Economic Assessment of Self-Consumption PV-Based On-Site PPA with ESS Integration

This study evaluates the economic feasibility of integrating an energy storage system (ESS) into a self-consumption photovoltaic (PV)-based on-site power purchase agreement (PPA) model for RE100 consumers. To this end, the optimal ESS capacity was derived under a 1:1 PPA structure, using actual electricity rate structures, contract demand, and historical electricity consumption data from a real consumer. A case study was conducted for an RE100 consumer with an annual electricity consumption of approximately 383 GWh. The results showed that economic can be achieved even with a fixed contract price of 200 KRW/kWh, based on the 2025 energy charge structure. In addition, the integration of ESS was found to be economically infeasible due to high initial investment and O&M costs. However, participation in multiple demand response programs showed that economic feasibility can be achieved, with a maximum net profit of 9.8 billion KRW and a benefit–cost ratio of 1,812, over the life of the battery.