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

Abstract

The invention 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 confluence substructure and a plurality of collector grid lines. Each confluence substructure comprises two interconnecting grid lines arranged at an interval and a lap-joint grid line connected between the two interconnecting grid lines, the interval arrangement direction of the two interconnecting grid lines is a first direction, and the extension direction of the interconnecting grid lines is a second direction. The plurality of current collection grid lines are arranged at intervals along a first direction, the current collection grid lines extend along the first direction, and two adjacent current collection grid lines in the first direction form a pair. In at least one pair, the ends, close to each other, of the two current collection grid lines intersect with the two interconnected grid lines in the same confluence substructure. The electrode structure can be used for printing the collector grid lines with narrower line width, and the collector grid lines can be intersected with the interconnected grid lines even if printing deviation occurs in the second direction, so that the conversion efficiency of the solar cell is improved.

Description

TECHNICAL FIELD

[0001] The present 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 module. BACKGROUND

[0002] The conversion efficiency of the solar cell still has room for further improvement. One of the directions for improving the conversion efficiency of the solar cell in the current photovoltaic industry is to focus on the optimization of the electrode structure pattern, for example, the optimization of the pattern of the current collecting grid lines. However, even if the pattern of the current collecting grid lines is optimized, the current collecting grid lines still face the problem of how to be connected with the bus grid lines. The optimized current collecting grid lines are prone to fail to be connected with the bus grid lines due to printing offset, thereby affecting the conversion efficiency of the solar cell. SUMMARY

[0003] Embodiments of the present application disclose a solar cell, an electrode structure of the solar cell, a printing screen assembly and a photovoltaic module, which can improve the conversion efficiency of the solar cell and reduce the production cost of the solar cell.

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

[0005] a bus substructure, the bus substructure comprising two interconnecting grid lines arranged at intervals and a lap grid line connected between the two interconnecting grid lines, the two interconnecting grid lines being arranged at intervals in a first direction, and the interconnecting grid lines extending in a second direction, the first direction intersecting the second direction; and

[0006] a plurality of current collecting grid lines, the plurality of current collecting grid lines being arranged at intervals along the first direction, and the current collecting grid lines extending along the first direction, two current collecting grid lines adjacent to each other in the first direction forming a pair, and in at least one pair of the current collecting grid lines, one end of the two current collecting grid lines close to each other intersecting the two interconnecting grid lines in the same bus substructure.

[0007] In a possible implementation manner of the first aspect, the number of the bus substructures is multiple, and in each bus substructure, the number of the lap grid lines is multiple, and the plurality of lap grid lines are arranged at intervals along the second direction.

[0008] the plurality of pairs of current collecting grid lines being arranged at intervals into two columns along the second direction, each column of current collecting grid lines comprising a plurality of current collecting grid lines arranged at intervals in the second direction, and in the first direction, one end of the two columns of current collecting grid lines close to each other respectively intersecting the two interconnecting grid lines in the same bus substructure, so that the two columns of current collecting grid lines are connected with the same bus substructure.

[0009] In a possible implementation manner of the first aspect, in at least one of the bus substructures, a plurality of the overlap gate lines are equidistantly arranged along the second direction.

[0010] And / or, in at least one column, a plurality of the current collection gate lines are equidistantly arranged along the second direction.

[0011] And / or, in each of the bus substructures, a spacing between two adjacent overlap gate lines in the second direction is D1; in the same column, a spacing between two adjacent current collection gate lines is D2; and D1 / D2 = 0.3-3.

[0012] In a possible implementation manner of the first aspect, a plurality of the bus substructures are arranged at intervals along the first direction.

[0013] At least three columns of the current collection gate lines are arranged at intervals along the first direction, an Nth column and an N+1th column of the current collection gate lines are connected with an Nth bus substructure, and an N+1th column of the current collection gate lines and an N+2th column of the current collection gate lines are connected with an N+1th bus substructure; wherein N is a positive integer.

[0014] In a possible implementation manner of the first aspect, the overlap gate line extends along the first direction, and two ends of the overlap gate line in the first direction are connected with two interconnection gate lines respectively; the first direction is perpendicular to the second direction.

[0015] In a possible implementation manner of the first aspect, the overlap gate line is in a rectangular shape.

[0016] Alternatively, along the first direction, the overlap gate line includes an overlap segment in a middle part, and narrowing segments extending from opposite ends of the overlap segment in a direction away from the overlap segment; a width of the narrowing segment in the second direction narrows in the direction away from the overlap segment, and a maximum width of the narrowing segment in the second direction is less than or equal to a width of the overlap segment.

[0017] Alternatively, along the first direction, the overlap gate line includes an overlap segment in a middle part, narrowing segments extending from opposite ends of the overlap segment in a direction away from the overlap segment, and a connecting segment connected with ends of the narrowing segments away from the overlap segment; a width of the narrowing segment in the second direction narrows in the direction away from the overlap segment, a maximum width of the narrowing segment in the second direction is less than or equal to a width of the overlap segment, and a width of the connecting segment in the second direction is equal to a narrowest width of the narrowing segment.

[0018] In a possible implementation manner of the first aspect, in at least one of the current collection gate lines, at least one of the current collection gate lines passes through the intersecting interconnection gate line along the first direction.

[0019] In a possible implementation manner of the first aspect, the current collecting grid line has an extension section, and the extension section extends into two of the interconnecting grid lines of the same current collecting substructure;

[0020] In the first direction, a length of the extension section is L1, and a total length of the current collecting grid line is L2, and L1 / L2 = 0.1% to 10%.

[0021] In a possible implementation manner of the first aspect, the current collecting substructure is composed of two of the interconnecting grid lines arranged at intervals and the overlap grid line connected between the two interconnecting grid lines.

[0022] In a possible implementation manner of the first aspect, a width of the interconnecting grid line in the first direction is W1, and a width of the current collecting grid line in the second direction is W2, and W2:W1 = 1:(1 to 3).

[0023] And / or, a width of the interconnecting grid line in the first direction is W1, and a width of the overlap grid line at the widest part in the second direction is W3, and W1:W3 = 1:(1 to 7).

[0024] In a second aspect, an embodiment of the present application discloses a solar cell, comprising:

[0025] a cell body; and

[0026] an electrode structure as described in the first aspect, the electrode structure being arranged on a surface of the cell body.

[0027] In a possible implementation manner of the second aspect, the cell body comprises a silicon substrate, a doped layer, and a first functional film, the doped layer and the first functional film being stacked in sequence on the silicon substrate in a direction away from the silicon substrate, the interconnecting grid line and the overlap grid line being arranged on a side of the first functional film away from the silicon substrate, and the current collecting grid line being in ohmic contact with the doped layer through the first functional film.

[0028] In a third aspect, an embodiment of the present application discloses a printing screen assembly, comprising:

[0029] a first printing screen, the first printing screen being provided with printing groove structures, each of the printing groove structures comprising two interconnecting grid line printing grooves arranged at intervals and an overlap grid line printing groove connected between the two interconnecting grid line printing grooves, a direction in which the two interconnecting grid line printing grooves are arranged at intervals being a third direction, and a distance between the two interconnecting grid line printing grooves in the third direction being D3; an extension direction of the interconnecting grid line printing groove being a fourth direction, and the third direction intersecting the fourth direction; and

[0030] The second printing screen has a plurality of current collecting grid line printing grooves, and the opening rate of at least one of the current collecting grid line printing grooves is 90% to 100%; the plurality of current collecting grid line printing grooves are arranged at intervals along a fifth direction, and extend along the fifth direction, two current collecting grid line printing grooves adjacent in the fifth direction form a pair, and the interval of the two current collecting grid line printing grooves of the same pair in the fifth direction is D4; wherein D4≤D3.

[0031] In a possible implementation manner of the third aspect, in each of the printing groove structures, the number of the overlap grid line printing grooves is a plurality, and the plurality of overlap grid line printing grooves are arranged at intervals along the fourth direction.

[0032] The plurality of pairs of current collecting grid line printing grooves are arranged at intervals along a sixth direction into two rows, each row of current collecting grid line printing grooves includes a plurality of current collecting grid line printing grooves arranged at intervals along the sixth direction, and the sixth direction intersects the fifth direction.

[0033] In a possible implementation manner of the third aspect, the number of the printing groove structures is a plurality, and the plurality of printing groove structures are arranged at intervals along the third direction; the interval of two adjacent printing groove structures in the third direction is D5.

