Abstract
Thr paper presents the results of studies of a two-circuit solar installation with thermosiphon circulation in the winter period. The heat pump is integrated with a conventional solar heating system, in which the temperature of the collected heat is reduced from 20 to 30 °C to increase the efficiency of solar energy collection. The low-temperature heat collected by the solar collector is upgraded using a heat pump to generate high-temperature heat for heating rooms in winter and low-pressure process steam for industrial use in other seasons. The results show that the efficiency of the solar collector has increased by 30.50%, its annual effective opera¬ting time has reached 2000 hours, which exceeds by nearly four times that of a conventional solar heating system. To compare the effectiveness of the two options, the tests were carried out under the same climatic conditions on the same day day, from 12 to 15 hours, when the air temperature and the intensity of solar radiation are most stable.