Solar cell and photovoltaic module

Abstract

Embodiments of the present application provide a solar cell and a photovoltaic module. The solar cell comprises: a semiconductor substrate; a first grid line arranged on the back surface of the semiconductor substrate along a first direction; and a second grid line arranged on the back surface of the semiconductor substrate along a second direction, the second grid line being electrically connected with the first grid line. The second grid line comprises a first sub-electrode and a second sub-electrode. The first sub-electrode comprises a first head and a first tail. The second sub-electrode comprises a second head and a second tail. The first head, the first tail, the second head and the second tail are arranged along the direction in which the second grid line extends. In the direction in which the first grid line extends, the width of the first head and the width of the second tail are greater than the width of the first tail and the width of the second head. In the direction perpendicular to the back surface of the semiconductor substrate, the thickness of the first head is greater than the thickness of the first tail, the second head and the second tail. Embodiments of the present application are conducive to improving the welding effect of the solar cell.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the photovoltaic technology field, in particular to a solar cell and photovoltaic module. BACKGROUND

[0002] The output power of the photovoltaic module is positively related to the absorbed solar light energy, the solar cell as the key material of the photovoltaic module, the photoelectric conversion efficiency and the circuit quality after the multiple solar cells are series-welded play a decisive role in the power generation efficiency and performance of the photovoltaic module.

[0003] When the solar cell is series-welded at the module end, the solar cell with the solder strip is conveyed to the welding area by the conveying belt, the solder strip is clamped and placed by the welding machine clamping jaw and conveyed by the conveying belt, the solder strip is prone to deviation due to the light weight of the solder strip, the overlap area of the solder strip and the electrode of the grid line is small or no overlap after the deviation, and the solder strip cannot be closely contacted due to the warping of the solder strip at the initial area of the contact with the grid line, so that the bonding effect of the solder strip and the electrode is poor, the local virtual welding and welding deviation of the cell string are caused, and the welding effect of the solar cell is affected.

[0004] How to improve the welding effect of the solar cell and avoid or reduce the hidden cracks between the cells in the module becomes a problem to be solved by the person skilled in the art. SUMMARY

[0005] The embodiment of the present application provides a solar cell and photovoltaic module, and the solar cell welding effect problem is solved.

[0006] In order to solve the above problems, the embodiment of the present application provides a solar cell, which comprises: a semiconductor substrate, the semiconductor substrate comprises opposite front and back surfaces; a first grid line, the first grid line is arranged on the back surface of the semiconductor substrate along a first direction; a second grid line, the second grid line is arranged on the back surface of the semiconductor substrate along a second direction, the second grid line is electrically connected with the first grid line, and the first direction is perpendicular to the second direction; the second grid line comprises a first sub-electrode and a second sub-electrode, the first sub-electrode comprises a first head and a first tail, the second sub-electrode comprises a second head and a second tail, and the first head, the first tail, the second head and the second tail are arranged along the direction in which the second grid line extends; in the direction in which the first grid line extends, the width of the first head and the width of the second tail are greater than the width of the first tail and the width of the second head; in the direction perpendicular to the back surface of the semiconductor substrate, the thickness of the first head is greater than the thickness of the first tail, the thickness of the second head and the thickness of the second tail.

[0007] Additionally, the thickness of the first sub-electrode gradually decreases in a direction from the first head to the first tail.

[0008] Additionally, the thickness of the first head is 9-13 microns and the thickness of the first tail is 7-11 microns in a direction perpendicular to the back surface of the semiconductor substrate.

[0009] Additionally, the thickness of the first head is 9-13 microns and the thickness of the first tail is 7-11 microns in a direction perpendicular to the back surface of the semiconductor substrate.

[0010] Additionally, the thickness of the first tail is the same as the thickness of the second sub-electrode in a direction perpendicular to the back surface of the semiconductor substrate.

[0011] Additionally, the width of the first sub-electrode gradually decreases in a direction from the first head to the first tail, and the width of the second sub-electrode gradually increases in a direction from the second head to the second tail.

[0012] Additionally, the width of the first head is the same as the width of the second tail in a direction along which the second gate line extends.

[0013] Additionally, the length of the first head is 13-17% of the length of the first sub-electrode in a direction along which the second gate line extends.

[0014] Additionally, the width of the first head is the same as the width of the second tail in a direction along which the first gate line extends, and the width of the first tail is the same as the width of the second head.

[0015] Additionally, the width of the first head is 2.4-2.8 mm and the width of the first tail is 1.3-1.7 mm.

[0016] Additionally, each of the first sub-electrode and the second sub-electrode adjacent to each other on the second gate line is an electrode group, and each of the second gate lines includes a plurality of the electrode groups.

[0017] Additionally, the number of the electrode groups is an even number, and each of two adjacent electrode groups is arranged in a central symmetry, wherein the first sub-electrode of each of the electrode groups is close to the center of symmetry.

[0018] Additionally, the number of the electrode groups is an odd number greater than 1, and each of two adjacent electrode groups is arranged in a central symmetry, wherein the first sub-electrode of each of the electrode groups is close to the center of symmetry, and the second sub-electrode in a remaining electrode group close to the edge of the solar cell piece is close to the edge of the solar cell piece.

