CN115602744A - Solar Cells and Photovoltaic Modules - Google Patents

Abstract

The embodiment of the invention provides a solar cell and a photovoltaic module, wherein the solar cell comprises: a semiconductor substrate; the first grid lines are arranged on the back of the semiconductor substrate along a first direction; the second grid line is arranged on the back of the semiconductor substrate along a second direction and is 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 part and a first tail part, the second sub-electrode comprises a second head part and a second tail part, and the first head part, the first tail part, the second head part and the second tail part are arranged along the extending direction of the second grid line; in the extending direction of the first grid line, the width of the first head part and the width of the second tail part are larger than the width of the first tail part and the width of the second head part; the first head portion has a thickness greater than thicknesses of the first tail portion, the second head portion, and the second tail portion in a direction perpendicular to the back surface of the semiconductor substrate. The embodiment of the invention is beneficial to improving the welding effect of the solar cell.

Description

Solar Cells and Photovoltaic Modules

technical field

Embodiments of the present invention relate to the field of photovoltaic technology, and in particular to a solar cell and a photovoltaic module.

Background technique

The amount of output power of photovoltaic modules is positively correlated with the absorbed solar energy. As the key material of photovoltaic modules, the photoelectric conversion efficiency of solar cells and the circuit quality of multiple solar cells connected in series play an important role in the power generation efficiency and performance of photovoltaic modules. play a decisive role.

When the solar cells are connected in series at the module end, the solar cells placed with the ribbon are conveyed to the welding area by the conveyor belt. During the process of the solder ribbon being clamped by the jaws of the welding machine and conveyed by the conveyor belt, the solder ribbon is light in weight and difficult to weld. The ribbon is prone to offset, and the overlapping area between the offset ribbon and the electrode of the grid line becomes smaller or has no overlap, and because the ribbon is easy to warp in the initial area of contact with the grid line, it cannot be in close contact, resulting in The bonding effect between the ribbon and the electrode becomes poor, resulting in local virtual welding and welding deviation of the battery string, which affects the welding effect of the solar cells.

How to improve the welding effect of the solar cells and avoid or reduce the cracks between the cells in the module has become an urgent problem to be solved by those skilled in the art.

Contents of the invention

Embodiments of the present invention provide a solar battery sheet and a photovoltaic module, which is beneficial to solve the problem of poor welding effect of the solar battery sheet.

In order to solve the above problems, an embodiment of the present invention provides a solar battery sheet, including: a semiconductor substrate, the semiconductor substrate includes opposite front and rear surfaces; first grid lines, the first grid lines are arranged along a first direction on the back side of the semiconductor substrate; a second gate line, the second gate line is arranged on the back side of the semiconductor substrate along a second direction, and the second gate line is electrically connected to the first gate line connection, 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 The second sub-electrode includes 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 gate line extends. Cloth; 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 the vertical In the direction of 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.

In addition, the thickness of the first sub-electrode gradually decreases in a direction along the direction from the first head to the first tail.

In addition, in a direction perpendicular to the back surface of the semiconductor substrate, the thickness difference between the first head portion and the first tail portion is 1 micrometer to 3 micrometers.

In addition, in a direction perpendicular to the back surface of the semiconductor substrate, the thickness of the first head is 9 microns to 13 microns, and the thickness of the first tail is 7 microns to 11 microns.

In addition, 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.

In addition, in the direction along the first head pointing to the first tail, the width of the first sub-electrode gradually decreases; in the direction along the second head pointing to the second tail, The width of the second sub-electrode gradually increases.

In addition, in a direction extending along the second gate line, the width of the first head portion is the same as the width of the second tail portion.

In addition, in a direction extending along the second gate line, the length of the first head is 13%-17% of the length of the first sub-electrode.

In addition, in the extending direction of the first gate line, the width of the first head is the same as that of the second tail, and the width of the first tail is the same as the width of the second head.

In addition, 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.

In addition, each of the first sub-electrodes and one of the second sub-electrodes adjacent to each other on the second grid line is an electrode group, and each of the second grid lines includes a plurality of the electrode groups.

In addition, the number of the electrode groups is an even number, and every two adjacent electrode groups are arranged symmetrically to the center, wherein the first sub-electrode of each electrode group is close to the symmetry center.

In addition, the number of the electrode groups is an odd number greater than 1, and every two adjacent electrode groups are arranged symmetrically about the center, wherein the first sub-electrode of each electrode group is close to the symmetrical center , the second sub-electrode in the remaining one of the electrode groups close to the edge of the solar cell is close to the edge of the solar cell.

An embodiment of the present invention also provides a photovoltaic module, comprising: a plurality of solar cells according to any one of claims 1-13, wherein a plurality of solar cells form a battery string through welding ribbons; a cover plate, the The cover plate is located on opposite sides of the battery string; the adhesive film layer is located between the battery string and the cover plate.

