Mode control of hydraulic circuit of solar hot water system collectors during the night time.

Relevance of this study is based on the implementation of the program of Scientific and Technological Development of the Russian Federation that determines transition to environmentally friendly and resource-saving technologies. The article presents the results of full-scale experimental research on the specific modes of operation of a hybrid solar water heating pilot unit at negative temperatures of outdoor air. Solutions are suggested to avoid freezing of heat transfer medium in hydraulic circuits of collectors during night hours. [ABSTRACT FROM AUTHOR]