Solar cell and printing screen assembly and photovoltaic assembly thereof

Abstract

The utility model relates to the technical field of solar cells, in particular to a solar cell, a printing screen assembly thereof and a photovoltaic assembly. The solar cell comprises a substrate, a plurality of bus grid lines and a plurality of collector grid lines. The bus grid lines are arranged on the surface of the substrate, and the extension direction of the bus grid lines on the surface of the substrate is a first direction. The collector grid lines are arranged on the surface of the substrate and extend in the second direction, and the second direction intersects with the first direction. The two collector grid lines are arranged in the second direction to form a pair. In each pair of collector grid lines, the two collector grid lines are staggered in the first direction and the second direction, and in the second direction, the ends, close to each other, of the two collector grid lines are provided with connecting sections. The two connecting sections of at least one pair of collector grid lines are in lap joint with the bus grid lines, and at least one connecting section penetrates through the bus grid lines in the second direction. According to the solar cell, the connection section is arranged to provide a margin for alignment offset of the solder strip.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a solar cell, a printing screen assembly of the solar cell and a photovoltaic module. BACKGROUND

[0002] The conversion efficiency of solar cells still has room for further improvement. One of the directions for improving the conversion efficiency of solar cells in the current photovoltaic industry is to focus on the optimization of electrode grid line patterns. However, how to further optimize the design of electrode patterns based on the current industrial process capability is a problem that needs to be solved by those skilled in the art. CONTENT OF THE UTILITY MODEL

[0003] The embodiments of the present application disclose a solar cell, a printing screen assembly of the solar cell and a photovoltaic module, which can make the printing screen have good structural strength and reduce the phenomenon of printing deviation and thick grid lines, and provide a margin for electrode alignment deviation by setting the connecting section as a solder strip.

[0004] To achieve the above-mentioned purpose, in a first aspect, the embodiments of the present application disclose a solar cell, comprising:

[0005] a substrate;

[0006] a plurality of bus grid lines, each of the bus grid lines is arranged on the surface of the substrate, and the extension direction of the bus grid line on the surface of the substrate is a first direction; and

[0007] a plurality of current collecting grid lines, each of the current collecting grid lines is arranged on the surface of the substrate and extends along a second direction, the second direction intersects the first direction; two of the current collecting grid lines are arranged in a pair in the second direction; in each pair of the current collecting grid lines, the two current collecting grid lines are arranged staggered in the first direction and the second direction, and in the second direction, each of the two current collecting grid lines has a connecting section at an end close to each other;

[0008] wherein, the two connecting sections of at least one pair of the current collecting grid lines are overlapped on the bus grid line, and at least one of the connecting sections passes through the bus grid line in the second direction.

[0009] In a possible implementation manner of the first aspect, the solar cell further comprises an interconnection grid line, the interconnection grid line extends along the first direction, and the interconnection grid line is arranged spaced apart from the bus grid line in the second direction.

[0010] In the second direction, among the three current collecting grid lines, a first current collecting grid line and a second current collecting grid line form a pair of current collecting grid lines, and the second current collecting grid line and a third current collecting grid line form another pair of current collecting grid lines, wherein the two connecting sections of the pair of current collecting grid lines are overlapped on the bus grid line, and the two connecting sections of the other pair of current collecting grid lines are overlapped on the interconnection grid line;

[0011] The bus grid line is configured to collect current in the current collecting grid line, and the interconnection grid line is configured to conduct current on the current collecting grid line to another current collecting grid line.

[0012] In a possible implementation of the first aspect, the width of the bus grid line is greater than the width of the interconnection grid line.

[0013] In a possible implementation of the first aspect, the width of the bus grid line is 25 μm to 100 μm, and the width of the interconnection grid line is 20 μm to 50 μm.

[0014] In a possible implementation of the first aspect, a plurality of the current collecting grid lines are arranged in a column along the first direction, and a plurality of columns of the current collecting grid lines are arranged along the second direction, and two adjacent columns of the current collecting grid lines are overlapped on the same bus grid line or the same interconnection grid line.

[0015] In the two adjacent columns of the current collecting grid lines, one column of the current collecting grid lines is a first side grid line, and the other column of the current collecting grid lines is a second side grid line; in the first direction, the first side grid line and the second side grid line are alternately arranged, and any first side grid line and an adjacent second side grid line form a pair of current collecting grid lines.

[0016] In a possible implementation of the first aspect, in the second direction, the bus grid line and the interconnection grid line are alternately arranged, and an Nth column of the current collecting grid lines and an (N+1)th column of the current collecting grid lines are overlapped on the same interconnection grid line; wherein N is a positive integer.

[0017] The (N+1)th column of the current collecting grid lines and an (N+2)th column of the current collecting grid lines are overlapped on the same bus grid line.

[0018] And / or, the Nth column of the current collecting grid lines and an (N-1)th column of the current collecting grid lines are overlapped on the same bus grid line.

[0019] In a possible implementation of the first aspect, the pitch between each bus grid line and an adjacent interconnection grid line is equal.

[0020] And / or, in the same column of the current collecting grid lines, a plurality of the current collecting grid lines are equidistantly arranged.

[0021] And / or, in the first direction, the pitch between each of the first side gate lines and the adjacent second side gate lines in the two adjacent columns of the current collecting gate lines is equal.

[0022] In a possible implementation of the first aspect, the pitch between the bus gate line and the adjacent interconnection gate line is 5.2mm-5.6mm;

[0023] And / or, in the same column of the current collecting gate lines, the pitch between the two adjacent current collecting gate lines is 0.6mm-1.4mm;

[0024] And / or, in the first direction, the pitch between each of the first side gate lines and the adjacent second side gate lines in the two adjacent columns of the current collecting gate lines is 0.3mm-0.7mm.

[0025] In a possible implementation of the first aspect, in the same pair of the current collecting gate lines, the two connection sections are overlapping parts of the two current collecting gate lines in the second direction, and the length of a single connection section is 0.5%-10% of the length of a single current collecting gate line.

[0026] In a possible implementation of the first aspect, the current collecting gate line is linear;

[0027] And / or, the length of the current collecting gate line is 5mm-15mm;

[0028] And / or, the width of the current collecting gate line is 10μm-35μm;

[0029] And / or, the length of the connection section is 0.03mm-0.5mm.

[0030] In a possible implementation of the first aspect, at least one side of the bus gate line in the second direction is provided with an overlapping gate line, the connection section overlaps the overlapping gate line, and the maximum dimension of the overlapping gate line in the first direction is greater than the width of the current collecting gate line.

[0031] In a possible implementation of the first aspect, the overlapping gate line comprises a first overlapping section, one end of the first overlapping section is connected with the bus gate line in the second direction and the other end extends to a second overlapping section, and the dimension of the second overlapping section in the first direction narrows along the direction away from the first overlapping section;

[0032] The dimension of the overlapping gate line in the second direction is 5μm-4000μm;

[0033] The dimension of the second overlapping section in the second direction is ≤3000μm;

[0034] The size of the first overlap section in the second direction is 5 μm-1000 μm;

[0035] The maximum size of the overlap grid line in the first direction is the size of the first overlap section in the first direction, and the size of the first overlap section in the first direction is 20 μm-80 μm.

[0036] The minimum size of the second overlap section in the first direction is 10 μm-35 μm.

[0037] In a possible implementation manner of the first aspect, the bus grid line has two branch sections at least at one end, the two branch sections are arranged at intervals in the second direction, and two bus grid lines of at least one pair of the bus grid lines are respectively overlapped with the two branch sections.

[0038] And / or, the bus grid line is further provided with a welding part.

[0039] In a possible implementation manner of the first aspect, the solar cell further comprises a doped layer, a front functional film, an interface passivation layer, a doped polysilicon layer, a back functional film, and a back grid line, the substrate is a silicon substrate, the doped layer and the front functional film are arranged on the front surface of the silicon substrate in a direction away from the silicon substrate, the bus grid line is arranged on the side of the front functional film away from the silicon substrate, the bus grid line is overlapped with the doped layer, and the bus grid line is in ohmic contact with the doped layer through the front functional film, the interface passivation layer, the doped polysilicon layer, and the back functional film are arranged on the back surface of the silicon substrate in a direction away from the silicon substrate, and the back grid line is in ohmic contact with the doped polysilicon layer through the back functional film.

[0040] And / or, the first direction is perpendicular to the second direction.

[0041] In a second aspect, the embodiments of the present application disclose a printing screen assembly for preparing the solar cell of the first aspect, and the printing screen assembly comprises:

[0042] A first printing screen, wherein the first printing screen is provided with bus grid line printing holes configured to print the bus grid line; and

[0043] The second printing screen has a plurality of full-open current collecting grid line printing holes, which are configured to print the current collecting grid lines; the extension direction of the current collecting grid line printing holes on the surface of the second printing screen is a third direction; two current collecting grid line printing holes are arranged to form a pair in the third direction; in each pair of current collecting grid line printing holes, the two current collecting grid line printing holes are staggered in the third direction and a fourth direction, the fourth direction being a direction intersecting the third direction on the surface of the second printing screen; in the third direction, each of the two current collecting grid line printing holes has a connecting section printing part at the end close to the other, and the two connecting section printing parts are respectively overlapping parts of the two current collecting grid line printing holes in the third direction.

