Since the late 1800s, there have been numerous attempts to develop economical systems for solar distillation. Initially these were simple single-effect, glass-covered stills. During the 1950s, as a result of support from the Office of Saline Water of the U.S. Department of the Interior, many efforts to develop a multiple-effect solar still were undertaken.

The University of Arizona developed a multiple-effect, humidification-cycle, solar-powered distillation unit that was installed in Puerto Penasco, Sonora, Mexico, in 1962. This unit operated successfully until 1965, when it was converted from solar energy to waste-thermal energy from a diesel-electric set. At the time of the discontinuation of its operation, it was the premise of the University of Arizona that the major obstacle to the development of an economical solar distillation system was inadequate low-cost materials that would provide a reasonable service life in a solar-energy application.

With the current renaissance of interest now in solar energy, it is hoped that the necessary long-term development programs will be established to improve the probability of successful solar-energy applications in the future. The paper presents some thoughts as to the direction in which future research should go.

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