A tilted solar still has been studied in application to desalinate the
seawater. It essentially consists of a flat, blackened, tilted surfac
e with a transparent glazing as a covering. The seawater trickles down
as a thin film over the absorber and is heated by solar energy. The w
ater vapor that evaporates from the liquid film is condensed on the un
der side of the glass cover and the fresh water flows along the glass
surface by gravity into troughs. A simple expression is derived in thi
s paper by using approximations to estimate the mass of fresh water ev
aporated from the seawater as a function of climatic conditions and in
itial condition of the seawater through a simplified vapor pressure co
rrelation.