[0044] In a possible implementation of the second aspect, the first printing screen further has interconnecting grid line printing holes configured to print interconnecting grid lines, the interconnecting grid line printing holes and the bus bar grid line printing holes extend in the same direction on the surface of the first printing screen and have a fifth direction as the extension direction, and the interconnecting grid line printing holes and the bus bar grid line printing holes are spaced apart in a sixth direction intersecting the fifth direction.

[0045] In a possible implementation of the second aspect, in the sixth direction, at least one side of the bus bar grid line printing hole is provided with an overlapping grid line printing hole extending in the sixth direction;

[0046] The overlapping grid line printing hole includes a first overlapping section printing part, in the sixth direction, one end of the first overlapping section printing part is connected to the bus bar grid line printing hole, and the other end extends to a second overlapping section printing part, and the size of the second overlapping section printing part in the fifth direction narrows in a direction away from the first overlapping section printing part.

[0047] In a possible implementation of the second aspect, the size of the overlapping grid line printing hole in the sixth direction is 5 μm to 4000 μm;

[0048] The size of the second overlapping section printing part in the sixth direction is ≤3000 μm;

[0049] The size of the first overlapping section printing part in the sixth direction is 5 μm to 1000 μm;

[0050] The size of the first overlapping section printing part in the fifth direction is 15 μm to 60 μm;

[0051] The minimum size of the second overlapping section printing part in the fifth direction is 10 μm to 30 μm.

[0052] In a possible implementation of the second aspect, a width of the bus bar printing hole is greater than a width of the interconnection grid line printing hole.

[0053] In a possible implementation of the second aspect, the width of the bus bar printing hole is 15 μm to 40 μm.

[0054] And / or, the width of the interconnection grid line printing hole is 10 μm to 30 μm.

[0055] In a possible implementation of the second aspect, the bus bar printing hole is bifurcated at at least one end to have two branch segment printing portions, the two branch segment printing portions are arranged at intervals in the sixth direction, and each of the branch segment printing portions is configured to print a branch segment of the bus bar.

[0056] And / or, the bus bar printing hole is further provided with a to-be-welded portion printing hole, the to-be-welded portion printing hole is configured to print a to-be-welded portion on the bus bar.

[0057] And / or, the fifth direction and the sixth direction are perpendicular to each other.

[0058] In a possible implementation of the second aspect, a plurality of the current collecting grid line printing holes are arranged at intervals along the fourth direction to form a column, and a plurality of columns of the current collecting grid line printing holes are arranged along the third direction.

[0059] Among the two adjacent columns of the current collecting grid line printing holes, one column of the current collecting grid line printing holes is a first side grid line printing hole, and the other column of the current collecting grid line printing holes is a second side grid line printing hole, the first side grid line printing hole and the second side grid line printing hole are arranged alternately in the fourth direction, and any first side grid line printing hole and an adjacent second side grid line printing hole form a pair of the current collecting grid line printing holes.

[0060] In a possible implementation of the second aspect, in the same column of the current collecting grid line printing holes, the plurality of the current collecting grid line printing holes are arranged at equal intervals.

[0061] And / or, in the fourth direction, the interval between each first side grid line printing hole and an adjacent second side grid line printing hole in the two adjacent columns of the current collecting grid line printing holes is equal.

[0062] In a possible implementation of the second aspect, in the same column of the current collecting grid line printing holes, the interval between two adjacent current collecting grid line printing holes is 0.6 mm to 1.4 mm.

[0063] And / or, in the fourth direction, the interval between each first side grid line printing hole and an adjacent second side grid line printing hole in the two adjacent columns of the current collecting grid line printing holes is 0.3 mm to 0.7 mm.

[0064] In a possible implementation of the second aspect, a length of the single connection segment printing part is 0.5% to 10% of a length of the single current collecting grid line printing hole.

[0065] In a possible implementation of the second aspect, a width of the current collecting grid line printing hole is 5 to 15 μm.

[0066] In a possible implementation of the second aspect, a length of the current collecting grid line printing hole is 5 to 15 mm.

[0067] In a possible implementation of the second aspect, a length of the connection segment printing part is 0.03 to 0.5 mm.

[0068] In a possible implementation of the second aspect, the second printing screen is a metal film printing screen.

[0069] In a possible implementation of the second aspect, the third direction is perpendicular to the fourth direction.

[0070] In a third aspect, the embodiments of the present application disclose a photovoltaic module, comprising a plurality of series and / or parallel solar cells, at least one of the solar cells being the solar cell of the first aspect, or at least one of the solar cells being made by using the printing screen assembly of the second aspect.

[0071] Compared with the prior art, the beneficial effects of the present application include: in each pair of current collecting grid lines of the solar cell, the two current collecting grid lines are staggered in the first direction and the second direction, that is, the two current collecting grid lines are discontinuous and staggered. In the related art, current transmission is performed by a continuous grid line extending on the substrate surface, and the size of the continuous grid line is comparable to that of the substrate. The solar cell provided by the present application can cover a larger range of substrate surface through a pair of discontinuous current collecting grid lines, and the single current collecting grid line is smaller than the size of the substrate in the second direction, the current collecting grid line printing hole used for printing the current collecting grid line is also shorter, thereby making the printing screen have better structural strength and reducing the phenomenon of printing deviation and grid line being too thick.

[0072] In each pair of current collecting grid lines, the two current collecting grid lines each have a connection segment at an end close to each other. At least one pair of current collecting grid lines is lapped on the bus grid line through the two connection segments, and at least one connection segment passes through the bus grid line in the second direction. When the bus grid line is welded with the solder strip, the solder strip can still be connected with the two current collecting grid lines and the bus grid line through the connection segment when the solder strip is deviated relative to the bus grid line. In other words, the two connection segments provide a margin for the solder strip alignment deviation.

[0073] In summary, the solar cell improves the grid line layout mode, effectively shortens the opening length on the printing screen to make the printing screen have better structural strength, and reduces the phenomenon of printing deviation and grid line being too thick, and the connection segment is provided to provide a margin for the solder strip alignment deviation. BRIEF DESCRIPTION OF DRAWINGS

[0074] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0075] Figure 1 This is a schematic diagram of the electrode structure of a solar cell disclosed in the first aspect of this application;

[0076] Figure 2 for Figure 1 A magnified view of a portion of region I shown in the diagram;

[0077] Figure 3 for Figure 1 A magnified view of a portion of region II shown in the diagram;

[0078] Figure 4 for Figure 1 Another enlarged view of region II shown in the diagram;

[0079] Figure 5 for Figure 1 Another enlarged view of region II shown in the diagram;

[0080] Figure 6 This is a schematic diagram of the structure of a pair of collector grids disclosed in the first aspect of this application;

[0081] Figure 7 This is a schematic diagram showing the connection of the busbar and collector grid disclosed in the first aspect of this application;

[0082] Figure 8 for Figure 7 A magnified view of a portion of region III shown in the diagram;

[0083] Figure 9 for Figure 7 Another enlarged view of region III shown in the diagram;

[0084] Figure 10 This is a schematic diagram of another electrode structure of a solar cell disclosed in the first aspect of this application;

[0085] Figure 11 for Figure 10 The AA cross-section shown in the figure;

[0086] Figure 12 for Figure 10 The BB cross-section shown in the figure;

[0087] Figure 13 for Figure 10 The CC cross-section shown in the figure;

[0088] Figure 14 A schematic diagram of the structure of a printing screen assembly disclosed in the second aspect of this application;

[0089] Figure 15 for Figure 14 A magnified view of region IV shown in the diagram;

[0090] Figure 16 for Figure 14 Another enlarged view of region IV shown;

[0091] Figure 17 This is a schematic diagram of the structure of a pair of printed holes for collector grid lines disclosed in the second aspect of this application;

[0092] Figure 18 This is a schematic diagram of the structure of the busbar printed holes disclosed in the second aspect of this application;

[0093] Figure 19 for Figure 18 A magnified view of region V shown in the diagram.

[0094] Explanation of reference numerals in the attached figures:

[0095] 10. Solar cell; 11. Substrate; 111. Doped layer; 112. Front functional film; 113. Interface passivation layer; 114. Doped polycrystalline silicon layer; 115. Back functional film; 12. Busbar; 121. Branch segment; 122. Part to be soldered; 13. Interconnect grid; 14. Collector grid; 14a. First side grid; 14b. Second side grid; 141. Connecting segment; 15. Overlap grid; 151. First overlap segment; 152. Second overlap segment; 16. Back grid; Y1. First direction; X1. Second direction;

[0096] 20. First printing screen; 21. Busbar printing hole; 211. Branch section printing section; 212. Printing hole for section to be welded; 22. Interconnecting grid printing hole; 23. Overlapping grid printing hole; 231. First overlapping section printing section; 232. Second overlapping section printing section; Y3, Fifth direction; X3, Sixth direction;

[0097] 30. Second printing screen; 31. Collector grid line printing hole; 31a. First side grid line printing hole; 31b. Second side grid line printing hole; 311. Connecting section printing part; X2. Third direction; Y2. Fourth direction. Detailed Implementation

[0098] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0099] In the present application, the terms "set", "provided with", "connected", and "linked" should be interpreted broadly. For example, it can be fixedly connected, detachably connected, or integrally configured; it can be mechanically connected or electrically connected; it can be directly connected, indirectly connected through an intermediate medium, or internally connected between two devices, elements or components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present application according to the specific circumstances.

[0100] In addition, the terms "first", "second", and the like are mainly used to distinguish different devices, elements or components (the specific types and configurations can be the same or different), and are not intended to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, the meaning of "multiple" is two or more.

