In solar power plants, heat transfer fluids are used in concentrators like linear Fresnel and parabolic trough systems for efficient energy generation and thermal storage. Molten salts and synthetic heat transfer fluids are utilized based on their ability to function at various temperature ranges, contributing to the generation of electricity and the manufacturing of polysilicon for photovoltaic cells. These fluids assist in the purification and cooling steps of polysilicon production, essential for creating high-purity silicon for solar and electronic applications.