CELL, PHOTOVOLTAIC MODULE AND METHOD FOR MANUFACTURING PHOTOVOLTAIC MODULE

Abstract

To provide a cell, a photovoltaic module, and a method for manufacturing the photovoltaic module.SOLUTION: A cell includes a substrate, first main grid lines and second main grid lines arranged on the substrate, first fine grid lines connected to the first main grid lines, and second fine grid lines connected to the second main grid lines. The first main grid lines and the second main grid lines have opposite polarities. The first fine grid lines have the same polarity as the first main grid lines, and the second fine grid lines have the same polarity as the second main grid lines. The substrate is provided with main grid pits. At least part of the first main grid lines and at least part of the second main grid lines are located in the main grid pits. Depths of the main grid pits range from 30 μm to 50 μm. Along a thickness direction of the substrate, ratios of the depths of the main grid pits to heights of the first main grid lines and / or the second main grid lines are in the range between 10:3 and 6:5.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present application relates to the technical field of cells, in particular to cells, photovoltaic modules and methods for manufacturing photovoltaic modules. [Background technology]

[0002] 2. Description of the Related Art With the advancement of solar cell technology innovation, the current related battery technology has also undergone significant development, among which back contact type batteries, as a novel solar cell structure, have attracted more and more attention.

[0003] A back-contact battery (IBC) is a battery that has no electrodes on the front surface, and the metal grid lines of the positive and negative electrodes are arranged on the back surface of the battery in a finger-like pattern. The biggest feature of a back-contact battery is that both the PN junction and metal contact are located on the back surface of the battery, and there is no shielding effect of the metal electrode on the front surface, so it has a higher short-circuit current Jsc, and at the same time, the back surface allows wide metal grid lines to reduce the series resistance Rs, improving the fill factor FF, and adding open circuit voltage gain due to the front surface field (FSF) and good passivation effect. This type of battery without shielding on the front surface not only has a higher conversion efficiency, but also looks more beautiful, and the assembly of the full back electrode is easier to assemble.

[0004] Currently, back-contact batteries choose to apply insulating adhesive around the main grid lines to prevent short circuits, which results in poor welding tensile strength for back-contact batteries. Summary of the Invention [Problem to be solved by the invention]

[0005] The present application provides a cell, a photovoltaic module, and a method for manufacturing a photovoltaic module that can improve the welding tensile strength between the cell and the welding strip. [Means for solving the problem]

[0006] A first aspect of the present application provides a cell, the cell including: a substrate; first and second main grid lines provided on the substrate and extending along a first direction; first and second fine grid lines provided on the substrate and extending along a second direction; and main grid pits provided on the substrate; the first main grid lines and the second main grid lines are alternately arranged along a second direction and are of opposite polarity, and the first direction crosses the second direction; the first fine grid lines and the second fine grid lines are alternately arranged along a first direction, the first fine grid lines are connected to the first main grid lines, the second fine grid lines are connected to the second main grid lines, and the first fine grid lines and the first main grid lines have the same polarity, and the second fine grid lines and the second main grid lines have the same polarity; a plurality of main grid pits are spaced apart along the second direction, and at least a portion of the first main grid lines and at least a portion of the second main grid lines are located within the main grid pits; Along the thickness direction of the substrate, the depth h1 of the main grid pit satisfies 30 μm≦h1≦50 μm; Along the thickness direction of the substrate, the ratio range of the depth of the main grid pits to the height of the first main grid lines and / or the second main grid lines is 10:3 to 6:5.

[0007] In some embodiments, the main grid pits extend along the first direction and the first main grid lines and the second main grid lines are disposed within the main grid pits.

[0008] In some embodiments, the plurality of main grid pits are spaced apart along the first direction, and some of the first main grid lines and some of the second main grid lines are located within the main grid pits.

[0009] In some embodiments, the first main grid lines and the second main grid lines have weld points spaced apart along the first direction; The main grid pits include first and second pits spaced apart along a first direction, the first pits and the weld points facing each other along a thickness direction of the substrate, and the depth of the first pits is greater than the depth of the second pits.

[0010] In certain embodiments, the substrate further comprises a plurality of fine grid pits spaced apart along the first direction, at least some of the first fine grid lines and at least some of the second fine grid lines being located within the fine grid pits.

[0011] In some embodiments, the fine grid pits extend along the second direction, and the first fine grid lines and the second fine grid lines are disposed within the fine grid pits.

[0012] In some embodiments, the plurality of fine grid pits are spaced apart along the second direction, and some of the first fine grid lines and some of the second fine grid lines are located within the main grid pits.

[0013] In some embodiments, the depth of the main grid pits is greater than the depth of the fine grid pits along the thickness of the substrate.

[0014] In some embodiments, the depth h2 of the fine grid pits along the thickness direction of the substrate satisfies 25 μm≦h2≦35 μm.

[0015] In some embodiments, when the width of a main grid pit in the second direction is W1 and the width of a fine grid pit in the first direction is W2, W1>W2 is satisfied.

[0016] In some embodiments, the width W1 of the main grid pits along the second direction satisfies 40 μm≦W1≦70 μm and / or the width W2 of the fine grid pits along the first direction satisfies 25 μm≦W2≦35 μm.

[0017] In some embodiments, the cross-sectional shape of the main grid pits along the second direction is rectangular, semicircular, triangular, arcuate, or trapezoidal.

[0018] In some embodiments, the substrate includes a first surface and a second surface disposed opposite each other along a thickness direction of the substrate, the first surface being located on a side of the cell facing sunlight; The first main grid lines, the second main grid lines, the first fine grid lines and the second fine grid lines are all provided on the second surface.

[0019] In some embodiments, the height H1 of the first main grid lines satisfies 15 μm≦H1≦25 μm, and / or the height H2 of the second main grid lines satisfies 15 μm≦H2≦25 μm, and / or the height H3 of the first fine grid lines satisfies 15 μm≦H3≦25 μm, and / or the height H4 of the second fine grid lines satisfies 15 μm≦H4≦25 μm.

[0020] A second aspect of the present application provides a photovoltaic module, the photovoltaic module comprising: A glass, a first sealing adhesive film, a cell string, a second sealing adhesive film and a back plate arranged in order along its thickness direction, the cell string including the cell according to any one of the above claims and a welding strip for connecting adjacent cells; the cells include first cells and second cells alternately distributed along a first direction, and along the first direction, a first main grid line in the first cells and a second main grid line in the second cells are located on a same extension line, and a second main grid line in the first cells and a first main grid line in the second cells are located on a same extension line; The welding strips are connected to the first main grid lines and the second main grid lines in the adjacent cells, respectively, along the thickness direction of the cell, the welding strips are provided on the sides of the first main grid lines and the second main grid lines facing away from the substrate, and at least a portion of the welding strips is located within the main grid pits.

