Method for optimizing photoelectric conversion efficiency of solar cell

Abstract

The invention discloses a method for optimizing the photoelectric conversion efficiency of a solar cell, and the method comprises the steps: fixing a printing parameter of a front auxiliary grid line of a first cell, adjusting a first printing parameter for printing a back auxiliary grid line of the first cell, and obtaining a first corresponding relation between the wet weight of secondary slurry and the photoelectric conversion efficiency; fixing printing parameters of secondary grid lines on the back surface of a second battery piece, adjusting second printing parameters for printing secondary grid lines on the front surface of the second battery piece, and obtaining a second corresponding relation between the wet weight of the four-path slurry and the photoelectric conversion efficiency; according to the second slurry wet weight and the fourth slurry wet weight respectively corresponding to the optimal photoelectric conversion efficiency in the first corresponding relation and the second corresponding relation, adjusting a third printing parameter and a fourth printing parameter for printing a back side auxiliary grid line and a front side auxiliary grid line of a third battery piece, and obtaining a third corresponding relation between the second slurry wet weight array and the fourth slurry wet weight array and the photoelectric conversion efficiency; and determining the correlation between the two-pass and four-pass slurry wet weight array and the photoelectric conversion efficiency according to the third corresponding relation.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of renewable energy technology, and in particular, to a method for optimizing photoelectric conversion efficiency of a solar cell. BACKGROUND

[0002] A solar cell is a product that can directly convert solar light energy into electrical energy. The solar cell is mainly made of semiconductor materials such as silicon.

[0003] The photoelectric conversion efficiency of a solar cell refers to the ability of the solar cell to convert solar energy into electrical energy, and is usually expressed as a percentage. The photoelectric conversion efficiency of a solar cell directly determines the performance and benefits of the solar cell in actual application.

[0004] In the production process of a solar cell, controlling the printing parameters of the busbar lines on the front and back surfaces of the solar cell is very important for improving the photoelectric conversion efficiency of the solar cell as much as possible while taking into account the printing cost.

[0005] How to quickly reveal the relationship between the printing parameters of the busbar lines and the photoelectric conversion efficiency through experiments, and to provide data support for the actual production of solar cells, so that the actual production of solar cells has better photoelectric conversion efficiency while taking into account the cost, has become a hot issue of concern in the industry. SUMMARY

[0006] In order to solve the above technical problems, the present disclosure is proposed. Embodiments of the present disclosure provide a method for optimizing photoelectric conversion efficiency of a solar cell.

[0007] According to a first aspect of the present disclosure, a method for optimizing the photoelectric conversion efficiency of a solar cell is provided. The method includes: a two-stage experiment, a four-stage experiment, and a synergistic optimization experiment. The two-stage experiment includes: fixing the printing parameters of the front sub-grid lines of a first solar cell, adjusting the first printing parameters for printing the back sub-grid lines of the first solar cell, printing the sub-grid lines on the back of the first solar cell using the adjusted first printing parameters each time, and obtaining a first correspondence between the wet weight of the two-stage slurry and the photoelectric conversion efficiency of the first solar cell based on each of the first printing parameters. The four-stage experiment includes: fixing the printing parameters of the back sub-grid lines of a second solar cell, adjusting the second printing parameters for printing the front sub-grid lines of the second solar cell, printing the sub-grid lines on the front of the second solar cell using the adjusted second printing parameters each time, and obtaining a first correspondence between the wet weight of the two-stage slurry and the photoelectric conversion efficiency of the first solar cell based on each of the second printing parameters. The second correspondence between the wet weight of the four slurries for the front sub-grid lines of the second solar cell and the photoelectric conversion efficiency of the second solar cell; the collaborative optimization experiment includes: adjusting the third and fourth printing parameters for printing the back sub-grid lines and the front sub-grid lines of the third solar cell based on the wet weight of the two slurries corresponding to the optimal photoelectric conversion efficiency in the first correspondence and the wet weight of the four slurries corresponding to the optimal photoelectric conversion efficiency in the second correspondence; obtaining the third correspondence between the wet weight arrays of the two and four slurries for the back and front sub-grid lines of the third solar cell printed based on each third and fourth printing parameter and the photoelectric conversion efficiency of the third solar cell; determining the correlation between the wet weight arrays of the two and four slurries and the photoelectric conversion efficiency based on the third correspondence; wherein, the correlation is used to determine the printing parameters of the solar cell sub-grid lines to optimize the photoelectric conversion efficiency of the solar cell.

[0008] Based on the above embodiments of this disclosure, a method for optimizing the photoelectric conversion efficiency of a solar cell is provided. By fixing the printing parameters of the front sub-grid lines and adjusting the printing parameters of the back sub-grid lines, a first correspondence between the wet weight of the two-stage paste and the photoelectric conversion efficiency can be obtained. This correspondence clearly reflects the influence of the wet weight of the two-stage paste on the photoelectric conversion efficiency. By fixing the printing parameters of the back sub-grid lines and adjusting the printing parameters of the front sub-grid lines, a second correspondence between the wet weight of the four-stage paste and the photoelectric conversion efficiency can be obtained. This correspondence clearly reflects the influence of the wet weight of the four-stage paste on the photoelectric conversion efficiency. By selecting the wet weights of the two-stage and four-stage paste corresponding to the optimal photoelectric conversion efficiency from the first and second correspondences respectively, and adjusting the printing parameters based on the selected wet weights of the two-stage and four-stage paste, a third correspondence between the arrays of wet weights of the two-stage and four-stage paste and the photoelectric conversion efficiency can be obtained. This correspondence clearly reflects the impact of the combined wet weight of the second and fourth slurry layers on the photoelectric conversion efficiency. Therefore, with minimal experimental steps, the trend of photoelectric conversion efficiency caused by the combined wet weight of the second and fourth slurry layers can be quickly obtained. During solar cell production, this trend can be used to determine the wet weight of the second and fourth slurry layers based on actual production needs, thereby determining the second and fourth printing parameters. This not only helps to rationally control slurry costs but also helps to control the photoelectric conversion efficiency of the solar cells, seeking a balance between slurry costs and photoelectric conversion efficiency. Therefore, the technical solution provided in this disclosure is beneficial for determining printing parameters with fewer experiments, achieving better photoelectric conversion efficiency while considering the production cost of solar cells, thus contributing to a better cost-performance ratio for solar cells.

[0009] The technical solutions of this disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0010] The above and other objects, features, and advantages of this disclosure will become more apparent from the more detailed description of the embodiments thereof in conjunction with the accompanying drawings. The drawings are provided to offer a further understanding of the embodiments of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the disclosure and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0011] Figure 1 This is a flowchart of an embodiment of the method for optimizing the photoelectric conversion efficiency of solar cells disclosed herein;

[0012] Figure 2 A flowchart illustrating one embodiment of the two experiments disclosed herein;

[0013] Figure 3A graph showing the first correspondence obtained from the two experiments of this disclosure;

[0014] Figure 4 A flowchart illustrating one embodiment of the four experiments of this disclosure;

[0015] Figure 5 A graph showing the second correspondence obtained from the four experiments of this disclosure;

[0016] Figure 6 Another graph showing the second correspondence obtained from the four experiments disclosed herein;

[0017] Figure 7 A flowchart illustrating one embodiment of the collaborative optimization experiment of this disclosure;

[0018] Figure 8 A graph of the third correspondence obtained from the collaborative optimization experiment of this disclosure;

[0019] Figure 9 This is another graph of the third correspondence obtained from the collaborative optimization experiment of this disclosure. Detailed Implementation

[0020] Example embodiments according to this disclosure will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this disclosure, and not all embodiments of this disclosure, and it should be understood that this disclosure is not limited to the example embodiments described herein.

[0021] Exemplary method

[0022] The method for optimizing the photoelectric conversion efficiency of solar cells disclosed herein is an experimental method designed to optimize the photoelectric conversion efficiency of solar cells. In one example, the solar cell disclosed herein can be a solar cell based on TOPCon (Tunnel Oxide Passivating Contact) and PERC (Passivated Emitter and Rear Cell) technologies. That is, the first, second, third, and solar cells in the following embodiments can all be solar cells based on TOPCon and PERC technologies. Since solar cells based on TOPCon technology typically have characteristics such as low degradation, high bifaciality, and low temperature coefficient, while solar cells based on PERC technology have characteristics such as reduced electron anti-recombination, the photoelectric conversion efficiency of solar cells based on TOPCon and PERC technologies is improved. By applying the technical solution of this invention to solar cells based on TOPCon and PERC technologies, it is beneficial to further optimize their photoelectric conversion efficiency while taking into account the printing cost of solar cells.

