Method for improving conversion efficiency of hit heterojunction solar cell

Abstract

The application discloses a method for improving conversion efficiency of a HIT heterojunction solar cell, which comprises the following steps: electrically connecting the HIT heterojunction solar cell with a direct current power supply, controlling the voltage of the direct current power supply to be less than the breakdown voltage of the HIT heterojunction solar cell, and making the bypass resistance in the HIT heterojunction solar cell heat and burn out; irradiating the HIT heterojunction solar cell with strong light to make unstable dangling bonds in the HIT heterojunction solar cell recombine into stable chemical bonds; disconnecting the electric connection between the HIT heterojunction solar cell and the direct current power supply, and stopping the irradiation of the HIT heterojunction solar cell with the strong light, so that the HIT heterojunction solar cell with improved conversion efficiency is obtained. The method eliminates the bypass resistance and the unstable dangling bonds by connecting the existing HIT heterojunction solar cell with the direct current power supply and irradiating the HIT heterojunction solar cell with the strong light, and greatly improves the conversion efficiency of the HIT heterojunction solar cell.

Description

Technical Field

[0001] This invention relates to a method for improving the conversion efficiency of solar cells, and more particularly to a method for improving the conversion efficiency of HIT heterojunction solar cells. Background Technology

[0002] Energy is the driving force of human socio-economic development and the foundation of social progress. This century presents humanity with the significant challenge of achieving sustainable economic and social development. How to achieve sustainable development under the severe circumstances of limited resources and environmental protection has become a global hot topic. All human activities are inseparable from energy, and social development depends on energy. Conventional energy sources such as coal, oil, and natural gas are scarce and insufficient, and their ability to support global development is limited. More importantly, the development and utilization of fossil fuels has led to problems such as the destruction of land resources, environmental pollution, and the greenhouse effect, causing irreparable damage to the human living environment. Solar energy is clean, inexhaustible, and free to use, requiring no transportation, thus meeting the requirements for future new energy development.

[0003] Currently, crystalline silicon solar cells remain the mainstream type of solar cell. Although the conversion efficiency of crystalline silicon solar cells has reached around 25%, the cost is still too high. This is because crystalline silicon solar cells require a high-temperature diffusion process to form a PN junction, and many complex processes are needed to achieve high conversion efficiency. To reduce costs while maintaining high conversion efficiency, using amorphous silicon / monocrystalline silicon heterojunctions is a good choice. HIT (Heterojunction with intrinsic Thinlayer) solar cells use an amorphous silicon thin film / monocrystalline silicon substrate heterojunction structure, combining the advantages of monocrystalline silicon and amorphous silicon solar cells, making it the best design to fully utilize the strengths of each.

[0004] HIT (Heterojunction Induction) solar cells combine the high efficiency and stability of crystalline silicon solar cells with the lower energy consumption and simpler manufacturing process due to the absence of high-temperature processes. Therefore, HIT solar cells exhibit better temperature characteristics than monocrystalline silicon cells, maintaining high output even at high temperatures. As a high-efficiency, low-cost solar cell, HIT solar cells have attracted significant attention in recent years and have become one of the development directions for solar cells. Currently, Sanyo's industrialized HIT solar cells have achieved an efficiency of 21%, with laboratory efficiencies exceeding 23%. Samsung, Jusung, and other companies have also achieved efficiencies greater than 21%.

