Techno-Economic and System-Level Evaluation of PV-Integrated Energy Storage Systems for High Renewable Penetration Grids

Abstract

Energy Storage Systems (ESS) are increasingly recognized as critical enablers of grid flexibility in power systems with high renewable energy penetration. This study presents a comprehensive techno-economic and system-level evaluation of a photovoltaic (PV)-integrated ESS operating under grid-connected and emergency modes. Unlike prior studies that focus primarily on conceptual or policy perspectives, this work integrates operational modeling, economic feasibility analysis, and national-level storage sizing considerations within a unified framework. At the project level, a 5 MW / 20 MWh commercial-scale ESS operating under time-of-use (TOU) pricing was evaluated. An arbitrage-only operation yielded an internal rate of return (IRR) of 7–9% and a payback period of approximately 10–11 years, indicating marginal yet feasible profitability under current tariff spreads. When multi-service revenue stacking—incorporating frequency regulation, reserve provision, and peak shaving—was applied, IRR improved to 11–14%, and the payback period decreased to 7–8 years. Sensitivity analysis confirmed that a 30% reduction in battery capital costs is the dominant factor affecting economic viability, with an IRR above 15%. Operationally, annual simulations of the PV–ESS system demonstrated a round-trip efficiency of approximately 87%, a 20% reduction in peak demand, and emergency autonomy exceeding the required 2-hour duration.