The operation of solar water purifier developed by Nimbkar Agricultural Research Institute (NARI) is shown in this video. This unit is for a family of four or five and cleans about 15 litters of water every day even in completely cloudy conditions. It does not remove dissolved solids but removes all coliforms and hence makes the water fit to drink. The details are given in; http://www.nariphaltan.org/swp.pdf
Thanks to interns Aniruddha Kane and Sanket Mane for shooting the clip and to Madhura Rajvanshi for doing an excellent job on editing it and providing subtitles and music.