Experimental study of the performance of spherical solar stills using flat and corrugated circular absorbers with different techniques

Solar stills are a promising sustainable solution for addressing drinking water scarcity using renewable energy. This study investigates the enhancement of spherical solar stills by modifying absorption basin designs and applying advanced performance-improvement techniques. Replacing the traditional horizontal basin with a vertical black-painted basin and jute wicks increased productivity to 3500 mL/m²/day, representing a 52.4% improvement over the conventional still (2300 mL/m²/day). The addition of a rear reflector (RR) improved energy savings by 80% and increased productivity by 28%. Incorporating a solar tracking system (TS) further elevated productivity to 5388 mL/m²/day, a 45% improvement compared to using the basin and tracking system alone. The corrugated basin design achieved 4200 mL/m²/day. With the rear reflector, productivity rose by 44% and energy efficiency improved by 110%. Introducing the tracking system increased productivity and efficiency by 49% and 127.5%, respectively. The combined use of the reflector and tracking system produced a 52% rise in productivity and a 155.5% increase in energy efficiency. The best performance was recorded when paraffin wax was integrated with the corrugated basin. Under this configuration, productivity reached 8562 mL/m²/day, with a 185.5% increase in productivity and a 58% gain in efficiency. The maximum yield was 8.5 liters per day, accompanied by a net economic profit of $1124.48 and the shortest payback period of 0.361 years.