CN115377231B

CN115377231B - Solar cell and photovoltaic module

Info

Publication number: CN115377231B
Application number: CN202211298934.9A
Authority: CN
Inventors: 黄世亮; 郭志球; 关迎利
Original assignee: Zhejiang Jinko Solar Co Ltd
Current assignee: Zhejiang Jinko Solar Co Ltd
Priority date: 2022-10-24
Filing date: 2022-10-24
Publication date: 2023-10-24
Anticipated expiration: 2042-10-24
Also published as: CN115377231A; CN117038752A

Abstract

The embodiment of the application relates to the field of photovoltaics, and provides a solar cell and a photovoltaic module, wherein the solar cell comprises: the substrate is provided with a first edge and a second edge, wherein the first edge is the edge of the substrate along the first direction, and the second edge is the edge of the substrate along the second direction; the passivation layer is positioned on the substrate; at least one main electrode, said main electrode is located on the surface of said passivation layer, said main electrode comprises: two connection pads near the second edge; a connecting line, the connecting line being closed near a port of the second edge, a portion of a surface of the connecting line other than the port being in contact with each of the connecting pads; the first cross-sectional area of the connecting line between the connecting pad and the adjacent second edge is greater than the second cross-sectional area of the connecting line between the connecting pads. The solar cell and the photovoltaic module provided by the embodiment of the application can at least improve the photoelectric conversion efficiency of the solar cell.

Description

Solar cell and photovoltaic module

Technical Field

The embodiment of the application relates to the field of photovoltaics, in particular to a solar cell and a photovoltaic module.

Background

The causes affecting the performance of the solar cell (e.g., photoelectric conversion efficiency) include optical losses including reflection losses at the front surface of the cell, shadow losses in contact with the gate line, and non-absorption losses in the long band, etc., as well as electrical losses including losses in the semiconductor surface and in vivo photo-generated carrier recombination, contact resistance of the semiconductor and metal gate line, contact resistance of the metal and semiconductor, etc.

The solar cell is characterized in that the secondary grid and the primary grid are arranged to collect and output current generated by the cell, and the current generated by the cell is transmitted to the component end through the bonding pad arranged on the primary grid. However, the current collection capability of the solar cell in the prior art is weak, so that the improvement of the photoelectric conversion efficiency of the solar cell is affected.

Disclosure of Invention

The embodiment of the application provides a solar cell and a photovoltaic module, which are at least beneficial to improving the photoelectric conversion efficiency of the solar cell.

According to some embodiments of the present application, an aspect of an embodiment of the present application provides a solar cell, including: the substrate is provided with a first edge and a second edge, wherein the first edge is the edge of the substrate along the first direction, and the second edge is the edge of the substrate along the second direction; the passivation layer is positioned on the substrate; the auxiliary electrodes are arranged on the substrate at intervals along the second direction, extend along the first direction and penetrate through the passivation layer to be in contact with the substrate; at least one main electrode, the main electrode is located passivation layer surface, and the main electrode includes: two connection pads near the second edge; a connecting line, wherein the port of the connecting line close to the second edge is closed, and a part of the surface of the connecting line except the port is contacted with each connecting pad; the first cross-sectional area of the connection line between the connection pad and the adjacent second edge is greater than the second cross-sectional area of the connection line between the connection pads.

In some embodiments, the difference between the first cross-sectional area and the second cross-sectional area is proportional to the size of the separation between the connection pad and the adjacent second edge.

In some embodiments, a first width of the connection line between the connection pads and the second edge is greater than a second width of the connection line between the connection pads.

In some embodiments, further comprising: at least one second connection pad located between adjacent connection pads; the connecting wire is contacted with each second connecting pad; for the same main electrode, the third cross-sectional area of the connecting line between two adjacent second connecting pads is smallest.

In some embodiments, a fourth cross-sectional area of a connecting line between the connecting pad and the second connecting pad is greater than or equal to the third cross-sectional area.

In some embodiments, the area of the connection pad is greater than the area of the second connection pad.

In some embodiments, the main electrode comprises: two first main electrodes, the first main electrodes being adjacent to the first edge; and the second main electrode is positioned between the adjacent first main electrodes, and the second main electrode is positioned on the surface of the passivation layer.

In some embodiments, the first main electrode comprises: two first sub-connection pads near the second edge, a first connection line, and a port of the first connection line near the second edge is closed, and a part of the surface of the first connection line except the port is contacted with each first sub-connection pad; the fifth cross-sectional area of the first connection line between the first sub-connection pads and the adjacent second edge is greater than the sixth cross-sectional area of the first connection line between the first sub-connection pads.

In some embodiments, the second main electrode comprises: and the second connecting line is closed near the port of the second edge, and the sectional area of the first connecting line is larger than or equal to that of the second connecting line.

In some embodiments, the second main electrode further comprises: the second sub-connecting pad is close to the second edge and is contacted with the second connecting wire; along the second direction, the first distance between the first sub-connection pad and the second edge is greater than the second distance between the second sub-connection pad and the second edge.

In some embodiments, the junction of the first edge and the second edge has a chamfer, the first main electrode is adjacent to the chamfer, and the first sub-connection pad is located at an edge region of the chamfer other than the chamfer along the second direction.

In some embodiments, the solar cell is a back contact cell, the secondary electrode comprising: first and second electrodes arranged at intervals along the first direction; the main electrode includes: the first grid line structure is electrically connected with the first electrode, and the second grid line structure is electrically connected with the second electrode.

In some embodiments, the first gate line structure and the second gate line structure are arranged offset along the first direction.

