Baseline Efficiency: a new Key Performance Indicator for PV Systems

This work introduces Baseline Efficiency (BE), a novel key performance indicator (KPI) for photovoltaic (PV) systems. BE quantifies system degradation and serves as a reference to identify thermal losses, faults, and other performance deviations. Calculated through PV output modeling, instantaneous efficiency calculations, filtering, and daily aggregation, BE captures changes in maximum power point (MPP) current, voltage, and power, and can incorporate openand short-circuit data to reflect changes across the entire IV curve. By integrating BE, long-term PV output estimations become more accurate compared to static models, which degrade in precision due to system aging. BE also enhances fault detection and power forecasting when paired with weather forecasts. Results from a 6-year dataset demonstrate that BE stabilizes estimation accuracy for power and current, with voltage showing minimal degradation.