Disconnection apparatus for a photovoltaic string, solar installation and operating method for a solar installation with a photovoltaic string

A solar installation comprising an inverter and a photovoltaic string comprising at least two series-connected solar modules, said photovoltaic string being connected to the inverter, wherein an apparatus is arranged between the solar modules, the apparatus comprising:

• a first terminal and a second terminal for a respectively assigned solar module of the photovoltaic string,
• a circuit breaker, a band-stop filter and a supply circuit arranged in a series circuit with respect to one another between the first and second terminals, wherein the supply circuit is configured to supply energy to the apparatus,
• a bandpass filter that bridges the circuit breaker and the band-stop filter in parallel, wherein the bandpass filter is configured to couple out a high-frequency control signal from the electrical connection, and
• a control unit configured to receive the high-frequency control signal and to operate the apparatus based on the high-frequency control signal,
• wherein a reverse current diode that is oppositely polarized relative to an operating current flow direction is connected in parallel with the circuit breaker or a partial series circuit comprising the circuit breaker and the band-stop filter.

An operating method for a solar installation comprising an inverter and a photovoltaic string comprising at least two series-connected solar modules, the photovoltaic string being connected to the inverter, an apparatus being arranged between the solar modules, the apparatus comprising:

• a first terminal and a second terminal for a respectively assigned solar module of the photovoltaic string,
• a circuit breaker, a band-stop filter and a supply circuit arranged in a series circuit with respect to one another between the first and second terminals, wherein the supply circuit is configured to supply energy to the apparatus,
• a bandpass filter that bridges the circuit breaker and the band-stop filter in parallel, wherein the bandpass filter is configured to couple out a high-frequency control signal from the electrical connection, and
• a control unit configured to receive the high-frequency control signal and to operate the apparatus based on the high-frequency control signal,
• wherein a reverse current diode that is oppositely polarized relative to an operating current flow direction is connected in parallel with the circuit breaker or a partial series circuit comprising the circuit breaker and the band-stop filter the operating method comprising:
• providing an initial energy supply for the apparatus with the circuit breaker open by impressing a current flow via the photovoltaic string and drawing energy from the impressed current flow via the string,
• transmitting a switch-on signal via the photovoltaic string, and
• closing the circuit breaker of the apparatus in reaction to the transmitted switch-on signal,
• wherein energy is supplied to the apparatus after the closing of the circuit breaker by energy being drawn from the current flow via the string,
• wherein impressing the current flow comprises impressing a reverse current via the string.