Design, Fabrication and Performance Study of a Solar Water Desalination (Single Slope Still)

Abstract

Access to clean water remains a critical global challenge, particularly in arid and remote regions where conventional desalination systems are costly and energy-intensive. To address this, the present study aims to develop an affordable and sustainable solar desalination unit capable of producing potable water using only solar energy. It is hypothesized that a simple single-slope solar still, optimized through effective thermal insulation, shallow basin design, and proper cover inclination, can significantly improve freshwater yield and overall efficiency. A prototype was designed, fabricated, and experimentally tested at outdoor conditions using a tempered-glass cover, a shallow, black-painted basin, a thermal isolator, a brine drain, and a channel used to collect condensates. The performance was evaluated in terms of temperature distribution, solar energy absorption, and hourly distillate output. The design was to increase thermal retention and evaporation speed based on the literature suggestions regarding the most effective cover angles, shallow water depth, and better insulation. Solar radiation, ambient/basin/glass temperatures, relative humidity, and production of hourly distillate were measured during various test days in August at different levels of irradiance. The daily freshwater yield was found to be at a maximum 1.15 L/day during test days with a maximum thermal efficiency of 39.7% with the highest performance achieved under strong solar irradiance and minimal cloud cover. Incident radiation and operating temperatures were found to have a strong dependence on productivity, and cloud cover and rainfall adversely affected it; the use of an insulation layer and a shallow basin enhanced performance as compared to traditional untreated designs. The modified unit exhibited improved performance with higher efficiency and competitive yield, while preserving a simple design, minimal maintenance, and zero fuel consumption. The findings confirm that a simple, fuel-free, and low-maintenance solar still can effectively provide potable water in resource-limited environments, supporting sustainable development goals related to clean water and renewable energy.