Method for repairing power attenuation of solar cell module

Abstract

The invention belongs to the technical field of solar energy, and provides a method for repairing power attenuation of a solar cell module, which comprises the following steps of: 1, preparing a solar cell subjected to laser-assisted sintering treatment; step 2, preparing a corresponding JSIM cell assembly by using the solar cell subjected to laser-assisted sintering treatment; 3, applying a negative bias voltage to the JSIM battery assembly, and scanning the surface of the JSIM battery assembly by using laser so as to perform power attenuation repair on the JSIM battery assembly; in the step 3, the negative bias voltage applied to the JSIM battery assembly is controlled to be within the range of-400V to-1000V, and the laser power is 50-300W. According to the method, the power loss of the JSIM battery assembly can be recovered, the power of the JSIM battery assembly is improved, the photoelectric conversion efficiency of the JSIM battery assembly is further improved, the structure of the JSIM battery assembly cannot be damaged, and repairing is rapid and stable.

Description

Technical Field

[0001] The invention relates to the technical field of solar energy, and in particular to a method for repairing power attenuation of a solar cell assembly. Background Art

[0002] The existing laser-assisted sintering technology (such as Jolywood Special Injected Metallization, JSIM technology) uses a combination of laser and bias to make the electrodes in the pre-sintered solar cells reach extremely high temperatures in a very short time, thereby improving the contact performance of the electrodes. Compared with the traditional one-step sintering method, pre-sintering combined with JSIM technology can reduce the damage to the passivation layer of the solar cell and enhance the contact performance of the electrode; but it also brings instability to the contact structure of the solar cell. At present, researchers have found that solar cells (referred to as JSIM cells) that have introduced laser-assisted sintering technology do not experience power attenuation before the preparation of solar cell modules. However, after the JSIM battery module is manufactured, a large power attenuation will occur, and the CTM (the percentage of the module output power to the total power of the cell) will decrease. According to research, this power attenuation is mainly caused by the unstable contact structure formed by the JSIM battery being sensitive to temperature. Therefore, in the subsequent JSIM battery module manufacturing process or the use of the JSIM battery module, when a high-temperature process or high-temperature environment occurs, the JSIM battery module will experience power attenuation, which we call thermal attenuation of the JSIM battery module. For example, the process temperature of heating and lamination during the manufacturing process of the JSIM battery module, the temperature at which hot spots appear on the solar cell module, or the temperature at which the solar cell module is exposed to the sun when used outdoors will cause the JSIM battery module to experience power attenuation.

[0003] Since the process time of laser-assisted sintering (JSIM) is very short (for example, the action time of a laser spot is only 10ns-10μs), the initial passivation contact structure formed by the JSIM battery forms an unstable silver-silicon alloy, and there is also some unstable hydrogen. During the subsequent production or use of JSIM battery components, under the action of heat, the unstable hydrogen is easily broken into free hydrogen, and a large number of interface states, i.e., defect states, are also generated. Therefore, the subsequent JSIM battery opening voltage is reduced, and the unstable silver-silicon alloy is transformed into a stable state. The connected dendrites are deformed, the conduction path is broken, the series resistance is increased, the FF is reduced, and the photoelectric conversion efficiency is greatly reduced, which in turn causes the power attenuation of the JSIM battery component and a low CTM.

[0004] However, there is currently no relevant solution to the thermal attenuation problem of the JSIM battery assembly. Moreover, the solar cell assembly formed by the conventional passivated contact solar cell mentioned in CN113571605B will not experience the thermal attenuation of the JSIM battery assembly. This is because the conventional passivated contact solar cell is not processed using the JSIM technology, and still uses high-temperature sintering to form the ohmic contact of the electrode. This method of high-temperature sintering to form the electrode ohmic contact is a slow process; and the time for the JSIM technology to form the electrode ohmic contact is very short, so the JSIM battery will form unstable hydrogen or other unstable state structures or other implicit defects that are different from the slow ohmic contact, resulting in no power attenuation in the JSIM battery at the moment, but power attenuation after the JSIM battery assembly is completed. Therefore, a method for eliminating hydrogen-induced attenuation of passivated contact solar cells, such as that provided by CN113571605B, is difficult to achieve an ideal repair effect on the power attenuation of the JSIM battery assembly.