[0034] The at least three rows of current collecting grid line printing grooves are arranged at intervals along the fifth direction, and the size of at least one row of current collecting grid line printing grooves in the fifth direction is D6; wherein D5

[0035] In a possible implementation manner of the third aspect, the overlap grid line printing groove extends along the third direction, and the two ends of the overlap grid line printing groove in the third direction are connected to two interconnection grid line printing grooves respectively, and the third direction is perpendicular to the fourth direction.

[0036] In a possible implementation manner of the third aspect, the pattern of the overlap grid line printing groove is a rectangle.

[0037] Alternatively, along the third direction, the overlap grid line printing groove includes an overlap segment printing part located in the middle, and a narrowing segment printing part extending from opposite ends of the overlap segment printing part in a direction away from the overlap segment printing part; the width of the narrowing segment printing part in the fourth direction narrows in the direction away from the overlap segment printing part, and the maximum width of the narrowing segment printing part in the fourth direction is less than or equal to the width of the overlap segment printing part.

[0038] Alternatively, along the third direction upwards, the overlapping grid line printing groove includes an overlapping section printing portion located in the middle, a narrowing section printing portion extending from the opposite end of the overlapping section printing portion in a direction away from the overlapping section printing portion, and a connecting section printing portion connected to the end of the narrowing section printing portion away from the overlapping section printing portion; the width of the narrowing section printing portion in the fourth direction narrows in a direction away from the overlapping section printing portion, the maximum width of the narrowing section printing portion in the fourth direction is less than or equal to the width of the overlapping section printing portion, and the width of the connecting section printing portion in the fourth direction is equal to the width at the narrowest point of the narrowing section printing portion.

[0039] 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, at least one of the solar cells being printed by a printing screen assembly as described in the third aspect.

[0040] Compared with the prior art, the beneficial effects of this application are:

[0041] This electrode structure optimizes the pattern of the collector grid lines, resulting in narrower linewidths and better-shaped collector grid lines, thus contributing to cost reduction and efficiency improvement in solar cells. Furthermore, the structure incorporates two interconnecting grid lines intersecting with two discontinuous collector grid lines. This allows the current from these two collector grid lines to converge through the interconnecting grid lines to the overlapping grid lines. The interconnecting grid lines extend along a second direction, ensuring that even if the collector grid lines experience printing misalignment in this direction, they can still intersect with the interconnecting grid lines to achieve current convergence. This improves the printing yield of the collector grid lines, enhances the current collection effect of the electrode structure, and ultimately improves the conversion efficiency of solar cells using this electrode structure.

[0042] Regarding the optimization of the collector grid pattern, the collector grid lines in this application are intermittently arranged, with multiple collector grid lines spaced apart along a first direction. In other words, in order to collect current over a certain area, related technologies use continuous, long collector grid lines for current collection, while the electrode structure in this application utilizes multiple intermittent, shorter collector grid lines combined together for current collection.

[0043] Because the printed pattern on the printing screen matches the pattern of the collector lines, meaning the collector line printing slots on the printing screen are also intermittently arranged, and the length of each individual collector line printing slot is relatively short. Since the collector line printing slots are the weakest areas on the printing screen, the structural strength of the printing screen is negatively correlated with the length of the collector line printing slots. It can be understood that the shorter the length of the collector line printing slots, the shorter the weak area on the printing screen, the stronger the structural strength of the printing screen, and the longer its service life. Especially for high-aperture printing screens, the shorter the collector line printing slots, the more significant the improvement in structural strength and service life. Furthermore, shorter collector line printing slots result in less deformation during printing, thus reducing printing misalignment and excessively thick grid lines caused by collector line deformation.

[0044] In other words, this application optimizes the pattern of the collector grid lines, enabling high aperture ratio printing screens to print collector grid lines with narrower linewidths and better morphology. Simultaneously, the high aperture ratio printing screens also possess higher structural strength and a longer service life. Narrower linewidth collector grid lines result in a smaller light-blocking area, which helps improve the conversion efficiency of solar cells using this electrode structure. Furthermore, narrower linewidth collector grid lines result in lower wet weight of the printing paste, thus helping to reduce the manufacturing cost of solar cells.

[0045] To collect the current from the collector grid lines, the electrode structure of this application further includes a bus structure. The bus structure includes two spaced-apart interconnecting grid lines and an overlapping grid line connecting the two interconnecting grid lines. The two interconnecting grid lines are spaced apart in a first direction. In at least one pair of collector grid lines, the ends of the two collector grid lines closest to each other intersect with two interconnecting grid lines in the same bus structure. This allows for a sufficiently wide spacing between the two collector grid lines, which is beneficial for enhancing the structural strength of the printing screen.

[0046] Based on this, since the extension direction of the interconnect grid lines is the second direction, even if the two collector grid lines are printed off in the second direction, they can still intersect with the two interconnect grid lines respectively, thus enabling the current to continue to be transmitted through the interconnect grid lines. In other words, the interconnect grid lines help improve the printing yield of the collector grid lines, resulting in better current collection of the electrode structure, and thus improving the conversion efficiency of the solar cell using this electrode structure. Attached Figure Description

[0047] 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.

[0048] Figure 1 This is a schematic diagram of the electrode structure of a solar cell;

[0049] Figure 2 This is a schematic diagram of the electrode structure of a solar cell disclosed in an embodiment of this application;

[0050] Figure 3 for Figure 2 A magnified view of a portion of region I shown in the diagram;

[0051] Figure 4 for Figure 2 Another enlarged view of region I shown in the diagram;

[0052] Figure 5 for Figure 2 Another enlarged view of region I shown in the diagram;

[0053] Figure 6 for Figure 2 Another enlarged view of region I shown in the diagram;

[0054] Figure 7 This is a schematic diagram of the structure of the overlapping grid line disclosed in the embodiments of this application;

[0055] Figure 8 This is a cross-sectional view of a solar cell (collector grid area) disclosed in an embodiment of this application;

[0056] Figure 9 This is a cross-sectional view of a solar cell (overlapping grid area) disclosed in an embodiment of this application;

[0057] Figure 10 This is a cross-sectional view of a solar cell (interconnect grid area) disclosed in an embodiment of this application;

[0058] Figure 11 This is a schematic diagram of the structure of the first printing screen disclosed in the embodiments of this application;

[0059] Figure 12 This is a schematic diagram of the structure of the second printing screen disclosed in an embodiment of this application;

[0060] Figure 13 This is a schematic diagram of the overlapping grid line printing groove disclosed in an embodiment of this application.

[0061] Explanation of reference numerals in the attached figures:

[0062] 10. Solar cell; 11. Electrode structure; 12. Busbar structure; 121. Interconnect grid line; 1211. Interconnect sub-grid line; 122. Overlap grid line; 1221. Overlap section; 1222. Narrowing section; 1223. Connecting section; 13. Current collector grid line; 131. Extension section; 14. Cell body; 141. Silicon substrate; 142. Doped layer; 143. First functional film; 144. Interface passivation layer; 145. Doped polycrystalline silicon layer; 146. Second functional film; 15. Busbar line; X1, First direction; Y1, Second direction;

[0063] 20. First printing screen; 21. Printing groove structure; 211. Interconnecting grid line printing groove; 212. Overlapping grid line printing groove; 2121. Overlapping section printing section; 2122. Narrowing section printing section; 2123. Connecting section printing section; X2. Third direction; Y2. Fourth direction;

[0064] 30. Second printing screen; 31. Collector grid printing groove; X3, fifth direction; Y3, sixth direction. Detailed Implementation

[0065] 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.

[0066] In this application, the terms "upper," "inner," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0067] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0068] Furthermore, 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 these terms in this application based on the specific circumstances.

[0069] 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.

[0070] 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.

[0071] Narrow linewidth collector lines are difficult to print using wire mesh because: wire mesh is made of woven steel wire and coated with an adhesive layer. During the fabrication of the printing slots, only the adhesive layer in the slot area is removed. Therefore, steel wires remain in the printing slots, resulting in an opening rate of only 80%. These steel wires affect ink penetration. When wire mesh is used to print narrow collector lines, poor ink penetration leads to printing abnormalities and poor line morphology. In general, wire mesh is not suitable for printing narrow linewidth collector lines.

