Solar cell processing method, solar cell and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a solar cell processing method, a solar cell and a photovoltaic module. The processing method comprises the following steps: performing laser etching on a first region of a substrate, wherein a second region adjacent to the first region is a damaged region; and obtaining the width of the second area. And judging whether the width of the second area is within a preset width range or not. And when the width of the second area is within the range of the preset width, recording the parameters of laser etching as qualified parameters, and processing the battery piece by using the qualified parameters. And when the width of the second area is not in the range of the preset width, adjusting parameters of laser etching, and obtaining a new width of the second area until the obtained width of the second area is in the range of the preset width. Through the design, the damage caused by laser can be quantified, so that the processing technology of the solar cell can be optimized, and the efficiency of the solar cell can be improved.

Description

Technical Field

[0001] This application relates to the field of photovoltaics, and particularly to a processing method for solar cells, a solar cell, and a photovoltaic module. Background Art

[0002] With the development of technology, photovoltaic modules have become commonly used devices, and the solar cells of photovoltaic modules can convert light energy into electrical energy. When processing solar cells, a laser etching step is usually included, and laser etching will cause damage to the solar cells, and the damage will lead to a reduction in the efficiency of the solar cells. Summary of the Invention

[0003] Embodiments of this application provide a processing method for solar cells, a solar cell, and a photovoltaic module, which are used to improve the efficiency of solar cells.

[0004] Embodiments of this application provide a processing method for solar cells, and the processing method includes: Laser etching is performed on a first region of a substrate, and a second region adjacent to the first region is a damaged region; Obtain the width of the second region; Determine whether the width of the second region is within a predetermined width range; When the width of the second region is within the predetermined width range, record the laser etching parameters as qualified parameters, and use the qualified parameters to process the solar cells; When the width of the second region is not within the predetermined width range, adjust the laser etching parameters and perform laser etching, and obtain the width of the new second region until the width of the obtained second region is within the predetermined width range.

[0005] In a possible implementation manner, the step of performing laser etching on a first region of a substrate, where a second region adjacent to the first region is a damaged region, includes: Perform laser etching on the first region of the substrate; Remove the oxide layer of the substrate; Perform wet etching on the substrate to form a textured surface in a region adjacent to the first region, and the region where the textured surface is formed is the second region.

[0006] In a possible implementation manner, before removing the oxide layer of the substrate, the step of performing laser etching on a first region of the substrate, where a second region adjacent to the first region is a damaged region, includes: Perform wet etching on the substrate to remove the polysilicon layer, silicon oxide layer, and part of the crystalline silicon layer of the substrate.

[0007] In a possible implementation, the parameters for laser etching the first region of the substrate are as follows: the wavelength of the laser is 515 nanometers to 532 nanometers, the frequency is 1000 KHz to 1400 KHz, the pulse width is 8 ps to 15 ps, the scanning speed is 3 m / s to 6.5 m / s, and the energy density is 0.1 J / to 1 J / ; The steps for removing the oxide layer of the substrate include: wet etching the substrate with a hydrofluoric acid solution having a mass fraction of 30% to 60%, and the reaction time is 10 seconds to 30 seconds; The steps for wet etching the substrate to remove the polysilicon layer, silicon oxide layer, and part of the single-crystalline silicon layer of the substrate include: wet etching the substrate with a sodium hydroxide solution having a mass fraction of 3% to 8%, the reaction temperature is 60 °C to 85 °C, and the reaction time is 100 seconds to 1000 seconds; The steps for wet etching the substrate to form a textured surface in a region adjacent to the first region, and the region where the textured surface is formed is the second region include: wet etching the substrate with a sodium hydroxide solution having a mass fraction of 2% to 10% and an alkali polishing additive having a mass fraction of 0.1% to 2%, the reaction temperature is 50 °C to 85 °C, and the reaction time is 50 seconds to 300 seconds.

[0008] In a possible implementation, the steps for wet etching the substrate to form a textured surface in a region adjacent to the first region, and the region where the textured surface is formed is the second region include: The wet etching depth of the substrate does not exceed 10 microns.

[0009] In a possible implementation, before determining whether the width of the second region is within a predetermined width range, the processing method of the solar cell further includes: Processing a solar cell to be detected using the same parameters of the laser etching, and detecting the efficiency of the solar cell to be detected; Obtaining the correlation between the energy density of the laser etching, the width of the damaged region, and the efficiency of the solar cell and establishing a model; Obtaining the predicted width of the damaged region according to the energy density of the laser etching through the model, and determining whether the predicted width is within the predetermined width range.

[0010] In a possible implementation, the steps for adjusting the parameters of the laser etching include: adjusting at least one parameter of the wavelength, frequency, pulse width, power, and energy density of the laser.

[0011] The predetermined width does not exceed 3.5 microns.

[0012] In a second aspect of the embodiments of the present application, a solar cell is provided, and the solar cell is processed by the processing method of the solar cell described in any one of the above.