[0101] The collecting grid lines of the solar cell can be printed by using a steel screen plate. The steel screen plate is made of a steel screen cloth, and the steel screen cloth is woven by steel wires. Since there are steel wires in the printing holes on the steel screen plate, the opening rate is generally about 80%, and the unopened position, i.e. the position where the steel wire exists, will affect the permeability of the paste. When the steel screen plate is used to print the relatively narrow collecting grid lines, the poor permeability of the paste will cause the collecting grid lines to be more prone to printing abnormalities. In other words, the steel screen plate is not suitable for printing the collecting grid lines with relatively narrow line width, and thus is not conducive to the solar cell to reduce the paste material by narrowing the line width of the collecting grid lines.

[0102] Fully open printing screens are more suitable for printing narrower linewidth current collector lines, such as metal film printing screens. This is because the printing holes on such screens are fully open, with no steel wires obstructing the flow. The ink passes through the holes unobstructed, resulting in good ink permeability. However, since the printing holes are fully open and lack internal steel wires for stretching, the inner walls of the holes are essentially disconnected. Understandably, if the length of the printing holes is too large, the structural strength of the printing screen will be significantly affected. Furthermore, to better transmit current, the current collector line pattern of a solar cell is a continuous straight line, with a length comparable to the substrate size. Correspondingly, the printing holes for printing this straight current collector line are also straight openings with a length comparable to the size of the printing screen. Excessively long printing holes will lead to a decrease in the structural strength of the printing screen. On the other hand, since there is no steel wire to stretch each other in the fully open printing holes, when the squeegee applies force to the printing screen, the fully open printing holes are prone to deformation, change position and enlargement, resulting in printing offset and coarse grids. Moreover, the above situation will increase and become more serious as the length of the printing holes increases.

[0103] The inventors discovered that the collector grid lines of solar cells can be designed as intermittent collector grid lines to shorten the length of the collector grid lines, thereby shortening the length of the printed vias. However, if the ends of the intermittent collector grid lines only just overlap the busbars, a slight misalignment during soldering can lead to poor contact between the solder strips and both the busbars and collector grid lines.

[0104] Based on the above analysis, this application provides a solar cell that effectively shortens the opening length on the printing screen by improving the grid layout, thereby giving the printing screen better structural strength and reducing printing offset and excessively thick grid lines. Furthermore, by setting connecting sections that pass through the busbar grid lines, it provides leeway for solder ribbon alignment offset.

[0105] The technical solution of this utility model will be described below with reference to the embodiments and accompanying drawings.

[0106] Firstly, see [the following] Figure 1 and Figure 2 This application discloses a solar cell 10, including a substrate 11, a plurality of busbars 12 and a plurality of collector grids 14.

[0107] Each bus gate line 12 is disposed on the surface of the substrate 11, and the extension direction of the bus gate line 12 on the surface of the substrate 11 is the first direction Y1.

[0108] Each collector gate line 14 is disposed on the surface of the substrate 11 and extends along a second direction X1, which intersects with the first direction Y1. Two collector gate lines 14 are arranged in a pair along the second direction X1. In each pair of collector gate lines 14, the two collector gate lines 14 are staggered in both the first direction Y1 and the second direction X1. In the second direction X1, the ends of the two collector gate lines 14 closest to each other each have a connecting section 141.

[0109] In this configuration, at least one pair of collector grid lines 14 have two connecting segments 141 that overlap on the bus grid line 12, and at least one connecting segment 141 passes through the bus grid line 12 in the second direction X1.

[0110] In this solar cell 10, the two pairs of collector grid lines 14 are staggered in both the first direction Y1 and the second direction X1, meaning the two collector grid lines 14 are discontinuous and staggered. In related technologies, current is transferred by extending a continuous grid line on the substrate surface, and this continuous grid line is approximately the same size as the substrate. The solar cell 10 of this application can cover a large area of ​​the substrate 11 surface through a pair of discontinuous collector grid lines 14, and each individual collector grid line 14 is smaller than the size of the substrate 11 in the second direction X1. The printing holes for printing the collector grid lines 14 are also shorter, resulting in a printing screen with better structural strength and reduced printing misalignment and excessively thick grid lines.

[0111] In each pair of collector grid lines 14, each of the two collector grid lines 14 has a connecting segment 141 at one end closest to the other. At least one pair of collector grid lines 14 is overlapped on the busbar 12 by two connecting segments 141, and at least one connecting segment 141 passes through the busbar 12 in the second direction X1. This can be understood as: in the same pair of collector grid lines 14, only one connecting segment 141 passes through the busbar 12 in the second direction X1, or both connecting segments 141 pass through the busbar 12 in the second direction X1. The term "passes through" means that the connecting segment 141 passes through the busbar 12 from one side and extends from the other side, forming a "+" or "X" shaped structure. The term "overlapped" means that the two connecting segments 141 are connected to the busbar 12 in a stacked manner.

[0112] Thus, when the busbar 12 is welded to the solder strip, even if the solder strip is offset relative to the busbar 12 in the second direction X1, it can still be connected to the two collector lines 14 and the busbar 12 through the connecting section 141. In other words, the two connecting sections 141 provide leeway for the solder strip alignment offset.

[0113] In summary, the solar cell 10 effectively shortens the opening length on the printing screen plate by improving the layout of the grid lines, so that the printing screen plate has better structural strength, and the phenomenon of printing deviation and grid line over-thickness is reduced. By providing the connecting section 141 passing through the bus grid line 12, a margin is provided for the alignment deviation of the solder strip.

[0114] It should be noted that the number of bus grid lines 12 can be one or more, for example two, three or four; the number of current collecting grid lines 14 is not less than two, for example the number of current collecting grid lines 14 can be tens to hundreds; accordingly, the current collecting grid lines 14 overlapped on the bus grid line 12 can be multiple pairs, for example tens of pairs, which is not limited in the embodiments of the present application.

[0115] Optionally, the first direction Y1 is perpendicular to the second direction X1, that is, the current collecting grid line 14 is perpendicular to the bus grid line 12 and the interconnection grid line 13. It should be noted that the first direction Y1 and the second direction X1 are both directions on the surface of the substrate 11. Of course, the angle between the first direction Y1 and the second direction X1 can also be other angles, for example 80°, 85° or 89°.

[0116] It can be understood that the current collecting grid line 14 is equivalent to being disconnected at the position where the bus grid line 12 is provided. It can be understood that the more the disconnection positions, the shorter the length of the current collecting grid line 14, the better the strength of the printing screen plate, and the less the phenomenon of printing deviation and grid line over-thickness. However, if the number of bus grid lines 12 is increased to increase the disconnection position of the current collecting grid line 14, the setting density of the bus grid line 12 will reach a certain degree, which will be difficult to weld, and the too dense bus grid line 12 will also cause a large shading loss of the solar cell 10.

[0117] Based on this, in some embodiments, referring to Figure 2 The solar cell 10 further comprises an interconnection grid line 13, the interconnection grid line 13 extends along the first direction Y1, and the interconnection grid line 13 is arranged at intervals with the bus grid line 12 in the second direction X1.

[0118] In the second direction X1, among the three current collecting grid lines 14, the first current collecting grid line 14 and the second current collecting grid line 14 form a pair of current collecting grid lines 14, and the second current collecting grid line 14 and the third current collecting grid line 14 form another pair of current collecting grid lines 14, wherein the two connecting sections 141 of the pair of current collecting grid lines 14 are overlapped on the bus grid line 12, and the two connecting sections 141 of the other pair of current collecting grid lines 14 are overlapped on the interconnection grid line 13.

[0119] The bus grid line 12 is configured to collect the current in the above-mentioned current collecting grid line 14, and the interconnection grid line 13 is configured to conduct the current on the current collecting grid line 14 to another current collecting grid line 14.

[0120] In this embodiment, the current collecting grid lines 14 can not only be overlapped with the bus grid lines 12 at the disconnection positions, but also be overlapped with the interconnecting grid lines 13 at the disconnection positions. Some of the current collecting grid lines 14 are overlapped between the bus grid lines 12 and the interconnecting grid lines 13, so that the current of the current collecting grid lines 14 overlapped with the interconnecting grid lines 13 can be collected to the bus grid lines 12. In this way, the bus grid lines 12 of the solar cell 10 can maintain a proper distribution density for welding. Meanwhile, the disconnection positions of the current collecting grid lines 14 are further shortened by the interconnecting grid lines 13, which is beneficial to maintaining a good structural strength of the printing screen for printing the current collecting grid lines 14, and lessens the printing deviation and the thick grid lines.

[0121] Preferably, the width of the bus grid lines 12 is greater than the width of the interconnecting grid lines 13. The interconnecting grid lines 13 are used to conduct the current between the current collecting grid lines 14, and do not need to be welded with the solder strips, i.e. the interconnecting grid lines 13 have a lower requirement for the width. The interconnecting grid lines 13 can be relatively narrower than the bus grid lines 12, and the shading area of the interconnecting grid lines 13 is relatively smaller than that of the bus grid lines 12. In other words, the solar cell 10 increases the disconnection positions of the current collecting grid lines 14 by setting the interconnecting grid lines 13, and the shading area and the paste consumption of the interconnecting grid lines 13 are both less, which is beneficial to reducing the cost and increasing the efficiency of the solar cell 10.

