Synergistic solar-powered water-electricity generation: An integrated floating system on water

Abstract

The global pursuit of sustainable development faces two critical challenges: the scarcity of clean water and the growing energy crisis. The integration of solar-powered hybrid systems that harness the photovoltaic effect and passive steam generation has emerged as a crucial strategy. While several thermally-localized multi-stage solar stills have been developed, they predominantly rely on ground-mounted designs. Herein, we present a groundbreaking integration concept that combines a floating solar panel with a five-stage membrane distillation (MD) device, enabling simultaneous clean water and electricity generation on water surfaces. Positioned on the reverse side of the photovoltaic (PV) cell, the Janus membrane-involved multi-stage architecture of the MD device passively cools the PV cell, captures and repurposes the waste heat and manages vaporization enthalpy recycling. Our research highlights the importance of optimizing heat and mass transport within each stage, boosting the photoelectronic and photothermal conversion of the whole system. As a result, the integrated system achieves an impressive water production rate of 4.14 kg m−2 h−1 while simultaneously maintaining a high electricity generation efficiency of 16.4 % under 1 sun, therefore maximizing the total solar energy conversion. The clean water production rate of 11.6 kg m−2 day−1 places our system among the best-performing solar stills operating under natural sunlight. This integrated system sets a pioneering example of clean water and electricity co-generation with minimized carbon footprint, extending the applicability of ground-mounted solar conversion systems to water bodies.