liquid-based solar collector
A liquid-based solar collector is a solar collector that uses sunlight to heat a liquid that is circulating in a 'solar loop'. The fluid in the solar loop may be water, an antifreeze mixture, thermal oil, or some other suitable liquid. The solar loop transfers the thermal energy from the collectors to a thermal storage tank. The appropriate type of collector to use depends on how hot the water must be and the local climate.
The most common liquid-based solar collectors are: