The earth receives more energy from the sun in just one hour than is used worldwide in a whole year. This energy is free and the technology to capture it is readily available and easy to use. Solar thermal technology is typically used to supply hot water to a building, reducing the use of fossil fuels and therefore, the buildings environmental impact.

Solar water heating uses the sun to heat a liquid that is pumped through a panel of pipes, which are normally located on the buildings roof. In the most common systems this liquid then flows through a coil in a hot water cylinder where the heat is transferred to the water in the hot water system. Most systems have a small pump that moves the heated liquid around the system.

Solar water heating should not be confused with photovoltaic systems which make electricity.