Solar cell and electrode structure thereof, printing screen assembly, photovoltaic assembly

Abstract

The application relates to the technical field of solar cells, in particular to a solar cell, an electrode structure of the solar cell, a printing screen assembly and a photovoltaic assembly. The electrode structure comprises a plurality of current collection grid lines, a busbar grid line and a lapping grid line. The extension direction of the current collection grid line is a first direction, and the plurality of current collection grid lines are arranged in a group in a second direction. In the first direction, the plurality of groups of current collection grid lines are arranged at intervals, so that each adjacent two groups of current collection grid lines have a broken part. The busbar grid line is arranged at the broken part. At least one group of current collection grid lines is electrically connected to the busbar grid line through the lapping grid line; each lapping grid line comprises a connecting sub-grid line and M lapping sub-grid lines, in each lapping grid line, the connecting sub-grid line intersects N current collection grid lines in the same group, and the M lapping sub-grid lines are connected between the connecting sub-grid line and the busbar grid line, N is a positive integer greater than M, so that the number of lapping sub-grid lines required when the current collection grid line lapping the busbar grid line is reduced.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a solar cell and its electrode structure, a printing screen assembly, and a photovoltaic module. Background Technology

[0002] One direction for reducing costs and increasing efficiency in solar cells is to optimize the electrode structure pattern. Current collector grid patterns tend to reduce the structural strength and shorten the lifespan of printing screens, hindering the printing of narrower linewidth collector grids for cost reduction and efficiency improvement. Even after optimizing the collector grid pattern to solve these problems, the shading area of ​​other grid lines in the electrode structure remains relatively large, further affecting the improvement of solar cell conversion efficiency. Utility Model Content

[0003] This application discloses a solar cell and its electrode structure, printing screen assembly, and photovoltaic module, which can reduce the number of overlapping sub-grids required when the current collector grid lines overlap with the busbar grid lines. Reducing the number of overlapping sub-grid lines helps to reduce the overall shading area of ​​the electrode structure and the wet weight of the paste during printing, thereby helping to reduce the cost and increase the efficiency of the solar cell.

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

[0005] Multiple collector grid lines are provided, with the extension direction of the collector grid lines being a first direction. The multiple collector grid lines are arranged in a group at intervals along a second direction, and the first direction intersects the second direction. In the first direction, the multiple groups of collector grid lines are arranged at intervals, such that there is a break between each two adjacent groups of collector grid lines.

[0006] A busbar, at least a portion of which is disposed at the break portion, and which extends along the second direction; and

[0007] The overlapping gate wires, at least one group of the collector gate wires, are electrically connected to the bus gate wires through the overlapping gate wires; each overlapping gate wire includes a connecting sub-gate wire and M overlapping sub-gate wires, in each overlapping gate wire, the connecting sub-gate wire intersects with N collector gate wires in the same group, and the M overlapping sub-gate wires are connected between the connecting sub-gate wire and the bus gate wire, so that the N collector gate wires in the same group are electrically connected to the bus gate wire through the M overlapping sub-gate wires; wherein, M is a positive integer, and N is a positive integer greater than M.

[0008] In a possible implementation of the first aspect, two adjacent sets of collector grids in the first direction are electrically connected to the same bus grid through the overlapping grid.

[0009] In a possible implementation of the first aspect, the overlapping grid line includes a first type of overlapping grid line, and the number of connecting sub-grid lines in each first type of overlapping grid line is two;

[0010] In each of the first type of overlapping grid lines, two connecting sub-grid lines are spaced apart along the first direction, and the two connecting sub-grid lines are located on different sides of the same bus grid line. M overlapping sub-grid lines are connected between the two connecting sub-grid lines, and each overlapping sub-grid line also passes through the bus grid line along the first direction. Each of the two connecting sub-grid lines intersects with two sets of collector grid lines adjacent to each other in the first direction, so that the two sets of collector grid lines are electrically connected to the same bus grid line through a first type of overlapping grid line.

[0011] In a possible implementation of the first aspect, the orthographic projections of two connecting sub-grids in each of the first type of overlapping grids in the first direction coincide, and the orthographic projections of two sets of collector grids connected to the same first type of overlapping grid coincide in the first direction.

[0012] In a possible implementation of the first aspect, the overlapping grid line includes a second type of overlapping grid line, wherein the number of the connecting sub-grid lines in the second type of overlapping grid line is one, the connecting sub-grid line and the bus grid line are spaced apart in the first direction, and M overlapping sub-grid lines are connected between the connecting sub-grid line and the bus grid line; the connecting sub-grid line also intersects with a group of collector grid lines, such that the group of collector grid lines are electrically connected to the bus grid line through a second type of overlapping grid line.

[0013] In a possible implementation of the first aspect, the busbar is connected to a plurality of overlapping busbars of the second type spaced apart along the second direction;

[0014] On the same busbar, the connecting sub-charts of two adjacent second-type overlapping charts are located on different sides of the busbar, and the orthographic projections of these two connecting sub-charts in the first direction are staggered.

[0015] In the possible implementations of the first aspect, M is 1 and N is 2;

[0016] In each group of collector grid lines, two collector grid lines are electrically connected to the bus grid line through a lap sub-grid line, and this lap sub-grid line is located between the two collector grid lines in the first direction.

[0017] In a possible implementation of the first aspect, at least three sets of the collector grid lines are spaced apart along the first direction and have at least two breaks, the bus grid lines are at least two, each of the bus grid lines is respectively disposed at each of the breaks, and at least one set of the collector grid lines is located between the two bus grid lines;

[0018] In the first direction, the two ends of each set of collector grids located between the two bus grids are electrically connected between the two bus grids via the overlapping grids.

[0019] In a possible implementation of the first aspect, multiple sets of the collector grid lines are arranged in a column along the second direction, and the multiple columns of the collector grid lines are spaced apart along the first direction. A bus grid line is provided between each pair of adjacent columns of the collector grid lines, and multiple overlapping grid lines spaced apart along the second direction are connected to each bus grid line. Each set of the collector grid lines in two adjacent columns of the collector grid lines is electrically connected to the same bus grid line through the overlapping grid lines.

[0020] In a possible implementation of the first aspect, the connecting sub-gate line extends along the second direction;

[0021] And / or, the connecting sub-gate lines pass through the intersecting collector gate lines along the second direction;

[0022] And / or, the connecting sub-grid line is connected to one end of the collector grid line near the bus grid line;

[0023] And / or, the overlapping subgrid line extends along the first direction;

[0024] And / or, the overlapping sub-grid line passes through the intersecting connecting sub-grid lines along the first direction;

[0025] And / or, the overlapping sub-grid line passes through the intersecting busbar lines along the first direction;

[0026] And / or, the width of the widest point of the overlapping sub-grid line in the second direction is greater than the width of the connecting sub-grid line in the first direction;

[0027] And / or, the width of the overlapping sub-grid line in the second direction narrows away from the intersecting busbar lines;

[0028] And / or, the first direction is perpendicular to the second direction;

[0029] And / or, the width of the collector grid line is 5μm to 20μm.

[0030] Secondly, embodiments of this application disclose a solar cell, comprising:

[0031] Battery body; and

[0032] The electrode structure as described in the first aspect is disposed on the surface of the battery body.

[0033] In a possible implementation of the second 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 sequentially stacked on the surface of the silicon substrate in a direction away from the silicon substrate. The busbar and the connecting sub-gate are disposed on the side of the first functional film away from the doped layer. The current collector and the connecting sub-gate pass through the first functional film and make ohmic contact with the doped layer.

[0034] Thirdly, embodiments of this application disclose a printing screen assembly, including:

[0035] A first printing screen is provided with a busbar printing groove and a connecting printing groove. The busbar printing groove extends in a third direction. The connecting printing groove is spaced apart from the busbar printing groove in a fourth direction with a spacing of D1. The fourth direction intersects the third direction. The length of the connecting printing groove in the third direction is L1.

