A photovoltaic system comprising at least one string of series-connected solar modules and adapted for individually disconnecting the solar modules and for safely initially connecting or reconnecting the disconnected solar modules to the string, comprising: a plurality of solar modules each one comprising a solar junction box, said solar junction boxes each having input-side positive and negative connection elements connected to the voltage-carrying conductors of the positive and negative poles of the associated solar module, and each having positive and negative output-side connection elements; wherein the solar modules are connected in series to form said string by means of a string line connected to said output-side positive and negative connection elements; wherein at least one of said solar junction boxes includes a safety circuit which comprises a short-circuiting switch between the output-side positive and negative connection elements and an isolating switch connected in series into the string, and which defines an operating state in which, with the isolating switch closed and the short-circuiting switch open, the solar power produced by the associated solar module is delivered through the solar junction box via the string line, and which defines a safe state in which, with the isolating switch open and the short-circuiting switch closed, the associated solar module is disconnected with respect to the connected string line by means of the safety circuit while the string line is nevertheless closed via the closed short-circuiting switch; a starter circuit connected to the string line and adapted to inject a starting current into the string line that is closed via the closed short-circuiting switch; wherein the safety circuit includes a current sensor and is adapted to be responsive to the starting current which is measured or detected by the current sensor and which flows through the string line that is closed by means of the short-circuiting switch, to automatically switch from the safe state into the operating state. a plurality of solar modules each one comprising a solar junction box, said solar junction boxes each having input-side positive and negative connection elements connected to the voltage-carrying conductors of the positive and negative poles of the associated solar module, and each having positive and negative output-side connection elements; wherein the solar modules are connected in series to form said string by means of a string line connected to said output-side positive and negative connection elements; wherein at least one of said solar junction boxes includes a safety circuit which comprises a short-circuiting switch between the output-side positive and negative connection elements and an isolating switch connected in series into the string, and which defines an operating state in which, with the isolating switch closed and the short-circuiting switch open, the solar power produced by the associated solar module is delivered through the solar junction box via the string line, and which defines a safe state in which, with the isolating switch open and the short-circuiting switch closed, the associated solar module is disconnected with respect to the connected string line by means of the safety circuit while the string line is nevertheless closed via the closed short-circuiting switch; wherein the solar modules are connected in series to form said string by means of a string line connected to said output-side positive and negative connection elements; wherein at least one of said solar junction boxes includes a safety circuit which comprises a short-circuiting switch between the output-side positive and negative connection elements and an isolating switch connected in series into the string, and which defines an operating state in which, with the isolating switch closed and the short-circuiting switch open, the solar power produced by the associated solar module is delivered through the solar junction box via the string line, and which defines a safe state in which, with the isolating switch open and the short-circuiting switch closed, the associated solar module is disconnected with respect to the connected string line by means of the safety circuit while the string line is nevertheless closed via the closed short-circuiting switch; a starter circuit connected to the string line and adapted to inject a starting current into the string line that is closed via the closed short-circuiting switch; wherein the safety circuit includes a current sensor and is adapted to be responsive to the starting current which is measured or detected by the current sensor and which flows through the string line that is closed by means of the short-circuiting switch, to automatically switch from the safe state into the operating state.