A process for passivating and contacting an assembly end auxiliary battery

Abstract

This invention relates to the field of solar photovoltaic module technology, specifically disclosing a process method for auxiliary cell passivation and contact at the module end. The process method is as follows: after the solar cells are string-welded, laminated, and encapsulated to form a solar module, the module is placed in an environmental chamber for illumination, with the temperature set at 50℃~75℃ and the irradiance at 1000Wh / m². 2 ~1500Wh / m 2 The forward current is 2–5 A, and the illumination time is 1–4 hours. This invention demonstrates excellent internal defect repair effects on solar cells using LECO technology under high irradiance, medium temperature, and low current conditions. It can further optimize the contact between the metal electrode and silicon, improve the FF and Voc values ​​of the solar module, and thus significantly increase the power of the solar module. It can also assist in optimizing the contact resistance and passivation effect at the module end, thereby improving the module power without adding new equipment to the production line and without affecting production efficiency.

Description

Technical Field

[0001] This invention relates to the field of solar photovoltaic module technology, and specifically discloses a process method for auxiliary cell passivation and contact at the module end. Background Technology

[0002] With the development of solar cell technology, the development of high-efficiency cells and modules has received increasing attention. n-Topcon cells have attracted much attention from researchers at home and abroad due to their characteristics such as low processing temperature, high conversion efficiency, good cell stability and low temperature coefficient. How to further improve the power of modules at the module manufacturing stage has also become a key focus of the industry.

[0003] Currently, LECO (laser-assisted sintering) technology has been added to the battery side to increase cell efficiency. LECO technology cells use a special silver paste (the original Topcon cells used silver-aluminum paste on the front). The laser can precisely heat the silver paste, locally destroying the passivation layer. Under high temperature, silver particles begin to react with silicon, locally forming a silver-silicon alloy. This alloy junction has a low contact resistance.

[0004] However, the contact resistance and passivation effect of the packaged module cannot be optimized at the battery end. To address this, Aikon first improved the light injection process and published patent CN114122197A. This mainly involves adding a light injection process after lamination. The light injection process is completed after lamination and before testing. The module reaches a temperature of 150°C after lamination, and the light injection equipment is heated to a certain temperature to achieve the desired light injection effect. After connecting the light injection equipment to the laminator, the module, already at a certain temperature after lamination, will better accept light injection, thus improving power output. However, this method is only suitable for cells without LECO technology, primarily applicable to heterojunction cells, and requires the addition of new equipment to the production line, increasing costs and impacting production efficiency. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a process method for auxiliary battery passivation and contact at the component end.

[0006] This invention discloses a process method for auxiliary battery passivation and contact at the component end, employing the following technical solution:

[0007] A process for passivation and contact of auxiliary cells at the module end involves placing the battery module in an environmental chamber for light irradiation after the cells have been string-welded, laminated, and encapsulated. The temperature is set at 50℃~75℃ and the irradiance is 1000Wh / m². 2 ~1500Wh / m 2 The forward current is 2-5A, and the illumination time is 1-4 hours.

[0008] Preferably, this process is for battery modules composed of cells using LECO technology.

[0009] Preferably, this process is for battery modules composed of cells using LECO technology-specific silver paste.

[0010] Preferably, the battery assembly is placed in an environmental chamber with a temperature of 50°C and an irradiance of 1000Wh / m². 2 The forward current is 3A.

[0011] Preferably, the battery assembly is placed in an environmental chamber with a temperature of 60°C and an irradiance of 1000Wh / m². 2 The forward current is 2.5A.

[0012] Preferably, the battery assembly is placed in an environmental chamber with a temperature of 55°C and an irradiance of 1000Wh / m². 2 The forward current is 4A.

[0013] Compared with the prior art, the present invention has at least the following beneficial effects:

[0014] 1. Under high irradiance, medium temperature, and low current conditions, the LECO technology can effectively repair internal defects in solar cells, resulting in better passivation. In addition, the contact between the metal electrode and silicon can be further optimized to improve the FF and Voc values ​​of the solar module, thereby significantly increasing the power of the solar module.

[0015] 2. The process method of the present invention can help optimize the contact resistance and passivation effect of the component, thereby improving the component power without adding new equipment to the production line and without affecting production efficiency. Detailed Implementation

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to specific embodiments.

[0017] After lamination is completed, the electrical performance parameters of solar cell modules typically reach their peak, after which they will degrade due to environmental factors. For existing LECO (laser-assisted sintering) technology cells, special processes are used at the module end to further enhance the passivation and contact effects of the cells, thereby increasing the module's power output.

[0018] Example 1

[0019] This embodiment discloses a process method for auxiliary cell passivation and contact at the module end. After the cells are connected in series, laminated, and encapsulated to form a battery module, the battery module undergoes a power test. Then, the battery module is placed in an environmental chamber for light irradiation, with the temperature set at 50°C and the irradiance at 1000Wh / m². 2 The forward current was 3A, and the illumination period was 2 hours. After the illumination period, the components were cooled down to the standard test temperature before the power test was conducted.

