Distribution systems reliability is a great concern to any electric power utility company. Power utility companies are working to provide reliable power through many systems.In this thesis, the reliability of an electric power distribution feeder R5-G2 is evaluated. Based on the two years period (2020 and 2021 ) recorded data collected from EEU SCADA center, R5-G2 have large interruption data and longer distance from the supply point. System reliability indices were calculated using both mathematical and simulation methods. The System Average Interruption Frequency Index (SAIFI) and System Average Interruption Duration Index (SAIDI) are 149interruption per customer per year and 246hours per customer per year respectively. Due to this, the system is not reliable by the standard of Ethiopian Electric Agency (EEA).This gap calls for searching of effective methods for mitigating the interruption of the distribution network. Among different solutions to minimize power system interruption, integrating Distributed Generation technology to the current network as backup isevaluated in this thesis. Distributed generation is a generation of an electric power close to the load. The resources of DG are photovoltaic (PV), fuel cells, wind generators, micro turbines and so on. In this thesis, based on availability of the resource, cost factors, and utilization area, photovoltaic (PV) system is selected from other distributed generation resources. In this thesis, four case studies has been investigated at four load points to get improved value of reliabilityindices and the best location of distributed generation.The size of the DG is selected based on the peak load of the feeder. The DG fed to the grid as backup when there is power interruption. A simulation study for reliability analysis is carried out using DIgSILENT software. When integrating DG at the end of the feeder the simulation value of SAIFI and SAIDI is 24.97 interruption per customer per year and 54.95 Hour per customer per year respectively.With the presence of DG, the simulation result shows that the reliability indices SAIFI and SAIDI is reducedby 83.0467% and 78.469% respectively.As shown from the result, the integration of DG with R5-G2 improves the reliability of the distribution system effectively.