[0023] The technical solution disclosed herein is applicable to applications requiring the printing of main grid lines and sub-grid lines on both the front and back sides of a solar cell. The main grid lines and sub-grid lines on the front side of the solar cell can collaboratively collect the same type of charge carrier (such as electrons or holes), with the current from the sub-grid lines on the front side flowing into the main grid lines. Similarly, the main grid lines and sub-grid lines on the back side of the solar cell can collaboratively collect the same type of charge carrier (such as electrons or holes), with the current from the sub-grid lines on the back side flowing into the main grid lines. The printing in this disclosure typically refers to screen printing.

[0024] Figure 1 This is a flowchart of one embodiment of the method for optimizing the photoelectric conversion efficiency of a solar cell according to this disclosure. Figure 1 The method shown mainly includes the following steps: S100, S101, S102, and S103. The following section details... Figure 1 Each step in the process will be explained separately.

[0025] S100, Second Experiment.

[0026] In this disclosure, "two steps" refers to the second printing process, specifically the process of printing sub-busbars on the back of a solar cell. Sub-busbars (also known as fine back grid lines) are fine metal electrode lines located on the back of a solar cell for collecting and transmitting current. In one application scenario, the sub-busbars can transmit the current they collect to the main back grid lines, which then collect and output the current to an external circuit. The sub-busbars are typically in perpendicular contact with the main back grid lines.

[0027] The first printing process typically precedes the second printing process, and this first printing process refers to the process of printing the main grid lines on the back of the solar cell. The main grid lines on the back of the solar cell (also known as the back main electrode or back collector grid lines, etc.) are metal electrode lines located on the back of the solar cell used to collect the current from the back sub-grid lines and transmit the collected current to the external circuit.

[0028] The two experiments in this disclosure can be specifically described as follows: The printing parameters of the front sub-grid lines of the first solar cell are fixed (i.e., the printing parameters of the front sub-grid lines of the first solar cell are not adjusted), the first printing parameters for printing the back sub-grid lines of the first solar cell are adjusted, and the sub-grid lines are printed on the back of the first solar cell using the adjusted first printing parameters each time. Furthermore, the correspondence between the wet weight of the two slurries for the back sub-grid lines of the first solar cell printed based on each first printing parameter and the photoelectric conversion efficiency of the first solar cell (i.e., the first correspondence) should be obtained. In other words, in the two experiments, the printing parameters that need to be adjusted are the printing parameters for printing the back sub-grid lines of the first solar cell, while the printing parameters for printing the front sub-grid lines of the first solar cell should be kept constant. In addition, the printing parameters for printing the back main grid lines and the printing parameters for printing the front main grid lines of the first solar cell are usually also kept constant (i.e., no adjustment is required).

[0029] The two experiments in this disclosure typically require adjustments to the first printing parameters at least twice. That is, the two experiments usually include multiple sets of experiments, for example, at least three sets. The first printing parameters for each set of experiments are usually different, and the number of first solar cells involved in each set of experiments is usually large; for example, each set of experiments involves hundreds or even thousands of solar cells. In one application scenario, the first solar cell can be a 183.5mm size solar cell, such as a solar cell with a length of 183.5mm.

[0030] The first printing parameter in this disclosure refers to a parameter that can affect the wet weight of the second pass of the paste for the first solar cell. For example, the first printing parameter may include: screen printing speed, screen printing pressure, screen spacing (i.e., screen printing plate spacing), squeegee contact angle, and paste viscosity. The screen printing speed may refer to the squeegee speed. The screen printing pressure may refer to the force exerted by the squeegee on the screen printing plate, and the contact pressure between the screen printing plate and the substrate (e.g., the front / back side of the first solar cell) generated by this force. The screen spacing may refer to the distance between the bottom surface of the screen and the top surface of the substrate; screen spacing can also be called screen printing plate spacing, printing height offset, or separation distance. The squeegee contact angle may refer to the angle formed by the squeegee and the screen printing plate. The paste viscosity may refer to a parameter that reflects the paste's resistance to flow. In some applications, the first printing parameter may also include: screen tension, which is a parameter measuring the elasticity of the screen. The first printing parameters affect the amount of paste output in the second printing pass, which in turn affects the shaping (i.e., shape) of the sub-grid lines on the back of the first solar cell, and consequently the quality of the sub-grid lines on the back of the first solar cell.

[0031] This disclosure allows for the adjustment of one or more of the following parameters, such as screen printing speed, screen printing pressure, screen spacing, squeegee contact angle, and slurry viscosity, based on the current expected value of the second-stage slurry wet weight, so that the actual value of the obtained second-stage slurry wet weight is as close as possible to the expected value of the second-stage slurry wet weight for the second-stage experiment of the first solar cell in this group.

[0032] The paste used in this disclosure typically refers to a raw material used in the screen printing process of solar cell manufacturing, and this paste usually possesses certain properties such as fluidity, thixotropy, and plasticity. The paste used for printing the sub-grid lines on the back of solar cells is called a two-stage paste. The two-stage paste can be silver paste, silver-aluminum paste, copper paste, or a composite paste, etc. Silver paste mainly includes silver powder, glass powder, and an organic carrier. Silver-aluminum paste mainly includes silver powder, aluminum powder, glass powder, and an organic carrier. Copper paste mainly includes copper powder, an organic binder, and a flux. Composite paste can be considered as a paste formed by combining multiple metallic and non-metallic materials, for example, adding nano-carbon materials to silver paste. This disclosure does not limit the proportions of the components in the two-stage paste.

[0033] In the screen printing process, two layers of paste can be transferred and printed onto the back of the solar cell through the mesh of the screen, thereby forming the back-side sub-grid lines of the solar cell. The weight of the two layers of paste printed onto the back of the solar cell before drying is called the wet weight of the two layers of paste. The wet weight of the two layers of paste is an important parameter for measuring the quality of the sub-grid lines. The quality of the back-side sub-grid lines of the first solar cell is usually related to the width of the back-side sub-grid lines. For example, if the back-side sub-grid lines are flattened (e.g., linewidth greater than 26µm), the back-side sub-grid lines may have better quality. This is because a wider linewidth results in a larger cross-sectional area, lower resistance, and a reduced series resistance, which is beneficial for improving the fill factor and output power, thereby improving the photoelectric conversion efficiency. However, a flattened back-side sub-grid line increases shading on the back of the solar cell, reducing the effective light-receiving area and increasing shading loss, which adversely affects the photoelectric conversion efficiency of the solar cell. This disclosure uses a two-layer experiment to achieve a balance between reducing series resistance and reducing shading loss.

[0034] The wet weight of the second-stage slurry in this disclosure specifically refers to the weight of the slurry obtained by weighing after the second-stage slurry is printed on the back of the first solar cell to form the back sub-grid lines, and before the back sub-grid lines are dried. In one application scenario, this disclosure allows the first solar cell to be weighed before the back sub-grid lines are printed on the second-stage screen printing platform to obtain a base weight. After the back sub-grid lines are printed on the first solar cell (e.g., after the first solar cell leaves the second-stage screen printing platform), the first solar cell is weighed again to obtain the sum of the base weight and the wet weight of the second-stage slurry. The wet weight of the second-stage slurry is obtained by calculating the weight difference between the two weighings. Both weighings can be achieved through automatic high-precision weighing. For example, high-precision automatic weighing devices are installed on both the inlet and outlet sides of the second-stage screen printing platform. The first solar cell can be placed on the high-precision automatic weighing devices via a conveyor belt or other equipment, thereby achieving automatic high-precision weighing of the wet weight of the second-stage slurry. For any group of experiments in the two-stage experiment, this disclosure can calculate (e.g., calculate the average value) the wet weight of the second-stage slurry for all or part of the first cells participating in the group of experiments, and use the calculation result (e.g., the average value) as the wet weight of the second-stage slurry obtained in the group of experiments.

[0035] This disclosure allows for the measurement of the photoelectric conversion efficiency of a first solar cell after the main grid lines and sub-grid lines have been successfully printed on the front and back sides of the first solar cell. For example, it allows for the measurement of various indicators reflecting the photoelectric conversion efficiency of the first solar cell, and the measurement of the photoelectric conversion efficiency of the first solar cell based on the measured indicators.

[0036] In an application scenario, the above-mentioned indicators may include one or more of the following: Open Circuit Voltage (UOC), Short-Circuit Current (ISC), Fill Factor (FF), and Series Resistance (RSER). Open Circuit Voltage refers to the terminal voltage of the solar cell in an open-circuit state. Generally, a higher Open Circuit Voltage indicates a higher photoelectric conversion efficiency (PCE). Short-Circuit Current refers to the current in the solar cell when short-circuited. The Short-Circuit Current typically depends on the light intensity and the light-receiving area of ​​the solar cell. Generally, a higher Short-Circuit Current indicates a higher PCE. Fill Factor reflects the ratio of the maximum output power of the solar cell to the product of the Open Circuit Voltage and the Short-Circuit Current. The Fill Factor reflects the influence of the internal resistance characteristics of the solar cell on the output power. Generally, a higher Fill Factor indicates a higher PCE. Series Resistance is typically composed of the bulk resistance of the solar cell, the contact resistance of the silicon wafer, etc. Generally, an increase in series resistance leads to a decrease in the PCE. In addition, the aforementioned indicators may also include at least one of RshuntDfDr (simultaneously measuring RshuntDr and RshuntDf, where RshuntDr represents the parallel resistance measured using a linear regression test with a dark field reverse bias, and RshuntDf represents the parallel resistance measured with a dark field forward bias) and IRev2 (reverse current 2, i.e., the reverse current generated by the solar cell when a -12V reverse voltage is applied). This disclosure does not limit the specific implementation method of obtaining the photoelectric conversion efficiency of the first solar cell using the corresponding indicators.

