A solar cell, a printing screen assembly, and a photovoltaic assembly

Abstract

The application relates to the technical field of solar cells, in particular to a solar cell, a printing screen assembly and a photovoltaic module. The solar cell comprises a cell body, a plurality of busbar lines and a plurality of current collecting grid lines. Each busbar line is arranged on the surface of the cell body, and the length direction of the busbar line is a first direction. Each current collecting grid line is arranged on the surface of the cell body and extends along a second direction, and the second direction intersects the first direction. Two current collecting grid lines are arranged in the second direction to form a pair. In at least one pair of current collecting grid lines, the two current collecting grid lines are staggered in the first direction and the second direction, and in the second direction, the two current collecting grid lines are respectively provided with overlapping structures at the ends close to each other, and the two overlapping structures are staggered in the first direction and intersect the same busbar line. The overlapping structure of the solar cell is wider and higher than the current collecting grid line, so that the current collecting grid line is not easy to be welded off during welding, thereby reducing the phenomenon of broken grid of the current collecting grid line.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and more particularly to a solar cell, a printed screen module, and a photovoltaic module. Background Technology

[0002] There is still room for improvement in the conversion efficiency of solar cells. One of the current directions for improving the conversion efficiency of solar cells in the photovoltaic industry is to focus on the optimization of electrode grid pattern. However, how to further optimize the design of electrode pattern based on the current industrialization process capability is a problem that needs to be solved by those skilled in the art. Utility Model Content

[0003] This application discloses a solar cell, a printed screen assembly, and a photovoltaic module. The solar cell can improve efficiency by printing narrower linewidth collector grids using a high aperture ratio printed screen, and can also reduce grid breakage. This results in better current collection of the solar cell and improves its conversion efficiency.

[0004] To achieve the above objectives, in a first aspect, embodiments of this application disclose a solar cell, comprising:

[0005] Battery body;

[0006] A plurality of busbars, each of the busbars being disposed on the surface of the battery body, wherein the length direction of the busbars is a first direction; and

[0007] Multiple current collector grid lines are disposed on the surface of the battery body and extend along a second direction, which intersects with the first direction; two current collector grid lines are arranged in the second direction to form a pair.

[0008] In at least one pair of current collector grid lines, the two current collector grid lines are staggered in both the first direction and the second direction. In the second direction, the ends of the two current collector grid lines close to each other are respectively provided with overlapping structures. The two overlapping structures are staggered in the first direction and intersect with the same current collector grid line. The widest part of at least one overlapping structure is wider than the width of the current collector grid line in the first direction, and the highest point of this overlapping structure in the thickness direction of the battery body is also higher than the current collector grid line.

[0009] In a possible implementation of the first aspect, at least one of the overlapping structures on a pair of said collector grid lines passes through the bus grid line along the second direction.

[0010] In one possible implementation of the first aspect, the overlapping structure includes a first overlapping substructure and a second overlapping substructure, wherein the first overlapping substructure is integrally formed with the current collector grid line, the second overlapping substructure is integrally formed with the current bus grid line, and the first overlapping substructure is stacked on the side of the second overlapping substructure opposite to the battery body.

[0011] In one possible implementation of the first aspect, the length of the first overlapping substructure in the second direction is greater than the length of the second overlapping substructure in the second direction;

[0012] And / or, the width of the widest part of the second overlapping substructure in the first direction is greater than the width of the widest part of the first overlapping substructure in the first direction.

[0013] In a possible implementation of the first aspect, the overlapping structure has an extension segment that is part of the first overlapping substructure; or, the extension segment is part of the second overlapping structure.

[0014] When the extension is part of the first overlap substructure, the first overlap substructure passes through the busbar along the second direction, the extension is the portion of the first overlap substructure that protrudes from the busbar, and the extension is located at the end of the first overlap substructure away from the connected collector grid.

[0015] When the extension is part of the second overlap substructure, the second overlap substructure passes through the busbar along the second direction, the extension is the portion of the second overlap substructure that protrudes from the busbar, and the extension is located at one end of the second overlap substructure away from the connected collector busbar.

[0016] In a possible implementation of the first aspect, each of the first overlapping substructures extends along the second direction and includes a first narrowing segment and a first overlapping segment connected end to end;

[0017] The first overlap segment intersects with the busbar, and the width of the first overlap segment in the first direction is greater than the width of the collector busbar;

[0018] The first narrowing segment is connected between the first overlapping segment and the collector grid line. The width of the first narrowing segment in the first direction narrows away from the first overlapping segment, and the width of the widest part of the first narrowing segment is greater than the width of the collector grid line.

[0019] When the extension is part of the first overlap substructure, the extension is connected to the end of the first overlap away from the first narrowing section, and the extension protrudes from the busbar on the side away from the first narrowing section; the dimension of the extension in the first direction is the width of the extension, wherein the width of the extension narrows in the direction away from the first overlap; or, the width of the extension is equal to the width of the first overlap; or, the width of the extension is equal to the width of the collector wire.

[0020] In a possible implementation of the first aspect, each of the second overlapping substructures extends along the second direction and includes a second overlapping segment and a second narrowing segment connected end to end;

[0021] One end of the second overlapping section in the second direction intersects with the busbar, and the width of the second overlapping section in the first direction is greater than the width of the collector grid.

[0022] The second narrowing segment is connected between the second overlapping segment and the collector grid line. The width of the second narrowing segment in the first direction narrows away from the second overlapping segment, and the width of the widest part of the second narrowing segment is greater than the width of the collector grid line.

[0023] The first narrowing segment is stacked on the side of the second narrowing segment opposite to the battery body, and the first overlapping segment is stacked on the side of the second overlapping segment opposite to the battery body.

[0024] In a possible implementation of the first aspect, the height of the overlapping structure at its highest point in the thickness direction of the battery body is H1, the height of the current collector grid line is H2, and H1 / H2≥1.1;

[0025] The width of the widest part of the overlapping structure in the first direction is W1, and the width of the collector grid line is W2, where W1 / W2 = 1.01 to 10.

[0026] In a possible implementation of the first aspect, the height H1 of the highest point of the overlapping structure in the thickness direction of the battery body is 7 μm to 10.5 μm; the height H2 of the current collector grid line is 2 μm to 8 μm.

[0027] And / or, the width W1 of the widest part of the overlapping structure in the first direction is 50μm to 100μm, and the width W2 of the collector grid line is 10μm to 20μm.

[0028] In a possible implementation of the first aspect, multiple collector grid lines are arranged in a row at intervals along the first direction, and multiple rows of collector grid lines are arranged along the second direction, with two adjacent rows of collector grid lines overlapping the same busbar.

[0029] 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 lines and the second side grid lines are alternately arranged, and any first side grid line and an adjacent second side grid line form a pair of collector grid lines.

[0030] In one possible implementation of the first aspect, the multiple busbars are equidistantly arranged in the second direction;

[0031] And / or, in the same column of collector grid lines, multiple collector grid lines are arranged at equal intervals;

[0032] 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.

[0033] In a possible implementation of the first aspect, the battery body includes a silicon substrate, a doped layer, and a first functional film. The doped layer and the first functional film are disposed on the front side of the silicon substrate in a direction away from the silicon substrate. Each of the current collector grid lines is disposed on the first functional film and passes through the first functional film to make ohmic contact with the doped layer. Each of the current bus grid lines is disposed on the side of the first functional film away from the silicon substrate.

[0034] And / or, the first direction is perpendicular to the second direction.

[0035] Secondly, embodiments of this application disclose a printing screen assembly for a solar cell as described in the first aspect, comprising:

[0036] A first printing screen is provided with a plurality of current collector line printing slots, the opening ratio of the current collector line printing slots being 90% to 100%; the length direction of the current collector line printing slots is a third direction; two current collector line printing slots are arranged in the third direction to form a pair; in at least one pair of current collector line printing slots, the two current collector line printing slots are staggered in the third direction and the fourth direction, the fourth direction intersecting the third direction, in the third direction, the two current collector line printing slots are respectively provided with a first overlapping printing slot at their ends close to each other, the two first overlapping printing slots are at least partially arranged opposite each other in the fourth direction, and the width of the widest part of at least one first overlapping printing slot in the fourth direction is greater than the width of the current collector line printing slot;

[0037] The second printing screen has a plurality of busbar printing grooves. The length direction of the busbar printing grooves is the fifth direction. The busbar printing grooves have a plurality of second overlapping printing grooves spaced apart along the fifth direction. Each second overlapping printing groove extends along the sixth direction and protrudes from the busbar printing groove. The sixth direction intersects with the fifth direction.

[0038] In a possible implementation of the second aspect, each of the first overlapping printing grooves includes a first narrowing groove segment and a first overlapping groove segment; in the third aspect, the current collector wire printing groove, the first narrowing groove segment and the first overlapping groove segment are connected end to end in sequence;

[0039] Wherein, the width of the first narrowing groove segment in the fourth direction narrows away from the first overlapping groove segment, and the width of the widest part of the first narrowing groove segment is greater than the width of the current collector wire printing groove.