[0072] High aperture ratio printing screens are more suitable for printing narrower collector lines. This is because, during the fabrication of the printing tank, all or most of the screen material within the tank area is removed, resulting in an aperture ratio of 90%–100% (including endpoints). This aperture ratio can be measured using a screen inspection instrument. A higher aperture ratio indicates fewer, or even no, solid structures within the printing tank area, leading to less ink obstruction caused by solid structures and better ink penetration. Better ink penetration results in better printed morphology of the collector lines. Therefore, high aperture ratio printing screens can print narrower collector lines while maintaining a good morphology.

[0073] However, the high opening ratio of the printing groove also means that it lacks internal solid structures such as steel wires for structural reinforcement, making the printing groove a weak area on a high-opening-ratio printing screen. Understandably, the longer the printing groove, the weaker the structural strength of the high-opening-ratio printing screen, and the shorter its lifespan. On the other hand, because the printing groove lacks solid structures like steel wires for tension, when the squeegee applies force to the high-opening-ratio printing screen, the printing groove is prone to deformation, resulting in positional changes and widening of the opening, leading to printing abnormalities such as printing misalignment and coarse lines. The longer the printing groove, the more numerous and severe these printing abnormalities become.

[0074] The inventors discovered through research that, for exampleFigure 1 As shown, in the electrode structure 11 of the solar cell 10, when the current collector line 13 is designed as an intermittent current collector line 13, the length of the current collector line 13 can be shortened, thereby improving the structural strength and service life of the high aperture ratio printing screen and reducing printing defects. More specifically, multiple intermittent, shorter current collector lines 13 are combined together to collect and transmit current, which is equivalent to breaking a continuous, long current collector line 13 into multiple intermittent, shorter current collector lines 13. Since the printed pattern on the printing screen is consistent with the pattern of the current collector line 13 on the solar cell 10, the length of the printing groove of the current collector line 13 is also shortened. According to the above analysis, a shorter length of the current collector line 13 is beneficial to improving the structural strength of the high aperture ratio printing screen and reducing printing defects.

[0075] To collect the current from the intermittent collector lines 13, one implementation involves placing a busbar 15 between the two intermittent collector lines 13. However, since the spacing between two adjacent intermittent collector lines 13 needs to reach a certain value to effectively improve the structural strength of the printing screen, the width of the busbar 15 is much smaller than the spacing between the two collector lines 13. If the busbar 15 is printed directly between the two collector lines 13, it will be impossible to connect the two collector lines 13 simultaneously. Therefore, an overlapping busbar 122 intersecting with the busbar 15 needs to be provided on the busbar 15, with the overlapping busbar 122 extending in the same direction as the collector lines 13. During printing, the busbar 15 and the overlapping busbar 122 are printed together first, followed by the intermittent collector line 13. The end of the collector line 13 needs to be printed precisely on the overlapping busbar 122. The overlapping busbar 122 connects the collector line 13 and the busbar 15, allowing the current from the collector line 13 to be collected in the busbar 15 through the overlapping busbar 122. The process of printing the collector line 13 and the overlapping busbar 122 is equivalent to first printing a straight line, and then printing a straight line extending in the same direction on top of that straight line, ensuring that the two lines overlap. This requires extremely high printing precision. In other words, if the printing offset of the collector line 13 is large, the collector line 13 will break away from the overlapping busbar 122, and the current from the collector line 13 cannot be collected in the busbar 15, thus affecting the conversion efficiency of the solar cell 10.

[0076] Based on the above analysis, this application provides an electrode structure for a solar cell. By optimizing the pattern of the collector grid lines, this electrode structure can utilize a high aperture ratio printing screen to print narrower linewidth collector grid lines, which is beneficial for cost reduction and efficiency improvement in solar cells. Furthermore, the high aperture ratio printing screen has strong structural strength and a long service life. In addition, the electrode structure also uses two interconnecting grid lines intersecting with two discontinuous collector grid lines to collect the current from these two collector grid lines to the overlapping grid lines. The interconnecting grid lines extend along a second direction, ensuring that even if the collector grid lines are offset in the second direction, they can still intersect with the interconnecting grid lines, achieving current convergence and improving current transmission efficiency, thereby enhancing the conversion efficiency of the solar cell.

[0077] The technical solution of the present invention will now be described in conjunction with the embodiments and accompanying drawings.

[0078] Firstly, see [the following] Figure 2 and Figure 3 This application discloses an electrode structure 11 of a solar cell 10, including a busbar structure 12 and multiple collector grid lines 13.

[0079] The bus structure 12 includes two interconnecting gate lines 121 spaced apart and an overlapping gate line 122 connecting the two interconnecting gate lines 121. The two interconnecting gate lines 121 are spaced apart in a first direction X1, and the extension direction of the interconnecting gate lines 121 is a second direction Y1. The first direction X1 and the second direction Y1 intersect.

[0080] Multiple collector gate lines 13 are spaced apart along a first direction X1 and extend along the first direction X1. Two adjacent collector gate lines 13 in the first direction X1 form a pair. In at least one pair of collector gate lines 13, the ends of the two collector gate lines 13 closest to each other intersect with two interconnect gate lines 121 in the same bus structure 12.

[0081] The beneficial effects of the electrode structure 11 of this application will be described in detail below.

[0082] The electrode structure 11 of this application optimizes the pattern of the collector grid lines 13, which facilitates the printing of collector grid lines 13 with narrower linewidths and better morphology, thereby contributing to cost reduction and efficiency improvement of the solar cell 10. Furthermore, the electrode structure 11 intersects two discontinuous collector grid lines 13 with two interconnecting grid lines 121, allowing the current from these two collector grid lines 13 to converge to the overlapping grid lines 122 via the interconnecting grid lines 121. The interconnecting grid lines 121 extend along the second direction Y1, ensuring that even if the collector grid lines 13 are printed off-center in the second direction Y1, they can still intersect with the interconnecting grid lines 121 to achieve current convergence. This improves the printing yield of the collector grid lines 13, resulting in better current collection performance of the electrode structure 11 and ultimately enhancing the conversion efficiency of the solar cell 10 using this electrode structure 11.

[0083] Regarding the optimization of the collector grid line 13 pattern, the collector grid line 13 in this application is intermittently arranged, with multiple collector grid lines 13 spaced apart along the first direction X1. In other words, in order to collect current over a certain area, related technologies use continuous, long collector grid lines 13 for current collection, while the electrode structure 11 in this application utilizes multiple intermittent, shorter collector grid lines 13 combined together for current collection.

[0084] Since the printed pattern on the printing screen is consistent with the pattern of the collector lines 13, in other words, the printing grooves of the collector lines 13 on the printing screen are also intermittently arranged, and the length of each individual collector line 13 printing groove is relatively short. Because the collector lines 13 printing grooves are weak areas on the printing screen, the structural strength of the printing screen is negatively correlated with the length of the collector lines 13 printing grooves. It can be understood that the shorter the length of the collector lines 13 printing grooves, the shorter the weak area on the printing screen, the stronger the structural strength of the printing screen, and the longer the service life of the printing screen. Especially for high-aperture printing screens, the shorter the collector lines 13 printing grooves, the more significant the improvement in structural strength and service life. Moreover, the shorter the collector lines 13 printing grooves, the less deformation they undergo during printing, thus reducing printing offset and excessively thick grid lines caused by the deformation of the collector lines 13 printing grooves.

[0085] In other words, this application optimizes the pattern of the collector grid lines 13, enabling the high aperture ratio printing screen to print collector grid lines 13 with narrower linewidths and better morphology. Simultaneously, the high aperture ratio printing screen also possesses higher structural strength and a longer service life. The narrower linewidth collector grid lines 13 result in a smaller light-blocking area, which is beneficial for improving the conversion efficiency of the solar cell 10. Furthermore, the narrower linewidth collector grid lines 13 result in lower wet weight of the printing paste, thus helping to reduce the manufacturing cost of the solar cell 10.

[0086] To collect the current from the collector grid lines 13, the electrode structure 11 of this application further includes a bus structure 12. The bus structure 12 includes two spaced-apart interconnect grid lines 121 and an overlapping grid line 122 connecting the two interconnect grid lines 121. The two interconnect grid lines 121 are spaced apart in a first direction X1. In at least one pair of collector grid lines 13, the ends of the two collector grid lines 13 closest to each other intersect with two interconnect grid lines 121 in the same bus structure 12. In this way, there can be a sufficiently wide spacing between the two collector grid lines 13, which is beneficial to enhancing the structural strength of the printing screen.

