DUoS Charges Explained: How to Cut Your Red Band Costs

How Distribution Use of System charges work, why the red, amber and green time bands matter, and how UK businesses can cut their peak-time spend.

DUoS Charges Explained – Most of a modern electricity bill is no longer the electricity. It is the cost of moving it. DUoS charges are a large slice of that, and unlike the wholesale price they follow a timetable you can actually work around. Get the timing right and the same site can pay noticeably less for the same kilowatt hours.

The catch is that DUoS rarely appears as a single tidy line. It is spread across your bill, dressed up in industry shorthand, and most businesses never see how much of it they could move. That is a shame, because for a half-hourly site it is one of the more controllable costs going.

What DUoS Charges Actually Are

DUoS stands for Distribution Use of System. It is the charge levied by your regional distribution network operator, the company that owns the local wires, substations and transformers that carry power the last leg of its journey to your meter.

There are fourteen of these networks across Great Britain, each a regional monopoly regulated by Ofgem. They do not sell you energy. They charge your supplier for the use of their network, and your supplier passes that cost straight through to you. So while the line on the bill comes from your supplier, the underlying rate is set by the network operator and is the same whoever you buy your power from.

DUoS is separate from the transmission charge, TNUoS, which covers the national high-voltage grid. The two are often lumped together as network costs, but they behave differently and respond to different actions.

The Red, Amber and Green Bands

The part that matters most for half-hourly sites is the time-of-use structure. DUoS unit rates are split into three time bands, usually called red, amber and green.

Red is the expensive band. It covers the network’s busiest hours, typically a window on weekday late afternoons and early evenings when everyone is drawing power at once. The red rate can be many times the green rate for the same unit of electricity.

Amber sits in the daytime shoulders either side of the peak, at a middle rate. Green covers nights, early mornings and weekends, when the network is quiet and the rate is low.

The exact hours and prices vary by region and change each April, so a London site and a site in the North West face different windows and different numbers. But the shape is the same everywhere. Use power in the red band and you pay a premium. Shift it into green and you pay a fraction of that.

Why the Timing Is Worth Money

The whole point of the banding is to discourage demand at peak, when the network is closest to its limits. For a business with any flexibility in when it runs, that creates a clear opportunity.

Move a load out of the red window and the saving is not marginal. A site that habitually runs energy-hungry processes through the early evening peak is paying top rate on every one of those units. Pull that activity back by an hour or two, or push it into the night, and the DUoS element of those kilowatt hours drops sharply.

This is the same logic that drives demand side response, and the two stack neatly. The actions that earn you flexibility payments often cut your red-band DUoS at the same time, so a single change to your operating pattern pays twice.

The Capacity and Fixed Elements

DUoS is not only about unit rates. A half-hourly bill also carries a DUoS capacity charge, levied per kVA of agreed supply capacity per day, plus a fixed daily standing charge.

The capacity element ties straight back to your agreed supply capacity, the same figure that drives your kVA charges. If that capacity is set higher than your site genuinely needs, you are overpaying on the DUoS capacity charge as well, on top of the supplier capacity charge. Right-sizing the figure cuts both at once.

There can also be an excess capacity charge if your demand pushes past the agreed level, so this is an area to measure rather than guess. The aim is an agreed capacity set just above your real peak, with a sensible margin, not a round number nobody has checked in a decade.

Batteries and Load Shifting

The cleanest way to dodge the red band without disrupting the business is to move the energy, not the work. That is exactly what on-site storage does.

With battery storage you charge during the cheap green hours overnight and discharge through the red peak, so the site keeps running normally while drawing far less from the network when it is most expensive. The DUoS saving becomes one of several revenue and saving streams that help fund the battery, alongside flexibility payments and wholesale price arbitrage.

Even without a battery, simple changes help. Rescheduling shift patterns, pre-cooling cold storage before the peak, staggering plant start-ups and shifting electric vehicle charging to overnight all chip away at red-band consumption for little or no capital outlay.

Getting Your DUoS Charges Under Control

As with most network costs, it starts with the data. Twelve months of half-hourly readings show exactly how much of your consumption falls in the red band and what it is costing you. Until you can see that, any saving is theoretical.

From there it is a question of what you can realistically move and whether the operational change is worth the reduction. For some sites the red-band spend is small and not worth chasing. For others, particularly energy-intensive operations running through the early evening, it is a standing cost they could cut every single month.

DUoS is best handled as part of a wider look at your energy procurement and network charges, rather than in isolation, because the levers overlap. Catalyst analyses where your consumption sits across the DUoS bands, models what shifting load would save, and helps put the changes in place without creating problems elsewhere. If you run a half-hourly supply and have never looked at your red-band exposure, ask our team for a review.

Related service: Non-Commodity Costs, how Catalyst helps businesses understand and reduce the network and policy charges hidden in their energy bills.

Further reading: TNUoS Charges Explained looks at the transmission half of your network costs and why it rose sharply in April 2026.

Further reading: Capacity Market Charges Explained covers the winter peak levy, which like DUoS Red-band charges rewards businesses that move demand out of weekday evenings.

Further reading: Business Electricity Standing Charges Explained breaks down the fixed daily cost that sits on every electricity bill alongside DUoS.