[0040] The width of the first overlapping groove segment in the fourth direction is greater than the width of the current collector wire printing groove.

[0041] In a possible implementation of the second aspect, the first overlapping printing groove further includes an extension groove segment connected to the end of the first overlapping groove segment away from the first narrowing groove segment; the dimension of the extension groove segment in the fourth direction is the width of the extension groove segment; wherein the width of the extension groove segment narrows in the direction away from the first overlapping groove segment; or, the width of the extension groove segment is equal to the width of the first overlapping groove segment; or, the width of the extension groove segment is equal to the width of the current collector line printing groove.

[0042] In a possible implementation of the second aspect, each of the second overlapping printing grooves includes a second overlapping groove segment and a second narrowing groove segment, the second overlapping groove segment extending along the sixth direction, and one end of the second overlapping groove segment in the sixth direction intersecting the busbar line, the second narrowing groove segment being connected to the end of the second overlapping groove segment away from the busbar line and extending in the same direction as the second overlapping groove segment;

[0043] Wherein, the width of the second narrowing groove segment in the fifth direction narrows away from the second overlapping groove segment, and the width of the widest part of the second narrowing groove segment is greater than the width of the current collector wire printing groove; the width of the second overlapping groove segment in the fifth direction is greater than the width of the current collector wire printing groove.

[0044] In a possible implementation of the second aspect, a plurality of the current collector wire printing slots are arranged at intervals along the fourth direction to form a column, and multiple columns of the current collector wire printing slots are arranged along the third direction;

[0045] In two adjacent columns of the current collector grid lines, one column of the current collector grid lines is a first side grid line printing groove, and the other column of the current collector grid lines is a second side grid line printing groove. In the fourth direction, the first side grid line printing groove and the second side grid line printing groove are alternately arranged, and any first side grid line printing groove and an adjacent second side grid line printing groove form a pair of current collector grid lines printing grooves.

[0046] The fourth direction is perpendicular to the third direction.

[0047] In a possible implementation of the second aspect, multiple current collector wire printing slots are arranged at equal intervals in the same column of current collector wire printing slots;

[0048] And / or, in the fourth direction, the spacing between each of the first side grid line printing slots in two adjacent columns of the current collector grid line printing slots and the adjacent second side grid line printing slots is equal.

[0049] In a possible implementation of the second aspect, a plurality of second overlapping printing grooves are alternately arranged on two opposite sides of the busbar printing groove in the sixth direction, and each of the second overlapping printing grooves protrudes in a direction away from the busbar printing groove.

[0050] And / or, the number of the busbar printing slots is multiple, and the multiple busbar printing slots are spaced apart along the sixth direction;

[0051] And / or, the sixth direction is perpendicular to the fifth direction.

[0052] Thirdly, embodiments of this application disclose a photovoltaic module, including a plurality of solar cells connected in series and / or in parallel, wherein at least one of the solar cells is the solar cell described in the first aspect, or at least one of the solar cells is a solar cell made of the screen printing plate assembly described in the second aspect.

[0053] Compared with the prior art, the beneficial effects of this application include at least the following:

[0054] This solar cell, by optimizing the grid pattern, facilitates improved efficiency through printing narrower linewidth collector grids using a high aperture ratio printing screen. It also extends the lifespan and improves the printing quality of the high aperture ratio printing screen. Furthermore, the solar cell incorporates a wider and taller overlap structure at the intersection of the collector grid and the busbar grid. This overlap structure is less prone to breakage during welding, reducing grid breakage and resulting in better current collection, thus enhancing the solar cell's conversion efficiency.

[0055] Specifically, regarding the optimization of the grid pattern, in at least one pair of collector grids of this solar cell, the two collector grids are staggered in both the first and second directions, and the ends of these two collector grids closest to each other are respectively connected to the same busbar via an overlapping structure. Therefore, the current collection range of a pair of collector grids is equivalent to the distance between the two ends of this pair of collector grids in the second direction. In other words, in order to collect current from the surface of a cell of a certain size, related technologies use a single, continuous, and relatively long collector grid for current collection, while the solar cell of this application utilizes two discontinuous, and relatively short, collector grids combined together for current collection.

[0056] To improve the conversion efficiency of solar cells, this application utilizes a high aperture ratio printing screen to print narrower linewidth collector grids, thereby reducing the shading area of ​​the collector grids. Since the collector grids in this application are shorter, the length of the collector grid printing grooves is correspondingly shorter. The structural strength of the high aperture ratio printing screen is negatively correlated with the length of the collector grid printing grooves; that is, the shorter the length of the collector grid printing grooves, the stronger the structural strength of the high aperture ratio printing screen. Furthermore, the shorter the collector grid printing grooves, the smaller the deformation of the collector grid printing grooves during printing, thus reducing printing misalignment and excessively thick grid lines caused by the deformation of the collector grid printing grooves.

[0057] To prevent the current collector grid lines from breaking off from the busbars during welding, at least one pair of current collector grid lines has an overlapping structure at their ends closest to each other. These two overlapping structures are staggered in a first direction and intersect the same busbar. The widest point of at least one overlapping structure in the first direction is wider than the width of the current collector grid line, and the highest point of this overlapping structure in the thickness direction of the battery body is also higher than the current collector grid line. It is understood that the welding performance of the overlapping structure is positively correlated with its width and height. A higher width and height indicate a higher material content (e.g., silver), which helps the overlapping structure resist the silver etching reaction of the solder ribbon during welding, reducing the likelihood of grid breakage. In other words, providing a wider and higher overlapping structure at the intersection of the current collector grid line and the busbar improves the welding performance at the connection point, reducing the likelihood of grid breakage during welding and thus enhancing the connection between the current collector grid line and the busbar. If the current in the collector grid can be successfully collected into the bus grid, the current collection effect of the solar cell will be better, which will help improve the conversion efficiency of the solar cell. Attached Figure Description

[0058] 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.

[0059] Figure 1 This is a schematic diagram of the structure of a solar cell disclosed in an embodiment of this application;

[0060] Figure 2 for Figure 1 A magnified view of a portion of region I shown in the diagram;

[0061] Figure 3 for Figure 2 The AA cross-section shown in the figure;

[0062] Figure 4 for Figure 2 The BB cross-section shown in the figure;

[0063] Figure 5 for Figure 1 A magnified view of a portion of region II shown in the diagram;

[0064] Figure 6 This is a schematic diagram of the structure of a printing screen assembly disclosed in an embodiment of this application;

[0065] Figure 7 This is a schematic diagram of the structure of the first printing screen disclosed in the embodiments of this application;

[0066] Figure 8 for Figure 7 A magnified view of a portion of region III shown in the diagram;

[0067] Figure 9 for Figure 7 A magnified view of region IV shown in the diagram;

[0068] Figure 10 This is a schematic diagram of the structure of the second printing screen disclosed in an embodiment of this application.

[0069] Explanation of reference numerals in the attached figures:

[0070] 10. Solar cell; 11. Cell body; 111. Silicon substrate; 112. Doped layer; 113. First functional film; 114. Interface passivation layer; 115. Doped polycrystalline silicon layer; 116. Second functional film; 12. Busbar; 13. Current collector; 13a. First side busbar; 13b. Second side busbar; 14. Overlap structure; 141. First overlap substructure; 1411. Extension segment; 1412. First overlap segment; 1413. First narrowing segment; 142. Second overlap substructure; 1421. Second overlap segment; 1422. Second narrowing segment; Y1. First direction; X1. Second direction; Z. Thickness direction of the cell body;

[0071] 20. First printing screen; 21. Collector grid line printing groove; 21a. First side grid line printing groove; 21b. Second side grid line printing groove; 22. First overlapping printing groove; 221. First narrowing groove segment; 222. First overlapping groove segment; 223. Extension groove segment; X2. Third direction; Y2. Fourth direction;

[0072] 30. Second printing screen; 31. Busbar printing groove; 32. Second overlapping printing groove; 321. Second overlapping groove segment; 322. Second narrowing groove segment; Y3. Fifth direction; X3. Sixth direction. Detailed Implementation

[0073] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0074] In this application, the terms "set up," "equipped with," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0075] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0076] One way to improve the conversion efficiency of solar cells is to narrow the linewidth of the current collector grid, thereby reducing the overall shading area of ​​the current collector grid and the wet weight of the printing paste. A reduced shading area allows the solar cell to absorb more light, thus improving its conversion efficiency.

[0077] Narrow-line-width collector grids are difficult to print using wire mesh printing because: wire mesh printing is made of woven steel wire. Therefore, steel wires are present in the printing slots of the wire mesh, limiting the opening rate to only 80%. The presence of steel wires in the printing slots affects the transmission of the printing paste. When wire mesh is used to print narrow collector grids, poor paste transmission leads to printing abnormalities and poor grid morphology. In other words, wire mesh printing is not suitable for printing narrow-line-width collector grids, which hinders the improvement of conversion efficiency in solar cells by narrowing the collector grid linewidth.

