This paper proposes a decentralized stand-alone photovoltaic (PV) system, which presents a set of advantages when compared to conventional stand-alone PV system. In the proposed system, the generated energy by the PV arrays is processed by multi-string MPPT step-up converters, which assure a maximum utilization of this energy. The storage system is designed in a decentralized configuration, enabling to achieve a reduction of maintenance cost of back-up system. Moreover, the output stage is composed by a multilevel dc-ac inverter, which enables higher efficiency, low distortion ac waveforms, low leakage currents and the use of low voltage rating semiconductor devices.