Although it has been shown that the overall
efficiency of a passive solar still is higher than
that of an active one due to the lower range of
operating temperatures [4--6], the concept is still
appealing in situations where the collectors are
already available. Recent works [7,8] indicate
that research is still active in the area, with more
emphasis on multi-effect desalination connected
to solar collectors. Another recent work [9] re-
ports that a productivity of 25 L/m2.d was reached
using such a system.