Silicon-based solar cells are currently the most widely used, accounting for 90.9% of the global photovoltaic module production. Solar radiation in the wavelength range of 400 to 1200 nm is effectively absorbed by crystalline silicon solar cells and converted into electrical energy, and the remaining energy is converted into thermal energy. The efficiency of silicon-based solar cells is very sensitive to temperature. For every 1 °C increase in the temperature of the photovoltaic panel, the efficiency will decrease by 0.5–0.65%. Down-conversion nanoparticles can convert ultraviolet rays into visible light that is easy for photovoltaic panels to absorb. This paper first established a thermodynamic model for coating titanium dioxide nanoparticles with a grain size of 20 nm on the surface of crystalline silicon solar panels and experimentally confirmed that this method can effectively reduce the operating temperature of silicon-based photovoltaic panels while ensuring electrical performance.