Many types of sports clubs use solar energy to heat water for showering. Because this type of application requires large volumes of hot water, in a short time span, for example thirty sweaty soccer stars requiring thirty showers after a match and that volume of water will require a day or two to heat up to the required temperature , it is wise to install a large numbe of tubes and a large hot water cylinder, to store surplus hot water. Any excess hot water can be used to provide background heating to the officials changing rooms!