WATER HEATER CONTROL SYSTEM

The following are provided: a photovoltaic power generator (1) interconnected with a commercial power supply, an electrical load circuit (2) including a storage-type electric water heater (7) using power from the commercial power supply and generated power of the photovoltaic power generator (1), and a controller (4) limiting a water heating operation of the storage-type electric water heater (7) by stopping or suppressing the water heating operation of the storage-type electric water heater (7) when a power fee data for purchased power supplied to the electrical load circuit (2) from the commercial power supply exceeds a standard monetary amount. When the water heating operation by the storage-type water heater (7) is performed using photovoltaic power, and a purchase of power from the commercial power supply occurs due to a lowering of photovoltaic power because of temporary cloudiness and the like or due to an increase in in-home-use power because of unanticipated use of electric equipment and the like, so that a purchased-power fee is greater than or equal to prescribed value, the controller (4) suppresses or stops the water heating operation of the storage-type electric water heater (7).