A power supply system includes a power generation facility configured to supply power to a consumer and a server configured to communicate with the facility. The facility includes a fuel cell configured to generate, using fuel gas supplied via a supply path of the fuel gas to the consumer, power to be supplied to the consumer, and a measurement unit configured to measure a supply amount of the fuel gas used for the power generation. The server includes an acquisition unit configured to acquire information concerning a supply amount of the fuel gas supplied to the consumer, and a specifying unit configured to specify, based on a measurement result of the measurement unit received from the facility and the information, a supply amount of the fuel gas not used for the power generation in the supply amount of the fuel gas supplied to the consumer.