[0005] The basic structure of a HIT heterojunction solar cell is a stacked structure consisting of a TCO-P-I-silicon wafer-I-N-TCO layer. In production practice, engineers have found that sunlight at midday in the heat can break down unstable dangling bonds in the cell structure and reform them into more stable bonds, thereby reducing defect density and improving the conversion efficiency of HIT heterojunction solar cells. However, this method of improving the conversion efficiency of HIT heterojunction solar cells has several drawbacks. First, it is affected by the natural environment and is only applicable during the hottest part of the day, resulting in limited practical industrial value and significance. Second, this method cannot eliminate the efficiency loss caused by the increase in leakage current due to micropore defects in the silicon wafer. For example, during the vapor deposition process of the P-I or I-N layers, if there are small pores in the thin film layer, the TCO will directly contact the silicon wafer, thereby increasing the leakage current and reducing the conversion efficiency of the cell (the equivalent circuit is: a set of leakage resistors (or bypass resistors) is connected in parallel next to the cell. This leakage resistor generates power consumption, which on the one hand causes the cell to heat up and reduces the conversion efficiency, and on the other hand consumes some output power, thus reducing the conversion efficiency). As can be seen from the above, the existing HIT heterojunction solar cell structure has the following two defects that lead to a decrease in conversion efficiency: (1) Due to defects in thin film deposition and silicon wafer manufacturing, the cell structure will generate bypass resistance, and the existence of bypass resistance will seriously reduce the conversion efficiency of the cell structure; (2) The existence of unstable dangling bonds leads to a decrease in the conversion efficiency of the cell structure.

[0006] Therefore, there is an urgent need for a method to improve the conversion efficiency of HIT heterojunction solar cells in order to solve the above-mentioned technical problems. Summary of the Invention

[0007] The purpose of this invention is to provide a method to improve the conversion efficiency of HIT heterojunction solar cells. This method eliminates bypass resistance and unstable dangling bonds by connecting a DC power supply to an existing HIT heterojunction solar cell and subjecting it to strong light irradiation, thereby greatly improving the conversion efficiency of the HIT heterojunction solar cell.

[0008] To achieve the above objectives, the present invention provides a method for improving the conversion efficiency of a HIT heterojunction solar cell, comprising the following steps: electrically connecting the HIT heterojunction solar cell to a DC power supply, controlling the voltage of the DC power supply to be less than the breakdown voltage of the HIT heterojunction solar cell, causing the bypass resistor inside the HIT heterojunction solar cell to heat up and burn out; irradiating the HIT heterojunction solar cell with strong light to cause the unstable dangling bonds inside to recombine into stable chemical bonds; disconnecting the electrical connection between the HIT heterojunction solar cell and the DC power supply, removing the irradiation of the HIT heterojunction solar cell with strong light, thereby obtaining a HIT heterojunction solar cell with improved cell conversion efficiency.

[0009] Compared to existing technologies, this invention electrically connects existing HIT heterojunction solar cells to a DC power supply. This causes the bypass resistance generated by silicon wafer defects within the HIT heterojunction solar cell to heat up and burn out, thereby eliminating the defective bypass resistance and improving the conversion efficiency of the HIT heterojunction solar cell. Simultaneously, the heat generated by the HIT heterojunction solar cell itself and the bypass resistance significantly increase the overall temperature of the solar cell. Combined with strong external light irradiation, this causes the unstable dangling bonds within the HIT heterojunction solar cell to recombine into stable chemical bonds, further improving the conversion efficiency. Therefore, this invention's dual-effect combined improvement of HIT heterojunction solar cell conversion efficiency is highly practical and suitable for widespread application.

[0010] Preferably, in the method for improving the conversion efficiency of HIT heterojunction solar cells according to the present invention, the HIT heterojunction solar cell is electrically connected to a DC power supply and its temperature is controlled between 100°C and 150°C. Attached Figure Description

[0011] Figure 1 This is the equivalent circuit diagram of an existing HIT heterojunction solar cell.

[0012] Figure 2 This is a schematic diagram of the principle of DC power supply connection and strong light irradiation treatment of existing HIT heterojunction solar cells according to the method of this invention.

[0013] Figure 3 yes Figure 2 Equivalent circuit diagram after processing according to the method of the present invention. Detailed Implementation

[0014] Embodiments of the invention will now be described with reference to the accompanying drawings, in which similar element reference numerals denote similar elements.