[0037] S110, four experiments.

[0038] The "four steps" in this disclosure refer to the fourth printing process, specifically the process of printing sub-busbar lines on the front side of the solar cell. The sub-busbar lines (also known as fine front-side grid lines) are fine metal electrode lines located on the front side of the solar cell for collecting and transmitting current. In one application scenario, the sub-busbar lines can transmit the current they collect to the main front-side grid lines, which then collect and output the current to an external circuit. The sub-busbar lines are typically in perpendicular contact with the main front-side grid lines.

[0039] Before the fourth printing process, there are usually first, second, and third printing processes. The third printing process refers to the process of printing the main grid lines on the front side of the solar cell. The main grid lines on the front side of the solar cell (also called the front main electrode or front collector grid lines, etc.) are metal electrode lines located on the front side of the solar cell used to collect the current from the front sub-grid lines and transmit the collected current to the external circuit.

[0040] The four experiments in this disclosure can be specifically described as follows: fixing the printing parameters of the sub-grid lines on the back of the second solar cell (i.e., not adjusting the printing parameters of the sub-grid lines on the back of the second solar cell), adjusting the second printing parameters for printing the sub-grid lines on the front of the second solar cell, and printing sub-grid lines on the front of the second solar cell using the adjusted second printing parameters each time. Furthermore, the correspondence between the wet weight of the four slurries for the front sub-grid lines of the second solar cell printed based on each second printing parameter and the photoelectric conversion efficiency of the second solar cell (i.e., the second correspondence) should be obtained. In other words, in the four experiments, the printing parameters that need to be adjusted are those for printing the sub-grid lines on the front of the second solar cell, while the printing parameters for printing the sub-grid lines on the back of the second solar cell should be kept constant. In addition, the printing parameters for printing the main grid lines on the back of the second solar cell and the printing parameters for printing the main grid lines on the front of the second solar cell are usually also kept constant (i.e., do not need to be adjusted).

[0041] The four experiments in this disclosure typically require adjustments to the second printing parameters at least twice. That is, the four experiments usually include multiple sets of experiments, for example, at least three sets. The second printing parameters for each set of experiments are usually different, and the number of second solar cells involved in each set of experiments is usually large; for example, each set of experiments involves hundreds or even thousands of solar cells. The second solar cells should be the same size and model as the first solar cells; for example, both should use 183.5mm solar cells of the same model. Furthermore, the number of experimental sets in the four experiments can be different from or the same as the number of experimental sets in the two experiments.

[0042] The second printing parameters in this disclosure refer to parameters that can affect the wet weight of the four printing passes of the second solar cell. For example, the second printing parameters may include: screen printing speed, screen printing pressure, screen spacing (i.e., screen printing plate spacing), squeegee contact angle, and printing paste viscosity. Similarly, in some applications, the second printing parameters may also include: screen tension. By affecting the amount of printing paste produced in the fourth printing pass, the second printing parameters influence the shaping of the front-side sub-grid lines of the second solar cell, and consequently, the quality of the back-side sub-grid lines.

[0043] This disclosure allows for adjustments to one or more of the following parameters, such as screen printing speed, screen printing pressure, screen spacing, squeegee contact angle, and paste viscosity, based on the current expected value of the wet weight of the four-pass paste. This adjustment aims to ensure that the actual wet weight of the four-pass paste is as close as possible to the expected value for the four-pass paste wet weight used in the four-pass experiment for the second solar cell in this group. The paste used for printing the front-side sub-grid lines of the solar cell is the four-pass paste, and it can be silver paste, silver-aluminum paste, copper paste, or a composite paste, etc. This disclosure does not limit the proportions of the components in the four-pass paste.

[0044] In the screen printing process, four layers of ink are transferred through the mesh of the screen onto the front side of the solar cell, forming the sub-busbar lines. The weight of the four layers of ink printed onto the front side of the solar cell before drying is called the wet weight of the four layers of ink. The wet weight of the four layers of ink is an important parameter for measuring the quality of the sub-busbar lines. The quality of the sub-busbar lines on the front side of the second cell is usually closely related to the width and height of the sub-busbar lines. For example, if the sub-busbar lines have a narrow linewidth and a high aspect ratio (i.e., the thinner and taller the sub-busbar lines are, the better, such as an aspect ratio greater than 0.42), the sub-busbar lines tend to have better quality. This is because a thinner linewidth reduces the light-shielding area of ​​the sub-busbar lines on the front side of the solar cell, and a taller sub-busbar line increases the cross-sectional area of ​​the sub-busbar lines, which helps to reduce the resistance loss of the sub-busbar lines.

[0045] The wet weight of the four-stage slurry in this disclosure specifically refers to the weight of the slurry obtained by weighing after the four-stage slurry is printed on the front side of the second solar cell to form the front sub-grid lines, and before the front sub-grid lines are dried. In one application scenario, this disclosure allows the second solar cell to be weighed before the front sub-grid lines are printed on the four-stage screen printing platform to obtain a base weight. After the sub-grid lines are printed on the front side of the second solar cell (e.g., after the second solar cell leaves the four-stage screen printing platform), the second solar cell is weighed again to obtain the sum of the base weight and the wet weight of the four-stage slurry. By calculating the weight difference between the two weighings, the wet weight of the four-stage slurry can be obtained. These two weighings can also be achieved through automatic high-precision weighing. For example, high-precision automatic weighing devices are installed on both the inlet and outlet sides of the four-stage screen printing platform. The second solar cell can be placed on the high-precision automatic weighing devices via a conveyor belt or other equipment, thereby achieving automatic high-precision weighing of the wet weight of the four-stage slurry. For any one of the four sets of experiments, this disclosure can calculate (e.g., calculate the average value) the wet weight of the slurry for all or part of the second cells participating in the set of experiments, and use the calculation result (e.g., the average value) as the wet weight of the slurry obtained in the set of experiments.

[0046] This disclosure allows for the measurement of the photoelectric conversion efficiency of a second solar cell after the main grid lines and sub-grid lines have been successfully printed on the front and back sides of the second solar cell. For example, it allows for the measurement of various indicators reflecting the photoelectric conversion efficiency of the second solar cell, and the measurement of the photoelectric conversion efficiency of the second solar cell based on the measured indicators.

[0047] In one application scenario, the aforementioned indicators may also include one or more of the following: open-circuit voltage, short-circuit current, fill factor, series resistance, RshuntDfDr, and IRev2. This disclosure does not limit the specific implementation method for obtaining the photoelectric conversion efficiency of the second solar cell using the corresponding indicators.

[0048] S102, Collaborative Optimization Experiment.

[0049] The collaborative optimization experiment in this disclosure can be specifically described as follows: Based on the wet weight of the second slurry corresponding to the optimal photoelectric conversion efficiency in the first correspondence and the wet weight of the fourth slurry corresponding to the optimal photoelectric conversion efficiency in the second correspondence, the third printing parameters for the back sub-grid lines and the fourth printing parameters for the front sub-grid lines of the third solar cell are adjusted. Sub-grid lines are then printed on the back and front of the third solar cell using the adjusted third and fourth printing parameters. Furthermore, the wet weight arrays of the second and fourth slurry lines for the back and front sub-grid lines of the third solar cell printed based on each third printing parameter should be obtained. In addition, the photoelectric conversion efficiency of the third solar cell should also be obtained. Thus, this disclosure can obtain the correspondence between the wet weight arrays of the second and fourth slurry lines and the photoelectric conversion efficiency of the third solar cell (i.e., the third correspondence).

[0050] As described above, in the collaborative optimization experiment, the printing parameters that need to be adjusted are the printing parameters for printing the sub-grid lines on the back of the third cell and the printing parameters for printing the sub-grid lines on the front of the third cell, while the printing parameters for printing the main grid lines on the back of the third cell and the printing parameters for printing the main grid lines on the front of the third cell are usually kept in place.