[0036] A second printing screen is provided with collector grid printing slots with an opening ratio of 90% to 100%. The collector grid printing slots extend along a fifth direction. N collector grid printing slots are spaced apart in a group along a sixth direction, which intersects the fifth direction. The dimension of each group of collector grid printing slots in the sixth direction is D2, where D2 ≤ L1. Multiple groups of collector grid printing slots are spaced apart along the fifth direction. In the fifth direction, there is a discontinuity region between each two adjacent groups of collector grid printing slots. The width of the discontinuity region in the fifth direction is W, where W / 2 ≤ D1. At least one group of collector grid printing slots extends M overlapping printing slots into the spacing region. Where M is a positive integer and N is a positive integer greater than M.

[0037] In a possible implementation of the third aspect, there are multiple connecting printing slots, and every two connecting printing slots spaced apart in the fourth direction constitute a pair; in a pair of connecting printing slots, the orthographic projections of the two connecting printing slots in the fourth direction coincide, and the two connecting printing slots are located on different sides of the same busbar printing slot.

[0038] At least one set of the current collector wire printing grooves extends M of the overlapping printing grooves through the interval area along the fifth direction and into the setting area of ​​the adjacent set of the current collector wire printing grooves.

[0039] In a possible implementation of the third aspect, there are multiple connecting printing slots, which are arranged in a row along the third direction. In the row of connecting printing slots, each pair of adjacent connecting printing slots is located on different sides of the same busbar printing slot, and each pair of adjacent connecting printing slots is staggered along the third direction.

[0040] In the fifth direction, the overlapping printing grooves extend from the respective areas of the two adjacent sets of the current collector wire printing grooves.

[0041] In the possible implementations of the third aspect, M is 1 and N is 2;

[0042] In each group of the current collector wire printing slots, one of the overlapping printing slots is located between two of the current collector wire printing slots in the sixth direction.

[0043] In a possible implementation of the third aspect, the number of the busbar printing slots is multiple, and the multiple busbar printing slots are spaced apart along the fourth direction;

[0044] Multiple sets of the current collector wire printing grooves are arranged in a column along the sixth direction, and multiple columns of the current collector wire printing grooves are spaced apart along the fifth direction. There is a discontinuity area between each pair of adjacent columns of the current collector wire printing grooves.

[0045] Wherein, the spacing between two adjacent busbar printing slots in the fourth direction is D3, and the length of each column of busbar printing slots in the fifth direction is L2; ​​wherein, D3 > L2.

[0046] In a possible implementation of the third aspect, the connecting printing groove extends along the third direction;

[0047] And / or, the third direction is perpendicular to the fourth direction;

[0048] And / or, the overlapping printing groove extends along the fifth direction;

[0049] And / or, the fifth direction is perpendicular to the sixth direction;

[0050] And / or, the width of the overlapping printing groove in the sixth direction is greater than the width of the connecting printing groove in the fourth direction.

[0051] Fourthly, embodiments of this application disclose a photovoltaic module comprising a plurality of electrically connected solar cells; at least one of the solar cells having an electrode structure as described in the first aspect; or, at least one of the solar cells being a solar cell as described in the second aspect; or, the electrode structure of at least one of the solar cells being printed using a screen printing assembly as described in the third aspect.

[0052] Compared with the prior art, the beneficial effects of this application include at least the following:

[0053] The current collector grids of this electrode structure are intermittently arranged, with multiple sets of current collector grids spaced apart, and each pair of adjacent sets of current collector grids has a break. In other words, in order to collect current over a certain area, related technologies use continuous, long current collector grids, while the solar cell of this application uses multiple sets of intermittent, shorter current collector grids combined together for current collection.

[0054] Correspondingly, the printing slots for the current collector lines on the printing screen are also intermittently arranged, and the length of each individual current collector line printing slot is relatively short. Since the current collector line printing slots are the weakest areas on a high-aperture printing screen, the structural strength of the high-aperture printing screen is negatively correlated with the length of the current collector line printing slots. In other words, the shorter the length of the current collector line printing slots, the shorter the weak area on the high-aperture printing screen, and the stronger the structural strength of the high-aperture printing screen, resulting in a longer service life. Furthermore, the shorter the current collector line printing slots, the less deformation they undergo during printing, thus reducing printing misalignment and excessively thick grid lines caused by current collector line deformation.

[0055] Because high aperture ratio printing screens have good paste throughput when printing current collector lines, the electrode structure of this application can reduce costs and increase efficiency by printing narrower linewidth current collector lines using high aperture ratio printing screens. At the same time, high aperture ratio printing screens also have high structural strength and long service life.

[0056] Based on this, N collector grid lines in the same group are electrically connected to the bus grid lines through M overlapping sub-grid lines, where M is a positive integer and N is a positive integer greater than M. This means that the number of overlapping sub-grid lines required to connect a group of collector grid lines to the bus grid lines is less than the number of collector grid lines, resulting in a smaller required number of overlapping sub-grid lines. The overlapping sub-grid lines are wider grid lines to meet the requirements for preventing solder breakage, and their light-shielding area is larger. In other words, reducing the number of overlapping sub-grid lines helps reduce the overall light-shielding area of ​​the electrode structure and the wet weight of the printing paste, thus contributing to cost reduction and efficiency improvement of solar cells.

[0057] In summary, the electrode structure of this application, by setting intermittent current collector lines, facilitates cost reduction and efficiency improvement through printing narrower linewidth current collector lines using a high aperture ratio printing screen. Simultaneously, the high aperture ratio printing screen also possesses higher structural strength and a longer service life. Furthermore, this electrode structure reduces the number of overlapping sub-grid lines required when the current collector lines overlap with the busbars. This reduction in the number of overlapping sub-grid lines helps to decrease the overall light-shielding area of ​​the electrode structure and the wet weight of the printing paste, thereby contributing to cost reduction and efficiency improvement in solar cells. 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 an electrode structure;

[0060] Figure 2 This is a schematic diagram of an electrode structure (the overlapping grid line is a first type of overlapping grid line) disclosed in an embodiment of this application;

[0061] Figure 3 for Figure 2 A magnified view of a portion of region I shown in the diagram;

[0062] Figure 4 This is a schematic diagram of an electrode structure (the overlapping grid line is a second type of overlapping grid line) disclosed in an embodiment of this application;

[0063] Figure 5 for Figure 4 A magnified view of a portion of region II shown in the diagram;

[0064] Figure 6 This is a cross-sectional view of the solar cell disclosed in the embodiments of this application at the location where the collector grid lines are installed;

[0065] Figure 7 This is a cross-sectional view of the solar cell disclosed in the embodiments of this application at the location where the busbar is installed;

[0066] Figure 8 This is a cross-sectional view of the solar cell disclosed in an embodiment of this application at the location where the connecting sub-grid lines are set;

[0067] Figure 9 This is a cross-sectional view of the solar cell disclosed in the embodiments of this application at the location where the overlapping sub-grid lines are set;

[0068] Figure 10This is a schematic diagram of the structure of the first printing screen disclosed in the embodiments of this application;

[0069] Figure 11 for Figure 10 A magnified view of a portion of region III shown in the diagram;

[0070] Figure 12 Is with Figure 10 A schematic diagram of the structure of the second printing screen that matches the first printing screen.

[0071] Figure 13 for Figure 12 A magnified view of region IV shown in the diagram;

[0072] Figure 14 This is another structural schematic diagram of the first printing screen disclosed in the embodiments of this application;

[0073] Figure 15 Is with Figure 14 A schematic diagram of the structure of the second printing screen that matches the first printing screen.

[0074] Figure 16 This is a schematic diagram of the structure of the photovoltaic module disclosed in the embodiments of this application.

[0075] Explanation of reference numerals in the attached figures:

[0076] 10. Solar cell; 11. Electrode structure; 111. Current collector grid line; 112. Busbar grid line; 113. Overlapping grid line; 1131. Connecting sub-grid line; 1132. Overlapping sub-grid line; 114. Break-off section; X1. First direction; Y1. Second direction; 12. Cell body; 121. Silicon substrate; 122. Doped layer; 123. First functional film; 124. Dielectric layer; 125. Doped polycrystalline silicon layer; 126. Second functional film;

[0077] 20. First printing screen; 21. Busbar printing groove; 22. Connecting printing groove; X2, Fourth direction; Y2, Third direction;

[0078] 30. Second printing screen; 31. Collector grid printing groove; 32. Intermittent area; 33. Overlapping printing groove; X3. Fifth direction; Y3. Sixth direction;

[0079] 40. Electrical connectors. Detailed Implementation

[0080] 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.

