An optimal energy management strategy is difficult for an efficient operation of hybrid renewable energy systems due to the instability of energy resources. The present study analyzes a hybrid PV-battery integrated with the pump-hydro-storage system (PHSS) utilizing the rainfall potential at various probabilities of power supply loss (PPSL). Two configurations have been studied. Configuration-1 is a PV-battery system, and Configuration-2 is a hybrid PV-battery-PHSS. PPSL are varied between 0.00 and 0.10 in steps of 0.02. The particle swarm optimization technique is used for size optimization based on the Levelized Cost of energy minimization. Configuration-1 and Configuration-2 at PPSL of 0.00 are highly oversized. Configuration-2, compared to Configuration-1, has less excess power due to the integration of PHSS. A decrease in the power supply reliability by just 2 has caused the decrease in the Levelized Cost of energy by about 31.3 for Configuration-1 and 28.8 for Configuration-2. The power system efficiency for Configuration-1 at PPSL of 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10 is 34, 71, 77, 79, 80, and 80, respectively. However, for the Configuration-2, the power system efficiency compared to Configuration-1 at PPSL of 0.02, 0.04, 0.06, 0.08, and 0.10 has increased by about 11.8, 2.8, 0.0, 1.3, 1.3, and 1.3, respectively. © 2022 International Solar Energy Society