[0087] Based on this, since the extension direction of the interconnect gate line 121 is the second direction Y1, even if the two collector gate lines 13 are printed off in the second direction Y1, they can still intersect with the two interconnect gate lines 121 respectively, and thus the current can continue to be transmitted through the interconnect gate line 121 to the overlapping gate line 122. In other words, the interconnect gate line 121 helps to improve the printing yield of the collector gate line 13, and the current collection effect of the electrode structure 11 is better, thereby improving the conversion efficiency of the solar cell 10 using this electrode structure 11.

[0088] In summary, this application optimizes the pattern of the collector grid line 13, enabling the printing of narrower linewidth collector grid lines 13 using a high aperture ratio printing screen. Simultaneously, the collector grid line 13 exhibits a better morphology, which is beneficial for cost reduction and efficiency improvement in the solar cell 10. Furthermore, by incorporating interconnect grid lines 121 into the electrode structure 11, even if the collector grid line 13 experiences printing offset in the second direction Y1, it can still intersect with the interconnect grid lines 121 to achieve current convergence. This improves the printing yield of the collector grid line 13, enhances the current collection effect of the electrode structure 11, and ultimately improves the conversion efficiency of the solar cell 10.

[0089] The collector grid and busbar structure of this application are described in further detail below.

[0090] In some embodiments, see Figure 4 Multiple pairs of collector grid lines 13 are arranged in two columns at intervals along the second direction Y1. Each column of collector grid lines 13 includes multiple collector grid lines 13 spaced apart along the second direction Y1. In this embodiment, the collector grid lines 13 are arranged in columns so that they are distributed on the surface of the solar cell along the second direction Y1, thereby better collecting the current from the surface of the solar cell.

[0091] Based on this, such as Figure 4As shown, in the first direction X1, the ends of the two columns of collector grid lines 13 closest to each other intersect with two interconnecting grid lines 121 in the same bus structure 12, so that the two columns of collector grid lines 13 are connected to the same bus structure 12. In this way, any one of the bus structures 12 can collect the current of the two columns of collector grid lines 13, thereby improving the current collection efficiency of the bus structure 12.

[0092] To distribute the current in each column of collector grid lines 13 and shorten the current transmission path of each collector grid line 13, such as Figure 4 As shown, there are multiple bus structures 12, and each bus structure 12 contains multiple overlapping gate lines 122, which are spaced apart along the second direction Y1. Thus, the current collection path on the collector gate lines 13 is roughly as follows: the current of each collector gate line 13 can first be transmitted to the interconnecting gate line 121 connected to it, and then the interconnecting gate line 121 transmits the current to the overlapping gate line 122 that is closer to the collector gate line 13. Since the collector gate lines 13 and the overlapping gate lines 122 are spaced apart along the second direction Y1, each collector gate line 13 has an overlapping gate line 122 that is close to it, which helps to shorten the current transmission path when the collector gate lines 13 are collecting current. Furthermore, the current collected by each column of collector gate lines 13 is equivalent to being split into multiple overlapping gate lines 122 through one interconnecting gate line 121, which helps to reduce the current intensity in each overlapping gate line 122. Since current intensity and current transmission loss are directly proportional, when the current intensity of the overlapping grid line 122 decreases, the current transmission loss decreases, thereby improving the conversion efficiency of the solar cell 10 using this electrode structure 11.

[0093] Of course, when the collector grid line 13 is printed directly on the overlapping grid line 122, the collector grid line 13 can also directly transmit current to the overlapping grid line 122. In this case, the multiple overlapping grid lines 122 spaced apart in the second direction Y1 still help to distribute the current of each column of collector grid lines 13. That is to say, in this application, the current of the collector grid line 13 does not necessarily have to pass through the interconnecting grid line 121 before being transmitted to the overlapping grid line 122.

[0094] Furthermore, such as Figure 4 As shown, in at least one column of collector grid lines 13, multiple collector grid lines 13 are arranged at equal intervals along the second direction Y1. The equidistant arrangement of the collector grid lines 13 allows current to be collected uniformly on the surface of the solar cell 10, reducing current transmission losses. Since the collector grid lines 13 cause shading on the surface of the solar cell 10, the equidistant arrangement of the collector grid lines 13 also ensures that the surface of the solar cell 10 receives more uniform illumination, which is beneficial for improving the conversion efficiency of the solar cell 10 using this electrode structure 11.

[0095] Based on this, such as Figure 4As shown, in at least one busbar structure 12, multiple overlapping gate lines 122 are equidistantly arranged along the second direction Y1. The equidistantly arranged overlapping gate lines 122 divide the interconnecting gate line 121 into multiple interconnecting sub-gate lines 1211 of equal length. Both ends of the interconnecting sub-gate line 1211 are connected to the overlapping gate line 122. When the collector gate line 13 intersects with the interconnecting sub-gate line 1211, the current transmission path between the collector gate line 13 and the overlapping gate line 122 will not exceed the length of the interconnecting sub-gate line 1211 in the second direction Y1, thus maintaining the current transmission path between the collector gate line 13 and the overlapping gate line 122 within a relatively short range. Since current transmission loss is inversely proportional to the length of the current transmission path, the equidistantly arranged overlapping gate lines 122 help reduce current transmission loss, thereby improving the conversion efficiency of the solar cell 10. On the other hand, the equidistantly arranged overlapping gate lines 122 enable the surface of the solar cell 10 to receive more uniform illumination, which is beneficial to improving the conversion efficiency of the solar cell 10.

[0096] Optionally, such as Figure 4 As shown, in each busbar structure 12, the spacing between two adjacent overlapping gate lines 122 in the second direction Y1 is D1. In the same column, the spacing between two adjacent collector gate lines 13 is D2. Wherein, D1 / D2 = 0.3 to 3, for example, D1 / D2 = 0.3, 1, 2, or 3. When the spacing D1 of two adjacent overlapping gate lines 122 in the second direction Y1 satisfies the above-mentioned D1 / D2 ratio range, the spacing of the overlapping gate lines 122 and the spacing of the collector gate lines 13 are matched to ensure a low current density in each overlapping gate line 122, thereby reducing the current transmission loss of the overlapping gate lines 122. Furthermore, the spacing between the two overlapping gate lines 122 is not too dense, to avoid a large shading area due to excessively dense overlapping gate lines 122.

[0097] More preferably, D1 / D2 = 1. In this case, in each busbar structure 12, the spacing D1 between two adjacent overlapping gate lines 122 in the second direction Y1 is equal to the spacing D2 between two adjacent collector gate lines 13 in the same column. Each overlapping gate line 122 transmits current to each pair of collector gate lines 13, further shortening the current transmission path. Under ideal printing alignment, each collector gate line 13 overlaps with each overlapping gate line 122, allowing the current in each collector gate line 13 to be directly conducted to each overlapping gate line 122.

[0098] Understandably, to ensure good structural strength of the printing screen, the current collector lines are relatively short in the first direction, for example, 5mm to 10mm in length. However, the size of the solar cell in the first direction is often several times the length of the current collector lines, for example, exceeding 100mm. To ensure that the shorter current collector lines are distributed over most of the solar cell's surface in the first direction, such as... Figure 5As shown, in some embodiments, at least three columns of collector grid lines 13 are spaced apart along a first direction X1. In this way, the collector grid lines 13 will be distributed along the first direction X1 over most of the surface of the solar cell to collect the current from the surface of the solar cell more efficiently.

[0099] Based on this, such as Figure 5 As shown, multiple bus structures 12 are spaced apart along a first direction X1. The Nth and N+1th collector grid lines 13 are connected to the Nth bus structure 12, and the N+1th and N+2th collector grid lines 13 are connected to the N+1th bus structure 12. Here, N is a positive integer, such as 1, 2, or 3, and this embodiment does not limit this value.

[0100] Any one of the bus structures 12 can combine current through two columns of collector grid lines 13. Two bus structures 12 are connected to the two ends of a portion of the collector grid lines 13, allowing the current in this portion of the collector grid lines 13 to be combined into the two bus structures 12. This further shortens the current transmission path of this portion of the collector grid lines 13. When a break occurs between the two ends of this portion of the collector grid lines 13, the broken portion of the collector grid lines 13 remains connected to one of the bus structures 12, thus allowing current to continue to be transmitted to that bus structure 12.

[0101] The collector grid is described in detail below.

[0102] In some embodiments, see Figure 6 In the same pair of collector gate lines 13, at least one collector gate line 13 passes through the intersecting interconnect gate lines 121 along a first direction X1. The term "passes through" means that the collector gate line 13 extends into the interconnect gate line 121 from one side and protrudes from the other side of the interconnect gate line 121, forming a cross-shaped structure or an X-shaped structure.

[0103] In other words, in the same pair of collector gate lines 13, the spacing between the two collector gate lines 13 in the first direction X1 is smaller than the spacing between the two interconnect gate lines 121 of the same bus structure 12 in the first direction X1, such that at least one collector gate line 13 passes through the intersecting interconnect gate lines 121 along the first direction X1. The above design provides leeway for the printing offset of the collector gate lines 13, so that when the printing offset of this pair of collector gate lines 13 occurs in the first direction X1, the collector gate lines 13 can still intersect with the interconnect gate lines 121.

[0104] Furthermore, such as Figure 6As shown, the collector grid line 13 has an extension 131 that extends between two interconnect grid lines 121 of the same busbar structure 12. It is understood that the extension 131 is the portion of the collector grid line 13 that extends between the two interconnect grid lines 121 after passing through the intersecting interconnect grid lines 121. Optionally, in the first direction X1, the length of the extension 131 is L1, and the total length of the collector grid line 13 is L2, where L1 / L2 = 0.1% to 10%, for example, L1 / L2 = 0.1%, 1%, 3%, 5%, 7%, or 10%. When the length L1 of the extension 131 satisfies the above L1 / L2 range, the length L1 of the extension 131 provides sufficient allowance for the printing offset of the collector grid line 13 in the first direction X1. The extension 131 is also not excessively long, so that the length of the collector grid line 13 is shorter, resulting in a lower light-blocking area and a lower wet weight of the paste during printing.

[0105] The bus structure in this application will be described in detail below.

[0106] In some embodiments, see Figure 6 The busbar structure 12 consists of two spaced interconnecting gate lines 121 and an overlapping gate line 122 connecting the two interconnecting gate lines 121. As a result, the structure of the busbar structure 12 is relatively simple, which allows the busbar structure 12 to have a lower light-blocking area and a lower wet weight of the paste during printing.

[0107] Of course, in other embodiments, the busbar structure may have other components.

[0108] The interconnect gate lines of the bus structure are described in detail below.

[0109] like Figure 6 As shown, optionally, the width of the interconnect gate line 121 in the first direction X1 is W1, and the width of the collector gate line 13 in the second direction Y1 is W2, where W2:W1 = 1:(1~3). When the width W1 of the interconnect gate line 121 in the first direction X1 satisfies the above-mentioned W2:W1 ratio range, the width W1 of the interconnect gate line 121 in the first direction X1 is sufficiently wide. Since the resistivity is inversely proportional to its width, the interconnect gate line 121 has a low resistivity, thereby resulting in low current transmission loss. The interconnect gate line 121 is also not excessively wide, thus the interconnect gate line 121 has a low light-shielding area and a low wet weight of the paste during printing.

[0110] More specifically, the width W1 of the interconnect gate line 121 in the first direction X1 can be 10μm to 30μm, for example, 10μm, 20μm or 30μm, and the width W2 of the collector gate line 13 in the second direction Y1 can be 8μm to 20μm, for example, 8μm, 16μm or 20μm.

[0111] Optionally, the width of the interconnecting gate line 121 in the first direction X1 is W1, and the width of the overlapping gate line 122 at its widest point in the second direction Y1 is W3, where W1:W3 = 1:(1~7), for example, W1:W3 = 1:1, 1:3, 1:5, or 1:7. When the width W2 of the overlapping gate line 122 in the second direction Y1 satisfies the above-mentioned W1:W3 ratio range, the width range of the overlapping gate line 122 is sufficiently wide, resulting in a lower resistivity for the overlapping gate line 122. This width range of the overlapping gate line 122 can also better block the silver etching reaction of the conductive wire. Furthermore, the overlapping gate line 122 is not excessively wide, thus resulting in a lower light-shielding area for the overlapping gate line 122 and a lower wet weight of the paste during printing.

[0112] More specifically, the width W3 of the lap grid line 122 at its widest point in the second direction Y1 is 20 μm to 70 μm, for example, 20 μm, 45 μm or 70 μm.

[0113] The overlapping grid lines of the busbar structure are described in detail below.

[0114] See Figure 6 Considering that the two interconnecting gate lines 121 are spaced apart in the first direction X1, in order to shorten the length of the overlapping gate line 122, in some embodiments, the overlapping gate line 122 extends along the first direction X1, and the two ends of the overlapping gate line 122 in the first direction X1 are respectively connected to the two interconnecting gate lines 121. Wherein, the first direction X1 is perpendicular to the second direction Y1.

[0115] In this way, the required length of the overlapping gate line 122 is shorter. As long as the length of the overlapping gate line 122 is not less than the spacing between the two interconnecting gate lines 121, it can be connected between the two interconnecting gate lines 121. The shorter length of the overlapping gate line 122 helps to reduce the light-blocking area of ​​the overlapping gate line 122 and the wet weight of the ink during printing.

[0116] It should be noted that since the overlapping grid line 122 extends along the first direction X1, the dimension of the overlapping grid line 122 in the first direction X1 is the length, and the dimension of the overlapping grid line 122 in the second direction Y1 is the width.

[0117] In this application, when solar cells are interconnected, the lap grid lines need to be alloyed with conductive wires. The alloying process includes, for example, welding or heat alloying. The conductive wires are interconnecting conductive wires, such as solder ribbons, and the material of the conductive wires is, for example, tin-plated copper strips or tin-coated copper strips. After alloying, current is transferred between the lap grid lines and the conductive wires to interconnect the solar cells. Because the conductive wires are prone to causing a silver-etching reaction with the electrode material (e.g., silver) of the lap grid lines during the alloying process—a "silver-etching reaction"—meaning that the tin-based alloy on the surface of the conductive wires reacts with the silver in the electrode material to be soldered, thereby reducing the silver content in the electrode material. Therefore, the lap grid lines must not only be resistant to grid breakage during alloying with the conductive wires but also possess low shading area. For this reason, the lap grid lines in this application have various structural forms.

[0118] See Figure 7 In one example of (A), the overlapping grid line 122 is rectangular. That is, the width of the overlapping grid line 122 is the same at all points along the first direction X1. This uniformly wide overlapping grid line 122 can make good contact with the conductive wire at all points. Moreover, the rectangular overlapping grid line 122 has equal width at all points, resulting in good ink filling effect during printing, better printing quality, and fewer printing abnormalities such as false printing.

[0119] See Figure 7 In another example (B), along the first direction X1, the overlapping grid line 122 includes an overlapping section 1221 located in the middle, and a narrowing section 1222 extending from the opposite end of the overlapping section 1221 in a direction away from the overlapping section 1221. The width of the narrowing section 1222 in the second direction Y1 narrows in a direction away from the overlapping section 1221, and the maximum width of the narrowing section 1222 in the second direction Y1 is less than or equal to the width of the overlapping section 1221.

[0120] In this example, since the conductive wire is aligned with the overlapping section 1221, the probability of the conductive wire contacting the overlapping section 1221 is relatively high. When the conductive wire contacts the overlapping section 1221, the widest point of the overlapping grid line 122 is located on the overlapping section 1221, indicating that the overlapping section 1221 uses more paste for printing. The overlapping section 1221 contains more electrode material to better block the silver etching reaction caused by the conductive wire, thereby reducing the risk of grid line 122 breaking. The narrowing section 1222 has a lower probability of contacting the conductive wire. The narrowing section 1222 is beneficial to reduce the overall light-blocking area of ​​the overlapping grid line 122 and the wet weight of the paste during printing.

[0121] See Figure 7In another example (C), along the first direction X1, the overlapping grid line 122 includes an overlapping section 1221 located in the middle, a narrowing section 1222 extending from the opposite end of the overlapping section 1221 away from the overlapping section 1221, and a connecting section 1223 connected to the end of the narrowing section 1222 away from the overlapping section 1221. The width of the narrowing section 1222 in the second direction Y1 narrows in the direction away from the overlapping section 1221, the maximum width of the narrowing section 1222 in the second direction Y1 is less than or equal to the width of the overlapping section 1221, and the width of the connecting section 1223 in the second direction Y1 is equal to the width at the narrowest point of the narrowing section 122.