[0013] In a third aspect of the embodiments of the present application, a photovoltaic module is provided, and the photovoltaic module includes the solar cell described above.

[0014] The embodiments of the present application provide a processing method of a solar cell, a solar cell, and a photovoltaic module. The processing method includes: laser etching a first region of a substrate, and a second region adjacent to the first region is a damaged region. Obtain the width of the second region. Determine whether the width of the second region is within a predetermined width range. When the width of the second region is within the predetermined width range, record the parameters of the laser etching as qualified parameters, and process the solar cell using the qualified parameters. When the width of the second region is not within the predetermined width range, adjust the parameters of the laser etching, obtain the new width of the second region, until the obtained width of the second region is within the predetermined width range. The beneficial effect of the embodiments of the present application is to quantify the damage caused by the laser, which is beneficial to optimizing the processing technology of the solar cell and improving the efficiency of the solar cell. Description of the Drawings

[0015] Figure 1 It is a flowchart of the processing method of the solar cell provided by the embodiments of the present application; Figure 2 It is a flowchart of texturing in the second region provided by the embodiments of the present application; Figure 3 It is a flowchart of etching provided by the embodiments of the present application; Figure 4 It is a schematic diagram of the substrate provided by the embodiments of the present application; Figure 5 It is a schematic diagram of the substrate after laser etching provided by the embodiments of the present application; Figure 6 It is a schematic diagram of the substrate after the first alkali etching provided by the embodiments of the present application; Figure 7 It is a schematic diagram of the substrate after acid etching provided by the embodiments of the present application; Figure 8 It is a schematic diagram of the substrate after the second alkali etching provided by the embodiments of the present application; Figure 9 It is an image of the textured surface provided by the embodiments of the present application.

[0016] Reference Signs 1 - Substrate; 2 - First Region; 3 - Second Region; 31 - Modified area; 32 - Re - condensation area; 33 - Matt surface; 4 - Oxide layer; 5 - Polysilicon layer; 6 - Silicon oxide layer; 7 - Crystalline silicon layer. Detailed implementation manners

[0017] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0018] It should be clear that the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts belong to the scope of protection of this application.

[0019] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments, and are not intended to limit this application. The singular forms "a", "the" and "said" used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0020] It should be understood that the term " / and" used herein is only a description of the associated relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0021] As Figure 1 shown, the embodiments of this application provide a processing method for a solar cell, and the processing method for processing a solar cell includes: Step S1: Laser - etch the first region 2 of the substrate 1, and the second region 3 adjacent to the first region 2 is a damaged region; Step S2: Obtain the width of the second region 3; Step S3: Determine whether the width of the second region 3 is within the range of a predetermined width; When the width of the second region 3 is within the range of the predetermined width, record the parameters of the laser etching as qualified parameters, and use the qualified parameters to process the solar cell; When the width of the second region 3 is not within the range of the predetermined width, adjust the parameters of the laser etching and perform laser etching to obtain the new width of the second region 3 until the width of the obtained second region 3 is within the range of the predetermined width.

[0022] Solar cell wafers such as TOPCon cell wafers, perovskite tandem cell wafers, and back-contact cell wafers usually include a laser etching step during the processing. During the processing of different solar cell wafers, the purpose of laser etching is also different. According to different processing requirements, laser etching can be used for laser film opening, removing the passivation layer, optimizing the surface structure, etc. The area usually etched by laser is the first area 2, that is, the processing area. The position adjacent to the first area 2 is the second area 3, and the second area 3 is the damaged area. Heat is generated during the laser etching process, and the heat will transfer to the adjacent area of the first area 2, that is, the heat will transfer to the second area 3 adjacent to the first area 2. The part of the second area 3 close to the first area 2 is the recrystallization zone 32, and the part far from the first area 2 is the modified zone 31. The recrystallization zone 32 is closer to the first area 2 and receives more heat, resulting in a higher temperature in the recrystallization zone 32. The substrate 1 located in the recrystallization zone 32 is heated and melted, and then re-cooled and solidified after the laser etching is completed. The modified zone 31 is farther from the first area 2. Compared with the recrystallization zone 32, the modified zone 31 receives relatively less heat. Usually, the part of the substrate 1 located in the modified zone 31 is heated to cause a change in the lattice structure, resulting in the denaturation of this part of the substrate 1. Compared with other areas of the substrate 1, the properties of the substrate 1 located in the second area 3 change, which will affect the quality of the solar cell wafer during processing, and further result in a lower efficiency of the solar cell wafer. Usually, the damage caused by laser etching is mainly manifested as changes and modifications in the lattice structure, and it is difficult to directly obtain the morphology of the damaged area from the appearance. When optimizing the process parameters of solar cell wafers, there is a lack of basis for controlling the damaged area.

