Techno-economic optimization of a hybrid microgrid with integrated backup storage and vehicle-to-grid functionality

This study presents the techno-economic optimization of a hybrid backup system integrated within an off-grid microgrid framework with electric vehicle (EV) grid-interaction capability. A real-world case study from a remote region in Egypt is used to evaluate system performance under realistic operating conditions. The optimization problem is formulated to minimize the net present cost (NPC) while ensuring system reliability using a penalty-based loss of power supply probability (LPSP). The system integrates photovoltaic (PV), wind turbines (WT), battery energy storage systems (BESS), hydrogen energy storage systems (HESS), and EVs. The novelty of this work lies in the development of a coordinated multi-storage energy management strategy that integrates BESS, HESS, and constrained EV participation within a unified optimization framework. The results show that the BESS-only configuration achieves the lowest cost (NPC ≈ $20.33 billion), while the PV/WT/BESS/HESS configuration results in the highest cost (NPC ≈ $25.48 billion). The proposed PV/WT/BESS/HESS/EV configuration provides a balanced solution with an NPC of approximately $22.79 billion while maintaining near-zero LPSP. EV integration enhances system flexibility, reducing the required BESS capacity by 44.8% relative to the HESS-only configuration, while also lowering reliance on hydrogen-based long-term storage, thereby mitigating the high capital costs associated with extended-duration storage components. These findings demonstrate that coordinated multi-storage management significantly improves the techno-economic viability and operational resilience of large-scale off-grid microgrids in remote regions.