[0015] The present invention provides a method for improving the conversion efficiency of a HIT heterojunction solar cell, comprising the following steps: electrically connecting the HIT heterojunction solar cell to a DC power supply, controlling the voltage of the DC power supply to be less than the breakdown voltage of the HIT heterojunction solar cell, causing the bypass resistor inside the HIT heterojunction solar cell to heat up and burn out; irradiating the HIT heterojunction solar cell with strong light to cause the unstable dangling bonds inside to recombine into stable chemical bonds; disconnecting the electrical connection between the HIT heterojunction solar cell and the DC power supply, removing the irradiation of the HIT heterojunction solar cell with strong light, thereby obtaining a HIT heterojunction solar cell with improved cell conversion efficiency. This invention electrically connects a DC power supply to an existing HIT heterojunction solar cell, causing the bypass resistance generated by silicon wafer defects within the HIT heterojunction solar cell to heat up and burn out. This eliminates the defective bypass resistance within the HIT heterojunction solar cell, thereby improving its conversion efficiency. Simultaneously, the heat generated by the HIT heterojunction solar cell itself and the bypass resistance significantly increases the overall temperature of the cell. Combined with strong external light irradiation, this causes unstable dangling bonds within the HIT heterojunction solar cell to recombine into stable chemical bonds, further enhancing its conversion efficiency. Therefore, this invention's dual-effect combined improvement in the conversion efficiency of HIT heterojunction solar cells demonstrates strong practicality and suitability for widespread application.

[0016] Specifically, such as Figure 1 The existing HIT heterojunction solar cell shown has a bypass resistor 100 and a self-resistance 200. The bypass resistor 100 and the self-resistance 200 are connected in parallel. The presence of the bypass resistor 100 creates a leakage current, which generates power consumption. This causes the HIT heterojunction solar cell to heat up, reducing its conversion efficiency, and also consumes some output power, further decreasing the conversion efficiency. Therefore, as... Figure 2 The present invention connects the existing HIT heterojunction solar cell 1 to a DC power supply 2 capable of burning out the bypass resistor 100 and exposes it to strong light 3, thereby eliminating the bypass resistor 100 and the unstable dangling bond, greatly improving the conversion efficiency of the HIT heterojunction solar cell 1, and thus forming a... Figure 3 The equivalent circuit shown illustrates a HIT heterojunction solar cell with improved conversion efficiency, which has a self-resistance of only 200 ohms. More specifically, as... Figure 2As shown, the negative terminal of DC power supply 2 is electrically connected to the negative terminal of HIT heterojunction solar cell 1 via a contact pin 4 connected by a wire, and the positive terminal of DC power supply 2 is electrically connected to the positive terminal of HIT heterojunction solar cell 1 via a contact pin 5 connected by a wire. Arrow i indicates the current direction of DC power supply 2.

[0017] Preferably, in the method for improving the conversion efficiency of HIT heterojunction solar cells of the present invention, after the HIT heterojunction solar cell is electrically connected to the DC power supply, the temperature is controlled between 100°C and 150°C; within this temperature range, the structure of the HIT heterojunction solar cell is not damaged, and the conversion efficiency of the HIT heterojunction solar cell is optimized.

[0018] It is worth noting that the HIT heterojunction solar cell involved in this invention is an existing structural design, and its defects that lead to low conversion efficiency are also well known. Therefore, its structural design and defects leading to low conversion efficiency will not be described in detail here.

[0019] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for improving the conversion efficiency of HIT heterojunction solar cells, characterized in that, The process includes the following steps: Connecting the HIT heterojunction solar cell to a DC power supply; connecting the negative terminal of the DC power supply to the negative terminal of the HIT heterojunction solar cell via a contact pin connected by a wire; connecting the positive terminal of the DC power supply to the positive terminal of the HIT heterojunction solar cell via a contact pin connected by a wire; controlling the voltage of the DC power supply to be lower than the breakdown voltage of the HIT heterojunction solar cell, causing the bypass resistor inside the HIT heterojunction solar cell to heat up and burn out; irradiating the HIT heterojunction solar cell with strong light to reorganize the unstable dangling bonds inside it into stable chemical bonds; disconnecting the electrical connection between the HIT heterojunction solar cell and the DC power supply, and removing the strong light irradiation of the HIT heterojunction solar cell, thereby obtaining a HIT heterojunction solar cell with improved cell conversion efficiency.

2. The method for improving the conversion efficiency of a HIT heterojunction solar cell as described in claim 1, characterized in that, After the HIT heterojunction solar cell is electrically connected to a DC power source, its temperature is controlled between 100℃ and 150℃.

Images