[0081] In this application, the terms "set up," "equipped with," and "connected" 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.

[0082] 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.

[0083] One way to reduce costs and increase efficiency in 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. The reduced shading area allows the solar cell to absorb more light, thus improving its conversion efficiency. Lowering the wet weight of the printing paste helps reduce the amount of paste used, thereby reducing the production cost of the solar cell.

[0084] Narrow-line-width subgrids 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 holes of the wire mesh, limiting the opening rate to only about 80%. The presence of these steel wires affects the transmission of the printing ink. When wire mesh is used to print narrow subgrids, poor ink transmission leads to printing abnormalities and poor subgrid morphology. In other words, wire mesh printing is not suitable for printing narrow-line-width subgrids, which hinders the improvement of conversion efficiency in solar cells by narrowing the subgrid linewidth.

[0085] High aperture ratio printing screens are more suitable for printing narrower subgrids, such as fully open steel screens. This is because when creating the printing holes with such screens, almost no material remains in the opening area, whereas steel wire screens only remove some material when creating the slots, but retain the steel wire in the opening area. In other words, the aperture ratio of a high aperture ratio printing screen is higher than that of a steel wire screen, reaching 90% to 100% (including endpoint values), which can be measured by a screen inspection instrument. The printing holes on a high aperture ratio printing screen have very little or no obstruction. The ink experiences less resistance when passing through the printing holes, resulting in better ink permeability.

[0086] However, current collector grid patterns tend to reduce the structural strength and shorten the lifespan of high aperture ratio printing screens, hindering cost reduction and efficiency improvement when printing narrower linewidth collector grids. This is because current collector grid patterns consist of a long, continuous grid line, with its length only slightly less than the size of the silicon substrate. Correspondingly, on high aperture ratio printing screens, the length of the printing grooves for the collector grid is only slightly less than the size of the high aperture ratio printing screen. However, high aperture ratio printing screens lack internal structures such as steel wires for stretching and structural reinforcement. It is understandable that when the printing grooves are too long, the structural strength of the high aperture ratio printing screen is easily affected, thus impacting its lifespan. Furthermore, when the squeegee applies force to the high aperture ratio printing screen, excessively long printing grooves are prone to deformation, leading to changes in printing position and increased opening, resulting in printing deviations and coarse grids. These printing abnormalities increase and worsen with increasing printing groove length.

[0087] The inventor's research revealed that, see [link / reference] Figure 1 The current collector lines 111 in the electrode structure 11 can be designed as discontinuous current collector lines 111 to shorten their length. Specifically, the solar cell 10 achieves a similar current collection effect to longer current collector lines by combining multiple discontinuous, shorter current collector lines 111. The discontinuous current collector lines 111 are shorter in length. Since the length of the current collector line printing groove is the same as the length of the current collector line 111, in other words, the length of the current collector line printing groove is also shorter. Based on the above analysis, a shorter current collector line printing groove is beneficial for improving the structural strength of the printing screen and reducing printing defects.

[0088] Considering that the collector grid line 111 is designed as an intermittent collector grid line 111, a break 114 is formed between two adjacent collector grid lines 111. A connecting structure needs to be provided at the break 114 to connect the two intermittent collector grid lines 111 into a continuous state. For example, an overlapping grid line 113 can be provided between the break 114. The overlapping grid line 113 connects the two collector grid lines 111 and intersects with the bus grid line 112. This not only allows the two broken collector grid lines 111 to be reconnected into a continuous state, but also allows the two collector grid lines 111 to converge to the bus grid line 112 through the overlapping grid line 113.

[0089] However, each collector grid line 111 requires a lap grid line 113 to overlap the busbar line 112, resulting in a large number of lap grid lines 113. Since the lap grid lines 113 need to overlap with the solder ribbon at the module end, their width must be large to prevent them from being broken by the solder ribbon. This ensures sufficient electrode material to block the silver etching reaction of the solder ribbon, but it also leads to a larger shading area and a larger wet weight of the printing paste. In other words, even after optimizing the pattern of the collector grid lines 111, allowing the electrode structure 11 to print narrower linewidth collector grid lines 111 and reduce the shading area, the larger number of lap grid lines 113 still increases the shading area of ​​the electrode structure 11, thus affecting the further improvement of the solar cell 10's conversion efficiency.

[0090] Based on the above analysis, this application provides an electrode structure for a solar cell. This electrode structure, by setting intermittent current collector lines, facilitates cost reduction and efficiency improvement through printing narrower linewidth current collector lines using a high aperture ratio printing screen. Simultaneously, the high aperture ratio printing screen also possesses higher structural strength and a longer service life. Furthermore, this electrode structure reduces the number of overlapping sub-grid lines required when the current collector lines overlap with the busbars. Reducing the number of overlapping sub-grid lines helps decrease the overall light-shielding area of ​​the electrode structure and the wet weight of the printing paste, thereby contributing to cost reduction and efficiency improvement in the solar cell.

[0091] It should be noted that, in this application, "paste" refers to the paste used for printing electrode structures. Examples include silver paste, silver-aluminum paste, or silver-coated copper paste.

[0092] The technical solution of this utility model will be described below with reference to the embodiments and accompanying drawings.

[0093] Firstly, see [the following] Figure 2 and Figure 3 This application discloses an electrode structure 11 of a solar cell 10, including multiple current collector grid lines 111, current collector grid lines 112, and overlapping grid lines 113.

[0094] The extension direction of the collector grid line 111 is the first direction X1, and multiple collector grid lines 111 are arranged in a group at intervals along the second direction Y1, with the first direction X1 intersecting the second direction Y1. In the first direction X1, multiple groups of collector grid lines 111 are arranged at intervals, so that there is a break portion 114 between each two adjacent groups of collector grid lines 111.

[0095] At least a portion of the busbar 112 is disposed at the break portion 114, and the busbar 112 extends along the second direction Y1.

[0096] At least one group of collector grid lines 111 are electrically connected to bus grid lines 112 via overlapping grid lines 113. Each overlapping grid line 113 includes a connecting sub-grid line 1131 and M overlapping sub-grid lines 1132. In each overlapping grid line 113, the connecting sub-grid line 1131 intersects with N collector grid lines 111 in the same group, and the M overlapping sub-grid lines 1132 connect the connecting sub-grid line 1131 and the bus grid line 112, so that the N collector grid lines 111 in the same group are electrically connected to the bus grid line 112 via the M overlapping sub-grid lines 1132. Wherein, M is a positive integer, and N is a positive integer greater than M.

[0097] The beneficial effects of the electrode structure 11 will be described in detail below.

[0098] The current collector grid lines 111 of the electrode structure 11 are intermittently arranged, with multiple sets of current collector grid lines 111 spaced apart, and each pair of adjacent sets of current collector grid lines 111 having a break 114. In other words, in order to collect current over a certain area, related technologies use continuous, long current collector grid lines 111 for current collection, while the solar cell 10 of this application uses multiple sets of intermittent, shorter current collector grid lines 111 combined together for current collection.

[0099] Correspondingly, the printing grooves for the current collector lines 111 on the printing screen are also intermittently arranged, and the length of each individual current collector line 111 printing groove is relatively short. Since the current collector line 111 printing groove is a weak area on the high aperture ratio printing screen, the structural strength of the high aperture ratio printing screen is negatively correlated with the length of the current collector line 111 printing groove. In other words, the shorter the length of the current collector line 111 printing groove, the shorter the weak area on the high aperture ratio printing screen, and the stronger the structural strength of the high aperture ratio printing screen, resulting in a longer service life. Furthermore, the shorter the current collector line 111 printing groove, the less deformation it undergoes during printing, thereby reducing printing offset and excessively thick grid lines caused by deformation of the current collector line 111 printing groove.

