Abstract: A novel transformer-less high-gain three-port converter (TPC) is presented in this paper. It utilizes the buffer capacitor of the zero-voltage-switching (ZVS) dual-inductor high-gain two-port converter as a third port, which makes the front-end and rear-end inductors operated in the continuous and the discontinuous conduction modes respectively. Then the PWM+PFM hybrid modulation strategy are adopted to realize the maximum power point tracking control on the photovoltaic port and the constant voltage control on the load port simultaneously. The three ports of the proposed TPC share a common ground, realizing the bidirectional flow of the energy on the battery port. Besides, the proposed TPC retains the advantages of the original converter, such as continuous input current, reduced active switches (2), low voltage stress, high voltage gain, and soft-switching ability. In this paper, the working principle, steady-state characteristics, and control methods of the proposed TPC are analyzed in detail. The design process of the inductor parameters is also presented. The correctness of the theoretical analysis is verified by a 300W experimental prototype, which shows the maximum efficiency is 97.7%.