[0078] High aperture ratio printing screens are more suitable for printing narrower current collector lines. This is because such screens leave almost no material residue in the opening area when creating the opening, while wire mesh screens only remove some material but retain the wires in the opening area. In other words, the aperture ratio of a high aperture ratio printing tank is higher than that of a wire mesh screen, reaching 90%–100% (including endpoint values). More specifically, in this application, the aperture ratio can be measured using a screen inspection instrument. High aperture ratio printing tanks have very little or no obstruction. The ink experiences less resistance as it passes through the printing tank, resulting in good ink permeability. However, due to the high aperture ratio, the internal structure lacks wires or other reinforcement for stretching and structural enhancement. Understandably, when the printing tank is too long, the structural strength of the high aperture ratio printing screen will be 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 groove for printing the straight current collector lines is also a straight opening with a length comparable to the size of the printing screen. An excessively long printing groove will reduce the structural strength of the printing screen. On the other hand, since there is a lack of steel wires for tension in high-aperture printing screens, when the squeegee applies force on the high-aperture printing screen, the printing groove is prone to deformation, resulting in positional changes and widening of the opening. This leads to printing abnormalities such as printing misalignment and coarse grids, and these printing abnormalities increase and worsen with the increase of the printing groove length.

[0079] The inventors discovered that the current collector lines of solar cells can be designed as discontinuous lines to shorten their length. More specifically, by combining multiple discontinuous, shorter current collector lines, a similar current collection effect to that of longer current collector lines can be achieved. The shorter length of the discontinuous current collector lines correspondingly results in a shorter printing groove. Based on this analysis, shorter current collector lines are beneficial for improving the structural strength of the printing screen and reducing printing defects.

[0080] However, if the overlapping portion of the discontinuous collector grid line overlaps the busbar, since the overlapping portion is part of the collector grid line, and the linewidth and height of the collector grid line are relatively narrow, the material (including silver) of the overlapping portion is relatively thin. During soldering of the solder ribbon to the busbar, the solder ribbon may come into contact with the overlapping portion of the collector grid line. The silver etching reaction caused by the solder ribbon during soldering may cause all the silver in the overlapping portion to be reacted, leading to a break in the grid between the collector grid line and the busbar. When the connection between the collector grid line and the busbar is broken, the current collected by this collector grid line cannot be collected by the busbar. Therefore, even if the shading area is reduced by printing a narrower linewidth collector grid line, the conversion efficiency of the solar cell cannot be effectively improved due to the deteriorated current collection effect.

[0081] Based on the above analysis, this solar cell, by optimizing the grid pattern, facilitates improved efficiency by printing narrower collector grid lines using a high aperture ratio printing screen. It also extends the lifespan and printing quality of the high aperture ratio printing screen. Furthermore, the solar cell incorporates a wider and taller overlap structure at the intersection of the collector grid lines and the busbar grid lines. This overlap structure is less prone to breakage during welding, reducing grid breakage and resulting in better current collection, thus improving the solar cell's conversion efficiency.

[0082] The technical solution of this utility model will be described below with reference to the embodiments and accompanying drawings.

[0083] Firstly, such as Figures 1 to 3 As shown in the figure, this application discloses a solar cell 10, including a cell body 11, a plurality of busbars 12 and a plurality of collector grids 13.

[0084] Each busbar 12 is disposed on the surface of the battery body 11, and the length direction of the busbar 12 is the first direction Y1.

[0085] Each current collector grid line 13 is disposed on the surface of the battery body 11 and extends along the second direction X1, which intersects the first direction Y1. Two current collector grid lines 13 are arranged in the second direction X1 to form a pair.

[0086] In at least one pair of current collector grid lines 13, the two current collector grid lines 13 are staggered in the first direction Y1 and the second direction X1. In the second direction X1, the two current collector grid lines 13 are respectively provided with overlapping structures 14 at their ends close to each other. The two overlapping structures 14 are staggered in the first direction Y1 and intersect with the same current collector grid line 12. The widest part of at least one overlapping structure 14 is wider than the width of the current collector grid line 13 in the first direction Y1, and the highest point of this overlapping structure 14 in the thickness direction Z of the battery body is also higher than the current collector grid line 13.

[0087] By optimizing the grid pattern, the solar cell 10 can improve efficiency by printing narrower collector grid lines 13 using a high aperture ratio printing screen. This also extends the lifespan and improves the printing quality of the high aperture ratio printing screen. Furthermore, the solar cell 10 incorporates a wider and higher overlap structure 14 at the intersection of the collector grid lines 13 and the busbar lines 12. This overlap structure 14 is less prone to breakage during welding, reducing grid breakage and improving the current collection efficiency of the solar cell 10.

[0088] Specifically, regarding the optimization of the grid pattern, in the solar cell 10, at least one pair of collector grid lines 13 are staggered in both the first direction Y1 and the second direction X1, and the ends of these two collector grid lines 13 closest to each other are respectively connected to the same busbar 12 via an overlapping structure 14. Therefore, the current collection range of a pair of collector grid lines 13 is equivalent to the distance between the two ends of this pair of collector grid lines 13 in the second direction X1. In other words, in order to collect current from the surface of a cell body 11 of a certain size, related technologies use a single continuous, long collector grid line 13 for current collection, while the solar cell 10 of this application utilizes two discontinuous, shorter collector grid lines 13 combined together for current collection.

[0089] To improve the conversion efficiency of the solar cell 10, this application uses a high aperture ratio printing screen to print narrower linewidth collector grid lines 13, thereby reducing the light-shielding area of ​​the collector grid lines 13. Since the collector grid lines 13 in this application are shorter, the length of the collector grid line printing groove is also shorter. The structural strength of the high aperture ratio printing screen is negatively correlated with the length of the collector grid line printing groove; that is, the shorter the length of the collector grid line printing groove, the stronger the structural strength of the high aperture ratio printing screen and the longer its service life. Furthermore, the shorter the collector grid line printing groove, the smaller the deformation of the collector grid line printing groove during printing, thereby reducing printing offset and excessively thick grid lines caused by the deformation of the collector grid line printing groove.

[0090] To prevent the current collector grid line 13 from breaking off from the bus grid line 12 during welding, at least one pair of current collector grid lines 13 has an overlap structure 14 at one end closest to each other. These two overlap structures 14 are staggered in the first direction Y1 and intersect the same bus grid line 12. The widest part of at least one overlap structure 14 in the first direction Y1 is wider than the width of the current collector grid line 13, and the highest point of this overlap structure 14 in the thickness direction Z of the battery body is also higher than the current collector grid line 13. It is understood that the welding performance of the overlap structure 14 is positively correlated with its width and height. A higher width and height of the overlap structure 14 indicates a higher content of material (e.g., silver). During welding, the overlap structure 14 can resist the silver etching reaction of the solder ribbon and is less prone to grid breakage. In this application, "silver etching reaction" refers to the reaction between the tin-based alloy on the surface of the solder ribbon and the silver in the electrode material to be welded, thereby reducing the silver content in the electrode material that is used for current transmission.

[0091] In other words, by setting a wider and taller overlap structure 14 at the intersection of the collector grid 13 and the bus grid 12, which is wider and taller than the collector grid 13, the welding performance at the connection between the collector grid 13 and the bus grid 12 can be improved. This reduces the likelihood of grid breakage during welding, thereby enhancing the connection effect between the collector grid 13 and the bus grid 12. Since the current from the collector grid 13 can be smoothly collected into the bus grid 12, the current collection effect of the solar cell 10 is better, which is beneficial to improving the conversion efficiency of the solar cell 10.

[0092] The overlapping structure will be explained in detail below.

[0093] In the embodiments of this application, reference is made to Figure 2 At least one overlapping structure 14 on a pair of collector grid lines 13 passes through the bus grid line 12 along the second direction X1. It should be noted that the term "passes through" means that the overlapping structure 14 passes through both sides of the bus grid line 12 along the second direction X1, with both ends of the overlapping structure 14 protruding from the bus grid line 12, forming a cross-shaped structure or an X-shaped structure. More specifically, "at least one overlapping structure 14 on a pair of collector grid lines 13 passes through the bus grid line 12 along the second direction X1" means that one overlapping structure on the pair of collector grid lines passes through the bus grid line along the second direction; or, as... Figure 2 As shown, the two overlapping structures 14 on a pair of collector grid lines 13 both pass through the bus grid line 12 along the second direction X1.

[0094] Optionally, the first direction Y1 and the second direction X1 are perpendicular. Of course, the angle between the first direction Y1 and the second direction X1 can deviate slightly from 90°, for example, it can be 80°, 85°, 89°, 91° or 95°, and this embodiment of the application does not limit this.

[0095] When the overlap structure 14 passes through the busbar 12 along the second direction X1, even if the solder strip is misaligned before welding, it can still contact the two protruding portions of the overlap structure 14 after it passes through both sides of the busbar 12. In other words, the above design provides leeway for solder strip alignment offset, thereby improving the welding effect of the solar cell 10.

