The operating model spans four layers: policy sets direction, regulation enforces it, operators plan and dispatch, and markets settle the outcome. Each layer has its own actors, timescales, and incentives.
Four swim lanes, from political direction at the top to market settlement at the bottom. Vertical coordination arrows show where the layers must talk to each other.
A day in the life of the electricity market
Time
Phase
Actor
System
What happens
D-1 11:00
Day-ahead auction
Generators + suppliers
EPEX/N2EX
Market clears at single price
D-1 to gate closure
Intraday trading
Traders
Continuous market
Parties adjust positions
Gate closure (1 hr before)
Balancing Mechanism
NESO control room
BM system
NESO accepts bids/offers
Real-time
Dispatch
NESO
SCADA/EMS
Frequency held at 50 Hz
D+1 to D+14 months
Settlement
Elexon
SAA system
Metered vs contracted volumes reconciled
Who does what on a normal day?
A day in the life of the GB electricity system runs through four phases. Each phase involves different actors working to different deadlines, but all depend on the output of the phase before.
Day-ahead
D-1, by 11:00
Market clears and the plan takes shape
Generators submit availability declarations to NESO. NESO publishes its demand forecast. The wholesale market clears day-ahead prices, setting the baseline for the next trading day. Interconnector nominations are finalised, locking in cross-border flows.
Intra-day
D-1 to gate closure
Forecasts sharpen, trading continues
Trading continues in the intra-day market as forecasts are refined. NESO updates its wind and solar output predictions. If the forecast diverges materially from the day-ahead position, balancing actions begin. Parties adjust their contracted positions to reduce their imbalance exposure.
Real-time
Second by second
NESO dispatches and the system balances
NESO dispatches generation and demand second by second. Frequency is maintained at 50 Hz within statutory limits. Constraint management is active across the transmission network. If a generator trips or wind drops unexpectedly, reserve services are deployed to restore balance.
Settlement
Up to 14 months later
Elexon calculates who owes what
Elexon calculates imbalance positions for every settlement period. Generators and suppliers are paid or charged based on the difference between their metered output and their contracted position. The settlement process runs through multiple iterations, with final settlement occurring up to 14 months after the delivery day.
Where does coordination break down?
The operating model works well within each layer. The weak points are at the boundaries, where different organisations with different incentives must share information and align decisions.
Transmission-distribution interface
NESO plans transmission. DNOs plan distribution. But distributed generation, including rooftop solar and batteries, now affects transmission flows in ways that were not anticipated when the boundary was drawn. Coordination between the two levels is improving through initiatives like the Open Networks programme, but it remains fragmented. A solar farm connecting at 33 kV can change power flows at 132 kV, and the two planning processes do not always catch that interaction in time.
Gas-electricity coupling
Gas-fired generators are the main source of flexible electricity generation in GB. When the gas network faces constraints during cold weather, the electricity system loses access to that flexibility. The two networks are planned and operated by different organisations under different regulatory frameworks. A cold snap that strains the gas system can limit electricity generation at the same time that heating demand peaks. This coupling is well understood but not well coordinated.
Data sharing gaps
Real-time data flows from smart meters to suppliers to Elexon for settlement. But not all of that data reaches NESO or DNOs in time to inform operational decisions. DNOs are only now gaining visibility of what is happening on their low-voltage networks. Market-wide Half-Hourly Settlement (MHHS) will improve the data picture, but full visibility across the system is still years away.
What are the structural tensions in the model?
The operating model contains genuine tensions that cannot be resolved by better coordination alone. These are design trade-offs built into the structure of the system.
Centralised planning vs market competition
NESO plans the network centrally, identifying where capacity is needed and proposing reinforcement. But generation investment is market-driven: developers choose where to build based on resource availability, planning consent, and expected revenue. The two processes do not always align. The result is a connections queue full of projects in areas where the network was not designed to accept them.
Central network planvsMarket-led investment
Speed vs due process
Governance processes, including code modifications, licence consultations, and impact assessments, exist to ensure fairness and scrutiny. But the climate emergency demands faster decisions on infrastructure, market design, and system operation. The system cannot have both unlimited consultation and rapid deployment. Every governance reform that speeds things up reduces the time available for challenge and review.
Thorough governancevsRapid deployment
Consumer protection vs investment incentive
The energy price cap protects consumers from excessive prices. But it also limits supplier margins and can discourage investment in innovation, customer service, and new market entry. The same tension appears in network regulation: tight price controls keep bills down but may slow the pace of network investment needed for decarbonisation.
Consumer protectionvsInvestment incentive
What is gate closure?
Gate closure is the point, currently one hour before the start of a settlement period, after which generators and suppliers cannot change their contracted position. Before gate closure, parties can trade in the intra-day market to adjust their positions. After gate closure, NESO takes full responsibility for balancing the system and dispatches generation or demand response to match supply and demand in real time. The one-hour window is a compromise: shorter would give NESO less time to act; longer would reduce trading flexibility.
Why does settlement take 14 months?
Settlement takes 14 months because metering data must be collected, validated, and reconciled across millions of meters, hundreds of suppliers, and thousands of generators. Initial settlement runs occur within days, using estimated data. Subsequent runs use progressively more accurate metered data. Disputes must be resolved and data corrections applied. The final reconciliation run at 14 months is the point at which all financial positions are considered final. The MHHS programme is expected to reduce this timeline, but the core challenge of data quality and dispute resolution remains.
Current position
The GB operating model can respond quickly in real time, but longer planning, consenting, and governance loops move at a different speed. That difference matters because the transition depends not only on balancing today's system securely, but also on bringing future capacity, networks, and reforms into service on time.
Current position
Gas and electricity remain operationally linked because gas still supports power generation and heating demand shapes wider winter system conditions. That is why adequacy, storage, interconnection, demand flexibility, and the future role of gas all continue to feature in whole-system resilience planning.
Methodology and sources
Last reviewed: 17 March 2026
This page describes the operating model as it functions in practice. It draws on published procedures and regulatory documents, interpreted through the lens of how the system works day to day rather than how it is formally described in legal text.