Advances in pyramid solar stills: a comprehensive review of sustainable water desalination innovations

Abstract This study presents a comprehensive investigation into recent advancements in pyramid solar stills (PSS), focusing on how internal and external modifications have enhanced both performance and sustainability. The research critically examines the limitations of conventional solar stills in providing clean water and proposes innovative solutions to improve their productivity. Internal improvements like the integration of phase change materials (PCMs), Nanoparticles (e.g., TiO 2 and CNT-water Nanofluids), and energy storage materials (e.g., paraffin wax and quartz rock), meaningfully improve desalination output. PCM integration alone enhances water productivity by 35 to 101.5%, while Nanoparticle application assures an efficiency gains ranging between 6.1 to 54.4%. External modifications such as the integration of solar collectors, reflectors, and forced condensation systems, has increased water productivity. Statistically, the with water yield increases to 194% with a thermal efficiency up to 62.4%. Hybrid systems, that integrate multiple modifications, establish the greatest performance enhancements, delivering up to a 166% productivity growth when PCMs and reflectors are utilised in tandem. The results highlight that optimised PSS, developed through multidisciplinary approaches, offer a potential, sustainable, and cost-effective solution for freshwater production. However, a number of barriers linked to component integration and large-scale applications remain. More importantly, the associated findings of this review have stated a foundational framework to advance the design and operation of solar desalination technologies.