Patent ID: 8587906

Claim:
A photovoltaic (PV) power system comprising: a plurality of PV strings configured to generate a string output power responsive to received solar irradiation; a combiner box having a DC link therein connected to the plurality of PV strings, wherein the plurality of PV strings are connected to the DC link in a parallel arrangement; and a hybrid direct current (DC) contactor positioned in the combiner box and corresponding to each of the plurality of PV strings, each hybrid DC contactor comprising: main contacts movable between a closed position and an open position; a solid state switching unit positioned in parallel with the main contacts, the solid state switching unit including a semiconductor switch that, when turned on, diverts current away from the main contacts; and sensors configured to measure a voltage and current on the respective PV string; and a controller configured to: receive voltage and current data from respective sensors on each of the plurality of PV strings; detect a fault condition on a respective PV string based on the received voltage and current data; cause the main contacts of a respective hybrid DC contactor to remain closed on each PV string for which a fault condition is detected; and cause the main contacts of a respective hybrid DC contactor to open on each PV string for which no fault condition is detected, so as to clear the fault condition.