Document Type : Review Paper


1 Mechanical Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.

2 Control and Systems Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.

3 Mechanical Engineering Dept., Faculty of Engineering, Kafrelsheikh University, Kafrelsheikh, Egypt.


This comprehensive research paper reviews the latest techniques to enhance the productivity of double-slope solar stills by providing quantitative data on key research outcomes. With the global water scarcity crisis and the need for effective desalination technology, this study focuses on solar-based desalination techniques and their specific application in double-slope solar stills. This paper offers a comprehensive and quantitative analysis of heat addition methods in double-slope solar stills by examining published research findings, providing valuable insights for researchers and practitioners. The study reveals significant improvements in productivity through various modifications. Evaporation enhancement, heat transfer enhancement, and condensation enhancement have proven to be highly effective, resulting in substantial increases in water production. The use of thermoelectric modules in double-slope solar stills has shown a remarkable 250% increase in water production by heating the water in the basin, which enhances evaporation rates and condensation on the glass cover. Moreover, the integration of Evacuated Tube Collectors (ETCs) has demonstrated a notable improvement in double-slope solar stills' life cycle conversion efficiency. The system incorporating ETCs achieved an impressive 59.42% higher efficiency than a system without ETCs, primarily due to the enhanced thermal input provided by ETCs to the solar still's basin. Another significant finding is the six-fold increase in water production achieved by implementing the double-slope solar still with a PV heater (CSSPVH) compared to conventional solar stills (CSS). This substantial improvement positions the CSSPVH design as a highly efficient solution for long-term potable water generation. Furthermore, adding a water heater to the base tank of a solar still has been found to raise water temperature quickly, resulting in a significant boost in production by approximately 370%. However, it is important to note that productivity decreases with increasing wind speed. Even with an outer cooling fan to cool the solar still's glass surface, productivity is reduced by 4% and 8% for wind speeds of 7 m/s and 9 m/s, respectively.

Graphical Abstract


  • Enhanced modifications were made to double-slope solar stills to raise water output significantly.
  • Solar stills are suitable for various climates, including hot and humid ones.
  • Thermoelectric modules led to 1032.5 L/m2.year water production increase.
  • Evacuated Tube Collectors (ETCs) and multi-scale heat exchangers substantially improved efficiency.


Main Subjects

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