Another well-known solar technology is rooftop solar water heating.

It generally works by focusing the warm rays of the sun to heat water.

In active systems, water is heated by the sun in a variety of ways, depending on if the system is a direct system (better for non-freezing climates) or a closed-loop/indirect system (which can be used in freezing climates). Water is either directly heated, or a non-freezing liquid is heated then passed through a heat exchanger where it heats the water, which then transferred to a tank where the hot water is either used immediately, or stored for later use.

Solar water heating is a common form of solar technology, especially in warmer climates and equatorial regions where the energy available from the sun is most intense. However, with a little engineering and non-freezing heat-transfer fluids, solar water heating can be effectively used in any climate. South-facing and unshaded roofs are most effective for this technology.

 

Resources:

Project Drawdown

Department of Energy

Whole Building Design Guide (WBDG)

ENERGY STAR