[0096] See Figure 3 In this application, the height of the highest point of the overlapping structure 14 in the thickness direction of the battery body 11 is H1, and the height of the current collector grid line 13 is H2, where H1 / H2 ≥ 1.1, for example, H1 / H2 = 1.1, 1.5, 2, or 2.5. When the height H1 of the highest point of the overlapping structure 14 meets the above ratio range, the height of the highest point of the overlapping structure 14 is higher than that of the current collector grid line 13, which can effectively block the silver etching reaction during soldering and also achieve a lower wet weight of the paste during printing.

[0097] It should be noted that when measuring the height of the overlapping structure 14 and the collector grid line 13 using a 3D microscope, the height measurement baseline is selected by the 3D microscope's built-in testing algorithm. This is understandable. Figure 3 The altitude measurement baseline shown is only for illustration and does not restrict the altitude measurement baseline to this location.

[0098] Optionally, the width of the widest part of the overlap structure 14 in the first direction Y1 is W1, and the width of the collector grid line 13 is W2, where W1 / W2 = 1.01 to 10, for example, W1 / W2 = 1.01, 3, 5, 7, 9, or 10. When the width of the widest part of the overlap structure 14, W1, satisfies the above ratio range, the width of the widest part of the overlap structure 14 is sufficiently wide to effectively block the silver etching reaction during soldering, while also having a low light-shielding area and low resistance, and also having a low wet weight of the paste during printing.

[0099] Optionally, the height H1 of the highest point of the overlap structure 14 in the thickness direction of the battery body 11 is 7μm to 10.5μm, for example, 7μm, 8μm, 9μm, 10μm or 10.5μm. When the height H1 of the highest point of the overlap structure 14 meets the above numerical range, in terms of welding performance, the overlap structure 14 has a sufficiently thick material layer in the thickness direction of the battery body 11, so that the overlap structure 14 can effectively block the silver etching reaction during soldering; in terms of electrical characteristics, the overlap structure 14 has a large cross-sectional area and thus has low resistance; in terms of printing cost, the overlap structure 14 has a low wet weight of paste during printing by avoiding excessive height.

[0100] Optionally, the width W1 of the widest point of the overlap structure 14 in the first direction Y1 is 50μm to 100μm, for example, 50μm, 60μm, 70μm, 80μm, 90μm, or 100μm. When the width W1 of the widest point of the overlap structure 14 meets the numerical range, in terms of welding performance, the overlap structure 14 has a sufficiently wide material layer in the first direction Y1, and the overlap structure 14 can effectively block the silver etching reaction during solder ribbon welding; in terms of electrical characteristics, the overlap structure 14 has a large cross-sectional area and low resistance; in terms of printing cost, the overlap structure 14 has a low wet weight of paste during printing by avoiding excessive width; in terms of light-shielding area, the overlap structure 14 has a small light-shielding area by avoiding excessive width.

[0101] In some embodiments, referencing the back Figure 2 and Figure 3 The overlapping structure 14 includes a first overlapping substructure 141 and a second overlapping substructure 142. The first overlapping substructure 141 is integrally formed with the current collector grid line 13, and the second overlapping substructure 142 is integrally formed with the current collector grid line 12. The first overlapping substructure 141 is stacked on the side of the second overlapping substructure 142 away from the battery body 11.

[0102] For example, during the printing stage, the first overlap structure 141 is printed together with the collector grid line 13 and integrally formed, while the second overlap structure 142 is printed together with the bus grid line 12 and integrally formed.

[0103] This application allows the overlapping structure 14 to be obtained without adding additional printing steps. For example, the second overlapping substructure 142 is printed simultaneously during the busbar 12 printing stage, and then the first overlapping substructure 141 is printed simultaneously during the collector busbar 13 printing stage. Since the height of the first overlapping substructure 141 is equal to or not significantly different from the height of the collector busbar 13, the height at the overlap between the first overlapping substructure 141 and the second overlapping substructure 142 can be higher than that of the collector busbar 13. In other words, an overlapping structure 14 higher than that of the collector busbar 13 is obtained through two printing steps.

[0104] Of course, the overlapping structure 14 can be obtained by printing with a printing screen in one step. That is to say, the overlapping structure 14 does not necessarily have to include two parts (the first overlapping substructure 141 and the second overlapping substructure 142). For example, related technologies can also directly print an overlapping structure 14 that is taller and wider than the collector grid line 13 while printing the collector grid line 13.

[0105] It should be noted that, in Figure 3In the cross-sectional view of the first overlapping substructure 141 and the second overlapping substructure 142, the top surface is a plane. However, the top surface of the cross-sectional view of the first overlapping substructure and the second overlapping substructure can also be an arc surface, a curved surface, or other surfaces. This application embodiment does not limit this.

[0106] To allow for the printing alignment process of the first overlapping substructure 141, such as Figure 2 As shown in the embodiment of this application, the length of the first overlap structure 141 in the second direction X1 is greater than the length of the second overlap structure 142 in the second direction X1. If the first overlap structure 141 is offset in the second direction X1 and the offset is within the allowable range, the various positions of the second overlap structure 142 in the second direction X1 can still be stacked with the first overlap structure 141 and be higher than the collector grid line 13, so that the overlap structure 14 has a strong ability to resist the silver etching reaction of the solder ribbon.

[0107] Furthermore, such as Figure 2 As shown, the widest part of the second overlap structure 142 in the first direction Y1 is wider than the widest part of the first overlap structure 141 in the first direction Y1. Thus, if the first overlap structure 141 shifts in the first direction Y1 and the shift is within the allowable range, each position of the first overlap structure 141 in the first direction Y1 can still overlap with the second overlap structure 142 and be higher than the collector grid line 13, making the overlap structure 14 more resistant to the silver etching reaction of the solder ribbon.

[0108] In some embodiments, such as Figure 2 As shown, the overlap structure 14 has an extension 1411, which is part of the first overlap substructure 141. Alternatively, the extension is part of the second overlap structure.

[0109] When the extension 1411 is part of the first overlap structure 141, the first overlap structure 141 passes through the busbar 12 along the second direction X1, the extension 1411 is the part of the first overlap structure 141 that protrudes from the busbar 12, and the extension 1411 is located at the end of the first overlap structure 141 away from the connected collector line 13.

[0110] When the extension is part of the second overlap substructure, the second overlap substructure passes through the busbar in the second direction, the extension is the part of the second overlap substructure that protrudes from the busbar, and the extension is located at the end of the second overlap substructure away from the connected collector busbar.

[0111] Understandably, the extension 1411 is the portion of the overlapping structure 14 that protrudes from the busbar 12 as it passes through the busbar 12 along the second direction X1. Specifically, the extension 1411 can be the portion of the first overlapping substructure 141 that protrudes from the busbar 12, such that the first overlapping substructure 141 passes through the busbar 12 to form a cross-shaped or X-shaped structure. Alternatively, the extension can be the portion of the second overlapping substructure that protrudes from the busbar, such that the second overlapping substructure passes through the busbar to form a cross-shaped or X-shaped structure.

[0112] Therefore, even if the solder strip is misaligned before welding, it can still contact the extension 1411. In other words, the extension 1411 provides leeway for solder strip alignment, thereby improving the welding effect of the solar cell 10.

[0113] In some embodiments, such as Figure 2 As shown, each first overlapping substructure 141 extends along the second direction X1 and includes a first narrowing section 1413 and a first overlapping section 1412 connected end to end.

[0114] The first overlap segment 1412 intersects with the busbar 12, and the width of the first overlap segment 1412 in the first direction Y1 is greater than the width of the collector busbar 13.

[0115] The first narrowing segment 1413 is connected between the first overlapping segment 1412 and the collector grid line 13. The width of the first narrowing segment 1413 in the first direction Y1 narrows in a direction away from the first overlapping segment 1412, and the width of the widest part of the first narrowing segment 1413 is greater than the width of the collector grid line 13.

[0116] Understandably, the width of the first overlapping section 1412 and the width at the widest point of the first narrowing section 1413 are greater than the width of the collector grid line 13, allowing the first overlapping section 1412 and the first narrowing section 1413 to better block the silver etching reaction of the solder ribbon relative to the collector grid line 13. The width of the first narrowing section 1413 narrows in the direction away from the first overlapping section 1412, that is, the first narrowing section 1413 reduces its light-blocking area and reduces the wet weight of the paste during printing by narrowing its width.

[0117] More specifically, the shape of the first overlapping segment 1412 can be rectangular, meaning that the width of the first overlapping segment 1412 is consistent throughout the second direction X1. The shape of the first narrowing segment 1413 can be trapezoidal, meaning that the width of the first narrowing segment 1413 gradually narrows. Of course, the narrowing of the width of the first narrowing segment 1413 can also be a stepped narrowing. Furthermore, the width of the widest part of the first narrowing segment 1413 is the same as the width of the first overlapping segment 1412, and the width of the narrowest part of the first narrowing segment 1413 can be equal to the width of the collector grid line 13.

[0118] Furthermore, such as Figure 2 As shown, when the extension 1411 is part of the first overlap substructure 141, the extension 1411 is connected to the end of the first overlap 1412 away from the first narrowing section 1413, and the extension 1411 protrudes from the side of the busbar 12 away from the first narrowing section 1413. The dimension of the extension 1411 in the first direction Y1 is the width of the extension 1411, wherein the width of the extension 1411 narrows in the direction away from the first overlap 1412; or, the width of the extension 1411 is equal to the width of the first overlap 1412; or, the width of the extension 1411 is equal to the width of the collector busbar 13.

