¹ Mechanical Engineering Department, Madan Mohan Malaviya University of Technology, Gorakhpur-273010, Uttar Pradesh, India.

* Correspondence: dsme@mmmut.ac.in (Dheerandra Singh); vkme@mmmut.ac.in (Virendra Kumar)

Although solar desalination is a sustainable method of producing drinkable water, its poor productivity prevents it from being widely used. The current study combines geometric alteration with improved thermal energy storage and heat transfer to create a novel stepped-slope single basin solar still integrated with copper cylinders filled with silver-based nanofluid. Using mono nanofluids at various volume concentrations (0.01%, 0.03%, 0.05%, and 0.07%), the system's performance is experimentally examined and contrasted with a conventional solar still. To assess overall viability, a thorough 4E (energy, exergy, economic, and environmental) analysis is conducted. The optimum configuration with 0.07% silver nanofluid yields maximum energy efficiency (49.75%), exergy efficiency (3.46%), and freshwater productivity (2.81 kg/m²), according to the data. The suggested design also shows improved CO₂ mitigation, a shorter payback period, and lower costs. The results demonstrate the efficacy of combining stepped geometry with nanofluid-based heat storage, providing a viable and sustainable method for enhancing solar desalination systems and assisting clean water projects for sustainable development goals (SDG).