A storage heater is an electrical appliance which stores heat at a time when base load electricity is available at a low price, usually during the night, and releases it during the day. Heat is usually stored in clay bricks or other ceramic material because of its low cost and high specific heat capacity.
Storage heaters are usually used in conjunction with a two-tariff electricity meter which records separately the electricity used during the off-peak period so that it can be billed at a lower rate. In order to derive any benefit from a storage heater, the house must be on a special electricity tariff.