Conical solar stills: A review

The conical solar still (CSS) is an advanced solar distillation design featuring a cone-shaped glass cover for condensation. This innovative design offers several advantages over conventional solar stills, including reduced shading effects, a larger solar absorption area, uniform solar exposure, and an optimized space-to-productivity ratio. With a demonstrated productivity of 8.09 kg/m2, a production cost of 1.6 $/m3, and a CO2 mitigation of 44.47 tons, the CSS showcases superior energy, economic, and environmental performance compared to alternative designs. This paper provides a comprehensive evaluation of the advancements in CSS research, including various strategies to enhance efficiency. It offers an in-depth analysis of the thermal and design factors influencing CSS performance, encompassing both conventional and advanced configurations. Additionally, the study examines the economic and environmental aspects of CSSs, presenting a comparative analysis against traditional solar still designs. Practical guidance is also provided for the large-scale implementation of CSSs, emphasizing their feasibility and scalability. Finally, the paper identifies the limitations of current CSS technology and explores future opportunities for wider adoption and development. This extensive review serves as a clear roadmap for future designers, enabling the creation of commercial CSS systems that maximize productivity while remaining cost-effective and environmentally sustainable. © 2025 International Solar Energy Society