In this study, we describe the constructal-theory search for the geometry of a solar chimney. The objective is to increase the power production over the area occupied by the plant. The ratio height/radius, maximum mass flow rate and maximum power under the constraints of a fixed area and volume are determined. We find that the power generated per unit of land area is proportional to the length scale of the power plant. The analysis is validated by a detailed mathematical model. Pressure losses are reported in terms of the dimensionless length scale of the system, and are illustrated graphically. They indicate that the pressure drop at the collector inlet and at the transition section between the collector and chimney are negligible, and the friction loss in the collector can be neglected when the svelteness (Sv) of the entire flow architecture is greater than approximately 6. (C) 2009 Elsevier Ltd. All rights reserved.