[0119] In addition to the functions mentioned above, another function of the extension 1411 is to extend the length of the first overlapping substructure 141, making the first overlapping substructure 141 longer than the second overlapping substructure 142. As described above, this provides leeway for the printing alignment process of the first overlapping substructure 141.

[0120] It should be noted that the first lap joint may not include an extension section. In this case, the extension section is part of the second lap joint, as detailed below.

[0121] In some embodiments, such as Figure 2 As shown, each second overlapping substructure 142 extends along the second direction X1 and includes a second overlapping section 1421 and a second narrowing section 1422 that are connected end to end.

[0122] The second overlapping section 1421 intersects the busbar 12 at one end in the second direction X1, and the width of the second overlapping section 1421 in the first direction Y1 is greater than the width of the collector busbar 13.

[0123] The second narrowing segment 1422 connects the second overlapping segment 1421 and the collector grid line 13. The width of the second narrowing segment 1422 in the first direction Y1 narrows away from the second overlapping segment 1421, and the width of the widest part of the second narrowing segment 1422 is greater than the width of the collector grid line 13. Further, the width of the widest part of the second narrowing segment 1422 is equal to the width of the second overlapping segment 1421, and the width of the narrowest part of the second narrowing segment 1422 can be equal to the width of the collector grid line 13.

[0124] Understandably, the width of the second overlap section 1421 and the width at the widest point of the second narrowing section 1422 are greater than the width of the collector grid line 13, allowing the second overlap section 1421 and the second narrowing section 1422 to better block the silver etching reaction of the solder ribbon relative to the collector grid line 13. The width of the second narrowing section 1422 narrows in a direction away from the first overlap section 1412, that is, the second narrowing section 1422 reduces its light-blocking area and reduces the wet weight of the paste during printing by narrowing its width.

[0125] Furthermore, the first narrowing segment 1413 is stacked on the side of the second narrowing segment 1422 away from the battery body, and the first overlapping segment 1412 is stacked on the side of the second overlapping segment 1421 away from the battery body, so that the first overlapping substructure 141 and the second overlapping substructure 142 are stacked in a pattern matching manner. On the one hand, this makes most of the overlapping structure 14 a stacked area with a height higher than the current collector grid line 13, thereby improving the ability of the overlapping structure 14 to block the silver etching reaction of the solder ribbon. On the other hand, it makes the overall electrode pattern of the solar cell 10 more aesthetically pleasing.

[0126] More in detail, such as Figure 2 As shown, the second overlapping segment 1421 can be rectangular, meaning that the width of the second overlapping segment 1421 is consistent throughout the second direction X1. The second narrowing segment 1422 can be trapezoidal, meaning that the width of the second narrowing segment 1422 gradually narrows. Of course, the narrowing of the width of the second narrowing segment 1422 can also be a stepped narrowing. Furthermore, the width of the widest part of the second narrowing segment 1422 is the same as the width of the second overlapping segment 1421, and the width of the narrowest part of the second narrowing segment 1422 can be equal to the width of the collector grid line 13.

[0127] Specifically, when the extension is part of the second overlap substructure, the extension connects to the end of the second overlap away from the second narrowing section, and the extension protrudes from the busbar on the side opposite to the second narrowing section. The function of the extension has been explained in detail above and will not be repeated here.

[0128] The battery itself will be described in detail below.

[0129] In some embodiments, such as Figure 3 and Figure 4 As shown, the battery body 11 includes a silicon substrate 111, a doped layer 112, and a first functional film 113. The doped layer 112 and the first functional film 113 are disposed on the front side of the silicon substrate 111 in a direction away from the silicon substrate 111. Each current collector grid line 13 is disposed on the first functional film 113 and passes through the first functional film 113 to make ohmic contact with the doped layer 112. Each current collector grid line 12 is disposed on the side of the first functional film 113 away from the silicon substrate 111.

[0130] As described above, by optimizing the grid pattern, the solar cell 10 can obtain a narrower linewidth collector grid line 13 through high aperture ratio screen printing. Placing this narrower linewidth collector grid line 13 on the front side of the silicon substrate 111 significantly reduces the light-shielding area of ​​the collector grid line 13 on the front side of the silicon substrate 111. Since the front side of the silicon substrate 111 is the light-receiving surface, reducing the light-shielding area of ​​the light-receiving surface effectively increases the light absorption of the solar cell 10, thereby improving the conversion efficiency of the solar cell 10.

[0131] Of course, the collector gate line 13 and the bus gate line 12 can also be disposed on the back side of the silicon substrate 111.

[0132] For example, the battery body 11 can be a passivated contact solar cell. The battery body 11 also includes an interface passivation layer 114, a doped polysilicon layer 115, and a second functional film 116. The interface passivation layer 114, the doped polysilicon layer 115, and the second functional film 116 are sequentially stacked on the back side of the silicon substrate 111 along a direction away from the silicon substrate 111. The conductivity type of the doped polysilicon layer 115 is opposite to that of the doped layer 112. When the current collector line 13 and the bus line 12 are disposed on the back side of the silicon substrate 111, the current collector line 13 passes through the second functional film 116 and makes ohmic contact with the doped polysilicon layer 115, and the bus line 12 is disposed on the side of the second functional film 116 away from the silicon substrate 111.

[0133] It should be noted that gate electrodes can also be provided on the side of the silicon substrate facing away from the aforementioned collector gate lines. For example, when the collector gate lines are provided on the front side of the silicon substrate, a back gate line can also be provided on the back side of the silicon substrate, and the back gate line can pass through the second functional film and make ohmic contact with the doped polycrystalline silicon layer.

[0134] Optionally, the silicon substrate 111 can be an N-type silicon substrate or a P-type silicon substrate. The doped layer 112 can be a diffusion layer, such as a boron diffusion layer or a phosphorus diffusion layer. The doped layer 112 can also be an N-type doped polycrystalline silicon layer or a P-type doped polycrystalline silicon layer. The first functional film 113 and the second functional film 116 can be passivation films and / or antireflection films. The materials of the first functional film 113 and the second functional film 116 can be silicon nitride, silicon oxynitride, silicon oxide, or aluminum oxide. The material of the interface passivation layer 114 can be at least one of silicon oxide, magnesium fluoride, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide.

[0135] As other examples, the battery body 11 can also be other types of crystalline silicon solar cells, such as heterojunction solar cells or back-contact solar cells.

[0136] Regarding the specifications of the battery body, the battery body can be a sliced ​​battery, such as a battery cut in half, or a whole battery.

[0137] The collector grid and the bus grid are described in detail below.

[0138] In some embodiments, such as Figure 5 As shown, multiple collector grid lines 13 are arranged in a row at intervals along the first direction Y1, and multiple rows of collector grid lines 13 are arranged along the second direction X1, with two adjacent rows of collector grid lines 13 overlapping the same busbar 12.

[0139] In two adjacent columns of collector grid lines 13, one column of collector grid lines 13 is a first side grid line 13a, and the other column of collector grid lines 13 is a second side grid line 13b. In the first direction Y1, the first side grid lines 13a and the second side grid lines 13b are alternately arranged, and any first side grid line 13a and an adjacent second side grid line 13b form a pair of collector grid lines 13. That is to say, the first side grid lines 13a and the second side grid lines 13b in the two columns of collector grid lines 13 form multiple pairs of collector grid lines 13.

[0140] In this embodiment of the application, by arranging multiple collector grid lines 13 in a row at intervals along the first direction Y1 so that the collector grid lines 13 are distributed in most areas of the battery body 11 in the first direction Y1, the current on the surface of the battery body 11 can be collected better.

[0141] To improve the strength of the printing screen, the current collector lines 13 are often shorter in the second direction X1. This ensures that the length of the current collector line printing grooves is short enough to avoid affecting the structural strength of the printing screen. In other words, one row of current collector lines 13 can only cover a small portion of the battery body 11 in the second direction X1. To distribute the current collector lines 13 over a large portion of the battery body 11 in the second direction X1, there are often more than two rows of current collector lines 13. To meet the current-carrying requirements of more than two rows of current collector lines 13, in this embodiment, multiple current-carrying grid lines 12 are equidistantly arranged in the second direction X1. The number of current-carrying grid lines 12 can be two, three, four, etc., and this embodiment does not limit this number.

[0142] For example, in the second direction X1, the Nth and N+1th collector grid lines 13 are both connected to the Nth bus grid line 12, the N+1th and N+2th collector grid lines 13 are both connected to the N+1th bus grid line 12, and so on.

[0143] Optionally, multiple collector grid lines 13 are arranged at equal intervals in the same column of collector grid lines 13. In other words, multiple collector grid lines 13 are evenly distributed in the same column of collector grid lines 13. In the area where this column of collector grid lines 13 is set, the current on the surface of the cell body 11 is evenly collected by this column of collector grid lines 13, and the situation of severe local shading can be avoided, so that the solar cell 10 receives light more evenly as a whole. The impact of the shading problem of the collector grid lines 13 on the performance of the solar cell 10 is minimized, thereby improving the conversion performance of the solar cell 10.

