TNUoS transmission fees and preparing for the TRIAD period

28 October 2020

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TNUoS transmission fees and preparing for the 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.

What is 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 occasions been outside this window. 

Being prepared for a Triad period is essential as your usage during these periods can significantly impact the transmission charges that you subsequently have to pay. Speak to your power supplier to make sure they can offer Triad warning services and help you manage usage during these periods to maximise cost savings.

How can SEFE Energy help?

We provide flexible power products relevant to larger businesses. All charges are passed through for total transparency — including any TNUoS fees due — so you can immediately see the impact of any usage during the Triad period.

While Triad period fees might sound costly, there’s no need to worry about setting aside additional funds to cover any charges you receive during the period. Thanks to our transparent approach to obligatory fees and charges, you’ll always know when such charges come into effect.

prepare triad period

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.

Looking to control energy costs? We offer a range of flexible gas contracts for large organisations.

Find out more about what we can do for you


To alleviate the financial strain of paying transmission fees, we’re able to provide warnings which alert you of an upcoming Triad period. These alerts could give you enough time to reduce the amount of electricity you use and therefore avoid paying transmission fees, although this isn’t guaranteed.

By cutting down on your energy use, you’ll effectively reduce the overall electricity demand on the National Grid — which will in-turn help to reduce the amount your business is charged.

You can sign up to our Triad warning service here. Once part of this, you’ll receive alerts throughout the winter (when demand is at its highest) — giving you plenty of opportunities to reduce your electricity consumption.

If you have any further queries about Triad periods and transmission charges, please don’t hesitate to get in touch with our Forecasting Team. 

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