[0020] Example 2

[0021] This embodiment discloses a process method for auxiliary cell passivation and contact at the module end. After the cells are connected in series, laminated, and encapsulated to form a battery module, the battery module undergoes a power test. Then, the battery module is placed in an environmental chamber for light irradiation, with the temperature set at 60°C and the irradiance at 1000Wh / m². 2 The forward current was 2.5A, and the illumination period was 2 hours. After the illumination period, the components were cooled down to the standard test temperature before the power test was conducted.

[0022] Example 3

[0023] This embodiment discloses a process method for auxiliary cell passivation and contact at the module end. After the cells are connected in series, laminated, and encapsulated to form a battery module, the battery module undergoes a power test. Then, the battery module is placed in an environmental chamber for light irradiation, with the temperature set at 55°C and the irradiance at 1000Wh / m². 2 The forward current was 4A, and the illumination period was 2 hours. After the illumination period, the components were cooled down to the standard test temperature before the power test was conducted.

[0024] Performance testing:

[0025] Test 1: The process method of this invention is compared with the power data of batteries that have undergone LECO technology and those that have not.

[0026] Table 1

[0027]

[0028] As shown in Table 1, it can be seen that the power of the module increases by 3-5W after using LECO cells, while the power of the cell without LECO technology remains basically unchanged.

[0029] Test 2: The power output of the process method of this invention and the process method of the prior art were compared using LECO battery modules.

[0030] Table 2

[0031]

[0032] As shown in Table 2, it can be seen that the power of the battery module is relatively improved by using the process method of the present invention under high irradiance, medium temperature and weak current conditions, while the power of the battery module is relatively reduced by using the process method of the prior art under ultra-high irradiance, high ambient temperature and strong current conditions.

[0033] Test 3: Verify the impact of changes in current value in the process method of this invention on the component power.

[0034] Table 3

[0035]

[0036] As shown in Table 3, it can be seen that in the process method of the present invention, the current value during light treatment should not be too large or too small. When the current value is 7A, the power only increases by less than 1W, and the improvement effect is not obvious. When the current value is 1A, the power basically does not change. Only under a weak current of 2 to 5A can atoms with poor adhesion to the passivation layer escape, thereby improving the passivation effect and achieving a better increase in the power of the battery module.

[0037] The process method of this invention, under high irradiance, medium temperature, and low current conditions, can, to a certain extent, better repair the internal defects of solar cells using LECO technology, resulting in better passivation. Simultaneously, it can further optimize the contact between the metal electrode and the silicon substrate, significantly improving the FF value of the solar module and slightly increasing Voc. This leads to lower series resistance and higher parallel resistance in the LECO-technology-equipped solar cells, thereby increasing the power of the solar module. Furthermore, it requires no new equipment to be added to the production line and will not affect production efficiency.

[0038] On the one hand, although LECO technology can precisely destroy the passivation layer of the solar cell, the passivation layer will still be slightly damaged. Under appropriate environmental conditions, as the temperature gradually rises to the range of 50℃~75℃, and an appropriate weak current of 2~5A is added, atoms that originally had poor adhesion to the passivation layer will escape, which will slightly increase the minority carrier lifetime of the silicon wafer, enhance the passivation effect, and slightly improve Voc.

[0039] On the other hand, LECO technology uses a special pure silver paste. Silver has better current permeability. Under high irradiance conditions, the contact resistance of the current generated by photons passing through the grid line will be reduced, thus greatly improving the FF value.

[0040] The technical solution provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A process for passivating and contacting auxiliary cells at the component end, characterized in that, After the solar cells are strung together, laminated, and encapsulated to form a battery module, the battery module is placed in an environmental chamber for light exposure, with the temperature set at 50℃~75℃ and the irradiance at 1000W / m². 2 ~1500W / m 2 The forward current is 2~5A, and the illumination time is 1~4h; This process method is for battery modules composed of cells using LECO technology.

2. The process method for passivation and contact of auxiliary cells at the component end according to claim 1, characterized in that, This process method is for battery modules composed of cells using LECO technology-specific silver paste.

3. The process method for passivation and contact of auxiliary cells at the component end according to claim 1, characterized in that, The battery assembly was placed in an environmental chamber with a temperature of 50°C and an irradiance of 1000 W / m². 2 The forward current is 3A.

4. The process method for passivation and contact of auxiliary cells at the component end according to claim 1, characterized in that, The battery assembly was placed in an environmental chamber with a temperature of 60°C and an irradiance of 1000 W / m². 2 The forward current is 2.5A.

5. The process method for passivation and contact of auxiliary cells at the component end according to claim 1, characterized in that, The battery assembly was placed in an environmental chamber with a temperature of 55°C and an irradiance of 1000 W / m². 2 The forward current is 4A.

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