[0051] The collaborative optimization experiments in this disclosure typically require adjustments to the third and fourth printing parameters at least twice. That is, the collaborative optimization experiments usually include multiple sets of experiments, for example, at least two sets. The third printing parameters for each set are usually different, and the fourth printing parameters for each set are also usually different. Furthermore, each set of experiments typically involves a large number of third solar cells, such as hundreds or even thousands of cells. In addition, the third, second, and first solar cells should use the same cell size and model; for example, they should all use 183.5mm solar cells of the same model.

[0052] In this disclosure, the third printing parameter refers to a parameter that can affect the wet weight of the second pass slurry in the third solar cell, while the fourth printing parameter refers to a parameter that can affect the wet weight of the fourth pass slurry in the third solar cell. For example, both the third and fourth printing parameters can include: screen printing speed, screen printing pressure, screen spacing, squeegee contact angle, slurry viscosity, and screen tension, etc. The third and fourth printing parameters affect the slurry output of the second and fourth passes, thereby affecting the shaping of the sub-grid lines on the back and front sides of the third solar cell, and consequently affecting the quality of the sub-grid lines on the back and front sides of the third solar cell.

[0053] This disclosure allows for the adjustment of one or more parameters, such as screen printing speed, screen printing pressure, screen spacing, squeegee contact angle, and paste viscosity, based on the current expected values ​​of the second-pass slurry wet weight (e.g., the second-pass slurry wet weight corresponding to the optimal photoelectric conversion efficiency) and the fourth-pass slurry wet weight (e.g., the fourth-pass slurry wet weight corresponding to the optimal photoelectric conversion efficiency). This adjustment aims to make the actual values ​​of the second-pass slurry wet weight and the fourth-pass slurry wet weight as close as possible to the expected values ​​of the second-pass slurry wet weight and the fourth-pass slurry wet weight for the second and fourth passes of the second and fourth passes of the third solar cell in this group.

[0054] In one application scenario, this disclosure allows for the following steps: First, before the third solar cell enters the second-stage screen printing platform for back-side sub-grid line printing, a base weight is obtained. Then, after the back-side sub-grid lines are printed (e.g., after the third solar cell leaves the second-stage screen printing platform), the third solar cell is weighed again to obtain the sum of the base weight and the wet weight of the four-stage paste. The wet weight of the second-stage paste is obtained by calculating the weight difference between the two weighings. Similarly, this disclosure allows for the following steps: First, before the third solar cell enters the fourth-stage screen printing platform for front-side sub-grid line printing, a base weight is obtained. Then, after the front-side sub-grid lines are printed (e.g., after the third solar cell leaves the fourth-stage screen printing platform), the third solar cell is weighed again to obtain the sum of the base weight and the wet weight of the four-stage paste. The wet weight of the four-stage paste is obtained by calculating the weight difference between the two weighings. All of the above weighings can be performed using automated, high-precision weighing. For any group of experiments in the collaborative optimization experiment, this disclosure can calculate (e.g., average calculation) the wet weight of the second and fourth slurries of all or some of the third cells participating in the group of experiments, and use the calculation results (e.g., average) as the wet weight of the second and fourth slurries obtained in the group of experiments. By accumulating the wet weight of the second and fourth slurries obtained in the group of experiments, the wet weight array of the second and fourth slurries in the group of experiments can be obtained.

[0055] This disclosure allows for the measurement of the photoelectric conversion efficiency of a third solar cell after the main grid lines and sub-grid lines have been successfully printed on the front and back sides of the third solar cell. For example, it allows for the measurement of various indicators reflecting the photoelectric conversion efficiency of the third solar cell, and the measurement of the photoelectric conversion efficiency of the third solar cell based on the measured indicators.

[0056] In one application scenario, the aforementioned metrics may also include one or more of the following: open-circuit voltage, short-circuit current, fill factor, series resistance, RshuntDfDr, and IRev2. This disclosure does not limit the specific implementation method for obtaining the photoelectric conversion efficiency of the third solar cell using these metrics.

[0057] S103. Based on the third correspondence obtained from the collaborative optimization experiment, determine the correlation between the wet weight array of the second and fourth slurries and the photoelectric conversion efficiency.

[0058] The correlation here can include positive and negative correlations. That is, the correlation can represent the changing trend of photoelectric conversion efficiency formed by the arrays of wet weights of the second and fourth slurries. Therefore, in the solar cell production process, the expected values ​​of the wet weights of the second and fourth slurries can be determined based on this trend. The second-pass printing parameters can be set based on the expected wet weight of the second slurry, and the fourth-pass printing parameters can be set based on the expected wet weight of the fourth slurry, to optimize the photoelectric conversion efficiency of the solar cell and achieve an ideal balance between slurry cost and photoelectric conversion efficiency. This allows for effective control over both slurry cost and photoelectric conversion efficiency in solar cells. In one application scenario, the correlation in this disclosure can be represented by visual graphs such as line graphs or bar charts.

[0059] In one example, a specific example of the two experiments disclosed herein is as follows: Figure 2 As shown. It should be noted that the following refers to... Figure 2 The description omits some manufacturing processes of solar cells, such as printing main grid lines on the front and back of the first cell and drying processes.

[0060] Figure 2 In the middle, S200, the second experiment begins.

[0061] In this step, the necessary data for the second experiment can be obtained, such as the total number of first cells to participate in the second experiment (e.g., 1000 or 2000 cells), the required number of experimental groups in the second experiment (e.g., 3 or 5 groups), and the number of first cells in each experimental group in the second experiment (e.g., 200 or 300 cells).

[0062] S201. Adjust the current first and second printing parameters, and print sub-grid lines on the back of the first cell according to the adjusted current first and second printing parameters.

[0063] This disclosure allows for the adjustment of the current first and second printing parameters based on the expected trend of the wet weight of the second slurry in this group of experiments (e.g., an increase of 5 mg each time). For example, the expected trend of the wet weight of the second slurry in this group of experiments could be to increase or decrease the corresponding value based on the current wet weight of the second slurry. It should be noted that after adjusting the current first and second printing parameters, if the wet weight of the second pass slurry obtained in this group of experiments matches the expected trend mentioned above (for example, the expected trend is to increase the corresponding value, and the actual increase is basically consistent with the corresponding value, such as the actual increase being within a preset range), then the adjustment of the current first and second printing parameters can be considered successful. However, if the wet weight of the second pass slurry obtained in this group of experiments does not match the expected trend mentioned above (for example, the expected trend is to increase the corresponding value, but the actual increase differs significantly from the corresponding value, or it does not increase but decreases), then the adjustment of the current first and second printing parameters can be considered a failure. Measures such as replacing the printing components (i.e., the hardware equipment used for printing), such as replacing the squeegee or the screen, should be considered to facilitate re-testing, thereby helping to ensure the reliability of the data of the first correspondence obtained in this disclosure.

[0064] This disclosure allows for the first printing of main grid lines on the back of a first solar cell using the current printing parameters. After successful printing of the main grid lines on the back of the first solar cell, the weight of the first solar cell is measured to obtain a base weight (hereinafter referred to as the first weight). Then, using the current first and second printing parameters, sub-grid lines are printed on the back of the first solar cell. After successful printing of the sub-grid lines on the back of the first solar cell, the weight of the first solar cell is measured again to obtain another weight (hereinafter referred to as the second weight).

[0065] S202, Obtain the wet weight of the second slurry on the back of the first solar cell's sub-grid line.

[0066] This disclosure allows obtaining the wet weight of the second slurry on the back of the first solar cell by calculating the difference between the second weight and the first weight. When there are multiple first solar cells participating in a set of experiments, the average wet weight of the second slurry for all first solar cells can be calculated and recorded. Alternatively, this disclosure can also calculate the average wet weight of the second slurry for a subset of the first solar cells and record the calculated average wet weight, for example, by removing obviously abnormal wet weights and calculating the average wet weight of the remaining wet weights.

[0067] This disclosure can also obtain the first shaping parameters (such as the linewidth of the sub-grid lines on the back of the first solar cell) in the second-stage experiment. When there are multiple first solar cells participating in a set of experiments, the average value of the first shaping parameters (such as the average linewidth) of all the sub-grid lines on the back of the first solar cells can be calculated and recorded. Of course, the average value of the first shaping parameters of some of the sub-grid lines on the back of the first solar cells can also be calculated and recorded. For example, obviously abnormal first shaping parameters can be removed, and the average value of the remaining first shaping parameters can be calculated. By adding the first shaping parameter to the first correspondence, it is beneficial to fully understand the influence of the wet weight of the second-stage slurry on the shaping of the sub-grid lines on the back of the solar cell, as well as the correlation between the shaping of the sub-grid lines on the back of the solar cell and the photoelectric conversion efficiency.

[0068] S203. Based on the current first and fourth printing parameters, print sub-grid lines on the front side of the first cell.