[0021] In certain embodiments, the welding strip includes a body portion and a protrusion, the plurality of protrusions being spaced apart along the first direction, at least a portion of the protrusions being located within the main grid pits.

[0022] In some embodiments, a height h3 of the main body portion along a thickness direction of the cell satisfies 150 μm≦h3≦300 μm; Along the thickness direction of the cell, the height h4 of the protrusions satisfies 35 μm≦h4≦65 μm. In some embodiments, 15% to 25% of the weld strip is located within the main grid pits.

[0023] A third aspect of the present application provides a method for manufacturing a photovoltaic module, the photovoltaic module including a plurality of cells and a welding strip for connecting adjacent cells, The cell includes a substrate, first and second main grid lines on the substrate and extending along a first direction, first and second fine grid lines on the substrate and extending along a second direction, and main grid pits on the substrate, the first direction intersecting a second direction, the main grid pits being spaced apart along the second direction, at least a portion of the first main grid lines and at least a portion of the second main grid lines being located within the main grid pits, a welding strip is connected to the first main grid line and the second main grid line of an adjacent cell, the welding strip is provided along the thickness direction of the cell on the side of the first main grid line and the second main grid line facing away from the substrate, and at least a portion of the welding strip is located within the main grid pit; the substrate includes a first surface and a second surface disposed opposite to each other along a thickness direction of the substrate, the first surface being located on a side of the photovoltaic module facing sunlight, and the first main grid lines, the second main grid lines, the first sub-grid lines, the second sub-grid lines and the welding strips being located on the second surface; The method for manufacturing a photovoltaic module comprises the steps of: Etching main grid pits on a second side of the substrate; performing a doping process on the substrate, and forming n+ doped regions and p+ doped regions arranged alternately with each other after the doping is completed; fabricating a metal electrode on the second surface; placing a welding strip in the cell such that a portion of the welding strip is inserted into the main grid pit; and fastening the weld strip and the cell together by means of a weld point.

[0024] In some embodiments, the substrate further comprises a plurality of fine grid pits spaced apart along the first direction, at least some of the fine grid lines being located within the fine grid pits; The method for manufacturing a photovoltaic module further includes the steps of performing a doping process on the substrate, and after the doping is completed, and before the step of forming the n+ doped region and the p+ doped region alternately arranged with each other, Etching fine grid pits into the second surface. Effect of the Invention

[0025] In the present application, the depth of the main grid pits in the thickness direction of the substrate is 30 μm to 50 μm, and the ratio range of the depth of the main grid pits to the height of the first main grid lines and / or the second main grid lines in the thickness direction of the substrate is 10:3 to 6:5. When the welding strip is connected to the cells, a part of the welding strip can be inserted into the main grid pits, which not only contributes to improving the welding tensile strength between the cells and the welding strip, but also reduces the risk of hidden cracks occurring in the cells and improves the operation stability of the photovoltaic module.

[0026] It is to be understood that the foregoing general description and the following detailed description are merely exemplary and are not restrictive of the present application.

[0027] The drawings herein are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application, and together with the description serve to explain the principles of the present application. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a cross-sectional view of an embodiment of a photovoltaic module according to the present application. [Diagram 2] FIG. 2 is a structural schematic diagram of one embodiment of the cell string in FIG. 1, where two cells are taken as an example. [Diagram 3] 3 is a bottom view of the cell string in FIG. 2 in a third direction. FIG. [Figure 4] FIG. 4 is a structural schematic diagram of an embodiment of the cell in FIG. 3. [Diagram 5] FIG. 5 is a structural schematic diagram of an embodiment of the substrate in FIG. 4. [Figure 6] 5 is a structural schematic diagram of another embodiment of the substrate in FIG. 4. [Figure 7] FIG. 5 is an enlarged view of part I in FIG. [Figure 8] FIG. 3 is a partial cross-sectional view of an embodiment of the cell string in FIG. 2 in the AA direction. [Figure 9] FIG. 9 is an enlarged view of part II in FIG. 8. [Figure 10] 3 is a partial cross-sectional view of another embodiment of the cell string in FIG. 2 in the AA direction. FIG. [Figure 11] FIG. 11 is an enlarged view of part III in FIG. [Figure 12] 11 is a partial cross-sectional view of the cell string in FIG. 10 in the BB direction. [Figure 13] FIG. 13 is an enlarged view of a portion IV in FIG. [Figure 14] 4 is a flowchart of a method for manufacturing a photovoltaic module according to the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] In order to better understand the technical solution of the present application, the following detailed description of the embodiments of the present application is given with reference to the accompanying drawings.

[0030] It is apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. Based on the embodiments of the present application, any other embodiments that a person skilled in the art can think of without any creative effort shall fall within the scope of protection of the present application.

[0031] The terms used in the examples of this application are merely intended to describe particular examples and are not intended to limit the present application. The singular forms "a," "the," and "the" used in the examples of this application and the appended claims are also intended to include the plural forms unless the context requires otherwise.

[0032] The term "and / or" as used herein is only a relational relationship describing related objects, and indicates that three kinds of relations may exist, for example, A and / or B can indicate three kinds of situations: A exists alone, A and B exist simultaneously, and B exists alone. Also, the character " / " in this specification should generally be understood to indicate that the related objects before and after are in an "or" relationship.

[0033] In addition, directional terms such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described in terms of angles shown in the drawings, and should not be understood as limiting the embodiments of the present application. In addition, when the context refers to an element being connected to the "upper" or "lower" of another element, it may not only be directly connected to the "upper" or "lower" of the other element, but also indirectly connected to the "upper" or "lower" of the other element via an intermediate element.

[0034] An embodiment of the present application provides a photovoltaic module, which, as shown in FIG. 1, includes a glass 10, a first sealing adhesive film 20, a cell string 30, a second sealing adhesive film 40 and a back plate 50 arranged in order along its thickness direction, where, as shown in FIG. 2 and FIG. 3, the cell string 30 includes a welding strip 301 and a plurality of cells 302, and the welding strip 301 is used to connect adjacent cells 302. The cell 302 includes two mutually perpendicular first directions X, Y and Z, the first direction X being the width direction of the cell 302, the second direction Y being the length direction of the cell 302, and the third direction Z being the thickness direction of the cell 302, and the multiple cells 302 are distributed at intervals along the first direction X and / or the second direction Y. For convenience of description, in the embodiments of the present application, the cells 302 alternately distributed along the first direction X are referred to as first cells and second cells, respectively, that is, the first cells and the second cells are connected by a welding strip 301.

