Among the energy storage technologies, installations that use hydrogen as an energy carrier, such as Power-to-Gas (PtG) systems are becoming more and more popular. This paper presents an analysis of the power-to-gas installation as an exemplary solution of excess electricity from renewable energy sources storage system. The installation contains an integrated module of the electrolysis process, used for hydrogen production, and a system for synthetic natural gas (SNG) production. An analysis of electrolyzers and methanation units as parts of energy storage installation is performed. Advantages and disadvantages of all systems selected for analysis in the article are presented. The simulation model of analyzed power-to-gas installation, built in the Aspen Plus program, was used for calculations. A thermodynamic analysis of various variants of an energy storage installation and the potential of the use of waste heat is shown. Calculations were made to determine the efficiency of the installation. Calculated values of power-to-SNG efficiency of the analyzed cases remain at the level of 0.49-0.51.