A solar module includes one or more photovoltaic (PV) modules, a short-circuit switch connected in parallel with at least one of the one or PV modules, and a control unit connected in parallel with the short-circuit switch. The at least one of the one or more PV modules supplies electrical power to the control unit and is connectable via a first and a second module terminal to further solar modules to form a string. The control unit is configured to actuate the short-circuit switch depending on an insulation voltage dropped between a ground potential reference terminal of the solar module and one of the first and second module terminals.