[0023] In the solution provided by the embodiments of the present application, by laser-etching the substrate 1 to obtain the second region 3 and acquiring the width of the second region 3, the size of the damaged region can be obtained. When the width of the second region 3 is larger, the area of the damaged region of the substrate 1 is larger, and the efficiency of the processed solar cell is lower. When the width of the second region 3 is greater than the preset width, the influence of the second region 3 on the efficiency of the solar cell is relatively large, and the efficiency of the obtained solar cell is low. When the width of the second region 3 is within the predetermined width range, the influence of the second region 3 on the efficiency of the solar cell is relatively small, and the efficiency of the obtained solar cell is high. Therefore, when the width of the second region 3 is within the range of the predetermined width, the corresponding laser-etching parameters can be recorded as qualified parameters, and when the width of the second region 3 is not within the range of the predetermined width, the corresponding laser-etching parameters can be recorded as unqualified parameters. When the laser-etching parameters are qualified parameters, the parameters can be used to process the solar cell. When the laser-etching parameters are unqualified parameters, the laser-etching parameters are readjusted, and steps S1 and S2 are repeated to detect the width of the newly obtained second region 3 and determine whether the width of the new second region 3 is within the range of the predetermined width until the adjusted laser-etching parameters are qualified parameters.

[0024] In this way, the damaged region affected by laser etching can be detected, so that the width of the damaged region can be obtained. According to the width of the damaged region, the influence of the damaged region on the efficiency of the solar cell can be judged, and thus the laser-etching parameters can be adjusted and selected to reduce the influence of the damaged region on the efficiency of the solar cell, which is beneficial to improving the efficiency of the solar cell. The size of the damaged region can be quantified by the width of the second region, which is convenient for the operator to obtain the information of the damaged region, so as to more intuitively judge the influence of the damaged region on the solar cell.

[0025] The substrate 1 can be prepared according to the processing flow of the solar cell. Along the thickness direction, the substrate 1 sequentially includes an oxide layer 4, a polysilicon layer 5, a silicon oxide layer 6, and a crystal layer. Among them, according to the different types of the substrate 1, the substrate 1 can be divided into n-type and p-type. The oxide layer 4 of the n-type substrate 1 is usually a phosphosilicate glass (PSG) layer, and the polysilicon layer 5 is an n-type polysilicon. The oxide layer 4 of the p-type substrate 1 is usually a borosilicate glass (BSG) layer, and the polysilicon layer 5 is a p-type polysilicon. The crystalline silicon layer 7 of the substrate 1 is a single crystal silicon.

[0026] In a possible implementation manner, before formally processing the solar cell, multiple substrates 1 are selected, processed with different laser-etching parameters respectively, and qualified parameters are obtained. Then, the qualified parameters are used to process the solar cell to improve the overall quality of the solar cell and better meet the actual use requirements.

[0027] As shown in Figure 2 the following figure, in a possible implementation, step S1 includes: Step S11, performing laser etching on the first region 2 of the substrate 1; Step S12, removing the oxide layer 4 of the substrate 1; Step S13, performing wet etching on the substrate 1 to form a textured surface 33 in the region adjacent to the first region 2, and the region where the textured surface 33 is formed is the second region 3.

[0028] By performing laser etching on the first region 2 of the substrate 1, damage can be formed in the region adjacent to the first region 2. The oxide layer 4 is usually a borosilicate glass layer (BSG layer) or a phosphosilicate glass layer (PSG layer). Removing the surface oxide layer 4 can reduce the influence of the oxide layer 4 on texturing. After removing the oxide layer 4, wet etching is performed on the substrate 1. Since the second region 3 is close to the first region 2, the substrate 1 in the second region 3 melts and re-solidifies after being heated, resulting in the denaturation of the substrate 1 in the re-solidified region 32, and the lattice structure of the substrate 1 in the modified region 31 changes after being heated. Therefore, the properties of the substrate 1 in the second region 3 are different from those of the substrate 1 at other positions, resulting in different wet etching rates. Therefore, during wet etching, the wet etching rates of the modified region 31 and the re-solidified region 32 adjacent to the first region 2 are slower, and a textured surface 33 can be generated. After the wet etching is completed, the region with the textured surface 33 is the second region 3.

[0029] The width of the second region 3 can be obtained by measuring the width of the textured surface 33, and then the width of the damaged region can be obtained. The width of the textured surface 33 can be observed and measured by an optical microscope with a magnification of 20 to 200 times. By adopting the solution provided by the embodiment of the present application, the width of the textured surface 33 can be used as a quantitative index for the damaged region, enabling the operator to more intuitively obtain information about the damaged region, thereby facilitating the judgment of the influence of the damaged region on the efficiency of the solar cell.

[0030] In a possible implementation, before step S12, step S1 includes: S120, performing wet etching on the first region 2 to remove the polysilicon layer 5, the silicon oxide layer 6, and part of the crystalline silicon layer 7 of the first region 2.

