A CleanEnergyAuthority.com article explains the differences between two hybrid solar systems using photovoltaic cells to warm water: one by taking waste heat and transferring it to a building’s water heating system and the other a series of mirrors to concentrate the solar energy to one area of PV cells and a fluid heat transfer system. [www.cleanenergyauthority.com/solar-energy-resources/understanding-hybrid-pv-thermal-systems]
One residential system from EchoFirst uses conventional silicon PV modules. Heated air is collected via a fan system under the roof panels and moved though an energy transfer module. The ETM directs the sun’s thermal energy to the building’s hot water system. Excess heated air is used to heat the home if needed.
The other commercial system from Cogenra uses a series of mirrors, arranged in a parabolic trough to concentrate solar power on a strip of silicon PV cells. A fluid heat transfer mechanism behind the PV cells helps reduce the heat on them. It also provides hot water and can drive a chiller for a large building.