[0122] In this example, since the conductive wire is aligned with the overlapping section 1221, the probability of the conductive wire contacting the overlapping section 1221 is relatively high. When the conductive wire contacts the overlapping section 1221, the widest point of the overlapping grid line 122 is located on the overlapping section 1221, indicating that the overlapping section 1221 uses more paste for printing. The overlapping section 1221 contains more electrode material to better block the silver etching reaction caused by the conductive wire, thereby reducing the risk of grid line 122 breaking. The narrowing section 1222 has a lower probability of contacting the conductive wire. The narrowing section 1222 is beneficial to reduce the overall light-blocking area of ​​the overlapping grid line 122 and the wet weight of the paste during printing. The connecting section 1223 can shorten the length of the overlapping section 1221 and the narrowing section 1222. Since the width of the overlapping section 1221 and the narrowing section 1222 is generally wider than that of the connecting section 1223, when the length of the overlapping section 1221 and the narrowing section 1222 is short, the overall light-blocking area of ​​the overlapping grid line 122 and the wet weight of the paste during printing can be further reduced.

[0123] More specifically, the overlapping segment 1221 and connecting segment 1223 in the above example can be square. The narrowing segment 1222 can be trapezoidal, that is, the narrowing segment 1222 gradually narrows.

[0124] Secondly, see the return. Figure 2 and Figure 3 This application discloses a solar cell 10, including a cell body 14 and an electrode structure 11 as described in the first aspect. The electrode structure 11 is disposed on the surface of the cell body 14.

[0125] The beneficial effects of the solar cell 10 of this application will be explained below.

[0126] By optimizing the pattern of the collector grid lines 13, the electrode structure 11 can utilize a high aperture ratio printing screen to print narrower linewidth collector grid lines 13, which is beneficial for cost reduction and efficiency improvement of the solar cell 10. Furthermore, the high aperture ratio printing screen has strong structural strength and a long service life. In addition, the electrode structure 11 intersects two discontinuous collector grid lines 13 with two interconnecting grid lines 121 to collect the current from these two collector grid lines 13 to the overlapping grid line 122. The interconnecting grid lines 121 extend along the second direction Y1, ensuring that even if the collector grid lines 13 are printed off-center in the second direction Y1, they can still intersect with the interconnecting grid lines 121, achieving current convergence and improving current transmission efficiency, thereby enhancing the conversion efficiency of the solar cell 10.

[0127] The battery body in this application will be described in detail below.

[0128] In some embodiments, such as Figure 8 to Figure 10 As shown, the battery body 14 includes a silicon substrate 141, a doped layer 142, and a first functional film 143. The doped layer 142 and the first functional film 143 are sequentially stacked on the silicon substrate 141 in a direction away from the silicon substrate 141. Interconnect gate lines 121 and overlapping gate lines 122 are disposed on the side of the first functional film 143 away from the silicon substrate 141. The current collector gate line 13 penetrates the first functional film 143 and makes ohmic contact with the doped layer 142.

[0129] Understandably, since interconnect gate 121 and overlapping gate 122 need to conduct current flow, the current intensity is relatively high when they converge. To reduce current transmission losses, interconnect gate 121 and overlapping gate 122 need to have low resistivity. Therefore, interconnect gate 121 and overlapping gate 122 are both relatively wide, so that their cross-sectional area is large enough to reduce resistivity. Interconnect gate 121 and overlapping gate 122 can be printed together with non-burn-through paste. The wider interconnect gate 121 and overlapping gate 122 do not penetrate the first functional film 143, which can reduce the damage of electrode structure 11 to the first functional film 143, thereby reducing the impact on the performance of the first functional film 143. Since the interconnecting gate line 121 and the overlapping gate line 122 are printed together, there is no need to consider printing mating between them, so as to ensure the conductivity between the interconnecting gate line 121 and the overlapping gate line 122.

[0130] The collector grid line 13 requires a burn-through paste to penetrate the first functional film 143 and make ohmic contact with the doped layer 142, thereby collecting the current within the doped layer 142. Because the collector grid line 13 is narrow, damage to the first functional film 143 can be reduced, thus minimizing the impact on the performance of the first functional film 143.

[0131] Of course, interconnect gate lines and / or overlapping gate lines can also penetrate the first functional film and make ohmic contact with the doped layer.

[0132] More specifically, the silicon substrate 141 can be an N-type silicon substrate or a P-type silicon substrate. The doped layer 142 can be a diffusion layer, such as an N-type diffusion layer or a P-type diffusion layer. The doped layer 142 can also be an N-type doped polysilicon layer or a P-type doped polysilicon layer. The first functional film 143 can be a passivation film and / or an antireflection film. The material of the first functional film 143 can be silicon nitride, silicon oxynitride, silicon oxide, or aluminum oxide.

[0133] For example, the solar cell 10 can be a passivated contact solar cell, and the doped layer 142 and the first functional film 143 can be disposed on the light-receiving surface and / or the back-lighting surface of the silicon substrate 141. In other words, the electrode structure 11 can be disposed on the light-receiving surface and / or the back-lighting surface of the silicon substrate 141. When the doped layer 142 and the first functional film 143 are disposed on the light-receiving surface of the silicon substrate 141, the cell body 14 further includes an interface passivation layer 144, a doped polycrystalline silicon layer 145, and a second functional film 146. The interface passivation layer 144, the doped polycrystalline silicon layer 145, and the second functional film 146 are sequentially stacked on the back-lighting surface of the silicon substrate 141 in a direction away from the silicon substrate 141.

[0134] More specifically, the material of the interface passivation layer 144 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. The second functional film 146 can be a passivation film and / or an antireflection film. The material of the second functional film 146 can be silicon nitride, silicon oxynitride, silicon oxide, or aluminum oxide.

[0135] Of course, the type of solar cell can also be a heterojunction solar cell or a back contact solar cell.

[0136] Thirdly, see Figure 11 and Figure 12 This application discloses a printing screen assembly, including a first printing screen 20 and a second printing screen 30.

[0137] The first printing screen 20 is provided with printing groove structures 21. Each printing groove structure 21 includes two spaced-apart interconnecting grid printing grooves 211 and overlapping grid printing grooves 212 connecting the two interconnecting grid printing grooves 211. The two interconnecting grid printing grooves 211 are spaced apart in a third direction X2, and the distance between the two interconnecting grid printing grooves 211 in the third direction X2 is D3. The extension direction of the interconnecting grid printing grooves 211 is a fourth direction Y2, and the third direction X2 intersects with the fourth direction Y2.

[0138] The second printing screen 30 has multiple collector line printing slots 31, at least one of which has an opening ratio of 90% to 100%. The multiple collector line printing slots 31 are spaced apart along the fifth direction X3 and extend along the fifth direction X3. Two adjacent collector line printing slots 31 in the fifth direction X3 form a pair, and the distance between the two collector line printing slots 31 in the same pair in the fifth direction X3 is D4. Where D4 ≤ D3.

[0139] It should be noted that the printing screen assembly is used to print the electrode structure described in the first aspect. Specifically, the printing groove structure 21 of the first printing screen 20 is configured to print a busbar structure on the battery body. The interconnect grid printing groove 211 is configured to print interconnect grid lines on the battery body, and each overlapping grid printing groove 212 is configured to print overlapping grid lines on the battery body. The current collector grid printing grooves 31 of the second printing screen 30 are configured to print current collector grid printing grooves 31 on the battery body.

[0140] The beneficial effects of the printing screen component of this application will be described in detail below.

[0141] In this printing screen assembly, the second printing screen 30, through the high-aperture-ratio collector grid printing grooves 31, can print narrower and better-shaped collector grid lines, which is beneficial for cost reduction and efficiency improvement of solar cells. Furthermore, the collector grid printing grooves 31 are intermittently divided into multiple lines in the fifth direction X3, and each collector grid printing groove 31 is relatively short, giving the second printing screen 30 higher structural strength and a longer service life.

[0142] Building upon this, in order to collect current from multiple discontinuous collector grid lines, this application further prints a busbar structure through the printing groove structure 21 of the first printing screen 20, enabling a pair of discontinuous collector grid lines to collect current to the overlapping grid lines through two interconnecting grid lines. The interconnecting grid line printing groove 211 also provides a margin for printing offset of the second printing screen 30, which is beneficial to improving the overall printing yield of the electrode structure.