[0144] Furthermore, in two adjacent columns of collector grids 13, the spacing between each first side grid line 13a and the adjacent second side grid line 13b is equal in the first direction Y1. In other words, in two adjacent columns of collector grids 13, the first side grid lines 13a and the second side grid lines 13b are evenly distributed. In the area where these two columns of collector grids 13 are set, the current on the surface of the cell body 11 is evenly collected by these two columns of collector grids 13, and the situation of severe local shading can also be avoided, further improving the conversion performance of the solar cell 10.

[0145] Understandably, if the height of the collector grid line 13 is less than 4.5 μm, its cross-sectional area is small. Since the resistance of the grid electrode is inversely proportional to its cross-sectional area, the resistance of the collector grid line 13 will be relatively large. If the height of the collector grid line 13 is greater than 7 μm, the wet weight of the ink during printing will be relatively large. Optionally, the height H2 of the collector grid line 13 is 2 μm to 8 μm, for example, 2 μm, 4 μm, 6 μm, or 8 μm. When the collector grid line 13 meets the above height range, it has both low resistance and low wet weight of ink during printing.

[0146] Furthermore, if the width of the current collector line 13 is less than 10 μm, the cross-sectional area of ​​the current collector line 13 is small, resulting in a higher resistance. Additionally, the width of the printing groove used for printing the current collector line 13 is also narrow, which is detrimental to the passage of the printing paste, leading to a poorer morphology of the current collector line 13. If the width of the current collector line 13 is greater than 20 μm, the light-shielding area of ​​the current collector line 13 is large, and the wet weight of the printing paste will be larger. Optionally, the width W2 of the current collector line 13 is 10 μm to 20 μm, for example, 10 μm, 15 μm, or 20 μm. When the current collector line 13 meets the above width range, it has both lower resistance and light-shielding area, and can also achieve a lower wet weight of the printing paste, resulting in a better morphology after printing.

[0147] Secondly, such as Figures 6 to 10 As shown, this application discloses a printing screen assembly for a solar cell as described in the first aspect, including a first printing screen 20 and a second printing screen 30.

[0148] The first printing screen 20 has multiple collector line printing slots 21, and the opening ratio of the collector line printing slots 21 is 90% to 100%, for example, 90%, 93%, 95%, 97%, or 100%. The length direction of the collector line printing slots 21 is a third direction X2. Two collector line printing slots 21 are arranged in a third direction X2 to form a pair.

[0149] In at least one pair of current collector line printing slots 21, the two current collector line printing slots 21 are staggered in the third direction X2 and the fourth direction Y2, where the fourth direction Y2 intersects the third direction X2. In the third direction X2, the two current collector line printing slots 21 are respectively provided with a first overlapping printing slot 22 at their ends closest to each other. These two first overlapping printing slots 22 are at least partially arranged opposite each other in the fourth direction Y2, and the width of the widest part of at least one first overlapping printing slot 22 in the fourth direction Y2 is greater than the width of the current collector line printing slot 21.

[0150] The second printing screen 30 is provided with a plurality of busbar printing grooves 31. The length direction of the busbar printing grooves 31 is the fifth direction Y3. The busbar printing grooves 31 are provided with a plurality of second overlapping printing grooves 32 arranged at intervals along the fifth direction Y3. Each second overlapping printing groove 32 extends along the sixth direction X3 and protrudes from the busbar printing grooves 31. The sixth direction X3 intersects with the fifth direction Y3.

[0151] Optionally, the fourth direction Y2 is perpendicular to the third direction X2. Of course, the angle between the fourth direction Y2 and the third direction X2 can deviate slightly from 90°, for example, it can be 80°, 85°, 89°, 91° or 95°.

[0152] Optionally, the sixth direction X3 is perpendicular to the fifth direction Y3. Of course, the angle between the sixth direction X3 and the fifth direction Y3 can deviate slightly from 90°, for example, it can be 80°, 85°, 89°, 91° or 95°, and this embodiment does not limit this.

[0153] The printing process of this printing screen component is illustrated below:

[0154] First, the battery body is printed using a second printing screen 30; wherein, the busbar printing groove 31 is used to print the busbars, and the second overlap printing groove 32 is used to print the second overlap substructure. Then, the battery body is printed using a first printing screen 20; wherein, a pair of current collector printing grooves 21 are used to print a pair of current collectors, and the first overlap printing groove 22 is used to print the first overlap substructure, and each first overlap substructure is stacked on each second overlap substructure to form an overlap structure, thereby allowing two current collectors in a pair of current collectors to overlap on the same busbar through two overlap structures.

[0155] It should be noted that the first printing screen 20 and the second printing screen 30 do not necessarily have to be printed in the order described above.

[0156] The beneficial effects of this printing screen assembly are as follows:

[0157] The aperture ratio of the current collector line printing groove 21 in this printing screen assembly is 90% to 100%, which is higher than the maximum aperture ratio of 80% for wire mesh printing. It is understood that a higher aperture ratio indicates less obstruction within the opening, better paste flow, and the ability to print narrower current collector lines with fewer morphological defects. In this application, the aforementioned paste refers to the grid line printing paste for solar cells, such as silver paste or silver-aluminum paste.

[0158] In other words, the current collector grid printing groove 21 can print current collector grids with narrower line width and better morphology, thereby reducing costs by reducing the amount of paste used. Furthermore, the narrower line width results in a smaller shading area of ​​the current collector grid, which improves the conversion efficiency of the solar cell.

[0159] However, the longer the current collector grid printing groove 21 is, the lower the structural strength and the shorter the service life of the first printing screen 20. To shorten the length of the current collector grid printing groove 21, the current collector grid printing groove 21 in this embodiment is intermittently arranged. Specifically, two current collector grid printing grooves 21 are arranged in a third direction X2 to form a pair. In each pair of current collector grid printing grooves 21, the two current collector grid printing grooves 21 are staggered in the third direction X2 and the fourth direction Y2. Correspondingly, a pair of intermittently arranged current collector grid printing grooves 21 print a pair of intermittently arranged current collector grids. As analyzed in the first aspect, the current collection range of a pair of current collector grids is equivalent to the distance between the two ends of this pair of current collector grids in the second direction. In other words, in order to collect current from the surface of a battery body of a certain size, related technologies use a continuous, long current collector grid for current collection, while the solar cell of this application uses two intermittent, shorter current collector grids combined together for current collection. In other words, the current collector lines in this application are shorter, and correspondingly, the length of the current collector line printing groove 21 is also shorter, which makes the first printing screen 20 structurally stronger and has a longer service life. On the other hand, the shorter length of the current collector line printing groove 21 means that when the squeegee applies force on the first printing screen 20, the deformation of the current collector line printing groove 21 is smaller, thereby reducing printing offset and excessively thick grid lines caused by deformation of the current collector line printing groove 21.

[0160] To prevent grid breakage during welding at the overlap between the current collector and busbar lines, the printing screen assembly uses a second overlap printing groove 32 to print a second overlap substructure and a first overlap printing groove 22 to print a first overlap substructure. Each first overlap substructure is stacked on top of each second overlap substructure to form an overlap structure. Since the height of the first overlap substructure is equal to or slightly different from the height of the current collector line, the height at the overlap between the first and second overlap structures can be higher than the current collector line. In other words, the printing screen assembly achieves a wider and taller overlap structure than the current collector line through two printing operations. The welding performance of the overlap structure is positively correlated with its width and height. Higher width and height indicate a higher material content (e.g., silver), which helps the overlap structure resist the silver etching reaction of the solder strip during welding, preventing grid breakage.

[0161] In summary, this printing screen assembly, by optimizing the pattern of the collector grid printing groove 21, facilitates improved solar cell efficiency through the printing of narrower linewidth collector grids using the first printing screen 20. It also enhances the lifespan and printing quality of the first printing screen 20. Furthermore, the printing screen assembly prints a wider and higher overlap structure at the intersection of the collector grid lines and the busbar lines. This overlap structure is less prone to breakage during welding, reducing grid breakage and resulting in better current collection by the solar cell, thus improving its conversion efficiency.

[0162] The first printing screen is described in detail below.

[0163] In some embodiments, refer to Figures 7 to 9 The first printing screen 20 can be a steel plate screen, made of materials such as nickel steel, specifically a steel plate formed by one or more layers of nickel steel. The current collector line printing grooves 21 can be made on the first printing screen 20 by electroforming, laser drilling, etching, or other methods.

[0164] In some embodiments, such as Figure 8 As shown, each first overlapping printing groove 22 includes a first narrowing groove segment 221 and a first overlapping groove segment 222. On the third direction X2, the collector grid printing groove 21, the first narrowing groove segment 221 and the first overlapping groove segment 222 are connected end to end in sequence.