In some embodiments, the cross-sectional area of the secondary electrode proximate the first edge is greater than the cross-sectional area of the secondary electrode distal the first edge in the first direction.

According to some embodiments of the present application, another aspect of the embodiments of the present application further provides a photovoltaic module, including: a cell string formed by connecting a plurality of solar cells according to any one of the above embodiments; the packaging layer is used for covering the surface of the battery string; and the cover plate is used for covering the surface of the packaging layer far away from the battery strings.

The technical scheme provided by the embodiment of the application has at least the following advantages:

in the solar cell provided by the embodiment of the application, the main electrode comprises the connecting pad and the connecting wire, the effective shading area can be reduced by setting the width of the connecting wire to be thinner, and meanwhile, the resistance loss is reduced, so that the total power of the component is improved. In addition, as the connecting lines forming the main grid are distributed more densely, contact points between the main grid and the fine grid can be more, and the current conduction paths at the hidden crack and the microcrack part of the silicon wafer are more optimized, the loss caused by microcrack is greatly reduced, and the improvement of the yield of the production line is facilitated. The first sectional area of the connecting line between the connecting pad and the adjacent second edge is larger than the second sectional area of the connecting line between the connecting pads, and the widths of the connecting lines between the second edge and the connecting pad are larger, so that the welding stress of the connecting pad can be relieved, and good contact is formed between the welding strip and the main electrode; in addition, the collection pressure of connecting pad can be alleviated to wider connecting wire, promotes the transmission capacity of carrier, and wider connecting wire has more transmission area and is used for collecting the electric current, and thinner connecting wire can reduce and shelter from the area, reduces optical loss.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, which are not to be construed as limiting the embodiments unless specifically indicated otherwise; in order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the drawings required for the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for those skilled in the art.

Fig. 1 is a schematic structural diagram of a solar cell according to an embodiment of the present application;

fig. 2 is a schematic view of a partial structure of a solar cell according to an embodiment of the application;

fig. 3 is a schematic structural diagram of a solar cell according to an embodiment of the present application;

fig. 4 is a schematic structural diagram of a first main electrode in a solar cell according to an embodiment of the application;

fig. 5 is a schematic view of another structure of a first main electrode in a solar cell according to an embodiment of the application;

Fig. 6 is a schematic structural diagram of a second main electrode in a solar cell according to an embodiment of the application;

fig. 7 is a schematic structural diagram of a sub-electrode in a solar cell according to an embodiment of the present application;

fig. 8 is a schematic structural diagram of a solar cell according to an embodiment of the present application;

fig. 9 is a schematic view of another partial structure of a solar cell according to an embodiment of the present application;

fig. 10 is a schematic structural diagram of a photovoltaic module according to an embodiment of the present application.

Detailed Description

As known from the background art, the photoelectric conversion efficiency of the solar cell in the prior art is poor.

Analysis has found that one of the reasons for the poor photoelectric conversion efficiency of the solar cell of the prior art is: in a conventional solar cell, because of the limitation of the refining process of monocrystalline silicon for preparing a substrate, a monocrystalline silicon rod can only be made into a circle at present, and the silicon rod is sliced after coming out, namely, the section of the silicon rod is sliced into a monocrystalline silicon wafer (after the area is calculated, the illumination area can be furthest increased in one unit, the silicon rod material can be furthest saved, the production of a cell slice and a component is also convenient), and a chamfer is usually arranged at the junction of the first edge and the second edge of the substrate, so that the stress outside the silicon wafer is reduced, and the micro damage of the corners of the silicon wafer is avoided. Meanwhile, in order to ensure that the welding strip does not exceed the battery chamfering position during welding, a certain distance is needed between the welding spot and the battery chamfering, so that the carrier transport path of the chamfering area is overlong, and the transport loss is increased. In addition, if the solder joint or the solder ribbon is close to the edge of the solar cell, hidden cracks of the solar cell may be caused in the subsequent lamination process, and the performance of the solar cell may be affected.

The embodiment of the application provides a solar cell, wherein a main electrode comprises a connecting pad and a connecting wire, the effective shading area can be reduced by setting the width of the connecting wire to be thinner, and meanwhile, the resistance loss is reduced, so that the total power of a component is improved. In addition, as the connecting lines forming the main grid are distributed more densely, contact points between the main grid and the fine grid can be more, and the current conduction paths at the hidden crack and the microcrack part of the silicon wafer are more optimized, the loss caused by microcrack is greatly reduced, and the improvement of the yield of the production line is facilitated. The first sectional area of the connecting line between the connecting pad and the adjacent second edge is larger than the second sectional area of the connecting line between the connecting pads, and the widths of the connecting lines between the second edge and the connecting pad are larger, so that the welding stress of the connecting pad can be relieved, and good contact is formed between the welding strip and the main electrode; in addition, the collection pressure of the connecting pad can be relieved by the wider connecting wire, the transmission capacity of carriers is improved, and the wider connecting wire has more transmission area for collecting current.

Embodiments of the present application will be described in detail below with reference to the attached drawings. However, it will be understood by those of ordinary skill in the art that in various embodiments of the present application, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the claimed technical solution of the present application can be realized without these technical details and various changes and modifications based on the following embodiments.

Fig. 1 is a schematic structural diagram of a solar cell according to an embodiment of the present application; fig. 2 is a schematic view of a partial structure of a solar cell according to an embodiment of the application; fig. 3 is a schematic structural diagram of a solar cell according to an embodiment of the present application; fig. 4 is a schematic structural diagram of a first main electrode in a solar cell according to an embodiment of the application; fig. 5 is a schematic view of another structure of a first main electrode in a solar cell according to an embodiment of the application; fig. 6 is a schematic structural diagram of a second main electrode in a solar cell according to an embodiment of the application; fig. 7 is a schematic structural diagram of a sub-electrode in a solar cell according to an embodiment of the present application; fig. 8 is a schematic structural diagram of a solar cell according to an embodiment of the present application; fig. 9 is a schematic view of another partial structure of a solar cell according to an embodiment of the application.

