The combined shore-thruster and energy storage converter system is a multi-purpose inverter system designed to operate in different applications. During sailing, manoeuvring and dynamic positioning, the system is used to drive the thruster motor as well as delivering power to the main switchboard. During shore time, the same switchboard is used to power the main switchboard with shore voltage. In case of high load demands, the energy can be taken from the storage system to avoid the start of additional generators. Furthermore, the system can deliver power to the main switchboard to provide a short time, non-diesel generator operation. The shore converter system supplies power to the main switchboard with shore voltage. The system is fully compatible with all types of shore breakers and complies with worldwide shore-grid supply regulations and restrictions. The shore converter can be designed as a standalone system or can be integrated into a hybrid system.