[0122] If the width of the bus grid lines 12 is less than 25 μm, the performance of the bus grid lines 12 is poor, such as the conductivity and the welding performance. If the width of the bus grid lines 12 is greater than 100 μm, the shading area of the bus grid lines 12 is large and the paste consumption for printing is excessive. Preferably, the width of the bus grid lines 12 is 25 μm to 100 μm, including any point value in the width range, such as 25 μm, 50 μm or 100 μm. The bus grid lines 12 in the width range can have both good conductivity and welding performance, and have a small shading area, so that the paste consumption for printing is less.

[0123] If the width of the interconnecting grid lines 13 is less than 20 μm, the conductivity of the interconnecting grid lines 13 is poor and the electric loss is large. If the width of the interconnecting grid lines 13 is greater than 50 μm, the shading area of the interconnecting grid lines 13 is large and the paste consumption for printing is excessive. Preferably, the width of the interconnecting grid lines 13 is 20 μm to 50 μm, including any point value in the width range, such as 20 μm, 35 μm or 50 μm. The interconnecting grid lines 13 in the width range have both low electric loss and small shading area, so that the paste consumption for printing is less.

[0124] The current collecting grid lines will be described in detail below.

[0125] In some embodiments, referring to Figure 3The plurality of current collecting grid lines 14 are arranged in a column along the first direction Y1, and a plurality of columns of current collecting grid lines 14 are arranged along the second direction X1, and two adjacent columns of current collecting grid lines 14 are overlapped on the same bus grid line 12 or the same interconnecting grid line 13.

[0126] In this way, the current collecting grid lines 14 are distributed on the surface of the substrate 11 along the first direction Y1 and the second direction X1, and the current is collected more efficiently.

[0127] Optionally, in the same column of current collecting grid lines 14, the plurality of current collecting grid lines 14 are equidistantly arranged, so as to better collect the current in the region. Correspondingly, the current collecting grid line printing holes on the printing screen plate are also equidistantly arranged, which is beneficial to the force balance of the printing screen plate, so as to maintain a good structural strength of the printing screen plate and improve the service life of the printing screen plate.

[0128] Further, in the same column of current collecting grid lines 14, if the distance between two adjacent current collecting grid lines 14 is less than 0.6 mm, the current collecting grid lines 14 are distributed too densely, which will result in an increase in the overall light shielding area, and the distribution of the current collecting grid line printing holes on the printing screen plate is also too dense, which will result in a decrease in the strength of the printing screen plate. If the distance between two adjacent current collecting grid lines 14 is greater than 1.4 mm, the current collecting grid lines 14 are distributed too sparsely, which will result in a decrease in the current collecting effect. Preferably, in the same column of current collecting grid lines 14, the distance D1 between two adjacent current collecting grid lines 14 is 0.6 mm to 1.4 mm, including any point value within the range, for example, 0.6 mm, 1.0 mm or 1.4 mm. Within the range, the current collecting effect of the current collecting grid lines 14 is better, and the total light shielding area of a column of current collecting grid lines 14 is smaller. Correspondingly, the strength of the printing screen plate is also better.

[0129] Referring to Figure 4 In the two adjacent columns of current collecting grid lines, one of the columns of current collecting grid lines is a first side grid line 14a, and the other column of current collecting grid lines is a second side grid line 14b. In the first direction Y1, the first side grid lines 14a and the second side grid lines 14b are arranged alternately, and any first side grid line 14a and an adjacent second side grid line 14b form a pair of current collecting grid lines. That is, the two adjacent columns of current collecting grid lines form a plurality of pairs of current collecting grid lines.

[0130] Optionally, in the two adjacent columns of current collecting grid lines, in the first direction Y1, the distance between each first side grid line 14a and the adjacent second side grid line 14b is equal. In the two adjacent columns of current collecting grid lines, the first side grid lines 14a and the second side grid lines 14b are distributed more uniformly, which is beneficial to improve the current collecting effect. Moreover, the first side grid line printing holes and the second side grid line printing holes on the printing screen plate are also distributed more uniformly, so that the printing screen plate maintains a good structural strength.

[0131] Further, in the first direction Y1, the distance D2 between each first side gate line 14a and the adjacent second side gate line 14b in the two adjacent rows of the current collecting gate lines 14 is 0.3mm-0.7mm, including any point value within the range, for example, 0.3mm, 0.5mm or 0.7mm, and the current collecting gate lines 14 are distributed more uniformly, which can further improve the current collecting effect of the current collecting gate lines 14.

[0132] Referring to Figure 5 Further, in the second direction X1, the bus gate lines 12 and the interconnecting gate lines 13 are arranged alternately, and the Nth row of the current collecting gate lines 14 and the N+1th row of the current collecting gate lines 14 are overlapped on the same interconnecting gate line 13; wherein N is a positive integer; for example, N is 1, 2, 3 or 4, etc., which is not limited in the embodiments of the present application.

[0133] The N+1th row of the current collecting gate lines 14 and the N+2th row of the current collecting gate lines 14 are overlapped on the same bus gate line 12. And / or, the Nth row of the current collecting gate lines 14 and the N-1th row of the current collecting gate lines 14 are overlapped on the same bus gate line 12.

[0134] In general, due to the alternately arranged bus gate lines 12 and the interconnecting gate lines 13, in the two adjacent rows of the current collecting gate lines 14, at least one row of the current collecting gate lines 14 is overlapped with one bus gate line 12, which is conducive to the bus gate line 12 to collect the current of the above-mentioned current collecting gate lines 14, improves the current transmission effect, and can shorten the power transmission path of the current collecting gate lines 14 and reduce the power loss.

[0135] Optionally, the distance between each bus gate line 12 and the adjacent interconnecting gate line 13 is equal. Since the distance between the bus gate line 12 and the interconnecting gate line 13 limits the length of each current collecting gate line 14 in the one row of the current collecting gate lines 14 between them. Since the distance between each bus gate line 12 and the adjacent interconnecting gate line 13 is equal, the length of the current collecting gate line 14 in the different rows of the current collecting gate lines 14 is relatively consistent, that is, the length of the current collecting gate line 14 at each location is relatively short, and the power transmission path is relatively short, and the power loss is relatively low. Accordingly, the length of the current collecting gate line printing hole on the printing screen is relatively consistent, that is, the length of the current collecting gate line printing hole at each location is relatively short, the overall structural strength of the printing screen is relatively good, and the service life of the printing screen is relatively long.

[0136] Further, if the interval between each busbar grid line 12 and the adjacent interconnection grid line 13 is less than 5.2 mm, it indicates that the busbar grid line 12 and the interconnection grid line 13 are distributed too densely, the total shading area of the grid lines is larger, and the paste consumption is more, which is not conducive to the cost reduction and efficiency improvement of the solar cell 10. If the interval between each busbar grid line 12 and the adjacent interconnection grid line 13 is greater than 5.6 mm, the current collecting grid line 14 needs a longer length to be overlapped between the busbar grid line 12 and the adjacent interconnection grid line 13, correspondingly, the structural strength of the printing screen plate will decrease, and the printing abnormality problems will increase. Preferably, the interval D3 between the busbar grid line 12 and the adjacent interconnection grid line 13 is 5.2 mm to 5.6 mm, including any point value within the interval range, for example, 5.2 mm, 5.4 mm or 5.6 mm, the total shading area of the grid lines is smaller, the paste consumption is less, and the structural strength of the printing screen plate is better, and the printing abnormality problems of the current collecting grid line 14 are less.

[0137] In some embodiments, referring to Figure 6 , the current collecting grid line 14 is in a straight line shape. Correspondingly, the current collecting grid line printing hole is also in a straight line shape, which is more conducive to maintaining the better structural strength of the printing screen plate and can be easily realized during processing.

[0138] It can be understood that in the same pair of current collecting grid lines 14, the two connection sections 141 are the overlapping parts of the two current collecting grid lines 14 in the second direction X1, that is, the two current collecting grid lines 14 are only partially staggered in the second direction X1. If the length proportion of the connection section 141 is less than 0.5%, it is difficult to meet the offset range during the welding of the solder strip. If the length proportion of the connection section 141 is greater than 10%, in the same pair of current collecting grid lines 14, the overlapping part of the lengths of the two current collecting grid lines 14 is too much, which will affect the extension length of the two current collecting grid lines 14, the area covered by the two current collecting grid lines 14 in the second direction X1 is smaller, which is not conducive to the collection of current. Correspondingly, the overlapping part of the current collecting grid line printing holes on the printing screen plate is also more, which will not be conducive to the structural strength of the printing screen plate. Preferably, the length L1 of the single connection section 141 is 0.5% to 10% of the length L2 of the single current collecting grid line 14, including any point value within the proportion range, for example, 0.6%, 1%, 3%, 5%, 8% or 10%, which not only meets the offset range during the positioning of the solder strip, but also better collects the current, and the overall structural strength of the printing screen plate is better.

[0139] It can be understood that if the length of the collector grid line 14 is less than 5 mm, the collector grid line 14 has more disconnection positions, and correspondingly, more bus grid lines 12 or interconnecting grid lines 13 are needed for lapping. The thicker bus grid line 12 or interconnecting grid line 13 will result in an increase in the light-shielding area. If the length of the collector grid line 14 is greater than 30 mm, the collector grid line printing hole is also longer, the structural strength of the printing screen is reduced, and the phenomenon of printing deviation and grid line thickening is increased. Preferably, the length L2 of the collector grid line 14 is 5 mm to 30 mm, including any point value in the length range, for example, 5 mm, 10 mm, 20 mm or 30 mm. In this way, the distribution density of the bus grid line 12 and the interconnecting grid line 13 is reasonable, the light-shielding loss of the solar cell 10 is reduced, the printing screen can maintain a good structural strength, and the phenomenon of printing deviation and grid line thickening is reduced.

