Enhancing Water Productivity of Solar Still Using Thermal Energy Storage Material and Flat Plate Solar Collector

In this research, the impact of integrating solar still with thermal energy storage material and flat plate solar collector (FPSC) on the freshwater productivity was experimentally investigated. The experiments were conducted on three types of similar-sized solar stills under climate conditions of Saudi Arabia. The first type was a conventional solar still (CSS), without any modifications. The second type was a modified solar still (MSS-1), CSS integrated with natural stones in the still basin. The third type was a modified solar still (MSS-2), CSS integrated with both natural stones and FPSC. Three types of natural stones with same quantity were selected and individually tested in the MSS-1 and MSS-2 simultaneously (each stone type on one day). The corresponding experimental results of MSS-1 showed a 11–32% increase in the daily freshwater yield, compared to CSS, indicating a minimal effect of natural stones utilization on the freshwater productivity. The MSS-2 showed a 155–183% increase in the daily freshwater yield, compared to CSS, indicating a significant effect of basin water heating on the freshwater productivity. The total dissolved solids (TDS) level was measured at 112 ppm, which complies with the permissible limits for drinking water quality standards. The economic analysis revealed that the cost to produce one liter of freshwater is 0.028, 0.022, and 0.027 $ from CSS, MSS-1, and MSS-2, respectively. Additionally, the benefit–cost ratio (BCR) analysis demonstrated the economic feasibility of the constructed solar still, with a BCR value of 2.1.