[0005] In addition, for the attenuation problem of conventional solar cell modules, WO2023048637A2 proposes a method for repairing light-induced attenuation, that is, using a lighting module at a certain temperature to scan the surface of the solar cell module for repair. However, solar cell modules cannot withstand excessively high temperatures, because excessively high temperatures can easily cause degradation and spontaneous combustion of the adhesive film, and the JSIM battery itself is more sensitive to temperature. Therefore, this repair method is difficult to work on the repair of thermally attenuated JSIM battery modules. Therefore, it is urgent to propose a method specifically for repairing power attenuation of JSIM battery modules. Summary of the invention

[0006] The purpose of the present invention is to provide a method for repairing the power attenuation of a solar cell module in view of the deficiencies in the prior art. The method can repair the power loss of a JSIM cell module that has thermally attenuated after the application of the JSIM technology, thereby increasing the power of the JSIM cell module.

[0007] Based on this, the present invention discloses a method for repairing power attenuation of a solar cell module, comprising the following steps:

[0008] Step 1, preparing a solar cell that has been subjected to laser-assisted sintering;

[0009] Step 2, using the solar cells processed by laser-assisted sintering to prepare the corresponding JSIM battery components;

[0010] Step 3, applying a negative bias voltage to the JSIM battery assembly, and scanning the surface of the JSIM battery assembly with a laser to repair the power attenuation of the JSIM battery assembly;

[0011] In step 3, the negative bias voltage applied to the JSIM battery assembly is controlled within the range of -400V to -1000V, and the laser power is 50-300W.

[0012] Preferably, in step 3, the front side of the JSIM battery assembly is scanned using the laser.

[0013] Further preferably, in step 3, the time for repairing the JSIM battery assembly is controlled within the range of 5-300s; the specific time for the repairing process may vary depending on the laser spot size and laser frequency.

[0014] Further preferably, in step 3, the spot size of the laser is 50-500 μm, the laser wavelength is 532 nm, 1030 nm or 1064 nm, and the laser scanning method is to perform full-surface scanning or line scanning on the JSIM battery assembly.

[0015] Preferably, the JSIM battery assembly is provided with a junction box for conducting its current to the outside;

[0016] In step 3, a negative bias voltage is applied to the JSIM battery assembly using the interface of the junction box.

[0017] Preferably, in step 1, the solar cell is a TOPCon cell (a solar cell with tunneling oxide passivation contact using an N-type silicon wafer as a substrate).

[0018] Further preferably, the step 1 specifically comprises the following steps:

[0019] Step 11, the silicon wafer is sequentially cleaned and textured, front boron diffusion doping is performed to prepare the emitter, pickled, back surface alkaline polished, back surface passivation contact structure is deposited, annealed, cleaned, front and back passivation films are deposited, screen printed and sintered to form front and back electrodes, so as to obtain a TOPCon battery;

[0020] Step 12: Perform laser-assisted sintering on the front side of the TOPCon battery in step 11 to obtain a TOPCon battery that has been subjected to laser-assisted sintering.

[0021] Preferably, step 2 specifically includes the following steps:

[0022] Step 21, slicing the solar cell processed by laser-assisted sintering to obtain a plurality of sliced ​​cells;

[0023] Step 22, welding a plurality of sliced ​​batteries in series to obtain a battery string;

[0024] Step 23, heating and laminating the photovoltaic front panel, the first packaging film, the battery string, the second packaging film and the photovoltaic back panel stacked in sequence from top to bottom to obtain a photovoltaic laminate;

[0025] Step 24: Install the side of the photovoltaic laminate in the photovoltaic frame and install the junction box to obtain the JSIM battery assembly.

[0026] Further preferably, before step 22, a step of passivating the cut edges of the sliced ​​cells is also included.

[0027] Further preferably, in step 24, a sealant is injected to encapsulate the side of the photovoltaic laminate in the photovoltaic frame, and the sealant is heated and cured to obtain the JSIM battery assembly.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] The introduction of laser-assisted sintering technology has been found to greatly improve the contact performance of solar cells. However, after the application of laser-assisted sintering technology, JSIM battery components are prone to unstable performance, power attenuation, CTM reduction and other undesirable phenomena during the production and use process. In particular, during the production process of JSIM battery components, several temperature treatment processes (such as serial welding process, heating lamination process, etc.) are required, which pose challenges to the stability of the power and other aspects of the JSIM battery components.