[0019] The embodiment of the present application also provides a photovoltaic module, comprising: a plurality of solar cell pieces as claimed in any one of claims 1-13, the plurality of solar cell pieces form a cell string through a welding strip; a cover plate, the cover plate is located on opposite sides of the cell string; and a layer of adhesive film, the layer of adhesive film is located between the cell string and the cover plate.

[0020] In addition, the solar cell piece is one of a half, a third, a quarter, a fifth or a sixth slice of the solar cell piece.

[0021] Compared with the prior art, the technical scheme provided by the embodiment of the present application has the following advantages:

[0022] The solar cell piece provided by the embodiment of the present application has the following advantages: in the direction in which the first grid line extends, the width of the first head and the width of the second tail are greater than the width of the first tail and the width of the second head, so that even if the welding strip on the second grid line is offset, the two ends of the offset welding strip have a large overlap area with the first head and the second tail due to the wide width of the first head and the second tail at the two ends of the second grid line, thereby improving the welding effect of the solar cell piece; meanwhile, in the direction perpendicular to the back surface of the semiconductor substrate, the thickness of the first head is greater than the thickness of the first tail, the thickness of the second head and the thickness of the second tail, so that even if the starting area of the welding strip in contact with the second grid line is warped, the thick first head can be in close contact with the welding strip, thereby avoiding the phenomenon of false welding in the subsequent welding process, and the thick first head will not form a protruding part after welding because a thick molten solder is needed to bond the welding strip and the second grid line with the paste during the welding process.

[0023] In the direction in which the first grid line extends, the width of the first head and the width of the second tail are the same, and the width of the first tail and the width of the second head are the same, so that the widths of the two ends of different sub-electrodes in each second grid line are the same, and no matter which end of the two ends of the welding strip in contact with the two ends of the second grid line has a greater offset, the contact area of the welding strip with the second grid line will not be too small; and the widths of different sub-electrodes are the same, so that the layout of the cell piece is more regular, which is conducive to the implementation of subsequent steps. BRIEF DESCRIPTION OF DRAWINGS

[0024] One or more embodiments are illustrated by way of example in the figures that form a part of this patent document, these example are not intended to limit the embodiments, elements having the same reference numbers in the figures indicate like elements unless otherwise expressly stated, the figures in the drawings do not constitute a proportional limitation.

[0025] Figure 1 It is a top view structural schematic diagram of a solar cell piece;

[0026] Figure 2 For Figure 1 A schematic view of a top structure of the second gate line in the embodiment;

[0027] Figure 3 For Figure 1 A schematic view of a sectional structure of the second gate line along a direction perpendicular to a surface of the semiconductor substrate in the embodiment;

[0028] Figure 4 For Figure 1 A schematic view of a welding effect of the second gate line and the solder strip in the embodiment;

[0029] Figure 5 A schematic view of a top structure of a solar cell provided by an embodiment of the present application;

[0030] Figure 6 A schematic view of a top structure of a sliced solar cell provided by an embodiment of the present application;

[0031] Figure 7 For Figure 6 A schematic view of a top structure of the second gate line in the embodiment;

[0032] Figure 8 A schematic view of a top structure of another second gate line provided by an embodiment of the present application;

[0033] Figure 9 For Figure 6 A schematic view of a sectional structure of the second gate line along a direction perpendicular to a surface of the semiconductor substrate in the embodiment;

[0034] Figure 10 A schematic view of a sectional structure of another second gate line along a direction perpendicular to a surface of the semiconductor substrate provided by an embodiment of the present application;

[0035] Figure 11 For Figure 6 A schematic view of a welding effect of the second gate line and the solder strip in the embodiment;

[0036] Figure 12 A schematic view of a structure of a photovoltaic module provided by an embodiment of the present application. DETAILED DESCRIPTION

[0037] As known from the background, the welding effect of the solar cell in the prior art is not good.

[0038] When solar cells are tandemly soldered to the module, the soldering machine pulls out a section of solder ribbon each time and places it on the main grid line on the back of the solar cell using vacuum adsorption. Each section of solder ribbon contacts two electrodes on one main grid line of a solar cell. Then, the solar cell with the solder ribbon is conveyed to the soldering area by a conveyor belt. In a high-temperature environment, the solder ribbon pressure pins apply downward pressure to the front of the solder ribbon and provide molten solder and paste at high temperature to bond the solder ribbon to the main grid line, thereby completing the soldering operation and connecting the positive and negative electrodes of two adjacent solar cells. However, during the process of being held by the soldering machine's grippers and conveyed by the conveyor belt, the solder ribbon is prone to shifting due to its light weight, and it is also prone to warping in the initial area where it contacts the grid line.

[0039] Figure 1 This is a top view schematic diagram of a solar cell structure; Figure 2 for Figure 1 A top view of the structure of the second grid line in the middle;

[0040] Figure 3 for Figure 1 A schematic diagram of the cross-sectional structure of the second gate line along the direction perpendicular to the surface of the semiconductor substrate.