[0100] Because high-aperture printing screens offer better ink flow during printing of the current collector lines 111, this application can print narrower linewidth current collector lines 111 using high-aperture printing screens. Furthermore, high-aperture printing screens also possess higher structural strength and a longer service life. Research indicates that the linewidth of the current collector lines 111 in this application can be narrowed to 5μm–20μm, resulting in a reduction in the light-shielding area of ​​the current collector lines 111 and a decrease in the wet weight of the ink during printing, thus contributing to cost reduction and efficiency improvement of the solar cell 10.

[0101] Based on this, the N collector grid lines 111 in the same group are electrically connected to the bus grid line 112 through M overlapping sub-grid lines 1132, where M is a positive integer and N is a positive integer greater than M. That is, the number of overlapping sub-grid lines 1132 required for a group of collector grid lines 111 to overlap the bus grid line 112 is less than the number of collector grid lines 111, thus requiring fewer overlapping sub-grid lines 1132. The overlapping sub-grid lines 1132 are wider grid lines to meet the requirements for preventing solder breakage, and their light-shielding area is larger. In other words, reducing the number of overlapping sub-grid lines 1132 helps reduce the overall light-shielding area of ​​the electrode structure 11 and the wet weight of the paste during printing, thereby contributing to cost reduction and efficiency improvement of the solar cell 10.

[0102] In summary, the electrode structure 11 of this application, by setting intermittent current collector lines 111, facilitates cost reduction and efficiency improvement by printing narrower linewidth current collector lines 111 using a high aperture ratio printing screen. Simultaneously, the high aperture ratio printing screen also possesses higher structural strength and a longer service life. Furthermore, the electrode structure 11 reduces the number of overlapping sub-grid lines 1132 required when the current collector lines 111 overlap with the busbar lines 112. This reduction in the number of overlapping sub-grid lines 1132 helps reduce the overall light-shielding area of ​​the electrode structure 11 and the wet weight of the printing paste, thereby contributing to cost reduction and efficiency improvement of the solar cell 10.

[0103] Optionally, M is 1 and N is 2. See also Figure 2 and Figure 3 In other words, in each group of collector grid lines 111, two collector grid lines 111 are electrically connected to the bus grid line 112 through a connecting sub-grid line 1132, and this connecting sub-grid line 1132 is located between the two collector grid lines 111 in the first direction X1. In this way, the current of the two collector grid lines 111 is connected to the bus grid line 112 through the connecting sub-grid line 1132, requiring fewer connecting sub-grid lines 1132 than the number of collector grid lines 111, thus reducing the number of connecting sub-grid lines 1132 and lowering the overall light-shielding area of ​​the electrode structure 11. Furthermore, when the connecting sub-grid line 1132 conducts the current of the two collector grid lines 111, the current intensity is relatively low, since the transmission loss of the connecting sub-grid line 1132 is proportional to the current intensity. When the current intensity is low, the transmission loss of the connecting sub-grid line 1132 is low.

[0104] Of course, M and N can also be other values, and this application does not limit them. For example, M is 1 and N is 3; or M is 2 and N is 3; or M is 1 and N is 4.

[0105] In some embodiments, see Figure 2 and Figure 3 In the first direction X1, two adjacent sets of collector grid lines 111 are electrically connected to the same bus grid line 112 through overlapping grid lines 113. In other words, the current of two adjacent sets of collector grid lines 111 in the first direction X1 is collected to the same bus grid line 112 through overlapping grid lines 113. These two sets of collector grid lines 111 share a single bus grid line 112 for current collection, thereby improving the utilization rate of the bus grid line 112 and reducing the number of bus grid lines 112 required.

[0106] In this application, there are several ways to achieve the electrical connection of two adjacent sets of collector grid lines 111 to the same bus grid line 112 through overlapping grid lines 113, as follows:

[0107] In one possible implementation, such as Figure 2 and Figure 3 As shown, the overlap grid line 113 includes a first type of overlap grid line 113, and each first type of overlap grid line 113 has two connecting sub-grid lines 1131. In each first type of overlap grid line 113, the two connecting sub-grid lines 1131 are spaced apart along a first direction X1, and the two connecting sub-grid lines 1131 are located on different sides of the same bus grid line 112. M overlap sub-grid lines 1132 are connected between the two connecting sub-grid lines 1131, and each overlap sub-grid line 1132 also passes through the bus grid line 112 along the first direction X1. Each of the two connecting sub-grid lines 1131 intersects with two sets of collector grid lines 111 adjacent to each other in the first direction X1, so that the two sets of collector grid lines 111 are electrically connected to the same bus grid line 112 through a first type of overlap grid line 113.

[0108] In this implementation, the two sets of collector grid lines 111 share a single overlapping sub-grid line 1132 in a first-type overlapping grid line 113, further reducing the number of overlapping sub-grid lines 1132 required and thus reducing the light-shielding area of ​​the first-type overlapping grid line 113. Furthermore, this design provides leeway for the printing alignment of the overlapping sub-grid line 1132 and the bus grid line 112. This is because the overlapping sub-grid line 1132 in the first-type overlapping grid line 113 also passes through the bus grid line 112 along the first direction X1; that is, both ends of the overlapping sub-grid line 1132 protrude from the bus grid line 112 in the first direction X1. When the overlapping sub-grid line 1132 and the bus grid line 112 are printed off in the first direction X1 and the offset is within a reasonable range, the overlapping sub-grid line 1132 can still overlap the bus grid line 112.

[0109] It should be noted that, since the lap sub-grid 1132 in the first type of lap grid 113 passes through the bus grid 112 along the first direction X1, the lap sub-grid 1132 is separated into two connected lap segments by the bus grid 112, and each set of collector grids 111 transmits current through each lap segment. That is to say, although the lap sub-grid 1132 needs to transmit the current of two sets of collector grids 111, the current of these two sets of collector grids 111 is diverted to the two lap segments of the same lap sub-grid 1132, the current intensity in the lap sub-grid 1132 is still low, and the transmission loss of the lap sub-grid 1132 is still low.

[0110] Furthermore, the orthographic projections of the two connecting sub-grid lines 1131 in each of the first type of overlapping grid lines 113 coincide in the first direction X1, and the orthographic projections of the two sets of collector grid lines 111 connected to the same first type of overlapping grid line 113 also coincide in the first direction X1. It is understood that the relatively symmetrical pattern of the first type of overlapping grid lines 113 is beneficial to improving the aesthetic appearance of the electrode structure 11. Moreover, the two sets of collector grid lines 111 connected to the first type of overlapping grid line 113 are also symmetrically arranged, which is beneficial to the uniform distribution of the collector grid lines 111. The uniformly distributed collector grid lines 111 can more efficiently collect the current from the surface of the solar cell 10, and also make the current density distribution on the surface of the solar cell 10 more uniform.

[0111] In another possible implementation, such as Figure 4 and Figure 5 As shown, the overlap grid line 113 includes a second type of overlap grid line 113. The second type of overlap grid line 113 contains one connecting sub-grid line 1131. This connecting sub-grid line 1131 is spaced apart from the bus grid line 112 in the first direction X1, and M overlap sub-grid lines 1132 are connected between this connecting sub-grid line 1131 and the bus grid line 112. This connecting sub-grid line 1131 also intersects with a set of collector grid lines 111, so that this set of collector grid lines 111 is electrically connected to the bus grid line 112 through a second type of overlap grid line 113.

[0112] In this implementation, each group of collector grid lines 111 is electrically connected to the bus grid line 112 through each of the second type of overlapping grid lines 113. Compared with the first type of overlapping grid lines 113, although there is only one group of collector grid lines 111 connected by the second type of overlapping grid lines 113, there is only one connecting sub-grid line 1131 of the second type of overlapping grid lines 113, and the overlapping sub-grid line 1132 only needs to be connected between this connecting sub-grid line 1131 and the bus grid line 112. Its length is relatively shorter, which is beneficial to reducing its light-blocking area.

[0113] Optionally, a plurality of second-type overlapping grid lines 113 spaced apart along the second direction Y1 are connected to the busbar 112. On the same busbar 112, the connecting sub-grid lines 1131 of two adjacent second-type overlapping grid lines 113 are located on different sides of the busbar 112, and the orthographic projections of these two connecting sub-grid lines 1131 in the first direction X1 are staggered. It can be understood that the orthographic projections of the two sets of collector grid lines 111 intersecting with these two connecting sub-grid lines 1131 in the first direction X1 can also be staggered. In this way, these two sets of staggered collector grid lines 111 can each overlap the same busbar 112 through a second-type overlapping grid line 113.