[0031] By performing wet etching on the first region 2, a thickness difference can be formed on the surface of the substrate 1. After texturing, there will also be a thickness difference between the position where the textured surface 33 is located and the first region 2. Such a method can make the textured surface 33 easier to observe, reduce the measurement difficulty of the width of the textured surface 33, and is beneficial to improving the measurement accuracy.

[0032] As shown in Figure 3As shown, in a possible implementation, in step S11, the parameters of the laser etching are that the wavelength of the laser is 515 nm to 532 nm, the frequency is 1000 KHz to 1400 KHz, the pulse width is 8 ps to 15 ps, the scanning speed is 3 m / s to 6.5 m / s, and the energy density is 0.1 J / to 1 J / .

[0033] Through such a design, the substrate 1 can be laser-etched to remove the oxide layer 4 and part of the polysilicon layer 5 in the first region 2, so as to simulate the production process of solar cell wafers and form a damaged area on the substrate 1.

[0034] Step S12 includes: wet-etching the substrate 1 with a hydrofluoric acid solution having a mass fraction of 30% to 60%, and the reaction time is 10 seconds to 30 seconds.

[0035] By acid-etching the substrate 1, the oxide layer 4 on the surface of the substrate 1, that is, the borosilicate glass layer and the phosphosilicate glass layer, can be removed. By removing the oxide layer 4, it is beneficial to improve the quality of texturing. At the same time, the presence of the oxide layer 4 will affect the efficiency of texturing, resulting in a decrease in texturing efficiency, an increase in texturing time, and an impact on efficiency.

[0036] Step S120 includes: wet-etching the substrate 1 with a sodium hydroxide solution having a mass fraction of 3% to 8%, the reaction temperature is 60 °C to 85 °C, and the reaction time is 100 seconds to 1000 seconds.

[0037] By alkali-etching the first region 2 of the substrate 1, a thickness difference can be formed between the first region 2 and the second region 3. After texturing, the texture surface 33 can be more easily observed, so that the operator can obtain the width of the texture surface 33, and then obtain the width of the second region 3, that is, the damaged region, in order to quantify the damage caused by laser etching and more intuitively obtain the damage information.

[0038] Step S13 includes: wet-etching the substrate 1 with a sodium hydroxide solution having a mass fraction of 2% to 10% and an alkali-polishing additive having a mass fraction of 0.1% to 2%, the reaction temperature is 50 °C to 85 °C, and the reaction time is 50 seconds to 300 seconds.

[0039] By alkali-etching the substrate 1, since the properties of the substrate 1 in the second region 3 change, the etching rate of the substrate 1 in the second region 3 is different from that of the substrate 1 at other positions, and the surface morphology after etching is also different. Therefore, after alkali-etching, a texture surface 33 can be obtained in the second region 3, and the width of the damaged region can be obtained by obtaining the width of the texture surface 33. Since the texture surface 33 has a relatively obvious difference in morphology from other positions, the width of the damaged region caused by laser etching can be obtained more intuitively.

[0040] In the solution provided by the embodiment of the present application, after the substrate 1 is laser-etched, it is also subjected to three wet etching processes, namely alkali etching, acid etching, and alkali etching. After that, a textured surface 33 can be formed in the damaged area of the laser etching, so as to facilitate the operator to obtain the width of the damaged area. According to the width of the damaged area, the influence caused by the damaged area can be judged. Generally, the width of the damaged area is negatively correlated with the efficiency of the solar cell, that is, the larger the width of the damaged area, the lower the efficiency of the solar cell, and the smaller the width of the damaged area, the higher the efficiency of the solar cell.

[0041] The structure of the substrate 1 is as Figure 4 shown. After laser etching, the structure of the substrate 1 is as Figure 5 shown. The areas adjacent to the first area 2 form a modified area 31 and a recrystallized area 32, and this position corresponds to the second area 3, that is, the damaged area. After the first alkali etching, the structure of the substrate 1 is as Figure 6 shown. By the first alkali etching, a thickness difference is formed between the first area 2 and the second area 3, so as to facilitate the measurement of the textured surface 33 after obtaining the textured surface 33. After acid etching, the structure of the substrate 1 is as Figure 7 shown, and the oxide layer 4 on the surface is removed to reduce the influence of the oxide layer 4 on texturing. After the second alkali etching, the structure of the substrate 1 is as Figure 8 shown. Since the substrate 1 in the second area 3 is denatured, the etching rate at this position is slower than that of other positions, and at the same time, a textured surface 33 can be formed. By measuring the width of the textured surface, the width of the second area 3 can be obtained. The obtained image of the textured surface 33 is as Figure 9 shown, Figure 9 The area indicated by the red dotted line frame in

[0042] In a possible implementation manner, in step S13, the depth of the wet etching of the substrate 1 does not exceed 10 microns.

