The disclosure describes a method for operating an energy supply installation which is connected to an AC supply grid via a transformer, and exchanges electrical power with the AC supply grid via the transformer. The transformer is connected on a first side to the AC supply grid and on a second side to an AC installation grid of the energy supply installation, wherein the energy supply installation has at least one inverter which exchanges electrical power between a DC unit on the DC side of the inverter and the AC installation grid on the AC side of the inverter. The method includes receiving at least one parameter of the power conversion of the at least one inverter by an installation controller, determining a setpoint AC voltage for the AC installation grid by the installation controller according to the parameter, transmitting the setpoint AC voltage to the transformer.