A power station system and a server thereof. The server includes a power-generation-amount calculator, a trade amount calculator, a balance calculator, and an information display controller. The power-generation-amount calculator proportionally distributes power generation amount information in accordance with power generation share number information, and adds a distribution value to owned power amount information of each member. The trade amount calculator subtracts a power sales amount from the owned power amount information. The balance calculator adds a power sales profit based on a change in the owned power amount information to balance information. The information display controller transmits the owned power amount information of the member and the balance information thereof to a computer terminal.