The article is devoted to the study of the efficiency of the structural elements of the solar collector in cloudy conditions with the stabilization of heat transfer due to the use of terrestrial radiation. The study involves experimental verification of theoretically obtained assumptions about the use of terrestrial radiation to improve the efficiency of the solar installation. Proposed a hybrid version of a solar installation using solar and terrestrial radiation. Based on the results of laboratory and field experimental tests, the efficiency of the offered hybrid installation is confirmed, positive results from short-term compensations of decrease in solar irradiation, e.g., due to clouds, are received. In addition to the known characteristics of heat collectors, for a hybrid installation, such a design parameter as the ratio of the heat capacity of the accumulator and the collector seems to be essential. The increase in the indicator characterizes the increase in the time of effective operation in the presence of clouds. The tests showed a significant impact on the operation of the installation of external factors such as the position of the Sun, ambient temperature, wind speed, etc. This will be taken into account in the further justification of the design of the hybrid installation and its parameters.