[0041] refer to Figures 1-3 A solar cell is provided, comprising: a semiconductor substrate 100, the semiconductor substrate 100 including opposing front and back sides; a first gate line 101 arranged along a first direction X on the back side of the semiconductor substrate 100; a second gate line 102 arranged along a second direction Y on the back side of the semiconductor substrate 100, the second gate line 102 being electrically connected to the first gate line 101, the first direction X being perpendicular to the second direction Y; the second gate line 102 including a first sub-electrode 112 and a second sub-electrode 122, the first sub-electrode 112 including a first head 132 and a first tail 142. The second sub-electrode 122 includes a second head 152 and a second tail 162. The first head 132, the first tail 142, the second head 152 and the second tail 162 are arranged along the direction of extension of the second gate line 102. In the direction of extension of the first gate line 101, the width of the first head 132, the width of the second tail 162, the width of the first tail 142 and the width of the second head 152 are the same. In the direction perpendicular to the back surface of the semiconductor substrate 100, the thickness of the first head 132, the thickness of the first tail 142, the thickness of the second head 152 and the thickness of the second tail 162 are also the same.

[0042] The first grid line 101 is a sub-grid line of the solar cell, the second grid line 102 is a main grid line of the solar cell, the second grid line 102 is electrically connected with the first grid line 101, and is used for collecting the current of the sub-grid line. Through the foregoing, it can be obtained that the top view and the side view of the first sub-electrode 112 and the second electrode 122 on the second grid line 102 are both rectangular, which indicates that the width and the thickness of the two ends of each electrode are consistent. In the subsequent soldering operation, the width of the two ends of the second grid line 102 in contact with the solder strip is relatively narrow, and the thickness of the first head 132, which is the initial area in contact with the solder strip, is also relatively small.

[0043] Figure 4 For Figure 1 The welding effect diagram of the second grid line and the solder strip.

[0044] As can be seen from the foregoing, in the soldering of the solar cell, the solder strip 103 on the second grid line 102 is prone to deviation, and the width of the two ends of the second grid line 102 in contact with the solder strip 103 is relatively narrow, which cannot compensate for the deviation of the solder strip 103. When the deviation of the solder strip 103 exceeds half of the width of the electrode of the second grid line 102, the contact area between one end of the deviated solder strip 103 and the electrode becomes small or even no contact, which leads to poor bonding effect between the solder strip 103 and the electrode, causes partial soldering deviation of the battery string, and affects the soldering effect of the solar cell. The solder strip 103 is prone to warping at the initial area in contact with the second grid line 102, cannot be in close contact, and the initial area in contact with the second grid line 102 is the first head 132 of the first sub-electrode 112. The thickness of the first head 132 is relatively small, and the first head 132 with the small thickness is difficult to contact the warped solder strip 103, which leads to poor bonding effect between the solder strip 103 and the electrode, causes partial virtual welding of the battery string, and affects the soldering effect of the solar cell.

[0045] To solve the above problems, the embodiment of the present application provides a solar cell. In the direction in which the first grid line extends, the width of the first head and the width of the second tail are greater than the width of the first tail and the width of the second head. In the subsequent soldering process, even if the solder strip on the second grid line deviates, the width of the first head and the second tail at the two ends of the second grid line is relatively wide, and the two ends of the deviated solder strip also have a large overlap area with the first head and the second tail, which improves the soldering effect of the solar cell. At the same time, in the direction perpendicular to the back surface of the semiconductor substrate, the thickness of the first head is greater than the thickness of the first tail, the thickness of the second head, and the thickness of the second tail. Since the thickness of the first head is greater than the thickness of other regions of the second grid line, even if the initial area in contact with the solder strip of the second grid line warps, the thick first head can be in close contact with the solder strip, avoiding the phenomenon of virtual welding in the subsequent soldering process. In the soldering process, a relatively thick molten solder paste is needed to bond the solder strip and the second grid line, so the thick first head will not form a protruding part after soldering.

[0046] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. However, those skilled in the art can understand that, in the embodiments of the present application, many technical details are presented in order to make the readers better understand the present application. However, the technical solutions claimed by the present application can be implemented even without these technical details and based on various changes and modifications of the following embodiments.

[0047] Figure 5 A schematic top view of a solar cell provided by an embodiment of the present application; Figure 6 A schematic top view of a sliced solar cell provided by an embodiment of the present application.

[0048] The semiconductor substrate 200 includes opposite front and back surfaces; the first grid lines 201 are arranged on the back surface of the semiconductor substrate 200 along a first direction X; the second grid lines 202 are arranged on the back surface of the semiconductor substrate 200 along a second direction Y, the second grid lines 202 are electrically connected with the first grid lines 201, and the first direction X is perpendicular to the second direction Y; the second grid lines 202 include the first sub-electrodes 212 and the second sub-electrodes 222.

[0049] In the embodiment, the solar cell can be a double-sided cell, and under direct or indirect irradiation of sunlight, electronic transition occurs inside the double-sided cell to form a tiny current, which is then collected by a plurality of sub-grid lines and main grid lines to form a larger current and then output externally to realize conversion of light energy into electrical energy. In other embodiments, the solar cell is a single-sided cell, and the front surface of the solar cell is a light-receiving surface, and the back surface is a back light surface.

