An electrical power converter for converting power from a bipolar DC source to supply an AC load is disclosed. For one such embodiment the bipolar DC source is a photovoltaic array and the AC power is sourced into an electric power grid. The bipolar photovoltaic array has positive and negative voltage potentials with respect to earth ground. The converter is a utility interactive inverter which does not require an isolation transformer at the electric power grid interface. Embodiments of the invention include methods of detecting and interrupting DC ground faults in the photovoltaic array.