Currently, more decoupled photovoltaic (PV) systems demonstrate significant advantages in terms of efficiency increasing the competitiveness of the produced energy. This trend has been performed specifically in string and multistring configurations, where DC-DC converters are used to perform more distributed maximum power point tracking (MPPT). However, high variability in PV sources requires wide input voltage range capacity for the DC-DC converter affecting the efficiency of a classical DC-DC converter topology. Serial partial power converters (S-PPC) have drawn the attention in the last years due to its high efficiency processing only a fraction of the total power. In this paper it is proposed a two-stage approach for high efficiency step-up/down performance for a partial power conversion. Compared with the Type 1 or Type 2 step-up/down S-PPC, the proposed converter can operates with wider range of operation and presents higher partiality over the full operating range, leading to a higher global efficiency. Simulations are provided to verify the validity of the proposed two stage approach.