Balancing Services Use of System
The charge that recovers the cost of balancing the national transmission system in real time; restructured in 2023 to be paid by generators only on the demand side.
BSUoS recovers the cost incurred by the national system operator (NESO) in keeping the transmission system in real-time balance — frequency response, reserve, reactive power, constraint management and so on. Historically, BSUoS was paid half-and-half by generators and demand customers and was charged as a half-hourly volumetric pence-per-kWh adjustment that varied substantially by settlement period.
From April 2023, Ofgem's BSUoS reform moved the demand-side share to a fixed daily charge calibrated annually, removing the half-hourly volatility that previously made BSUoS one of the harder cost components to budget for. The customer-facing implications:
- BSUoS is now a more predictable cost, set once per year.
- Real-time demand-side management for BSUoS avoidance no longer applies — the cost is independent of when within the day you consume.
- Suppliers should pass BSUoS through transparently rather than bundling it into a forecast unit-rate adder.
For procurement, the change has reduced one source of basis risk in fixed contracts and made flexible contracts somewhat easier to compare against fixed alternatives.
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Distribution Use of System
DUoSThe charge electricity suppliers pay to regional Distribution Network Operators for using local distribution wires; recovered from customers through the unit rate.
Read definitionTransmission Network Use of System
TNUoS / TUoSThe charge for using the high-voltage national transmission grid, recovered from suppliers and ultimately from customers.
Read definitionTargeted Charging Review
TCROfgem's reform of how residual transmission and distribution network costs are recovered; replaced volumetric Triad and DUoS residual charges with fixed bands.
Read definitionHalf-Hourly Metering
HHThe metering and settlement regime in which electricity consumption is measured and settled in 30-minute intervals; mandatory above 100 kW measured maximum demand.
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