[0050] The material of the semiconductor substrate 200 can be a silicon wafer such as a single crystal silicon wafer, a polycrystalline silicon wafer or a single-crystal silicon-like wafer, and the quality of the silicon wafer directly determines the conversion efficiency of the solar cell.

[0051] The semiconductor substrate 200 is used to receive sunlight and generate photo-generated carriers, and includes opposite front and back surfaces. It can be understood that when the solar cell is a double-sided cell, the front and back surfaces of the semiconductor substrate 200 can both be surfaces for receiving sunlight. In other embodiments, when the solar cell is a single-sided cell, the front surface of the semiconductor substrate is a light-receiving surface, and the back surface is a back light surface.

[0052] In this embodiment, the semiconductor substrate 200 has an emitter, and the semiconductor substrate 200 has a PN junction structure. If the intrinsic material of the semiconductor substrate 200 is a P-type monocrystalline silicon layer, the emitter thereof is an N-type diffusion layer. If the intrinsic material of the semiconductor substrate 200 is an N-type monocrystalline silicon layer, the emitter thereof is a P-type diffusion layer.

[0053] Since the plurality of battery pieces need to be connected to form a battery string through a subsequent welding operation, the welding operation forms a solder strip on the surface of the battery piece, which reduces the light-receiving surface of the surface. Although the front surface and the back surface of the bifacial battery piece generate current under the irradiation of sunlight, the photoelectric conversion efficiency of the back surface of the bifacial battery piece is lower than that of the front surface. Therefore, a subsequent welding operation needs to be performed on the back surface of the bifacial battery piece to reduce the influence of the solder strip on the photoelectric conversion efficiency of the battery piece.

[0054] In this embodiment, the first gate line 201 on the back surface of the semiconductor substrate 200 is a sub-gate line, which can be 50-120, specifically 70, 90, or 110, and is arranged relatively densely to collect the micro-current generated on the back surface of the entire battery piece. The second gate line 202 perpendicular to the extension direction of the first gate line 201 and electrically connected to the first gate line 201 is used to collect the micro-current collected by the plurality of first gate lines 201, facilitating the subsequent transmission of the current. It can be understood that in other embodiments, the front surface of the semiconductor substrate also has a first gate line extending in the first direction and a second gate line extending in the second direction, which is used to collect the current formed on the front surface of the solar cell piece.

[0055] The number of second gate lines 202 on the back surface of the semiconductor substrate 200 can be 5-12, and the number of second gate lines 202 is positively correlated with the size of the solar cell piece. In this embodiment, a five-gate battery piece is taken as an example for illustration.

[0056] The second gate line 202 includes a first sub-electrode 212 and a second sub-electrode 222, and the first sub-electrode 212 and the second sub-electrode 222 are electrode silver paste, which is used to contact the solder strip in the subsequent process and transmit the current of the solar cell piece.

[0057] In this embodiment, the first sub-electrode 212 and the second sub-electrode 222 are connected by a gate line, which is doped polysilicon and has a conductive effect. Since the photoelectric conversion rate of the back surface of the solar cell piece is low, the second gate line 202 is all electrode silver paste, which has a low cost performance. Connecting a plurality of electrodes on each second gate line 202 through the gate line is beneficial to improving the cost performance of the battery piece.

[0058] In the direction extending along the second grid line 102, the length of the first sub-electrode 212 is 14.4-18.4 mm, and can be 15.4 mm, 16.4 mm or 17.4 mm; the length of the second sub-electrode 222 is 22-26 mm, and can be 23 mm, 24 mm or 15 mm. Since the first sub-electrode 212 is the starting area of the solder strip in contact with the second grid line 202, the solder strip in the starting area will be slightly warped, so the contact effect of the first sub-electrode 212 with the solder strip is not as good as the contact effect of the second sub-electrode 222 with the solder strip. In the embodiment, the length of the second sub-electrode 222 is greater than the length of the first sub-electrode 212, which is conducive to improving the soldering effect of the solar cell piece.

[0059] In the embodiment, each first sub-electrode 212 and a second sub-electrode 222 adjacent to each other on the second grid line 202 form an electrode group, and each second grid line 202 includes a plurality of electrode groups.

[0060] Continuing to refer to Figure 5 When the number of electrode groups is even, each adjacent two electrode groups are arranged in central symmetry, and the first sub-electrode of each electrode group is close to the center of symmetry.

[0061] In the embodiment, the whole solar cell piece can be divided into a plurality of cut solar cell pieces by laser cutting along each center of symmetry, and each second grid line 202 on each cut solar cell piece has an electrode group. Since the size of the cut solar cell piece is small, it is conducive to filling more cell pieces in the photovoltaic module in the subsequent process, increasing the effective power generation area of the photovoltaic module, and the current of the cut solar cell piece is small, which can improve the power loss of the photovoltaic module and comprehensively improve the power of the photovoltaic module.

[0062] Referring to Figure 6 The arrangement mode of the electrode group provided in the embodiment is that after the solar cell piece is cut along each center of symmetry, the first sub-electrode 212 is close to the cutting surface.

