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,. 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.••••State-of-the-art designs of solar-driven hybrid energy units are summarized.••Overall performances and practical applications are highlighted.••Future perspectives and key challenges in this realm are discussed.Solar-drivenPhotoelectrodeIntegrated systemSelf-poweredTo date, fossil fuels still account for 80% of global energy consumption, readily leading to devastating global warming and climate change [1,2]. In this respect, the development and application of renewable energy has become increasingly urgent. Solar energy is one of the most promising renewable energy resources with ca. 23,000 TW of abundant energy storage each year, which, in earnest, fully meets the global energy consumption [3,4]. It is an infinite and effective energy form to harness huge application potentials owing to the affordable and sustainable feature.There has been a variety of solar energy utilization technologies explored by far, encompassing solar collectors, photovoltaic (PV) cells [5,6], solar heating systems etc. Amongst these, PV cells enable the direct conversion of solar energy into electricity showing soaring demands nowadays. However, solar energy is intermittent during day and night, and in turn, ordinary solar cells are difficult to meet the requirements for ready use, owing to the fact that they are merely able to convert solar energy yet unable to store it in time. Moreover, the light intensity is greatly affected by the space environment (sunny, rainy or cloudy conditions), which necessitates instant energy storage devices to regulate the output current. In view of these considerations, it is imperative to develop integrated systems that synergize the harvesting and storing of solar. On a basis of solar charging mechanism, the solar-driven integrated energy storage devices encompass two main categories of discrete connection (PV module charging) and direct incorporation (photoelectrode charging). Specifically, the discrete connection can be further subdivided into external wire and shared electrode hybridization. In this sectio.