[0035] Here, the first sealing adhesive film 20 and the second sealing adhesive film 40 can both adopt POE adhesive film, POE is an ethylene octene copolymer, composed of saturated aliphatic chains, has excellent weather resistance, ultraviolet aging resistance, excellent heat resistance, low temperature resistance, and has a wide range of operating temperatures, excellent light transmittance, excellent electrical insulation performance, high cost performance, and easy processing; both can also adopt EVA adhesive film, EVA adhesive film is the most common adhesive film, its main component is ethylene-vinyl acetate copolymer (EVA), and contains small amounts of crosslinking agent, crosslinking assistant, anti-aging agent and other functional assistant; EVA is produced by copolymerization of two kinds of monomers, and is stable due to its short ethylene chain.

[0036] The cell 302 may be a half-cut cell, and the resistance of the cell 302 may be reduced by adopting the half-cut cell, thereby reducing the resistance loss of the photovoltaic module. As shown in FIG. 3 and FIG. 4, the cell 302 includes a substrate 1, and the substrate 1 has a first surface (not shown) and a second surface (not shown) arranged opposite to each other along the third direction Z, the first surface being located on the side of the photovoltaic module facing the sunlight, and the second surface being located on the side of the photovoltaic module away from the sunlight. Here, the substrate 1 may be a silicon substrate, and the silicon substrate may include one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. The substrate 1 may be an N-type semiconductor or a P-type semiconductor, and the present application is not particularly limited to the specific material and type of the substrate 1, and the embodiment of the present application takes the substrate 1 as an N-type silicon substrate as an example.

[0037] The first and / or second surfaces of the substrate 1 are provided with a textured surface (not shown), which has a light trapping effect and can reduce the reflectance of the surface of the substrate 1 to 10% or less, thereby improving the short-circuit current and its conversion efficiency of the cell 302; the second surface is passivated, or the first and second surfaces are passivated to form a passivation layer 7, which has the effect of reducing reflected light and providing surface passivation; and at the same time, a doped layer 8 of different polarity is provided on the second surface, and a PN junction is obtained, for example, by diffusing a boron source and a phosphorus source.

[0038] The first and / or second surface of the substrate 1 are provided with first main grid lines 2 and second main grid lines 3 extending along a first direction X, and first fine grid lines 4 and second fine grid lines 5 extending along a second direction Y on the substrate 1, the first main grid lines 2 and the second main grid lines 3 being alternately arranged along the second direction Y and having opposite polarities, for example, the first main grid line 2 being positive and the second main grid line 3 being negative, or the first main grid line 2 being negative and the second main grid line 3 being positive, the first fine grid lines 4 and the second fine grid lines 5 being alternately arranged along the first direction X, the first fine grid lines 4 being connected to the first main grid lines 2 and the second fine grid lines 5 being connected to the second main grid lines 3, the first fine grid lines 4 and the first main grid lines 2 being of the same polarity, and the second fine grid lines 5 and the second main grid lines 3 being of the same polarity.

[0039] As shown in FIG. 3 , along the first direction X, the first main grid line 2 of the first cell and the second main grid line 3 of the second cell are located on the same extension line, and the second main grid line 3 of the first cell and the first main grid line 2 of the second cell are located on the same extension line, that is, the first main grid line 2 of the first cell and the second main grid line 3 of the adjacent second cell are directly connected by the welding strip 301, and the second main grid line 3 of the first cell and the first main grid line 2 of the adjacent second cell are directly connected by the welding strip 301, which can effectively improve the warpage of the cell 302 and avoid the problem of hidden cracks caused by excessive stress.

[0040] In one embodiment, the first and second sides are both provided with first main grid lines 2, second main grid lines 3, first fine grid lines 4 and second fine grid lines 5, and the welding strips 301 are partly connected to the second sides of the cells 302 and partly bent and extended to connect to the first sides of the adjacent cells 302.

[0041] In another embodiment, as shown in Figs. 2, 3, 8 to 13, the first main grid lines 2, the second main grid lines 3, the first fine grid lines 4, the second fine grid lines 5 and the welding strips 301 are all provided on the second surface, and the photovoltaic module is a back-contact type battery, i.e., the welding strips 301 are respectively connected to the second surfaces of two adjacent cells 302, to reduce the shading of the first main grid lines 2, the second main grid lines 3, the first fine grid lines 4, the second fine grid lines 5 and the welding strips 301 on the first surface, thereby increasing the contact area between the first surface and sunlight, and further improving the photoelectric conversion efficiency of the photovoltaic module.

[0042] This application takes as an example that the first main grid lines 2, the second main grid lines 3, the first fine grid lines 4, the second fine grid lines 5 and the welding strips 301 are all provided on the second surface, that is, the photovoltaic module is an Inverted Battery (IBC).

[0043] Also, the first and second main grid lines 2, 3 do not penetrate the passivation layer 7, i.e., the first and second main grid lines 2, 3 are printed directly on the passivation layer 7, or the first and second main grid lines 2, 3 penetrate the passivation layer 7 and contact the substrate 1. The first and second fine grid lines 4, 5 may also be printed directly on the substrate 1, i.e., the first and second fine grid lines 4, 5 may penetrate the passivation layer 7 and contact the doped layer 8 directly.

[0044] Along the third direction Z, the height H1 of the first main grid lines 2 satisfies 15 μm≦H1≦25 μm, and / or the height H2 of the second main grid lines 3 satisfies 15 μm≦H2≦25 μm, and / or the height H3 of the first fine grid lines 4 satisfies 15 μm≦H3≦25 μm, and / or the height H4 of the second fine grid lines 5 satisfies 15 μm≦H4≦25 μm.

