This paper analyzes the influence of operational strategies on the performance of parabolic trough (PT) solar power plants with the aid of SimulCET a computer program for the simulation of the energy behavior of PT plants developed by the National Renewable Energy Centre of Spain (CENER). SimulCET uses state of the art techniques to simulate solar energy absorption and others energy conversion processes that take place in a PT plant. The simulation of these energy conversion processes is based on both empirical and physically derived expressions and produces highly accurate electricity generation estimates. The holistic approach adopted in SimulCET to carry out the analysis of PT solar power plants makes this program a very effective tool in optimizing the operation of such plants. Furthermore, SimulCET's capabilities for simulating the operation of gas boilers make it possible to compare different operational strategies scenarios, and enable the testing of new hybrid plants concepts. To assess the validity of the results generated by SimulCET, these results were compared with current experimental data. The comparison showed good agreement among daily averaged estimates and the corresponding measured energy values. The comparison of SimulCET daily estimations against twelve reference days of measured data showed a mean deviation of 3.14% in terms of daily total gross electricity production. This paper focuses on the simulation and analysis of different PT plant operational strategies to explore the consequences and side effects of the way the fossil fuel is used, which have been seldom analyzed up to now, although they may significantly affect the long term performance of the plant. Four different operational strategies were compared. In all of them, the yearly amount of gas used was the maximum allowed for a solar PT power plant to be considered eligible to receive the benefits of the Spanish feed-in tariff legislation. Differences in gross electric energy output larger than 10% and differences in yearly gas consumption of up to 15% were obtained during the simulation of the PT power plant running for a year under each one of the four operational strategies considered. The results of these simulations make clear the need for further techno-economic optimization of the operational strategies defined, since revenues, costs and other operational factors depend not only on the amount of gas used, but also on when this gas is burned. (C) 2011 Elsevier Ltd. All rights reserved.