Abstract
Abstract This study presents the design and simulation of a hybrid solar PV-diesel refrigeration unit providing reliable cold storage in off-grid regions, using Itunta, Nigeria, as a case study. The methodology involved a detailed energy analysis for a 78.2 kWh/day load, followed by a stochastic performance simulation. Results indicate that the analytical baseline comprising a 17.0 kWp solar array, a 159.0 kWh battery bank, and a 15 kVA diesel generator consistently meets demand with a 95% renewable energy fraction (27,115 kWh/year). Performance analysis revealed an average Solar Performance Ratio (SPR) of 82.5%, with a seasonal peak of 142.4% in July, identifying critical deficit windows bridged by the backup generator. Advanced technical modeling utilizing an Arrhenius-based kinetic analysis revealed that the battery’s State of Health (SoH) reaches its 80% end-of-life threshold in approximately 9.2 years. Stochastic simulations confirmed high reliability, with a Loss of Load Probability (LOLP) below 0.5%. Furthermore, a dual-target “sweet-spot” optimization mathematically identified a global optimum of 30 kWp PV and 60 kWh storage, demonstrating that oversizing solar generation is more cost-effective than excessive battery capacity. This offers a technically superior path for future deployments. Economic assessments show that the hybrid system has a significantly lower Levelized Cost of Electricity ($0.18–$0.23/kWh) than diesel-only equivalents ($0.85–$1.15/kWh), achieving a simple payback period of 3.47 years. Ultimately, this research provides a mathematically validated and economically attractive blueprint for sustainable cold chain management in underserved communities.