According to some embodiments of the application, referring to fig. 1 to 9, a solar cell includes: the substrate 100, the substrate 100 has a first edge 101 and a second edge 102, the first edge 101 is an edge of the substrate 100 along a first direction X, and the second edge 102 is an edge of the substrate 100 along a second direction Y; a passivation layer on the substrate 100; a plurality of sub-electrodes 120, the sub-electrodes 120 being arranged at intervals along the second direction Y on the substrate 100, the sub-electrodes 120 extending along the first direction X, the sub-electrodes 120 penetrating the passivation layer to contact the substrate 100; at least one main electrode 110, the main electrode 110 being located on the passivation layer surface, the main electrode 110 comprising: two connection pads 113 near the second edge 102; a connection line 114, the connection line 114 being closed near the port of the second edge 102, a portion of the surface of the connection line 114 other than the port being in contact with each connection pad 113; the first cross-sectional area of the connection line 114 between the connection pads 113 and the adjacent second edge 102 is greater than the second cross-sectional area of the connection line 114 between the connection pads 113.

In some embodiments, the solar cell may be a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell, or a multi-compound solar cell, which may be specifically a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenium solar cell, or a perovskite solar cell. The solar cell may also be any of PERC cell (Passivated Emitter and Rear Cell, passivated emitter and back cell), PERT cell (Passivated Emitter and Rear Totally-diffused cell, passivated emitter back surface full diffusion cell), TOPCon cell (Tunnel Oxide Passivated Contact, tunnel oxide passivation contact cell), HIT/HJT cell (Heterojunction Technology, heterojunction cell). Take the structure of the solar cell shown in fig. 2 as an example.

The substrate 100 is a region that absorbs incident photons to generate photogenerated carriers. In some embodiments, the substrate 100 is a silicon substrate 100, which may include one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 100 may also be silicon carbide, an organic material, or a multi-component compound. The multi-component compounds may include, but are not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenium, and the like. Illustratively, the substrate 100 in embodiments of the present application is a monocrystalline silicon substrate.

In some embodiments, the front surface of the substrate 100 is a light receiving surface that absorbs incident light, and the back surface of the substrate 100 is a backlight surface. The substrate 100 has a doping element therein, the doping element being of an N-type or a P-type, the N-type element being a group v element such As a phosphorus (P) element, a bismuth (Bi) element, an antimony (Sb) element, or an arsenic (As) element, and the P-type element being 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 100 is a P-type substrate 100, the internal doping element is P-type. For another example, when the substrate 100 is an N-type substrate, the internal doping element type is N-type.

In some embodiments, the substrate 100 includes opposing first and second surfaces 104, 105. Within the first surface 104 of the substrate 100 is an emitter 106, the emitter 106 having a different doping element type than the substrate 100. And the surface of the emitter 106 may have a textured structure, so that the reflectivity of the first surface 104 of the substrate 100 to the incident light is smaller, and thus the absorption and utilization rate of the light are larger.

The first direction X and the second direction Y may be perpendicular to each other, or may have an included angle smaller than 90 degrees, for example, 60 degrees, 45 degrees, 30 degrees, or the like, and the first direction X and the second direction Y may not be the same direction. For convenience of explanation and understanding, the embodiment uses the case that the first direction X and the second direction Y are perpendicular to each other as an example, and in a specific application, the angle between the first direction X and the second direction Y may be adjusted according to the actual needs and the application scenario, which is not limited in this embodiment.

In some embodiments, the junction between the first edge 101 and the second edge 102 has a chamfer 103, and the connection pad 113 is located at an edge area of the chamfer 103 other than the chamfer 103 along the second direction Y, so that the connection pad 113 is not located at an area opposite to the chamfer 103, and hidden cracks and micro cracks at the chamfer 103 during welding or lamination can be avoided; the connection pad 113 is close to the chamfer 103, so that the current collected at the chamfer 103 can be collected by the solder strip in the shortest transmission path, the path loss is reduced, and the cell efficiency of the solar cell is improved. Specifically, referring to fig. 1, the distance between the side of the connection pad 113 near the second edge 102 and the side of the chamfer 103 facing the connection pad is smaller or contiguous, so that the connection pad 113 can be considered to be located at an edge region of the chamfer 103 other than in the second direction Y. Where a smaller distance may refer to a distance less than the gate spacing between adjacent sub-electrodes 120.

In some embodiments, along the second direction Y, the length between the end of the connection pad 113 and the edge of the chamfer 103 along the second direction Y is less than or equal to the gate spacing between adjacent sub-electrodes 120, further illustrating that the current collected at the chamfer 103 can be collected by the solder strip with the shortest transmission path, reducing the path loss, and improving the cell efficiency of the solar cell.

In some embodiments, the passivation layer may have a single-layer structure or a stacked-layer structure, and the material of the passivation layer may be one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride oxide, titanium oxide, hafnium oxide, or aluminum oxide. The passivation layer may include a first passivation layer 111 and a second passivation layer 112, the first passivation layer 111 being located at a surface of the emitter 106 remote from the substrate 100, the first passivation layer 111 may be regarded as a front passivation layer, the second passivation layer 112 being located at the second surface 105 of the substrate 100, and the second passivation layer 112 may be regarded as a rear passivation layer.

