Fault detection and interruption in connection with photovoltaic technologies are disclosed. An exemplary apparatus for interrupting a photovoltaic energy conversion system that employs a bipolar photovoltaic array includes a fault detector and interrupter configured to be coupled to the first and the second rails of the photovoltaic array, the fault detector and interrupter configured to detect a condition that requires interruption of the photovoltaic energy conversion system and open a PV tie to uncouple two PV arrays of the bipolar photovoltaic array, thereby decoupling the two PV arrays; and a controller configured to, after the PV tie is opened, open a plurality of main DC contactors thereby decoupling the bipolar photovoltaic array from a remainder portion of the energy conversion system.