The use of compressed air energy storage (CAES) systems instead of conventional energy storage systems in large scale grid connected photovoltaic (PV) plants has already been proposed and investigated thermo-economically, resulting to very satisfactory outcomes. On the other hand, CGS (city gate stations), in which high pressure natural gas is expanded to much lower presser levels, has been proved to be a very suitable place for producing free electricity by employing turbo-expanders instead of conventional throttling valves. In this work, the feasibility of employing a CGS power output for improving the performance of a grid connected PV plant accompanied with a CAES system and enhancing its power output stability is studied. Comprehensive energy analysis and economic assessment on the proposed configuration is carried out and the results are discussed thoroughly. Finally, the performance of this hybrid configuration is compared with the PV plant and the CGS station while working individually. IRR (Internal rate of return) method as an authentic economic evaluation approach is used for comparing the considered systems economically. (C) 2016 Elsevier Ltd. All rights reserved.