Triads are the top three half-hourly peaks of national energy demand across the grid, separated by ten clear calendar days, over the most energy intensive period of the year: November to February. National Grid confirms these peaks after the season, at the end of March. Typically, triads occur when high business demand meets the domestic mid/late afternoon tea-time period, causing an overall spike in energy use.
How Triads impact your energy bill
To manage the huge demand on the network during the triad periods, the National Grid imposes a Transmissions Network Use of System (TNUoS) charge. This is used to finance the maintenance of the UK’s electricity grid to ensure future supply. Impacting customers with half-hourly meters, the charge is proportional to a business’ energy use over the triad periods (the three half hours of highest demand) and is linked to their location. If a business doesn’t consume electricity in the three Triad periods, they don’t pay HH (half-hourly) TNUoS charges for the entire financial year.
As standard, we include a charge for 85% of your maximum demand figure for TNUoS on our customer bills. After the final triads are announced, we issue the March invoices to show the triad periods and make any reconciliations.