[0069] This disclosure allows for the initial printing of main grid lines on the front side of a first solar cell using the current three-stage printing parameters. After successful printing of the main grid lines on the front side of the first solar cell, sub-grid lines are then printed on the front side of the first solar cell using the current first and fourth-stage printing parameters. Furthermore, in each set of experiments included in the two-stage experiment, the current first-stage printing parameters, the current three-stage printing parameters, and the current first and fourth-stage printing parameters are not adjusted and remain in a constant state.

[0070] S204. Obtain the first photoelectric conversion efficiency of the first solar cell, and record the correspondence between the wet weight of the second slurry on the back of the first solar cell and the first photoelectric conversion efficiency, i.e., the first correspondence.

[0071] This disclosure allows the photoelectric conversion efficiency of a first solar cell to be obtained by measuring various indicators that reflect its photoelectric conversion efficiency. For example, some or all of the open-circuit voltage, short-circuit current, fill factor, series resistance, RshuntDfDr, and IRev2 of the first solar cell can be measured, and the photoelectric conversion efficiency of the first solar cell can be calculated using the measured data.

[0072] When there are multiple first solar cells participating in a set of experiments, the parameters of all first solar cells can be measured, and the photoelectric conversion efficiency of each first solar cell can be calculated using the measured data. Then, the average photoelectric conversion efficiency of all first solar cells can be calculated, and the correspondence between this average photoelectric conversion efficiency and the average wet weight of the second slurry can be recorded. Alternatively, the average photoelectric conversion efficiency of a subset of the first solar cells can be calculated, and the correspondence between this average photoelectric conversion efficiency and the average wet weight of the second slurry can be recorded. For example, obviously abnormal photoelectric conversion efficiencies can be removed, and the average of the remaining photoelectric conversion efficiencies can be calculated.

[0073] In one embodiment, when the first molding parameters are obtained in this disclosure, the correspondence between the first molding parameters, photoelectric conversion efficiency, and wet weight of the second slurry can be recorded. For example, the correspondence between the average value of the first molding parameters (such as the average linewidth of the sub-gate line on the back of the first solar cell), the average photoelectric conversion efficiency, and the average wet weight of the second slurry can be recorded to obtain the first correspondence of the set of experiments.

[0074] S205. Determine whether the number of experiments (i.e. the number of experimental groups) in the second experiment meets the requirements of the first experiment. If the requirements of the first experiment are not met, return to S201. If the requirements of the first experiment are met, proceed to S206.

[0075] The first number requirement in this disclosure refers to the requirement for the number of experiments in the two experiments. The first number requirement can be set according to the actual situation. For example, the first number requirement can be: the number of experiments in the two experiments is not less than 3 or 5, etc.

[0076] S206. End the second experiment, meaning the second experiment has been successfully completed.

[0077] An example of the results of two experiments is as follows: Figure 3 As shown.

[0078] Figure 3 In the graph, the horizontal axis represents the number of experiments, the left vertical axis represents the wet weight of the second slurry (in milligrams), and the right vertical axis represents the photoelectric conversion efficiency (%). The five points on the upper curve represent the photoelectric conversion efficiencies in the five experiments, which are 26.178, 26.223, 26.247, 26.186, and 26.196, respectively. The five points on the lower curve represent the wet weights of the second slurry in the five experiments, which are 34.60, 36.6, 38.00, 34.5, and 35.00, respectively. Figure 3 The data from the first experiment can be considered as the basic experimental data. Figure 3 The data from the last experiment can be considered as the reconstructed experimental data. The basic experimental data and the reconstructed experimental data can be found in the descriptions of the basic and reconstructed experiments in subsequent embodiments.

[0079] In one example, a specific example of the four experiments disclosed herein is as follows: Figure 4 As shown.

[0080] Figure 4 In the middle, S400, start four experiments.

[0081] This step can obtain the data required for the experiment, such as the total number of second cells that need to participate in the four experiments (e.g., 1000 or 2000 cells), the required number of experimental groups for the four experiments (e.g., 4 or 5 times), and the number of second cells participating in each group of the four experiments (e.g., 200 or 300 cells).

[0082] S401. Based on the current second printing parameters, print sub-grid lines on the back of the second cell.

[0083] This disclosure allows for the printing of main grid lines on the back of a second solar cell using the current first-pass printing parameters. After successful printing of the main grid lines on the back of the second solar cell, sub-grid lines are then printed on the back of the second solar cell using the current second-pass printing parameters. Furthermore, in each experiment included in the two-pass experiment, the current first-pass printing parameters and the current second-pass printing parameters are never adjusted.

[0084] S402. Adjust the current second and fourth printing parameters, and print sub-grid lines on the front side of the second cell according to the adjusted current second and fourth printing parameters.

[0085] This disclosure allows for the adjustment of the current second and fourth printing parameters based on the expected change trend of the wet weight of the four pulps in this group of experiments (e.g., an increase of 2 mg each time). For example, the expected change trend of the wet weight of the four pulps in this group of experiments could be to increase or decrease the corresponding value based on the current wet weight of the second and fourth pulps. It should be noted that after adjusting the current second and fourth printing parameters, if the wet weight of the four printing plates obtained in this group of experiments matches the expected trend mentioned above (for example, the expected trend is to increase the corresponding value, and the actual increase is basically consistent with the corresponding value, such as the actual increase being within a preset range), then the adjustment of the current second and fourth printing parameters can be considered successful. However, if the wet weight of the four printing plates obtained in this group of experiments does not match the expected trend mentioned above (for example, the expected trend is to increase the corresponding value, but the actual increase differs significantly from the corresponding value, or it does not increase but decreases), then the adjustment of the current second and fourth printing parameters can be considered a failure. Measures such as replacing the printing components (i.e., the hardware equipment used for printing), such as replacing the squeegee or the screen, should be considered to facilitate re-testing, thereby helping to ensure the reliability of the second correspondence obtained in this disclosure.

[0086] This disclosure allows for the initial printing of main grid lines on the front side of a second solar cell using the current three-stage printing parameters. After successful printing of the main grid lines, the weight of the second solar cell is measured to obtain a base weight (hereinafter referred to as the third weight). Then, using the adjusted current second and fourth-stage printing parameters, sub-grid lines are printed on the front side of the second solar cell. After successful printing of the sub-grid lines, the weight of the second solar cell is measured again to obtain another weight (hereinafter referred to as the fourth weight). Furthermore, the current three-stage printing parameters are never adjusted in any of the experiments included in the four-stage experiment.

[0087] S403. Obtain the wet weight of the four slurries on the front sub-grid lines of the second solar cell.

[0088] This disclosure allows obtaining the wet weight of the four slurry layers on the front side of the second solar cell by calculating the difference between the fourth and third weights. When there are multiple second solar cells participating in a set of experiments, the average wet weight of the four slurry layers for all second solar cells can be calculated and recorded. Alternatively, this disclosure can also calculate and record the average wet weight of the four slurry layers for a subset of the second solar cells, for example, by removing obviously abnormal wet weights and calculating the average wet weight of the remaining four slurry layers.

[0089] Furthermore, this disclosure can also obtain the second shaping parameters (such as linewidth and lineheight of the front sub-grid lines of the second solar cell) in four experiments. When there are multiple second solar cells participating in a set of experiments, the average value of the second shaping parameters (such as the average linewidth and lineheight) of all the front sub-grid lines of the second solar cells can be calculated, and the ratio of the average linewidth to the average lineheight can be recorded. Of course, the average value of the second shaping parameters of some of the front sub-grid lines of the second solar cells can also be calculated, and the ratio of the average linewidth to the average lineheight can be recorded. For example, obviously abnormal linewidths and lineheights can be removed, and the average linewidth and lineheight of the remaining lines can be calculated, and the ratio of the average linewidth to the average lineheight can be recorded.

[0090] S404. Obtain the second photoelectric conversion efficiency of the second solar cell, and record the correspondence between the wet weight of the four slurries on the front side of the second solar cell and the second photoelectric conversion efficiency, i.e., the second correspondence.

[0091] This disclosure allows the photoelectric conversion efficiency of a second solar cell to be obtained by measuring various indicators that reflect its photoelectric conversion efficiency. For example, some or all of the open-circuit voltage, short-circuit current, fill factor, series resistance, RshuntDfDr, and IRev2 of the second solar cell can be measured, and the photoelectric conversion efficiency of the second solar cell can be calculated using the measured data.

[0092] When multiple second solar cells are involved in a set of experiments, the parameters of all second solar cells can be measured, and the photoelectric conversion efficiency (PCE) of each second solar cell can be calculated using the measured data. Then, the average PCE of all second solar cells can be calculated, and the correspondence between this average PCE and the average wet weight of the second slurry can be recorded. Alternatively, the average PCE of a subset of the second solar cells can be calculated, and the correspondence between this average PCE and the average wet weight of the second slurry can be recorded. For example, obviously abnormal PCEs can be removed, and the average of the remaining PCEs can be calculated.

