Solar hot water panels for heating a swimming pool Solar Hot Water refers to water heated by solar energy. Solar heating systems are generally composed of solar thermal collectors, a fluid system to move the heat from the collector to its point of usage, and a reservoir or tank for heat storage and subsequent use. The systems may be used to heat water for home or business use, for swimming pools, underfloor heating or as an energy input for space heating and cooling and industrial applications. In many climates, a solar heating system can provide a very high percentage (50% to 75%) of domestic hot water energy. In many northern European countries, combined hot water and space heating systems (solar combisystems) are used to provide 15 to 25% of home heating energy. In the southern regions of Africa like Zimbabwe, solar water heaters have been gaining popularity, thanks to the Austrian[1] and other EU funded projects that are promoting more environmentally friendly water heating solutions. Residential solar thermal installations can be subdivided into two kinds of systems: compact and pumped systems. Both typically include an auxiliary energy source (electric heating element or connection to a gas or fuel oil central heating system) that is activated when the water in the tank falls below a minimum temperature setting such as 50 °C. Hence, hot water is always available. The combination of solar hot water heating and using the back-up heat from a wood stove chimney to heat water[2] can enable a hot water system to work all year round in northern climates without the supplemental heat requirement of a solar hot water system being met with fossil fuels or electricity.