Small, distributed energy storage (ES) devices could be used to increase self-consumption of generated energy inside building-integrated microgrids, helping to flatten the load curve of the electrical power system (EPS). ES are especially desired in systems where rising penetration of intermittent renewable energy sources (RES) with its variable nature has become a challenge for distribution grid operators to maintain voltage quality inside the permissible range. Increasingly, it requires the involvement of new distributed resources, such as energy storage devices to smooth power fluctuations of RES and to avoid long-term voltage rises. To achieve the best results such devices should be located as close to the micro source as possible — very often in residential areas. This in turn requires meeting many restrictions such as limited space, high level of safety and low energy storage costs. This paper discusses the properties of small Zinc Bromine (ZnBr) flow batteries ascertained in experimental research. The simple equivalent model of the ZnBr battery has also been developed and described.