[0045] If the height of the first main grid lines 2 and / or the second main grid lines 3 is less than 15 μm, it is disadvantageous for the first main grid lines 2 and the second main grid lines 3 to collect carriers, which increases the impact on the photoelectric conversion efficiency of the photovoltaic module. If the height of the first main grid lines 2 and / or the second main grid lines 3 is more than 25 μm, it will affect the welding tensile force. Therefore, by making the height of the first main grid lines 2 and the second main grid lines 3 to be 15 μm≦H1≦25 μm and 15 μm≦H2≦25 μm, the first main grid lines 2 and the second main grid lines 3 can contribute to the collection of carriers, which improves the photoelectric conversion efficiency of the photovoltaic module, and at the same time, it is advantageous for the welding tensile force between the cells 302 and the welding strips 301. Specifically, the height of the first main grid lines 2 and / or the second main grid lines 3 can be selected to be 15 μm, 20 μm or 25 μm.

[0046] If the height of the first fine grid lines 4 and / or the second fine grid lines 5 is less than 15 μm, it is disadvantageous for the first fine grid lines 4 and the second fine grid lines 5 to collect carriers, which affects the photoelectric conversion efficiency of the photovoltaic module. If the height of the first fine grid lines 4 and / or the second fine grid lines 5 is greater than 25 μm, it increases the processing cost of the first fine grid lines 4 and the second fine grid lines 5. Therefore, by setting the heights to 15 μm≦H3≦25 μm and 15 μm≦H4≦25 μm, the processing cost of the first fine grid lines 4 and the second fine grid lines 5 can be reduced and the photoelectric conversion efficiency of the photovoltaic module can be improved. Specifically, the height of the first fine grid lines 4 and / or the second fine grid lines 5 can be selected to be 15 μm, 20 μm, or 25 μm.

[0047] The width range of the first main grid lines 2 and / or the second main grid lines 3 along the second direction Y can be selected to be 30 μm to 60 μm, and the width range of the first fine grid lines 4 and / or the second fine grid lines 5 along the first direction X can be selected to be 20 μm to 40 μm, which can reduce the blocking of the effective area of ​​the photovoltaic module by the first main grid lines 2, the second main grid lines 3, the first fine grid lines 4 and the second fine grid lines 5, thereby improving the photoelectric conversion efficiency of the photovoltaic module and reducing the processing costs of the first main grid lines 2, the second main grid lines 3, the first fine grid lines 4 and the second fine grid lines 5, while improving the reliability of the first main grid lines 2 and the second main grid lines 3.

[0048] As shown in Figures 5, 6, 8 to 14, a plurality of main grid pits 11 may be formed in the substrate 1, and the doped layer 8 may be located within the main grid pits 11. The plurality of main grid pits 11 are spaced apart along the second direction Y, and at least a portion of the first main grid lines 2 and at least a portion of the second main grid lines 3 are located within the main grid pits 11 to reduce the distance from the minority carriers to the doped layer 8, thereby improving the open circuit voltage of the cell 302 and further improving the photoelectric conversion efficiency of the photovoltaic module.

[0049] When the welding strip 301 is connected to an adjacent cell 302, at least a portion of the welding strip 301 is located within the main grid pit 11, which contributes to improving the welding tensile force between the cell 302 and the welding strip 301, and improves the connection stability between the welding strip 301 and the cell 302.

[0050] Specifically, the first thin grid lines 4 do not come into contact with the second main grid lines 3 having a different polarity, and therefore the first thin grid lines 4 do not need to enter the main grid line pits 11 in which the second main grid lines 3 are printed, and the first thin grid lines 4 come into contact with the first main grid lines 2 having the same polarity, and therefore the first thin grid lines 4 can enter the main grid line pits 11 in which the first main grid lines 2 are printed and connect with the first main grid lines 2. The second thin grid lines 5 do not come into contact with the first main grid lines 2 having a different polarity, and therefore the second thin grid lines 5 do not need to enter the main grid line pits 11 in which the first main grid lines 2 are printed, and however the second thin grid lines 5 come into contact with the second main grid lines 3 having the same polarity, and therefore the second thin grid lines 5 can enter the main grid line pits 11 in which the second main grid lines 3 are printed and connect with the second main grid lines 3.

[0051] Along the third direction Z, the thickness H of the substrate 1 satisfies 160 μm≦H≦230 μm, and specifically, the thickness of the substrate 1 in the third direction Z may be 160 μm, 179 μm, 186 μm, 200 μm, 226 μm, or 230 μm.

[0052] In this embodiment, since the main grid pits 11 are provided on the substrate 1, if the thickness of the substrate 1 is small, i.e., H<160 μm, the substrate 1 is prone to the risk of hidden cracks near the main grid pits 11. If the thickness of the substrate 1 is large, i.e., H>230 μm, the cost of the cells 302 will increase and the overall thickness of the photovoltaic module will increase. Therefore, by making 160 μm≦H≦230 μm, the overall thickness of the photovoltaic module can be reduced to reduce the manufacturing cost, and at the same time, the structural strength of the substrate 1 can be increased, the service life of the photovoltaic module can be extended, and the operation stability of the photovoltaic module can be improved.

[0053] Along the third direction Z, the depth h1 of the main grid pits 11 satisfies 30 μm≦h1≦50 μm.

[0054] In this embodiment, if the depth of the main grid pits 11 is less than 30 μm, it is disadvantageous to the welding tensile strength between the cells 302 and the welding strip 301, and if the depth of the main grid pits 11 is more than 50 μm, it increases the risk of hidden cracks occurring in the cells 302. Therefore, by making the depth 30 μm≦h1≦50 μm, it is possible to reduce the risk of hidden cracks occurring in the cells 302 and also to contribute to improving the welding tensile strength between the welding strip 301 and the cells 302. Specifically, the depth of the main grid pits 11 may be 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm.

[0055] Along the third direction Z, the ratio range of the depth of the main grid pits 11 to the height of the first main grid lines 2 is 10:3 to 6:5 and / or the ratio range of the depth of the main grid pits 11 to the height of the second main grid lines 3 is 10:3 to 6:5.

[0056] The broad range of the ratio between the depth of the main grid pits 11 and the height of the first main grid lines 2 may be 10:1 to 10:9, the narrow range may be 5:2 to 5:3, in particular along the third direction Z the broad range of the ratio between the depth of the main grid pits 11 and the height of the first main grid lines 2 is 10:3 to 6:5, for example 10:3, 2:1, 7:3, 9:4, 5:2 or 6:5; and / or the broad range of the ratio between the depth of the main grid pits 11 and the height of the second main grid lines 3 may be 10:1 to 10:9, the narrow range may be 5:2 to 5:3, in particular along the third direction Z the broad range of the ratio between the depth of the main grid pits 11 and the height of the second main grid lines 3 is 10:3 to 6:5, for example 2:1, 7:3, 9:4, 5:2 or 6:5. Here, the ratio between the depth of the main grid pits 11 and the height of the first main grid lines 2, and the ratio between the depth of the main grid pits 11 and the height of the second main grid lines 3 may be the same or different.

