In at least some embodiments, a high-voltage drilling system includes a a power supply to output high-voltage power to an electrical conductor, a bit that extends a borehole based on the high-voltage power, and a hybrid drillstring that transports a fluid flow from the bit to convey detached formation material out of the borehole. At least part of the electrical conductor resides within the hybrid drillstring to convey power to the bit. The hybrid drillstring includes a coiled tubing section and a jointed pipe section.