Abstract: A method for switching photovoltaic (PV) modules in a PV system to a safe state in the case of a hazard is described. Control units, each one associated with a corresponding one PV module, measure the voltage profile and/or the current of each associated PV module. Should the voltage of a PV module increase from the operating voltage to the idle voltage or, conversely, drop from the idle voltage to the operating voltage, or the current in the phase fall below a reference value, then the control unit associated with the PV module is activated. When activated, the PV module is either isolated from the phase on at least one connection side, with the result of at least one isolation location having a capacitor remaining connected in parallel with it, or a low-impedance load is connected in parallel to the PV module in a clocked fashion.