[0030] Based on this, a method for repairing power attenuation of a solar cell module of the present invention directly performs power attenuation repair on the prepared JSIM battery module (i.e., thermal attenuation repair of the JSIM battery module) without changing the preparation process of the existing JSIM battery module. A negative bias voltage in the range of -400V to -1000V is applied using the existing junction box interface of the JSIM battery module, and a 50-300W laser is used to quickly scan the surface of the JSIM battery module. This can not only restore the power loss of the JSIM battery module and increase the power of the JSIM battery module, thereby improving the photoelectric conversion efficiency of the JSIM battery module, but also will not damage the structure of the JSIM battery module. The repair is fast and stable. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with specific implementation methods.

[0032] Example

[0033] A method for repairing power attenuation of a solar cell assembly according to this embodiment includes the following steps:

[0034] Step 1: Prepare a solar cell that has been subjected to laser-assisted sintering. The solar cell in step 1 is preferably a TOPCon cell.

[0035] Step 1 specifically includes the following steps:

[0036] Step 11, the silicon wafer is cleaned and textured, the front side is doped with boron to prepare the emitter, pickled, the back surface is alkaline polished, the back side is deposited with a passivation contact structure, annealed, cleaned, the front and back side passivation films are deposited, screen printed and sintered to form the front and back electrodes to obtain a TOPCon battery.

[0037] Step 12: Perform laser-assisted sintering on the front side of the TOPCon battery in step 11 to obtain a TOPCon battery (ie, a JSIM battery) that has been subjected to laser-assisted sintering.

[0038] Step 2: Use solar cells that have been subjected to laser-assisted sintering to prepare corresponding solar cell modules (ie, JSIM cell modules).

[0039] Step 2 specifically includes the following steps:

[0040] Step 21: Slice the solar cells that have been subjected to the laser-assisted sintering process to obtain a plurality of sliced ​​cells.

[0041] Step 22: weld several sliced ​​batteries in series to obtain a battery string.

[0042] Step 23, heating and laminating the photovoltaic front panel, the first packaging film, the battery string, the second packaging film and the photovoltaic back panel stacked in sequence from top to bottom to obtain a photovoltaic laminate.

[0043] Step 24: Install the side of the photovoltaic laminate in the photovoltaic frame and install the junction box to obtain the JSIM battery assembly.

[0044] In step 21, the sliced ​​cells are half-cells, 1 / 3-cells or more cells. The slicing process is used to reduce the series resistance of the solar cell module, thereby helping to increase the output power of the solar cell module.

[0045] After obtaining the sliced ​​battery and before performing the string welding process in step 22, a step of passivating the cut edges of the sliced ​​battery is also included to improve the damage of the cut edges of the sliced ​​battery.

[0046] In step 24, a sealant is injected to encapsulate the side of the photovoltaic laminate in the photovoltaic frame, and the sealant is heated and cured to obtain a JSIM battery assembly. The JSIM battery assembly draws the current of the battery string to the external junction box through the welding strip and the bus bar, and then the interface of the junction box is electrically connected to the external electrical device to realize the power supply of the JSIM battery assembly to the external electrical device.

[0047] It should be noted that the preparation processes of the JSIM battery and its components in the above steps 1 and 2 are based on the prior art and will not be described in detail here.

[0048] Step 3: Use the junction box interface to apply a negative bias voltage to the JSIM battery assembly, and use a laser to scan the front of the JSIM battery assembly to complete the power attenuation repair of the JSIM battery assembly.

[0049] During the preparation of the JSIM battery assembly in step 2, the heating processes such as serial welding and lamination make the unstable hydrogen in the JSIM battery in a free state after the bond is broken, and a large number of defect states are also formed at this time. Therefore, after the JSIM battery assembly is completed, a specific negative bias is applied to the JSIM battery assembly in a power attenuation state, and a specific laser is used to scan the front of the JSIM battery assembly; so that the free hydrogen or the hydrogen that has been stably bonded in the JSIM battery is activated under the action of the specific negative bias and laser irradiation, so that under the heat generated by the high current density and the regulation of the specific laser, the valence state of hydrogen will be reset to the initial state (that is, the initial state when the JSIM battery is prepared, and the silver-silicon alloy can also re-form the initial conductive structure under the action of the laser. The reset of this initial state is closely related to the laser power and negative bias used for the specific repair in step 3), thereby realizing the repair of the power-attenuated JSIM battery assembly to improve the power of the JSIM battery assembly.

[0050] Furthermore, the power attenuation of the JSIM battery assembly mainly occurs on the front side of the JSIM battery assembly which is sensitive to temperature. Therefore, in step 3, it is preferred to perform laser scanning on the front side of the JSIM battery assembly.

