TNUoS transmission fees and Triad period

Customers and generators pay transmission fees (TNUoS) to National Grid each year in order to maintain and upgrade the UK electricity grid. The amount you have to pay is calculated by monitoring your usage during the period 1 November – 28 February - the Triad period.

Triad is the term used to describe the three periods during any given year when National Grid anticipate overall demand to be highest. This will equate to the three highest half hour (HH) settlement periods between 1 November and 28 February, separated by a clear window of 10 days between each. Historically Triads have occurred most often between the hours of 17:00 and 18:00, as industry and domestic power usage tend to peak, however they have on occasion been outside this window.

In all likelihood, most of our business energy customers won’t notice when TNUoS transmission fees are incurred during the Triad period. However, some businesses, particularly ones that use a large volume of electricity, may be charged at a higher rate during a Triad period.