Working of solar still is based on simple scientific principle  of Evaporation  and condensation. Brackish or saline water is  filled in  still  basin  which  is painted black  at  the  bottom.  Solar radiation  received at the surface is absorbed effectively  at  by the  blacken surface and heat is transferred to the water  in  the basin.  Temperature of the water increases that increases rate  of evaporation.  Water vapor formed by evaporation rises  upward  and condenses  on  the  inner  surface of the  cover  glass  which  is relatively  cold.  Condensed  water  vapor  trickles  down  in  to throughs  from there it is collected in to the storage  container.

As  shown  in  the  picture. Solar  Still  consist  of  a  shallow triangular  basin  made up of Fiber Reinforced  Plastic(FRP).  (1) Bottom of the basin is usually painted black to absorb sun’s heat.Top of the basin is covered with Glass. (2) Titled fixed so as  to allow maximum transmission of solar radiation and enable condensed vapor to trickle down into throughs, built in channel in the still basin. The edges of of the glass is sealed with tar tape (3) so as to  make the basin airtight. Entire assembly is placed on a  stand structure  (4) made cup of MS. angles.  Outlet is connected  to  a storage ontainer through a pipe. (5) Provision is made to  change water  in  the stills. (6) A window is provided in  the  basin  to clean  the still basin from inside. (7) The still is  filled  with the brackish water in a thin layer.

The operation  of Solar Still is very simple  and  no  special skill is required for its operation and maintenance.