Modelling and Simulation of Solar Generator Battery Hybrid Systems to Improve Energy Reliability

Abstract

Hybrid energy systems are essential for addressing unreliable power supply in off-grid healthcare facilities. In Nigeria, frequent grid outages force reliance on costly, polluting diesel generators, compromising healthcare delivery. This study simulated a solar-generator-battery hybrid system to improve energy reliability for medical facilities. The study employed MATLAB/Simulink to model a system integrating solar PV, lithium-ion batteries, and a diesel generator. Component sizing was based on load assessments (kWh/day) and solar irradiance data (kWh/m²/day). The four different scenarios tested in the study were baseline operation, low irradiance, increased demand, and prolonged outages. Four test scenarios showed the honesty of the hybrid system and its versatility. In base scenarios, the system had 95% availability, and the solar PV replaced 72% of the required energy resources, whereas the runtime of the generator was equal to only 2.3 hours per day. Under the low solar irradiance periods, solar contribution was reduced to 38%, which led to an increase in generator run time to 5.1 hours/day. However, the system was exposed to an additional 20% increase in the energy demand; it was steady, and the generator hours slightly increased to 4.7 hours per day. During the low irradiance condition simulated in the seven consecutive days with poor sunlight, the generator gave 68% of the total energy, and the state of charge near the bottom limit was reached on the third day. The hybrid system ensured continuous power, reduced diesel dependence by up to 60%, and offered resilient support for essential healthcare services in developing regions.