[0114] It should be noted that the type of overlapping grid lines 113 in the electrode structure 11 of this application can be one or more. For example, such as Figure 3 As shown, all the overlapping grid lines 113 in the electrode structure 11 can be of the first type; or, as Figure 5 As shown, all the overlapping grid lines 113 in the electrode structure 11 can be of the second type; or, in the electrode structure, a portion of the overlapping grid lines are of the first type, and the rest are of the second type.

[0115] In some embodiments, please refer to Figure 3 and Figure 5 At least three sets of collector grid lines 111 are spaced apart along a first direction X1 and have at least two break portions 114. There are at least two bus grid lines 112, each disposed at a break portion 114. At least one set of collector grid lines 111 is located between two bus grid lines 112. Along the first direction X1, the two ends of each set of collector grid lines 111 located between two bus grid lines 112 are electrically connected to the two bus grid lines 112 via overlapping grid lines 113. That is, both ends of each set of collector grid lines 111 located between two bus grid lines 112 can transmit current to the bus grid line 112, thereby shortening the current transmission path of the collector grid lines 111. Even if a printed grid break occurs in the middle of the collector grid line 111, the two broken sections of the collector grid line 111 can still be connected to the bus grid line 112 to transmit current, thereby improving the current collection efficiency of the collector grid line 111 and improving the conversion efficiency of the solar cell 10.

[0116] Based on this, multiple sets of collector grid lines 111 are arranged in a column along the second direction Y1, and the multiple columns of collector grid lines 111 are spaced apart along the first direction X1. A bus grid line 112 is provided between each pair of adjacent columns of collector grid lines 111, and multiple overlapping grid lines 113 spaced apart along the second direction Y1 are connected to each bus grid line 112. Each set of collector grid lines 111 in two adjacent columns of collector grid lines 111 is electrically connected to the same bus grid line 112 through the overlapping grid lines 113. In this way, the number of overlapping sub-grid lines 1132 required for each column of collector grid lines 111 to overlap with the bus grid line 112 will be greatly reduced, further reducing the light-shielding area and printing paste consumption of the electrode structure 11, which is beneficial to the cost reduction and efficiency improvement of the solar cell 10.

[0117] It should be noted that not all collector grid lines 111 in the same column must be electrically connected to the same bus grid line 112 via overlapping grid lines 113. For example, some collector grid lines 111 can also be overlapped onto bus grid lines 112 via pads.

[0118] The following is a detailed explanation of the connecting subgrid lines.

[0119] Reference Figure 3 and Figure 5 The connecting sub-gate line 1131 extends along the second direction Y1. That is, the connecting sub-gate line 1131 extends along the direction in which the collector gate lines 111 are spaced apart, so that the connecting sub-gate line 1131 can intersect all the collector gate lines 111 in the same group with a shorter length.

[0120] Optionally, the connecting sub-gate line 1131 passes through the intersecting collector gate lines 111 along the second direction Y1. Therefore, even if the connecting sub-gate line 1131 is slightly offset in the second direction Y1 after printing, it can still intersect with each collector gate line 111 in the same group. In other words, the above design provides a margin for error in the printing accuracy of the connecting sub-gate line 1131 and the collector gate line 111.

[0121] Considering that the length of the overlapping sub-grid line 1132 is positively correlated with the spacing between the connecting sub-grid line 1131 and the busbar line 112, in order to minimize the length of the overlapping sub-grid line 1132, in this application, the connecting sub-grid line 1131 is connected to the end of the collector grid line 111 near the busbar line 112. In this way, the connecting sub-grid line 1131 can be as close as possible to the busbar line 112, making the overlapping sub-grid line 1132 as short as possible, thereby reducing the light-shielding area of ​​the overlapping sub-grid line 1132.

[0122] The following is a detailed description of the overlapping subgrid 1132.

[0123] Reference Figure 3 and Figure 5The overlapping sub-grid line 1132 extends along the first direction X1. That is, since the connecting sub-grid line 1131 and the busbar line 112 are arranged opposite each other in the first direction X1, the overlapping sub-grid line 1132 extending along the first direction X1 can connect the connecting sub-grid line 1131 and the busbar line 112 with a shorter length, so that the light-blocking area of ​​the overlapping sub-grid line 1132 is smaller.

[0124] To allow for proper alignment of the overlapping sub-grid line 1132 and the connecting sub-grid line 1131 during printing, the overlapping sub-grid line 1132 passes through the intersecting connecting sub-grid line 1131 along the first direction X1. Therefore, even if the overlapping sub-grid line 1132 and the connecting sub-grid line 1131 shift during printing, the overlapping sub-grid line 1132 can still overlap the connecting sub-grid line 1131, reducing the incidence of printing grid breakage.

[0125] To allow for proper alignment of the overlapping sub-grid line 1132 with the busbar line 112 during printing, the overlapping sub-grid line 1132 passes through the intersecting busbar line 112 along the first direction X1. In this way, even if the overlapping sub-grid line 1132 slightly shifts during printing, it can still overlap with the busbar line 112, reducing the incidence of printed grid breaks.

[0126] Optionally, the width of the overlapping sub-grid line 1132 at its widest point in the second direction Y1 is greater than the width of the connecting sub-grid line 1131 in the first direction X1. Since the connecting sub-grid line 1131 hardly needs to consider the issue of weld breakage, it is narrower to reduce the overall light-shielding area of ​​the overlapping grid line 113. In other words, this application reduces the number of overlapping sub-grid lines 1132. Although the number of connecting sub-grid lines 1131 is increased, the overall light-shielding area of ​​the overlapping grid line 113 can be further reduced due to the narrower width of the connecting sub-grid lines 1131.

[0127] Optionally, the width of the overlap sub-grid line 1132 in the second direction Y1 narrows away from the intersecting busbar line 112. The intersection of the overlap sub-grid line 1132 and the busbar line 112 has the highest probability of overlapping with the solder ribbon during welding; therefore, the width of the overlap sub-grid line 1132 is widest at this location, indicating that more paste was used for printing at this location, thus containing more electrode material to block the silver etching reaction of the solder ribbon. 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.

[0128] Furthermore, the probability of the overlapping sub-grid line 1132 contacting the solder strip at a position away from the intersecting busbar line 112 is low. Accordingly, the overlapping sub-grid line 1132 narrows in the direction away from the intersecting busbar line 112. The narrowing design helps to reduce the light-blocking area of ​​the overlapping sub-grid line 1132 and the wet weight of the paste during printing.

[0129] Optionally, the first direction X1 is perpendicular to the second direction Y1. Of course, the angle between the first direction X1 and the second direction Y1 can also deviate slightly from 90°, for example, it can be 80°, 85°, 89°, 91°, 95° or 100°.

[0130] Secondly, referring to Figures 6 to 9 This application discloses a solar cell 10, including a cell body 12 and an electrode structure 11 as described in the first aspect, wherein the electrode structure 11 is disposed on the surface of the cell body 12.

[0131] The electrode structure 11 of the solar cell 10, by setting intermittent current collector lines 111, facilitates cost reduction and efficiency improvement by printing narrower linewidth current collector lines 111 using a high aperture ratio printing screen. Simultaneously, the high aperture ratio printing screen also possesses higher structural strength and a longer service life. Furthermore, the electrode structure 11 reduces the number of overlapping sub-grid lines 1132 required when the current collector lines 111 overlap with the busbar lines 112. This reduction in the number of overlapping sub-grid lines 1132 helps reduce the overall light-shielding area of ​​the electrode structure 11 and the wet weight of the printing paste, thereby contributing to cost reduction and efficiency improvement of the solar cell 10.

