National Grid ESO has published the Triad dates for 2019/20.
- Monday 18 November, 17:00-17:30
- Monday 2 December, 17:00-17:30
- Tuesday 17 December, 16:30-17:00
Triads are the three highest winter evening peaks, at least ten days apart.
National Grid uses the methodology to determine transmission network charges for large companies.
The more power companies are using on these dates, the bigger their bill. For some, the difference can be seven figures.
National Grid ESO only reveals Triad periods retrospectively, so companies switch to onsite generation or significantly reduce grid draw when they think a Triad is likely.
The effect is to dampen demand on cold evenings across winter, creating headroom on the system.
Triad is being removed as part of an overhaul of network charging by regulator Ofgem.
See the data here.