Optical and thermal analysis of the most well-known solar concentrator system; parabolic trough collector (PTC) are investigated and analyzed. To evaluate performance of the PTC, four cities of Iran with different weather conditions are chosen as case studies. Effective parameters such as concentration ratio, incident angle correction factor, collector mass flow rate are considered. The main objective of this work is evaluation of the solar energy potential using PTC in under consideration cities with different climates. Numerical modeling of the analysis is done using MATLAB software. Simulation results shows that Shiraz, with an average annual thermal efficiency of 13.91% and annual useful energy of 2213 kWh/m2, is the best region to use solar concentrator systems. The impacts of other parameters such as fluid inlet temperature, input fluid flow rate and aperture area of the collector on the output of the system are also investigated. Finally, the effect of using nanofluids as heat transfer fluid on increasing the heat transfer is investigated. © 2017 Elsevier Ltd