[0132] In some embodiments, the battery body 12 includes a silicon substrate 121, a doped layer 122, and a first functional film 123. The doped layer 122 and the first functional film 123 are sequentially stacked on the surface of the silicon substrate 121 in a direction away from the silicon substrate 121. The current collector line 112 and the connecting sub-gate line 1131 are disposed on the side of the first functional film 123 away from the doped layer 122. The current collector line 111 and the connecting sub-gate line 1132 pass through the first functional film 123 and make ohmic contact with the doped layer 122.

[0133] In terms of current collection, the lap sub-gate line 1132 of this application is in ohmic contact with the doped layer 122, thereby collecting the current of the doped layer 122, so that the electrode structure 11 can also collect current at the break portion 114, further improving the current collection effect of the electrode structure 11.

[0134] In terms of printing, the connecting sub-grid line 1131 and the bus grid line 112 of this application can be printed using the same printing screen, and the collector grid line 111 and the overlapping sub-grid line 1132 can be printed using the same printing screen. This electrode structure 11 achieves the intermittent overlapping of the collector grid line 111 and the bus grid line 112 without adding an additional printing process.

[0135] More specifically, in the embodiments of this application, the silicon substrate 121 may be an N-type silicon substrate or a P-type silicon substrate. The doped layer 122 may be a diffusion layer, such as a boron diffusion layer or a phosphorus diffusion layer. The doped layer 122 may also be an N-type doped polysilicon layer or a P-type doped polysilicon layer. The first functional film 123 may be a passivation film and / or an antireflection film. The material of the first functional film 123 may be silicon nitride, silicon oxynitride, silicon oxide, or aluminum oxide.

[0136] For example, the battery body 12 is a passivated contact solar cell. When the doped layer 122, the first functional film 123 and the electrode structure 11 are located on the light-receiving surface of the silicon substrate 121, the battery body 12 also includes a dielectric layer 124, a doped polycrystalline silicon layer 125 and a second functional film 126, which are sequentially stacked on the backlight surface of the silicon substrate 121 in a direction away from the silicon substrate 121.

[0137] Of course, the doped layer 122, the first functional film 123, and the electrode structure 11 can also be disposed on the back surface of the silicon substrate 121. In this case, the doped layer 122 is a doped polycrystalline silicon layer 125, and a dielectric layer 124 is also present between the doped layer 122 and the silicon substrate 121.

[0138] As other examples, the battery type of the battery body 12 can also be a heterojunction solar cell or a back contact solar cell, etc.

[0139] Thirdly, embodiments of this application disclose a printing screen assembly for printing the electrode structure described in the first aspect.

[0140] like Figures 10 to 13 As shown, the printing screen assembly includes a first printing screen 20 and a second printing screen 30.

[0141] The first printing screen 20 is provided with a busbar printing groove 21 and a connecting printing groove 22. The extension direction of the busbar printing groove 21 is the third direction Y2. The connecting printing groove 22 is spaced apart from the busbar printing groove 21 in the fourth direction X2 with a spacing of D1. The fourth direction X2 intersects with the third direction Y2. The length of the connecting printing groove 22 in the third direction Y2 is L1.

[0142] The second printing screen 30 has collector grid printing grooves 31 with an opening ratio of 90% to 100%. These grooves extend along the fifth direction X3. N collector grid printing grooves 31 are spaced apart along the sixth direction Y3, intersecting the fifth direction X3. The dimension of each group of collector grid printing grooves 31 in the sixth direction Y3 is D2, where D2 ≤ L1. Multiple groups of collector grid printing grooves 31 are spaced apart along the fifth direction X3. In the fifth direction X3, there is a discontinuity region 32 between each pair of adjacent groups of collector grid printing grooves 31. The width of the discontinuity region 32 in the fifth direction X3 is W, where W / 2 ≤ D1. At least one group of collector grid printing grooves 31 extends M overlapping printing grooves 33 into the spacing region. Here, M is a positive integer, and N is a positive integer greater than M.

[0143] It should be noted that each current collector grid printing groove 31 is configured to print current collector grid lines on the battery body, each overlap printing groove 33 is configured to print overlap sub-grid lines on the break portion, each bus grid printing groove 21 is configured to print bus grid lines on the break portion, and each connection printing groove 22 is configured to print connection sub-grid lines that intersect with the current collector grid lines.

[0144] The technical effects of the printing screen assembly are explained in detail below.

[0145] The printing screen assembly of this application uses a high-aperture-ratio collector grid printing groove 31 to print collector grids with narrower linewidths and better morphology, thereby reducing the light-shielding area and wet weight of the collector grids. Furthermore, the printing screen assembly of this application also uses overlapping sub-grids printed in overlapping printing groove 33 and connecting sub-grids printed in connecting printing groove 22. These overlapping sub-grids and connecting sub-grids form overlapping grids, which electrically connect the collector grids printed at the break points. Since the number of collector grids in a set is less than the required number of overlapping sub-grids, the number of overlapping grids is reduced, resulting in a decrease in the overall light-shielding area and wet weight of the printed electrode structure. A detailed analysis follows:

[0146] In this application, the opening ratio of the current collector grid printing groove 31 is as high as 90% to 100%, indicating that there are fewer obstructions in the current collector grid printing groove 31 and the paste has better throughput. This allows for the printing of current collector grids with narrower line widths 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 is beneficial for improving the conversion efficiency of solar cells.

[0147] To shorten the length of the current collector line printing groove 31 and improve the structural strength of the second printing screen 30, the current collector line printing groove 31 of this application is arranged intermittently, that is, multiple sets of current collector line printing grooves 31 are arranged at intervals along the fifth direction X3. In this way, the second printing screen 30 can print multiple spaced-apart, shorter current collector lines combined together to collect current, instead of continuous, shorter current collector lines. Because the length of the current collector line printing groove 31 of this application is shorter, the structural strength of the second printing screen 30 is stronger. Moreover, when the squeegee applies force to the second printing screen 30, the deformation of the current collector line printing groove 31 is smaller, and the printing offset and coarse grid problems of the current collector line printing groove 31 are correspondingly reduced.

[0148] Based on this, this application also prints busbars on the break between the two sets of collector grids to collect the current from the two broken sets of collector grids. In order to achieve electrical connection between the collector grids and the busbars, this application also prints overlapping sub-grids on the break through the overlapping printing groove 33, and prints connecting sub-grids that intersect with the collector grids through the connecting printing groove 22. The connecting sub-grids and overlapping sub-grids are connected to form overlapping grids, and each set of collector grids is electrically connected to the busbars through the overlapping grids.

[0149] Considering that the overlapping sub-grid lines have a relatively wide width due to the need to prevent weld breakage, the wet weight of the paste during printing the overlapping sub-grid lines is relatively large. This application reduces the wet weight of the paste and the light-shielding area during electrode structure printing by reducing the number of overlapping sub-grid lines printed. The analysis is as follows: This application can print connecting sub-grid lines that intersect with a set of collector grid lines. Specifically, the distance between the connecting printing groove 22 and the bus grid printing groove 21 in the fourth direction X2 is D1. Correspondingly, the distance between the printed connecting sub-grid lines and the bus grid lines is also D1. The width of the discontinuity region 32 between two adjacent sets of collector grid printing grooves 31 is W. It can be understood that the width of the broken part after printing is consistent with the width of the discontinuity region 32. The printing position of the bus grid line is located in the middle of the width direction of the broken part, so the distance between the bus grid line and the set of collector grid lines that are electrically connected is W / 2. When W / 2≤D1 is satisfied, the connecting sub-grid lines printed in the connecting printing groove 22 are located on the setting area of ​​this set of collector grid lines. Furthermore, the length L1 of the connecting printing groove 22 in the third direction Y2 and the dimension D2 of each group of collector grid printing grooves 31 in the sixth direction Y3 satisfy D2≤L1. Thus, the printed connecting sub-grid lines will intersect with N collector grid lines in this group. Moreover, M overlapping sub-grid lines connect this connecting sub-grid line to the bus grid line, where N is a positive integer greater than M. In other words, the number of overlapping sub-grid lines required for a group of collector grid lines to overlap with the bus grid line is less than the number of collector grid lines. This smaller number of overlapping sub-grid lines results in a reduction in the overall light-shielding area and wet weight of the printed electrode structure.

