The escalating energy demand in today’s world underscores the need for a consistent and continuous power supply. There is a push towards promoting renewable energy sources to address this demand because of their positive impact on the environment and their widespread accessibility. Particularly in Rwanda, for the radial distribution network, the reliability improvement in electricity supply requires rectifications of power system infrastructure, including transmission, distribution system, and an increase in energy generation capacity. To evaluate the influence of renewable energy sources (RES) on the reliability of Rwanda’s power grid, Solar Photovoltaic (PV) systems combined with Battery Energy Storage Systems (BESS) are introduced into the Gatumba and Ntongwe feeders. For reliability enhancement of the grid to the feeders where solar PV system and BESS are connected, protection switches are configured so that the PV systems and BESS supply the load demand in the absence of the grid, thereby increasing the generation capacity and reducing interruption frequency and duration. Simulation results from DigSILENT and PV*SOL simulation tools showed that by integrating solar PV systems with BESS to Gatumba and Ntongwe feeders, the system reliability ameliorates by 71.6% and 95.5% for system average interruption frequency and duration, respectively.