Abstract: With the introduction of the "double carbon" goal, the future distribution network will face a very high proportion of new energy such as photovoltaic. The increasing penetration of distributed photovoltaics in the distribution network leads to frequent issues such as voltage violations and reverse power flow. This paper proposes an optimization configuration method for distributed energy storage based on moment difference analysis, which is built upon the existing voltage regulation methods and reactive power compensation in distribution networks. The method is proposed to address situations where the on-site accommodation of distributed photovoltaic capacity is not feasible due to its large size, and the high-power return of photovoltaics causes node voltage to exceed limits. The paper introduces the concept of "photovoltaic moment" and "load moment", and subsequently presents the concept of "moment difference". It derives formulas and provides theoretical analysis of the relationship between "moment difference" and node voltage. The paper details the methods for calculating the photovoltaic moment and load moment. Based on this, a new method of energy storage optimization configuration of distribution network based on moment difference analysis is proposed. The goal is to ensure that no node in the distribution network exceeds the upper voltage limit when photovoltaic power is returned. An example of IEEE 33 node distribution system shows that compared with traditional intelligent optimization algorithms, the proposed method can directly determine the installation location of energy storage, which has high computational efficiency, accurate calculation results and strong engineering practicability.