[0140] It can be understood that if the length of the connecting section 141 is less than 0.03 mm, it is difficult to meet the offset range of the solder strip. If the length of the connecting section 141 is greater than 0.5 mm, the length of the overlap of the two collector grid lines 14 is too long, the length of the overlap of the two collector grid line printing holes is too long, and the strength of the printing screen is reduced. The length L1 of the connecting section 141 is 0.03 mm to 0.5 mm, including any point value in the length range, for example, 0.03 mm, 0.3 mm or 0.5 mm. The connecting section 141 in the length range can meet the offset range of the solder strip and maintain the printing screen at a good structural strength.

[0141] It can be understood that if the width of the collector grid line 14 is less than 10 μm, the electrical performance of the collector grid line 14 will be reduced, and the phenomenon of grid disconnection is prone to occur, and the printing difficulty is increased. If the width of the collector grid line 14 is greater than 35 μm, the light-shielding area of the collector grid line 14 is increased, and the consumption of the paste is increased. Preferably, the width of the collector grid line 14 is 10 μm to 35 μm, including any point value in the width range, for example, 10 μm, 20 μm or 35 μm. The collector grid line 14 in the width range has good electrical performance and a small light-shielding area, and can reduce the required paste for printing and reduce the printing difficulty.

[0142] The bus grid line will be described in detail below.

[0143] Since the bus grid line needs to be welded with the solder strip during the series connection of the solar cell, the narrower collector grid line is prone to disconnection at the lapping position of the bus grid line due to high temperature welding.

[0144] Based on this, referring to Figure 7 and Figure 8In some embodiments, at least one side of the busbar 12 in the second direction X1 is provided with the overlap grid line 15, and the connecting segment 141 overlaps the overlap grid line 15, and the maximum dimension of the overlap grid line 15 in the first direction Y1 is greater than the width of the current collecting grid line 14. It should be noted that the width of the current collecting grid line 14 refers to the dimension of the current collecting grid line 14 in the first direction Y1.

[0145] It can be understood that the wider overlap grid line 15 can improve the overlap effect of the current collecting grid line 14 and the busbar 12, and reduce the phenomenon of broken grid after welding. Moreover, when the current collecting grid line 14 is printed offset, the current collecting grid line 14 can still be connected to the busbar 12 by means of the wider overlap grid line 15.

[0146] It should be noted that the at least one side of the busbar 12 provided with the overlap grid line 15 can be explained as that one side of the busbar 12 is provided with the overlap grid line 15, or both sides of the busbar 12 are provided with the overlap grid line 15.

[0147] Optionally, the overlap grid line 15 comprises a first overlap segment 151, one end of the first overlap segment 151 is connected to the busbar 12 in the second direction X1, and the other end extends to a second overlap segment 152, and the dimension of the second overlap segment 152 in the first direction Y1 narrows in the direction away from the first overlap segment 151. Since the position close to the busbar 12 has a higher temperature during welding, the position of the current collecting grid line 14 close to the busbar 12 can be overlapped with the busbar 12 by means of the wider first overlap segment 151, which can effectively reduce the phenomenon of broken grid. The overlap grid line 15 also overlaps the current collecting grid line 14 by means of the narrowed second overlap segment 152, which takes into account the lower light shielding area and good overlap effect.

[0148] Referring to Figure 9 If the dimension of the overlap grid line 15 in the second direction X1 is less than 5 μm, it is difficult to effectively improve the overlap effect of the current collecting grid line 14 and the busbar 12, and the current collecting grid line 14 is still prone to broken grid during welding. If the dimension of the overlap grid line 15 in the second direction X1 is greater than 4000 μm, the light shielding area of the overlap grid line 15 will increase, and the printing consumes more paste. Preferably, the dimension D4 of the overlap grid line 15 in the second direction X1 is 5 μm to 4000 μm, including any point value in the range, for example, 5 μm, 100 μm, 500 μm, 2000 μm or 4000 μm. The overlap grid line 15 in the dimension range can effectively improve the overlap effect of the current collecting grid line 14 and the busbar 12, and has a smaller light shielding area, and consumes less paste during printing.

[0149] It can be understood that the size D5 of the second overlap section 152 in the second direction X1 is less than or equal to 3000 μm, including any point value in the size range, for example, 5 μm, 100 μm, 500 μm, 1000 μm or 3000 μm, and the second overlap section 152 in the size range can improve the overlap effect of the current collecting grid line 14 and the bus grid line 12, and has a smaller light shielding area.

[0150] It can be understood that the size D6 of the first overlap section 151 in the second direction X1 is 5 μm to 1000 μm, including any point value in the size range, for example, 5 μm, 100 μm, 500 μm or 1000 μm, and the first overlap section 151 in the size range can effectively reduce the grid break phenomenon of the current collecting grid line 14, and has a smaller light shielding area.

[0151] It can be understood that the maximum size of the overlap grid line 15 in the first direction Y1 is the size D7 of the first overlap section 151 in the first direction Y1. If the size of the first overlap section 151 in the first direction Y1 is less than 20 μm, the printing offset of the current collecting grid line 14 in the first direction Y1 is prone to fail to overlap with the overlap section, and the conductive performance and the anti-grid break performance of the first overlap section 151 will also decrease. If the size of the first overlap section 151 in the first direction Y1 is greater than 80 μm, the overall area of the first overlap section 151 increases, the slurry consumption is more, and the light shielding area is larger. The size D7 of the first overlap section 151 in the first direction Y1 is 20 μm to 80 μm, including any point value in the size range, for example, 20 μm, 60 μm or 80 μm, which can allow the current collecting grid line 14 to print offset within a certain range, has good conductive performance and anti-grid break performance, and has a lower light shielding area and a lower slurry usage.

[0152] It can be understood that if the size of the narrowest part of the second overlap section 152 in the first direction Y1 is less than 10 μm, the overlap effect of the second overlap section 152 and the current collecting grid line 14 is poor, and the electrical loss at the overlap is increased. If the size of the narrowest part of the second overlap section 152 in the first direction Y1 is greater than 35 μm, the overall light shielding area of the second overlap section 152 will be larger. Preferably, the minimum size D8 of the second overlap section 152 in the first direction Y1 is 10 μm to 35 μm, including any point value in the size range, for example, 10 μm, 25 μm or 35 μm, which can form a good overlap with the current collecting grid line 14, and has a lower electrical loss and a smaller light shielding area.

[0153] In some embodiments, referring back to Figure 7 , the bus grid line 12 has at least one end bifurcated to have two branch sections 121, and the two branch sections 121 are arranged at intervals in the second direction X1, and two current collecting grid lines 14 of at least one pair of current collecting grid lines 14 are respectively overlapped with the two branch sections 121.

[0154] The bifurcation of at least one end of the busbar grid line 12 can be interpreted as: in the first direction Y1, one end of the busbar grid line 12 is bifurcated; or in the first direction Y1, both ends of the busbar grid line 12 are bifurcated.

[0155] In the embodiment, the bifurcation structure of the end of the busbar grid line 12 can reduce the risk of hidden cracks and false welding when the photovoltaic module is packaged.

[0156] Further, the busbar grid line 12 is also provided with a to-be-welded part 122. The to-be-welded part 122 is, for example, a solder pad. The to-be-welded part 122 is used for welding and fixing the busbar grid line 12 with a solder strip, so as to improve the welding effect. The number of to-be-welded parts 122 on one busbar grid line 12 can be one or more, which is not limited in the embodiment of the present application.

[0157] The other film layer structures of the solar cell will be described in detail below.

[0158] In some embodiments, referring to Figures 10 to 13 The solar cell 10 further includes a doped layer 111, a front functional film 112, an interface passivation layer 113, a doped polysilicon layer 114, a back functional film 115, and a back grid line 16. The substrate 11 is a silicon substrate 11. The doped layer 111 and the front functional film 112 are arranged on the front side of the silicon substrate 11 in a direction away from the silicon substrate 11. The current collecting grid line 14 is in ohmic contact with the doped layer 111 through the front functional film 112. The busbar grid line 12 is arranged on the side of the front functional film 112 away from the silicon substrate 11. The interface passivation layer 113, the doped polysilicon layer 114, and the back functional film 115 are arranged on the back side of the silicon substrate 11 in a direction away from the silicon substrate 11. The back grid line 16 is in ohmic contact with the doped polysilicon layer 114 through the back functional film 115.

[0159] In the embodiment, the solar cell 10 is a passivated contact solar cell. Of course, the solar cell can also be other types of solar cells, such as a heterojunction solar cell.

[0160] Optionally, the silicon substrate 11 can be an N-type silicon substrate or a P-type silicon substrate.

[0161] Optionally, the doped layer 111 can be a diffusion layer, such as a boron diffusion layer or a phosphorus diffusion layer. The doped layer 111 can also be an N-type doped polysilicon layer or a P-type doped polysilicon layer. The conductivity type of the doped layer 111 should be opposite to that of the doped polysilicon layer 114 on the back side of the silicon substrate 11.

[0162] The front functional film 112 and the back functional film 115 can be passivation films and / or anti-reflection films. Of course, the front functional film 112 and the back functional film 115 can be film layers with other functions.

