A hot water supply system includes: an obtainer that obtains (i) a first boiling amount for each of a plurality of water heaters and (ii) a reference power of a housing complex in which the plurality of water heaters are provided, the reference power being from a second time slot having a cheap electricity rate; a determiner that, when determining, based on the plurality of first boiling amounts, that a demand power of the housing complex will exceed the reference power if the plurality of water heaters start boiling simultaneously in the second time slot, determines, prior to the second time slot, a schedule that, of a first and second water heater, delays a start of boiling by the second water heater, for which the first boiling amount is lower; and a controller that controls boiling by the water heaters in the second time slot based on the schedule determined.

A hot water supply system includes: an obtainer that obtains (i) a first boiling amount for each of a plurality of water heaters and (ii) a reference power of a housing complex in which the plurality of water heaters are provided, the reference power being from a second time slot having a cheap electricity rate; a determiner that, when determining, based on the plurality of first boiling amounts, that a demand power of the housing complex will exceed the reference power if the plurality of water heaters start boiling simultaneously in the second time slot, determines, prior to the second time slot, a schedule that, of a first and second water heater, delays a start of boiling by the second water heater, for which the first boiling amount is lower; and a controller that controls boiling by the water heaters in the second time slot based on the schedule determined.