[0063] As can be seen from the above, the shorter first sub-electrode 212 is better as the starting welding point when welding is performed. Since the side of the solar cell piece far from the starting welding point needs to be fixed when welding is performed, the fixed side needs to bear a large pressure. In the embodiment, the first sub-electrode 212 is close to the cutting surface, that is, the starting welding point is close to the cutting surface, and the cutting surface does not bear a large pressure, effectively avoiding the risk of hidden cracks of the cutting surface with weak stress capacity under a large pressure, and improving the reliability of the solar cell piece.

[0064] In other embodiments, the number of electrode groups is an odd number greater than 1, and each adjacent two electrode groups are arranged in a center symmetry, wherein the first sub-electrode of each electrode group is close to the center of symmetry, and the second sub-electrode of the remaining electrode group close to the edge of the solar cell wafer is close to the edge of the solar cell wafer.

[0065] The number of electrode groups is an odd number greater than 1, and the number of the remaining electrode groups except for the electrode group close to the edge of the solar cell wafer is an even number, and the arrangement and cutting of the even number of electrode groups are the same as described above, which will not be repeated here; since there is only one electrode group on each second grid line of the sliced solar cell wafer, and the second sub-electrode close to the edge of the solar cell wafer in the electrode group close to the edge of the solar cell wafer, the first sub-electrode close to the cutting surface, when welding, the non-cutting surface receives greater pressure, which is beneficial to improve the reliability of the solar cell wafer.

[0066] Figure 7 For Figure 6 the top view structure diagram of the second grid line.

[0067] Reference Figure 7 , in the embodiment, the first sub-electrode 212 includes a first head 232 and a first tail 242, the second sub-electrode 222 includes a second head 252 and a second tail 262, and the first head 232, the first tail 242, the second head 252 and the second tail 262 are arranged along the direction in which the second grid line 202 (refer to Figure 6 ) extends; in the direction in which the first grid line 201 (refer to Figure 6 ) extends, the width of the first head 232 and the width of the second tail 262 are greater than the width of the first tail 242 and the width of the second head 252.

[0068] In this way, in the subsequent welding process, even if the solder strip on the second grid line 202 is offset, since the width of the first head 232 and the second tail 262 at both ends of the second grid line 202 is wide, the two ends of the offset solder strip also have a large contact area with the first head 232 and the second tail 262, and the offset welding condition is not formed, which improves the welding effect of the solar cell wafer.

[0069] In the embodiment, in the direction in which the first grid line 201 extends, the width of the first head 232 and the width of the second tail 262 are the same, and the width of the first tail 242 and the width of the second head 252 are the same.

[0070] In this way, the two ends of the different sub-electrodes in each second grid line 202 have the same width, and no matter which end of the two ends of the solder strip in contact with the second grid line 202 has a larger offset, the contact area of the solder strip with the second grid line 202 will not be too small. Moreover, the widths of the different sub-electrodes are the same, and the layout of the cell piece is more regular, which is beneficial to the implementation of subsequent steps.

[0071] In the embodiment, the width of the first head 232 is 2.4-2.8 mm, and can be 2.5 mm, 2.6 mm or 2.7 mm; the width of the first tail 242 is 1.3-1.7 mm, and can be 1.4 mm, 1.5 mm or 1.6 mm.

[0072] The sub-electrode of the traditional second grid line has a rectangular cross section in the extension direction of the first grid line, that is, the width of the first head is the same as the width of the first tail, and is specifically 2.1 mm. The width of the first head 232 and the width of the first tail 242 in the embodiment are thus set, which widens the first head 232 in contact with the end having the largest offset of the solder strip, and at the same time, the material required for the entire sub-electrode does not change greatly compared with the traditional sub-electrode, which improves the soldering effect without increasing the production cost.

[0073] Continuing to refer to Figure 7 In the direction from the first head 232 to the first tail 242, the width of the first sub-electrode 212 gradually decreases; in the direction from the second head 252 to the second tail 262, the width of the second sub-electrode 222 gradually increases.

[0074] It can be obtained that in the direction from the first sub-electrode 212 to the second sub-electrode 222, the cross section of the first sub-electrode 212 in the extension direction of the first grid line 201 is an inverted isosceles trapezoid, the cross section of the second sub-electrode 222 in the extension direction of the first grid line 201 is an isosceles trapezoid, and the side surface of the first sub-electrode 212 and the side surface of the second sub-electrode 222 are smooth transition inclined surfaces; since the side surface of the solder strip is also a smooth transition inclined surface when the solder strip is offset, the side surface of the sub-electrode can better contact the offset solder strip when the side surface of the sub-electrode is also an inclined surface.

[0075] Figure 8 Another top view structural schematic diagram of the second grid line provided by an embodiment of the present application.

[0076] Referring to Figure 8 In other embodiments, in the direction from the second head 252 to the second tail 262 of the second grid line 202 (refer to FIG. 2B), the width of the second sub-electrode 222 gradually increases. Figure 6The width of the first head 232 and the width of the second tail 262 are the same in the direction along which the solder strip extends. The first head 232 and the second tail 262 are a protrusion, which, while satisfying the condition that the two ends of the solder strip have a larger contact area, reduces the volume of the sub-electrode and saves costs.

