NOVELTY - The system has a watt-hour meter measurement data adjusting unit (1041) connected with multiple electricity generation devices via communication lines. The data adjusting unit calculates virtual generation-suppressed power amount to provide even burdens of the electricity generation devices, where the calculated power amount is independent of actual generation-suppressed power amounts. The data adjusting unit calculates the amount of power to be supplied by the electricity generation devices on a basis of virtual generation-suppressed power amounts.    USE - Solar power generation system for calculating power amount.    ADVANTAGE - The system calculates the amount of power to be supplied by customers on a basis of provisional generation-suppressed power amounts so that generation-suppressed power of the solar power generation system stabilizes the power system and allocates chances for selling power to customers with solar panels in an improved manner. The suppressed power amount is controlled and corrected so that differences between loss of chance for selling the power with respect to all solar power generation apparatuses and losses of chance for selling the power with respect to the individual solar power generation apparatuses is balanced, so that the losses of chance for selling the power with respect to the individual solar power generation apparatuses is evenly adjusted. The customer calculates the adjusted sold power amount on a basis of the sold power amount, where the sold power amount is a sum of the suppressed power amount and the amount of power passed through a pole-transformer, so that an amount of data transmitted from the customer to a power relay station is reduced.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for calculating power amount.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of a solar power generation system.    Power data relay station (104)    Power data aggregation center (105)    Solar panel (1011)    Domestic load (1013)    Watt-hour meter measurement data adjusting unit (1041)