Evaluating the Skill of Seasonal Wind Energy Forecasts in Germany

Seasonal renewable wind energy forecasts predict energy production, typically up to six months, with possible applications in supporting energy trading and optimizing operations and reducing grid risks. This study specifically develops the first seasonal energy forecasts tailored for Germany by applying a wind power model to seasonal wind speed forecasts from the German Climate Forecast System Version 2.1 (GCFS2.1). The hindcasts for years 1990-2000, with reanalysis data from ERA5 used as a baseline, are used for skill evaluation. The verification with three complementary metrics, probabilistic and deterministic, reveal that, despite the overall low skill and limited statistical significance, there might exist a few ‘opportunity windows‘ where the seasonal forecasts could be used as an additional input in a decision-making process. Concretely, mid-summer (June-August) and early winter (November-January) seasons in south Germany show a slight better performance, which may be connected to the predictability of large-scale circulations in these regions and seasons. The analysis also highlights the need for further calibration techniques that might enhance the forecast skills.