A method for testing an electric system and an electric system comprising a first inverter (10) and one or more second inverters (11, 12, 1N), and control means (40) configured to start the first inverter (10), provide and sustain with the first inverter (10) an AC voltage of a predetermined magnitude and a predetermined frequency at an AC output of the first inverter, start at least one second inverter (11, 12, 1N), and supply with the first inverter (10) reactive power to the started at least one second inverter (11, 12, 1N).