[0163] More specifically, the material of the interface passivation layer 113 can include a variety of dielectric materials, such as at least one of silicon oxide, magnesium fluoride, amorphous silicon, polysilicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. In particular, the interface passivation layer 113 can be composed of a silicon oxide layer containing silicon oxide. This is because a silicon oxide layer has excellent passivation properties, can minimize the recombination loss of minority carriers on the surface of the silicon substrate 11, and is a thin film with excellent durability to subsequent high-temperature processes. The interface passivation layer 113, as a potential barrier for electrons and holes, can be combined with the doped polysilicon layer 114 to prevent the passage of minority carriers. The interface passivation layer 113 can also have a pinhole passage effect, allowing the free movement of carriers within the solar cell 10, resulting in selective passage of majority carriers through the doped polysilicon layer 114, which helps to reduce the recombination loss of minority carriers. In addition, the interface passivation layer 113 can act as a diffusion barrier to prevent the diffusion of dopants from the doped polysilicon layer 114 into the silicon substrate 11.

[0164] In a second aspect, referring to Figure 14 and Figure 15 The embodiments of the present application disclose a printing screen assembly for preparing the solar cell of the first aspect, the printing screen assembly comprising a first printing screen 20 and a second printing screen 30.

[0165] The first printing screen 20 is provided with busbar printing holes 21 configured to print busbars.

[0166] The second printing screen 30 is provided with a plurality of full-open current collecting grid printing holes 31 configured to print current collecting grids. The extension direction of the current collecting grid printing holes 31 on the surface of the second printing screen 30 is a third direction X2. Two current collecting grid printing holes 31 arranged in each pair of current collecting grid printing holes 31 are arranged in the third direction X2 and the fourth direction Y2, and the fourth direction Y2 is a direction intersecting the third direction X2 on the surface of the second printing screen 30. In the third direction X2, each of the two current collecting grid printing holes 31 has a connecting section printing part 311 at the end close to each other, and the two connecting section printing parts 311 are respectively the overlapping parts of the two current collecting grid printing holes 31 in the third direction X2.

[0167] The printing screen assembly is in the second printing screen 30, and the current collecting grid line printing hole 31 is a full opening. The full opening refers to that the opening rate of the current collecting grid line printing hole 31 is 100%. The full opening of the current collecting grid line printing hole 31 refers to that all materials in the opening area are removed along the thickness direction of the second printing screen 30, but there may be unavoidable residual materials at the edge of the opening area. There is no steel wire blockage in the full opening current collecting grid line printing hole 31, and the paste passability is better. The full opening current collecting grid line printing hole 31 can be used to print narrower current collecting grid lines, so as to reduce the amount of paste and reduce costs, and also to reduce the light shielding area of the current collecting grid lines to increase the efficiency of the solar cell.

[0168] However, the longer the length of the full opening current collecting grid line printing hole 31 is, the greater the influence on the structural strength of the second printing screen 30 is. Therefore, the current collecting grid line printing hole 31 in the embodiment of the present application is discontinuously arranged. Specifically, two current collecting grid line printing holes 31 are arranged in pairs in the third direction X2. In each pair of current collecting grid line printing holes 31, the two current collecting grid line printing holes 31 are staggered in the third direction X2 and the fourth direction Y2, that is, the two current collecting grid line printing holes 31 are discontinuous. It can be understood that the present application prints a pair of discontinuous current collecting grid lines through a pair of discontinuous current collecting grid line printing holes 31, instead of the continuous grid lines in the related art. The length of the current collecting grid line printing hole 31 can be shorter, the structural strength of the second printing screen 30 is better, and the phenomenon of offset and thick grid lines during printing of the current collecting grid line printing hole 31 can be reduced.

[0169] In order to make the discontinuous pair of current collecting grid lines lap on the bus grid line, in the embodiment of the present application, in the third direction X2, one end of the two current collecting grid line printing holes 31 close to each other has a connecting section printing part 311, and the two connecting section printing parts 311 are respectively the overlapping parts of the two current collecting grid line printing holes 31 in the third direction X2. That is, the two current collecting grid line printing holes 31 are only partially staggered in the third direction X2, and the two connecting sections printed by the two connecting section printing parts 311 will be lapped on the same bus grid line.

[0170] Preferably, the third direction X2 is perpendicular to the fourth direction Y2. Of course, the angle between the third direction X2 and the fourth direction Y2 can also be other than 90°, for example, 85°, 88° or 89°.

[0171] The second printing screen will be described in detail below.

[0172] Reference Figure 15 In some embodiments, a plurality of current collecting grid line printing holes 31 are arranged in a column along the fourth direction Y2, and a plurality of columns of current collecting grid line printing holes 31 are arranged along the third direction X2.

[0173] In this way, the collector grid line printing holes 31 are distributed more uniformly, the structural strength of the second printing screen is better at each location, and the force is more balanced when in contact with the doctor blade, which is conducive to improving the service life of the second printing screen.

[0174] Optionally, in the same column of collector grid line printing holes 31, the plurality of collector grid line printing holes 31 are equidistantly arranged, and the equidistant distribution of the collector grid line printing holes 31 is conducive to the force balance of the second printing screen 30, thereby maintaining a better structural strength of the second printing screen 30 and improving the service life of the second printing screen 30.

[0175] Preferably, in the same column of collector grid line printing holes 31, the distance D9 between the two adjacent collector grid line printing holes 31 is 0.6mm-1.4mm, including any point value in the distance range, for example, 0.6mm, 1.0mm or 1.4mm. In this distance range, the structural strength of the second printing screen 30 is better, the current collection effect of the printed collector grid line is better, and the total light shielding area of a column of collector grid lines is smaller.

[0176] Referring to Figure 16 , the two columns of collector grid line printing holes are a first side grid line printing hole 31a and a second side grid line printing hole 31b, the first side grid line printing hole 31a and the second side grid line printing hole 31b are alternately arranged in the fourth direction Y2, and any first side grid line printing hole 31a and the adjacent second side grid line printing hole 31b form a pair of collector grid line printing holes 31.

[0177] The printed collector grid lines are distributed on the surface of the solar cell in multiple directions and have a high distribution density, and can more efficiently collect current.

[0178] Optionally, in the fourth direction Y2, the distance between each first side grid line printing hole 31a and the adjacent second side grid line printing hole 31b in the two columns of collector grid line printing holes is equal.

[0179] In the fourth direction Y2, the distance D10 between each first side grid line printing hole 31a and the adjacent second side grid line printing hole 31b in the two columns of collector grid line printing holes is 0.3mm-0.7mm, including any point value in the distance range, for example, 0.3mm, 0.5mm or 0.7mm. The printed collector grid lines are distributed more uniformly, which can further improve the current collection effect of the collector grid lines.

[0180] In some embodiments, referring to Figure 17If the length proportion of the connection segment printing part 311 in each current collecting grid line printing hole 31 is less than 0.5%, the printed connection segment will be difficult to meet the offset range of the solder strip; if the length proportion of the connection segment printing part 311 is greater than 10%, the overlapping part of the connection segment printing part 311 will be too long to affect the structural strength of the second printing screen plate 30, and also cause the printed current collecting grid line to have insufficient extension length. Preferably, the length L3 of the single connection segment printing part 311 is 0.5% to 10% of the length L4 of the single current collecting grid line printing hole 31, including any point value in the proportion range, for example, 0.6%, 1%, 3%, 5%, 7% or 10%. The second printing screen plate 30 has better structural strength, and the printed current collecting grid line meets the offset range of the solder strip, and also has a larger coverage range on the substrate surface.

[0181] It can be understood that if the length of the current collecting grid line printing hole 31 is less than 5 mm, it means that there are more disconnection positions of the current collecting grid line printing hole 31, and correspondingly, more bus grid lines or interconnecting grid lines are needed for lapping. Thicker bus grid lines or interconnecting grid lines will cause the light shielding area to increase. If the length of the current collecting grid line printing hole 31 is greater than 15 mm, the structural strength of the second printing screen plate 30 will decrease, and the phenomena of printing offset and grid line thickening will increase. Preferably, the length L4 of the current collecting grid line printing hole 31 is 5 mm to 15 mm, including any point value in the length range, for example, 5 mm, 6 mm, 10 mm or 15 mm. In this way, the distribution density of the bus grid lines and the interconnecting grid lines can be reasonably reduced to reduce the shading loss of the solar cell, and the second printing screen plate 30 can be maintained at a good structural strength, and the phenomena of printing offset and grid line thickening can be reduced.

[0182] It can be understood that if the length of the connection segment printing part 311 is less than 0.03 mm, it will be difficult to meet the offset range of the current collecting grid line, and the printed current collecting grid line will still be prone to lapping failure with the bus grid line after printing. If the length of the connection segment printing part 311 is greater than 0.5 mm, the overlapping length of the two current collecting grid line printing holes 31 will be too long, and the strength of the second printing screen plate 30 will decrease. Preferably, the length L3 of the connection segment printing part 311 is 0.03 mm to 0.5 mm, including any point value in the length range, for example, 0.03 mm, 0.3 mm or 0.5 mm. The connection segment printing part 311 in the length range can meet the normal printing offset range of the current collecting grid line, and the structural strength of the second printing screen plate 30 is good.