[0043] When the depth of the wet etching exceeds 10 microns, it is easy to cause the depth of the wet etching to be too deep, and then the etching depth of the second area 3 increases. The damaged area affected by the laser etching may be completely etched, and a textured surface 33 cannot be formed in the second area 3. Therefore, generally, the depth of the wet etching is controlled within 10 microns, so that a thickness difference can be formed between other areas of the substrate 1 and the second area 3, and at the same time, a part of the damaged area affected by the laser etching can be retained and a textured surface 33 can be formed in the damaged area, so as to facilitate the operator to observe.

[0044] In a possible implementation manner, before step S3, the processing method may further include: S30. Process the solar cell to be detected using the same laser etching parameters, and detect the efficiency of the solar cell to be detected. Obtain the correlation between the energy density of laser etching, the width of the damaged area, and the efficiency of the solar cell, and establish a model. According to the model, obtain the predicted width of the damaged area based on the energy density of laser etching, and determine whether the predicted width is within the predetermined width range.

[0045] Through the solution provided by the embodiments of the present application, a model can be established among the energy density of the laser, the width of the second region 3, and the efficiency of the solar cell. The model can be used to predict the efficiency of the solar cell, thereby determining the impact of the damaged area of laser etching on the efficiency of the solar cell. Using this model to adjust the process parameters of laser etching, reducing the width of the second region 3, which is beneficial to optimizing the production process of solar cells, improving the efficiency of solar cells, and reducing production costs.

[0046] The relationship between the energy density and the width of the damaged area is: W = 66.67E - 12.31, where E is in the range of [0.237, 0.267]. Here, W is the width of the damaged area and E is the energy density. The relationship between the width of the damaged area and the efficiency of the solar cell is: eta = -0.0795W + 27.13, where eta is the efficiency of the solar cell and W is the width of the damaged area.

[0047] When processing solar cells, the relationship between the energy density and the width of the damaged area and the relationship between the width of the damaged area and the efficiency of the solar cell can be used to calculate and predict the efficiency of the solar cell. Predict the width of the damaged area and the efficiency of the solar cell through the energy density of the laser, so as to predict the quality of the processed solar cell and whether the solar cell meets the requirements.

[0048] In a possible implementation, the step of adjusting the parameters of laser etching includes: adjusting at least one of the wavelength, frequency, pulse width, power, and energy density of the laser.

[0049] Generally, the shorter the wavelength of the laser, the higher the frequency, the lower the power, the shorter the pulse width, and the lower the energy density, the smaller the damage caused by laser etching. When adjusting, by adjusting a single parameter, the overall parameters of the laser can be adjusted synchronously.

[0050] Generally, the frequency and power of the laser both affect the energy density and there is a certain correlation. To better reduce damage, the power can be reduced while increasing the frequency to facilitate reducing the energy density of the laser, thereby reducing damage.

[0051] By adjusting the parameters of laser etching, the damaged area formed by laser etching on the substrate 1 can be changed, thereby changing the influence of the damaged area on the solar cell.

[0052] In a possible implementation manner, the predetermined width of the second region 3 does not exceed 3.5 micrometers. When the width of the second region 3 is less than 3.5 micrometers, the damage caused by laser etching has a relatively small impact on the efficiency of the solar cell, and the laser etching parameters can be qualified parameters.

[0053] According to the type of the solar cell and the requirements for quality, the value of the predetermined width can be adjusted according to needs, and the predetermined width can be 0.5 micrometers, 1.0 micrometers, 1.5 micrometers, 2.0 micrometers, 2.5 micrometers, 3.0 micrometers, 3.5 micrometers, etc.

[0054] As shown in Table 1, the embodiments of the present application provide the experimental data of the experimental group and the control group. The experimental process is as follows: Control group: Prepare an N-type crystalline silicon substrate, perform standard RCA cleaning on the crystalline silicon substrate, deposit a tunneling oxide layer with a thickness of 1.5 nanometers on the surface of the substrate by LPCVD, and deposit an amorphous silicon layer with a thickness of 200 nanometers on the surface of the tunneling oxide layer by LPCVD. Perform high-temperature annealing in LPCVD, and at the same time dope boron atoms in the amorphous silicon at a temperature of 900 °C for 60 minutes to crystallize the amorphous silicon layer into a polycrystalline silicon layer 5. At the same time, form a 50-nanometer BSG layer on the surface of the polycrystalline silicon layer 5 to obtain the substrate 1 of the control group. Perform laser etching, the first alkali etching, acid etching, and the second alkali etching on the substrate 1 in sequence. The laser etching parameters are: wavelength: 532 nm, frequency: 1200 KHz, pulse width: 10 ps, scanning speed: 6.5 m / s, single-pulse energy density: 0.267 J / cm². The parameters of the first alkali etching are: 4 wt% NaOH solution, 68 °C, 600 s. The parameters of the acid etching are: 49 wt% HF solution, room temperature, 15 s. The parameters of the second alkali etching are: 6 wt% NaOH solution + alkali polishing additive, 78 °C, 180 s. Measure the width of the textured surface 33 with an optical microscope, and the width of the textured surface 33 is obtained as 5.5 micrometers. The other parameters of the solar cells in the control group are shown in Table 1.