In some embodiments, the sub-electrode 120 is a grid line of a solar cell for collecting and summarizing the current of the solar cell. The sub-electrode 120 may be sintered from a burn-through paste. The material of the sub-electrode 120 may be one or more of aluminum, silver, gold, nickel, molybdenum, or copper. In some cases, the sub-electrode 120 refers to a thin gate line or a finger gate line to distinguish from a main gate line or a bus bar. The sub-electrode 120 includes: the first electrode 121, the first electrode 121 penetrates the first passivation layer 111 to contact the emitter 106, and the first electrode 121 is regarded as an upper electrode or a front electrode; the second electrode 122, the second electrode 122 penetrates the second passivation layer 112 to be in contact with the second surface 105 of the substrate 100, and the second electrode 122 is regarded as a bottom electrode or a back electrode.

In some embodiments, the main electrode 110 is regarded as a main grid of the solar cell, where the main grid is not a main grid in a conventional sense, but is a bridge formed by connecting the connecting wire 114 with each sub-electrode 120, and the connecting pads 113 are used for collecting current by connecting solder strips, so that the width of the connecting wire 114 can be set thinner, the effective shading area is reduced, the resistance loss is reduced, and the total power of the assembly is increased; the main electrode 110 can be arranged densely, so that the path of current passing through the fine grid is shortened, and the photoelectric conversion efficiency of the solar cell is improved; the thinner connecting lines 114 and the connecting pads 113 can also avoid the risk of hidden cracks and microcracks of the silicon wafer, so that the main electrode 110 is arranged at the edge of the solar cell with hidden cracks and microcracks, the current collecting capacity at the edge is improved, and the current collecting or conducting path is more optimized.

In some embodiments, each connection line 114 is electrically connected to a respective sub-electrode 120 for collecting current from the respective sub-gate. The width of the connection line 114 is set to be thin, and the width of the connection line 114 is in the range of 20- μm to 200- μm, preferably, the width of the connection line 114 is in the range of 20 μm to 150 μm, and may be 28 μm, 58 μm, 98 μm, 135 μm or 150 μm. Thus, the width of the connection line 114 can reduce the shielding area, reduce the shadow loss of the contact gate line, and improve the current collection capability.

In some embodiments, the connection 114 is closed near the end of the second edge 102, unlike conventional harpoon connection, i.e., the connection 114 has only one connection to each connection pad 113, and the harpoon connection may increase the contact point between the main electrode and the auxiliary electrode and the transmission path, but conventional thinner connection may cause greater damage to the resistance of the main electrode, affecting the battery efficiency; only set up a connecting wire and the harpoon connecting wire that two piece at least connecting wires are constituteed and are compared, reduced the thick liquids cost, and be favorable to follow-up alignment of welding the area. Wherein the port near the second edge 102 is not in contact with the connection pad 113, and the connection pad 113 is in contact with an area other than the port of the connection line 114. Thus, when the corners of the substrate 100 are provided with the chamfer 103, the connection pads 113 are located in the opposite areas of the chamfer 103, and the connection lines 114 can be located in the opposite areas of the chamfer 103, so that the current at the chamfer 103 is collected, the carrier transport path at the area of the chamfer 103 is reduced, the transport loss is reduced, and the risk of damage caused by the arrangement of the connection pads 113 at the chamfer 103 can be avoided.

The cross-sectional area refers to the product of the width and the height, however, in order to avoid the risk of hidden or micro-cracking of the battery sheet due to different stress at the respective portions of the battery sheet during the subsequent connection with the solder strip or lamination process, the respective portions of the connection line 114 are generally disposed to have the same height, so that the first cross-sectional area is larger than the second cross-sectional area, and thus the first width of the connection line 114 between the connection pads 113 and the second edge 102 may be regarded as being larger than the second width of the connection line 114 between the connection pads 113.

In other embodiments, to avoid the risk of hidden cracking of the connection lines 114 near the edges, it is possible to provide the height of the connection lines 114 (i.e. the first sub-connection lines 116) between the connection pads 113 and the second edge 102 to be slightly smaller than the height of the connection lines 114 (i.e. the second sub-connection lines 117 and the third sub-connection lines 118) between the connection pads 113. Also, it may be pushed out that the first width of the connection line 114 between the connection pads 113 and the second edge 102 is larger than the second width of the connection line 114 between the connection pads 113. The width of the first sub-connection line 116 is larger, so that the welding stress of the connection pad 113 can be relieved, and good contact is formed between the welding strip and the main electrode 110; in addition, the wider first sub-connection line 116 can relieve the collection pressure of the connection pad 113, and improve the carrier transmission capability, and the wider first sub-connection line 116 has more transmission area for collecting current.

In some embodiments, the difference between the first cross-sectional area and the second cross-sectional area is proportional to the size of the spacing S between the connection pad 113 and the adjacent second edge 102. When the space S between the connection pad 113 and the adjacent second edge 102 is larger, the first cross-sectional area is also larger, i.e., the first width is also larger, so that the transmission area of the collecting current is also larger, thereby relieving the collecting pressure and improving the battery performance. The difference between the first cross-sectional area and the second cross-sectional area can be regarded as a difference between the first width and the second width, the difference between the first width and the second width is smaller than 100 μm, and further, the difference between the first width and the second width is smaller than 80 μm. The difference between the first width and the second width may in particular be 15 μm, 39 μm, 68 μm or 80 μm. Thus, the difference between the first width and the second width can meet the requirement that the width of the first sub-connecting line 116 is larger, the better the carrier collecting capability of the second edge is, the proper shielding area is, and the optical loss is reduced; the second sub-connection line 117 and the third sub-connection line 118 have appropriate cross-sectional areas, good conductivity and less resistance loss.

