulation layer <NUM> includes a first encapsulation layer <NUM> and a second encapsulation layer <NUM>. The first encapsulation layer <NUM> is configured to cover one of the front surface and the back surface of the solar cell <NUM>, and the second encapsulation layer <NUM> is configured to cover the other of the front surface and the back surface of the solar cell <NUM>. Specifically, at least one of the first encapsulation layer <NUM> and the second encapsulation layer <NUM> may be an organic encapsulation adhesive film such as an ethylene-vinyl acetate copolymer (EVA) adhesive film, a polyethylene octene co-elastomer (POE) adhesive film, or a polyethylene terephthalate (PET) adhesive film. In some embodiments, the cover plate <NUM> may be a cover plate with a light-transmitting function, such as a glass cover plate, a plastic cover plate, or the like. Specifically, a surface of the cover plate <NUM> facing the encapsulation layer <NUM> may be an uneven surface, thereby increasing the utilization rate of the incident light. The cover plate <NUM> includes a first cover plate <NUM> and a second cover plate <NUM>. The first cover plate <NUM> faces the first encapsulation layer <NUM> and the second cover plate <NUM> faces the second encapsulation layer <NUM>.

Claim 1:
A solar cell, comprising:
a substrate (<NUM>) having first edges (<NUM>) and second edges (<NUM>), wherein the first edges (<NUM>) comprises two opposite edges of the substrate (<NUM>) along a second direction (Y) and the second edges are comprises two opposite edges of the substrate (<NUM>) along a first direction (X);
a passivation layer disposed on the substrate (<NUM>);
a plurality of secondary electrodes (<NUM>) arranged at intervals along the second direction (Y) on the substrate (<NUM>), wherein each of the plurality of secondary electrodes (<NUM>) extends along the first direction (X), and penetrates through the passivation layer to be in contact with the substrate (<NUM>);
two first main electrodes (<NUM>), disposed on a surface of the passivation layer, wherein each of the two first main electrodes (<NUM>) is close to a corresponding first edge (<NUM>) and comprises a plurality of first sub-connection pads (<NUM>) arranged at intervals along the second direction and a first connection wire (<NUM>), and the first connection wire (<NUM>) is in contact with a side of each of at least one of the plurality of first sub-connection pads (<NUM>) close to the corresponding first edge (<NUM>); and
at least two second main electrodes (<NUM>), where the at least two second main electrodes (<NUM>) are disposed on the surface of the passivation layer, and are disposed between the two first main electrodes (<NUM>), wherein each of the at least two second main electrodes (<NUM>) comprises a plurality of second sub-connection pads (<NUM>) arranged at intervals along the second direction (Y) and a second connection wire (<NUM>), and the second connection wire (<NUM>) is in contact with at least one of the plurality of second sub-connection pads (<NUM>), wherein
a first pitch (m) between a respective first main electrode (<NUM>) and a second main electrode (<NUM>) adjacent to the respective first main electrode (<NUM>) is not equal to a second pitch (n) between adjacent second main electrodes (<NUM>).