Solar stills require a transparent enclosure with geometry that collects solar rays all day. Outside air is excluded from the enclosure to maintain a high relative humidity inside. A condenser is built into the surface of the enclosure, allowing outside air to cool the water vapor. Fresh vegetation or other hydrated material is placed inside the enclosure to collect he solar energy. Condensed water is provided a collection container shaded from of the sun light. A mechanism is required to open the still at night and replenish the hydrated materials, also a mechanism for removing condensed water day or night. The enclosure is hotter inside than outside all year when the sun is shining. Winter gets less sunshine, but also colder condenser.
The geometry of the solar still plays a major rule in the condensing process. Many researchers used water or air cooling for the transparency glass cover to increase the condensing process. Others, used refrigeration evaporator for cooling.