What is a DUoS capacity charge on a business electricity bill?

A DUoS capacity charge is a distribution network charge on agreed or authorised supply capacity, in pence per kilovolt-ampere (kVA) per day, where the tariff includes it [S1]. It differs from time-banded unit and fixed charges. Exceeding the agreed limit can add excess capacity charges [S1]. Check the site’s tariff and supplier contract, not just whether its meter records half-hourly data.

Last checked 26 October 2026

A DUoS capacity charge is a charge for agreed or authorised electricity supply capacity, expressed in pence per kilovolt-ampere (kVA) per day on applicable business tariffs [S1]. Half-hourly-settled sites should distinguish it from red, amber and green unit charges and fixed charges [S1]. Ofgem’s Targeted Charging Review (TCR) moved residual cost recovery to fixed charges, so reducing electricity use does not automatically remove that component [S2].

How is the capacity element calculated?

Use this formula for a tariff quoting pence per kVA per day [S1]:

Capacity cost in pounds = agreed kVA × published pence/kVA/day × billed days ÷ 100.

Enter your own tariff inputs and billing dates. This guide gives no example rate: request the current statement for your distribution network operator (DNO), charging year and tariff identifier. Keep a copy beside the invoice so a rate change cannot be mistaken for a capacity change.

Check authorised supply capacity against the connection agreement. Ask the supplier whether network costs are included in its price or passed through separately. Avoid counting a separately itemised component again within an all-in unit rate.

How do capacity, unit and fixed charges differ?

Source: NGED East Midlands, effective April 2026 [S1]. MIC means Maximum Import Capacity; MEC means Maximum Export Capacity. The statement also lists reactive power charges [S1]. These are network components, not the complete retail electricity price.

For scheduling questions, use DUoS red, amber and green. Ask your supplier which differences your contract passes through before valuing a change in charging times.

What happens when demand exceeds authorised capacity?

Request the supplier’s excess-capacity calculation and underlying demand records, then compare the period and capacity with the connection agreement. Have an electrical designer review the peak and proposed EV charging schedule before requesting any change. A billing calculation does not establish that cables or switchgear can safely carry additional load.

Use half-hourly metering and DUoS charges to organise the data request. Ask the designer to show how any proposed load management would enforce the agreed operating limit.

What did Ofgem’s Targeted Charging Review change?

TCR addressed residual charges: the part recovering fixed costs of the existing network. Ofgem decided these should be recovered through fixed charges for households and businesses [S2]. This is distinct from the capacity charge calculated on agreed kVA.

NGED explains that reducing MIC does not automatically move a site into a lower residual band. Reallocation depends on the conditions in DCUSA Schedule 32 [S3]. Request separate assessments of any proposed capacity reduction and residual-band review. Ask for the applicable evidence requirements and effective date in writing.

Why can a half-hourly meter have a high standing charge?

Ask the supplier to itemise what its standing charge includes. Compare the fixed network component, capacity and any metering or data-service costs separately, using the actual contract. A single daily total cannot show which part would change if you reduced capacity or consumption.

Before adding chargers, solar or batteries, gather the current agreement, tariff, bills and representative interval records. Ask the supplier and designer to price the proposed operating arrangement rather than extrapolating from another site’s standing charge.

Next step

Prepare your records with the site check, then get matched with an installer that covers your area.

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