Method for manufacturing solar cell grid lines, solar cell and module

Abstract

The application relates to the technical field of solar cells, in particular to a preparation method of a solar cell grid line, a solar cell and a battery assembly. The preparation method of the solar cell grid line comprises the following steps: setting a first printing parameter, the first printing parameter is configured to make the grid line formed by printing reach a first preset state; performing first printing by using the first printing parameter to form a first grid line; setting a second printing parameter according to a preset rule, and performing more than one printing by using the second printing parameter; the preset rule comprises that the wave crest of the grid line formed by printing by using the second printing parameter is coincided with the wave trough of the first grid line. The preparation method of the solar cell grid line provided by the application improves the height-width ratio and height uniformity of the grid line.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to methods for fabricating solar cell grid lines, solar cells, and cell modules. Background Technology

[0002] The photovoltaic cell industry commonly uses screen printing technology to print grid lines on solar cells. However, due to limitations such as conductive paste and screen parameters, the grid lines produced by traditional single-pass printing processes usually have a low aspect ratio, and the printed grid lines are affected by the screen and exhibit unevenness.

[0003] To improve the aspect ratio and morphology of the grid lines, the industry has proposed a double-printing overprinting technique. While this technique improves the grid line height to some extent, it has the following problems: 1) It usually requires additional printing presses, drying ovens, and vision alignment equipment, which greatly increases production costs; 2) Some double-printing overprinting techniques use two independent screens. Due to slight differences in parameters such as line width and tension between the two screens, as well as limitations in alignment accuracy, it is very easy to cause severe widening and burrs in the final grid lines, resulting in unstable overprinting effects. Summary of the Invention

[0004] Based on this, the main objective of this application is to provide a method for fabricating solar cell grid lines, which improves the aspect ratio and high uniformity of the grid lines.

[0005] The first aspect of this application provides a method for fabricating a solar cell grid line, comprising the following steps:

[0006] Set a first printing parameter, which is configured to make the printed grid lines reach a first preset state;

[0007] The first printing is performed using the first printing parameters to form the first grid line;

[0008] Set the second printing parameters according to the preset rules, and perform printing more than once using the second printing parameters;

[0009] The preset rules include: the peaks of the grid lines formed by printing with the second printing parameters coincide with the troughs of the first grid lines.

[0010] In some embodiments, the first printing parameter or the second printing parameter includes paste parameters and screen parameters. In some embodiments, the step of setting the first printing parameter includes:

[0011] Set the basic printing parameters according to the parameters of the paste and screen used;

[0012] Perform a trial print using the basic printing parameters to determine whether the grid lines formed by the trial print meet the first preset state.

[0013] If so, set the basic printing parameters as the first printing parameters;

[0014] If not, adjust the basic printing parameters and perform a trial print until the grid lines reach the first preset state, and then determine the adjusted basic printing parameters as the first printing parameters.

[0015] In some implementations, after the step of setting the second printing parameters according to preset rules, the method further includes: performing a trial print with the second printing parameters and determining whether the grid lines formed by the trial print meet the second preset state.

[0016] If so, print more than once using the second printing parameters;

[0017] If not, adjust the second printing parameters and perform a trial print until the grid lines reach the second preset state, then perform one or more prints using the adjusted second printing parameters.

[0018] The second preset state refers to: under microscope observation, no burrs appear on the grid lines; the average linewidth of the grid lines is less than 125% of the average linewidth of the first grid lines; and the relative standard deviation of the grid line height is less than 5%.

[0019] In some implementations, the basic printing parameters and the second printing parameters each independently include screen spacing, printing speed, and printing pressure.

[0020] In some implementations, the basic printing parameters are: screen spacing of 1.4mm to 1.7mm, printing speed of 300mm / s to 450mm / s, and printing pressure of 40N to 60N.

[0021] In some implementations, the printing screen used is a meshless screen printing screen.

[0022] In some implementations, the aspect ratio of the solar cell grid lines is 40% or higher.

[0023] The second aspect of this application provides a solar cell, including solar cell grid lines prepared using the method for preparing solar cell grid lines provided in the first aspect of this application.

[0024] A third aspect of this application provides a battery assembly including the solar cell provided in the second aspect of this application.

