A power system for a stationary installation comprising a battery pack, a system component, and a system control unit. The batter pack has a plurality of removable battery modules. Each battery module has an internally controllable connection to a common power bus. The system component is controlled by a power controller unit having a connection to the common power bus. The system control unit is in communication with each of the battery modules and the power controller unit. The system control unit receives control inputs from an operator of the power system. The operator may be a human operator, an electronic operator unit, or a combination thereof.