In addition, the solar battery sheet is one of half, third, quarter, fifth or sixth slices of the solar battery sheet.

Compared with the prior art, the technical solutions provided by the embodiments of the present invention have the following advantages:

In the solar cell sheet provided by the embodiment of the present invention, in the direction in which the first grid lines extend, the width of the first head and the width of the second tail are larger than the width of the first tail and the width of the second head, and the subsequent welding In the process, even if the solder strip on the second grid line is offset, but because the width of the first head and the second tail at the two ends of the second grid line is relatively wide, the two ends of the offset solder ribbon and the first head The first head and the second tail also have a larger overlapping area, which improves the welding effect of the solar cells; at the same time, in the direction perpendicular to the back of the semiconductor substrate, the thickness of the first head is greater than the thickness of the first tail, and the thickness of the second head The thickness of the first head and the thickness of the second tail, because the thickness of the first head is greater than the thickness of other areas of the second grid line, even if the initial area where the solder ribbon contacts the second grid line warps, the thicker first head The part can also be in close contact with the ribbon to avoid the phenomenon of virtual soldering in the subsequent welding process, and it is necessary to use thicker molten solder and paste to bond the ribbon and the second grid line during the soldering process, so A thicker first head does not form a raised portion after welding.

In the direction in which the first grid line extends, the width of the first head is the same as that of the second tail, and the width of the first tail is the same as the width of the second head, so that different sub-electrodes in each second grid line The widths at both ends are the same, no matter which end of the two ends of the solder strip in contact with the two ends of the second grid line has a larger offset, the contact area between the solder strip and the second grid line will not be too small; and The width and other data of different sub-electrodes are the same, and the layout of the battery sheet is more regular, which is beneficial to the implementation of the subsequent steps.

Description of drawings

One or more embodiments are exemplified by the pictures in the corresponding drawings, and these exemplifications do not constitute a limitation to the embodiments. Elements with the same reference numerals in the drawings represent similar elements. Unless otherwise stated, the drawings in the drawings are not limited to scale.

Fig. 1 is a top view structural schematic diagram of a solar cell;

FIG. 2 is a schematic top view of the second gate line in FIG. 1;

3 is a schematic cross-sectional view of the second gate line in FIG. 1 along a direction perpendicular to the surface of the semiconductor substrate;

Fig. 4 is a schematic diagram of the welding effect of the second grid line and the welding strip in Fig. 1;

Fig. 5 is a schematic top view structure diagram of a solar cell provided by an embodiment of the present invention;

FIG. 6 is a schematic top view of a sliced solar cell provided by an embodiment of the present invention;

FIG. 7 is a schematic top view of the second gate line in FIG. 6;

FIG. 8 is a schematic top view of another second gate line provided by an embodiment of the present invention;

9 is a schematic cross-sectional view of the second gate line in FIG. 6 along a direction perpendicular to the surface of the semiconductor substrate;

10 is a schematic cross-sectional view of another second gate line along a direction perpendicular to the surface of the semiconductor substrate according to an embodiment of the present invention;

Fig. 11 is a schematic diagram of the welding effect of the second grid line and the welding strip in Fig. 6;

Fig. 12 is a schematic structural diagram of a photovoltaic module provided by an embodiment of the present invention.

detailed description

It can be seen from the background art that the soldering effect of the solar cells in the prior art is not good.

When the solar cells are welded in series at the component end, the welding machine pulls out a section of ribbon each time, and places the ribbon on the busbar on the back of the solar cell by vacuum adsorption. Each section of ribbon is connected to a solar cell. The two electrodes on one of the main grid lines of the sheet are in contact, and then the solar cell sheet with the solder ribbon placed is transported to the welding area through the conveyor belt. In a high temperature environment, the solder ribbon pressure pin gives the front of the ribbon a downward pressure. , and provide solder and paste melted at high temperature to bond the ribbon and the busbar, thereby completing the welding operation and connecting the positive and negative electrodes of the two adjacent solar cells, but the ribbon is in the grip of the welding machine. During the process of placing and conveying by the conveyor belt, because the quality of the solder ribbon is relatively light, the solder ribbon is prone to offset, and because the solder ribbon is prone to warpage at the initial area where it contacts the grid lines.

Fig. 1 is a top view structural schematic diagram of a solar cell; Fig. 2 is a top view structural schematic diagram of the second grid line in Fig. 1;

FIG. 3 is a schematic cross-sectional view of the second gate line in FIG. 1 along a direction perpendicular to the surface of the semiconductor substrate.

