Patent ID: 8804390

Claim:
A method of connecting an AC output of a transformerless inverter of a solar power plant to an internal AC power grid at an input side of a galvanic isolation, while at least one photovoltaic generator is connected to a DC input of the inverter, while an external AC power grid is present at an output side of the galvanic isolation and while an offset voltage for shifting a potential center point of the at least one photovoltaic generator with regard to earth potential is applied in a first direction, the method comprising: synchronizing the inverter with the internal AC power grid, while all current-carrying lines of the AC output of the inverter are still galvanically separated from the internal AC power grid; moving a potential center point of the AC output of the inverter, which is not yet shifted by the offset voltage, in the first direction by connecting a current-carrying line of the DC input of the inverter to earth potential, while all current-carrying lines of the AC output of the inverter are still galvanically separated from the internal AC power grid and while a potential center point of the internal AC power grid is shifted by the offset voltage; and galvanically connecting the current-carrying lines of the AC output of the synchronized inverter to the internal AC power grid after synchronizing the inverter and moving the potential center point of the AC output of the inverter.