PLATO (PLATeau Observatory) is the third-generation astronomical site-testing laboratory designed by the University of New South Wales. This facility is operating autonomously to collect both scientific and site-testing data from Dome A, the highest point on the Antarctic plateau, at an elevation of 4093m. We describe the power generation and management system of PLATO. Two redundant arrays of solar panels and a multiply-redundant set of small diesel engines are intended to provide 1-2kW of electrical power for a full year without refueling or other intervention. An environmental chamber has been constructed to study the high-altitude performance of the diesel engines, and suitable cold-starting procedures and engine lubrication techniques have been developed. PLATO's power system is an innovative solution with wide applicability to small astronomical facilities on the Antarctic plateau, offering minimum environmental impact and requiring minimal human intervention.