[0077] In the direction along which the second gate line 202 extends, the length of the first head 232 is 13% to 17% of the length of the first sub-electrode 212, and can be 14%, 15%, or 16% in particular. The length of the first head 232 in this range, while reducing the volume of the sub-electrode, also ensures the contact area of the two ends of the solder strip with the second gate line 202.

[0078] Figure 9 For Figure 6 The cross-sectional structure of the second gate line in the direction perpendicular to the surface of the semiconductor substrate.

[0079] Reference Figure 9 In the direction perpendicular to the back surface of the semiconductor substrate 200, the thickness of the first head 232 is greater than the thickness of the first tail 242, the thickness of the second head 252, and the thickness of the second tail 262.

[0080] Since the thickness of the first head 232 is greater than the thickness of other regions of the second gate line 202, even if the initial region of contact between the solder strip and the second gate line 202 is warped, the thicker first head 232 can be in close contact with the solder strip, avoiding the phenomenon of false welding in the subsequent soldering process. In the process of soldering, a thicker molten solder is needed to bond the solder strip and the second gate line 202, so the thicker first head 232 will not form a protrusion after soldering.

[0081] In this embodiment, in the direction from the first head 232 to the first tail 242, the thickness of the first sub-electrode 212 gradually decreases.

[0082] It can be obtained that, in the direction from the first sub-electrode 212 to the second sub-electrode 222, the cross section of the first sub-electrode 212 in the direction perpendicular to the back surface of the semiconductor substrate 200 (refer to Figure 6 ) is an inverted right-angled trapezoid, and the surface of the first sub-electrode 212 is a smoothly transitioned inclined surface, which is more conducive to close contact with the solder strip. In other embodiments, the surface of the first sub-electrode can also be a smoothly transitioned curved surface.

[0083] In the embodiment, the thickness difference between the first head 232 and the first tail 242 in the direction perpendicular to the back surface of the semiconductor substrate 200 is 1-3 microns, and specifically can be 2 microns. The thickness difference between the first head 232 and the first tail 242 is small, which prevents the solder strip from being short-circuited and prevents the first head 232 from being too high to lift the solder strip and make the solder strip uneven.

[0084] Specifically, the thickness of the first head 232 in the direction perpendicular to the back surface of the semiconductor substrate 200 is 9-13 microns, and specifically can be 10 microns, 11 microns or 12 microns; and the thickness of the first tail 242 is 7-11 microns, and specifically can be 8 microns, 9 microns or 10 microns.

[0085] In the embodiment, the thickness of the first tail 242 is also the same as the thickness of the second sub-electrode 222 in the direction perpendicular to the back surface of the semiconductor substrate 200.

[0086] Because the solder strip in contact with the second sub-electrode 222 does not have the phenomenon of warping, the thickness of the second sub-electrode 222 can be the same as the thickness of the first tail 242, so that the surface of the soldered solder strip is more flat. It can be understood that the thickness of the second head 252 and the thickness of the second tail 262 are 7-11 microns.

[0087] Figure 10 Another schematic diagram of the cross-sectional structure of the second gate line in the direction perpendicular to the surface of the semiconductor substrate is provided for an embodiment of the present application.

[0088] Reference Figure 10 In other embodiments, the thickness of the first head 232 does not change in the direction along the second gate line 202 (reference Figure 6 ). The first head 232 is a protruding part, which satisfies the filling of the gap caused by the warping of the solder strip, reduces the volume of the sub-electrode, and saves the cost; and the thickness of the molten solder and paste used in the subsequent process of soldering the solder strip and the sub-electrode is 25-30 microns, which is much larger than the thickness of the first head 232. After the adhesion of the solder and the paste, the protruding first head 232 does not affect the flatness of the surface of the solder strip.

[0089] Figure 11 For Figure 6 the welding effect of the second gate line and the solder strip in the embodiment.

[0090] Reference Figure 11 , most of the area of the two ends of the offset solder strip 203 is still on the upper surface of the second gate line 202 (reference Figure 6 ), which improves the welding effect of the solar cell piece.

[0091] The effect of the soldering operation of the solar cell provided by the embodiment will be described in detail below in connection with examples.

[0092] Table 1 shows the improvement of the effect of the soldering of the solar cell.

[0093]

[0094] Table 1

[0095] In the example, the width of the first head 232 and the width of the second tail 262 of the solar cell provided by the embodiment are greater than the width of the first tail 242 and the width of the second head 252, and the thickness of the first head 232 is greater than the thickness of the first tail 242, the thickness of the second head 252 and the thickness of the second tail 262. The width and the thickness of the first head, the first tail, the second head and the second tail of another solar cell are the same. The effect after soldering is shown in Table 1. The solar cell provided by the embodiment has a cell string rework rate caused by virtual soldering and soldering deviation of 0.2%, while the solar cell has a cell string rework rate caused by virtual soldering and soldering deviation of 3.2%. The solar cell provided by the embodiment has a photovoltaic module rework rate caused by virtual soldering and soldering deviation of 0.04%, while the solar cell has a photovoltaic module rework rate caused by virtual soldering and soldering deviation of 2.50%. The solar cell provided by the embodiment has a photovoltaic module failure rate caused by virtual soldering and soldering deviation of 0.001%, while the solar cell has a photovoltaic module failure rate caused by virtual soldering and soldering deviation of 0.035%.

