Optimal Operations of PV-ESS Considering its Capacity Credit

As renewable energy expands, accurately evaluating Capacity Credit (CC) has become essential for robust power supply and demand planning. This study assesses the CC of combined Photovoltaic (PV) and Energy Storage Systems (ESS) by applying the Effective Load Carrying Capability (ELCC) framework. To overcome the complexity of direct CC maximization, we propose two optimization models designed to improve CC through distinct objective functions: the ESS Charging/Discharging (ECD) model, which maximizes sales revenue, and the Weighted Peak Minimization (WPM) model, which mitigates grid risks by minimizing daily peak loads. Simulations conducted using Korean power load and generation data from 2019 to 2023 demonstrate that both proposed models achieve significantly higher CC compared to non-ESS or fixed-schedule operations. Specifically, while the ECD model yields the highest numerical CC, the WPM model provides a more stable and robust discharging profile by directly reducing peak demands regardless of price volatility. These findings underscore that efficient PV-ESS operation significantly enhances grid reliability and supply capacity. This research contributes practical operational strategies that can be integrated into future national energy frameworks to ensure power system adequacy.