PV, Semiconductors & Optical Fibres

Graphite, with its exceptional properties such as high-temperature resistance, corrosion resistance, and excellent thermal and electrical conductivity, finds extensive applications across multiple core stages in the photovoltaic (PV) field, ranging from silicon material smelting to battery manufacturing and thermal field management. The specific applications are as follows:

1. Silicon Material Production

  1. Metallurgical Silicon Smelting: In metallurgical silicon smelting furnaces, electrodes are the core components of the conductive system. High-purity graphite electrodes, due to their excellent electrical conductivity, low resistivity, high melting point, low thermal expansion coefficient, high mechanical strength at high temperatures, and low impurity content, are the optimal choice for chemical silicon smelting. They generate electric arcs by conducting current, enabling efficient smelting of chemical silicon.

  2. Polysilicon Production: The modified Siemens process is the mainstream method for polysilicon production, where high-purity graphite plays a crucial role in chemical vapor deposition reduction furnaces and thermal hydrogenation furnaces. For instance, graphite components are used to fix silicon cores and transmit current in reduction furnaces, while thermal hydrogenation furnaces utilize graphite heating elements to heat raw materials for reduction reactions. Additionally, graphite heat exchange equipment enhances thermal efficiency and reduces heat loss through heat exchange.

  3. Polysilicon Ingot Furnaces: The heating elements and insulation materials in polysilicon ingot furnaces demand extremely high graphite performance. Heating elements must operate stably at temperatures above 1650°C without reacting with silicon materials, while insulation materials require high-temperature resistance, low density, and low thermal conductivity. High-purity graphite, with its low thermal inertia, high heating efficiency, and excellent chemical stability, is the ideal choice for both heating elements and insulation materials.

2. Monocrystalline Silicon Growth

  1. Single-Crystal Furnace Thermal Fields: The thermal field of a single-crystal furnace is the core equipment for monocrystalline silicon growth, where graphite components (such as heating elements, crucibles, and insulation covers) must possess high purity, high strength, and excellent thermal conductivity. High-purity graphite materials ensure uniform growth and high quality of monocrystalline silicon, improving yield and performance. For example, isostatic graphite, with its isotropic structure and uniformity, is widely used in single-crystal furnace thermal fields.

  2. Graphite Boats: During the manufacturing process of solar cells, graphite boats provide a thermal field environment for silicon materials, facilitating their melting and crystallization. Their high thermal conductivity, high strength, and corrosion resistance ensure uniform heating of silicon materials, enhancing battery quality and efficiency.

3. Battery Manufacturing

  1. Electrode Materials: Graphite electrodes, due to their excellent electrical conductivity and high chemical stability, are widely used in the electrode preparation of photovoltaic batteries. They reduce electrode resistance and improve the output power and conversion efficiency of photovoltaic batteries. For instance, using graphite electrodes can increase the output power of photovoltaic batteries by approximately 1.5 times.

  2. Back Surface Field Materials: In crystalline silicon photovoltaic batteries, graphite, as a back surface field material, reflects photo-generated carriers, reducing carrier recombination at the battery's back surface. This enhances the short-circuit current and open-circuit voltage of the battery, further improving photoelectric conversion efficiency.

4. Other Applications

  1. Photovoltaic Support Materials: Graphite fibers, with their high strength and high modulus mechanical properties, can be used to manufacture supports for photovoltaic power stations, improving the installation efficiency and service life of photovoltaic arrays.

  2. Adsorption and Purification: Graphite materials can be used for waste gas treatment and wastewater treatment in photovoltaic production, adsorbing harmful gases and pollutants to achieve environmental protection goals. For example, graphite heating elements produce a purification effect during heating, simplifying vacuum system configurations.