Single-phase DC/AC converters require large electrolytic capacitors to reduce the DC bus voltage ripples at twice the grid frequency. In this paper, a boost-type power decoupling circuit is adopted to absorb the low frequency ripple, and allow the use of film capacitors for long life-time as required by the photovoltaic power conversion system. Inevitably, the operation of the boost-type power decoupler reduces the energy conversion efficiency. To address this concern, this paper proposes the partial power decoupling technique to improve the operating efficiency over a wide power output range. To validate the proposed technique, experimental test results are given to validate its improvement in conversion efficiency. The European efficiency measurement is also provided.