Systems, methods, and apparatus for supplying AC power to an AC power grid from a DC power source, such as a photovoltaic (PV) array are disclosed. The systems and methods can include a converter coupled to the DC power source that provides DC power to a DC bus at a DC bus voltage. The systems and methods can further include an inverter coupled to the DC bus for converting the DC power of the DC bus to an output AC power. The systems and methods can further include a control system configured to regulate the DC bus voltage of the DC bus to operate at a variable DC bus voltage setpoint. The control system can adjust the DC bus voltage setpoint based at least in part on the DC bus voltage and the output AC current of the inverter.