Referring to FIGS. 1 to 3 , a solar cell sheet is provided, including: a semiconductor substrate 100, the semiconductor substrate 100 includes opposite front surfaces and rear surfaces; The back side of the substrate 100; the second gate line 102, the second gate line 102 is arranged on the back side of the semiconductor substrate 100 along the second direction Y, the second gate line 102 is electrically connected to the first gate line 101, and the first direction X is perpendicular to The second direction Y; the second gate line 102 includes a first sub-electrode 112 and a second sub-electrode 122, the first sub-electrode 112 includes a first head 132 and a first tail 142, and the second sub-electrode 122 includes a second head 152 and the 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 in which the second grid line 102 extends; in the direction in which the first grid line 101 extends , the width of the first head 132, the width 162 of the second tail, 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 of the semiconductor substrate 100, the thickness of the first head 132 , the thickness of the first tail portion 142, the thickness of the second head portion 152 and the thickness of the second tail portion 162 are also the same.

Wherein, the first grid line 101 is the auxiliary grid line of the solar cell, the second grid line 102 is the main grid line of the solar cell, and the second grid line 102 is electrically connected with the first grid line 101 for collecting the auxiliary grid line current. It can be obtained from the foregoing that the top view and side view of the first sub-electrode 112 and the second electrode 122 on the second gate line 102 are both rectangular, indicating that the width and thickness of both ends of the two electrodes are consistent. During the welding operation, the width of the two ends of the second gate line 102 in contact with the solder ribbon is narrower, and the thickness of the first head 132 as the initial area in contact with the solder ribbon is also smaller.

FIG. 4 is a schematic diagram of the welding effect of the second grid line and the welding ribbon in FIG. 1 .

It can be seen from the above that when soldering solar cells, the soldering strip 103 on the second grid line 102 is easy to shift, and because the width of the two ends of the second grid line 102 in contact with the soldering band 103 is narrow, it is impossible to compensate for the soldering band 103. 103 offset, the offset of the welding strip 103 exceeds half of the electrode width of the second grid line 102, and the contact area between one end of the offset welding strip 103 and the electrode becomes smaller or has no contact, resulting in the welding strip 103 and The electrode bonding effect is deteriorated, causing partial welding deviation of the battery string, which affects the welding effect of the solar cells; The initial area where 102 is in contact with the solder strip 103 is the first head 132 of the first sub-electrode 112, the thickness of the first head 132 is small, and the first head 132 with a small thickness is difficult to contact the warped solder strip 103, leading to poor bonding effect between the welding ribbon 103 and the electrodes, resulting in partial virtual welding of the battery strings and affecting the welding effect of the solar cells.

In order to solve the above problems, an embodiment of the present invention provides a solar battery sheet, in the direction in which the first grid lines extend, 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 Width, in the subsequent welding process, even if the solder strip on the second grid line is offset, but because the width of the first head and the second tail at both ends of the second grid line is wider, the offset solder strip The two ends and the first head and the second tail also have a larger overlapping area, which improves the welding effect of the solar cells; at the same time, in the direction perpendicular to the back of the semiconductor substrate, the thickness of the first head is greater than that of the first tail The thickness of the second head and the thickness of the second tail, because the thickness of the first head is greater than the thickness of other areas of the second grid line, even if the initial area where the solder ribbon contacts the second grid line warps, The thicker first head can also be in close contact with the ribbon to avoid the phenomenon of virtual soldering in the subsequent welding process, and it is necessary to use thicker molten solder and paste to bond the ribbon to the solder during the welding process. The second grid line, so the thicker first head will not form a raised portion after soldering.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art can understand that in each embodiment of the present invention, many technical details are provided for readers to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in this application can also be realized.

FIG. 5 is a schematic top view structure of a solar cell provided by an embodiment of the present invention; FIG. 6 is a schematic top view of a sliced solar cell provided by an embodiment of the present invention.

The semiconductor substrate 200, the semiconductor substrate 200 includes opposite front and back; the first gate line 201, the first gate line 201 is arranged on the back side of the semiconductor substrate 200 along the first direction X; the second gate line 202, the second gate line 202 Arranged on the back of the semiconductor substrate 200 along the second direction Y, the second gate line 202 is electrically connected to the first gate line 201, the first direction X is perpendicular to the second direction Y; the second gate line 202 includes a first sub-electrode 212 and the second sub-electrode 222 .

In this embodiment, the solar battery sheet can be a double-sided battery sheet, and the opposite front and back of the double-sided battery sheet are directly or indirectly irradiated by sunlight, and electronic transitions occur inside, thereby forming a small current, and then passing through several secondary batteries. The grid lines and the main grid lines are combined into a large current and then output to the outside, so as to realize the conversion of light energy into electrical energy. In other embodiments, the solar cell is a single-sided cell, the front side of the solar cell is a light-receiving side, and the back side is a backlight side.