[0055] Experimental group: Prepare an N-type crystalline silicon substrate, perform standard RCA cleaning on the crystalline silicon substrate, and deposit a tunneling oxide layer with a thickness of 1.5 nm on the substrate surface by LPCVD. Deposit an amorphous silicon layer with a thickness of 200 nm on the surface of the tunneling oxide layer by LPCVD. Perform high-temperature annealing in LPCVD, and simultaneously dope boron atoms into the amorphous silicon at a temperature of 900 °C for 60 minutes to crystallize the amorphous silicon layer into a polycrystalline silicon layer 5. At the same time, form a 50-nm BSG layer on the surface of the polycrystalline silicon to obtain the substrate 1 of the experimental group. Then, perform laser etching, the first alkali etching, acid etching, and the second alkali etching on the substrate 1 in sequence. The parameters of laser etching are: wavelength: 532 nm, frequency: 1200 KHz, pulse width: 10 ps, scanning speed: 6.5 m / s, single-pulse energy density: 0.237 J / cm². The parameters of the first alkali etching are 4 wt% NaOH solution, 68 °C, 600 s. The parameters of acid etching are: 49 wt% HF solution, room temperature, 15 s. The parameters of the second alkali etching are: 6 wt% NaOH solution + alkali polishing additive, 78 °C, 180 s. Finally, use an optical microscope to measure the width of the textured surface 33 to be 3.5 microns.

[0056]

[0057] Table 1 The manufacturing processes of the substrates 1 of the experimental group and the control group are the same, the parameters of the first alkali etching are the same, the parameters of acid etching are the same, and the parameters of the second alkali etching are the same. There are differences in the energy density of laser etching, and the other parameters are the same. The laser energy density of the experimental group decreased from 0.267 J / cm² to 0.237 J / cm² compared with the control group, and the width of the textured surface 33 of the experimental group decreased from 5.5 microns to 3.5 microns compared with the width of the textured surface 33 of the control group. By detecting the back-contact solar cell wafers processed with the corresponding laser etching parameters, the parameters of the photoelectric conversion efficiency (Eta), open-circuit voltage (Voc), short-circuit current (Isc), and fill factor (FF) of the solar cell wafers are shown in Table 1. From the data in Table 1, it can be known that the textured surface 33 of the experimental group is smaller than that of the control group. At the same time, compared with the control group, the photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and fill factor of the experimental group are all improved.

[0058] Combined with the data in Table 1, it can be known that reducing the width of the textured surface 33 is beneficial to improving the photoelectric conversion efficiency of the solar cell wafer and the overall performance of the solar cell wafer. At the same time, according to the experimental results, by reducing the laser energy density, the width of the textured surface 33 can be reduced, which is beneficial to improving the quality of the solar cell wafer. According to the data in Table 1, for every 1-μm reduction in the width of the textured surface, the photoelectric conversion efficiency can be increased by approximately 0.08%.

[0059] Based on the data in Table 1, all the parameter indicators of the solar cell wafers in the experimental group meet the usage requirements. At the same time, since the smaller the width of the textured surface 33, the better the overall performance of the solar cell wafer. Therefore, when the width of the textured surface 33 is less than 3.5 microns, the overall performance of the solar cell wafer will be better than that of the solar cell wafers in the experimental group in Table 1. Therefore, when the width of the textured surface 33 does not exceed 3.5 microns, it can be considered that the damaged area caused by laser etching has less impact on the performance of the solar cell wafer, and the obtained solar cell meets the usage requirements.

[0060] The embodiment of the present application also provides a solar cell wafer, and the solar cell wafer can be processed by the processing method of the solar cell wafer involved in any of the above embodiments. The solar cell wafer can be a back contact cell wafer, a perovskite tandem cell wafer, a TOPCon cell wafer, etc.

[0061] The embodiment of the present application also provides a photovoltaic module, and the photovoltaic module includes the solar cell wafer involved in any of the above embodiments.

[0062] The photovoltaic module may further include structures such as a first cover plate, a second cover plate, a first encapsulant film, and a second encapsulant film. Multiple solar cell wafers are electrically connected to form a solar cell string, and multiple solar cell strings are electrically connected to form a solar cell array. Along the thickness direction of the photovoltaic module, the first encapsulant film and the second encapsulant film are located on opposite sides of the solar cell array. The first cover plate is located on the side of the first encapsulant film away from the solar cell array, and the second cover plate is located on the side of the second encapsulant film away from the solar cell array. The first cover plate and the second cover plate are located on the surface of the photovoltaic module and can play a protective role for the photovoltaic module. The first encapsulant film and the second encapsulant film can play a buffering role to reduce the possibility of the solar cell wafer cracking during lamination and when being collided, thereby being beneficial to improving the service life of the photovoltaic module.

