To save excess power large scale energy storage is required to overcome the short term storage. The increasing demand of electricity and neglecting the excess energy presented the idea of Power to Gas (P2G), because gases can be stored economically for long time, while electricity cannot be stored economically for long time. P2G plays a vital role in enhancing large-scale integrated energy system in energy sector. The process of converting surplus electrical energy into gases and its planning in an integrated energy system for different purposes is significant for developing the technology. This paper reviewed the study of integrated energy system with the power to gas technology. The conversion technologies, basics, storage capacity and siting in integrated energy systems are analyzed for modeling which assesses to their suitability for applications. Coupling, aims, applications and economic analysis to enhance the performance of the system, balance the system and to offer better facilities to consumers are investigated. The large capacity of P2G system, can provide long term energy storage requirements. P2G need further research work to address the issues of cost minimization as it is very expensive technology, optimal location, economy, energy efficiency improvement and proper methodologies for integration.