Reimagining Solar Desalination: A Critical Review of Innovations in Spherical Solar Still Design and Performance

Abstract

Abstract As climate change, rapid urbanization, and rising global demand continue to strain freshwater resources, the pursuit of sustainable and decentralized desalination solutions has become increasingly urgent. Solar‐powered water purification, particularly via passive systems, offers an environmentally sound and energy‐efficient pathway to address this challenge. Among the different solar still configurations, spherical designs (SPSS) stand out as a noteworthy advancement, based on their unique geometry that ensures uniform solar energy absorption, improved thermal efficiency, and a compact form suitable for off‐grid and remote applications.This review delivers an in‐depth and up‐to‐date examination of advancements in SPSS technology, focusing on recent integrations such as wick‐based evaporation systems, nanoparticle‐infused phase change materials (PCMs), reflective surfaces, internal baffles, and rotational mechanisms. Collectively, these improvements have led to significant enhancements in distillate output, with some designs achieving performance increases of up to 259% relative to traditional setups. By critically examining experimental research, modeling approaches, and techno‐economic evaluations, this review outlines the current landscape, identifies key limitations, and explores emerging strategies to enhance efficient and cost‐effective SPSS systems.The analysis underscores the role of SPSS as a promising and scalable method for generating clean water, particularly suited to sun‐rich regions facing resource constraints.