Ireland's all-island power system carries around 6.8 GW of wind capacity across more than 3,800 turbines, and regularly runs at one of the highest instantaneous wind shares of any synchronous grid in the world. OpenWindCast publishes an independent day-ahead forecast for the island and scores it daily against the forecast EirGrid and SONI publish.
Averages across all zones. Every number on this page is recomputed daily from the public record below.
Great Britain has one of the largest onshore wind fleets in Europe, with most capacity in Scotland. The forecast covers GB onshore wind and is scored against NESO's own forecast, published through Elexon.
Every forecast ships with an 80% interval. This shows how often the actual output landed inside it, and how wide it was.
Irish wind sits along the Atlantic seaboard, from Kerry and Clare north through Mayo, Sligo and Donegal, with further capacity in the Northern Ireland uplands. It is the most exposed fleet in the portfolio. Atlantic depressions reach Ireland with no land upwind to modify them, so the timing of a front is decided far out over the ocean, and a few hours of error in that timing is worth a very large swing in output. Forecast error as a share of capacity is correspondingly higher here than in more sheltered parts of Europe, which reflects the meteorology rather than the operator.
The benchmark is EirGrid and SONI's own all-island day-ahead wind forecast, published through the ENTSO-E Transparency Platform. Installed capacity is maintained separately, from EirGrid and SONI's renewable constraint and curtailment reporting, because the all-island system does not publish it in the usual ENTSO-E series.
One value per day: onshore wind output at 11:00 local time tomorrow, expressed as a load factor and published before 12:00 local, ahead of the day-ahead auction rather than after it. Once EirGrid's own forecast for that day is published it is captured and held fixed, and once the metered output is settled both forecasts are scored against it. Every day is added to the record below and nothing is removed or rewritten later, so the full history is there to be checked rather than summarised. How this is measured.
Because the Single Electricity Market covers the whole island, and EirGrid and SONI forecast and settle it as one system. Splitting it would not match anything the market trades.
Irish offshore capacity is very small next to 6.8 GW of onshore and is not separated out.
Compare every zone: how accurate are European TSO wind forecasts?
Mean absolute error as a percentage of installed capacity. Lower is better.
The share of days the forecast lands closer to the metered output than the operator's own forecast.
The range the actual output should land in 80% of the time, recalibrated daily.
NESO's published day-ahead 11:00 forecast, a fixed yardstick that is never used as an input.
A forecast of wind generation for the next delivery day, issued before the day-ahead electricity auction closes at 12:00 CET. Market participants use it to decide how much wind energy to bid into the auction.
One value per zone per day: the onshore wind output at 11:00 local time on the next day, expressed as a load factor and converted to megawatts with the installed capacity the grid operator publishes. Every forecast is published in the morning, before 12:00 local time.
Each day, the absolute error of the OpenWindCast forecast and of the grid operator's own day-ahead forecast are compared on the same 11:00 target. The site reports the mean absolute error as a share of installed capacity (nMAE), the win rate, and, where official prices are available, the imbalance cost of bidding each forecast.
Benchmark forecasts, metered generation and installed capacity come from the grid operators: Energinet, Elia, Fingrid, Red Eléctrica, the four German TSOs, PSE, REN, NESO via Elexon, and EirGrid with SONI, mostly through the ENTSO-E Transparency Platform. Weather inputs come from Open-Meteo.
Yes. The dashboard and the daily verification record are public, and each zone's history can be downloaded as CSV from the forecast section. For anything else, email m.sahaf@live.com.