[0096] It can be obtained that the solar cell provided by the embodiment has a lower failure rate and rework rate in various aspects than the other solar cell, improves the soldering effect of the solar cell, and further improves the performance of the photovoltaic module.

[0097] The embodiment provides a solar cell. In the direction in which the first grid line 201 extends, the width of the first head 232 and the width of the second tail 262 are greater than the width of the first tail 242 and the width of the second head 252. In the subsequent soldering process, even if the solder strip 203 on the second grid line 202 is offset, the two ends of the offset solder strip 203 have a large contact area with the first head 232 and the second tail 262 due to the wide width of the first head 232 and the second tail 262 at the two ends of the second grid line 202, and the soldering effect of the solar cell is improved. Meanwhile, in the direction perpendicular to the back of the semiconductor substrate 200, the thickness of the first head 232 is greater than the thickness of the first tail 242, the thickness of the second head 252 and the thickness of the second tail 262. Since the thickness of the first head 232 is greater than the thickness of other regions of the second grid line 202, even if the initial region of the solder strip 203 in contact with the second grid line 202 is warped, the thick first head 232 can be in close contact with the solder strip 203, avoiding the phenomenon of false welding in the subsequent soldering process. In the soldering process, thick molten solder is needed to bond the solder strip 203 and the second grid line 202 with the paste, so the thick first head 232 will not form a protruding part after soldering.

[0098] Figure 12 A structural schematic diagram of a photovoltaic module is provided for an embodiment of the present application.

[0099] Reference Figure 12 Another embodiment of the present application further provides a photovoltaic module, which comprises: a plurality of solar cell pieces 301 provided by the above-mentioned embodiments, a plurality of solar cell pieces 301 form a cell string 310 through a solder strip 302; a cover plate, the cover plate is located on the opposite sides of the cell string 310; and a film layer, the film layer is located between the cell string 310 and the cover plate.

[0100] In the embodiment, the solar cell piece 301 can be one of one-half, one-third, one-fourth, one-fifth or one-sixth of a solar cell piece, and a plurality of sliced solar cell pieces can be connected through the solder strip 302 to form the cell string 310.

[0101] Since the solar cell piece 301 in the photovoltaic module provided by the embodiment is the same as the above-mentioned embodiments, the solar cell piece 301 in the embodiment comprises a first grid line and a second grid line perpendicular to each other, wherein the second grid line comprises a first sub-electrode and a second sub-electrode.

[0102] Reference Figure 7The first sub-electrode 212 includes a first head 232 and a first tail 242, and the second sub-electrode 222 includes a second head 252 and a second tail 262, and the first head 232, the first tail 242, the second head 252 and the second tail 262 are arranged along the direction in which the second grid line extends; in the direction in which the first grid line extends, the width of the first head 232 and the width of the second tail 242 are greater than the width of the first tail 242 and the width of the second head 252.

[0103] In this way, even if the solder strip 302 (refer to Figure 12 ) on the second grid line in the photovoltaic module is offset, but due to the wider width of the first head 232 and the second tail 262 at both ends of the second grid line, the two ends of the offset solder strip 302 also have a larger contact area with the first head 232 and the second tail 262, and the offset soldering condition is not formed, thereby improving the soldering effect of the solar cell piece and further improving the performance of the photovoltaic module.

[0104] Referring to Figure 9 , in the embodiment, the thickness of the first head 232 is greater than the thickness of the first tail 242, the thickness of the second head 252 and the thickness of the second tail 262.

[0105] Since the thickness of the first head 232 is greater than the thickness of other regions of the second grid line, even if the solder strip 302 (refer to Figure 12 ) and the starting region of the second grid line are warped, the thicker first head 232 can be in close contact with the solder strip 302, avoiding the phenomenon of virtual welding in the subsequent soldering process, and thicker molten solder is needed to bond the solder strip and the second grid line during the soldering process. Therefore, the thicker first head 232 will not form a protruding portion after soldering.

[0106] In the embodiment, the cover plate includes a front plate 305 and a back plate 306, the front plate 305 is the cover plate close to the sun side of the photovoltaic module, and the back plate 306 is the cover plate away from the sun side. The cover plate plays a protective and supporting role for the photovoltaic module; the photovoltaic module further includes: a lead wire, the lead wire is electrically connected to at least one solar cell piece 301 in the cell string 310, and the solar cell piece 301 is electrically connected to the junction box through the lead wire.

[0107] The adhesive film layer includes a first adhesive film layer 303 and a second adhesive film layer 304, the first adhesive film layer 303 is located between the front plate 305 and the cell string 310, and the second adhesive film layer 304 is located between the back plate 306 and the cell string 310.

[0108] The material of the adhesive film layer is EVA (Polyethylene vinylacetate) adhesive film layer or POE (Polyoxyethylene) adhesive film layer, the adhesive film layer encapsulates the photovoltaic module, prevents the contact between the moisture in the environment and the battery string 310, and prevents the power attenuation of the photovoltaic module.