[0057] In this embodiment, the depth of the main grid pits 11 in the third direction Z is 30 μm-50 μm, and the ratio of the depth of the main grid pits 11 to the height of the first main grid lines 2 and / or the second main grid lines 3 in the third direction Z is 10:3-6:5, which not only contributes to improving the welding tensile strength between the cells 302 and the welding points 6, but also reduces the risk of hidden cracks in the cells 302. At the same time, the distance from the minority carriers to the doped layers 8 is reduced, thereby improving the open circuit voltage of the back-contact battery and improving the photoelectric conversion efficiency of the IBC.

[0058] The cross-sectional shape of the main grid pits 11 in the second direction Y may be rectangular, semicircular, triangular, arc-shaped, trapezoidal, or other modified structure. The embodiments of the present application are not particularly limited to the cross-sectional shape of the main grid pits 11. In the embodiments of the present application, the cross-sectional shape of the main grid pits 11 in the second direction Y is taken as an example to be semicircular.

[0059] 4 , the first main grid line 2 and the second main grid line 3 are both provided with welding points 6 spaced apart along the first direction X, and the welding strips 301 and the cells 302 are fixedly connected by the welding points 6. Here, the number of welding points 6 on one first main grid line 2 and one second main grid line 3 is three or more, and specifically, the number of welding points 6 may be four or more, for example, five or six, and the embodiment of the present application is not particularly limited to the specific number of welding points 6.

[0060] In one embodiment, as shown in Figures 4 and 5, the main grid pits 11 extend along the first direction X, and the first main grid line 2 and the second main grid line 3 are entirely disposed within the main grid pits 11, and the welding strips 301 are directly engaged within the main grid pits 11 and connected to the first main grid line 2 and the second main grid line 3, as shown in Figures 8 and 9. The main grid pits 11 extend along the first direction X, which simplifies the processing steps of the main grid pits 11 and reduces the processing costs of the main grid pits 11. The entire welding strip 301 is locked in the main grid pit 11. When the welding strip 301 moves relative to the cell 302, the welding strip 301 abuts against the side wall of the main grid pit 11, restricting the installation position of the welding strip 301, reducing the difficulty of installing the welding strip 301, increasing the stability of the connection between the welding strip 301 and the cell 302, and reducing the risk of the welding strip 301 tilting. Taking the welding strip 301 on the first main grid line 2 as an example, the risk of contact or electrical connection between the welding strip 301 and the second fine grid line 5 can be reduced, that is, the risk of the first fine grid line 4 and the second fine grid line 5 being connected in series via the first main grid line 2 and the welding strip 301, reducing the risk of the cell 302 being short-circuited, and improving the operation stability and service life of the cell 302.

[0061] 4 and 6, a plurality of main grid pits 11 are spaced apart along the first direction X, and a portion of the first main grid lines 2 and a portion of the second main grid lines 3 are located within the main grid pits 11. The main grid pits 11 are spaced apart along the first direction X, which contributes to reducing the etching area of ​​the substrate 1 and thereby improving the structural strength of the substrate 1. Specifically, as shown in FIGS. 10 to 13 , the welding strip 301 includes a body portion 301 a and a protrusion portion 301 b, and at least a portion of the protrusion portion 301 b is located within the main grid pit 11. When the welding strip 301 moves relative to the cell 302, the protrusion portion 301 b abuts against the side wall of the main grid pit 11 to limit the attachment position of the welding strip 301. The first fine grid line 4 and the second fine grid line 5 are connected in series via the first main grid line 2 and the welding strip 301, reducing the risk of the cell 302 being short-circuited, and improving the operational stability and service life of the cell 302.

[0062] In this embodiment, the number of the main grid pits 11 is equal to or greater than the number of the protrusions 301b, which contributes to adjusting the installation position of the welding strip 301 during the installation process. In addition, the cross-sectional contour shape of the protrusions 301b is not limited to a rectangular, cylindrical, conical, spherical, etc., and the embodiment of the present application is not particularly limited to the contour shape of the protrusions 301b.

[0063] Specifically, the main grid pits 11 include a first pit (not shown) and a second pit (not shown) spaced apart along a first direction X, the first pit and the weld point 6 face each other along a third direction Z, and the depth of the first pit is greater than the depth of the second pit.

[0064] In this embodiment, the welding points 6 are located at the first pits, and the depth of the first pits is greater than the depth of the second pits, so that after the welding strip 301 is connected to the cells 302, the welding strip 301 protrudes at the welding points 6, which reduces the risk of the surface of the welding strip 301 that is separated from the cells 302 becoming uneven, which is beneficial to the installation and use of the photovoltaic module. By providing shallow second pits in the non-welding point area, the number of protrusions 301b and main grid pits 11 can be increased, thereby increasing the number of engagement positions between the welding strip 301 and the cells 302, reducing the risk of short-circuiting the cells 302 due to local deformation of the welding strip 301, and further improving the operation stability and service life of the cells 302.

[0065] Here, one or more second pits may be provided between two adjacent first pits, and one or more first pits may be provided between two adjacent second pits, and the present application is not particularly limited to the specific distribution manner of the first pits and the second pits. The contour shapes of the first pits and the second pits may be the same or different, and the present application is not particularly limited to the specific structure of the first pits and the second pits.

[0066] Furthermore, the cross-sectional shape of the main body portion 301a includes, but is not limited to, a square, a circle, or other modified structures, and the present application is not particularly limited with respect to the specific structure of the main body portion 301a.

[0067] The thickness dimension h3 of the main body 301a in the third direction Z satisfies 0.1 mm≦h3≦0.3 mm, and specifically, the thickness of the main body 301a in the third direction Z may be 0.1 mm, 0.15 mm, 0.21 mm, 0.26 mm, or 0.3 mm.

[0068] In this embodiment, if the thickness of the body 301a is small, that is, h3<0.1mm, there is a risk that the welding strip 301 will be cracked during processing, transportation and installation, and at the same time, there is a risk that the device cannot weld the welding strip 301 to the welding point 6. If the thickness of the body 301a is large, that is, h3>0.3mm, the welding strip 301 is easily displaced from the preset installation position due to the action of external force, that is, the stress of the welding strip 301 is large, and at the same time, the cost of the welding strip 301 is increased. Therefore, by making 0.1mm≦h3≦0.3mm, it is easy for the device to weld the welding strip 301 to the welding strip 301, the cost of the welding strip 301 can be reduced, the structural strength of the body 301a can be improved, the service life of the welding strip 301 can be extended, and the operation stability of the welding strip 301 can be improved, and at the same time, the stress of the welding strip 301 can be reduced and the welding stability can be improved.

