US Patent 9148086 Photovoltaic DC sub-array control system and method

A photovoltaic energy conversion system, apparatus, and method for controlling DC sub-arrays of a photovoltaic array are disclosed. The method may include coupling each of N homerun branches from N sub-arrays to an inverter via N switches and monitoring current through each of the N homerun branches. A forward current through each of the N homerun branches is compared with a forward current threshold, and any backfeed current through any of the N homerun branches is compared with a backfeed current threshold. One or more of the N switches are opened in response to either the forward current exceeding the forward current threshold or the backfeed current exceeding a backfeed current threshold.