There are many applications for electric storage systems (ESS) in manufacturing systems. While applications for maintaining production in case of a blackout are already established and economical, applications for optimizing energy supply are becoming increasingly interesting for manufacturing companies. Atypical grid usage is one application for optimizing the energy supply which has the potential to reduce the grid fee of industrial consumers. The grid fee for industrial consumers depends on the characteristics of the energy consumption. The smoother the power is drawn from the grid, the less grid fee has to be paid. This goal can be achieved by integrating an electric storage system. Electric storage systems offer high power and capacity, making them the ideal solution for this application. The challenge is the sizing of the electric storage system and the resulting economic efficiency. In this article a sizing methodology for electric storage systems, aiming for atypical grid usage, is presented.