Renewable Energy Variability in the Italian Peninsula: A Weather Regime Perspective

From the perspective of the energy transition in Europe, the Fit for 55 package outlines a comprehensive set of measures aimed at achieving climate neutrality by 2050 and reducing net greenhouse gas (GHG) emissions by 55% by 2030 relative to 1990 levels. In line with these objectives, the latest Italian Integrated National Energy and Climate Plan foresees a rapid expansion of renewable energy by 2030, with solar capacity rising from 37 GW in 2024 to 80 GW, and wind capacity growing from 13 GW to 28 GW.

As renewable generation expands and electricity demand rises due to increasing electrification, the power system becomes progressively more sensitive to meteorological conditions. This growing dependence highlights the need to better understand how the variability of solar and wind resources affects renewable power production throughout the year, as well as whether this variability has changed over recent decades.

In this context, weather regimes provide a valuable framework for energy system analysis, as they describe large-scale, physically consistent, and persistent atmospheric patterns that are inherently more predictable than local grid-point variables. Several studies suggest that weather-regime-based methods are more effective at predicting medium to long-term weather patterns, making them particularly useful for planning energy systems over the subseasonal-to-seasonal timescale.

Against this background, this study aims to characterize the variability of renewable energy production over the Italian peninsula as a function of weather regimes. In fact, while this approach has been widely applied in northern and central Europe—especially to investigate winter energy droughts (Dunkelflauten)—its application to Italy remains limited.

The methodology involves the estimation of solar and wind capacity factors using dedicated datasets. For solar energy, surface solar radiation from the Surface Solar Radiation Data Set – Heliosat, version 3 is combined with near-surface temperature data from the MEteorological Reanalysis Italian DAtaset - MERIDA to assess changes in solar production efficiency under increasing temperatures. Wind resources are characterized using the wind atlas Atlante EOLico ItaliANo - AEOLIAN, which provides wind speed data at multiple heights representative of wind turbine hub levels and has been specifically adapted for the Italian peninsula. Weather regimes are identified from ERA5 sea-level pressure fields using Principal Component Analysis.

The results show that distinct synoptic regimes are associated with markedly different renewable energy production patterns across Italy. For example, wintertime high-pressure regimes are generally linked to reduced energy production, although notable differences emerge depending on the specific high-pressure configuration and between northern and southern regions of the country.

Overall, these findings highlight the added value of a weather-regime perspective for interpreting and anticipating variability in renewable energy production in Italy, providing a robust basis for improving energy system management and resilience in a weather-dependent power system.