[0025] Compared with traditional technologies, this application has the following advantages:

[0026] This application achieves multiple printings using the same screen, eliminating the need for the solar cells to leave the screen. This avoids alignment errors and screen wear caused by multiple cell positioning, improving alignment accuracy and batch consistency across multiple printings. Simultaneously, by adjusting the printing parameters between the first and subsequent prints, the peaks of the grid lines formed by subsequent prints coincide with the troughs of the first grid line. Through the overlapping and filling effect of the paste from secondary or multiple prints, the grid line height becomes smoother, ultimately forming smooth grid lines with uniform height and an approximately triangular cross-section, thus improving the aspect ratio and height uniformity of the grid lines. Attached Figure Description

[0027] To better describe and illustrate embodiments or examples of the applications disclosed herein, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the embodiments or examples currently described, or the best mode of conduct of these applications as currently understood. Furthermore, throughout the drawings, the same reference numerals denote the same parts.

[0028] Figure 1 This is a schematic diagram of the structure for forming grid lines using conventional two-stage printing overprinting technology.

[0029] Figure 2 This is a schematic diagram of a method for fabricating solar cell grid lines according to an embodiment of this application.

[0030] Figure 3a and Figure 3b Each image is an independent scanning electron microscope image of the grid line when it reaches the first preset state.

[0031] Figure 4 This is a schematic diagram of the structure of the first grid line in one embodiment of this application.

[0032] Figure 5 This is a schematic diagram of the structure for forming grid lines by the second printing in one embodiment of this application.

[0033] Figure 6 This is a schematic diagram of the structure of the third printing forming the grid lines in one embodiment of this application.

[0034] Figure 7 This is a scanning electron microscope image of the first printing of the grid lines in Embodiment 1 of this application.

[0035] Figure 8 This is a scanning electron microscope image of the grid lines formed by the second printing in Embodiment 1 of this application.

[0036] Figure 9 This is a scanning electron microscope image of the grid lines formed by the third printing in Embodiment 1 of this application.

[0037] Figure 10This is a scanning electron microscope image of the first printing of the grid lines in Embodiment 2 of this application.

[0038] Figure 11 This is a scanning electron microscope image of the grid lines formed by the second printing in Embodiment 2 of this application. Detailed Implementation

[0039] A detailed reference is now provided to embodiments of this application, one or more of which are described below. Each embodiment is provided for explanation and not for limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0040] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0" and "5" have been listed in this document; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, stating that a parameter is an integer ≥ 2 is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, stating that a parameter is an integer selected from "2-10" is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0041] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0042] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0043] Unless otherwise specified, the terms "comprising," "containing," and "including" as used in this application can be open-ended or closed-ended. In open-ended cases, for example, "comprising," "containing," and "including" can mean that other members, elements, or method steps not listed can also be included, or that only the listed members, elements, or method steps can be included.

[0044] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0045] In this application, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0046] The applicant discovered that some secondary printing overprinting techniques, although using the same screen (e.g., printing and drying first followed by a second printing in the same direction, or replacing the return blade with a reverse squeegee, and then performing a second printing during the return stroke), while avoiding line width deviations caused by screen changes and thus helping to control line width consistency, still exhibit unevenness on the screen (e.g., ...). Figure 1 (As shown).

[0047] Based on this, such as Figure 2 As shown, the first aspect of this application provides a method for fabricating a solar cell grid line, comprising the following steps:

[0048] S1. Set the first printing parameters. The first printing parameters are configured to make the printed grid lines reach a first preset state.

[0049] S2. Perform the first printing with the first printing parameters to form the first grid line.

[0050] S3. Set the second printing parameters according to the preset rules, and perform printing once or more using the second printing parameters.

[0051] The preset rules include: the peaks of the grid lines formed by printing with the second printing parameters coincide with the troughs of the first grid lines.

[0052] It should be noted that the "first preset state" in S1 refers to the state where, after the grid lines are printed, they appear as continuous lines under visual inspection, but under a microscope, the grid lines show local thinning or narrowing, indicating a critical state of imminent breakage, or a state where some areas are already broken; this can also be called a "virtual printing state." For example, such as... Figure 3a and Figure 3b The images shown are independent scanning electron microscope (SEM) images of the grid lines when they reach the "first preset state". Figure 3a and Figure 3b The text has already used elliptical frames to mark individual areas where the grid lines become thinner or narrower.

