Abstract: The invention relates to a method and an apparatus for performing a switching operation with the aid of a operation element (13). In order to avoid mechanical components, at least one light-emitting diode (14) is used as the operating element (13), and the voltage (U) on the at least one light-emitting diode (14) is measured in the switched-off state, and the switching operation is performed when the measured voltage (15) falls below a pregiven lower threshold (18) over a pregiven time period (19).

Abstract: The invention relates to a method and an apparatus for performing a switching operation with the aid of a operation element (13). In order to avoid mechanical components, at least one light-emitting diode (14) is used as the operating element (13), and the voltage (U) on the at least one light-emitting diode (14) is measured in the switched-off state, and the switching operation is performed when the measured voltage (15) falls below a pregiven lower threshold (18) over a pregiven time period (19).

Abstract: The invention relates to a device for protecting a photovoltaic plant (1) against rodent bite damage, wherein the photovoltaic plant (1) comprises several components, among them solar cells (2), a control unit (5), an inverter (7), an internal voltage supply means (13) and at least one microcontroller (9) which are interconnected via corresponding lines (3, 6, 8, 11). To provide such a device which offers an optimum protection against damage caused by bites and which entails as little maintenance and installation expenditures as possible, an ultrasonic transmitter (12) is provided for emitting an ultrasonic signal, and the ultrasonic transmitter (12) is connected to a microcontroller (9) of the photovoltaic plant (1) such that the ultrasonic signal emitted is controllable via the photovoltaic plant (1).

Abstract: The invention relates to a device for protecting a photovoltaic plant (1) against rodent bite damage, wherein the photovoltaic plant (1) comprises several components, among them solar cells (2), a control unit (5), an inverter (7), an internal voltage supply means (13) and at least one microcontroller (9) which are interconnected via corresponding lines (3, 6, 8, 11). To provide such a device which offers an optimum protection against damage caused by bites and which entails as little maintenance and installation expenditures as possible, an ultrasonic transmitter (12) is provided for emitting an ultrasonic signal, and the ultrasonic transmitter (12) is connected to a microcontroller (9) of the photovoltaic plant (1) such that the ultrasonic signal emitted is controllable via the photovoltaic plant (1).