[0093] In one embodiment, where a second molding parameter is also obtained in this disclosure, the correspondence between the second molding parameter, photoelectric conversion efficiency, and the wet weight of the four slurries can be recorded. For example, the correspondence between the average aspect ratio of the front sub-grid lines of the second solar cell, the average photoelectric conversion efficiency, and the average wet weight of the four slurries can be recorded to obtain the second correspondence for this set of experiments. By adding the second molding parameter to the second correspondence, it is beneficial to fully understand the influence of the wet weight of the four slurries on the molding of the front sub-grid lines of the solar cell, and the influence of the molding of the front sub-grid lines of the solar cell on the photoelectric conversion efficiency.

[0094] S405. Determine whether the number of experiments in the four stages meets the second requirement. If it does not meet the second requirement, fix the current second printing parameters and return to S401. If it meets the second requirement, proceed to S406.

[0095] The second requirement in this disclosure refers to the requirement for the number of experiments in the four experiments. The second requirement can be set according to the actual situation. For example, the second requirement can be: the number of experiments in the four experiments is not less than 4 or 5, etc.

[0096] S406. End of four experiments, meaning the four experiments have been successfully completed.

[0097] An example of the results of the four experiments is as follows: Figure 5 As shown.

[0098] Figure 5 In the figure, the horizontal axis represents the number of experiments, the vertical axis on the left represents the wet weight of the four slurries (in milligrams), and the vertical axis on the right represents the photoelectric conversion efficiency (%). Figure 5 The five points on one curve represent the photoelectric conversion efficiency in the five experiments, which are 26.187, 26.237, 26.109, 26.178 and 26.196, respectively. The five points on the other curve represent the wet weight of the slurry in the four experiments, which are 34.30, 36.5, 38.30, 34.9 and 35.00, respectively. Figure 5 The data from the first experiment can be considered as the basic experimental data. Figure 5 The data from the last experiment can be considered as the reconstructed experimental data. The basic experimental data and the reconstructed experimental data can be found in the descriptions of the basic and reconstructed experiments in subsequent embodiments.

[0099] Figure 5 The points in can also form Figure 6 . Figure 6 The horizontal axis represents the wet weight of the four slurries (in milligrams), and the vertical axis represents the photoelectric conversion efficiency (%). Figure 6 The dashed line in the figure represents the change in photoelectric conversion efficiency caused by the wet weight of the four slurries changing from 34.3 to 35, which can be approximated as a straight line.

[0100] In one example, one example of the collaborative optimization experiment of this disclosure is as follows: Figure 7 As shown.

[0101] Figure 7 In the middle, S700, the collaborative optimization experiment began.

[0102] This step can obtain the data required for the experiment, such as the total number of third cells to participate in the collaborative optimization experiment (e.g., 1000 or 2000 cells), the required number of experimental groups for the collaborative optimization experiment (e.g., 3 or 4 groups), and the number of third cells in each experimental group participating in the collaborative optimization experiment (e.g., 200 or 300 cells).

[0103] S701. Select the wet weight of the second slurry corresponding to the optimal photoelectric conversion efficiency from the first correspondence, and select the wet weight of the fourth slurry corresponding to the optimal photoelectric conversion efficiency from the second correspondence.

[0104] For example, Figure 3 In the second-stage experiment, the optimal photoelectric conversion efficiency was 26.247, and the corresponding wet weight of the second-stage slurry was 38. For example, Figure 5 In the experiment, the optimal photoelectric conversion efficiency was 26.237, and the wet weight of the slurry in the four experiments corresponding to this optimal photoelectric conversion efficiency was 36.5.

[0105] S702. Set the current third and second printing parameters based on the selected second-pass wet weight of the paste, and set the current third and fourth printing parameters based on the selected fourth-pass wet weight of the paste.

[0106] This disclosure allows for the adjustment of the current third and fourth printing parameters based on the selected wet weight of the second pass slurry, and then the adjustment of the current third and fourth printing parameters based on the selected wet weight of the fourth pass slurry. It should be noted that after adjusting the current third and fourth printing parameters, if the wet weights of the second and fourth passes obtained in this experiment are only slightly different from the selected wet weights (e.g., the difference falls within a preset range), then the adjustment of the current third and fourth printing parameters can be considered successful. Conversely, if the wet weights of the second and fourth passes obtained in this experiment are significantly different from the selected wet weights (e.g., the difference does not fall within a preset range), then the adjustment of the current third and fourth printing parameters can be considered a failure. In such cases, measures such as replacing the printing components (i.e., the hardware used for printing), such as replacing the squeegee or the screen, should be considered to allow for a re-test.

[0107] S703. Based on the current third and second printing parameters, print sub-grid lines on the back of the third cell and obtain the wet weight of the second slurry for the sub-grid lines on the back of the third cell.

[0108] This disclosure allows for the initial printing of main grid lines on the back of a third solar cell using the current printing parameters. After successful printing of the main grid lines, the weight of the third solar cell is measured to obtain a base weight (hereinafter referred to as the fifth weight). Then, using the current second-third printing parameters, sub-grid lines are printed on the back of the third solar cell. After successful printing of the sub-grid lines, the weight of the third solar cell is measured again to obtain another weight (hereinafter referred to as the sixth weight). Furthermore, in each experiment included in the collaborative optimization experiment, the current printing parameters are never adjusted.

[0109] S704. Based on the current third and fourth printing parameters, print sub-grid lines on the front side of the third cell and obtain the wet weight of the four slurries for the sub-grid lines on the front side of the third cell.

[0110] This disclosure allows for the initial printing of main grid lines on the front side of a third solar cell using the current three-stage printing parameters. After successful printing of the main grid lines, the weight of the third solar cell is measured to obtain a base weight (hereinafter referred to as the seventh weight). Then, using the current second and fourth-stage printing parameters, sub-grid lines are printed on the front side of the third solar cell. After successful printing of the sub-grid lines, the weight of the third solar cell is measured again to obtain another weight (hereinafter referred to as the eighth weight). Furthermore, the current three-stage printing parameters are never adjusted in any of the experiments included in the collaborative optimization experiment.

[0111] S705. Record the wet weight of the second slurry on the back side of the third cell and the wet weight of the fourth slurry on the front side of the third cell as a wet weight array of the second and fourth slurries.

[0112] This disclosure allows obtaining the wet weight of the second-stage slurry for the sub-grid lines on the back of the third solar cell by calculating the difference between the sixth and fifth weights. When multiple third solar cells participate in a set of experiments, the average wet weight of the second-stage slurry for all third solar cells can be calculated and recorded. Alternatively, this disclosure can calculate and record the average wet weight of the second-stage slurry for a subset of the third solar cells, for example, by removing obviously abnormal wet weights and calculating the average wet weight of the remaining cells.

[0113] This disclosure allows obtaining the wet weight of the four slurries on the front side of the third solar cell by calculating the difference between the eighth and seventh weights. When multiple third solar cells participate in a set of experiments, the average wet weight of the four slurries for all third solar cells can be calculated and recorded. Alternatively, this disclosure can also calculate and record the average wet weight of the four slurries for a subset of the third solar cells, for example, by removing obviously abnormal wet weights and calculating the average wet weight of the remaining four slurries.

[0114] The wet weight array of the second and fourth slurries in this disclosure can be an array containing the average wet weight of the second slurry and the average wet weight of the fourth slurry. In addition, the array can also contain the sum of the average wet weight of the second slurry and the average wet weight of the fourth slurry.

[0115] In addition, this disclosure can also obtain the third shaping parameters (such as the line width of the sub-grid on the back of the third cell) and the fourth shaping parameters (such as the line width and line height of the sub-grid on the front of the third cell) in the collaborative optimization experiment. When there are multiple third cells participating in a set of experiments, the average value of the third shaping parameters (such as the average line width) and the average value of the fourth shaping parameters (such as the average line width and line height) of the sub-grid on the back of all third cells can be calculated, and the average line width of the sub-grid on the back and the ratio of the average line width and line height of the sub-grid on the front can be recorded. Of course, the average third shaping parameter of some third cell back sub-grid lines and the average fourth shaping parameter of some third cell front sub-grid lines can also be calculated, and the average linewidth of the back sub-grid lines and the ratio of the average lineheight to the average linewidth of the front sub-grid lines can be recorded. For example, the linewidth of obviously abnormal back sub-grid lines and the linewidth and lineheight of obviously abnormal front sub-grid lines can be removed, and the average linewidth of the remaining back sub-grid lines and the ratio of the average lineheight to the average linewidth of the remaining front sub-grid lines can be calculated.

[0116] S706. Obtain the third photoelectric conversion efficiency of the third cell and record the third correspondence between the wet weight array of the second and fourth slurries and the third photoelectric conversion efficiency.

