The paper proposes a new topology for photovoltaic dc/dc converter with high efficiency under wide input voltage range is proposed. Photovoltaic dc/dc is a very crucial part of power conditioning system(PCS). Considering that output characteristic of photovoltaic cell has wide voltage range, depending on the operating conditions of photovoltaic cell, the dc/dc converter also needs to have wide input voltage range to regulate the constant output voltage. In addition, a high rated voltage of power switch(MOSFET) for dc/dc converter is necessary in order to be compatible with the high maximum output voltage of photovoltaic cell's maximum output voltage. Also photovoltaic power conditioning system should have a high efficiency under operation condition. To satisfy PV PCS condition series connected non-isolated dc/dc converter topology is proposed. This paper examines the proposed topology employing four modules and shows that it dramatically enhances the energy efficiency from low load to high load condition by reducing the required power level for dc/dc converter by one-third of conventional dc/dc converter. A case of 25kW prototype as the PV dc/dc converter is introduced to experimentally verify the proposed topology.