The renewable energy sources, such as fuel cells, photovoltaic (PV) panels, and battery pack, produce a low and variable dc output voltage, and their power generation efficiency and lifespan are affected by the output current ripple. Therefore, a high-gain converter with continuous input current is required as an interface to satisfy the requirements of front-end current ripple rate and rear-end voltage level. To address the common issue of insufficient boosting ability in the existing non-isolated high-gain converter, by combining the quadratic boosting, switched-inductor and charge pump technologies, a new triple-inductor single-switch high-gain boost converter is proposed in this paper. A 200W/50kHz experimental prototype is designed and manufactured to verify its feasibility. The experimental results show that the proposed converter can achieve the ultra-high voltage gain of 2/(1-D)2, which is much higher than the existing schemes. Moreover, it has the advantages of continuous input current, common ground, small amount of devices and ease of control.