Demand of fresh water is rising continuously because of increase in population. This has created an undue burden on limited reserves of fresh water. Desalination is one of the methods which works on the principle of natural evaporation and condensation and can be used to treat ocean water into fresh water. One of the sustainable ways of converting saline water into fresh water is through the use of direct solar desalination technology. This review article analyses active solar still and passive solar still and its advancements in terms of productivity and efficiency to produce fresh water. This paper depicts a detailed comparative analysis of various direct solar desalination processes in terms of various performance parameters. Modifications and innovations in the design of solar still were discussed in detail, resulting in maximizing the productivity and efficiency, reduction in capital cost and easy in installation. Advancement in solar desalination technique through the use of Phase change material (PCM) and novel nanocrystals to make solar stills more productive and efficient was discussed in detail. Additionally, a detailed comparison of modified solar still on the basis of various performance parameters like location, water temperature, daily solar radiation level, daily yield, angle of tilt, productivity and efficiency was presented. Effect of using reflectors, concentrators and modified absorber area on various performance parameters of solar still was also investigated. Authors also presented a brief economic analysis of various desalination methods in terms of cost of water ($)/L. At last, authors presented some recommendations based on this review for future work on solar water desalination process.

由于人口增加，对淡水的需求持续增长。这给有限的淡水储备造成了不适当的负担。脱盐是根据自然蒸发和冷凝原理工作的方法之一，可用于将海水处理成淡水。将盐水转化为淡水的可持续方法之一是使用直接太阳能淡化技术。这篇综述文章分析了主动式太阳能蒸馏器和被动式太阳能蒸馏器及其在生产淡水的生产率和效率方面的进步。本文根据各种性能参数，对各种直接太阳能淡化工艺进行了详细的比较分析。仍然详细讨论了太阳能设计的修改和创新，从而最大限度地提高了生产率和效率，降低了投资成本，并且易于安装。详细讨论了通过使用相变材料（PCM）和新型纳米晶体使太阳能蒸馏器更高效和生产而在太阳能脱盐技术方面的进展。此外，还介绍了基于各种性能参数（如位置，水温，日太阳辐射水平，日产量，倾斜角，生产率和效率）的改性太阳能蒸馏器的详细比较。还研究了使用反射器，聚光器和改进的吸收器面积对太阳能蒸馏器各种性能参数的影响。作者还根据水成本（$）/ L简要介绍了各种脱盐方法的经济分析。最后，