[0165] Specifically, the width of the first narrowing groove segment 221 in the fourth direction Y2 decreases in the direction away from the first overlapping groove segment 222, and the width of the widest part of the first narrowing groove segment 221 is greater than the width of the current collector line printing groove 21. The width of the first overlapping groove segment 222 in the fourth direction Y2 is greater than the width of the current collector line printing groove 21.

[0166] In this embodiment, the first overlap printing groove 22 is configured to print the first overlap substructure, the first overlap groove segment 222 is configured to print the first overlap segment, and the first narrowing groove segment 221 is configured to print the first narrowing segment. Therefore, according to the aforementioned width relationship, the width of the first overlap segment printed by the first printing screen 20, and the width of the widest part of the first narrowing segment, are greater than the width of the collector grid line, allowing the first overlap segment and the first narrowing segment to better block the silver etching reaction of the solder ribbon relative to the collector grid line. The width of the first narrowing groove segment 221 narrows in a direction away from the first overlap segment to reduce the wet weight of the paste during printing.

[0167] More in detail, such as Figure 8 As shown, the shape of the first overlapping groove segment 222 can be rectangular, and the shape of the first narrowing groove segment 221 can be trapezoidal, meaning that the narrowing of the first narrowing groove segment 221 is gradual. Of course, the narrowing of the first narrowing groove segment 221 can also be stepped. Furthermore, the width of the widest part of the first narrowing groove segment 221 can be equal to the width of the first overlapping groove segment 222, and the width of the narrowest part of the first narrowing groove segment 221 can be equal to the width of the collector wire printing groove 21.

[0168] Optionally, such as Figure 8 As shown, the first overlapping printing groove 22 further includes an extension groove segment 223, which is connected to the end of the first overlapping groove segment 222 away from the first narrowing groove segment 221. The dimension of the extension groove segment 223 in the fourth direction Y2 is the width of the extension groove segment 223. Specifically, the width of the extension groove segment 223 narrows in the direction away from the first overlapping groove segment 222; or, the width of the extension groove segment 223 is equal to the width of the first overlapping groove segment 222; or, the width of the extension groove segment 223 is equal to the width of the collector grid printing groove 21.

[0169] Specifically, the extension groove 223 is configured as a printing extension. Another function of the extension groove 223 is to extend the length of the first overlapping printing groove 22 so that the overlapping portion of the two first overlapping printing grooves 22 of a pair of collector grid printing grooves 21 is longer. It can be understood that one of the printing processes is to map the overlapping portion of the two first overlapping printing grooves 22 to the busbar. The longer the overlapping portion, the lower the requirement for printing accuracy.

[0170] Of course, the first overlapping printing groove 22 may not include the extension groove 223. In this case, the second overlapping printing groove 32 also includes the extension groove 223. The connection relationship between the extension groove 223 and other parts of the second overlapping printing groove 32 will be described in detail below when the second printing screen 30 is described in detail.

[0171] In some embodiments, such as Figure 7 and Figure 9As shown, multiple collector grid line printing slots 21 are arranged at intervals along the fourth direction Y2 to form a column, and multiple columns of collector grid line printing slots 21 are arranged along the third direction X2.

[0172] In two adjacent rows of collector grid line printing slots 21, one row of collector grid line printing slots 21 is a first side grid line printing slot 21a, and the other row of collector grid line printing slots 21 is a second side grid line printing slot 21b. In the fourth direction Y2, the first side grid line printing slots 21a and the second side grid line printing slots 21b are alternately arranged, and any first side grid line printing slot 21a and an adjacent second side grid line printing slot 21b form a pair of collector grid line printing slots 21.

[0173] In this embodiment, the first printing screen 20 prints multiple rows of current collector lines through the multi-row current collector line printing groove 21, so that the current collector lines are distributed on the surface of the battery body to better collect current.

[0174] Based on this, multiple current collector line printing slots 21 are equidistantly arranged within the same column of current collector line printing slots 21. In other words, the current collector line printing slots 21 are evenly distributed within the area where this column of current collector line printing slots 21 is located. This even distribution ensures that the amount of paste transferred on the screen is relatively consistent at each position, resulting in uniform coating thickness and weight of the paste on the solar cell semi-finished product. Furthermore, a column of evenly distributed current collector line printing slots 21 can print a column of evenly distributed current collector lines, making the photoelectric conversion performance of the solar cell in this area more similar, reducing performance differences, and thus improving the overall performance and stability of the solar cell.

[0175] Furthermore, in the fourth direction Y2, the spacing between each first side grid line printing groove 21a and the adjacent second side grid line printing groove 21b in two adjacent columns of current collector grid line printing grooves 21 is equal. In other words, in the area where these two columns of current collector grid line printing grooves 21 are set, the current collector grid line printing grooves 21 are evenly distributed. The even distribution of the current collector grid line printing grooves 21 ensures that the amount of paste transferred on the screen is relatively consistent at each position, resulting in uniform coating thickness and weight of the paste on the solar cell semi-finished product. Moreover, the two evenly distributed columns of current collector grid line printing grooves 21 can print two evenly distributed columns of current collector grid lines, making the photoelectric conversion performance of the solar cell in this area more similar, reducing performance differences, and thus improving the overall performance and stability of the solar cell.

[0176] The second printing screen is described in detail below.

[0177] like Figure 10 As shown, regarding the type of the second printing screen 30, the second printing screen 30 can be a wire mesh screen or the aforementioned high aperture ratio printing screen.

[0178] Reference Figure 10In some embodiments, each second overlapping printing groove 32 includes a second overlapping groove segment 321 and a second narrowing groove segment 322. The second overlapping groove segment 321 extends along the sixth direction X3, and one end of the second overlapping groove segment 321 in the sixth direction X3 intersects with the busbar. The second narrowing groove segment 322 is connected to the end of the second overlapping groove segment 321 away from the busbar and extends in the same direction as the second overlapping groove segment 321.

[0179] Specifically, the width of the second narrowing groove segment 322 in the fifth direction Y3 decreases in the direction away from the second overlapping groove segment 321. The width of the widest part of the second narrowing groove segment 322 is greater than the width of the collector grid printing groove 21; the width of the second overlapping groove segment 321 in the fifth direction Y3 is greater than the width of the collector grid printing groove 21.

[0180] In this embodiment, the second overlap printing groove 32 is configured to print the second overlap substructure, and the second overlap groove segment 321 is configured to print the second overlap segment. The second narrowing groove segment 322 is configured to print the second narrowing segment. Therefore, based on the aforementioned width relationship, the width of the second overlap segment printed by the second printing screen 30, and the width of the widest point of the second narrowing segment, are greater than the width of the collector grid line. This allows the second overlap segment and the second narrowing segment to better block the silver etching reaction of the solder ribbon relative to the collector grid line. The narrowing width of the second narrowing groove segment 322 further reduces the wet weight of the printing paste.

[0181] More specifically, the shape of the second overlapping groove 321 can be rectangular, and the shape of the second narrowing groove 322 can be trapezoidal, meaning that the narrowing of the second narrowing groove 322 is gradual. Of course, the narrowing of the second narrowing groove 322 can also be stepped. Furthermore, the width of the widest part of the second narrowing groove 322 can be the same as the width of the second overlapping groove 321, and the width of the narrowest part of the second narrowing groove 322 can be equal to the width of the collector wire printing groove 21.

[0182] Specifically, when the second overlapping printing groove 32 further includes an extension groove segment 223, the extension groove segment 223 is connected to the end of the second overlapping groove segment 321 away from the second narrowing groove segment 322. In the sixth direction X3, the extension groove segment 223 protrudes from the busbar on the side away from the second narrowing groove segment 322. The extension groove segment 223 is configured as a printing extension so that the overlapping structure can pass through the busbar.

[0183] Optionally, a plurality of second overlapping printing grooves 32 are alternately arranged on two opposite sides of the busbar printing groove 31 in the sixth direction X3, and each second overlapping printing groove 32 protrudes in a direction away from the busbar printing groove 31.

[0184] To print multiple spaced busbar lines, a plurality of busbar printing slots 31 are provided, spaced apart along the sixth direction X3. Optionally, the width of the busbar printing slots 31 is 15μm to 40μm to print busbar lines with a smaller light-shielding area and lower resistance.

[0185] Thirdly, embodiments of this application disclose a photovoltaic module, including a plurality of solar cells connected in series and / or in parallel, wherein at least one of the solar cells is the solar cell described in the first aspect, or at least one of the solar cells is a solar cell made of the screen printing plate assembly described in the second aspect.

[0186] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A solar cell, characterized in that, include: Battery body; A plurality of busbars, each of the busbars being disposed on the surface of the battery body, wherein the length direction of the busbars is a first direction; as well as Multiple current collector grid lines are disposed on the surface of the battery body and extend along a second direction, which intersects with the first direction; two current collector grid lines are arranged in the second direction to form a pair. In at least one pair of current collector grid lines, the two current collector grid lines are staggered in both the first direction and the second direction. In the second direction, the ends of the two current collector grid lines close to each other are respectively provided with overlapping structures. The two overlapping structures are staggered in the first direction and intersect with the same current collector grid line. The widest part of at least one overlapping structure is wider than the width of the current collector grid line in the first direction, and the highest point of this overlapping structure in the thickness direction of the battery body is also higher than the current collector grid line.

