This refers to the act of using solar energy to heat water. Usually by means of putting a solar panel on a roof through which runs the water to be heated, which is then fed in a circuit to some form of insulated water storage for later use.
A solar hot water system consists of a collector, heat transfer circuit and hot water storage system. These can either be combined into one system or into 3 separate components depending on your exact needs. There are many different commercial suppliers.
See Solar Water heating, how it works and the options available article for more information.
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