Enhanced desalination using double‐slope solar stills: A systematic comparison of slope materials and spacing configurations

Abstract Solar stills represent a promising passive desalination technique for freshwater generation; nevertheless, their practical implementation is constrained by poor productivity and thermal efficiency. This study examines the impact of glazing material combinations and inter‐layer spacing on the efficacy of a double‐slope solar still through experimental investigation. Four glazing configurations, glass‐acrylic, acrylic‐glass, double glass, and double acrylic were methodically assessed under uniform outdoor climatic circumstances. The initial comparison indicated that the double‐glass arrangement exhibited enhanced thermal performance, which was then refined by adjusting the inter‐glass spacing to 4 mm, 8 mm, and 15 mm. Temperature distribution, freshwater yield, energy efficiency, and exergy efficiency were empirically assessed and analyzed. The findings indicated that the double‐glass arrangement with 4 mm spacing produced the maximum daily freshwater yield of 510 mL, accompanied by an average solar intensity of 642 W/m 2 , an energy efficiency of 27.67%, and an exergy efficiency of 1.42%. The higher performance is due to superior heat retention and efficient condensation properties. The results validate that optimized double‐glass glazing using limited spacing offers a straightforward, economical, and scalable approach to improving solar still productivity, rendering it appropriate for decentralized freshwater generation in arid areas.