Experimental Investigation of Distillate output and Efficiency of Square and Rectangular Solar Stills under Identical Basin Area

The present research paper shows the square solar still (SSS) and rectangular solar still (RSS) of 1-meter square basin area were fabricated and tested simultaneously under the climate conditions of Patan, Gujarat, India during seven clear days of February 2025 for 10:00 AM to 05:00 PM of the day with variations in aspect ratio (based on different geometry) and 2 cm water depth consistently maintain inside the basin. The performance of the SSS and RSS was investigated in terms of hourly and cumulative distillate output, thermal efficiency and economic viability. Crucial parameters measured during the experiment included solar radiation intensity, ambient air temperature, basin water temperature, glass cover temperature and distillate output and percentage improvement in distillate output. The experimental findings highlight that the basin geometry based on aspect ratio (length to width ratio) plays vital role in distillate productivity pattern during the day. The square solar still perform better before 12:00 PM, whereas rectangular solar still perform better after 01: 00 PM due to the rectangular solar still with higher aspect ratio provide longer side align with better solar radiation distribution path (East to Waste) leads to higher basin water temperature and evaporation rate. Based on the seven-day experimental data, the rectangular solar still (RSS) produced 30.33% higher distillate yield than the square solar still (SSS). RSS improved the average instantaneous efficiency around 15.4% compared with the SSS. Additionally economic analysis further indicated a lower cost per litre of distillate yield for RSS.