Wherein, the material of the semiconductor substrate 200 may be a silicon wafer such as monocrystalline silicon, polycrystalline silicon or quasi-monocrystalline silicon, and the quality of the silicon wafer directly determines the conversion efficiency of the solar cell. Surface types of the semiconductor substrate 200 include: textured surface, polished surface or etched surface, etc. FIG.

The semiconductor substrate 200 is used to receive sunlight and generate photo-generated carriers, including the opposite front and back. It can be understood that when the solar cell is a double-sided solar cell, both the front and the back of the semiconductor substrate 200 can receive sunlight. The surface on which light is incident. In other embodiments, when the solar cell is a single-sided cell, the front side of the semiconductor substrate is the light-receiving side, and the back side is the backlight side.

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 single crystal silicon layer, its emitter is an N-type diffused layer; if the semiconductor substrate 200 The intrinsic material is an N-type single crystal silicon layer, and its emitter is a P-type diffusion layer.

Since multiple cells need to be connected by welding to form a battery string in the future, the solder strips formed on the surface of the cells will reduce the light-receiving surface of the surface, although the front and back of the double-sided cells will be exposed to sunlight. Current is generated under irradiation, but the photoelectric conversion efficiency of the back of the double-sided cell is lower than that of the front, so subsequent welding operations need to be performed on the back of the double-sided cell to reduce the impact of the welding ribbon on the photoelectric conversion efficiency of the cell.

In this embodiment, the first gate lines 201 located on the back of the semiconductor substrate 200 are sub-gate lines, which can be set to 50 to 120, specifically 70, 90 or 110, and the arrangement is relatively dense, which is used to collect the entire The micro-current generated on the back of the battery sheet, and the second grid line 202 perpendicular to the extension direction of the first grid line 201 and electrically connected to the first grid line 201 is used to collect the micro-current collected by multiple first grid lines 201, which is convenient for subsequent transmission of electric current. It can be understood that, in other embodiments, the front side of the semiconductor substrate also has a first grid line extending along the first direction and a second grid line extending along the second direction for collecting the current formed on the front side of the solar cells.

The number of the second grid lines 202 on the back of the semiconductor substrate 200 may be 5-12, and the number of the second grid lines 202 is positively correlated with the size of the solar cells. In this embodiment, a five-grid solar cell is taken as an example for illustration.

The second grid line 202 includes a first sub-electrode 212 and a second sub-electrode 222. The first sub-electrode 212 and the second sub-electrode 222 are electrode silver pastes, which are used for subsequent contact with the solder strips to transmit the current of the solar cells.

In this embodiment, the first sub-electrode 212 and the second sub-electrode 222 are connected by a grid line, and the grid line is doped polysilicon, which has the function of conducting electricity. The grid lines 202 are all made of electrode silver paste, and the cost performance is relatively low. Connecting multiple electrodes on each second grid line 202 through the grid lines is beneficial to improve the cost performance of the battery sheet.

In the direction extending along the second grid line 102, the length of the first sub-electrode 212 is 14.4 mm to 18.4 mm, specifically 15.4 mm, 16.4 mm or 17.4 mm; the length of the second sub-electrode 222 is 22 mm to 26 mm , specifically can be 23 mm, 24 mm or 15 mm. Since the first sub-electrode 212 is the initial region where the solder ribbon contacts the second grid line 202, the solder ribbon in the initial region will be slightly warped, so the contact effect between the first sub-region 212 and the solder ribbon is not as good as that of the second sub-electrode. The contact effect between the electrode 222 and the welding ribbon, in this embodiment, the length of the second sub-electrode 222 is greater than the length of the first sub-electrode 212, which is beneficial to improve the welding effect of the solar cells.

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

Continuing to refer to FIG. 5 , when the number of electrode groups is an even number, every two adjacent electrode groups are arranged symmetrically about the center, wherein the first sub-electrode of each electrode group is close to the center of symmetry.

In this embodiment, laser cutting technology can be used to divide the entire solar cell into multiple sliced solar cells along each symmetrical center, and each second grid line 202 on each sliced solar cell has an electrode group; Due to the small size of the sliced solar cells, it is beneficial to fill more cells in the photovoltaic module and increase the effective power generation area of the photovoltaic module, and the current of the sliced solar cells is small, which can improve the power loss of the photovoltaic module , comprehensively improve the power of photovoltaic modules.

Referring to FIG. 6 , according to the arrangement of the electrode groups provided in this embodiment, after the solar cells are cut along each symmetrical center, the first sub-electrode 212 is near the cut surface.