[0150] It should be noted that there is no specific printing order between the first printing screen 20 and the second printing screen 30. For example, the first printing screen 20 first prints the busbar lines and connecting sub-grid lines on the battery body, and then the second printing screen 30 prints the current collector lines and overlapping sub-grid lines on the battery body. Alternatively, the second printing screen 30 first prints the current collector lines and overlapping sub-grid lines on the battery body, and then the first printing screen 20 prints the busbar lines and connecting sub-grid lines on the battery body.

[0151] In this application, the first printing screen 20 can be a wire mesh screen, and the second printing screen 30 can be a fully open steel plate screen, or a fully open steel plate screen with reinforcement structures such as steel wire in some parts.

[0152] Optionally, such as Figure 13 As shown, M is 1 and N is 2. That is, each group of collector grid line printing slots 31 has two collector grid line printing slots 31 and one overlapping printing slot 33. The two printed collector grid lines are overlapped on the bus grid line through an overlapping sub-grid line. According to the analysis in the first aspect, this setting can reduce the transmission loss of the overlapping sub-grid line.

[0153] Based on this, such as Figure 13 As shown, in each group of current collector line printing slots 31, an overlapping printing slot 33 is located between two current collector line printing slots 31 in the sixth direction Y3. In this way, the overlapping printing slot 33 can be separated from the current collector line printing slots 31, maintaining the disconnect between different current collector line printing slots 31, which is beneficial to maintaining the high strength of the second printing screen 30.

[0154] Of course, M and N can also be other values, and this application does not limit them. For example, M is 1 and N is 3; or M is 2 and N is 3; or M is 1 and N is 4.

[0155] In this application, there are several ways to achieve the electrical connection of two adjacent sets of collector grids printed on the stencil assembly to the same bus grid line through overlapping grid lines, as follows:

[0156] In one possible implementation, such as Figure 11 As shown, there are multiple connecting printing slots 22, and every two connecting printing slots 22 spaced apart in the fourth direction X2 form a pair. In a pair of connecting printing slots 22, the orthographic projections of the two connecting printing slots 22 in the fourth direction X2 coincide, and the two connecting printing slots 22 are located on different sides of the same busbar printing slot 21.

[0157] like Figure 13As shown, at least one set of collector grid line printed grooves 31 extends M overlapping printed grooves 33 through the interval area along the fifth direction X3 and extends into the setting area of ​​an adjacent set of collector grid line printed grooves 31.

[0158] In this implementation, the two connecting sub-grid lines printed in a pair of connecting printing grooves 22 and the overlapping sub-grid lines printed in overlapping printing grooves 33 constitute the first type of overlapping grid lines described above. The beneficial effects of the first type of overlapping grid lines have been described in detail in the first aspect and will not be repeated here.

[0159] In another possible implementation, see Figure 14 and Figure 15 There are multiple connecting printed grooves 22, which are arranged in a row along the third direction Y2. In the row of connecting printed grooves 22, each pair of adjacent connecting printed grooves 22 is located on different sides of the same busbar printed groove 21, and each pair of adjacent connecting printed grooves 22 is staggered along the third direction Y2. In the fifth direction X3, overlapping printed grooves 33 extend from the respective setting areas of two adjacent sets of busbar printed grooves 31.

[0160] In this implementation, a connecting sub-grid line printed in a connecting printing groove 22 and an overlapping sub-grid line printed in an overlapping printing groove 33 constitute the second type of overlapping grid line described above. The beneficial effects of the second type of overlapping grid line have been explained in detail in the first aspect and will not be repeated here.

[0161] In some embodiments, referencing the back Figure 11 and Figure 13 The number of busbar printed slots 21 is multiple, and these multiple busbar printed slots 21 are spaced apart along the fourth direction X2. Multiple sets of collector printed slots 31 are arranged in a row along the sixth direction Y3, and multiple rows of collector printed slots 31 are spaced apart along the fifth direction X3. There is a discontinuity region 32 between each pair of adjacent rows of collector printed slots 31. The distance between two adjacent busbar printed slots 21 in the fourth direction X2 is D3, and the length of each row of collector printed slots 31 in the fifth direction X3 is L2; ​​where D3 > L2.

[0162] Correspondingly, multiple busbar printing slots 21 print multiple busbars, and multiple collector grid printing slots 31 print multiple collector grids. A busbar is printed between each pair of adjacent collector grids, meaning that the current collected by two adjacent collector grids is converged to the same busbar, so that the current collection effect of the electrode structure is more efficient.

[0163] In the embodiments of this application, reference is made to Figure 11 and Figure 14The connecting printing groove 22 extends along the third direction Y2. Accordingly, the printed connecting sub-grid lines will extend in the same direction as the bus grid lines. Since the current collector grid lines are arranged in a group at intervals along the extension direction of the bus grid lines, this design helps the connecting sub-grid lines to intersect a group of current collector grid lines with a shorter length, thereby reducing the light-blocking area of ​​the connecting sub-grid lines and the wet weight of the ink during printing.

[0164] Optionally, the third direction Y2 is perpendicular to the fourth direction X2. Of course, the angle between the third direction Y2 and the fourth direction X2 can also deviate slightly from 90°, for example, it can be 80°, 85°, 89°, 91°, 95° or 100°.

[0165] In the embodiments of this application, reference is made to Figure 13 and Figure 15 The overlapping printing groove 33 extends along the fifth direction X3. Accordingly, the overlapping sub-grid lines printed by the overlapping printing groove 33 will extend in the same direction as the current collector lines. Since the current collector lines and the current collector lines are arranged opposite each other in the extension direction of the current collector lines, this design helps the overlapping sub-grid lines to extend to the current collector lines with a shorter length, thereby reducing the light-blocking area of ​​the overlapping sub-grid lines and the wet weight of the ink during printing.

[0166] Optionally, the fifth direction X3 is perpendicular to the sixth direction Y3. Of course, the angle between the fifth direction X3 and the sixth direction Y3 can also deviate slightly from 90°, for example, it can be 80°, 85°, 89°, 91°, 95° or 100°.

[0167] To further reduce the wet weight of the paste during electrode structure printing, such as Figure 13 As shown in this embodiment, the width of the overlap printing groove 33 in the sixth direction Y3 is greater than the width of the connecting printing groove 22 in the fourth direction X2. The wider overlap printing groove 33 prints wider overlap sub-grid lines, which use more paste for printing, resulting in more electrode material to block the silver etching reaction of the solder ribbon and prevent it from being broken by soldering. The narrower connecting printing groove 22 prints narrower connecting sub-grid lines, resulting in a relatively smaller wet weight of paste during the printing of connecting sub-grid lines, which further reduces the wet weight of paste during the printing of the electrode structure.

[0168] Fourthly, embodiments of this application disclose a photovoltaic module comprising a plurality of electrically connected solar cells. At least one of the solar cells has the electrode structure described in the first aspect; or, at least one of the solar cells is the solar cell described in the second aspect; or, the electrode structure of at least one of the solar cells is printed using a screen printing assembly as described in the third aspect.

[0169] Specifically, electrical connection refers to series and / or parallel connection. For example... Figure 16 As shown, the solar cells 10 can be connected to each other via electrical connectors 40. Electrical connectors 40 are, for example, solder strips.

[0170] 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. An electrode structure for a solar cell, characterized in that, include: Multiple collector grid lines are provided, with the extension direction of the collector grid lines being a first direction. The multiple collector grid lines are arranged in a group at intervals along a second direction, and the first direction intersects the second direction. In the first direction, the multiple groups of collector grid lines are arranged at intervals, such that there is a break between each two adjacent groups of collector grid lines. A busbar, at least a portion of which is disposed at the break portion, and which extends along the second direction; as well as The overlapping gate wires, at least one group of the collector gate wires, are electrically connected to the bus gate wires through the overlapping gate wires; each overlapping gate wire includes a connecting sub-gate wire and M overlapping sub-gate wires, in each overlapping gate wire, the connecting sub-gate wire intersects with N collector gate wires in the same group, and the M overlapping sub-gate wires are connected between the connecting sub-gate wire and the bus gate wire, so that the N collector gate wires in the same group are electrically connected to the bus gate wire through the M overlapping sub-gate wires; wherein, M is a positive integer, and N is a positive integer greater than M.

