Abstract: A zero-voltage-switching (ZVS) high-gain Boost converter with low voltage stress is proposed for the photovoltaic dc-module. The proposed converter is constructed by introducing an equivalent voltage source into the diode branch of the conventional Boost converter. This voltage source is composed of an inductor operated in bidirectional conduction mode, a synchronous rectifier and two capacitors. Hence, the voltage gain increases by (1+D) times (D is the duty cycle of main switch), while the voltage stress on the power components and the filter capacitors are decreased. Moreover, all active switches achieve the ZVS and the diode naturally turning off. In this paper, the working principle, the steady-state characteristics (including voltage gain, voltage stress and current stress) and the soft-switching realization conditions of the proposed converter are analyzed in detail, and then the parameter design is given. The correctness of the theoretical analysis is verified on a 250W/100kHz experimental prototype, which shows the maximum efficiency is up to 97.7%.