Thermal Analysis, Experimental Validation, and Performance Evaluation of a Single Slope Passive Solar Desalination Unit for Bahrain

Bahrain relies heavily on centralized seawater desalination, driven by minimal rainfall (70–80mm/year), high evaporation (>2,000 mm/year), and depleted groundwater, while conventional reverse osmosis and multi-stage-flash systems demand 3–22kWh/m³ and grid scale infrastructure. This paper presents the thermal design, analytical modeling, experimental validation and performance evaluation of a passive single slope solar still adapted to Bahrain's climate. Using energy balance equations and Dunkle's correlation for internal heat and mass transfer, hourly simulation under representative summer conditions (G=850W/m², Ta = 40°C, Vw=3m/s) predicts a baseline productivity of 2.05L/m²/day at 34% thermal efficiency. Experimental measurements obtained from a fabricated prototype showed good agreement with the model. Sensitivity analyses across water depth (0.02–0.15m) and glass tilt (15°–35°) identify design tradeoffs, and three enhancement strategies; latent heat recovery, basin fins, and an external air cooled condenser raise productivity to 2.93L/m²/day (+43%) in combination. The design projects 720L/m²/year at a fabrication cost of ~68BHD, supporting a viable commercial deployment pathway aligned with Bahrain Vision 2030 and the United Nations Sustainable Development Goals (SDGs) 6 (Clean Water and Sanitation), 7 (Affordable and Clean Energy), 9 (Industry, Innovation and Infrastructure), and 13 (Climate Action).