Load shifting for DUoS Red-band avoidance — how much is it worth
DUoS Red-band unit charges can be 20-40x Green-band rates. Which businesses can shift load out of the Red window, and how to calculate the real payback.
What DUoS is and why it has bands
Distribution Use of System (DUoS) charges are what the regional distribution network operator (DNO) bills your supplier for using the local grid. DUoS is time-of-use: Red, Amber and Green bands reflect network congestion. Red bands align with weekday peak demand — typically late afternoon and early evening — when the network is closest to capacity.
The size of the gap
The absolute pence-per-kWh in each band varies by DNO region and is refreshed each April. Across most regions the Red-band unit charge sits 20-40x higher than the Green-band charge, with Amber somewhere between. On a pass-through HH contract, every kWh you can move out of Red into Green shows up directly on the bill.
Who can actually shift load
Sectors with genuine flexibility: cold storage and refrigeration (pre-cool ahead of Red, coast through), water treatment, batch manufacturing where cycles can start earlier or later, EV charging fleets, and any site with battery storage. Sectors with almost no flexibility: retail, restaurants, healthcare, education during term time, and offices during business hours. Don't try to force a schedule change on a business whose customers set the load shape.
Calculating the payback
The straightforward calculation: identify your average kWh in the Red window per weekday, multiply by the DUoS Red/Green gap in your DNO region, multiply by ~250 weekdays. That gives an annual saving upper bound. Then subtract the operational cost of the shift — labour, wear on equipment cycling, any productivity loss — to get a realistic figure. The exercise is worth doing even at modest savings, because the answer usually points at a second lever: batteries.
Batteries change the maths
For sites without operational flexibility, a behind-the-meter battery can do the shifting artificially — charging in Green periods, discharging through Red. Payback horizons on commercial batteries have shortened materially as DUoS spreads have widened and battery costs have fallen. Whether it stacks up depends on your specific load and tariff, but the sums are worth running.
Fixed contracts vs pass-through
The catch: on a fully-fixed contract, DUoS is baked into your unit rate. You still get the network benefit (less peak demand = a slightly better supplier price at next renewal), but you don't get in-year savings from shifting. If you have real flexibility and enough scale, pass-through or partially pass-through contracts unlock the direct saving.
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