[0051] Furthermore, if the back of the TOPCon cell is also processed by the JSIM process, and an unstable contact structure is formed on the back of the cell, resulting in thermal attenuation of the module power, the repair method can also be applied to the back of the module. In this case, a combination of positive bias and back laser scanning is required for repair. If the module adopts a single-glass packaging solution, the obstruction of the backplane material to the laser must also be considered.

[0052] In step 3, the laser power is 50-300W; the laser wavelength includes but is not limited to 532nm, 1030nm or 1064nm; the laser spot size can be adjusted according to the actual laser scanning speed and laser power, and the laser spot size is specifically 50-500μm; the laser scanning method includes but is not limited to scanning the entire surface or line scanning of the front side of the JSIM battery assembly; the laser includes but is not limited to continuous laser or pulsed laser.

[0053] In step 3, the negative bias voltage applied to each JSIM cell (i.e., the solar cell processed by laser assisted sintering in step 1) used in the JSIM cell assembly is controlled within the range of -15 V to -25 V. For a JSIM cell assembly with 54, 60, 72 or 78 cells, the negative bias voltage required is within the range of -400 V to -1000 V.

[0054] It should be noted that the repair in step 3 uses bias to guide the directional movement of carriers inside the JSIM battery. When a negative bias (i.e., reverse bias voltage) is applied to the JSIM battery assembly, the free carriers generated are separated by the voltage, and the electrons move toward the N region, which is conducive to the diffusion of silver into silicon to form a silver-silicon alloy. If a positive bias is applied to the JSIM battery assembly, the electrons move toward the P region and silver diffuses toward the electrode, which is not conducive to the formation of the silver-silicon alloy and cannot repair or improve the power attenuation problem of the JSIM battery assembly.

[0055] In step 3, the method for repairing the power attenuation of the solar cell module requires a high negative bias voltage and an extremely short repair treatment time; specifically, the repair treatment time of the JSIM battery module is controlled within the range of 5-300s depending on the version, and the repair treatment time for each JSIM battery (i.e., the solar cell treated with laser-assisted sintering in step 1) is controlled within 1s.

[0056] Performance Testing

[0057] 1. Table 1 below shows the power change data of the JSIM battery assembly before and after the power attenuation repair step (i.e., step 3). Among them, BL is a JSIM battery assembly without power attenuation repair, samples 1 and 2 are JSIM battery assemblies with added power attenuation repair steps, and the three JSIM battery assemblies are all single JSIM battery assemblies, and each sample is tested twice. The test data of BL-1 and BL-2 are only the JSIM battery assemblies tested together as a reference group in the initial test and the retest; the difference between the two tests is the test error (the difference in the two test results caused by various factors such as the test machine, the test environment, or the test time).

[0058] The battery string in the JSIM battery module samples (sample 1, sample 2) used in the test in Table 1 is formed by connecting two half-cell batteries (corresponding to a complete JSIM battery) in series; the negative bias voltage applied in step 3 is -18V, the laser power is 100W, the laser wavelength is 1030nm, the laser spot size is 200μm, and the laser scanning method is to scan the entire front surface of the JSIM battery module sample.

[0059] Table 1

[0060]

[0061]

[0062] 2. Table 2 shows the performance test data of the repaired JSIM battery obtained by applying different negative bias voltages (voltages exceeding the negative bias voltage range of the embodiment, such as -32V, -10V, and voltages within the negative bias voltage range of the embodiment, such as -17V) to the JSIM battery in step 3. The laser parameters used in step 3 in Table 2 refer to the laser parameters in Table 1.

[0063] Table 2

[0064] Negative bias project Jsc Voc FF Eta R Rshunt IRev1 -32V SY-4.2-SP6 34.331 715.526 70.498 17.812 0.007414 8 4.142 -17V SY-4.2-SP3 41.783 736.173 84.227 25.908 0.000557 2342 0.054 -10V SY-4.2-SP8 41.762 736.439 81.207 24.977 0.002252 4653 0.090

[0065] In Table 2, Jsc is the short-circuit current density, Voc is the open-circuit voltage, FF is the fill factor, Eta is the photoelectric conversion efficiency, Rser is the series resistance, Rshunt is the parallel resistance, and IRev1 is the leakage current 1.

