Photovoltaic-multistage desalination of hypersaline waters for simultaneous electricity, water and salt harvesting via automatic rinsing

Passive solar multistage stiller with heat localization has shown great potential in wastewater purification and seawater desalination due to its ultrahigh solar-to-vapor conversion ability. However, achieving high water yield with long stability remains a great challenge because of the salt clog. Here, we demonstrated a photovoltaic-multistage stiller (PV-MS) with excellent salt-rejecting ability, even when dealing with hypersaline waters. The solar energy is converted to electricity and heat by a commercial photovoltaic panel and the waste heat subsequently drives the passive multistage stiller. The capillary wick and the crystalized salt at the edge of the wick form a siphon channel and the crystalized salt was rinsed intermittently by the siphon action, thereby avoiding salt clog. Thus, we achieved simultaneous electricity, water and salt collection in the integrated photovoltaic-thermal utilization system with long-term stability. Under one sun, the water yield of a five-stage stiller was about 1.17 kg m −2 h −1 with electricity output of 97 W m −2 and salt collection of 1.02 kg m −2 d −1 when desalinating hypersaline NaCl solution of 170 g/L. We envision that such a technology can help full use of solar energy in desalinating high-salinity waters with long term stability and is greatly promising at the water-energy nexus. We presented a photovoltaic-multistage stiller system with long term stability via manipulating salt crystallization for desalinating hypersaline waters and electricity generation. • Photovoltaic-multistage stiller (PV-MS) with excellent salt-rejecting ability was developed. • The crystalized salt was rinsed intermittently by the siphon action, thereby avoiding salt clog in stiller part. • Desalinating of hypersaline NaCl solution of 170 g/L with passive solar multistage stiller was demonstrated. • PV-MS could harvest electricity, water and salt simultaneously with high stability.