A method for improving the efficiency of a finished heterojunction solar cell

Abstract

The application discloses a method for improving the efficiency of a finished heterojunction solar cell, and comprises the following steps: firstly, preheating the cell piece, the preheating temperature is 150-220 DEG C, and the time is 1-10 min; at the same time of preheating, light treatment is performed on the cell, the light time is 1-10 min; after the light treatment, the cell is cooled, the temperature is kept at 100-150 DEG C, then the cell is powered on, and the power-on time is 5-30 min. The application creatively uses light injection as a method for activating electron hole pairs and defect activity, combines with electric injection, continuously excites electron hole pairs and combines with hydrogen atoms in amorphous silicon to form hydrogen ions, passivates defects at the interface of amorphous silicon and silicon piece, the passivation effect is stable, the passivation effect is better than that of short-time high-light-intensity light injection, the power requirement of the required light source and power source is low, high-power light source and power source are not needed, the comprehensive cost is low, and the method is suitable for heterojunction cell production line production.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a method for improving the efficiency of finished heterojunction solar cells. Background Technology

[0002] With the development and application of solar cells, high-efficiency and low-cost cells are becoming increasingly popular in the market. In recent years, the call for grid parity has grown stronger, and the winning bid prices for the Top Runner Program have begun to approach grid parity on the generation side. Therefore, the development of high-efficiency cells has received high attention from major photovoltaic companies. Silicon-based heterojunction (HIT) solar cells with intrinsically passivated amorphous silicon layers, interdigitated back contact (IBC) solar cells, and the increasingly popular tunneling oxide back passivated (TOPCon) solar cells are considered the future directions for high-efficiency solar cells. Among them, silicon-based heterojunction (HIT) cells, due to their high open-circuit voltage, high conversion efficiency, low temperature coefficient, and absence of light-induced degradation (LID) and electrically induced degradation (PID), have become the most promising type of high-efficiency cell in the industry. Silicon-based heterojunction (HIT) cells also have advantages such as low fabrication temperature, fewer process steps, bifacial power generation, and the ability to use ultra-thin silicon wafers to reduce costs, making them likely to become a photovoltaic product that dominates the market in the future.

[0003] A light injection process for heterojunction solar cells has been developed, which uses short-duration high-intensity light (maximum 80,000 W / m² 250s) to passivate defects at the silicon wafer-amorphous silicon interface, thereby improving the cell's electrical performance. However, the passivated defects are unstable; the passivation effect gradually disappears over time, and it also loses its passivation effect quickly during the lamination and heat treatment process in module manufacturing. This manifests as a large rate of cell degradation during static storage, or a significant decrease in cell efficiency after heat treatment, resulting in lower-than-expected module power. Furthermore, this technology requires high light intensity, leading to high lamp source costs, short lifespans, and consequently, high overall equipment costs.

[0004] Currently, the mass production efficiency of silicon-based heterojunction (HIT) solar cells has reached 23.5%, and the power output of 60-cell bifacial glass modules has exceeded 335W. However, with continuous improvements in manufacturing processes, efficiency enhancement has reached a bottleneck, and the high production cost of heterojunction cells significantly restricts their development. Therefore, it is necessary to add new processes beyond the existing ones to further improve cell efficiency and module power output, while simultaneously reducing production costs in various aspects to achieve grid parity or even lower grid-connected electricity prices than existing thermal power, in order to accelerate the large-scale industrialization of silicon-based heterojunction solar cells. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for improving the efficiency of finished heterojunction solar cells that has lower requirements for illumination lamp sources and electrical injection power sources, does not require high-power lamp sources and power sources, is low in cost, and is suitable for silicon-based heterojunction production lines.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for improving the efficiency of finished heterojunction solar cells, the method comprising the following steps:

[0007] First, preheat the battery cells at a temperature of 150℃-220℃ for 1-10 minutes.

[0008] While preheating, the battery is subjected to light treatment for 1-10 minutes.

[0009] After light treatment, the battery is cooled down to 100℃-150℃, and then the battery is powered on for 5-30 minutes.

[0010] Furthermore, the heating method for preheating the battery cells includes, but is not limited to, hot air heating, infrared heating, and electric heating plate heating.

[0011] Furthermore, the light source used for the illumination treatment is, but is not limited to, LED light sources or halogen light sources, with a light intensity of 5000W / m². 2 -10000W / m 2 .

[0012] Furthermore, the power-on process uses a constant current power supply with a constant current of 10A-20A.

[0013] As can be seen from the above description of the structure of the present invention, compared with the prior art, the present invention has the following advantages:

[0014] 1. This invention creatively uses light injection as a method to activate electron-hole pairs and defect activity. Combined with electrical injection, it continuously excites electron-hole pairs to combine with hydrogen atoms in amorphous silicon to form hydrogen ions, passivating defects at the interface between amorphous silicon and silicon wafer. The passivation effect is stable and better than that of short-term high-intensity light injection. Specifically, the battery efficiency improvement is roughly the same, the battery efficiency decays little after standing, and the battery efficiency decreases little after heat treatment at 160°C for 20 minutes.

