In the present paper, a model of a solar tower power plant (STPP) is presented. This is the result of a Master semester project led at the Laboratory for Industrial Energetic Systems (LENI) at the Swiss Federal Institute in Lausanne (EPFL). The modelized plant uses molten salt as heat transfer fluid (HTF), within a circuit including a direct storage system. The hot salt is used to provide power to a conventional Rankine cycle based on steam. For this first step a Rankine cycle without any improvement is modelled, in order to provide a simple running model being subject to improvements later. The model is realized using the program Vali, allowing to submit it to a multicriteria optimization algorithm, aiming the best feasible solution seen from a thermo-economic point of view. This report is exposing the work done on the model. The modelling of certain details is carefully described, then the operating parameters used for the model validation are presented. The results are then exposed in details, including several different strategies for the usage of the stored mass. A discussion of the presented results is then led, the results being compared to those of an unknown solar power plant (Solar Two). Finally, the major points that are subject to improvements are listed and the further work to be done is detailed.