On the 9th December for the first time in history, the UK experienced a negative day ahead trading prices for 03:00AM to 04:00AM delivery on the hourly day-ahead auction dropping to -£2.84/MWh.
The cause was record levels of wind generation. Across the weekend of 7th and 8th December, wind generation was exceptional, with a peak of 16.2GW recorded. As a proportion of demand, wind generation averaged 38.3% over 8th December with the peak recorded at 41.6%.
High wind output carried into the early hours of 9th December and combined with low levels of demand, saw day-ahead hourly prices between 3:00AM and 4:00AM reach -£2.84/MWh. This followed the trend already seen for in-day trading, with 27 settlement periods showing negative pricing across 7th and 8th December. The greatest was seen for imbalance prices, which dropped to a low -£88.00/MWh and stayed below zero for 23 consecutive periods across 7th and 8th December.