[0117] This disclosure allows the photoelectric conversion efficiency of a third solar cell to be obtained by measuring various indicators that reflect its photoelectric conversion efficiency. For example, some or all of the open-circuit voltage, short-circuit current, fill factor, series resistance, RshuntDfDr, and IRev2 of the third solar cell can be measured, and the photoelectric conversion efficiency of the third solar cell can be calculated using the measured data.

[0118] When multiple third-stage solar cells are involved in a set of experiments, the parameters of all third-stage solar cells can be measured, and the photoelectric conversion efficiency (PCE) of each third-stage solar cell can be calculated using the measured data. Then, the average PCE of all third-stage solar cells can be calculated, and the correspondence between this average PCE and the wet weight arrays of the second and fourth stage slurries can be recorded. Alternatively, the average PCE of a subset of the third-stage solar cells can be calculated, and the correspondence between this average PCE and the wet weight arrays of the second and fourth stage slurries can be recorded. For example, obviously abnormal PCEs can be removed, and the average of the remaining PCEs can be calculated.

[0119] In one embodiment, where the third and fourth molding parameters are also obtained in this disclosure, the correspondence between the third and fourth molding parameters, the photoelectric conversion efficiency, and the wet weight arrays of the second and fourth slurries can be recorded. For example, the correspondence between the average linewidth of the back sub-grid lines, the average aspect ratio of the front sub-grid lines, the average photoelectric conversion efficiency, and the average wet weight of the four slurries can be recorded to obtain the third correspondence for this set of experiments. By adding the third and fourth molding parameters to the third correspondence, it is beneficial to fully understand the impact of the superposition of the wet weights of the second and fourth slurries on the molding of the back and front sub-grid lines of the solar cell, and the impact of the molding of the back and front sub-grid lines of the solar cell on the photoelectric conversion efficiency.

[0120] S707. Determine whether the number of collaborative optimization experiments meets the requirement for the third time. If it does not meet the requirement, proceed to S708. If it meets the requirement, proceed to S709.

[0121] S708. Adjust the current third and second printing parameters and the third and fourth printing parameters, and return to S703.

[0122] This disclosure allows for the adjustment of the current second and third / fourth printing parameters based on the trend of gradually decreasing wet weight arrays of the second and fourth passes in the next set of experiments. For example, the gradual decrease in the wet weight arrays of the second and fourth passes in the next set of experiments can specifically mean that the current wet weight of the second pass and the current wet weight of the fourth pass are each reduced by the same value, i.e., reduced by the same amount. Alternatively, the wet weight arrays of the second and fourth passes in the next set of experiments can also be gradually increased, for example, by increasing the current wet weight of the second pass and the current wet weight of the fourth pass by the same value, i.e., increased by the same amount.

[0123] It should be noted that after adjusting the current second and third pass printing parameters, if the change in the wet weight array of the second and fourth pass slurries obtained in the next set of experiments (e.g., decrease / increase) meets expectations, then the adjustment of the current second and third pass printing parameters is successful. If the change in the wet weight array of the second and fourth pass slurries obtained in the next set of experiments (e.g., decrease / increase) does not meet expectations, then the adjustment of the current second and third pass printing parameters is considered a failure. In this case, measures such as replacing the printing components (i.e., the hardware used for printing), such as replacing the squeegee or screen, should be considered to facilitate re-testing, thereby ensuring the reliability of the third correspondence data obtained in this disclosure. Furthermore, although the current second and third pass printing parameters are adjusted based on the principle of simultaneously reducing the wet weight of the second and fourth pass slurries by the same amount, the actual decrease in the wet weight of the second and fourth pass slurries obtained when printing sub-grid lines based on the adjusted current second and third pass printing parameters may not be the same. The same principle applies to increasing the wet weight by the same amount. By adjusting the current third and fourth printing parameters based on the principle of simultaneously decreasing / increasing the wet weight of the second and fourth printing passes by the same amount, it is beneficial to quickly and effectively complete the collaborative optimization experiment.

[0124] S709. End the collaborative optimization experiment.

[0125] An example of the results of the collaborative optimization experiment is as follows: Figure 8 As shown.

[0126] Figure 8 In the figure, the horizontal axis represents the number of experiments, the vertical axis on the left represents the wet overlap of the second and fourth slurry (in milligrams), and the vertical axis on the right represents the photoelectric conversion efficiency (%). Figure 8 The four points on one curve represent the photoelectric conversion efficiency in the four experiments, which are 26.263, 26.325, 26.294 and 26.252, respectively. The four points on the other curve represent the wet overlap values ​​of the two-pass and four-pass slurry in the four experiments, which are 67.8, 73.3, 69.4 and 68.6, respectively. Figure 8 The data from the first experiment can be considered as the basic experimental data. Figure 8 The data from the last experiment can be considered as the reconstructed experimental data. The basic experimental data and the reconstructed experimental data can be found in the descriptions of the basic and reconstructed experiments in subsequent embodiments.

[0127] Figure 8 The points in can also form Figure 9 . Figure 9 The horizontal axis represents the wet overlap of the second and fourth passes of slurry (in milligrams), and the vertical axis represents the photoelectric conversion efficiency (%). Figure 9The dashed line in the figure represents the change in photoelectric conversion efficiency caused by the wet overlap of the second and fourth slurries from 67.8 to 69.4, which can be approximated as a straight line.

[0128] In one application scenario, this disclosure also requires basic experiments and reduction experiments. The basic experiments (also known as baseline experiments) can be performed before the two-stage, four-stage, and collaborative optimization experiments, while the reduction experiments can be performed after the two-stage, four-stage, and collaborative optimization experiments. Alternatively, this disclosure can perform the basic experiments and reduction experiments before and after the two-stage experiments, before and after the four-stage experiments, and before and after the collaborative optimization experiments. Basic experiments and reduction experiments help ensure the reliability of the data obtained from the two-stage, four-stage, and collaborative optimization experiments.

[0129] The printing parameters used in the basic experiment for the first, second, third, and fourth passes can be referred to as basic printing parameters or reference printing parameters. These basic printing parameters can be empirical values. In a given application scenario, the printing parameters for each pass in solar cell production are currently set based on the target wet weight of the paste for each pass. For example, the second pass printing parameters might be set based on a target wet weight of 34.3 mg / L for the second pass, and the fourth pass printing parameters might be set based on a target wet weight of 33.5 mg / L for the fourth pass. This disclosure allows for screen printing of solar cells using these basic printing parameters, and the acquisition of a basic wet weight value for the second pass (also referred to as a reference value), a basic wet weight value for the fourth pass (also referred to as a reference value), and a basic value for photoelectric conversion efficiency (also referred to as a reference value).

[0130] The printing parameters used in the reduction experiment—first-pass, second-pass, third-pass, and fourth-pass printing parameters—can be referred to as reduction printing parameters. These parameters can be based on the first-pass and third-pass printing parameters currently used in solar cell production, which are set based on the wet weight of the first to third pass slurry. They can also be based on the wet weight baselines of the second and fourth pass slurry passes. This disclosure allows for screen printing of solar cells using these reduction printing parameters, obtaining reduced wet weight values ​​for the second and fourth pass slurry passes, as well as reduced photoelectric conversion efficiency values.

[0131] If the deviations of the baseline wet weight values ​​of the second and fourth slurries and the baseline values ​​of photoelectric conversion efficiency from the restored values ​​of the second and fourth slurries wet weight and the restored values ​​of photoelectric conversion efficiency meet the deviation requirements (e.g., the deviations are within the predetermined deviation range), then the experimental data obtained from the second-stage, fourth-stage, and collaborative optimization experiments of this disclosure can be used as valid experimental data. That is, the changes in photoelectric conversion efficiency in each experiment are mainly related to the changes in the wet weight of the second and / or fourth slurries. Otherwise, the interfering factors that cause large deviations in the experimental data should be investigated, and after eliminating the corresponding interfering factors, the corresponding experiments should be repeated, such as repeating the second-stage, fourth-stage, and collaborative optimization experiments.

[0132] The indicators used to determine the photoelectric conversion efficiency obtained from the basic experiments of this disclosure (the row where banseline is located in Table 1), the indicators used to determine the photoelectric conversion efficiency obtained from the three sets of experiments in the two-stage experiments, the indicators used to determine the photoelectric conversion efficiency obtained from the two sets of experiments in the collaborative optimization experiments, and the indicators used to determine the photoelectric conversion efficiency obtained from the reduction experiments (the row where banseline-1 is located in Table 1) are shown in Table 1 below:

[0133] Table 1

[0134]

[0135] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0136] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0137] The methods of this disclosure may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The order in which the steps of the methods are described is for illustrative purposes only, and the steps of the methods of this disclosure are not limited to the specific order described above unless otherwise specifically stated. Furthermore, in some embodiments, this disclosure may also be implemented as a program recorded on a recording medium, the program including machine-readable instructions for implementing the methods according to this disclosure. Thus, this disclosure also covers recording media storing programs for performing the methods according to this disclosure.

