Enhanced solar desalination performance via integrated interfacial heating and PV-assisted water circulation in a modified single-slope solar still

Abstract

Freshwater scarcity remains a critical global challenge, particularly in remote and coastal regions where access to clean water is limited and conventional desalination methods are energy-intensive and costly. Addressing this issue requires sustainable, decentralized, and cost-effective water-purification technologies. This study aims to enhance the performance of single-slope solar stills (SSSS), which often suffer from low productivity and thermal inefficiency, despite their design simplicity and affordability. To overcome these limitations, a modified SSSS that integrates interfacial heating (IH) and photovoltaic (PV)-assisted seawater circulation was developed and evaluated. The system incorporates a floating absorber made of coconut-shell charcoal and a solar-powered water heater to improve the evaporation rates and energy conversion efficiency. The objective of this study is to systematically investigate the thermal behavior, freshwater yield, and energy efficiency of the integrated SSSS-IH system and compare it with that of the conventional configuration. Experimental results show that the integrated system achieved an average daily freshwater productivity of 7.45 L·m⁻² and energy efficiency of 28.68 %, compared to 3.26 L·m⁻² and 13.69 % for the unmodified system. Maximum productivity reached 9.31 L·m⁻²/day. Water quality analysis confirmed that the distilled water met clean water standards, reducing the salinity from 32,300 ppm to below 60 ppm. These findings highlight the effectiveness of the system in improving freshwater yield and energy efficiency and offer a practical solution for sustainable desalination in water-scarce regions.