2. The solar cell according to claim 1, characterized in that, At least one of the overlapping structures on a pair of collector grid lines passes through the bus grid line along the second direction.

3. The solar cell according to claim 1, characterized in that, The overlapping structure includes a first overlapping substructure and a second overlapping substructure. The first overlapping substructure is integrally formed with the current collector grid line, and the second overlapping substructure is integrally formed with the current bus grid line. The first overlapping substructure is stacked on the side of the second overlapping substructure that is away from the battery body.

4. The solar cell according to claim 3, characterized in that, The length of the first overlapping substructure in the second direction is greater than the length of the second overlapping substructure in the second direction; And / or, the width of the widest part of the second overlapping substructure in the first direction is greater than the width of the widest part of the first overlapping substructure in the first direction.

5. The solar cell according to claim 3, characterized in that, The overlapping structure has an extension section, which is part of the first overlapping substructure; or, the extension section is part of the second overlapping structure. When the extension is part of the first overlap substructure, the first overlap substructure passes through the busbar along the second direction, the extension is the portion of the first overlap substructure that protrudes from the busbar, and the extension is located at the end of the first overlap substructure away from the connected collector grid. When the extension is part of the second overlap substructure, the second overlap substructure passes through the busbar along the second direction, the extension is the portion of the second overlap substructure that protrudes from the busbar, and the extension is located at one end of the second overlap substructure away from the connected collector busbar.

6. The solar cell according to claim 5, characterized in that, Each of the first overlapping substructures extends along the second direction and includes a first narrowing section and a first overlapping section that are connected end to end; The first overlap segment intersects with the busbar, and the width of the first overlap segment in the first direction is greater than the width of the collector busbar; The first narrowing segment is connected between the first overlapping segment and the collector grid line. The width of the first narrowing segment in the first direction narrows away from the first overlapping segment, and the width of the widest part of the first narrowing segment is greater than the width of the collector grid line. When the extension is part of the first overlap substructure, the extension is connected to the end of the first overlap away from the first narrowing section, and the extension protrudes from the busbar on the side away from the first narrowing section; the dimension of the extension in the first direction is the width of the extension, wherein the width of the extension narrows in the direction away from the first overlap; or, the width of the extension is equal to the width of the first overlap; or, the width of the extension is equal to the width of the collector wire.

7. The solar cell according to claim 6, characterized in that, Each of the second overlapping substructures extends along the second direction and includes a second overlapping section and a second narrowing section that are joined end to end; One end of the second overlapping section in the second direction intersects with the busbar, and the width of the second overlapping section in the first direction is greater than the width of the collector grid. The second narrowing segment is connected between the second overlapping segment and the collector grid line. The width of the second narrowing segment in the first direction narrows away from the second overlapping segment, and the width of the widest part of the second narrowing segment is greater than the width of the collector grid line. The first narrowing segment is stacked on the side of the second narrowing segment opposite to the battery body, and the first overlapping segment is stacked on the side of the second overlapping segment opposite to the battery body.

8. The solar cell according to claim 1, characterized in that, The height of the overlapping structure at its highest point in the thickness direction of the battery body is H1, and the height of the current collector grid line is H2, where H1 / H2≥1.1; The width of the widest part of the overlapping structure in the first direction is W1, and the width of the collector grid line is W2, where W1 / W2 = 1.01 to 10.

9. The solar cell according to claim 8, characterized in that, The height H1 of the highest point of the overlapping structure in the thickness direction of the battery body is 7μm to 10.5μm; the height H2 of the current collector grid line is 2μm to 8μm. And / or, the width W1 of the widest part of the overlapping structure in the first direction is 50μm to 100μm, and the width W2 of the collector grid line is 10μm to 20μm.

10. The solar cell according to claim 1, 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, with two adjacent columns of collector grid lines overlapping the same busbar. 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 lines and the second side grid lines are alternately arranged, and any first side grid line and an adjacent second side grid line form a pair of collector grid lines.

11. The solar cell according to claim 10, characterized in that, The multiple busbars are equidistantly arranged in the second direction; 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.

12. The solar cell according to any one of claims 1 to 11, characterized in that, The battery body includes a silicon substrate, a doped layer, and a first functional film. The doped layer and the first functional film are disposed on the front side of the silicon substrate in a direction away from the silicon substrate. Each of the current collector grid lines is disposed on the first functional film and passes through the first functional film to make ohmic contact with the doped layer. Each of the current bus grid lines is disposed on the side of the first functional film away from the silicon substrate. And / or, the first direction is perpendicular to the second direction.

13. A printing screen assembly for a solar cell as described in any one of claims 1 to 12, characterized in that, include: A first printing screen is provided with a plurality of current collector line printing grooves, wherein the opening ratio of the current collector line printing grooves is 90% to 100%. The length direction of the current collector wire printing groove is a third direction; two current collector wire printing grooves are arranged in the third direction to form a pair; in at least one pair of current collector wire printing grooves, the two current collector wire printing grooves are staggered in the third direction and the fourth direction, and in the direction where the fourth direction intersects the third direction, in the third direction, the two current collector wire printing grooves are respectively provided with a first overlapping printing groove at one end close to each other, the two first overlapping printing grooves are at least partially arranged opposite each other in the fourth direction, and the width of the widest part of at least one first overlapping printing groove in the fourth direction is greater than the width of the current collector wire printing groove; The second printing screen has a plurality of busbar printing grooves. The length direction of the busbar printing grooves is the fifth direction. The busbar printing grooves have a plurality of second overlapping printing grooves spaced apart along the fifth direction. Each second overlapping printing groove extends along the sixth direction and protrudes from the busbar printing groove. The sixth direction intersects with the fifth direction.

14. The printing screen assembly according to claim 13, characterized in that, Each of the first overlapping printing slots includes a first narrowing slot segment and a first overlapping slot segment; in the third direction, the current collector wire printing slot, the first narrowing slot segment and the first overlapping slot segment are connected end to end in sequence; Wherein, the width of the first narrowing groove segment in the fourth direction narrows away from the first overlapping groove segment, and the width of the widest part of the first narrowing groove segment is greater than the width of the current collector wire printing groove. The width of the first overlapping groove segment in the fourth direction is greater than the width of the current collector wire printing groove.

15. The printing screen assembly according to claim 14, characterized in that, The first overlapping printing groove further includes an extension groove segment connected to the end of the first overlapping groove segment away from the first narrowing groove segment; the dimension of the extension groove segment in the fourth direction is the width of the extension groove segment; wherein, the width of the extension groove segment narrows along the direction away from the first overlapping groove segment; or, the width of the extension groove segment is equal to the width of the first overlapping groove segment; or, the width of the extension groove segment is equal to the width of the current collector line printing groove.

16. The printing screen assembly according to claim 13, characterized in that, Each of the second overlapping printing grooves includes a second overlapping groove segment and a second narrowing groove segment. The second overlapping groove segment extends along the sixth direction, and one end of the second overlapping groove segment in the sixth direction intersects with the busbar. The second narrowing groove segment is connected to the end of the second overlapping groove segment away from the busbar and extends in the same direction as the second overlapping groove segment. Wherein, the width of the second narrowing groove segment in the fifth direction narrows away from the second overlapping groove segment, and the width of the widest part of the second narrowing groove segment is greater than the width of the current collector wire printing groove; the width of the second overlapping groove segment in the fifth direction is greater than the width of the current collector wire printing groove.

17. The printing screen assembly according to claim 13, characterized in that, Multiple current collector wire printing slots are arranged at intervals along the fourth direction to form a column, and multiple columns of current collector wire printing slots are arranged along the third direction. In two adjacent columns of the current collector grid lines, one column of the current collector grid lines is a first side grid line printing groove, and the other column of the current collector grid lines is a second side grid line printing groove. In the fourth direction, the first side grid line printing groove and the second side grid line printing groove are alternately arranged, and any first side grid line printing groove and an adjacent second side grid line printing groove form a pair of current collector grid lines printing grooves. The fourth direction is perpendicular to the third direction.

18. The printing screen assembly according to claim 17, characterized in that, In the same column of the current collector wire printing slots, multiple current collector wire printing slots are arranged at equal intervals; And / or, in the fourth direction, the spacing between each of the first side grid line printing slots in two adjacent columns of the current collector grid line printing slots and the adjacent second side grid line printing slots is equal.

19. The printing screen assembly according to any one of claims 13 to 18, characterized in that, Multiple second overlapping printing grooves are alternately arranged on two opposite sides of the busbar printing groove in the sixth direction, and each second overlapping printing groove protrudes in a direction away from the busbar printing groove; And / or, the number of the busbar printing slots is multiple, and the multiple busbar printing slots are spaced apart along the sixth direction; And / or, the sixth direction is perpendicular to the fifth direction.

20. 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 12, or at least one of the solar cells being a solar cell made of a screen printing assembly of any one of claims 13 to 19.

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