In some embodiments, the first width ranges from 20 μm to 200 μm, preferably the first width ranges from 20 μm to 150 μm, and may specifically be 28 μm, 58 μm, 98 μm, 135 μm or 150 μm. Thus, the width of the first sub-connection line 116 can reduce the shielding area, reduce the shadow loss of the contact gate line, and improve the current collection capability.

In some embodiments, the second width ranges from 20 μm to 100 μm, preferably the second width ranges from 20 μm to 80 μm, which may be, in particular, 28 μm, 39 μm, 52 μm, 71 μm or 80 μm. Thus, the cross-sectional areas of the second sub-connection lines 117 and the third sub-connection lines 118 are appropriate, the conductivity is good, and the resistance loss is small.

In some embodiments, the distance S between the connection pad 113 and the adjacent second edge 102 ranges from 3mm to 15mm, preferably, the distance S ranges from 3mm to 13mm, and the distance S may be 3mm, 5.8mm, 9.4mm, or 13mm. The distance between the connecting pad and the second edge 102 is moderate, so that carriers of the second edge 102 can be collected, and risks of hidden cracks, breakage and the like caused by welding the welding strip can be avoided.

In some embodiments, the connection pad 113 may be regarded as a contact point where the main electrode 110 contacts the bonding tape, and the connection pad 113 may or may not contact the sub-electrode 120, but is electrically connected to the sub-electrode 120 through the connection line 114.

In some embodiments, further comprising: at least one second connection pad 115, the second connection pad 115 being located between the connection pads 113; the connection line 114 is in contact with each of the second connection pads 115; for the same main electrode 110, the third cross-sectional area of the connection line 114 (i.e., the third sub-connection line 118) between two adjacent second connection pads 115 is minimized; or the connection line 114 comprises a first sub-connection line 116 between the second edge and the connection pad 113, a second sub-connection line 117 between the second connection pad and the connection pad, and a third sub-connection line 118 between adjacent second connection pads, the third cross-sectional area of the third sub-connection line 118 being minimal. In a specific example, the fourth cross-sectional area of the second sub-link 117 is equal to the third cross-sectional area. The width of the connection line 114 (the second sub-connection line 117 and the third sub-connection line 118) in the middle region is thin, and the gate line shielding area can be reduced. In another specific example, the fourth cross-sectional area of the second sub-connection line 117 is larger than the third cross-sectional area, so that the first cross-sectional area is the largest, the fourth cross-sectional area is the next smallest, the third cross-sectional area is the smallest, the shielding area of the middle area of the substrate 100 is ensured to be smaller, the width of the edge area is larger, and the connection line 114 is in good contact with the sub-electrode 120, thereby having better current collection capability.

In some embodiments, the area of the connection pad 113 is greater than the area of the second connection pad 115. When the area of the connecting pad 113 positioned at the edge is larger, the connecting pad can be used as a reference for aligning the welding strip, so that welding offset between the welding strip and the main electrode 110 is avoided; the larger area of the connection pad 113 can also relieve the welding pressure of the welding strip and improve the current collecting capacity of the edge.

In some embodiments, the main electrode provided by the application is a connection line composed of a plurality of sub-connection lines, and the width of the first sub-connection line 116 is larger than the widths of the second sub-connection line 117 and the third sub-connection line 118, compared with a connection line with only one decreasing or increasing width, the design mode of the connection line provided by the application is more beneficial to the alignment of welding strips, reduces the difficulty of the preparation process, and reduces the shielding area of the non-edge area of the substrate, thereby having higher photoelectric conversion efficiency.

In some embodiments, referring to fig. 3, the main electrode includes: two first main electrodes 130, the first main electrodes 130 being adjacent to the first edge 101; at least one second main electrode 140, the second main electrode 140 is located between adjacent first main electrodes 130, and the second main electrode 140 is located on the passivation layer surface.

In some embodiments, the first main electrode 130 includes: two first sub-connection pads 131 near the second edge 102; a first connection line 132, and the first connection line 132 is closed near the port of the second edge 102, and a portion of the surface of the first connection line 132 except the port is in contact with each first sub-connection pad 131; the fifth cross-sectional area of the first connection lines 132 between the first sub-connection pads 131 and the adjacent second edge 102 is greater than the sixth cross-sectional area of the first connection lines 132 between the first sub-connection pads 131.

In some embodiments, further comprising: at least one third sub-connection pad 133, the third sub-connection pad 133 being located between the first sub-connection pads 131; the first connection line 132 contacts each third sub-connection pad 133; for the same first main electrode 130, the seventh cross-sectional area of the first connection line 132 between two adjacent third sub-connection pads 133 is the smallest; or the first connection line includes a first connection section 134 located between the second edge and the first sub-connection pad 131, a second connection section 136 located between the third sub-connection pad and the first sub-connection pad, and a third connection section 137 located between the third sub-connection pads, the seventh cross-sectional area of the third connection section being the smallest. In a specific example, referring to fig. 4, the eighth cross-sectional area of the second connecting section 136 is equal to the seventh cross-sectional area. The width of the first connection line 132 of the middle region is thinner, and the gate line shielding area can be reduced. In another specific example, referring to fig. 5, the eighth cross-sectional area of the second connecting section 136 is greater than the seventh cross-sectional area. Thus, the fifth cross-sectional area is the largest, the eighth cross-sectional area is the smallest, the shielding area of the middle area of the substrate 100 is ensured to be smaller, the width of the edge area is larger, and the first connection line 132 is in good contact with the sub-electrode 120, thereby having good current collecting capability.

