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Charging and methodology

These pages contain details about the charges that users of the electricity transmission system have to pay, how they are calculated and what changes are currently being considered by the industry. We do not charge household consumers directly. Please contact your supplier for any domestic queries.

Transmission network use of system (TNUoS) charges

TNUoS recovers the cost of installing and maintaining the transmission system. TNUoS tariffs are published by 31 January and take effect from 1 April each year.

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Balancing services use of system (BSUoS) charges

Recover the cost of day-to-day operation of the transmission system. Generators and suppliers are liable for these charges, which are calculated daily as a flat tariff.

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Electricity connection charges

Recover the cost of installing and maintaining connection assets that are not normally used by any other party. Charges are calculated every January and charged monthly.

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Assistance for areas with high electricity distribution costs (AAHEDC)

Replaces an earlier arrangement, commonly referred to as “Hydro Benefit”. The North of Scotland is currently the only area specified to receive assistance.

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Network charging developments and Charging Futures

Our work considering a Targeted Charging Review and how we are working with Ofgem and others to ensure a coordinated approach with other network charging initiatives.

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Transmission charging methodology forum (TCMF)

Established under the CUSC, the aim is to provide a forum for regular discussion between interested parties and National Grid on development of the charging methodologies.

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Charging policy and guidance

Includes open letter consultations and guidance, charging methodology policy decisions, electricity industry information guides, and Triads data.

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Transmission losses

During the transmission of electricity, some energy is 'lost' from the transmission system, usually in the form of heat. This lost energy is known as transmission losses. Transmission network losses result from the transport of power between power producers and grid supply points through transmission infrastructure equipment, such as power transformers, overhead lines, cables, and switchgear. We have a duty, as part of our licence obligation, to report on transmission losses. We publish an annual transmission losses report along with a strategy that sets out how we intend to deal with losses.

As part of the Electricity Incentives consultation, Ofgem proposed replacing the old financial incentive on transmission losses with a reputational incentive. This reputational incentive acknowledges that National Grid only manages around three per cent of the total energy on the system through the balancing mechanism (BM), and therefore its limited control over the level of losses.

By removing the financial incentive, it removes the possibility of windfall gains and losses due to market developments beyond our control. These market developments could affect the level of transmission losses, which therefore affects our performance against the incentive scheme and BSUoS charges.

Under the new scheme, we are required to report on any actions taken in which we consider transmission losses and system transmission losses more generally. This information can be found in the Monthly Balancing Services Statement 

We are also required to report on the level of transmission losses and expected impact of market developments. This information can be found in our Electricity Ten Year Statement (ETYS). The Transmission Losses Strategy and annual Transmission Losses Report are to be used in conjunction with the ETYS.

Connection and Use of System Code

The Connection and Use of System Code (CUSC) is the contractual framework for connection to, and use of, the National Electricity Transmission System.

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CUSC modification guidance and documents

CUSC modification proposal forms, guidance on how to complete them, and the latest progress report and modification register. 

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