An experimental investigation has been carried out into an attic-shaped solar still subject to natural conditions of Grashof numbers up to 1.7x10(8). The performance of the condensing covers was studied under two still orientations, east-west and north-south. A continuous recording of the main parameters affecting productivity was made, and significant thermal and distillate differences between the two condensing plates were found. A procedure to estimate each cover production in triangular solar stills as a function of still temperature and area fraction is proposed as an extension to the model proposed by Dunkle. Predictions made with this procedure show closeness to experimental data for the cases studied. (C) 2002 Elsevier Science Ltd. All rights reserved.