In some embodiments, the second main electrode 140 includes: the second connecting line 142, the port of the second connecting line 142 close to the second edge 102 is closed, the cross-sectional area of the first connecting line 132 is larger than or equal to the cross-sectional area of the second connecting line 142, and for the second main electrode 140 in the non-edge area, the second connecting line 142 with smaller width is arranged, so that the grid line shielding area of the second main electrode 140 is smaller; for the first main electrode 130 in the edge region, the first connection line 132 with a larger width is provided, so that the cross-sectional area of the electrical contact between the first connection line 132 and each sub-electrode 120 is increased, the resistance of the first connection line 132 is reduced, and compared with the second connection line 142 with a smaller thickness, the current collection and transmission capability of the first connection line 132 adjacent to the edge of the substrate 100 is improved, and further the overall edge current collection capability and photoelectric conversion efficiency of the solar cell are improved.

In some embodiments, the first spacing m between the first main electrode 130 and the adjacent second main electrode 140 is not equal to the second spacing n between the adjacent second main electrodes 140. In a specific example, the first interval m is greater than the second interval n, the first main electrode 130 is close to the first edge 101, the main electrode at the edge is set to be sparse, and risks of micro-cracking and the like of the battery piece can be avoided during welding and lamination. In another specific example, the first spacing m is smaller than the second spacing n, which ensures that the first main electrode 130 and the second main electrode 140 are denser at the edges, and the path of current from the auxiliary electrode 120 to the main electrode is shorter, thereby reducing losses and facilitating the ability of the electrodes to collect current at the edges.

In some embodiments, the first connection line 132 and the second connection line 142 are made of the same material, i.e., the first connection line 132 and the second connection line 142 are formed in the same manufacturing process.

In some embodiments, the second main electrode 140 further includes: a second sub-connection pad 141, the second sub-connection pad 141 being adjacent to the second edge 102, the second sub-connection pad 141 being in contact with the second connection line 142; along the second direction Y, the first distance between the first sub-connection pad 131 and the second edge 102 is greater than the second distance between the second sub-connection pad 141 and the second edge 102. Since the junction between the first edge 101 and the second edge 102 of the substrate 100 has the chamfer 103, the first sub-connection pad 131 is located away from the second edge 102, and the second sub-connection pad 141 is located closer to the second edge 102 than the first sub-connection pad 131, so that the current transmission path at the second edge 102 can be shortened, and the current collection capability of the second edge 102 can be improved.

In some embodiments, referring to fig. 3 and 6, one end of the second connection line 142 is closed near the port of the second edge 102, and a portion of the surface of the second connection line 142 except the port is in contact with the second sub-connection pad 141; the ninth cross-sectional area of the second connection line 142 (i.e., the fourth segment 144) between the second sub-connection pads 141 and the adjacent second edge 102 is greater than the tenth cross-sectional area of the second connection line 142 (i.e., the fifth segment 146) between the second sub-connection pads. The technical idea that the ninth sectional area is larger than the tenth sectional area and the technical effect achieved are the same as or similar to the technical idea that the first sectional area is larger than the second sectional area and the technical effect achieved, and are not repeated here.

In some embodiments, referring to fig. 3 and 7, the cross-sectional area of the sub-electrode 120 near the first edge 101 is greater than the cross-sectional area of the sub-electrode 120 far from the first edge 101 in the first direction X to enhance the current collection and transmission capability of the sub-electrode 120 at the first edge 101.

In some embodiments, the number of primary grids may be 0, i.e., the solar cell is a no primary grid cell, or the solar cell is an MBB (multi-primary grid) cell.

In some embodiments, referring to fig. 1 and 8, the main electrode is in contact with a side of the at least one connection pad proximate to the first edge 101. The connection line is closer to the first edge 101, the current collecting capacity of the connection line at the first edge 101 is enhanced, and the connection pad and the first edge 101 are at least separated by the width of one connection line, so that the problem of breakage caused by poor stress at the edge can be avoided during welding and lamination. The auxiliary electrode 120 contacts with the side of the connection pad away from the first edge 101, so that the current collected by the auxiliary electrode can be directly collected by the connection pad and converged on the solder strip, and the current transmission path is reduced.

In some embodiments, the solar cell is a back contact cell, such as an IBC (Interdigitated back contact ) cell, referring to fig. 9, the back contact cell comprises: a substrate 100, a third passivation layer 107 on the first surface 104 of the substrate 100; a first doped region 108 and a second doped region 109 on the second surface 105 of the substrate 100; a fourth passivation layer 119, wherein the fourth passivation layer 119 is located on the surface of the substrate 100 in the first doped region 108 and the second doped region 109; the first electrode 121, the first electrode 121 penetrates the fourth passivation layer 119 to be connected with the first doped region 108; the second electrode 122, the second electrode 122 penetrates the fourth passivation layer 119 to be connected with the second doped region 109. In other embodiments, a back contact battery includes: the substrate is positioned on the third passivation layer on the first surface of the substrate; the second surface of the substrate is provided with a first doped region, and the first doped region can have the same conductive type as the substrate or have different conductive types with the substrate; the tunneling oxide layer and the doped polysilicon layer are positioned on the second surface of the substrate; the fourth passivation layer is positioned on the surface of the first doped region and the doped polysilicon layer; the first electrode penetrates through the fourth passivation layer and is connected with the doped polysilicon layer; and the second electrode penetrates through the fourth passivation layer and is connected with the first doped region. In still other embodiments, a back contact battery includes: the substrate is positioned on the third passivation layer on the first surface of the substrate; the second surface of the substrate is provided with a tunneling oxide layer, a first doped polysilicon layer and a second doped polysilicon layer; the fourth passivation layer is positioned on the surfaces of the first doped polysilicon layer, the second doped polysilicon layer and the substrate; the first electrode penetrates through the fourth passivation layer and is connected with the first doped polycrystalline silicon layer; and the second electrode penetrates through the fourth passivation layer and is connected with the second doped polycrystalline silicon layer. It is understood that the first surface is a front surface of the silicon substrate, the second surface is a back surface of the silicon substrate, the first doped region is one of an N-type doped region or a P-type doped region, and the second doped region is the other of the N-type doped region or the P-type doped region.

