Maysun Solar
Maysun Solar
Working Principle and Structural Features of TOPCon Solar Cells
TOPCon solar cells utilize an ultra-thin oxide layer (1~2nm) to enable effective tunneling of majority carriers, significantly reducing the rate of minority carrier recombination, thereby effectively enhancing the cell's open-circuit voltage and short-circuit current, and further increasing the cell's conversion efficiency.
Structurally, the front design of TOPCon solar cells is similar to conventional N-type or N-PERT solar cells, but the key technological innovation lies in its rear passivated contact structure. This structure includes an ultra-thin silicon oxide layer and a phosphorus-doped microcrystalline-amorphous silicon mixed thin film. The passivation performance is activated through an annealing process, during which the crystallinity of the silicon thin film undergoes a transformation from a microcrystalline-amorphous mixed phase to a polycrystalline phase, further enhancing the cell's performance. Under an annealing condition of 850°C, the cell exhibits excellent passivation effects, with an open-circuit voltage exceeding 710 mV and an electron recombination rate reduced to 9-13 fA/cm^2, significantly boosting the cell efficiency.
Production Process of N-TOPCon Solar Cells
TOPCon solar cells utilize an ultra-thin oxide layer (1~2nm) to enable effective tunneling of majority carriers, significantly reducing the recombination rates of minority carriers. This effectively increases the open-circuit voltage and the short-circuit current of the cell, thereby boosting the cell's conversion efficiency. Structurally, the front design of TOPCon solar cells resembles that of conventional N-type or N-PERT solar cells. The key innovation lies in their rear passivated contact structure, which includes an ultra-thin layer of silicon oxide and a layer of phosphorus-doped microcrystalline-amorphous silicon film. Through the annealing process, the passivation properties are activated, and the crystallinity of the silicon film is transformed from a microcrystalline-amorphous mix to a polycrystalline phase, further improving cell performance. With annealing at 850°C, the cells exhibit excellent passivation effects, with open-circuit voltages exceeding 710 mV and electron recombination rates dropping to 9-13 fA/cm^2, significantly enhancing cell efficiency.
The production process of TOPCon solar cells maximizes the use of existing traditional production methods for P-Type cells, requiring only the addition of boron diffusion and thin film deposition equipment, without the need for backside opening and alignment. This significantly simplifies the cell production process and reduces the difficulty of mass production. The manufacturing process of TOPCon cells includes:
1.Texturization (Texture): Utilization of physical or chemical methods to texture the surface of the silicon wafer, enhancing light absorption.
2.Boron Diffusion (Diffusion LP-BBr₃): Use of low-pressure boron tribromide gas for P-Type boron diffusion to form the emitter zone.
3.Laser Selective Emitter: Application of laser technology to treat the surface of the silicon wafer, creating selective emitter areas.
4.Chemical Edge Isolation: Removal of excess material at the edges of the silicon wafer using chemical means, to reduce surface defects.
5.TOPCon Oxidation: Growth of an oxide layer on the surface of the silicon wafer for surface passivation and reduction of electron-hole pair recombination.
6.TOPCon PECVD: Deposition of a tunnel oxide layer and a polycrystalline silicon layer using PECVD technology to form passivated contacts.
7.TOPCon High-Temperature Anneal (TOPCon: High-T anneal): Activation of the tunnel oxide layer and the polycrystalline silicon layer through high-temperature annealing treatment to enhance cell efficiency.
8.Alumina Deposition (Al₂O₃ front): Deposition of an alumina layer on the front side of the wafer to further improve surface passivation.
9.Silicon Nitride Deposition (PECVD SiNx front & rear): Deposition of silicon nitride layers on the front and back sides of the wafer for passivation and anti-reflection.
10.Printing: Use of screen printing technology to print metal electrodes on the silicon wafer.
11.Firing: Bonding the metal electrodes with the silicon wafer through high-temperature sintering to form electrical connections.
12.Testing and Sorting: Testing the finished cells for performance and sorting based on efficiency.
