The market types in detail
A battery can serve several markets — but not all at once. Here are the sub-markets of the British power system, from Day-Ahead to reserves and capacity. They are hourly ALTERNATIVES, not stackable revenues.
Day-Ahead market (N2EX / EPEX SPOT)
The reference market: daily auction on N2EX (Nord Pool) and EPEX SPOT for the 24 hours of the next day — the base of every arbitrage calculation. Since Brexit, GB clears its own Day-Ahead price (decoupled from EU coupling).
Intraday market (continuous)
Continuous adjustment after the Day-Ahead: trades up to shortly before delivery, at finer granularity.
Balancing Mechanism (NESO)
Near-real-time balancing run by the system operator NESO — the British equivalent of the real-time market, in the final hour before delivery.
Imbalance settlement
Deviations between schedule and outturn are settled at the imbalance price — which makes the quality of imbalance settlement decisive.
Frequency response (FCR / DC)
Primary frequency response (FCR; in GB the Dynamic Containment family): capacity reserved to stabilise frequency at 50 Hz, paid on capacity.
Secondary reserve (aFRR)
Automatic reserve (aFRR): controlled activation to restore balance area by area.
Manual reserve (mFRR)
Manually activated reserve (mFRR): capacity mobilised on the system operator's instruction.
Capacity Market
The Capacity Market pays for guaranteed availability in peak periods; in Great Britain it is run through T-4 and T-1 auctions overseen by the government and the regulator.
Revenue stacking — alternatives, not additive
At hourly level, these markets are ALTERNATIVES: the same MWh cannot serve arbitrage AND reserve at the same time.
Sources and regulation
The regulatory detail of each market falls under British law and is not asserted here in general terms.
References
Day-Ahead and intraday wholesale markets: Nord Pool (N2EX) and EPEX SPOT (GB) — each exchange clears its own GB Day-Ahead price (decoupled from EU coupling since Brexit). Balancing Mechanism, frequency response and reserves: NESO (National Energy System Operator). Regulatory framework and Capacity Market: Ofgem. The regulatory detail evolves — to be verified against the primary sources. Rules summary: /gb/rules/.