Valorizing reverse osmosis brine with solar energy: Modeling, simulation, and techno-economic comparison of PV/T- and PV-driven hybrid desalination systems incorporating membrane distillation

Seawater desalination provides an effective means to address water scarcity intensified by global warming and rising demand. When powered by solar energy, it can supply freshwater with minimal CO 2 emissions. This study develops and compares two fully solar-powered desalination systems, using modeling and simulations, aimed at increasing the Recovery Ratio (RR) and valorizing brine from a Reverse Osmosis (RO) unit. Both systems integrate thermal and electrical energy storage and incorporate Membrane Distillation (MD) units operating in series with RO. System A uses photovoltaic (PV) panels and solar thermal (ST) collectors, while System B combines hybrid photovoltaic/thermal (PV/T) panels with ST collectors. Simulations are performed under real meteorological conditions over one year in Almería, Spain. No previous work has assessed the techno-economic performance of solar-powered hybrid desalination systems with energy storage for higher RRs, nor compared traditional and hybrid solar collectors through dynamic annual simulations. The RO–MD configuration enhances RR and freshwater production relative to RO alone. System A increases output by 9.22%, and System B by 8.60%. RR rises from 40.50% to 44.23% in System A and from 42.04% to 45.66% in System B. PV/T integration in System B further improves performance by preheating seawater, reducing specific energy consumption (SEC), and increasing PV efficiency. This results in an 8.93% production gain and a 3.24% RR increase over System A. Levelized Cost of Water (LCOW) values are 5.01 and 5.27 USD/m 3 for Systems B and A, respectively, higher than conventional water costs but lower than many reported for solar-powered desalination systems. • Placing MD plants in series with a RO unit enhances overall freshwater production and increases the RR. • The solar‑powered RO‑MD system with energy storage achieves a lower LCOW than other solar‑powered desalination options. • A hybrid PV/T collector in an RO‑MD system enables higher freshwater output than a standard PV collector. • A hybrid PV/T collector in an RO‑MD system yields a lower LCOW than a conventional photovoltaic collector.