Design and Optimization of Off-Grid Hybrid Renewable Energy System for Nüzhetiye Village, Gölcük, Kocaeli: Techno-Economic Analysis Using HOMER Pro

This study investigates the techno-economic feasibility of an off-grid hybrid renewable energy system designed to meet the energy demand of an approximately 100-household rural settlement in Nüzhetiye (Gölcük, Kocaeli, Türkiye). System sizing and optimization were conducted using HOMER Pro, and two approaches were evaluated: a hybrid configuration where electrical and thermal loads are considered together, and a full-electrification approach in which the thermal demand is modeled as an electrical load.The results indicate that combining PV and wind generation with biogas-based backup and battery storage improves supply reliability under off-grid conditions. From an economic perspective, the levelized cost of energy (LCOE) is approximately 0.24 $/kWh for the hybrid scenario, while it decreases to about 0.21 $/kWh under the full-electrification scenario, suggesting a lower unit energy cost potential for electrification. In terms of sustainability, the renewable energy contribution is around 74% in the hybrid scenario, whereas the full-electrification scenario can achieve 100% renewable supply under suitable design conditions. Overall, the study demonstrates that off-grid energy supply for rural communities is achievable when local renewable resources and biogas potential are jointly utilized, and it provides a practical reference for similar microgrid applications.