Photovoltaic power forecasting methods and applications to support high solar penetration = Metodi di previsione della generazione fotovoltaica e loro applicazioni a supporto di un’elevata penetrazione solare

In this work we investigate multiple aspects of photovoltaic power forecasting technology: (1) Global Horizontal Irradiance forecast; (2) site/non-probabilistic PV power forecast; (3) regional PV generation forecast; (4) multimodels approach, (5) probabilistic power forecast. For each topic, we develop original forecast models/methods analysing their accuracy using Italy as a case study. We then study the technical-economic advantages for producers/traders, distributors and transmission operators resulting from the use of accurate solar forecasts. We show how these forecasts can be effectively and profitably used to reduce supply/demand imbalances and reserve margins and their related costs in the balancing energy markets at current and future PV penetration levels. We go beyond photovoltaic power forecasts, proposing the use of a new concept of photovoltaic systems that we call: "flexible" photovoltaic plants to first provide auxiliary unbalance services and then firm, full dispatchable solar generation 24/365 at lower energy costs than current. Finally, we show how it is possible to implement in Italy a least-cost 100% renewable energy transition driven by a progressive penetration of “flexible” PV systems.