Experimental investigation of solar desalination in Algeria: Performance, economic feasibility, and climatic variability analysis of geothermal-integrated and glass-cooled solar stills

This study investigates the performance of three solar still configurations: Traditional Solar Still (TSS), Modified Solar Still 1 (MSS-1) with geothermal integration, and Modified Solar Still 2 (MSS-2) with a glass-cleaning mechanism, under three distinct weather conditions: clear and stable, intermittent solar and wind variability, and high wind influence with solar fluctuations. Experimental results show that MSS-1 outperformed the other systems, achieving the highest daily freshwater productivity of 4.17 L/m2, compared to 3.08 L/m2 for MSS-2 and 2.89 L/m2 for TSS. Under fluctuating solar conditions, MSS-1 recorded a peak energy efficiency of 43.67 %, surpassing MSS-2 (36.96 %) and TSS (32.48 %), with exergy efficiency of 4.24 %, compared to 1.41 % for MSS-2 and 1.39 % for TSS. The economic analysis revealed that MSS-1 had the lowest cost per liter (CPL) at $0.0091/L and a payback period of 70.67 days, outpacing TSS ($0.0101/L, 78.25 days) and MSS-2 ($0.0104/L, 73.24 days). Furthermore, incorporating real climatic data for 8760 h revealed that 75 % of the year is favorable, improving the accuracy of long-term productivity forecasts. MSS-1 achieved an annual water yield of 1522.37 L/m2, compared to 1055.37 L/m2 for TSS and 1127.57 L/m2 for MSS-2. These findings highlight the significance of considering real-world weather conditions in solar desalination design to improve efficiency, economic feasibility, and reliability.