[0053] Along the length of the grid lines, the height of the grid lines exhibits a microscopic undulating shape. Local high points where the height value on the grid line is higher than that of adjacent areas or the average height of the grid lines are called "peaks," and local low points where the height value on the grid line is lower than that of adjacent areas or the average height of the grid lines are called "valleys." In this application's embodiments, peaks and valleys are assumed to be formed by printing on substrates with the same roughness or flatness. This application does not particularly limit the specific model of the microscope (e.g., a 3D microscope, metallurgical microscope). Provided that the overall inventive concept of this application is satisfied, any known microscope can be used in this application. The following are merely examples: microscopes such as Olympus 3D microscopes, Zeta 3D microscopes, Minolta 3D microscopes, or scanning electron microscopes (SEMs).

[0054] This application reduces the line width and wet weight of the first print by setting the first printing parameters in step S1, thereby avoiding the formation of rough edges due to the pressing of the paste during subsequent printing and improving the printing quality.

[0055] This application achieves multiple printings using the same screen, eliminating the need for the solar cells to leave the screen. This avoids alignment errors and screen wear caused by multiple cell positioning, improving alignment accuracy and batch consistency across multiple printings. Simultaneously, by adjusting the printing parameters between the first and subsequent prints, the peaks of the grid lines formed by subsequent prints coincide with the troughs of the first grid line. Through the overlapping and filling effect of the paste from secondary or multiple prints, the grid line height becomes smoother, ultimately forming smooth grid lines with uniform height and an approximately triangular cross-section, thus improving the aspect ratio and height uniformity of the grid lines.

[0056] In this application, "triangle" refers to an isosceles triangle shape with an acute angle in the cross-section of the grid lines printed using paste.

[0057] In some implementations, the first or second printing parameters include paste parameters and screen parameters.

[0058] In some implementations, the slurry parameters include the type and viscosity of the slurry; the screen parameters include the screen opening, screen yarn thickness, screen mesh count, screen wire diameter, screen opening angle, and screen tension.

[0059] In this application, "screen opening" refers to the width of the opening of the screen grid lines.

[0060] It is understandable that a screen printing apparatus is used for paste printing. A screen printing apparatus includes at least a screen, a squeegee, a feed knife, and a printing platform. The preparation steps before printing include: installing the screen, squeegee, and feed knife; placing the sample to be printed (e.g., a solar cell) on the printing platform; and laying the paste on the screen.

[0061] In some implementations, the step of setting the first printing parameters includes:

[0062] S10. Set the basic printing parameters according to the parameters of the paste and screen used.

[0063] S11. Perform trial printing using the basic printing parameters and determine whether the grid lines formed by the trial printing meet the first preset state. If yes, determine the basic printing parameters as the first printing parameters. If no, adjust the basic printing parameters and perform trial printing until the grid lines reach the first preset state, and determine the adjusted printing parameters as the first printing parameters.

[0064] In some implementations, the basic printing parameters and the second printing parameters each independently include screen spacing, printing speed, and printing pressure.

[0065] In some implementations, basic printing parameters include screen spacing, printing speed, and printing pressure.

[0066] In this application, "screen spacing" refers to the distance between the upper surface of the battery cell and the lower surface of the screen during printing.

[0067] In this application, "squeegee pressure" refers to the set value of the squeegee pressure distance during printing.

[0068] For example, in S11 above, the adjustment of the basic printing parameters can be to adjust the printing speed or to adjust the squeegee pressure.

[0069] Taking printing speed control as an example, when the printing speed S2 of the second printing parameter and the printing speed S1 of the first printing parameter satisfy the following relationship: S2 = |S1 + n × ΔS|, the optimal peak-valley complementary effect can be achieved. In the formula, S1 is the printing speed in the first printing parameter; S2 is the printing speed in the second or subsequent printing parameters; n is a non-zero integer; and ΔS is the effective speed change. ΔS is related to the printing system, specifically to the paste parameters, screen parameters, and printing parameters of the specific printing system. By changing the system parameters of subsequent secondary or multiple printings to alter the phase of the paste flow field, the peaks of the grid lines formed by the second or subsequent printings fill the troughs of the grid lines formed by the first printing, thus resulting in a smooth grid line height.

