Comparative study on flat photovoltaic (PV) string and symmetric compound parabolic concentrator (CPC) photovoltaic system has been presented in this paper. Two flat PV strings and two unglazed PV-CPC systems are considered. The cells of each of the flat PV and PV-CPC strings are subjected to cooling to reduce temperature. The performance of the two configurations with and without cooling is evaluated numerically and experimentally. The numerical models for the flat PV string and the PV-CPC systems are solved using Engineering Equation Solver (EES) software and the concentration ratio of the CPC system is considered as 2.3X. Absorbed energy is calculated with and without cooling for the PV-CPC and flat PV systems. The absorbed energy is used to solve the energy balance equations on different nodes of the system from which the cell temperature was determined. The results showed that the maximum power output of the flat PV string with cooling was approximately 21 W which gives about 49% more than the power obtained without cooling. The maximum power output of the PV-CPC system with cooling was approximately 34W which is about twice of the power obtained in the absence of cooling. It was found that the power output of the PV-CPC system is higher than that of the flat PV string with and without cooling by 39% and 23% respectively. Comparison of the numerical results with experimental data showed good agreement for the two configurations. The maximum percentage differences between the numerical and experimental power output for the flat PV with and without cooling are 5% and 7%, respectively. While those of the PV-CPC system with and without cooling are 9% and 11%, respectively. (C) 2014 Elsevier Ltd. All rights reserved.