The object of this study is the process of integrating industrial energy storage units (IESU) into distribution electrical networks. Their connection helps reduce peak loads on the elements of networks and improve the quality of voltage. However, determining the optimal IESU capacities and their places of connection to networks is associated with objective difficulties. It is necessary to apply comprehensive optimality criteria and take into consideration active restrictions. In addition, the trends in the development of distribution networks and pricing in the energy market are partially undefined. The current study proposes the formalization of the problem of optimizing the placement of IESU in distribution networks and reports a new method to solve it. Its application contributes to a reasonable definition of the volume of investments in the development of IESU, taking into consideration technical restrictions on the part of distribution networks. To solve the problem of multifactorial optimization of the energy storage system, the decomposition and method of ideal current distribution (for electricity losses) were applied. It is shown that this problem can be reduced to an iterative calculation of current distribution in the substitution circuit of power grids with active resistances. And, to take into consideration economic factors, a technique to determine and adjust fictitious resistances was devised. An optimization algorithm has been proposed that ensures a decrease in the number of computing operations and an increase in the reliability of obtaining an optimal solution. Its application makes it possible to take into consideration the dynamics of pricing, consumption, and electricity generation processes over long periods. This contributes to the formation of sound design decisions on the connection of IESU to distribution networks