[0070] 200mm / s ≤ |S2| ≤ 800mm / s. When S2 is positive, subsequent prints (or prints after the first print) are in the same direction as the first print. When S2 is negative, subsequent prints are in the opposite direction to the first print. In other words, the printing direction is relative to the first print; the same direction is positive, and the opposite direction is negative.

[0071] △S is an inherent property of a specific printing system and can be obtained through experimental calibration, including the following steps:

[0072] S100, fixed first printing speed S1, and all other system parameters.

[0073] S200, near S1, a series of second printing experiments were conducted with different speed differences.

[0074] S300. Using a microscope, quantitatively evaluate the height uniformity and aspect ratio of the grid lines in each experiment.

[0075] S400. The speed difference corresponding to the optimal evaluation result is determined as the ΔS value of this specific printing system.

[0076] In some embodiments, after the step of setting the second printing parameters according to preset rules, the following steps are also included: performing trial printing with the second printing parameters, and determining whether the grid lines formed by the trial printing meet the second preset state; if yes, performing printing once or more with the second printing parameters; if no, adjusting the second printing parameters and performing trial printing until the grid lines reach the second preset state, and then performing printing once or more with the adjusted second printing parameters.

[0077] The second preset state refers to the following: under a microscope, the printed grid lines do not show any burrs; the average line width of the grid lines is less than 125% of the average line width of the first grid lines; and the relative standard deviation of the grid line height is less than 5%.

[0078] In some implementations, the basic printing parameters satisfy: the screen spacing is 1.4mm to 1.7mm, for example 1.4mm, 1.5mm, 1.6mm, 1.7mm, and any value within the range of any two of the above values.

[0079] The printing speed for the first print is 300mm / s to 450mm / s, for example, 300mm / s, 340mm / s, 380mm / s, 400mm / s, 420mm / s, 450mm / s, and any value within the range of any two of the above values.

[0080] The printing pressure is 40N~60N, for example 40N, 45N, 50N, 55N, 60N, and any value within the range of any two of the above values.

[0081] In some embodiments, the printing screen used is a knotless screen printing screen. Using a knotless screen printing screen has two advantages: firstly, the flat surface of the screen facilitates more even transfer and leveling of the ink during multiple printing processes; secondly, it reduces local thickness fluctuations in the grid lines caused by knots, which is beneficial for this application to fill the first grid line troughs and obtain highly uniform grid lines through multiple printing processes.

[0082] In some implementations, the aspect ratio of the solar cell grid lines is 40% or higher. Increasing the aspect ratio of the grid lines to 40% or higher allows for the creation of a higher conductive cross-section (larger line height) while maintaining a narrower shading area (smaller line width), which helps reduce shading loss on the front of the cell and improves current collection efficiency.

[0083] In this application, "aspect ratio" refers to the ratio of the gate line height to the gate line width, expressed as a percentage. Aspect ratio = (gate line height / gate line width) × 100%.

[0084] In one specific embodiment, the method for fabricating solar cell grid lines includes three printing steps: specifically, a first printing is performed on the solar cell wafer using first printing parameters to form a first grid line; then, the printing is repeated twice using a second printing parameter, and the peaks of the grid lines formed by the second printing parameters coincide with the troughs of the first grid line. Figure 4 As shown, Figure 4 This is a structural schematic diagram of the first grid line, and a cross-sectional schematic diagram along the length of the first grid line, i.e., a longitudinal cross-sectional schematic diagram of the first grid line; as shown. Figure 5 As shown, Figure 5 A schematic diagram of the structure forming the grid lines in the second printing process, a cross-sectional view along the length of the grid lines, i.e., a longitudinal cross-sectional view of the grid lines; and as shown in the diagram. Figure 6 As shown, Figure 6This is a schematic diagram of the structure of the grid lines formed by the third printing process, and a cross-sectional diagram along the length of the grid lines, i.e., a longitudinal cross-sectional diagram of the grid lines.

[0085] In some implementations, step S3 is followed by a sintering or curing process to sinter or cure the gate lines onto the silicon wafer.

