In this study, a photovoltaic-thermal (PV/T) combi collector was assessed theoretically and experimentally in weather conditions of Sanandaj city in summer, August, 2016 in simple, water, and air modes under unstable conditions from 8:00 a.m. to 18:00 p.m. The air mode with 0.01 kg/s mass flow rate and the water mode with 0.003 kg/s mass flow rate were investigated. The maximum overall efficiencies of the air and water modes were 0.47 and 0.69, respectively, and mean electric power rates generated in the simple, air and water modes were 64.5, 66.7 and 68.2 W, respectively. The energy and exergy means obtained for PV collector during the experiment were found to be 125 and 119 W/m(2), respectively. Then, RMSPD, RMSE and MAPE analyses were performed for simulation, showing the accuracy of the model. Finally, the linear correlation coefficients for the parameters "PV collector temperature with solar radiation intensity" and "PV collector temperature with outlet air temperature" were 0.991 and 0.998, respectively, indicating a strong linear correlation between these parameters. (C) 2017 Elsevier Ltd. All rights reserved.