A power conversion system includes: a storage battery; a first power conversion device configured to implement grid-connection operation with an electric power grid, converting electric power of the storage battery, outputting converted power to a connection point between load equipment and the electric power grid to supply electric power to the load equipment; and a controller transmitting a load adjusting signal to a load control part in the load equipment for reducing electric power supply to the load equipment if a state of the storage battery matches a remaining power shortage condition which is set in advance, during stand-alone operation in which the electric power grid is disconnected from the first power conversion device.