Risk-based validation of renewable energy forecasting: a test case for Italy
摘要
We propose a forecasting and validation framework for log-changes in solar and wind power generation, with a focus on large forecast deviations relevant for power system balancing. Forecast accuracy is evaluated using standard point-error metrics, while extreme deviations are assessed through a Value-at-Risk (VaR)-based analysis of absolute forecast errors. In this setting, VaR is employed as a reliability-oriented validation measure: the unconditional frequency of threshold violations assesses calibration at extreme quantiles, while their temporal occurrence may reflect persistence in renewable generation shocks that can require operational actions such as curtailment or reserve activation. Using Terna’s 2023 data, we compare a physics-informed stochastic model with benchmark approaches including ARIMA-GARCH, SARIMA, Vasicek, Naive, LSTM, Random Forest and XGBoost models. Results show that the proposed model delivers the strongest point-forecast performance among the considered specifications and maintains comparable calibration at operational quantile levels. Clustering of threshold violations is observed across all models and is consistent with persistence in renewable generation regimes.