[0063] Adjacent solar cell wafers can be connected by soldering tapes. The sub - grids of the solar cell wafer are used to collect the generated photo - generated current, and the main grids or connection lines are used to collect the current of the sub - grids. The soldering tapes are connected to the main grids or connection lines to be able to lead out the current.

[0064] In a possible implementation manner, adjacent solar cell wafers can also be connected using conductive adhesives. The conductive adhesive has good electrical conductivity and adhesiveness. The conductive adhesive is coated on the electrodes of the cell wafers, and then through pressing and curing, a conductive path can be formed to achieve electrical connection. Connecting through the conductive adhesive can reduce the influence of thermal stress on the solar cell wafers during the connection process and the possibility of mechanical damage, which is beneficial to improving the reliability and stability of the photovoltaic module. In the actual production process, soldering tapes and conductive adhesives can be combined for use to save costs and improve reliability.

[0065] The first cover plate and the second cover plate have high structural strength, providing a certain mechanical strength and rigidity for the photovoltaic module to protect the encapsulant, solar cells, etc. inside the photovoltaic module, reducing the impact of environmental factors such as rain, sand, and dust on the photovoltaic module, and reducing the possibility of the photovoltaic module being corroded, worn, and aged, thus helping to extend the service life of the photovoltaic module.

[0066] When one side of the photovoltaic module is the light-receiving side and the other side is the backlight side, the first cover plate is located on the light-receiving side and the second cover plate is located on the backlight side. The material of the first cover plate is a light-transmitting material, and the material of the second cover plate is a reflective material or a reflective layer is provided. Light can pass through the first cover plate and the first encapsulant to reach the solar cells and be absorbed by the solar cells to generate photocurrent. The light not absorbed by the solar cells can be reflected by the second cover plate after passing through the second encapsulant, so that the light can be transmitted to the solar cells again, enabling the solar cells to absorb the light again, thereby improving the light absorption efficiency of the solar cells and further improving the efficiency of the solar cells.

[0067] When both sides of the photovoltaic module are light-receiving sides, the materials of the first cover plate and the second cover plate are both light-transmitting materials. Such a design can help increase the light-receiving area of the photovoltaic module, thus helping to improve the efficiency.

[0068] The material of the cover plate can be tempered glass, etc. It has good light transmittance while having good strength. When tempered glass is used as the second cover plate, reflection can be achieved by setting a reflective film, a reflective coating, etc. on the surface of the tempered glass to improve the efficiency.

[0069] The first encapsulant and the second encapsulant can be EVA encapsulant, POE encapsulant, EPE encapsulant (EVA-POE-EVA co-extruded encapsulant), etc. The encapsulant is located between the cover plate and the solar cells and can play a role in bonding and fixing, helping the various components of the photovoltaic module to form a whole and reducing the possibility of delamination and detachment during the use of the photovoltaic module. The encapsulant can also play a sealing role, reducing the possibility of external water vapor, oxygen and other substances entering the interior of the photovoltaic module, thereby reducing the possibility of the solar cells and other components being corroded and oxidized, and being beneficial to extending the service life and reliability of the photovoltaic module.

[0070] The encapsulant film can also refract and scatter light to some extent, enabling the light to propagate and be utilized better inside the component, which is conducive to improving the light absorption efficiency of the solar cell and the efficiency of the photovoltaic module, and better meeting the actual usage requirements. The solar cell provided by the embodiment of the present application can be a back-contact cell, and the positive and negative electrodes of the back-contact cell are both arranged on the back of the solar cell, that is, on the light-shielded side of the back-contact cell. Such a design can reduce the occlusion of the light-receiving side by the grid lines, which is conducive to increasing the light-receiving area of the solar cell, and thus conducive to improving the photoelectric conversion efficiency of the solar cell. At the same time, since the electrodes are concentrated on the same side of the solar cell, when collecting the current, the current transmission path is shorter, which is conducive to reducing the loss during the current transmission process, and can improve the fill factor and conversion efficiency of the cell, better meeting the actual usage requirements. By arranging the electrodes on the light-shielded side of the solar cell, the possibility of the electrodes being corroded and damaged in outdoor environments and the like can be reduced. By arranging the electrodes on the light-shielded side, the influence of light and ultraviolet rays on the electrodes can be reduced, the aging rate of the electrodes and the decline of performance can be reduced, which is conducive to extending the service life of the solar cell and improving the reliability of the solar cell. There are usually no electrode grid lines on the front of the back-contact cell. Therefore, the possibility of stress concentration problems caused by differences in thermal expansion coefficients can be reduced, and thus the possibility of cracking and breakage of the solar cell during use can be reduced.