From the above, it can be seen that it is better to have a shorter first sub-electrode 212 as the solder starting point during the welding operation, because during the welding operation, the side of the solar cell away from the solder starting point needs to be fixed, and the fixed side needs to bear Greater pressure, the first sub-electrode 212 is close to the cutting surface in this embodiment, that is, the welding point is close to the cutting surface, and it is not the cutting surface that bears the greater pressure, which effectively avoids the cutting surface with weaker force capacity. The risk of cracking under high pressure improves the reliability of solar cells.

In other embodiments, the number of electrode groups is an odd number greater than 1, and every two adjacent electrode groups are arranged symmetrically about the center, wherein the first sub-electrode of each electrode group is close to the center of symmetry, and the rest are close to the solar cell. The second sub-electrode in an electrode group at the edge of the sheet is close to the edge of the solar battery sheet.

The number of electrode groups is an odd number greater than 1. Except for an electrode group near the edge of the solar cell, the number of the remaining electrode groups is an even number. The arrangement and cutting of the even number of electrode groups are the same as above. Repeat it again; because there is only one electrode group on each second grid line of the sliced solar cell, and in this electrode group near the edge of the solar cell, the second sub-electrode is closer to the edge of the solar cell, so it is close to the cutting The first sub-electrode is the first sub-electrode, and the non-cutting surface is the one that receives greater pressure during welding, which is beneficial to improving the reliability of the solar battery sheet.

FIG. 7 is a schematic top view of the second gate line in FIG. 6 .

7, in this 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, the first head 232, the first tail 242 A tail portion 242, a second head portion 252 and a second tail portion 262 are arranged along the direction in which the second grid line 202 (refer to FIG. 6) extends; on the direction in which the first grid line 201 (refer to FIG. 6) extends, the first head The width of the portion 232 and the width of the second tail portion 242 are greater than the width of the first tail portion 242 and the width of the second head portion 252 .

In this way, in the subsequent soldering process, even if the solder strips on the second grid line 202 are offset, due to the wide widths of the first head 232 and the second tail 262 at both ends of the second grid line 202, after the offset The two ends of the solder strips also have larger contact areas with the first head portion 232 and the second tail portion 262, which prevents partial welding and improves the welding effect of the solar cells.

In this embodiment, in the extending direction of the first gate line 201 , the width of the first head portion 232 is the same as that of the second tail portion 262 , and the width of the first tail portion 242 is the same as that of the second head portion 252 .

In this way, the widths of the two ends corresponding to different sub-electrodes in each second grid line 202 are the same, no matter which end of the two ends of the solder strip in contact with the two ends of the second grid line 202 has a greater offset, Neither will make the contact area between the solder ribbon and the second gate line 202 too small; and the data such as the width of different sub-electrodes is the same, so the layout of the battery sheet is more regular, which is beneficial to the implementation of the subsequent steps.

In this embodiment, the width of the first head 232 is 2.4-2.8 mm, specifically 2.5 mm, 2.6 mm or 2.7 mm; the width of the first tail 242 is 1.3-1.7 mm, specifically 1.4 mm or 1.5 mm or 1.6mm.

The sub-electrode of the traditional second grid line has a rectangular cross-section along the extending direction of the first grid line, that is, the width of the first head is the same as the width of the first tail, specifically 2.1 millimeters; The width of a head portion 232 and the width of the first tail portion 242 are set in such a way that while widening the first head portion 232 in contact with the end portion with the largest offset of the solder strip, the material required for the entire sub-electrode is different from that of the traditional Compared with the sub-electrodes, there is no major change, and while the welding effect is improved, the production cost is not increased.

Continuing to refer to FIG. 7, in the direction along the first head 232 to the first tail 242, the width of the first sub-electrode 212 gradually decreases; in the direction along the second head 252 to the second tail 262, the second The width of the sub-electrodes 222 gradually increases.

It can be obtained that, in the direction along 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 extending direction of the first gate line 201 is an inverted isosceles trapezoid, and the second sub-electrode 212 is an inverted isosceles trapezoid. The cross-section of the electrode 222 in the extending direction of the first grid line 201 is an isosceles trapezoid, and the side surfaces of the first sub-electrode 212 and the second sub-electrode 222 are slopes with smooth transition; The side of the ribbon is also a slope with a smooth transition. When the side of the sub-electrode is also a slope, it can better contact with the offset ribbon.

FIG. 8 is a schematic top view of another second gate line provided by an embodiment of the present invention.

Referring to FIG. 8 , in other embodiments, the width of the first head portion 232 is the same as the width of the second tail portion 262 in the direction extending along the second gate line 202 (refer to FIG. 6 ). The first head portion 232 and the second tail portion 262 are a protruding portion, which reduces the volume of the sub-electrode and saves cost while satisfying a larger contact area with the two ends with a larger offset of the solder strip.

