This paper describes a simulation model that reproduces the performance of parabolic trough solar thermal power plants with a thermal storage system. The aim of this model is to facilitate the prediction of the electricity output of these plants during the various stages of their planning, design, construction and operation. Model results for a 50 MW(e) power plant are presented and compared to real data from an equivalent power plant currently operated by the ACS Industrial Group in Spain. (C) 2011 Elsevier Ltd. All rights reserved.