[0071] The embodiment of the present application provides a processing method of a solar cell, the solar cell and a photovoltaic module. The processing method includes: laser-etching a first region 2 of a substrate 1, and a second region 3 adjacent to the first region 2 is a damaged region. Obtain the width of the second region 3. Determine whether the width of the second region 3 is within a predetermined width range. When the width of the second region 3 is within the predetermined width range, record the parameters of the laser etching as qualified parameters, and use the qualified parameters to process the cell. When the width of the second region 3 is not within the predetermined width range, adjust the parameters of the laser etching, obtain the new width of the second region 3, until the obtained width of the second region 3 is within the predetermined width range. Through such a design, the damage caused by the laser can be quantified, which is conducive to optimizing the processing technology of the solar cell and improving the efficiency of the solar cell.

Claims

1. A method for processing a solar cell, characterized in that: The processing method comprises: Laser etching is performed on a first area (2) of a substrate (1), wherein a second area (3) adjacent to the first area (2) is a damaged area; Obtaining the width of the second area (3); Determining whether the width of the second area (3) is within a predetermined width range; When the width of the second region (3) is within a predetermined width range, recording the laser etching parameters as qualified parameters, and processing the battery cell using the qualified parameters; When the width of the second region (3) is not within the range of the predetermined width, the laser etching parameters are adjusted and laser etching is performed to obtain a new width of the second region (3) until the width of the second region (3) is within the range of the predetermined width.

2. The method for processing a solar cell according to claim 1, characterized in that: The step of laser etching a first area (2) of a substrate (1), wherein a second area (3) adjacent to the first area (2) is a damaged area, comprises: Laser etching the first area (2) of the substrate (1); Removing the oxide layer (4) of the substrate (1); The substrate (1) is wet-etched to form a velvet surface (33) in a region adjacent to the first region (2), and the region where the velvet surface (33) is formed is the second region (3).

3. The method for processing a solar cell according to claim 2, characterized in that: Before removing the oxide layer (4) of the substrate (1), the step of laser etching the first area (2) of the substrate (1), wherein the second area (3) adjacent to the first area (2) is a damaged area, comprises: The substrate (1) is wet-etched to remove the polysilicon layer (5), the silicon oxide layer (6) and a portion of the crystalline silicon layer (7) of the substrate (1).

4. The method for processing a solar cell according to claim 2, characterized in that: The parameters for laser etching the first area (2) of the substrate (1) are: a laser wavelength of 515 nanometers to 532 nanometers, a frequency of 1000 kHz to 1400 kHz, a pulse width of 8 ps to 15 ps, a scanning speed of 3 m / s to 6.5 m / s, and an energy density of 0.1 J / To 1J / ; The step of removing the oxide layer (4) of the substrate (1) comprises: using a hydrofluoric acid solution with a mass fraction of 30% to 60% to wet-etch the substrate (1), with a reaction time of 10 seconds to 30 seconds; The step of wet-etching the substrate (1) to remove the polysilicon layer (5), the silicon oxide layer (6) and part of the crystalline silicon layer (7) of the substrate (1) comprises: wet-etching the substrate (1) using a sodium hydroxide solution having a mass fraction of 3% to 8%, at a reaction temperature of 60° C. to 85° C. and a reaction time of 100 seconds to 1000 seconds; The step of wet-etching the substrate (1) to form a velvet surface (33) in an area adjacent to the first area (2), wherein the area where the velvet surface (33) is formed is the second area (3) comprises: wet-etching the substrate (1) using a sodium hydroxide solution having a mass fraction of 2% to 10% and an alkali polishing additive having a mass fraction of 0.1% to 2%, the reaction temperature being 50° C. to 85° C. and the reaction time being 50 seconds to 300 seconds.

5. The method for processing a solar cell according to claim 2, characterized in that: The step of wet-etching the substrate (1) to form a velvet surface (33) in a region adjacent to the first region (2), wherein the region where the velvet surface (33) is formed is the second region (3) comprises: The wet etching depth of the substrate (1) does not exceed 10 micrometers.

6. The method for processing a solar cell according to any one of claims 1 to 5, characterized in that: Before determining whether the width of the second region (3) is within a predetermined width range, the solar cell processing method further comprises: Processing the solar cell to be tested using the same laser etching parameters, and testing the efficiency of the solar cell to be tested; Obtaining the relationship between the energy density of the laser etching, the width of the damaged area and the efficiency of the solar cell and establishing a model; The predicted width of the damaged area is obtained according to the energy density of laser etching through the model, and it is determined whether the predicted width is within the predetermined width range.

7. The method for processing a solar cell according to any one of claims 1 to 5, characterized in that: The step of adjusting the parameters of laser etching includes: adjusting at least one parameter of the wavelength, frequency, pulse width, power and energy density of the laser.

8. The method for processing a solar cell according to any one of claims 1 to 5, characterized in that: The predetermined width does not exceed 3.5 microns.

9. A solar cell, characterized in that: The solar cell is processed by the solar cell processing method according to any one of claims 1 to 8.

10. A photovoltaic module, characterized in that: The photovoltaic module comprises the solar cell sheet according to claim 9.

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