[0086] The second aspect of this application provides a solar cell, including solar cell grid lines prepared using the method for preparing solar cell grid lines provided in the first aspect of this application.

[0087] A third aspect of this application provides a battery assembly including the solar cell provided in the second aspect of this application.

[0088] The present application will be further described below with reference to specific embodiments and comparative examples.

[0089] Example 1

[0090] The paste used in this embodiment is HC549-H type paste; the screen is a narrow linewidth screen with a mesh size of 520-11 (mesh count - wire diameter), an opening width of 11μm, a film thickness of 10μm, a yarn thickness of 15μm, and a tension of 16N; the squeegee angle is set to 65°, and the adhesive strip hardness is 65A; all printing steps are carried out continuously without separating the battery cell from the screen.

[0091] (1) Set the basic printing parameters: screen spacing is 1.6mm, printing speed is 400mm / s, squeegee pressure is 15.6mm, and printing pressure is 50N.

[0092] (2) Perform trial printing using the above basic printing parameters to determine whether the grid lines formed by the trial printing meet the first preset state; if yes, determine the basic printing parameters as the first printing parameters; if not, adjust the basic printing parameters and perform trial printing until the grid lines reach the first preset state, and determine the adjusted printing parameters as the first printing parameters. The adjusted first printing parameters are: screen spacing of 1.6mm, printing speed of 600mm / s, squeegee downward pressure of 15.4mm, and printing pressure of 50N.

[0093] (3) The first printing is performed using the first printing parameters mentioned above to form the first grid line.

[0094] (4) Set the second printing parameters according to the preset rules to ensure that the peak of the grid line formed by printing with the second printing parameters coincides with the trough of the first grid line. The second printing parameters are: screen spacing is 1.7mm, printing speed is 300 mm / s, squeegee pressure is 15.6mm, and printing pressure is 50N.

[0095] (5) The second and third printings are performed using the second printing parameters to form grid lines.

[0096] Each printed grid line was tested using a scanning electron microscope to measure the cross-sectional and bevel morphology of the grid line.

[0097] like Figure 7 As shown, Figure 7 The image is a scanning electron microscope image of the first printed grid lines. The grid line width D2 (the line width at the widest point of the grid line) is about 14 μm, and the line height D1 satisfies: 0 μm < D1 ≤ 6.43 μm. There are obvious thinning and narrowing of the grid lines in some areas, indicating that they are in a critical state of breaking.

[0098] like Figure 8 As shown, Figure 8 The image shows a scanning electron microscope (SEM) image of the grid lines formed by the second printing process. The grid line width D2 ranges from 20.32 μm to 24.03 μm, and the line height D1 ranges from 5 μm to 10.96 μm, showing some variation.

[0099] like Figure 9 As shown, Figure 9 The image shows a scanning electron microscope (SEM) image of the grid lines formed by the third printing process. The grid line width D2 is between 26.25 μm and 28.59 μm, the line height D1 is about 11.58 μm, the aspect ratio is between 40.5% and 44.1%, and the grid line shape is a highly uniform triangular morphology.

[0100] Example 2

[0101] The paste used in this embodiment is HC549-HS type paste; the screen is a narrow linewidth screen with a mesh size of 520-8 (mesh count - wire diameter), an opening width of 8μm, a film thickness of 10μm, a yarn thickness of 15μm, and a tension of 16N; the squeegee angle is set to 65°, and the adhesive strip hardness is 65A; all printing steps are carried out continuously without separating the battery cell from the screen.

[0102] (1) Set the basic printing parameters: screen spacing is 1.6mm, printing speed is 400mm / s, squeegee pressure is 15.6mm, and printing pressure is 50N.

[0103] (2) Perform trial printing using the above basic printing parameters to determine whether the grid lines formed by the trial printing meet the first preset state; if yes, determine the basic printing parameters as the first printing parameters; if not, adjust the basic printing parameters and perform trial printing until the grid lines reach the first preset state, and determine the adjusted printing parameters as the first printing parameters. The adjusted first printing parameters are: screen spacing of 2.2mm, printing speed of 600mm / s, squeegee downward pressure of 15.6mm, and printing pressure of 50N.