2. The electrode structure according to claim 1, characterized in that, In the first direction, two adjacent sets of collector grids are electrically connected to the same bus grid through the overlapping grid.

3. The electrode structure according to claim 2, characterized in that, The overlapping grid line includes a first type of overlapping grid line, and the number of connecting sub-grid lines in each first type of overlapping grid line is two; In each of the first type of overlapping grid lines, two connecting sub-grid lines are spaced apart along the first direction, and the two connecting sub-grid lines are located on different sides of the same bus grid line. M overlapping sub-grid lines are connected between the two connecting sub-grid lines, and each overlapping sub-grid line also passes through the bus grid line along the first direction. Each of the two connecting sub-grid lines intersects with two sets of collector grid lines adjacent to each other in the first direction, so that the two sets of collector grid lines are electrically connected to the same bus grid line through a first type of overlapping grid line.

4. The electrode structure according to claim 3, characterized in that, The orthographic projections of two connecting sub-grid lines in each of the first type of overlapping grid lines coincide in the first direction, and the orthographic projections of two sets of collector grid lines connected to the same first type of overlapping grid line coincide in the first direction.

5. The electrode structure according to claim 2, characterized in that, The overlapping grid line includes a second type of overlapping grid line, wherein the number of the connecting sub-grid lines in the second type of overlapping grid line is one. This connecting sub-grid line and the bus grid line are spaced apart in the first direction, and M overlapping sub-grid lines are connected between this connecting sub-grid line and the bus grid line. This connecting sub-grid line also intersects with a group of collector grid lines, so that this group of collector grid lines is electrically connected to the bus grid line through a second type of overlapping grid line.

6. The electrode structure according to claim 5, characterized in that, The busbar is connected to a plurality of overlapping busbars of the second type that are spaced apart along the second direction; On the same busbar, the connecting sub-charts of two adjacent second-type overlapping charts are located on different sides of the busbar, and the orthographic projections of these two connecting sub-charts in the first direction are staggered.

7. The electrode structure according to any one of claims 1 to 6, characterized in that, M is 1 and N is 2; In each group of collector grid lines, two collector grid lines are electrically connected to the bus grid line through a lap sub-grid line, and this lap sub-grid line is located between the two collector grid lines in the first direction.

8. The electrode structure according to any one of claims 1 to 6, characterized in that, At least three sets of the collector grid lines are spaced apart along the first direction and have at least two break portions. There are at least two bus grid lines, and each bus grid line is respectively disposed at each break portion. At least one set of the collector grid lines is located between the two bus grid lines. In the first direction, the two ends of each set of collector grids located between the two bus grids are electrically connected between the two bus grids via the overlapping grids.

9. The electrode structure according to any one of claims 1 to 6, characterized in that, Multiple sets of collector grid lines are arranged in a column along the second direction, and multiple columns of collector grid lines are spaced apart along the first direction. A bus grid line is provided between each pair of adjacent columns of collector grid lines. Multiple overlapping grid lines spaced apart along the second direction are connected to each bus grid line. Each set of collector grid lines in two adjacent columns of collector grid lines is electrically connected to the same bus grid line through the overlapping grid lines.

10. The electrode structure according to any one of claims 1 to 6, characterized in that, The connecting sub-grid line extends along the second direction; And / or, the connecting sub-gate lines pass through the intersecting collector gate lines along the second direction; And / or, the connecting sub-grid line is connected to one end of the collector grid line near the bus grid line; And / or, the overlapping subgrid line extends along the first direction; And / or, the overlapping sub-grid line passes through the intersecting connecting sub-grid lines along the first direction; And / or, the overlapping sub-grid line passes through the intersecting busbar lines along the first direction; And / or, the width of the widest point of the overlapping sub-grid line in the second direction is greater than the width of the connecting sub-grid line in the first direction; And / or, the width of the overlapping sub-grid line in the second direction narrows away from the intersecting busbar lines; And / or, the first direction is perpendicular to the second direction; And / or, the width of the collector grid line is 5μm to 20μm.

11. A solar cell, characterized in that, include: Battery body; as well as The electrode structure as described in any one of claims 1 to 10, wherein the electrode structure is disposed on the surface of the battery body.

12. The solar cell according to claim 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 sequentially stacked on the surface of the silicon substrate in a direction away from the silicon substrate. The bus gate line and the connecting sub-gate line are disposed on the side of the first functional film away from the doped layer. The current collector gate line and the overlapping sub-gate line pass through the first functional film and make ohmic contact with the doped layer.

13. A printing screen assembly, characterized in that, include: A first printing screen is provided with a busbar printing groove and a connecting printing groove. The extension direction of the busbar printing groove is a third direction. The connecting printing groove is spaced apart from the busbar printing groove in a fourth direction with a spacing of D1. The fourth direction intersects with the third direction. The length of the connecting printing groove in the third direction is L1. as well as A second printing screen is provided with collector grid printing slots with an opening ratio of 90% to 100%. The collector grid printing slots extend along a fifth direction. N collector grid printing slots are spaced apart in a group along a sixth direction, which intersects the fifth direction. The dimension of each group of collector grid printing slots in the sixth direction is D2, where D2 ≤ L1. Multiple groups of collector grid printing slots are spaced apart along the fifth direction. In the fifth direction, there is a discontinuity region between each two adjacent groups of collector grid printing slots. The width of the discontinuity region in the fifth direction is W, where W / 2 ≤ D1. At least one group of collector grid printing slots extends M overlapping printing slots into the spacing region. Where M is a positive integer and N is a positive integer greater than M.

14. The printing screen assembly according to claim 13, characterized in that, There are multiple connecting printing slots, and every two connecting printing slots spaced apart in the fourth direction constitute a pair; in a pair of connecting printing slots, the orthographic projections of the two connecting printing slots in the fourth direction coincide, and the two connecting printing slots are located on different sides of the same busbar printing slot. At least one set of the current collector wire printing grooves extends M of the overlapping printing grooves through the interval area along the fifth direction and into the setting area of ​​the adjacent set of the current collector wire printing grooves.

15. The printing screen assembly according to claim 13, characterized in that, There are multiple connecting printing slots, and the multiple connecting printing slots are arranged in a row along the third direction upward. In the row of connecting printing slots, each pair of adjacent connecting printing slots is located on different sides of the same busbar printing slot, and each pair of adjacent connecting printing slots are staggered along the third direction upward. In the fifth direction, the overlapping printing grooves extend from the respective areas of the two adjacent sets of the current collector wire printing grooves.

16. The printing screen assembly according to any one of claims 13 to 15, characterized in that, M is 1 and N is 2; In each group of the current collector wire printing slots, one of the overlapping printing slots is located between two of the current collector wire printing slots in the sixth direction.

17. The printing screen assembly according to any one of claims 13 to 15, characterized in that, The number of the busbar printing slots is multiple, and the multiple busbar printing slots are spaced apart along the fourth direction; Multiple sets of the current collector wire printing grooves are arranged in a column along the sixth direction, and multiple columns of the current collector wire printing grooves are spaced apart along the fifth direction. There is a discontinuity area between each pair of adjacent columns of the current collector wire printing grooves. Wherein, the spacing between two adjacent busbar printing slots in the fourth direction is D3, and the length of each column of busbar printing slots in the fifth direction is L2; ​​wherein, D3 > L2.

18. The printing screen assembly according to any one of claims 13 to 15, characterized in that, The connecting printing groove extends along the third direction; And / or, the third direction is perpendicular to the fourth direction; And / or, the overlapping printing groove extends along the fifth direction; And / or, the fifth direction is perpendicular to the sixth direction; And / or, the width of the overlapping printing groove in the sixth direction is greater than the width of the connecting printing groove in the fourth direction.

19. A photovoltaic module, characterized in that, The solar cell comprises a plurality of electrically connected solar cells; at least one of the solar cells has an electrode structure as described in any one of claims 1 to 10; or, at least one of the solar cells is a solar cell as described in claim 11 or 12; or, the electrode structure of at least one of the solar cells is printed using a printing screen assembly as described in any one of claims 13 to 18.

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