[0015] 2. The present invention requires low power for light sources and power supplies, eliminating the need for high-power light sources and power supplies, resulting in low overall cost and suitability for heterojunction cell production lines. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0017] Figure 1 This is a flowchart of a method for improving the efficiency of finished heterojunction solar cells according to the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] Example 1

[0020] refer to Figure 1 The process method for improving the efficiency of finished silicon-based heterojunction solar cells in this embodiment involves preheating the cell to 190°C with hot air before initiating light injection. The light injection intensity is 5000 W / m², and the light injection time is 6 minutes. The cell is then cooled to 140°C, and electrical injection begins at a current of 12 A for 25 minutes. The initial electrical performance, the electrical performance after treatment, the electrical performance after one month of rest in darkness, and the electrical performance after subsequent heat treatment are all tested.

[0021] Example 2

[0022] The process method for improving the efficiency of finished silicon-based heterojunction solar cells in this embodiment involves preheating the cell to 150°C with hot air before initiating light injection. The light injection intensity is 10000 W / m², and the light injection time is 3 minutes. The cell is then cooled to 120°C, and electrical injection begins at a current of 18 A for 15 minutes. The initial electrical performance, the electrical performance after treatment, the electrical performance after one month of rest in darkness, and the electrical performance after subsequent heat treatment are all tested.

[0023] Example 3

[0024] The process method for improving the efficiency of finished silicon-based heterojunction solar cells in this embodiment involves preheating the cell to 170°C with hot air before initiating light injection. The light injection intensity is 7000 W / m², and the light injection time is 5 minutes. The cell is then cooled to 100°C, and electrical injection begins at a current of 20 A for 10 minutes. The initial electrical performance, the electrical performance after treatment, the electrical performance after one month of rest in darkness, and the electrical performance after subsequent heat treatment are all tested.

[0025] Control example: Existing light injection technology was used as a control example. The light injection intensity was 50,000 W / m², the light injection time was 1 min, and the battery temperature was controlled at 220℃. The initial electrical performance of the battery, the electrical performance after treatment, the electrical performance after one month of rest in darkness, and the electrical performance after heat treatment were all tested simultaneously.

[0026] Electrical performance comparison table after one month of rest following the treatment in the example.

[0027] Eta gain (relative to initial value) initial After processing Let it sit for a month Example 1 0 0.38 0.31 Example 2 0 0.33 0.29 Example 3 0 0.37 0.33 Implementation Comparison Example 0 0.35 0.14

[0028] Comparison table of electrical properties after processing and heat treatment in the examples

[0029] Eta gain (relative to initial value) initial After processing Heat treatment Example 1 0 0.37 0.31 Example 2 0 0.33 0.3 Example 3 0 0.39 0.32 Implementation Comparison Example 0 0.43 0.19

[0030] In the above embodiment, the activity of electron-hole pairs and defects within the battery is stimulated by short-term, low-intensity light irradiation while the battery is at a certain temperature. Then, through electro-injection, the electron-hole pairs are continuously excited and combine with hydrogen atoms within the amorphous silicon to form hydrogen ions with a passivating effect, thereby passivating defects at the interface between the amorphous silicon and the silicon wafer. This method provides a good passivation effect, and the passivated defects are stable and not easily decomposed, resulting in a significant improvement in battery efficiency and a low rate of degradation after static storage. This invention has low requirements for the irradiation lamp source and the electro-injection power supply, eliminating the need for high-power lamp sources and power supplies, thus reducing costs and making it suitable for heterojunction battery production lines.

[0031] This invention creatively uses light injection as a method to activate electron-hole pairs and defect activity. Combined with electrical injection, it continuously excites electron-hole pairs to combine with hydrogen atoms in amorphous silicon to form hydrogen ions, passivating defects at the interface between amorphous silicon and silicon wafer. The passivation effect is stable and better than that of short-term high-intensity light injection. Referring to the electrical performance comparison table, the specific performance is that the battery efficiency improvement is roughly the same, the battery efficiency decay is small after resting, the battery efficiency decreases little after heat treatment at 160℃ for 20 minutes, the required power of light source and power supply is low, no high-power light source and power supply are required, the overall cost is low, and it is suitable for heterojunction battery production lines.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving the efficiency of finished heterojunction solar cells, characterized in that: The method includes the following steps: First, the solar cell is preheated. The solar cell is a heterojunction solar cell. The preheating temperature is 150℃-220℃ and the time is 1min-10min. While preheating, the battery is subjected to light treatment for 1-10 minutes. After light treatment, the battery is cooled down to 100℃-150℃, and then the battery is powered on for 5-30 minutes; the light intensity of the light treatment is 5000W / m2-10000W / m2. The power-on process uses a constant current power supply with a constant current of 10A-20A.

2. The method for improving the efficiency of finished heterojunction solar cells according to claim 1, characterized in that: The preheating methods for the battery cells include hot air heating, infrared heating, or electric heating plate heating.

3. The method for improving the efficiency of finished heterojunction solar cells according to claim 1, characterized in that: The lighting source for the illumination treatment uses an LED light source or a halogen light source.

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