Concentrated Solar Power CSP plants are increasingly being considered for construction worldwide, in order to meet the demand for renewable power generation. The most promising technology considered today employs a central receiver, illuminated by a heliostat eld, using molten salts as working uid. A distinctive feature of these plant is the possibility of thermal energy storage, providing 15 or more hours of full power operation without solar irradiation. The state-of-the-art SAM software is often use for sizing the plant and evaluating the return on investment, assuming a straightforward and short-sighted control strategy. In this paper, a model similar to that used by SAM is developed and then used to demonstrate the potential advantages of optimal control, in a context of variable taris with higher prices during peak hours. The modelling and optimization problems are formulated with the high-level Modelica and Optimica languages, which allows to solve the problem with minimal eort. This paper is a rst step to promote the use of optimal control techniques and high-level modelling languages for the correct evaluation of the potential performance of CSP plants with thermal storage during their design phase.@en