This process maximizes the utilization of existing traditional production methods for P-Type cells, requiring only the addition of boron diffusion and thin film deposition equipment, simplifying the cell production process, and reducing the difficulty of mass production. The TOPCon technology is highly compatible with PERC production lines, adding the processes of boron diffusion and the tunnel layer + p-Poly layer, while the other steps essentially continue those of the PERC production lines.
Comparison of N-TOPCon and PERC Technology
Advantages of TOPCon Technology
- High Conversion Efficiency: TOPCon cells stand out for their high conversion efficiency. The mass production efficiency of TOPCon cells can currently reach 24.5%-25%, which is higher than the current average mass production conversion efficiency of 23.2% for PERC cells. With the theoretical conversion efficiency limit being above 24.5%, it suggests that TOPCon cells have greater improvement potential.
- Enhanced Overall Power Generation: Compared to PERC cells, TOPCon cells have a higher bifacial factor, which can enhance the overall power generation. The bifacial factor of TOPCon solar panels can reach up to 85%, significantly higher than the 70% of PERC components. This means that the power gain can increase by up to 2%.
- Extended Power Warranty Period: The N-type cell silicon substrate is doped with phosphorus, avoiding the loss of electron capture caused by boron-oxygen pairs, almost eliminating light-induced degradation, and ensuring a longer power warranty period.
- Upgrade Compatibility with Low Equipment Investment: TOPCon is compatible with PERC production lines and can be upgraded based on PERC lines. Compared to PERC, the equipment added or replaced includes boron diffusion for the preparation of tunnel oxide and polysilicon layers, with the rest of the process being largely compatible with PERC production lines.
Applications of TOPCon Solar Modules
High Efficiency for Residential and Commercial Use: Suitable for rooftop or ground-mounted solar systems, providing clean, renewable energy for homes, businesses, or industrial facilities.
Utility-Scale Solar Power Plants: In large solar power fields, TOPCon solar panels, due to their high efficiency, can generate more power in limited space, making them ideal for large-scale power generation applications, helping to reduce the cost per unit of electricity.
Agricultural Applications: TOPCon panels can power agricultural equipment, such as water pumps and irrigation systems, especially in remote or off-grid areas, serving as an independent energy solution to help farmers increase agricultural productivity.
Electric Vehicle Charging Stations: With the increasing popularity of electric vehicles, the demand for sustainable energy solutions is growing. TOPCon solar panels can provide clean energy for electric vehicle charging stations, promoting the development of green transportation.
Building-Integrated Photovoltaics (BIPV): Solar panels utilizing TOPCon technology can be integrated into the design of buildings, serving as part of the construction materials, not only providing energy but also enhancing the aesthetic appeal of the buildings.
Coastal Areas: Due to their high durability, TOPCon solar panels are also suitable for use in offshore or coastal areas, where there may be higher levels of salt mist and humidity.
Future Development Predictions for TOPCon Solar Modules
TOPCon solar cells are expected to experience significant market growth between 2023 and 2030, thanks to their high conversion efficiency and durable performance. As the technology matures and production scales up, costs are anticipated to decrease further, increasing the market penetration of TOPCon modules in large photovoltaic power stations and commercial applications. Policy support and sustainable development trends are further accelerating the adoption of TOPCon technology. Global demand for TOPCon technology is expected to continue growing with the increasing need for clean energy solutions, especially in regions with abundant sunlight. This will drive technological innovation and market expansion in the photovoltaic industry.
Reference:
https://guangfu.bjx.com.cn/news/20200710/1088087.shtml
https://guangfu.bjx.com.cn/news/20200710/1088087.shtml
https://xueqiu.com/2305761063/241967340
https://guangfu.bjx.com.cn/news/20200710/1088087.shtml
https://www.sohu.com/a/640762583_121123896
https://www.novergysolar.com/topcon-vs-perc-vs-hjt-solar-cells/#Uses_of_Topcon_Solar_Panels
https://www.verifiedmarketreports.com/product/topcon-solar-cell-and-module-market/
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