Optimization of coal sustainability via hybrid renewable integration: A PVsyst-HOMER Synergistic framework for sustainable energy transitions

The growing urgency to decarbonize power systems while maintaining grid reliability has made hybrid energy systems an increasingly attractive solution, especially for coal-dependent regions. This study presents a novel hybrid energy optimization framework that integrates photovoltaic (PV), hydropower, and coal-based generation to enable a cost-effective and reliable power supply while facilitating a gradual transition toward low-carbon energy systems. Unlike conventional models that aim for immediate fossil fuel phase-out, this study proposes a pragmatic bridge model that utilizes existing coal infrastructure as dispatchable backup, enhancing grid stability without compromising sustainability goals. The methodology involves technical and economic modelling using HOMER Pro for hybrid system optimization and PVsyst for accurate PV performance analysis. Multiple constraints, including net present cost (NPC), cost of electricity (COE), reserve margin (≥15 %), CO₂ emissions threshold (≤30 % above baseline), and annual unmet load (≤0.5 %) are considered. A detailed sensitivity analysis was conducted to evaluate system robustness under varying solar irradiance and demand conditions. Results show that the optimized hybrid system (120 MW PV, 111 MW coal, 151 MW hydro) achieves the lowest COE ($0.0547/kWh) and CO₂ emissions (83,115,000 kg/year) with minimal unmet load (0.03 %). Environmental aspects are considered through explicit modelling of CO₂, SO₂, and NO_x emissions, as well as scenario-based carbon taxation. A high system performance ratio of 81.3 % and a capacity factor of 68.8 %, confirming the system’s technical and economic viability. The findings underscore the importance of flexible, region-specific energy strategies and provide a replicable methodology for investors, utilities, and governments seeking to balance energy security, environmental impact, and economic growth on the path toward carbon–neutral power systems. This research offers a versatile and globally applicable approach that can guide researchers in developing hybrid systems tailored to different geographic, climatic, and economic contexts, supporting worldwide efforts in sustainable energy transitions.