[0138] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A method for optimizing the photoelectric conversion efficiency of a solar cell, comprising: Two-stage experiments, four-stage experiments, and collaborative optimization experiments; The two-stage experiment includes: fixing the printing parameters of the front sub-grid lines of the first battery cell, adjusting the first printing parameters of the printing of the back sub-grid lines of the first battery cell, printing the sub-grid lines on the back of the first battery cell using the adjusted first printing parameters each time, and obtaining the first correspondence between the wet weight of the two-stage slurry of the back sub-grid lines of the first battery cell printed based on each first printing parameter and the photoelectric conversion efficiency of the first battery cell. The four experiments include: fixing the printing parameters of the sub-grid lines on the back of the second battery cell, adjusting the second printing parameters of the printing of the sub-grid lines on the front of the second battery cell, printing the sub-grid lines on the front of the second battery cell using the adjusted second printing parameters each time, and obtaining a second correspondence between the wet weight of the four slurries of the sub-grid lines on the front of the second battery cell printed based on each second printing parameter and the photoelectric conversion efficiency of the second battery cell. The collaborative optimization experiment includes: adjusting the third and fourth printing parameters for printing the back sub-gate lines and front sub-gate lines of the third solar cell based on the wet weight of the second slurry corresponding to the optimal photoelectric conversion efficiency in the first correspondence and the wet weight of the fourth slurry corresponding to the optimal photoelectric conversion efficiency in the second correspondence; and obtaining the wet weight arrays of the second and fourth slurry for the back sub-gate lines and front sub-gate lines of the third solar cell printed based on each third and fourth printing parameter and the third correspondence relationship between the photoelectric conversion efficiency of the third solar cell. The correlation between the wet weight array of the two-stage and four-stage slurry and the photoelectric conversion efficiency is determined based on the third correspondence; wherein, the correlation is used to determine the sub-grid line printing parameters of the solar cell to optimize the photoelectric conversion efficiency of the solar cell.

2. The method according to claim 1, characterized in that, The two experiments specifically include: Step 10: Adjust the current first and second printing parameters, and print sub-grid lines on the back of the first cell according to the adjusted current first and second printing parameters; Step 20: Obtain the wet weight of the second slurry on the back of the first solar cell's sub-grid lines; Step 30: Print sub-grid lines on the front side of the first battery cell according to the current first and fourth printing parameters; Step 40: Obtain the first photoelectric conversion efficiency of the first solar cell, and record the first correspondence between the wet weight of the second slurry on the back of the first solar cell and the first photoelectric conversion efficiency; Step 50: Determine whether the number of experiments in the second experiment meets the first requirement. If the first requirement is not met, fix the current first and fourth printing parameters and return to step 10. If the first requirement is met, end the second experiment.

3. The method according to claim 1, characterized in that, The four experiments specifically include: Step 11: Print sub-grid lines on the back of the second cell according to the current second printing parameters; Step 21: Adjust the current second and fourth printing parameters, and print sub-grid lines on the front side of the second cell according to the adjusted current second and fourth printing parameters; Step 31: Obtain the wet weight of the slurry on the four sides of the sub-grid line on the front side of the second solar cell; Step 41: Obtain the second photoelectric conversion efficiency of the second solar cell, and record the second correspondence between the wet weight of the four slurries on the front side of the second solar cell and the second photoelectric conversion efficiency; Step 51: Determine whether the number of the four experiments meets the second number requirement. If the second number requirement is not met, maintain the current second printing parameters and return to step 11. If the second number requirement is met, end the four experiments.

4. The method according to claim 1, characterized in that, The collaborative optimization experiment specifically includes: Step 12: Select the wet weight of the second slurry corresponding to the optimal photoelectric conversion efficiency from the first correspondence, and select the wet weight of the fourth slurry corresponding to the optimal photoelectric conversion efficiency from the second correspondence; Step 22: Set the current third second-pass printing parameters based on the selected second-pass wet weight of the paste, and set the current third and fourth-pass printing parameters based on the selected fourth-pass wet weight of the paste. Step 32: Based on the current third and second printing parameters, print sub-grid lines on the back of the third cell and obtain the wet weight of the second slurry for the sub-grid lines on the back of the third cell; Step 42: Based on the current third and fourth printing parameters, print sub-grid lines on the front side of the third cell and obtain the wet weight of the four slurries for the sub-grid lines on the front side of the third cell. Step 52: Record the wet weight of the second slurry on the back side of the third cell and the wet weight of the fourth slurry on the front side of the third cell as a wet weight array of the second and fourth slurries; Step 62: Obtain the third photoelectric conversion efficiency of the third solar cell, and record the third correspondence between the wet weight array of the second and fourth slurries and the third photoelectric conversion efficiency; Step 72: Determine whether the number of times the collaborative optimization experiment meets the requirement for the third time. If the requirement for the third time is not met, adjust the current third and second printing parameters and the third and fourth printing parameters, and return to step 32. If the requirement for the third time is met, end the collaborative optimization experiment.

5. The method according to claim 4, characterized in that, The adjustment of the current third and fourth printing parameters includes: Based on the principle of simultaneously reducing / increasing the wet weight of the second and fourth pass slurries by the same amount, the current third and fourth pass printing parameters are adjusted.

6. The method according to any one of claims 1 to 5, characterized in that: The two experiments also include: Obtain the first shaping parameters of the sub-grid lines on the back of the first battery cell, and add the first shaping parameters to the first correspondence; The four experiments also include: Obtain the second shaping parameters of the front sub-gate line of the second battery cell, and add the second shaping parameters to the second correspondence; The collaborative optimization experiment also includes: Obtain the third shaping parameters of the sub-grid lines on the back side of the third battery cell and the fourth shaping parameters of the sub-grid lines on the front side of the third battery cell, and add the third shaping parameters and the fourth shaping parameters to the third correspondence.

7. The method according to any one of claims 1 to 5, characterized in that, The adjustment of the first printing parameters for printing the sub-grid lines on the back of the first battery cell includes: Based on the expected trend of the wet weight change of the second slurry, adjust the first printing parameters for printing the sub-grid lines on the back of the first battery cell. Furthermore, the two experiments also include: If the wet weight of the second layer of paste on the back of the first battery cell printed based on the first printing parameters does not conform to the expected trend of the wet weight of the second layer of paste, the printing component shall be replaced.

8. The method according to any one of claims 1 to 5, characterized in that, The adjustment of the second printing parameters for printing the front sub-gate lines of the second battery cell includes: Based on the expected trend of the wet weight change of the four slurries, adjust the second printing parameters for printing the front sub-gate lines of the second battery cell. Furthermore, the four experiments also include: If the wet weight of the four slurries on the front side of the second battery cell printed based on the second printing parameters does not conform to the expected trend of the wet weight of the four slurries, the printing component shall be replaced.

9. The method according to any one of claims 1 to 5, characterized in that, The adjustment of the third printing parameters for the back sub-grid lines and the fourth printing parameters for the front sub-grid lines of the third battery cell includes: Based on the expected trends in the wet weight of the second and fourth slurries, adjust the third printing parameters for the back sub-grid lines of the third cell and the fourth printing parameters for the front sub-grid lines. Furthermore, the collaborative optimization experiment also includes: If the wet weight of the two slurries on the back side of the third battery cell printed based on the third printing parameters does not conform to the expected trend of the wet weight of the two slurries, and / or if the wet weight of the four slurries on the front side of the third battery cell printed based on the fourth printing parameters does not conform to the expected trend of the wet weight of the four slurries, the printing component shall be replaced.

10. The method according to any one of claims 1-5, characterized in that, The method further includes: Before the two-stage experiment, the four-stage experiment, and the optimized synergistic experiment, the solar cell was screen-printed according to the basic printing parameters, and the basic wet weight values ​​of the two-stage paste, the basic wet weight values ​​of the four-stage paste, and the reference value of photoelectric conversion efficiency were obtained. After the two-stage experiment, the four-stage experiment, and the synergistic optimization experiment, the two-stage printing parameters and the four-stage printing parameters are set according to the basic wet weight values ​​of the two-stage slurry and the four-stage slurry. The solar cell is then screen-printed according to the two-stage printing parameters and the four-stage printing parameters, and the restored wet weight values ​​of the two-stage slurry, the restored wet weight values ​​of the four-stage slurry, and the restored photoelectric conversion efficiency values ​​are obtained. When the deviations of the baseline wet weight values ​​of the second-stage slurry, the baseline wet weight values ​​of the fourth-stage slurry, and the reference values ​​of photoelectric conversion efficiency from the restored wet weight values ​​of the second-stage slurry, the restored wet weight values ​​of the fourth-stage slurry, and the restored values ​​of photoelectric conversion efficiency meet the deviation requirements, the second-stage experiment, the fourth-stage experiment, and the collaborative optimization experiment are considered as valid experiments.

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