[0183] It can be understood that if the width of the collector grid line printing hole 31 is less than 5 μm, the printed collector grid line is narrower, the electrical performance is reduced, and the phenomenon of broken grid and the like is prone to occur, and the printing difficulty is increased. If the width of the collector grid line printing hole 31 is greater than 15 μm, the light shielding area of the printed collector grid line is increased, and the wet weight of the slurry is increased. Preferably, the width of the collector grid line printing hole 31 is 5 μm to 15 μm, including any point value in the width range, for example, 5 μm, 10 μm or 15 μm. The collector grid line printing hole 31 in the width range is printed to obtain a collector grid line with good electrical performance and a smaller light shielding area, and can also reduce the wet weight of the slurry and reduce the printing difficulty.

[0184] In the embodiment, the second printing screen is a metal film printing screen, for example, a steel film printing screen. As other examples, the second printing screen can also be a polymer film printing screen or a composite material printing screen, for example, a printing screen made of a composite material composed of a metal film and a polymer film.

[0185] The first printing screen will be described in detail below.

[0186] In some embodiments, with reference back to Figure 14 The first printing screen 20 is also provided with an interconnection grid line printing hole 22 configured to print an interconnection grid line. The interconnection grid line printing hole 22 and the bus grid line printing hole 21 extend in the same direction on the surface of the first printing screen 20 and the extension direction is a fifth direction Y3. The interconnection grid line printing hole 22 and the bus grid line printing hole 21 are arranged at intervals in a sixth direction X3, and the sixth direction X3 intersects the fifth direction Y3.

[0187] Preferably, the fifth direction Y3 and the sixth direction X3 are perpendicular. Of course, the angle between the fifth direction Y3 and the sixth direction X3 can also be other than 90°, for example, 85°, 88° or 89°.

[0188] In order to increase the breaking position of the collector grid line printing hole 31, the first printing screen 20 in the embodiment is also provided with an interconnection grid line printing hole 22 for printing an interconnection grid line. In this way, the collector grid line can not only be broken at the bus grid line, but also be broken at the interconnection grid line. In other words, the breaking position of the collector grid line printing hole 31 is increased and further shortened. Accordingly, the second printing screen 30 maintains good structural strength, and the conditions such as printing offset and thick grid line are less likely to occur.

[0189] In some embodiments, with reference back to Figure 18 and Figure 19 In the sixth direction X3, at least one side of the bus grid line printing hole 21 is provided with an overlapping grid line printing hole 23 extending along the sixth direction X3.

[0190] It should be noted that at least one side of the busbar grid line printing hole 21 is provided with the overlapping grid line printing hole 23, which can be explained as follows: in the sixth direction X3, only one side of the busbar grid line printing hole 21 is provided with the overlapping grid line printing hole 23; or in the sixth direction X3, both sides of the busbar grid line printing hole 21 are provided with the overlapping grid line printing hole 23.

[0191] Further, the overlapping grid line printing hole 23 comprises a first overlapping segment printing part 231, one end of the first overlapping segment printing part 231 is connected with the busbar grid line printing hole 21 in the sixth direction X3 and the other end extends to a second overlapping segment printing part 232, the size of the second overlapping segment printing part 232 in the fifth direction Y3 narrows in the direction away from the first overlapping segment printing part 231.

[0192] The overlapping grid line printing hole 23 can improve the overlapping effect of the current collecting grid line and the busbar grid line by printing a wider overlapping grid line, and reduce the phenomenon of broken grid after welding. When the current collecting grid line is printed offset, the current collecting grid line can still be connected to the busbar grid line by means of the overlapping grid line. To some extent, the overlapping grid line can improve the printing yield of the current collecting grid line.

[0193] It can be understood that if the size of the overlapping grid line printing hole 23 in the sixth direction X3 is less than 5μm, the overlapping grid line printed by the overlapping grid line printing hole 23 is difficult to effectively improve the overlapping effect of the current collecting grid line and the busbar grid line, and the current collecting grid line is still prone to broken grid during welding. If the size of the overlapping grid line printing hole 23 in the sixth direction X3 is greater than 4000μm, the light shielding area of the overlapping grid line printed by the overlapping grid line printing hole 23 will increase, and the wet weight of the paste will be larger. Preferably, the size D11 of the overlapping grid line printing hole 23 in the sixth direction X3 is 5μm-4000μm, including any point value in the size range, for example, 5μm, 100μm, 500μm, 2000μm or 4000μm. The overlapping grid line printed by the overlapping grid line printing hole 23 in the size range can effectively improve the overlapping effect of the current collecting grid line and the busbar grid line, and has a smaller light shielding area and a smaller wet weight of the paste.

[0194] Preferably, the size D12 of the second overlapping segment printing part 232 in the sixth direction X3 is ≤3000μm, including any point value in the size range, for example, 5μm, 100μm, 500μm, 1000μm or 3000μm. The second overlapping segment printed by the second overlapping segment printing part 232 in the size range can improve the overlapping effect of the current collecting grid line and the busbar grid line, and has a smaller light shielding area.

[0195] Preferably, the size D13 of the first overlap segment printing part 231 in the sixth direction X3 is 5 μm to 1000 μm, including any point value in the range, for example 5 μm, 100 μm, 500 μm, 1000 μm. The first overlap segment printed by the first overlap segment printing part 231 in the size range can effectively reduce the phenomenon of broken grid of the current collecting grid line, and has a smaller light shielding area.

[0196] Optionally, the size D14 of the first overlap segment printing part 231 in the fifth direction Y3 is 15 μm to 60 μm, including any point value in the range, for example 15 μm, 30 μm or 60 μm. The current collecting grid line can be printed within a certain range of offset, improve the success rate of overlap, and also reduce the wet weight of the paste, and the overlap segment printed has a smaller light shielding area.

[0197] Optionally, the minimum size D15 of the second overlap segment printing part 232 in the fifth direction Y3 is 10 μm to 30 μm, including any point value in the range, for example 10 μm, 20 μm or 30 μm. The second overlap segment printed has a better overlap effect with the current collecting grid line, and also has a small light shielding area.

[0198] In some embodiments, the width of the busbar grid line printing hole 21 is greater than the width of the interconnection grid line printing hole 22. The interconnection grid line is used to conduct current between the current collecting grid lines, and does not need to be welded with the solder strip, that is, the interconnection grid line has a lower requirement for the width. The interconnection grid line printing hole 22 can be relatively narrower than the busbar grid line printing hole 21, and the light shielding area of the interconnection grid line printed is also smaller relative to the busbar grid line.

[0199] Optionally, the width of the busbar grid line printing hole 21 is 15 μm to 40 μm, including any point value in the range, for example 15 μm, 20 μm or 40 μm. The performance of the busbar grid line printed is better, and the wet weight of the paste and the light shielding area are also smaller.

[0200] Optionally, the width of the interconnection grid line printing hole 22 is 10 μm to 30 μm, including any point value in the range, for example 10 μm, 20 μm or 30 μm. The interconnection grid line printed has good electrical performance, and also has a smaller light shielding area and a smaller wet weight of the paste.

[0201] In some embodiments, with reference to Figure 18 , the busbar grid line printing hole 21 has at least one bifurcated end with two branch segment printing parts 211. The two branch segment printing parts 211 are arranged at intervals in the sixth direction X3, and each branch segment printing part 211 is configured to print a branch segment of the busbar grid line. The bifurcated end structure of the busbar grid line can reduce the risk of hidden cracks and false welding when the photovoltaic module is packaged.

[0202] Optionally, the busbar grid line printing hole 21 is further provided with a to-be-soldered part printing hole 212, and the to-be-soldered part printing hole 212 is configured to print a to-be-soldered part on the busbar grid line. The to-be-soldered part printing hole 212 is used to print a to-be-soldered part, for example, a solder pad, which is used for soldering and fixing the busbar grid line with a solder strip, thereby improving the soldering effect.

[0203] In a third aspect, the embodiments of the present application disclose a photovoltaic module, comprising a plurality of solar cells connected in series and / or in parallel, at least one of the solar cells being the solar cell of the first aspect, or at least one of the solar cells being prepared by using the printing screen assembly of the second aspect.

[0204] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A solar cell, characterized in that, include: Substrate; A plurality of bus gates, each of the bus gates being disposed on the surface of the substrate, and the extension direction of the bus gates on the surface of the substrate being a first direction; as well as Multiple collector gate lines are disposed on the surface of the substrate and extend along a second direction, which intersects the first direction; two collector gate lines are arranged in the second direction to form a pair; in each pair of collector gate lines, the two collector gate lines are staggered in both the first and second directions, and in the second direction, the ends of the two collector gate lines close to each other have a connecting section; In this configuration, at least two of the connecting segments of at least one pair of collector grids overlap the busbar, and at least one of the connecting segments passes through the busbar in the second direction.

2. The solar cell according to claim 1, characterized in that, The solar cell further includes interconnect grid lines extending along the first direction, and the interconnect grid lines and the bus grid lines are spaced apart in the second direction; In the second direction, three collector grid lines are arranged sequentially, with the first collector grid line and the second collector grid line forming a pair of collector grid lines, and the second collector grid line and the third collector grid line forming another pair of collector grid lines. The two connecting segments of one pair of collector grid lines overlap the busbar, and the two connecting segments of the other pair of collector grid lines overlap the interconnect grid line. The bus gate is configured to collect the current within the collector gate, and the interconnect gate is configured to conduct the current on the collector gate to another collector gate.

3. The solar cell according to claim 2, characterized in that, The width of the bus gate is greater than the width of the interconnect gate.

4. The solar cell according to claim 3, characterized in that, The width of the bus gate is 25μm to 100μm, and the width of the interconnect gate is 20μm to 50μm.