It should be noted that, the "back contact cell" refers to a structure in which both the positive electrode and the negative electrode are in contact with the back surface of the substrate 100 and collect current, and does not refer to the front surface of the substrate 100.

In some embodiments, the back contact battery includes: the substrate 100, the substrate 100 has a first edge 101 and a second edge 102, the first edge 101 is an edge of the substrate 100 along a first direction X, and the second edge 102 is an edge of the substrate 100 along a second direction Y; a passivation layer on the substrate 100; a plurality of sub-electrodes 120, the sub-electrodes 120 being arranged at intervals along the second direction Y on the substrate 100, the sub-electrodes 120 extending along the first direction X, the sub-electrodes 120 penetrating the passivation layer to contact the substrate 100; at least one main electrode 110, the main electrode 110 being located on the passivation layer surface, the main electrode 110 comprising: two connection pads 113 near the second edge 102; a connection line 114, the connection line 114 being closed near the port of the second edge 102, a portion of the surface of the connection line 114 other than the port being in contact with each connection pad 113; the first cross-sectional area of the connection line 114 between the connection pads 113 and the adjacent second edge 102 is greater than the second cross-sectional area of the connection line 114 between the connection pads 113.

In some embodiments, the difference between the first cross-sectional area and the second cross-sectional area is proportional to the size of the separation between the connection pad and the adjacent second edge. The first width of the connecting line between the connecting pads and the second edge is greater than the second width of the connecting line between the connecting pads.

In some embodiments, the secondary electrode comprises: the first electrode 121 and the second electrode 122 are arranged at intervals along the first direction, the first electrode 121 is one of a positive electrode and a negative electrode, and the second electrode 122 is one of a positive electrode and a negative electrode. The embodiment of the present application takes the first electrode 121 as a positive electrode and the second electrode 122 as a negative electrode as an example. The sub-electrode 120 includes first electrodes 121 and second electrodes 122 arranged at intervals in the second direction Y.

In some embodiments, the main electrode comprises: the first gate line structures 151 and the second gate line structures 152 are arranged at intervals, the first gate line structures 151 are electrically connected to the first electrodes 121, and the second gate line structures 152 are electrically connected to the second electrodes 122. Specifically, the first main electrode includes a first edge gate line electrically connected to each of the first electrodes 121 and a second edge gate line electrically connected to each of the second electrodes 122. The second main electrode includes a first gate line and a second gate line.

In some embodiments, the first gate line structure 151 and the second gate line structure 152 are arranged in a staggered manner along the first direction X, so that the first gate line structure 151 near the second edge and the second gate line structure 152 near the second edge have different distances along the second direction Y, thereby reducing consumption of the solar cell metallization conductive silver paste, shortening the distance for collecting current in the thin gate direction, and reducing the debris rate. In addition, at least a part of the main grid can not be exposed to one end of the auxiliary electrode close to the second edge, so that the battery plate is attractive in appearance, the adaptive length of the positive electrode and the negative electrode of the battery plate is ensured, and the risk of short circuit between electrodes with different polarities can be avoided.

In the solar cell provided by the embodiment of the application, the main electrode 110 comprises the connection pad 113 and the connection line 114, and the effective shading area can be reduced by setting the width of the connection line 114 to be smaller, and meanwhile, the resistance loss is reduced, so that the total power of the component is improved. In addition, since the connection lines 114 forming the main gate are more densely distributed, the contact points between the main gate and the fine gate can be more, and the current conduction paths at the hidden crack and the microcrack part of the silicon wafer are more optimized, the loss caused by microcrack is greatly reduced, and the improvement of the yield of the production line is facilitated. The first cross-sectional area of the connecting line 114 between the connecting pad 113 and the adjacent second edge 102 is larger than the second cross-sectional area of the connecting line 114 between the connecting pads 113, and the width of the connecting line 114 between the second edge 102 and the connecting pad 113 is larger, so that the welding stress of the connecting pad 113 can be relieved, and good contact is formed between the welding strip and the main electrode 110; in addition, the wider connection line 114 can relieve the collection pressure of the connection pad 113, improve the carrier transmission capability, and has more transmission area for collecting current.

Correspondingly, the embodiment of the application also provides a photovoltaic module, referring to fig. 10, the photovoltaic module comprises a battery string, and the battery string is formed by connecting a plurality of solar cells 20 provided by the embodiment; an encapsulation layer 21, the encapsulation layer 21 being for covering the surface of the battery string; a cover plate 22, the cover plate 22 is used for covering the surface of the encapsulation layer 21 away from the battery strings. The solar cells 20 are electrically connected in whole or multiple pieces to form a plurality of cell strings, and the plurality of cell strings are electrically connected in series and/or parallel.

