Solar distillation is the process of removing salts and other impurities using the energy of sun to get a pure water for drinking.
There are a range of solar technologies which will have their own impact to a lesser or greater degree. Solar photovoltaic technology relies on advanced manufacturing techniques in centralised factories making mass produced items. All this will have an environmental impact. However, once installed they have very little further impact.
Solar distillation is a more simple way to make use of solar energy but still requires certain materials to make the stills, such as glass and cement. Some designs reduce this impact by using earth to construct the main body of the solar still so the overall impact is minimal.