Abstract Over recent decades, the global demand for freshwater is increasing rapidly; however, the supply of freshwater is limited. Solar still (SS) is a valuable solar device that is used for converting the brackish and saline water into purified water. Several investigations depicted in literature have been performed, either experimentally or theoretically, on SS to assess its performance under different climatic and operational conditions. Apart from experimental studies, theoretical analysis is beneficial for evaluating the effectiveness of virtually designed SS. The theoretical analysis and simulation modeling of SSs can provide clear understanding on the mechanics, which may give directions on the design setup in experiments. In this review different theoretical approaches which have been used to assess the thermal performance of SS and exergy analysis of such devices are discussed. The reviewed studies indicate that the productivity of the SS depends on different external and internal operating parameters. In addition, the distillate quantity varies according to the design features and the related technical advancements of the SS. Our findings indicate that there are still few more parameters and design aspects to be considered while designing new SS. The objective of this paper is to highlight design methods so as to allow the researchers to optimize the SS for further development. Recommendations for further research have been also proposed.