Water desalination using PV panels based on boiling and evaporation

Abstract

The annual share of water in Egypt has decreased to approximately 500 m3 per capita, while the annual water scarcity level is 1000 m3 per capita, which indicates that Egyptians are at a high risk of living. A domestic desalination unit based on solar energy was designed, built, and tested to solve this problem in remote areas that do not have access to fresh water or electricity but have access to salty water. The desalination unit has a new design that depends on boiling salty water using photovoltaic solar cells and then condensing the water vapor through a heat exchanger to obtain freshwater. This new design has not been implemented before and can compete with the solar stills used for domestic applications. The output of the developed unit was compared to those of passive and active solar stills that have been developed and built. The new desalination design produced almost the same amount of daily fresh water, 4 Liter/day, compared to the other solar stills (2–4.75 Liter/day), but the cost per unit volume of the new design, 31 $/m3, is less by 30% compared to the best performing solar still, 44.55 $/m3, which produces only 2 Liter/day. The price of the distilled water produced by the new design was 75% lower than the market price at the time of conducting the experiments. Converting a Solar still from a passive system, that is, operating only during sunlight, to an active system operating day and night improves the water productivity rate. However, this is not feasible because of the added accessories that increase the initial cost, consequently increasing the cost of desalination.