A solar still of double exposure is theoretically analyzed and experimentally tested. It is compared experimentally with other identical stills without modification (ordinary L-type) during a complete year. The concept of planer reflectors is introduced in this modification. It is found theoretically that the double exposure still gained much more daily energy than that of the ordinary one in winter and summer. Experimentally, it is found that the double exposure solar still has 82.6% more daily yield than that of the ordinary one in winter time, and about 22% in summer time. (C) 2002 Elsevier Science Ltd. All rights reserved.