Solar stills with porous absorber materials: a systematic review of design modifications and performance enhancements

Low productivity remains a major challenge limiting solar still adoption as a potential solution to the freshwater crisis. This systematic review covers the whole picture of the influence of porous materials in improving the performance of solar stills either by design adjustments or by added systems. According to key researches, porous materials, including black sponge rubber, carbon-impregnated foam, nanocoated absorber, etc., greatly enhance efficiency due to a large evaporation surface area, thermal storage capacity, and light absorbed. As an example, 15–40% of productivity was improved using floating perforated with black aluminum plates, whereas the carbon fiber/nanomaterials-modified epoxy composite had a yield improvement of 109%. The performance was further improved by structural innovations such as corrugated absorbers and rotating wick belts, and there were some designs that could produce up to 52.54% more. The efficiency increased by a maximum of 74.11% with hybrid systems that incorporate porous media with a combination of a phase change material (PCM) or with choices (solar collectors). Still, there are problems with the duration of materials and price, as well as the ability to scale. The review determines that porous materials used in conjunction with other structurally considered changes will result in a significant potential to maximize the productivity of the solar stills, but there is still a need to define or report on the limitations involved in the application of porous materials to the desired application since this will involve a route to economic viability.