Some embodiments of the inventive subject matter provide a system including a plurality of power supply units having AC inputs configured to be coupled to an AC power source and AC outputs coupled to respective first busses. Each of the power supply units includes an uninterruptible power supply (UPS) having an output configured to be coupled to the AC output of the power supply unit, a first switch configured to selectively couple the AC input to the AC output of the power supply unit, and a second switch configured to selectively couple the AC output of the power supply unit to a second bus. The system may further include at least one control circuit configured to control first and second ones of the power supply units to enable the first one of the power supply units to provide power to the first bus coupled to the second power supply unit from the first power supply unit via the second bus.