Large-scale implementation of greenhouse medium-regulated solar interfacial evaporation

Solar interfacial evaporation (SIE) offers a promising pathway for decentralized desalination, yet its practical deployment is hindered by pronounced air-side heat losses—particularly thermal radiation—which become increasingly severe at elevated operating temperatures and have received limited attention. Moreover, most SIE demonstrations remain at the centimetre scale, lacking scalable architectures and robust techno-economic validation. Here, we introduce a spectrally regulated SIE architecture integrating an ultrathin greenhouse medium (GHM) of silica aerogel microspheres onto a photo−/electro-thermal Janus membrane (GHM@H-CNT@PVDF). The GHM exhibits high solar transmittance (93.78%) while strongly suppressing mid-infrared thermal emission (≥35% blocking at <65 °C) and convective losses via nanopore confinement, effectively decoupling solar harvesting from heat dissipation. Under 1 sun illumination coupled with 10 V electrical input, the membrane achieves an evaporation rate of 7.3 kg·m⁻²·h⁻¹ with an energy-water efficiency of 90.35%. When scaled to a 1.21 m² outdoor platform and tested under natural sunlight without electrical heating, the system delivers a sustained freshwater production of 4.05 kg·d⁻¹ (peak 5.13 kg·d⁻¹) under natural sunlight. Techno-economic analysis reveals a levelized water cost of US$137.06 m⁻³, a payback period of 2.03 years against bottled water, and a net present value of US$567 with an internal rate of return of 13.3% over 15 years, substantially exceeding prevailing bank interest rates. By integrating spectral heat management, scalable fabrication, and rigorous economic assessment, this work bridges the gap between laboratory SIE innovations and practical, large-scale desalination, particularly in sunbelt arid regions facing severe water scarcity.