DUoS Charges Explained

Who Sets DUoS Charges and Why

There are 14 Distribution Network Operators across England, Wales, Scotland, and Northern Ireland. Each one manages electricity distribution in their region. These include companies like UK Power Networks, Northern Powergrid, and Scottish Power Distribution.

These DNOs don’t set their charges in isolation. Ofgem (the Office of Gas and Electricity Markets) regulates them. This means DUoS charges are monitored to ensure they’re fair and that money collected is actually spent on maintaining and upgrading the network, not on inflating company profits.

The reason DUoS charges vary by time of day is straightforward economics. The network infrastructure has a maximum capacity. During peak times—typically early morning, late afternoon, and early evening—the network is most strained. Running transformers and cables harder shortens their lifespan and requires more expensive infrastructure upgrades. By charging more for peak-time usage, DNOs incentivize businesses to shift consumption to quieter periods when the network has spare capacity.

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How DUoS Is Calculated

DUoS charges are based on two things: the amount of electricity you use during peak times, and the maximum demand you place on the network at any single point.

Your maximum demand is measured in kilowatts (kW). Let’s say you run three large refrigeration units simultaneously—the moment you switch them all on, your demand might spike to 15 kW. That peak demand gets recorded, and it’s one of the factors determining your DUoS bill.

The calculation works like this: the DNO charges a certain pence per kilowatt-hour for usage during peak periods, and a lower rate for off-peak usage. But they also charge a standing charge (a daily fee) that partially relates to your registered capacity—essentially paying for the right to draw that maximum amount.

If you have a half-hourly smart meter (increasingly common for businesses), the DNO can see exactly when you used electricity and charge you accordingly. Without a smart meter, they’ll estimate your usage patterns or work from your contract’s deemed profile.

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The Time Bands

DUoS charges are divided into three time bands, often called Red, Amber, and Green:

Red (Peak): This is the most expensive rate. Red period typically runs from 4 PM to 7 PM on weekdays during winter months. This is when the network faces its highest demand—factories, shops, offices, and households are all consuming power simultaneously. Businesses should prioritize shifting flexible loads away from this window.

Amber (Shoulder): Mid-priced. Amber covers shoulder periods like early morning or late evening, roughly 7 AM to 4 PM and 7 PM to 11 PM on weekdays. These hours still see moderate demand but nothing like peak. If you can’t shift to Green, Amber is the second-best option.

Green (Off-Peak): The cheapest rate. This runs from 11 PM to 7 AM every day, plus all day weekends and bank holidays. Night-time usage and weekend consumption face the least network strain, so the DNO charges significantly less.

The exact times shift seasonally. Winter definition (roughly November to March) has stricter peak windows because heating demand raises network usage. Summer definition spans April to October with slightly different timings.

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What DUoS Costs

DUoS charges vary by region and by how much peak capacity you use. There’s no single answer—it depends on your DNO and consumption profile.

For a small office with relatively flat usage, DUoS might add 2-4 pence per kilowatt-hour on top of your unit rate. For a business with heavy peak-time consumption, you could see 5-7 pence per kWh or more, depending on your demand level.

Here’s a practical example: imagine a company with an annual consumption of 50,000 kWh. Their breakdown might be 60% usage during Amber periods, 30% during Green periods, and 10% during Red periods. With Red charged at 6p/kWh, Amber at 3p/kWh, and Green at 1p/kWh, their total DUoS bill would be approximately £1,200 annually. That’s roughly 2.4p per kWh on average. But a business using 15% during peak Red would see roughly £1,650 instead—a difference of £450 per year.

Location matters too. Rural areas with less dense infrastructure often have higher per-unit DUoS rates to cover the cost of maintaining fewer customers across larger distances.

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Can You Reduce DUoS Charges

Yes, but not by reducing the amount you consume overall. You can’t eliminate DUoS—it’s a network access fee. What you can do is shift when you consume.

The most effective approach is time-of-use optimization. If your business has flexibility—say, you run energy-intensive machinery, charge vehicles, or operate cold storage—scheduling that work for off-peak or shoulder periods cuts your DUoS bill significantly.

Some businesses achieve reductions of 20-30% in their DUoS component by moving peak consumption. Freezer companies, for instance, might pre-cool storage units in the afternoon and let them coast through peak evening hours. Manufacturing facilities can schedule non-urgent production runs for nights or weekends.

If you have control over your maximum demand, that helps too. A business drawing 12 kW constantly faces higher charges than one with the same annual consumption but a lower peak draw. Load-spreading—avoiding switching on all energy-intensive equipment simultaneously—keeps your registered demand lower.

Demand-side response programs also exist. Some DNOs offer financial incentives to businesses that reduce consumption during stressed network periods. You won’t get paid much, but it can offset some DUoS costs.

Finally, ensure you’re on the right tariff. Some suppliers bundle DUoS into a single rate, while others pass it through as a separate line item. Understanding your contract structure helps you spot whether you’re overpaying or missing the benefit of usage flexibility.

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How DUoS Appears on Your Bill

DUoS charges show up differently depending on your contract type.

Pass-through contracts list DUoS as a distinct line item. You’ll see something like “DUoS charges” or “Distribution costs” broken down by time band (Red, Amber, Green usage at different rates). This transparency makes it easy to spot where costs come from and negotiate with your supplier.

Bundled contracts incorporate DUoS into the unit rate. Your supplier gives you a single pence-per-kilowatt-hour price, and that figure already includes their estimated DUoS costs plus profit. With bundled pricing, you won’t see the DUoS breakdown explicitly.

Neither is inherently better—it depends on your situation. Pass-through contracts shield you from supplier markup on DUoS but expose you to price volatility if rates change. Bundled contracts offer price certainty but can end up more expensive if your actual DUoS usage doesn’t match the supplier’s estimate.

Check your latest bill now. If you see a line mentioning DUoS, pass-through, or distribution charges broken by time band, you’re on a pass-through contract. If it’s just a single unit rate with no breakdown, it’s bundled.

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Key Takeaways

✓ DUoS charges cover the cost of maintaining your local electricity distribution network and are set by your regional DNO under Ofgem regulation.

✓ You pay different rates depending on when you use electricity: peak (Red) is most expensive, shoulder (Amber) is moderate, and off-peak (Green) is cheapest.

✓ Peak periods roughly align with 4-7 PM on winter weekdays, but exact times vary seasonally and by region.

✓ Most businesses can’t eliminate DUoS, but shifting consumption away from peak times can reduce your bill by 20-30%.

✓ Your DUoS charges appear as either a pass-through line item or bundled into your unit rate, depending on your contract type.

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DUoS is one of several network charges on your business energy bill. The other major one is TNUoS (Transmission Use of System), which covers the high-voltage national grid rather than your local distribution network. Together, they make up a significant portion of what you pay beyond your unit rate.

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