Wherein, in the direction extending along the second gate line 202 , the length of the first head portion 232 is 13%-17% of the length of the first sub-electrode 212 , specifically 14%, 15% or 16%. If the length of the first head portion 232 is within this range, the contact area between the two ends of the solder strip and the second gate line 202 can be ensured while reducing the volume of the sub-electrode.

FIG. 9 is a schematic cross-sectional view of the second gate line in FIG. 6 along a direction perpendicular to the surface of the semiconductor substrate.

Referring to FIG. 9 , in a direction perpendicular to the back surface of the semiconductor substrate 200 , the thickness of the first head portion 232 is greater than the thickness of the first tail portion 242 , the thickness of the second head portion 252 and the thickness of the second tail portion 262 .

Since the thickness of the first head portion 232 is greater than the thickness of other areas of the second grid line 202, even if the initial area where the solder ribbon contacts the second grid line 202 warps, the thicker first head portion 232 can also contact the solder ribbon. close contact, avoiding the phenomenon of virtual soldering in the subsequent welding process, and in the welding process, it is necessary to use thicker molten solder and paste to bond the soldering strip and the second grid line 202, so the thicker first The head 232 does not form a raised portion after welding.

In this embodiment, the thickness of the first sub-electrodes 212 decreases gradually along the direction from the first head portion 232 to the first tail portion 242 .

It can be obtained that, in the direction along the direction from the first sub-electrode 212 to the second sub-electrode 222, the section of the first sub-electrode 212 in the direction perpendicular to the back surface of the semiconductor substrate 200 (refer to FIG. 6 ) is an inverted right angle Trapezoidal, the surface of the first sub-electrode 212 is a slope with a smooth transition, which is more conducive to close contact with the welding strip. In other embodiments, the surface of the first sub-electrode may also be a smoothly transitioned curved surface.

In this embodiment, in a direction perpendicular to the back surface of the semiconductor substrate 200 , the difference between the thickness of the first head portion 232 and the thickness of the first tail portion 242 is 1 micron to 3 microns, specifically 2 microns. The difference in thickness between the first head portion 232 and the first tail portion 242 is small, which prevents the first head portion 232 from being too high and lifts up the welding ribbon so that the welding ribbon is not flat while preventing the welding ribbon from being welded.

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

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

Because the welding strip in contact with the second sub-electrode 222 does not warp, the thickness of the second sub-electrode 222 is the same as that of the first tail portion 242, so that the surface of the welding strip after welding is flatter. It can be understood that , the thickness of the second head portion 252 and the thickness of the second tail portion 262 are 7 microns to 11 microns.

FIG. 10 is a schematic cross-sectional view of another second gate line along a direction perpendicular to the surface of the semiconductor substrate according to an embodiment of the present invention.

Referring to FIG. 10 , in other embodiments, the thickness of the first head portion 232 is constant in the direction extending along the second gate line 202 (refer to FIG. 6 ). The first head 232 is a protruding part, which reduces the volume of the sub-electrode and saves the cost while satisfying the requirement of filling the gap formed by the warping of the welding strip and the sub-electrode; The thickness of the solder and the paste is 25 microns to 30 microns, which is much larger than the thickness of the first head 232. After the bonding of the solder and the paste, the protruding first head 232 will not affect the smoothness of the surface of the ribbon Spend.

FIG. 11 is a schematic diagram of the welding effect of the second grid line and the welding ribbon in FIG. 6 .

Referring to FIG. 11 , most of the areas of both ends of the offset soldering strip 203 are still located on the upper surface of the second grid line 202 (refer to FIG. 6 ), which improves the soldering effect of the solar cells.

The following will describe in detail the effect of the solar battery sheet provided by this embodiment after the welding operation with reference to examples.

Table 1 shows the improvement results of the effect after welding the solar cells.

Table I

In an example, the width of the first head 232 and the width of the second tail 262 of the solar cell sheet provided in this 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 Greater than the thickness of the first tail 242, the thickness of the second head 252 and the thickness of the second tail 262; and the width of the first head, the first tail, the second head and the second tail of another solar cell sheet It is the same as the thickness, and the effect after welding is shown in Table 1. Using the solar battery sheet provided in this embodiment, the rework rate of the battery string due to the soldering of the ribbon and welding deviation is 0.2%, while the other solar battery sheet is due to The rework rate of battery strings caused by ribbon virtual welding and welding deviation is 3.2%; using the solar cells provided in this embodiment, the rework rate of photovoltaic modules caused by ribbon virtual welding and welding deviation is 0.04%, and another solar cell The rework rate of the photovoltaic module due to the false welding of the ribbon and the welding deviation is 2.50%; with the solar cell sheet provided in this embodiment, the defect rate of the photovoltaic module due to the virtual welding and welding deviation of the ribbon is 0.001%, and the other The defect rate of photovoltaic modules caused by the weak welding and welding deviation of solar cells is 0.035%.

