The present work is focused on the development of a simulation model for an existing cogeneration power plant, which utilizes a solar thermal field with parabolic trough solar collectors coupled to an Organic Rankine Cycle engine. The power plant is modeled in the trnsys v.17 software package and its performance has been validated with real operating conditions. The simulated system (concentrated solar power (CSP) field and ORC engine) is the main part of a hybrid power plant located near “Ziloti” village of the Municipality of Xanthi, in northeastern Greece. The construction of the hybrid power plant was funded by the Strategic Co-Funded Project of the European Territorial Cooperation Program Greece–Bulgaria 2007–2013 with the acronym ENERGEIA. The power plant simulated in this paper includes a 234 kWth solar parabolic trough collector (PTC) field, a 5 m3 thermal energy storage tank, and a 5 kWe ORC engine for the production of thermal and electrical energies. The results of the simulations present small deviation in contrast to the real operating data of the CSP power plant coupled with the ORC engine, therefore the simulation model is considered as reliable.