[0069] The height h4 of the protrusion 301b in the third direction Z satisfies 35 μm≦h4≦65 μm, and / or the depth h1 of the main grid pit 11 in the third direction Z satisfies 35 μm≦h1≦45 μm. Specifically, the height of the protrusion 301b in the third direction Z may be 35 μm, 42 μm, 51 μm, or 65 μm. The depth of the main grid pit 11 in the third direction Z may be 35 μm, 39 μm, 43 μm, or 45 μm.

[0070] In a high temperature environment, the welding strip 301 expands due to thermal expansion and cold contraction, and if the height of the protrusion 301b is large, i.e., h4>65 μm, the protrusion 301b will apply a force to the cell 302, resulting in damage to the cell 302. If the height of the protrusion 301b is small, i.e., h4<35 μm, the connection depth between the protrusion 301b and the main grid pit 11 will be small, and there is a risk that oxygen will enter the gap between the protrusion 301b and the main grid pit 11 during the installation and fixing process, causing the cell 302 to be oxidized. Therefore, by making 35 μm≦h4≦65 μm, the risk of the welding strip 301 damaging the cell 302 can be reduced, and at the same time, the risk of the cell 302 being oxidized can be reduced, thereby extending the service life of the cell 302 and improving the operation stability of the cell 302.

[0071] If the depth of the main grid pits 11 is small, i.e., h1<35 μm, there is a risk that the protrusions 301b will come off the main grid pits 11. If the depth of the main grid pits 11 is large, i.e., h1>45 μm, the strength of the substrate 1 will be reduced, and there is a risk that the substrate 1 will be damaged during subsequent processing, transportation, and use of the substrate 1. Therefore, by making 35 μm≦h1≦45 μm, the connection stability between the protrusions 301b and the main grid pits 11 can be improved, and the accuracy of the mounting position of the welding strip 301 can be further improved, while at the same time, the risk of defects such as hidden cracks occurring in the cells 302 can be reduced, thereby extending the service life of the cells 302 and improving the operation stability of the cells 302.

[0072] In any of the above embodiments, 15% to 25% of the welding strip 301 is in the main grid pit 11. If the portion of the welding strip 301 in the main grid pit 11 is less than 15%, the contact area between the welding strip 301 and the main grid pit 11 is too small, and the welding tensile force is not ideal. If the portion of the welding strip 301 in the main grid pit 11 is more than 25%, hidden cracks in the cells 302 are likely to occur. Therefore, by making 15% to 25% of the welding strip 301 in the grid pit, it is possible to avoid the contact area between the welding strip 301 and the main grid pit 11 being too small, and it is also possible to increase the welding tensile force between the cells 302 and the welding strip 301, thereby reducing the rate of hidden crack occurrence in the cells 302.

[0073] 4 to 7, the substrate 1 further includes a plurality of fine grid pits 12 spaced apart along the first direction X, and at least a portion of the first fine grid lines 4 and at least a portion of the second fine grid lines 5 are located within the fine grid pits 12. Since the first surface of the substrate 1 does not have grid lines, the photo-generated electrons on the first surface need to be collected by the grid lines (the first fine grid lines 4, the second fine grid lines 5, the first main grid lines 2 and / or the second main grid lines 3) on the second surface. The fine grid pits 12 can reduce the path of the photo-generated electrons to a certain extent, reduce cross-combination, and improve the photoelectric conversion efficiency of the cell 302.

[0074] In one embodiment, the fine grid pits 12 extend along the second direction Y, and the entire first fine grid lines 4 and the entire second fine grid lines 5 are disposed within the fine grid pits 12. The fine grid pits 12 extend along the second direction Y, which simplifies the processing steps for the fine grid pits 12 and reduces the processing costs for the fine grid pits 12.

[0075] In another embodiment, the fine grid pits 12 are spaced apart along the second direction Y, and some of the first fine grid lines 4 and some of the second fine grid lines 5 are located within the main grid pits 11. The fine grid pits 12 are spaced apart along the second direction Y, which contributes to reducing the etched area of ​​the substrate 1 and thereby improving the structural strength of the substrate 1.

[0076] Specifically, along the third direction Z, the depth of the main grid pits 11 is greater than the depth of the fine grid pits 12, which contributes to fitting some of the welding strips 301 into the main grid pits 11, and can further increase the welding tensile force.

[0077] Along the third direction Z, the depth h2 of the fine grid pits 12 satisfies 25 μm≦h2≦35 μm.

[0078] In this embodiment, if the depth of the fine grid pits 12 is less than 25 μm, the fine grid pits 12 cannot be formed, and the efficiency of the cells 302 cannot be improved. If the depth of the fine grid pits 12 is greater than 35 μm, the substrate 1 is excessively thinned, resulting in an increase in the rate of hidden cracks. Therefore, by making 25 μm≦h2≦35 μm, it is possible to not only reduce the rate of hidden cracks in the cells 302, but also to contribute to the formation of the fine grid pits 12. Specifically, the depth of the fine grid pits 12 can be selected to be 25 μm, 28 μm, 31 μm, or 35 μm.

[0079] The width of the main grid pit 11 along the second direction is W1, and the width of the fine grid pit 12 along the first direction is W2, where W1>W2. The width of the main grid pit 11 along the second direction Y is greater than the width of the fine grid pit 12 along the first direction X, which can more effectively increase the welding tensile force, i.e., to allow some welding strips 301 to fit into the main grid pit 11, both the width and depth of the main grid pit 11 are greater than the width and depth of the fine grid pit 12, thereby reducing the risk of the welding strips 301 being erroneously installed in the fine grid pit 12.

[0080] The width W1 of the main grid pits 11 in the second direction satisfies 40 μm≦W1≦70 μm, and / or the width W2 of the fine grid pits 12 in the first direction satisfies 25 μm≦W2≦35 μm.

[0081] If the width of the main grid pits 11 is smaller than 40 μm, it is disadvantageous in improving the welding tensile strength, and if the width of the main grid pits 11 is larger than 70 μm, it increases the risk of hidden cracks occurring in the cells 302. Therefore, by making the width of the main grid pits 11 40 μm≦W1≦70 μm, it is possible to not only contribute to the welding tensile strength but also reduce the risk of hidden cracks occurring in the cells 302. Specifically, the width of the main grid pits 11 can be selected to be 40 μm, 50 μm, 60 μm, or 70 μm.