5. The solar cell according to claim 2, characterized in that, Multiple collector grid lines are spaced apart in a column along the first direction, and multiple columns of collector grid lines are arranged along the second direction. Two adjacent columns of collector grid lines overlap the same bus grid line or the same interconnect grid line. In two adjacent columns of collector grid lines, one column of collector grid lines is a first side grid line, and the other column of collector grid lines is a second side grid line; in the first direction, the first side grid line and the second side grid line are alternately arranged, and any first side grid line and an adjacent second side grid line form a pair of collector grid lines.

6. The solar cell according to claim 5, characterized in that, In the second direction, the bus gate lines and the interconnect gate lines are alternately arranged, and the Nth column of the collector gate lines and the (N+1)th column of the collector gate lines overlap on the same interconnect gate line; where N is a positive integer; The collector grid line in column N+1 and the collector grid line in column N+2 are connected to the same bus grid line; And / or, the collector grid line in column N and the collector grid line in column N-1 are connected to the same bus grid line.

7. The solar cell according to claim 6, characterized in that, The spacing between each of the bus gates and the adjacent interconnect gates is equal; And / or, in the same column of collector grid lines, multiple collector grid lines are arranged at equal intervals; And / or, in two adjacent columns of collector grid lines, in the first direction, the spacing between each first side grid line and the adjacent second side grid line is equal.

8. The solar cell according to claim 7, characterized in that, The spacing between the busbar and the adjacent interconnecting busbar is 5.2 mm to 5.6 mm; And / or, in the same column of collector grid lines, the spacing between two adjacent collector grid lines is 0.6 mm to 1.4 mm; And / or, in two adjacent columns of collector grid lines, in the first direction, the spacing between each first side grid line and the adjacent second side grid line is 0.3 mm to 0.7 mm.

9. The solar cell according to any one of claims 1 to 8, characterized in that, In the same pair of collector grid lines, the two connecting segments are the overlapping portions of the two collector grid lines in the second direction, and the length of a single connecting segment is 0.5% to 10% of the length of a single collector grid line.

10. The solar cell according to claim 9, characterized in that, The collector grid lines are straight; And / or, the length of the collector grid line is 5mm to 15mm; And / or, the width of the collector grid line is 10μm to 35μm; And / or, the length of the connecting segment is 0.03mm to 0.5mm.

11. The solar cell according to any one of claims 1 to 8, characterized in that, In the second direction, at least one side of the busbar is provided with an overlapping grid line, the connecting section overlaps the overlapping grid line, and the maximum dimension of the overlapping grid line in the first direction is greater than the width of the collector grid line.

12. The solar cell according to claim 11, characterized in that, The overlapping grid line includes a first overlapping section. In the second direction, one end of the first overlapping section is connected to the bus grid line and the other end extends into a second overlapping section. The dimension of the second overlapping section in the first direction narrows in a direction away from the first overlapping section. The dimensions of the overlapping grid lines in the second direction are 5μm to 4000μm; The dimension of the second overlapping segment in the second direction is ≤3000μm; The dimensions of the first overlapping segment in the second direction are 5μm to 1000μm; The maximum dimension of the overlapping grid line in the first direction is the dimension of the first overlapping segment in the first direction, and the dimension of the first overlapping segment in the first direction is 20μm to 80μm; The minimum dimension of the second overlapping segment in the first direction is 10μm to 35μm.

13. The solar cell according to any one of claims 1 to 8, characterized in that, The collector grid line is forked at least one end to have two branch segments, the two branch segments are spaced apart in the second direction, and the two collector grid lines of at least one pair of collector grid lines respectively overlap the two branch segments; And / or, the busbar may also have a section to be welded.

14. The solar cell according to any one of claims 1 to 8, characterized in that, The solar cell further includes a doped layer, a front functional film, an interface passivation layer, a doped polycrystalline silicon layer, a back functional film, and back gate lines. The substrate is a silicon substrate. The doped layer and the front functional film are disposed on the front side of the silicon substrate in a direction away from the silicon substrate. The current collector grid lines pass through the front functional film and make ohmic contact with the doped layer. The bus grid lines are disposed on the side of the front functional film away from the silicon substrate. The interface passivation layer, the doped polycrystalline silicon layer, and the back functional film are disposed on the back side of the silicon substrate in a direction away from the silicon substrate. The back gate lines pass through the back functional film and make ohmic contact with the doped polycrystalline silicon layer. And / or, the first direction is perpendicular to the second direction.

15. A printing screen assembly for preparing a solar cell as described in any one of claims 1 to 14, characterized in that, The printing screen assembly includes: A first printing screen, wherein the first printing screen is provided with busbar printing holes, the busbar printing holes being configured to print the busbars; and A second printing screen has multiple fully open collector wire printing holes configured to print the collector wires. The extension direction of each collector wire printing hole on the surface of the second printing screen is a third direction. Two collector wire printing holes are arranged in this third direction to form a pair. In each pair of collector wire printing holes, the two holes are staggered in the third and fourth directions. The fourth direction is the direction on the surface of the second printing screen that intersects with the third direction. In the third direction, each of the two collector wire printing holes has a connecting section printing portion at one end closest to each other, and the two connecting sections are the overlapping portions of the two collector wire printing holes in the third direction.

16. The printing screen assembly according to claim 15, characterized in that, The first printing screen is further provided with interconnect grid printing holes, which are configured to print interconnect grid lines. The interconnect grid printing holes and the bus grid printing holes extend in the same direction on the surface of the first printing screen and the extension direction is the fifth direction. The interconnect grid printing holes and the bus grid printing holes are spaced apart in the sixth direction, and the sixth direction intersects the fifth direction.

17. The printing screen assembly according to claim 16, characterized in that, In the sixth direction, at least one side of the busbar printing hole is provided with an overlapping grid printing hole, and the overlapping grid printing hole extends along the sixth direction; The overlapping grid line printing hole includes a first overlapping section printing portion. In the sixth direction, one end of the first overlapping section printing portion is connected to the busbar printing hole and the other end extends into a second overlapping section printing portion. The size of the second overlapping section printing portion in the fifth direction narrows in a direction away from the first overlapping section printing portion.

18. The printing screen assembly according to claim 17, characterized in that, The size of the overlapping grid line printing hole in the sixth direction is 5μm to 4000μm; The dimension of the second overlapping section printed portion in the sixth direction is ≤3000μm; The size of the first overlapping section printed portion in the sixth direction is 5μm to 1000μm; The size of the first overlapping section printed portion in the fifth direction is 15μm to 60μm; The minimum dimension of the printed portion of the second overlapping section in the fifth direction is 10μm to 30μm.

19. The printing screen assembly according to claim 16, characterized in that, The width of the busbar printed hole is greater than the width of the interconnect gate printed hole.

20. The printing screen assembly according to claim 19, characterized in that, The width of the printed holes in the busbar is 15μm to 40μm; And / or, the width of the interconnect gate printed aperture is 10μm to 30μm.

21. The printing screen assembly according to any one of claims 16 to 20, characterized in that, The busbar printing hole is forked at least one end to have two branch segment printing portions, the two branch segment printing portions are spaced apart in the sixth direction, and each branch segment printing portion is configured to print a branch segment of the busbar. And / or, the busbar printing hole is further provided with a welding part printing hole, the welding part printing hole is arranged on the busbar to print the welding part; And / or, the fifth direction and the sixth direction are perpendicular.

22. The printing screen assembly according to any one of claims 15 to 20, characterized in that, Multiple collector grid printed holes are arranged at intervals along the fourth direction to form a column, and multiple columns of collector grid printed holes are arranged along the third direction; In two adjacent columns of the current collector grid printed holes, one column of the current collector grid printed holes is a first side grid printed hole, and the other column of the current collector grid printed holes is a second side grid printed hole. In the fourth direction, the first side grid printed holes and the second side grid printed holes are alternately arranged, and any first side grid printed hole and an adjacent second side grid printed hole form a pair of current collector grid printed holes.

23. The printing screen assembly according to claim 22, characterized in that, In the same column of the current collector wire printed holes, multiple current collector wire printed holes are arranged at equal intervals; And / or, in the fourth direction, the spacing between each of the first side gate line printed holes in two adjacent columns of the collector grid line printed holes and the adjacent second side gate line printed holes is equal.

24. The printing screen assembly according to claim 22, characterized in that, In the same column of the printed holes for the current collector lines, the spacing between two adjacent printed holes for the current collector lines is 0.6 mm to 1.4 mm; And / or, in the fourth direction, the distance between each of the first side grid line printed holes in two adjacent columns of the current collector grid line printed holes and the adjacent second side grid line printed holes is 0.3mm to 0.7mm.

25. The printing screen assembly according to any one of claims 15 to 20, characterized in that, The length of a single printed section of the connecting segment is 0.5% to 10% of the length of a single printed hole of the current collector wire.

26. The printing screen assembly according to claim 25, characterized in that, The width of the printed holes for the current collector grid is 5μm to 15μm; And / or, the length of the printed holes of the current collector grid is 5mm to 15mm; And / or, the length of the printed portion of the connecting section is 0.03mm to 0.5mm; And / or, the second printing screen is a metal film printing screen; And / or, the third direction is perpendicular to the fourth direction.

27. A photovoltaic module, characterized in that, It includes a plurality of solar cells connected in series and / or in parallel, at least one of the solar cells being the solar cell of any one of claims 1 to 14, or at least one of the solar cells being made using a printing screen assembly of any one of claims 15 to 26.

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