Specifically, in some embodiments, multiple battery strings may be electrically connected by conductive charges. The encapsulation layer 21 includes a first encapsulation layer 211 and a second encapsulation layer 212, wherein the first encapsulation layer 211 covers one of the front surface and the back surface of the solar cell 20, and the second encapsulation layer covers the other of the front surface and the back surface of the solar cell 20, and specifically, at least one of the first encapsulation layer 211 or the second encapsulation layer 212 may be an organic encapsulation film such as an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene co-elastomer (POE) film, or a polyethylene terephthalate (PET) film. In some embodiments, the cover 22 may be a glass cover, a plastic cover, or the like having a light-transmitting function. Specifically, the surface of the cover plate 22 facing the encapsulation layer 21 may be a concave-convex surface, thereby increasing the utilization rate of incident light. The cover 22 includes a first cover 221 and a second cover 222, wherein the first cover 221 is opposite to the first encapsulation layer 211, and the second cover 222 is opposite to the second encapsulation layer 212.

While the application has been described in terms of the preferred embodiment, it is not intended to limit the scope of the claims, and any person skilled in the art can make many variations and modifications without departing from the spirit of the application, so that the scope of the application shall be defined by the claims. Furthermore, the embodiments of the present application described in the specification and the illustrated figures are illustrative only and are not intended to be limiting as to the full scope of the application as claimed.

It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples of carrying out the application and that various changes in form and details may be made therein without departing from the spirit and scope of the application. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the application, and the scope of the application should be assessed accordingly to that of the appended claims.

Claims

1. A solar cell, comprising:

the substrate comprises a first edge and a second edge, wherein the first edge is an edge of the substrate along a first direction, and the second edge is an edge of the substrate along a second direction;

A passivation layer on the substrate;

the auxiliary electrodes are arranged on the substrate at intervals along the second direction, extend along the first direction and penetrate through the passivation layer to be in contact with the substrate;

at least one main electrode, said main electrode is located on the surface of said passivation layer, said main electrode comprises: two connection pads near the second edge; a connecting line, the connecting line being closed near a port of the second edge, a portion of a surface of the connecting line other than the port being in contact with each of the connecting pads; the first cross-sectional area of the connecting line between the connecting pad and the adjacent second edge is larger than the second cross-sectional area of the connecting line between the connecting pads;

at least two second connection pads located between adjacent ones of the connection pads; the connecting wires are contacted with each second connecting pad;

the connecting wire comprises a first sub-connecting wire, a second sub-connecting wire and a third sub-connecting wire which are sequentially connected, wherein the first sub-connecting wire is a connecting wire positioned between the connecting pad and the second edge, the second sub-connecting wire is a connecting wire positioned between the connecting pad and the second connecting pad, and the third sub-connecting wire is a connecting wire positioned between two adjacent second connecting pads; the first sub-connecting wire is contacted with the connecting pad;

The extending direction of the second sub-connecting wire and the extending direction of the third sub-connecting wire are the same as the second direction;

wherein each connecting wire is electrically connected with each auxiliary electrode;

the main electrode includes: two first main electrodes, the first main electrodes being adjacent to the first edge; the junction of the first edge and the second edge is provided with a chamfer, and the first main electrode is close to the chamfer.

2. The solar cell of claim 1, wherein a difference between the first cross-sectional area and the second cross-sectional area is proportional to a distance between the connection pad and the adjacent second edge.

3. The solar cell of claim 1, wherein a first width of the connection line between the connection pads and the second edge is greater than a second width of the connection line between the connection pads.

4. The solar cell according to claim 1, wherein the third cross-sectional area of the connection line between two adjacent second connection pads is smallest for the same main electrode.

5. The solar cell according to claim 4, wherein a fourth cross-sectional area of the connection line between the connection pad and the second connection pad is equal to or larger than the third cross-sectional area.

6. The solar cell of claim 4, wherein the area of the connection pad is greater than the area of the second connection pad.

7. The solar cell of claim 1, wherein the main electrode comprises: and at least one second main electrode, wherein the second main electrode is positioned between the adjacent first main electrodes, and the second main electrode is positioned on the surface of the passivation layer.

8. The solar cell of claim 7, wherein the first main electrode comprises: two first sub-connection pads near the second edge, a first connection line, and a port of the first connection line near the second edge is closed, a portion of a surface of the first connection line except the port is in contact with each of the first sub-connection pads; the fifth cross-sectional area of the first connection line between the first sub-connection pads and the adjacent second edge is greater than the sixth cross-sectional area of the first connection line between the first sub-connection pads.

9. The solar cell of claim 8, wherein the second main electrode comprises: and the second connecting line is closed near the port of the second edge, and the sectional area of the first connecting line is larger than or equal to that of the second connecting line.

10. The solar cell of claim 9, wherein the second main electrode further comprises: a second sub-connection pad adjacent to the second edge, the second sub-connection pad in contact with the second connection line; along the second direction, a first distance between the first sub-connection pad and the second edge is greater than a second distance between the second sub-connection pad and the second edge.

11. The solar cell of claim 8, wherein in the second direction, the first sub-connection pad is located at an edge region of the chamfer that is other than in the second direction.

12. The solar cell of claim 1, wherein the solar cell is a back contact cell, and the sub-electrode comprises: first and second electrodes arranged at intervals along the first direction; the main electrode includes: the first grid line structure is electrically connected with the first electrode, and the second grid line structure is electrically connected with the second electrode.

13. The solar cell of claim 11, wherein the first and second grid line structures are arranged offset along the first direction.

14. The solar cell of claim 1, wherein a cross-sectional area of the sub-electrode proximate the first edge is greater than a cross-sectional area of the sub-electrode distal the first edge in the first direction.

15. A photovoltaic module, comprising:

a battery string formed by connecting a plurality of solar cells according to any one of claims 1 to 14;

an encapsulation layer for covering the surface of the battery string;

and the cover plate is used for covering the surface, far away from the battery strings, of the packaging layer.