The final paper presents the influence of temperature on the efficiency of solar photovoltaic systems. For this purpose, photovoltaic panels based on polycrystalline silicon and thin-film photovoltaic panel based on cadmium telluride were used. In the theoretical part, the influence of the surface temperature of the photovoltaic panel on its operating parameters, such as voltage-current and power, is explained. For the purpose of completeness of the theoretical part, photovoltaic panels based on polycrystalline silicon and cadmium telluride are described, with a presentation of technical data and operating characteristics. In the practical part of the final paper, both laboratory systems with the corresponding measuring equipment are described. The measurement results demonstrated the operation of the system in real conditions, with special emphasis on measuring the surface temperature of photovoltaic panels, with continuous monitoring of their operating parameters. The data obtained by measurement were processed by a spreadsheet and presented in graphical form, with special emphasis on the relationship between temperature and energy conversion efficiency.