Concentrated solar energy associated with thermal storage is gaining consideration among renewable energy sources since it provides efficient and low-cost solutions along with dispatchability. However, solar energy is intrinsically variable. In this context, a multi-domain numerical simulator can be a valuable aid to tackle the operation and control problems. In the present paper, we build a dynamic model of a concentrated solar power plant prototype using oil as the heat carrier fluid and combining a Fresnel solar field, an Organic Rankine Cycle and a dual media thermocline for thermal energy storage. The simulator takes the form of a large-scale Modelica model including both the physical and the control problems. The model is described component by component and the numerical results are compared to experimental data. Critical operational cases are studied to highlight both the model's capabilities and limitations: startup procedure, storage management and outlet temperature control.