The energy strategies of many countries are aimed at decarbonizing, decentralizing, and digitalizing the energy sector. In addition, the active growth of renewable energy installed power requires the implementation of additional highly maneuverable capacities to balance power systems and use them more efficiently. Such opportunities can be provided by energy storage systems that can be used in the domestic sector, industry, and large-scale storage systems, such as power systems. This paper aims to develop a methodology for determining the optimal operating modes of energy storage systems for an industrial enterprise, which is based on the analysis of hourly electricity tariffs in the day-ahead market to reduce the cost of paying for electricity. Using the proposed approach allows to reduce the company's daily expenses for electricity by 5,4%.