Integration of solar PV, fuel cell, and hydrogen storage systems for sustainable desalination: techno-economic and multi-criteria decision-making analysis

• Hybrid PV-fuel cell-hydrogen systems achieve 99–100 % desalination reliability across four coastal locations. • Fuel cell capacity factors remain below 1% across all sites suggesting hydrogen over-specification. • Hydrogen production consumes 5504–8123 L/yr water creating water-energy nexus trade-offs. • Multi-criteria optimization reveals NOx emissions and fuel cell production dominate system ranking. • Alexandra Bay optimal with $0.242/kWh energy cost and lowest environmental impact. Water scarcity affects approximately 2.1 billion people globally, with remote communities in sub-Saharan Africa particularly vulnerable to inadequate portable water access and related health challenges. While renewable energy integration with desalination has gained attention, comprehensive multi-criteria assessments across multiple coastal locations remain limited. This study presents a techno-economic and multi-criteria optimization of solar PV/fuel cell/battery/electrolyzer/hydrogen storage systems for powering seawater desalination plants in four South African coastal provinces. Using the Hybrid Optimization Model for Electric Renewables (HOMER Pro) software, system sizing, economic analysis, reliability assessment, and environmental impact evaluation were conducted through energy-balance simulations, followed by entropy-weighted multi-criteria decision-making analysis using WSM, WASPAS, EDAS, and ARAS methods. The results show that Alexandra Bay emerged as the optimal location, achieving the lowest total net present cost ($122,742), levelized cost of energy ($0.242/kWh), levelized cost of water ($0.796/m 3 ), highest essential load reliability (100 %), and minimal environmental impact (3.47 kg/yr NO x emissions, 5,504 L/yr water consumption). However, fuel cell capacity factors across all locations remained extremely low (0.38–0.84 %), with hydrogen production significantly exceeding consumption, suggesting that battery storage alone may suffice for this application scale. Overall, the results demonstrate that solar resource availability and dispatch strategy selection significantly influence system performance, providing a robust framework for sustainable water-energy nexus solutions in water-scarce coastal regions. Finally, the economic viability of hydrogen-integrated desalination systems will be increased if the capital costs associated with fuel cells and hydrogen storage are reduced by 60–80 % below current values.