[0143] Specifically, the aperture ratio of the current collector grid printing groove 31 in this application is 90% to 100%, including any value within this range, such as 90%, 95%, or 100%. It is understood that a higher aperture ratio indicates fewer solid structures in the current collector grid printing groove 31, resulting in less paste obstruction caused by these structures, better paste flow, and the ability to print narrower current collector grid lines with fewer morphological defects. In this application, the aforementioned paste refers to the grid printing paste for solar cells, such as silver paste, aluminum paste, silver-coated copper paste, or silver-aluminum paste.

[0144] In other words, the current collector grid printing groove 31 of this application 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.

[0145] However, the longer the printed groove 31 with a high aperture ratio, the lower the structural strength of the second printing screen 30. To shorten the length of the printed groove 31, the printed groove 31 in this embodiment is intermittently arranged. Specifically, multiple printed grooves 31 are spaced apart along the fifth direction X3. Two adjacent printed grooves 31 in the fifth direction X3 form a pair, and this pair of printed grooves 31 prints a pair of intermittent, shorter printed grooves. As analyzed in the first aspect, the current collection range of a pair of printed grooves is equivalent to the distance between the two ends of this pair of printed grooves in the first direction. In other words, in order to collect current from the surface of a battery body of a certain size, related technologies use a single continuous, long printed groove for current collection, while the solar cell of this application can utilize multiple intermittent, shorter printed grooves combined together for current collection. Since the length of the collector grid line printing groove 31 is the same as the length of the collector grid line, in other words, the length of the discontinuous collector grid line printing groove 31 in this application is also shorter, which makes the structure of the second printing screen 30 stronger and its service life longer.

[0146] Moreover, the current collector line printing groove 31 is relatively short in length. When the squeegee applies force on the first printing screen 20, the deformation of the current collector line printing groove 31 is small, thereby reducing the printing offset and excessively thick grid lines caused by the deformation of the current collector line printing groove 31.

[0147] Based on this, in order to collect the current of a pair of discontinuous collector grid lines, this application utilizes the printing groove structure 21 of the first printing screen 20 to print a busbar structure on the battery body. Each printing groove structure 21 includes two spaced interconnect grid line printing grooves 211 and an overlapping grid line printing groove 212 connecting the two interconnect grid line printing grooves 211. Since the distance D3 between the two interconnect grid line printing grooves 211 in the third direction X2 and the distance D4 between the two collector grid line printing grooves 31 in the same pair in the fifth direction X3 have the following relationship: D4≤D3, the spacing between the two interconnect grid lines printed by the two interconnect grid line printing grooves 211 will be less than or equal to the spacing between the two collector grid lines in the same pair. This allows the two collector grid lines to intersect the two interconnect grid lines respectively, enabling the current of these two collector grid lines to be collected through the interconnect grid lines to the overlapping grid line.

[0148] Furthermore, the extension direction of the interconnect grid lines printed in the interconnect grid printing groove 211 can be configured to intersect with the extension direction of the collector grid lines. This ensures that even if the collector grid printing groove 31 experiences a certain degree of offset during printing, the resulting collector grid lines will still intersect with the interconnect grid lines. In other words, the graphic design of the first printing screen 20 also provides a margin for printing offset of the second printing screen 30, which is beneficial for improving the printing yield of the printing screen assembly.

[0149] 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 can print the busbar structure first, and then the second printing screen 30 can print the collector lines. Or, for another example, the second printing screen 30 can print the collector lines first, and then the first printing screen 20 can print the busbar structure.

[0150] In some embodiments, see Figure 11 and Figure 12 Multiple pairs of collector grid line printing grooves 31 are arranged in two columns at intervals along the sixth direction Y3. Each column of collector grid line printing grooves 31 includes multiple collector grid line printing grooves 31 arranged at intervals along the sixth direction Y3. The sixth direction Y3 intersects with the fifth direction X3.

[0151] Each column of collector grid lines is printed in a printing groove 31, so that multiple collector grid lines are arranged in a row to be distributed on the surface of the solar cell, thereby better collecting the current on the surface of the solar cell.

[0152] Optionally, the fifth direction X3 and the sixth direction Y3 are perpendicular. Of course, the sixth direction Y3 and the fifth direction X3 can also be slightly deviated from 90°, such as 80°, 85°, 89°, etc., and this application embodiment does not limit this.

[0153] It should be noted that the number of columns of the current collector line printing grooves 31 is not limited to two columns, but can also be three, four, five, or other numbers, and this application embodiment does not limit this. Furthermore, the multiple columns of current collector line printing grooves 31 are arranged at intervals along the fifth direction X3.

[0154] Based on this, in each printing slot structure 21, there are multiple overlapping grid line printing slots 212, which are spaced apart along the fourth direction Y2. Each printing slot structure 21 prints a bus structure between two columns of collector grid lines, and each bus structure collects current from the two columns of collector grid lines to enhance the current collection effect of the bus structure.

[0155] Furthermore, there are multiple printing groove structures 21, which are spaced apart along the third direction X2. The distance between two adjacent printing groove structures 21 in the third direction X2 is D5.

[0156] At least three rows of collector grid line printing grooves 31 are arranged at intervals along the fifth direction X3, and at least one row of collector grid line printing grooves 31 has a dimension of D6 in the fifth direction X3. Wherein, D5 < D6.

[0157] The overlapping grid line printing groove 212 in this application will be described in detail below.

[0158] In some embodiments, referencing the back Figure 11 The overlapping grid line printing groove 212 extends along the third direction X2. The two ends of the overlapping grid line printing groove 212 on the third direction X2 are connected to two interconnecting grid line printing grooves 211 respectively. The third direction X2 is perpendicular to the fourth direction Y2.

[0159] As analyzed in the first aspect, in short, the overlapping grid lines printed in the overlapping grid line printing groove 212 must not only be less prone to breakage when alloyed with the conductive wire, but also have characteristics such as low wet weight of the paste during printing. Therefore, the overlapping grid line printing groove 212 of this application has various structural forms, as detailed below.

[0160] like Figure 13 As shown in (A), in one example, the overlapping grid line printing groove 212 is rectangular. In this example, the width of the overlapping grid line printing groove 212 is consistent throughout, which ensures consistent ink flow throughout the overlapping grid line printing groove 212 and helps reduce the phenomenon of incomplete printing of the overlapping grid lines.

[0161] like Figure 13 As shown in (B), in another example, along the third direction X2, the overlapping grid line printing groove 212 includes an overlapping section printing portion 2121 located in the middle, and a narrowing section printing portion 2122 extending from the opposite end of the overlapping section printing portion 2121 in a direction away from the overlapping section printing portion 2121; the width of the narrowing section printing portion 2122 in the fourth direction Y2 narrows in a direction away from the overlapping section printing portion 2121, and the maximum width of the narrowing section printing portion 2122 in the fourth direction Y2 is less than or equal to the width of the overlapping section printing portion 2121.

[0162] In this example, the widest point of the overlap grid line printing groove 212 is located on the overlap section printing section 2121. The wider overlap section printing section 2121 results in a wider overlap section. The overlap section is alloyed with the conductive wire to better block the silver etching reaction of the conductive wire and reduce the risk of grid line breakage. The narrowing section printing section 2122 is narrowed to reduce the wet weight of the paste during the printing of the overlap grid line.

[0163] like Figure 13As shown in (C), in another example, along the third direction X2, the overlapping grid line printing groove 212 includes an overlapping section printing portion 2121 located in the middle, a narrowing section printing portion 2122 extending from the opposite end of the overlapping section printing portion 2121 in a direction away from the overlapping section printing portion 2121, and a connecting section printing portion 2123 connected to the end of the narrowing section printing portion 2122 away from the overlapping section printing portion 2121; the width of the narrowing section printing portion 2122 in the fourth direction Y2 narrows in a direction away from the overlapping section printing portion 2121, the maximum width of the narrowing section printing portion 2122 in the fourth direction Y2 is less than or equal to the width of the overlapping section printing portion 2121, and the width of the connecting section printing portion 2123 in the fourth direction Y2 is equal to the width at the narrowest point of the narrowing section printing portion 2122.

