One of the main directions of global research areas in the energy sector is the possible option for the storage of energy in large quantities. This is due to the necessity to handle intermittent electricity generated by renewable energy sources. Large-scale energy storage is increasingly important in the development of the energy sector in the context of diversification of energy sources and providing energy security. One of the promising storage technologies is power to SNG (PtSNG), which uses hydrogen which is converted into synthetic natural gas (SNG) as the energy carrier. This paper presents an energy analysis of an integrated PtSNG system based on a solid oxide electrolyzer (SOE). Surplus electricity from renewable energy sources is used to split hydrogen and oxygen in the electrolysis. The great advantage of solid oxide electrolysis over conventional low-temperature electrolyzers is the outstanding efficiency, in excess of 85%. The methanation process converts hydrogen from SOE and carbon dioxide into SNG with a high methane content (~90 vol.% dry basis), that can be injected into the gas grid and used in the existing natural gas infrastructure. The simulation model of the analyzed system, which combines electrolysis and methanation processes, was developed in Aspen Plus. According to the sensitivity analysis performed, CH4 content in the SNG increases from the range of 0.67 - 0.77 for the atmospheric pressure of the methanation process, to the range of 0.81 - 0.87 for the overpressure of 5 bar. For the adopted stream of reactants (hydrogen and carbon dioxide) for the methanation process (5.5 Ndm3/min, H2:CO2 = 4:1), it was estimated that the minimum power of SOE installation should be equal to 0.828 kW to produce and deliver the required amount of hydrogen needed for the production of SNG. The results of the estimated efficiency of the considered power to SNG system are in the range of 66.51-76.34%.