Off-grid microgrids powered by renewable energy face a critical design challenge: balancing system cost against supply reliability in regions where grid connection is impractical. A new study addresses this optimization problem for hybrid systems combining photovoltaic panels, wind turbines, and pumped hydro storage reservoirs, designed specifically for remote mountainous terrain with low air density.
The research compared six advanced optimization algorithms—particle swarm optimization (PSO), differential evolution (DE), grey wolf optimization (GWO), sine-cosine algorithm (SCA), whale optimization algorithm (WOA), and Moth-flame optimization (MFO)—to minimize the cost of energy while maintaining acceptable reliability. The primary metric was loss of power supply probability (LPSP), measuring the fraction of demand that cannot be met by available generation and storage.
Results show PSO identified the most economical and reliable designs. At zero permitted outages (0% LPSP), the optimal configuration yielded 875 PV units, 100 wind turbines, 60 kW inverter capacity, and a 7,657 cubic meter upper reservoir. This design delivered electricity at 0.2128 $/kWh with 100% supply certainty. At 5% allowed LPSP—a practical trade-off permitting brief outages—costs dropped to 0.2041 $/kWh with marginally smaller component sizes.
Differential evolution achieved similar solutions but required the shortest computation time, offering a practical alternative when speed matters. Statistical analysis using Shapiro–Wilk normality tests and non-parametric Mann–Whitney comparisons confirmed PSO's superior performance across repeated optimization runs.
Sensitivity analysis revealed that system sizing responds significantly to changes in load demand and resource availability. The fully renewable design eliminates diesel generator costs and emissions, while pumped hydro storage addresses the intermittency of wind and solar generation by storing excess energy in elevated reservoirs and releasing it during deficit periods.
These findings validate the technical and economic feasibility of scaling hybrid renewable microgrids to serve isolated communities where conventional grid infrastructure remains prohibitively expensive.
