This paper describes the general problems of the integration of renewable energy sources into the power system, with an emphasis on the distribution network, both its planning and the influence of distributed sources on its operation. The paper describes the methods of determining the optimal power and connection point of the distributed source in the distribution network based on the sensitivity factors of the change in losses in the network, the method of the golden ratio, the method based on the assessment of the change in power losses in the network based on incidence matrices. The described methods were implemented in the form of a software package and were tested on radial distribution networks. The paper presents the obtained results, which include the optimal locations and power of distributed sources, and provides a comparison of the obtained results for the different methods described in the paper.