Abstract: The temperatures at the inlet and the outlet of a solar energy collector being flown through by water are detected and compared with a ramp signal to provide a pulse train in which the number of pulses represents the temperature differential. The ramp signal is produced at a repetition rate representing the water flow rate so that the tallied pulses represent the BTU's as absorbed by the collector.

Abstract: A solar heat collector having an enclosure, a first receptacle for a heated liquid medium, and a second receptacle for a cooled liquid medium. Heat transfer means within the enclosure provide for the transfer of heat either to or from a liquid medium therein. Additionally, the heating enclosure may include a closure member which is transparent to radiant energy from the sun. Means may be provided to move the closure member between an opened and a closed position in response to the intensity of radiant energy which impinges on the closure member. First means may then be provided to convey a liquid medium from the first receptacle through the heat transfer means and back to the first receptacle with the closure in a closed position. Also, second means may be provided to convey a liquid medium from the second receptacle through the heat transfer means and then back to the second receptacle with the closure member in an opened position.

Abstract: A system for transferring thermal energy from a solar energy collector to a storage tank by pumping water from the tank through the heat exchanger and back into the tank. Two temperature-sensitive thermistors sense respectively the temperature of the water as leaving the heat exchanger or as being held therein, and the temperature of the water in the tank or as leaving the tank; these thermistors are included in bridge circuits which provide control signals representing the collector and tank temperatures and the differences of these temperatures for controlling water circulation, collector heating and/or dumping of the water, for collecting thermal energy and for preventing the circulation from freezing or boiling.