Abstract: A hot water solar system receives water from a source and heats it in solar panels. From the solar panels it is circulated through a supplemental heater and through a domestic heating system and thus made available for domestic use in washers and baths and is then recirculated through the solar panels. In the event the solar panels will not increase the temperature of the water 1.5.degree. C. the water is not circulated through the solar panels but merely circulated back through the supplemental heater and the household loop. In the event the water in the solar panels approach a freezing temperature, water may be circulated from the household loop to the solar panels to prevent freezing. Water is also circulated from a solar storage tank through the solar panels at a varying rate depending upon the amount of temperature increase in the water through the solar panels. A higher flow rate of water being circulated through the panels if the temperature rise is higher.