[0082] If the width of the fine grid pits 12 along the first direction X is less than 25 μm, it will not improve the efficiency of the cells 302, and if the width of the fine grid pits 12 along the first direction X is greater than 35 μm, it will increase the rate of hidden cracks in the cells 302. Therefore, by making W2 25 μm≦W2≦35 μm, it is possible to not only improve the efficiency of the cells 302 but also reduce the rate of hidden cracks in the cells 302. Specifically, the width of the fine grid pits 12 can be selected to be 25 μm, 28 μm, 31 μm, or 35 μm.

[0083] Based on the photovoltaic module in any of the above embodiments, taking a back-contact type cell as an example, the present application provides a method for manufacturing a photovoltaic module, as shown in FIG. 14, the method for manufacturing a photovoltaic module includes: Etching main grid pits 11 on the second side of the substrate 1; performing a doping process on the substrate 1, and forming n+ doped regions and p+ doped regions arranged alternately with each other after the doping is completed; fabricating a metal electrode on the second side, the metal electrode including first main grid lines 2, second main grid lines 3, first fine grid lines 4, second fine grid lines 5 and welds 6, the first fine grid lines 4 and the second fine grid lines 5 being in ohmic contact with the n+ doped regions and the p+ doped regions, and at least a portion of the first main grid lines 2 and the second main grid lines 3 being located within the main grid pits 11; placing a welding strip 301 in the cell 302 such that a portion of the welding strip 301 is inserted into the main grid pit 11; and fastening the welding strip 301 and the cell 302 by means of the welding points 6.

[0084] Specifically, the method for manufacturing a photovoltaic module includes performing a doping process on the substrate 1, and after the doping is completed, and before the step of forming the n+ doped regions and the p+ doped regions alternately arranged with each other, Further included is the step of etching fine grid pits 12 into the second surface.

[0085] In summary, the method for manufacturing a photovoltaic module according to an embodiment of the present application is specifically as follows. Main grid pits 11 and fine grid pits 12 are etched into the second surface of the substrate 1 by laser etching or mechanical etching methods. The substrate 1 is cleaned to remove post-etch damaged structures. A texturing process is performed on the first and second surfaces of the substrate 1 to form a textured surface. The purpose of the texturing is to create a bumpy structure on the originally bright surface of the substrate 1 through a chemical reaction, thereby extending the propagation path of light on that surface and improving the light absorption of the cell 302. A doping process is performed on the second surface of the substrate 1, and after the doping is completed, a doped layer 8 is formed, which includes n+ doped regions and p+ doped regions arranged alternately with each other, and a PN junction is obtained, for example, by diffusing a boron source and a phosphorus source. A PECVD (Plasma Enhanced Chemical Vapor Deposition) device is used to coat the first surface of the substrate 1 to form an anti-reflection film, which can reduce the reflection of light. A layer of SiNx (silicon nitride) is deposited on the second surface of the substrate 1 using a PECVD apparatus to form a passivation layer 7, which has the functions of surface passivation and anti-reflection. A metal electrode is fabricated on the second side of the substrate 1, where the metal electrode includes first main grid lines 2, second main grid lines 3, first fine grid lines 4, second fine grid lines 5 and welds 6, where the first fine grid lines 4 and the second fine grid lines 5 are in ohmic contact with the n+ doped regions and p+ doped regions of the second side, where at least a portion of the first main grid lines 2 and at least a portion of the second main grid lines 3 are located within the main grid pits 11, and where at least a portion of the first fine grid lines 4 and at least a portion of the second fine grid lines 5 are located within the fine grid pits 12. The welding strip 301 is placed in the cell 302 so that a portion of the welding strip 301 is inserted into the main grid pit 11 . The welding strip 301 and the cell 302 are welded to the welding point 6 to form the cell string 30 . The fixing glass 10, the first sealing adhesive film 20, the cell string 30, the second sealing adhesive film 40 and the back plate 50 are laminated.

[0086] Here, the metal electrodes can be manufactured by, specifically, printing silver-aluminum paste on the p+ doped region of the second surface after the processing by the method of screen printing, and printing silver paste on the n+ doped region of the second surface. The first main grid lines 2, the second main grid lines 3 and the welding points 6 can be printed directly on the passivation layer 7 of the second surface, and do not penetrate the substrate 1. Alternatively, the first main grid lines 2, the second main grid lines 3, the first fine grid lines 4 and the second fine grid lines 5 can be printed on the doped layer 8 through the passivation layer 7, and then sintering process can be performed.

[0087] In this embodiment, by utilizing the formed main grid pits 11 and fine grid pits 12, the welding tensile strength between the cells 302 and the welding strip 301 can be improved, and the distance from the minority carriers to the doped layer 8 can be greatly reduced, thereby improving the open circuit voltage of the back-contact type battery.

[0088] The above is only a preferred embodiment of the present application, and does not limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application. [Explanation of symbols]

[0089] 10-Glass 20-First sealing adhesive film 30-cell string 301-Welded Strip 301a-Main body 301b-protrusion 302-Cell 40-Second sealing adhesive film 50-Backplate 1-Substrate 11-Main Grid Pit 12-fine grid pits 2-1st main grid line 3-Second main grid line 4-First thin grid line 5-Second thin grid line 6- Welding point 7- Passivation Layer 8-Doped layer

Claims

1. A cell (302) comprising: a substrate (1); first main grid lines (2) and second main grid lines (3) arranged on the substrate (1) and extending along a first direction (X); first fine grid lines (4) and second fine grid lines (5) arranged on the substrate (1) and extending along the second direction (Y); and main grid pits (11) arranged on the substrate (1); the first main grid lines (2) and the second main grid lines (3) are alternately arranged along a second direction (Y) and have opposite polarities, and the first direction (X) intersects with the second direction (Y); the first thin grid lines (4) and the second thin grid lines (5) are alternately arranged along the first direction (X), the first thin grid lines (4) are connected to the first main grid lines (2), the second thin grid lines (5) are connected to the second main grid lines (3), and the first thin grid lines (4) and the first main grid lines (2) have the same polarity, and the second thin grid lines (5) and the second main grid lines (3) have the same polarity; a plurality of the main grid pits (11) are spaced apart along the second direction (Y), and at least a portion of the first main grid line (2) and at least a portion of the second main grid line (3) are located within the main grid pits (11); a plurality of said main grid pits (11) are distributed at intervals along said first direction (X), and a portion of said first main grid line (2) and a portion of said second main grid line (3) are located within said main grid pits (11).

