The paper discusses the principles of building uninterruptible power supply systems for backup energy provision for remote or stand-alone energy consumers with inclusion of renewable energy sources. There is a problem for many energy system operators to provide energy connections for outlying clients, like stand-alone farms. These connections cost too much and are a burden both to the energy system operators and clients. In order to decrease these grid connection costs by introducing additional renewable resources a new type of inexpensive energy flow management and energy storage system was developed, which would optimize grid transmission energy flows for consumers, who occasionally need high power levels for short time periods. This paper describes the characteristics of inverters with direct connection to the power grid, the criteria for the efficiency of the uninterruptible power supply power system. Based on the analysis of the features of the operation of the main types of uninterruptible power supply units, the principle of building an efficient uninterruptible power supply system based on a converter with direct connection to the electrical grid controlled by a digital system with tracking of the maximum power consumption point is justified. The technical characteristics of the power system were determined and evaluated, the conceptual diagrams of the control device of the energy system of uninterrupted power supply and the algorithms of its operation were developed. The proposed solutions are tested experimentally by the technical implementation of the developed schemes.