Cooling of the condensation surface increases the production of purified water in solar distillation devices, also known as solar stills. However, most cooling methods are costly, complex and involve regular monitoring. Simple, easily operable and cheap cooling in solar stills can make it attractive for commercial adaptation at a large number of rural locations across the world. Here we demonstrate the increase in the area of the condensation surface as an effective way of increasing the production of purified water from the stills. Experiments were conducted inside the lab and under the sun. In the lab experiments, performed at a constant energy input of 625 W/m(2), the production of water increased by more than 65% with an increase in the area of the condensation surface by 7.5 times. In the experiments conducted under the sun, the production of water increased by more than 50% by using an additional area for condensation which is 7.5 times larger when compared with a reference still without an additional area of condensation. Further, by using a higher heat input, we show that the effect of increase in the area of the condensation surface by 6.5 times can increase the production of water by more than five times. We further demonstrate the effect of external cooling by decreasing the temperature of the condensation surface to almost 0 degrees C. The amount of water produced from the still was increased by more than eight times by maximizing cooling of the condensation surface. The results suggest that a solar still device with an increased area of condensation surface can be adapted as a cheap, easy to manufacture and easily operable device for a large number of people who are in need of drinking water. (C) 2015 Elsevier Ltd. All rights reserved.@en

Abstract Glass has been the preferable choice of material for its use as a condensation surface in solar distillation as it gives higher water production than other materials. However, it is not certain which property and subsequently which phenomena are responsible for higher production of water. In this paper, we study the influence of different condensation surfaces on the total water production in solar water distillation. From our results, we conclude that the contact angle is the most important parameter for choosing the material of condensation surface inside a solar water distiller. Subsequently, we also conclude that the reflection of solar irradiation from the surface is the most important phenomenon affecting the differences in water production from solar distillation.@en