2. The first main grid lines (2) and the second main grid lines (3) have welding points (6) spaced apart along the first direction (X), 2. The cell of claim 1, wherein the main grid pits (11) include first and second pits spaced apart along the first direction (X), the first pits and the weld points (6) are opposed along a thickness direction of the substrate (1), and a depth of the first pits is greater than a depth of the second pits.

3. 2. The cell according to claim 1, characterized in that the substrate (1) further comprises a plurality of fine grid pits (12) distributed at intervals along the first direction (X), and at least a portion of the first fine grid lines (4) and at least a portion of the second fine grid lines (5) are located within the fine grid pits (12).

4. 4. The cell according to claim 3, characterized in that the fine grid pits (12) extend along the second direction (Y), the first fine grid lines (4) and the second fine grid lines (5) being disposed within the fine grid pits (12).

5. 4. The cell of claim 3, wherein a plurality of the fine grid pits (12) are distributed at intervals along the second direction (Y), and a portion of the first fine grid lines (4) and a portion of the second fine grid lines (5) are located within the main grid pits (11).

6. 4. The cell according to claim 3, characterized in that along the thickness of the substrate (1), the depth of the main grid pits (11) is greater than the depth of the fine grid pits (12).

7. 7. The cell according to claim 6, characterized in that the depth h2 of the fine grid pits (12) along the thickness direction of the substrate (1) satisfies 25 μm≦h2≦35 μm.

8. 4. The cell of claim 3, wherein W1 > W2 is a width of the main grid pits (11) along the second direction (Y) and W2 is a width of the fine grid pits (12) along the first direction (X).

9. 9. The cell according to claim 8, characterized in that a width W1 of the main grid pits (11) along the second direction (Y) satisfies 40 μm≦W1≦70 μm and / or a width W2 of the fine grid pits (12) along the first direction (X) satisfies 25 μm≦W2≦35 μm.

10. The cell according to any one of claims 1 to 9, characterized in that the cross-sectional shape of the main grid pit (11) along the second direction (Y) is rectangular, semicircular, triangular, arcuate or trapezoidal.

11. The substrate (1) includes a first surface and a second surface that are provided opposite to each other along a thickness direction of the substrate (1), and the first surface is located on a side of the cell (302) facing sunlight; 10. The cell according to claim 1, wherein the first main grid line (2), the second main grid line (3), the first fine grid line (4) and the second fine grid line (5) are all provided on the second face.

12. 10. The cell according to claim 1, characterized in that the height H1 of the first main grid lines (2) satisfies 15 μm≦H1≦25 μm and / or the height H2 of the second main grid lines (3) satisfies 15 μm≦H2≦25 μm and / or the height H3 of the first fine grid lines (4) satisfies 15 μm≦H3≦25 μm and / or the height H4 of the second fine grid lines (5) satisfies 15 μm≦H4≦25 μm.

13. 1. A photovoltaic module comprising: The photovoltaic module includes a glass (10), a first sealing adhesive film (20), a cell string (30), a second sealing adhesive film (40), and a back plate (50) arranged in order along its thickness direction, the cell string (30) includes a plurality of cells (302) according to claim 1 and a welding strip (301) for connecting adjacent cells (302); the cells (302) include first cells and second cells alternately distributed along the first direction (X), the first main grid line (2) in the first cells and the second main grid line (3) in the second cells are positioned on a common extension line along the first direction (X), and the second main grid line (3) in the first cells and the first main grid line (2) in the second cells are positioned on a common extension line along the first direction (X); 1. A photovoltaic module comprising: a photovoltaic module including a first main grid line and a second main grid line, the first main grid line and the second main grid line being electrically connected to each other; a first main grid line and a second main grid line being electrically connected to each other; a first main grid line and a second main grid line being electrically connected to each other;

14. 14. The photovoltaic module of claim 13, wherein the welding strip (301) comprises a body portion (301a) and a protrusion portion (301b), the protrusion portions (301b) being spaced apart along the first direction (X), and at least a portion of the protrusion portion (301b) being located within the main grid pit (11).

15. Along the thickness direction of the cell (302), the height h3 of the main body portion (301a) satisfies 150 μm≦h3≦300 μm; 15. The photovoltaic module according to claim 14, wherein a height h4 of the protrusion (301b) along a thickness direction of the cell (302) satisfies 35 μm≦h4≦65 μm.

16. The photovoltaic module of claim 13, characterized in that 15% to 25% of the welding strip (301) is within the main grid pits (11).

17. A method for manufacturing a photovoltaic module, the photovoltaic module comprising a plurality of cells according to claim 2 and a welding strip (301) for connecting adjacent cells (302), the welding strips (301) are connected to the first main grid line (2) and the second main grid line (3) of the adjacent cell (302), respectively, the welding strips (301) are provided on the sides of the first main grid line (2) and the second main grid line (3) that are remote from the substrate (1) along the thickness direction of the cell (302), and at least a part of the welding strips (301) is located within the main grid pits (11); the substrate (1) includes a first surface and a second surface that are arranged opposite to each other along a thickness direction of the substrate, the first surface being located on a side of the photovoltaic module facing sunlight, and the first main grid lines (2), the second main grid lines (3), the first fine grid lines (4), the second fine grid lines (5) and the welding strips (301) being all located on the second surface; The method for manufacturing the photovoltaic module includes the steps of: Etching the main grid pits (11) on the second side of the substrate (1); performing a doping process on the substrate (1) to form n+ doped regions and p+ doped regions arranged alternately after the doping is completed; fabricating a metal electrode on the second surface; placing said welding strip (301) in said cell (302) such that a portion of said welding strip (301) is inserted into said main grid pit (11); and fixing said welding strip (301) and said cells (302) by said welding points (6).

18. The substrate (1) further includes a plurality of fine grid pits (12) spaced apart along the first direction (X), and at least a portion of the first fine grid lines (4) and at least a portion of the second fine grid lines (5) are located within the fine grid pits (12); The method for manufacturing the photovoltaic module further comprises the steps of performing a doping process on the substrate (1), and after the doping is completed, and before the step of forming the n+ doped regions and the p+ doped regions alternately arranged with each other, 20. The method of claim 17, further comprising the step of etching said fine grid pits (12) on said second surface.

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