Energetic and Exergetic Evaluation of Secondary Heating in Double Slope Solar Still

This study addresses the critical need for clean water access with growing global demand and limited freshwater resources. Using solar distillation, particularly using a double slope solar still, offers an effective solution to this challenge. By combining conventional solar desalination with auxiliary heating methods during low sunlight periods, continuous water evaporation is ensured, leading to enhanced water productivity. Results demonstrate that a heat flux of [Formula: see text] achieved the highest hourly yield of [Formula: see text] during nonsunshine hours, with cumulative yield reaching a maximum value of [Formula: see text]. Additionally, as water temperature rises, less energy is lost to convection, and system efficiency improves due to reduced irreversibility. Both exergy and energy efficiencies increased over time, with the highest energy and exergy efficiencies of 64.63 and 29.64%, respectively, at [Formula: see text]. This approach extends the usability of solar stills beyond sunshine hours, ensuring prolonged freshwater production and enhancing their usability as a viable water purification solution.