This study presents a comprehensive techno-economic and environmental assessment of two rooftop solar photovoltaic (PV) retrofit options—119. 16 kW and 205. 2 kW—for a commercial-educational facility in Maryland, USA. Using detailed engineering proposals obtained from the EnergySage Solar Marketplace, the analysis evaluates investment cost, projected energy generation, incentive structures, and long-term financial performance over a 30-year lifetime. Key metrics include Net Present Value (NPV), Internal Rate of Return (IRR), Levelized Cost of Energy (LCOE), simple payback period, cumulative savings, and carbon emission reductions. A deterministic optimization model is then applied to determine the system size that maximizes economic and environmental value. Results show that both systems are economically feasible, achieving IRRs between 13. 7% and 13. 9% and payback periods of approximately 6. 6–6. 7 years. The 205. 2 kW system provides substantially higher lifetime savings (US1. 41 million) and carbon reductions (4, 270 tCO₂), whereas the 119. 16 kW configuration offers slightly superior capital efficiency. The optimization model identifies the 205. 2 kW system as the optimal long-term solution. These findings provide actionable insights for institutional facilities seeking cost-effective and sustainable rooftop PV deployment.
Huang Ting (Sat,) studied this question.