A retrofitted PVT collector assembled and installed together with a conventional PV panel, on northern hemisphere, facing south-west and tilted to 40 degrees. In order to evaluate the system's performance during the autumn to winter period, outdoor experiments were conducted and a PC-based automatic data acquisition unit has been used. The results show that the PVT collector managed to slightly increase its average electrical energy yield by 0.32% during the experimentation period and obtained additional thermal energy with daily average efficiency of 20.33%. Moreover, PVT's moderate thermal insulation revealed a detrimental factor regarding its thermal energy generation. Furthermore, a steady state model was created based on Hotel-Wilier equation modified for PVT collectors by Florschuetz. Two typical days were chosen and simulated for the model's evaluation. The simulation outcomes revealed good agreement between the model and the measurements, with average figures of 3.12% for useful heat and for electricity between -4.46% and 10.72%. Finally, the PVT's model, managed to predict the system's operation on an average day's values with -8.25% and 7.49% for useful thermal energy and electrical energy respectively, while the corresponding monthly figures of standard deviation were 2.23% for useful heat energ,y and 5.71% for electricity. (C) 2017 Elsevier Ltd. All rights reserved.