It can be obtained that the defective rate and rework rate of the solar battery sheet provided in this embodiment are lower than those of another solar battery sheet in various aspects, which improves the welding effect of the solar battery sheet and further improves the performance of the photovoltaic module.

This embodiment provides a solar battery sheet, in the direction in which the first grid lines 201 extend, 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 , during the subsequent soldering process, even if the solder strip 203 on the second grid line 202 is offset, but because the width of the first head 232 and the second tail 262 at both ends of the second grid line 202 are relatively wide, after the offset The two ends of the solder ribbon 203 also have a large contact area with the first head 232 and the second tail 262, which improves the welding effect of the solar cell sheet; meanwhile, in the direction perpendicular to the back of the semiconductor substrate 200, the first head 232 is thicker than the thickness of the first tail portion 242, the thickness of the second head portion 252 and the thickness of the second tail portion 262, because the thickness of the first head portion 232 is greater than the thickness of other regions of the second gate line 202, even if the solder strip 203 is connected with The initial area where the second grid line 202 contacts warps, and the thicker first head 232 can also be in close contact with the solder strip 203 to avoid the phenomenon of virtual soldering in the subsequent soldering process, and in the soldering process It is necessary to use thicker molten solder and paste to bond the solder ribbon 203 and the second grid line 202 , so the thicker first head portion 232 will not form a raised portion after soldering.

Fig. 12 is a schematic structural diagram of a photovoltaic module provided by an embodiment of the present invention.

Referring to FIG. 12 , another embodiment of the present invention also provides a photovoltaic module, including: a plurality of solar cells 301 provided in the above embodiments, and a plurality of solar cells 301 form a battery string 310 through welding ribbons 302 ; The plates are located on opposite sides of the battery string 310 ; the adhesive film layer is located between the battery string 310 and the cover plate.

In this embodiment, the solar battery sheet 301 can be one-half, one-third, one-fourth, one-fifth, or one-sixth slice of the solar battery sheet, and can be cut through the welding ribbon 302 A plurality of sliced solar cells are connected to form a cell string 310 .

Since the solar battery sheet 301 in the photovoltaic module provided by this embodiment is the same as the above-mentioned embodiment, the solar battery sheet 301 in this embodiment includes a first grid line and a second grid line perpendicular to each other, wherein the second grid line It includes a first sub-electrode and a second sub-electrode.

7, 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, the first head 232, the first tail 242, the first The two head portions 252 and the second tail portion 262 are arranged along the extending direction of the second grid line; in the extending direction of the first grid line, the width of the first head portion 232 and the width of the second tail portion 242 are greater than that of the first tail portion 242 width and the width of the second head 252.

In this way, even if the solder strip 302 (referring to FIG. 12 ) on the second grid line in the photovoltaic module is offset, but because the width of the first head 232 and the second tail 262 at both ends of the second grid line are wider, after the offset The two ends of the solder ribbon 302 also have a large contact area with the first head 232 and the second tail 262, which will not form partial welding, improve the welding effect of the solar cells, and further improve the performance of the photovoltaic module.

Referring to FIG. 9 , in this embodiment, the thickness of the first head portion 232 is greater than the thickness of the first tail portion 242 , the thickness of the second head portion 252 and the thickness of the second tail portion 262 .

Since the thickness of the first head portion 232 is greater than the thickness of other areas of the second grid line, even if the initial area where the welding strip 302 (refer to FIG. 12 ) contacts the second grid line warps, the thicker first head portion 232 will It can be in close contact with the solder ribbon 302 to avoid the phenomenon of virtual soldering in the subsequent soldering process, and it is necessary to use thicker molten solder and paste to bond the solder ribbon and the second grid line during the soldering process, so it is relatively The thick first head portion 232 does not form a raised portion after welding.

In this embodiment, the cover plate includes a front plate 305 and a back plate 306. The front plate 305 is a cover plate close to the sun-facing side of the photovoltaic module, and the back plate 306 is a cover plate away from the sun-facing side. The cover plate protects and supports the photovoltaic module. Function; the photovoltaic module also includes: lead wires, which are electrically connected to at least one solar battery sheet 301 in the battery string 310 , and are electrically connected to the junction box through the lead wires.

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 battery string 310, and the second adhesive film layer 304 is located between the back plate 306 and the battery string 310 between.

The material of the adhesive film layer is EVA (Polyethylene vinylacetate, polyethylene-polyvinyl acetate copolymer) adhesive film layer or POE (Polyoxyethylene, polyethylene oxide) adhesive film layer, and the adhesive film layer encapsulates the photovoltaic module to prevent environmental pollution. The water molecules in the battery strings 310 are in contact with each other to prevent power attenuation of the photovoltaic module.

