In-depth analysis of next-generation hybrid PV–SOFC power system for nearly-zero energy building using an advanced thermodynamic and multi-objective optimization approach

This study develops and optimizes a hybrid energy system integrating solid oxide fuel cells (SOFC), photovoltaic (PV) panels, battery storage, and waste heat recovery via a single-effect absorption chiller and thermal energy storage for an educational building in Najran, Saudi Arabia. A comprehensive thermodynamic analysis comparing dry and steam reforming pathways was conducted under hot-arid climatic conditions. A multi-objective optimization framework based on NSGA-II was implemented to maximize system efficiency, minimize operational costs, and reduce CO2 emissions, with TOPSIS applied to select compromise solutions from the Pareto front. The comparative analysis revealed that dry reforming produces exhaust temperatures 40–65 °C higher than steam reforming, enhancing waste heat recovery despite 5.15 percentage points lower stack efficiency. The highest net electric power of 1288 kW was achieved at 7214 A/m2 current density, with an optimal inlet temperature of 596 °C yielding 1214 kW. The dry reforming TOPSIS solution achieved 52.3% system efficiency, $87,400/year cost, and 148 tonnes CO2/year, outperforming the steam reforming TOPSIS point of 50.8% efficiency, $91,200/year, and 155 tonnes CO2/year. Waste heat recovery integration improved exergy efficiency by 15% compared to standalone SOFC operation. Component-wise exergy destruction analysis identified the SOFC stack and afterburner as dominant irreversibility sources at 38% and 24%, respectively. Normalized sizing indicators including a PV-to-floor area ratio of 1.48 m2/m2 and battery-to-peak load ratio of 1.77 kWh/kW are proposed for preliminary design of similar systems in high-solar regions.