Solar-driven integrated energy systems: State of the art and challenges

Solar energy is one of the most popular clean energy resources that can be fully utilized to date. The growing energy demand of modern society has spurred the technological advance of solar cells affording high power conversion efficiency and low-cost aspects. Nevertheless, the intrinsically intermittent nature and fluctuating output power of solar irradiation greatly restrain the practical uses of solar cells, especially in the scenarios of smart consumer electronics, electrical vehicles and hydrogen fuel production. With a collection of attractive features including favorable stability, durability and practicability, solar-driven integrated energy system that synergizes energy harvesting and storage offer a viable solution. This review summarizes the state-of-the-art knowledge in designing concepts, integrated configurations and overall performances of different types of solar-driven hybrid energy units. Particular attentions are paid to highlighting the practical application sectors enabled by those integrated energy systems. Future perspectives and key challenges in this emerging field are also covered at the end.