Solar stills SOLAR STILL A solar still is a very simple way for distilling water, powered by the heat of the sun, especially when distillation equipment is unavailable. A few basic types of solar stills are cone shaped, boxlike, and pit. For cone solar stills, impure water is inserted into the container, where it is evaporated by the sun through clear glass. The pure water vapor condenses on top and drips down to the side, where it is collected and removed. The most sophisticated of these are the box-shaped types.