The article presents the development of a regression mathematical model designed to assess the thermal performance of a parabolic trough solar collector (PTC). The main factors included in the model are the density of the solar flux and the temperature of the coolant. The least squares method was used to build the model, which made it possible to minimize deviations between the measured and predicted values of thermal performance. The result of the work is a regression model that enables highly accurate prediction of the thermal power of the PTC in various climatic and operating conditions. The proposed model can be used to improve the accuracy of forecasts and optimize the operation of the PTC, enhancing its energy efficiency in the design and operation of solar PTCs.