[0066] It can be seen from Table 1 that after the repair method of step 3 is implemented, the power of the components corresponding to a single JSIM battery (sample 1, sample 2) is increased by 0.73-0.85W. For JSIM battery components of different versions, the power increase can be increased accordingly with the number of JSIM batteries in the component. It can be seen that the method of repairing the power attenuation of solar cell components of the present invention has been verified in actual work.

[0067] As can be seen from Table 2, the negative bias voltage required for JSIM battery assemblies of different versions is in the range of -400V to -1000V. If the negative bias voltage deviates from -400V, it is equivalent to the negative bias voltage of each JSIM battery deviating from -14V (such as -10V). The power of the JSIM battery assembly will not recover, and may even continue to decrease. This is caused by insufficient bias and inadequate reset; if the negative bias voltage deviates from -1000V, it is equivalent to the negative bias voltage of each JSIM battery deviating from -25V (such as -32V). Excessive negative bias voltage will cause the JSIM battery to break down, which will not only increase leakage, but also may cause damage to the JSIM battery and the JSIM battery assembly. Therefore, in step 3, the negative bias voltage applied to each JSIM battery is preferably controlled within the range of -15V to -25V.

[0068] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0069] The technical solution provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for repairing power attenuation of solar cell modules, It is characterized in that The steps include: Step 1, preparing a solar cell that has been subjected to laser-assisted sintering; Step 2, using the solar cells processed by laser-assisted sintering to prepare the corresponding JSIM battery components; Step 3, applying a negative bias voltage to the JSIM battery assembly, and scanning the surface of the JSIM battery assembly with a laser to repair the power attenuation of the JSIM battery assembly; In step 3, the negative bias voltage applied to the JSIM battery assembly is controlled within the range of -400V to -1000V, and the laser power is 50-300W.

2. A method for repairing power attenuation of a solar cell module according to claim 1, It is characterized in that In step 3, the front side of the JSIM battery assembly is scanned using the laser.

3. A method for repairing power attenuation of a solar cell module according to claim 1 or 2, It is characterized in that In step 3, the time for repairing the JSIM battery assembly is controlled within the range of 5-300s.

4. A method for repairing power attenuation of a solar cell module according to claim 1 or 2, It is characterized in that In step 3, the spot size of the laser is 50-500 μm, the laser wavelength is 532 nm, 1030 nm or 1064 nm, and the laser scanning method is to perform full-surface scanning or line scanning on the JSIM battery assembly.

5. A method for repairing power attenuation of a solar cell module according to claim 1, It is characterized in that The JSIM battery assembly is provided with a junction box for conducting its current to the outside; In step 3, a negative bias voltage is applied to the JSIM battery assembly using the interface of the junction box.

6. A method for repairing power attenuation of a solar cell module according to claim 1, It is characterized in that In step 1, the solar cell is a TOPCon cell.

7. A method for repairing power attenuation of a solar cell module according to claim 6, It is characterized in that The step 1 specifically includes the following steps: Step 11, the silicon wafer is sequentially cleaned and textured, front boron diffusion doping is performed to prepare the emitter, pickled, back surface alkaline polished, back surface passivation contact structure is deposited, annealed, cleaned, front and back passivation films are deposited, screen printed and sintered to form front and back electrodes, so as to obtain a TOPCon battery; Step 12: Perform laser-assisted sintering on the front side of the TOPCon battery in step 11 to obtain a TOPCon battery that has been subjected to laser-assisted sintering.

8. A method for repairing power attenuation of a solar cell module according to claim 1, It is characterized in that The step 2 specifically includes the following steps: Step 21, slicing the solar cell processed by laser-assisted sintering to obtain a plurality of sliced ​​cells; Step 22, welding a plurality of sliced ​​batteries in series to obtain a battery string; Step 23, heating and laminating the photovoltaic front panel, the first packaging film, the battery string, the second packaging film and the photovoltaic back panel stacked in sequence from top to bottom to obtain a photovoltaic laminate; Step 24: Install the side of the photovoltaic laminate in the photovoltaic frame and install the junction box to obtain the JSIM battery assembly.

9. A method for repairing power attenuation of a solar cell module according to claim 8, It is characterized in that Before step 22, the method further includes the step of passivating the cutting edges of the sliced ​​cells.

10. A method for repairing power attenuation of a solar cell module according to claim 8, It is characterized in that In step 24, a sealant is injected to seal the side of the photovoltaic laminate in the photovoltaic frame, and the sealant is heated and cured to obtain the JSIM battery assembly.

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