In this paper, an analytical analysis and design of an active resonant snubber that is used for reducing the switching loss and switching stress of the dc-dc boost converter in grid-connected PV systems is proposed. The operation principle of the proposed active snubber is analyzed. A design consideration is developed according to the equations derived in various operation stages for determining the optimized values of soft commutation circuit components. The performance of the grid-connected PV system with the soft-switching dc-dc boost converter is demonstrated by simulation results to verify the operation analysis and the efficiency improvement. The results show that less switching loss and switching stress of the converter switch are obtained by the proposed active resonant scheme. The overall efficiency of an improved dc-dc boost converter is increased to about 94% from the value of 93% in its hard-switching PWM counterpart. ©2010 IEEE.