[0109] Since the specific structure of the solar cell 301 of the photovoltaic module is the same as that of the solar cell in the above embodiment, the remaining deformation structure and effect can be referred to the description of the above embodiment, which will not be described here.

[0110] The embodiment of the present application provides a photovoltaic module, and the solar cell 301 in the photovoltaic module, in the direction in which the first grid line extends, the width of the first head 232 and the width of the second tail 262 are greater than the width of the first tail 242 and the width of the second head 252, even if the solder strip 302 on the second grid line in the photovoltaic module is offset, but since the width of the first head 232 and the second tail 262 at both ends of the second grid line is wide, the both ends of the offset solder strip 302 also have a large contact area with the first head 232 and the second tail 262, the welding effect of the solar cell 301 is improved, and the performance of the photovoltaic module is improved; meanwhile, the thickness of the first head 232 is greater than the thickness of the first tail 242, the thickness of the second head 252 and the thickness of the second tail 262, since the thickness of the first head 232 is greater than the thickness of other regions of the second grid line, even if the initial region of the solder strip 302 in contact with the second grid line is warped, the thicker first head 232 can also be in close contact with the solder strip 302, avoiding the phenomenon of false welding in the subsequent welding process, and thicker molten solder is needed to bond the solder strip 302 and the second grid line in the welding process, so the thicker first head 232 will not form a protruding part after welding, while improving the performance of the photovoltaic module, without affecting the photovoltaic module.

[0111] Those skilled in the art can understand that the above embodiments are specific embodiments for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, therefore the protection scope of the present application should be limited by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, include: A semiconductor substrate, the semiconductor substrate comprising opposing front and back sides; A first gate line is arranged along a first direction on the back side of the semiconductor substrate; A second gate line is arranged along a second direction on the back side of the semiconductor substrate, and the second gate line is electrically connected to the first gate line, wherein the first direction is perpendicular to the second direction; The second gate line includes a first sub-electrode and a second sub-electrode. The first sub-electrode includes a first head and a first tail. The second sub-electrode includes a second head and a second tail. The first head, the first tail, the second head, and the second tail are arranged along the direction in which the second gate line extends. In the direction in which the first gate line extends, the width of the first head and the width of the second tail are greater than the width of the first tail and the width of the second head. In a direction perpendicular to the back surface of the semiconductor substrate, the thickness of the first head is greater than the thickness of the first tail, the thickness of the second head, and the thickness of the second tail.

2. The solar cell according to claim 1, characterized in that, The thickness of the first sub-electrode gradually decreases in the direction from the first head to the first tail.

3. The solar cell according to claim 1, characterized in that, In a direction perpendicular to the back surface of the semiconductor substrate, the thickness difference between the first head and the first tail is 1 micrometer to 3 micrometers.

4. The solar cell according to claim 3, characterized in that, In a direction perpendicular to the back surface of the semiconductor substrate, the thickness of the first head is 9 micrometers to 13 micrometers, and the thickness of the first tail is 7 micrometers to 11 micrometers.

5. The solar cell according to claim 1, characterized in that, In a direction perpendicular to the back surface of the semiconductor substrate, the thickness of the first tail portion is the same as the thickness of the second sub-electrode.

6. The solar cell according to claim 1, characterized in that, The width of the first sub-electrode gradually decreases in the direction from the first head to the first tail; the width of the second sub-electrode gradually increases in the direction from the second head to the second tail.

7. The solar cell according to claim 1, characterized in that, In the direction extending along the second gate line, the width of the first head and the width of the second tail are the same.

8. The solar cell according to claim 7, characterized in that, In the direction extending along the second gate line, the length of the first head is 13% to 17% of the length of the first sub-electrode.

9. The solar cell according to claim 1, characterized in that, In the direction in which the first gate line extends, the width of the first head is the same as the width of the second tail, and the width of the first tail is the same as the width of the second head.

10. The solar cell according to claim 9, characterized in that, The width of the first head is 2.4 to 2.8 mm, and the width of the first tail is 1.3 to 1.7 mm.

11. The solar cell according to claim 1, characterized in that, Each first sub-electrode and a second sub-electrode adjacent on the second gate line constitute an electrode group, and each second gate line includes multiple electrode groups.

12. The solar cell according to claim 11, characterized in that, The number of electrode groups is even, and each pair of adjacent electrode groups is arranged in a centrally symmetrical manner, wherein the first sub-electrode of each electrode group is close to the center of symmetry.

13. The solar cell according to claim 11, characterized in that, The number of electrode groups is an odd number greater than 1. Each pair of adjacent electrode groups is arranged in a centrally symmetrical manner, wherein the first sub-electrode of each electrode group is close to the center of symmetry, and the second sub-electrode of the remaining electrode group is close to the edge of the solar cell.

14. A photovoltaic module, characterized in that, include: Multiple solar cells as described in any one of claims 1-13, wherein the multiple solar cells are formed into a cell string by solder ribbons; Cover plates, the cover plates being located on opposite sides of the battery string; An adhesive film layer is located between the battery string and the cover plate.

15. The photovoltaic module according to claim 14, characterized in that, The solar cell is one of a half-slice, one-third-slice, one-quarter-slice, one-fifth-slice, or one-sixth-slice.

Images