In a discharge process of the solid body actuator (2), a current that discharges the solid body actuator (2) loaded with electrical energy is detected. A switching element (6) is switched from an open position to a closed position to short circuit the solid body actuator (2) for removal of electrical energy from the solid body actuator (2) through the switching element (6) depending on the current falling below a threshold of the current, wherein the magnitude of the threshold is specified.