[0164] In this example, the widest point of the overlapping grid line printing groove 212 is located on the overlapping section printing portion 2121. The wider overlapping section printing portion 2121 results in a wider overlapping section. The overlapping section is alloyed with the conductive wire to better block the silver etching reaction of the conductive wire, reducing the risk of grid line breakage. The narrowing section printing portion 2122 is narrowed to reduce the wet weight of the paste during the printing of the overlapping grid line. The connecting section printing portion 2123 can shorten the length of the overlapping section printing portion 2121 and the narrowing section printing portion 2122. Since the overall width of the overlapping section printing portion 2121 and the narrowing section printing portion 2122 is relatively wide, when the length of the overlapping section printing portion 2121 and the narrowing section printing portion 2122 is shortened, the overall area of ​​the overlapping grid line printing groove 212 becomes smaller, and the wet weight of the paste during printing is lower, which helps to reduce the manufacturing cost of solar cells.

[0165] 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, at least one of the solar cells being printed by a printing screen assembly as described in the third aspect.

[0166] 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: A busbar structure includes two spaced interconnect gate lines and an overlapping gate line connecting the two interconnect gate lines. The two interconnect gate lines are spaced in a first direction, and the extension direction of the interconnect gate lines is a second direction. The first direction and the second direction intersect. as well as Multiple collector grid lines are spaced apart along the first direction and extend along the first direction. Two adjacent collector grid lines in the first direction form a pair. In at least one pair of collector grid lines, the ends of the two collector grid lines closest to each other intersect with two interconnect grid lines in the same busbar structure.

2. The electrode structure according to claim 1, characterized in that, The number of the bus substructures is multiple, and the number of the overlapping grid lines in each bus substructure is multiple, with the multiple overlapping grid lines spaced apart along the second direction; Multiple pairs of collector grid lines are spaced apart in two columns along the second direction, and each column of collector grid lines includes multiple collector grid lines spaced apart in the second direction; in the first direction, the ends of the two columns of collector grid lines close to each other intersect with two interconnect grid lines in the same busbar structure, so that the two columns of collector grid lines are connected to the same busbar structure.

3. The electrode structure according to claim 2, characterized in that, In at least one of the said bus substructures, a plurality of said overlapping grid lines are equidistantly arranged along the second direction; And / or, in at least one column, a plurality of said collector grid lines are equidistantly arranged along the second direction; And / or, in each of the busbar structures, the spacing between two adjacent overlapping grid lines in the second direction is D1; ​​in the same column, the spacing between two adjacent collector grid lines is D2; wherein, D1 / D2 = 0.3 to 3.

4. The electrode structure according to claim 2, characterized in that, The plurality of said busbar structures are spaced apart along the first direction; At least three columns of the collector grid lines are spaced apart along the first direction, the Nth and N+1th columns of the collector grid lines are connected to the Nth bus structure, and the N+1th and N+2th columns of the collector grid lines are connected to the N+1th bus structure; where N is a positive integer.

5. The electrode structure according to claim 1, characterized in that, The overlapping grid line extends along the first direction, and the two ends of the overlapping grid line in the first direction are respectively connected to the two interconnecting grid lines. The first direction is perpendicular to the second direction.

6. The electrode structure according to claim 5, characterized in that, The overlapping grid line is rectangular in shape; Alternatively, along the first direction, the overlapping grid line includes an overlapping section located in the middle, and a narrowing section extending from the opposite end of the overlapping section in a direction away from the overlapping section; the width of the narrowing section in the second direction narrows in a direction away from the overlapping section, and the maximum width of the narrowing section in the second direction is less than or equal to the width of the overlapping section. Alternatively, along the first direction, the overlapping grid line includes an overlapping section located in the middle, a narrowing section extending from the opposite end of the overlapping section in a direction away from the overlapping section, and a connecting section connected to the end of the narrowing section away from the overlapping section; the width of the narrowing section in the second direction narrows in a direction away from the overlapping section, the maximum width of the narrowing section in the second direction is less than or equal to the width of the overlapping section, and the width of the connecting section in the second direction is equal to the width at the narrowest point of the narrowing section.

7. The electrode structure according to claim 1, characterized in that, In the same pair of collector gate lines, at least one of the collector gate lines passes through the intersecting interconnect gate lines along the first direction.

8. The electrode structure according to claim 7, characterized in that, The collector grid line has an extension that extends between two interconnect grid lines of the same busbar structure; In the first direction, the length of the extension segment is L1, the total length of the collector grid line is L2, and L1 / L2 = 0.1% to 10%.

9. The electrode structure according to any one of claims 1 to 8, characterized in that, The bus structure consists of two spaced-apart interconnecting gate lines and an overlapping gate line connecting the two interconnecting gate lines.

10. The electrode structure according to any one of claims 1 to 8, characterized in that, The width of the interconnect gate line in the first direction is W1, and the width of the collector gate line in the second direction is W2, where W2:W1 = 1:(1~3); And / or, the width of the interconnecting gate line in the first direction is W1, and the width of the widest part of the overlapping gate line in the second direction is W3, where W1:W3 = 1:(1~7).

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 silicon substrate in a direction away from the silicon substrate. The interconnect gate lines and the overlapping gate lines are disposed on the side of the first functional film away from the silicon substrate. The current collector gate lines penetrate 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 printing groove structures. Each printing groove structure includes two spaced-apart interconnecting grid printing grooves and an overlapping grid printing groove connecting the two interconnecting grid printing grooves. The two interconnecting grid printing grooves are spaced apart in a third direction, and the distance between the two interconnecting grid printing grooves in the third direction is D3. The extension direction of the interconnecting grid printing grooves is a fourth direction, and the third direction intersects with the fourth direction. as well as The second printing screen has multiple collector grid printing slots, at least one of which has an opening ratio of 90% to 100%. The multiple collector grid printing slots are spaced apart along a fifth direction and extend along the fifth direction. Two adjacent collector grid printing slots in the fifth direction form a pair, and the distance between the two collector grid printing slots in the same pair in the fifth direction is D4; wherein, D4≤D3.

14. The printing screen assembly according to claim 13, characterized in that, In each of the aforementioned printing groove structures, there are multiple overlapping grid line printing grooves, and the multiple overlapping grid line printing grooves are spaced apart along the fourth direction; Multiple pairs of the current collector wire printing grooves are arranged in two columns at intervals along the sixth direction. Each column of the current collector wire printing grooves includes multiple current collector wire printing grooves arranged at intervals along the sixth direction, and the sixth direction intersects with the fifth direction.

15. The printing screen assembly according to claim 14, characterized in that, The number of printing groove structures is multiple, and the multiple printing groove structures are spaced apart along the third direction; the distance between two adjacent printing groove structures in the third direction is D5; At least three columns of the current collector wire printing grooves are spaced apart along the fifth direction, and at least one column of the current collector wire printing grooves has a dimension of D6 in the fifth direction; wherein, D5 < D6.

16. The printing screen assembly according to any one of claims 13 to 15, characterized in that, The overlapping grid line printing groove extends along the third direction, and the two ends of the overlapping grid line printing groove in the third direction are connected to the two interconnecting grid line printing grooves respectively. The third direction is perpendicular to the fourth direction.

17. The printing screen assembly according to claim 16, characterized in that, The graphic of the overlapping grid line printing groove is rectangular; Alternatively, along the third direction upward, the overlapping grid line printing groove includes an overlapping section printing portion located in the middle, and a narrowing section printing portion extending from the opposite end of the overlapping section printing portion in a direction away from the overlapping section printing portion; the width of the narrowing section printing portion in the fourth direction narrows in a direction away from the overlapping section printing portion, and the maximum width of the narrowing section printing portion in the fourth direction is less than or equal to the width of the overlapping section printing portion. Alternatively, along the third direction upwards, the overlapping grid line printing groove includes an overlapping section printing portion located in the middle, a narrowing section printing portion extending from the opposite end of the overlapping section printing portion in a direction away from the overlapping section printing portion, and a connecting section printing portion connected to the end of the narrowing section printing portion away from the overlapping section printing portion; the width of the narrowing section printing portion in the fourth direction narrows in a direction away from the overlapping section printing portion, the maximum width of the narrowing section printing portion in the fourth direction is less than or equal to the width of the overlapping section printing portion, and the width of the connecting section printing portion in the fourth direction is equal to the width at the narrowest point of the narrowing section printing portion.

18. A photovoltaic module, characterized in that, The solar cell comprises a plurality of electrically connected solar cells, at least one of the solar cells having 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, at least one of the solar cells is obtained by printing using a screen printing assembly as described in any one of claims 13 to 17.

Images