A circuit with series-connected solar modules separated into a first and second substring, wherein each substring includes a first and a second terminal, and a solar inverter configured to supply electrical energy from the solar modules to an AC power grid. The circuit includes a first switch coupled to the first terminal of the first substring to a first power cable of the inverter, and a second switch coupled to the second terminal of the first substring to a first terminal of the second substring at a center point, thereby coupling the first and second substrings to form at least one string. The circuit further includes a third switch couple to second terminal of the second substring, and a shared actuator to open the first switch, second switch, and third switch if a current between the center point and a circuit ground exceeds a threshold value.