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, other deformation structures and effects can refer to the description of the above embodiment, and will not be repeated here.

The embodiment of the present invention provides a photovoltaic module. For the solar cells 301 in the photovoltaic module, in the direction in which the first grid lines extend, 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 because the width of the first head 232 and the second tail 262 at both ends of the second grid line are relatively wide, the offset The two ends of the moved ribbon 302 also have a larger contact area with the first head 232 and the second tail 262, which improves the welding effect of the solar cell sheet 301, thereby improving the performance of the photovoltaic module; at the same time, the first head 232 The thickness is greater than the thickness of the first tail portion 242, the thickness of the second head portion 252 and the thickness of the second tail portion 262, because the thickness of the first head portion 232 is greater than the thickness of other regions of the second grid line, even if the solder strip 302 is connected to the second grid line The initial area where the grid lines contact is warped, and the thicker first head 232 can also be in close contact with the welding strip 302, so as to avoid the phenomenon of virtual welding in the subsequent welding process, and a relatively thick Thick molten solder and paste bond the solder ribbon 302 and the second grid line, so the thicker first head portion 232 will not form a raised portion after soldering, which will not affect the performance of the photovoltaic module while improving the performance of the photovoltaic module. Photovoltaic modules have other effects.

Those of ordinary skill in the art can understand that the above-mentioned embodiments are specific examples for realizing the present invention, and in practical applications, various changes can be made to it in form and details without departing from the spirit and spirit of the present invention. scope. Any person skilled in the art can make respective alterations and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention should be based on the scope defined in the claims.

Claims (15)

1. A solar cell, characterized in that it comprises: a semiconductor substrate comprising opposing front and rear surfaces; a first gate line, the first gate line is arranged on the back surface of the semiconductor substrate along a first direction; a second gate line, the second gate line is arranged on the back surface of the semiconductor substrate along a second direction, the second gate line is electrically connected to the first gate line, and the first direction is perpendicular to said 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, and the second sub-electrode includes a second head and a second tail, so 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 portion and the width of the second tail portion are greater than the width of the first tail portion and the width of the second head portion; 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 battery sheet according to claim 1 , wherein the thickness of the first sub-electrode gradually decreases in a direction along the direction from the first head to the first tail. 3 . 3. The solar battery sheet according to claim 1, characterized in that, in a direction perpendicular to the back surface of the semiconductor substrate, the difference between the thickness of the first head and the thickness of the first tail is 1 micron to 3 microns. 4. The solar battery sheet according to claim 3, characterized in that, in the direction perpendicular to the back surface of the semiconductor substrate, the thickness of the first head is 9 microns to 13 microns, and the thickness of the first tail is The thickness is 7 microns to 11 microns. 5 . The solar battery sheet according to claim 1 , wherein, 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 battery sheet according to claim 1, characterized in that, in the direction along the first head pointing to the first tail portion, the width of the first sub-electrode gradually decreases; In the direction in which the second head points to the second tail, the width of the second sub-electrode gradually increases. 7 . The solar battery sheet according to claim 1 , wherein, in a direction extending along the second grid line, the width of the first head portion is the same as the width of the second tail portion. 8 . 8. The solar battery sheet according to claim 7, characterized in that, in the direction extending along the second grid line, the length of the first head is 13% to 10% of the length of the first sub-electrode. 17%. 9. The solar battery sheet according to claim 1, characterized in that, in the direction in which the first grid lines extend, the width of the first head is the same as the width of the second tail, and the first The width of a tail is the same as that of the second head. 10 . The solar battery sheet according to claim 9 , wherein 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. 11 . 11. The solar cell according to claim 1, wherein each of the first sub-electrodes and one of the second sub-electrodes adjacent to each other on the second grid line is an electrode group, and each A plurality of the electrode groups are included on the second gate line. 12. The solar cell according to claim 11, wherein the number of the electrode groups is an even number, and every two adjacent electrode groups are arranged symmetrically about the center, wherein each of the electrode groups The first sub-electrode is close to the center of symmetry. 13. The solar cell according to claim 11, wherein the number of the electrode groups is an odd number greater than 1, and every two adjacent electrode groups are arranged symmetrically about the center, wherein each electrode group The first sub-electrode of the 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 is close to the edge of the solar cell. 14. A photovoltaic module, characterized in that it comprises: a plurality of solar cells according to any one of claims 1-13, and a plurality of solar cells form a battery string through welding ribbons; cover plates located on opposite sides of the battery string; An adhesive film layer, the 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 cells are one-half, one-third, one-fourth, one-fifth or sixth of the solar cells One slice of one kind.

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