[0104] (3) The first printing is performed using the first printing parameters mentioned above to form the first grid line.

[0105] (4) Set the second printing parameters according to the preset rules to ensure that the peak of the grid line formed by printing with the second printing parameters coincides with the trough of the first grid line. The second printing parameters are: screen spacing is 1.6mm, printing speed is 300mm / s, squeegee pressure is 15.6mm, and printing pressure is 50N.

[0106] (5) A second printing is performed using the second printing parameters to form grid lines.

[0107] Each printed grid line was tested using a scanning electron microscope to measure the cross-sectional and bevel morphology of the grid line.

[0108] like Figure 10 As shown, Figure 10 The image shows the scanning electron microscope (SEM) image of the first printed grid lines. The grid line width D2 (the line width at the widest point of the grid line) is about 20.67 μm, the line height D1 is about 7.45 μm, and the aspect ratio is about 36%.

[0109] like Figure 11 As shown, Figure 11 The image shows a scanning electron microscope (SEM) image of the grid lines formed by the second printing process. The grid line width D2 is approximately 21.46 μm, the line height D1 is approximately 12.04 μm, the aspect ratio is approximately 56%, and the grid line shape is a highly uniform triangular morphology.

[0110] According to the test results of the above embodiments, the solar cell grid line preparation method provided in this application ultimately forms a smooth grid line with high uniformity and an approximately triangular cross-section, which improves the aspect ratio (over 40%) and high uniformity of the grid line, thereby improving the light absorption rate of the cell, and increasing Jsc (short-circuit current density) and Eff (cell conversion efficiency).

[0111] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0112] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for fabricating solar cell grid lines, characterized in that, Includes the following steps: Set a first printing parameter, which is configured to make the printed grid lines reach a first preset state; The first printing is performed using the first printing parameters to form the first grid line; Set the second printing parameters according to the preset rules, and perform printing more than once using the second printing parameters; The preset rule includes: the peaks of the grid lines formed by printing with the second printing parameters coincide with the troughs of the first grid lines.

2. The method for fabricating solar cell grid lines according to claim 1, characterized in that, The first printing parameter and the second printing parameter each independently include paste parameters and screen parameters.

3. The method for fabricating solar cell grid lines according to claim 2, characterized in that, The step of setting the first printing parameters includes: Set the basic printing parameters according to the parameters of the paste and screen used; Perform a trial print using the aforementioned basic printing parameters, and determine whether the grid lines formed by the trial print meet the first preset state. If so, the basic printing parameters are determined as the first printing parameters; If not, adjust the basic printing parameters and perform trial printing until the grid lines reach the first preset state, and then determine the adjusted basic printing parameters as the first printing parameters.

4. The method for fabricating solar cell grid lines according to claim 2, characterized in that, After the step of setting the second printing parameters according to the preset rules, the method further includes: performing trial printing with the second printing parameters, and determining whether the grid lines formed by the trial printing meet the second preset state. If so, perform printing more than once using the second printing parameters; If not, adjust the second printing parameters and perform trial printing until the grid lines reach the second preset state, then perform printing once or more using the adjusted second printing parameters; The second preset state refers to the following: when observed under a microscope, the grid lines do not show any burrs; the average linewidth of the grid lines is less than 125% of the average linewidth of the first grid lines; and the relative standard deviation of the grid line height is less than 5%.

5. The method for fabricating solar cell grid lines according to claim 3, characterized in that, The basic printing parameters and the second printing parameters each independently include screen spacing, printing speed, and printing pressure.

6. The method for fabricating solar cell grid lines according to claim 5, characterized in that, The basic printing parameters are: the screen spacing is 1.4mm~1.7mm, the printing speed is 300mm / s~450mm / s, and the printing pressure is 40N~60N.

7. The method for fabricating solar cell grid lines according to claim 1, characterized in that, The printing process uses a knotless screen printing screen.

8. The method for fabricating solar cell grid lines according to any one of claims 1-7, characterized in that, The aspect ratio of the solar cell grid lines is 40% or higher.

9. A solar cell, characterized in that, This includes solar cell grids prepared using the method for preparing solar cell grids according to any one of claims 1-8.

10. A battery assembly, characterized in that, Includes the solar cell described in claim 9.

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