The present work describes the analysis, modeling and control of a Boost-Buck power inverter used as a DC-DC and DC-AC power conditioning stage for autonomous photovoltaic (PV) systems. To maximize the steady-state input-output energy transfer ratio a backstepping controller is designed to produce balanced three phase voltage, extract and transfer a maximum Power extracted from photovoltaic generator. The achievement of the DC-AC conversion and the efficient PV's energy extraction are validated with simulation results.