GB electricity prices: which are free and when each is known
This page lists the prices that a battery in Great Britain (GB) faces, which of them are free to download, and when each becomes known. National Energy System Operator (NESO) is the system operator. The page is background for the battery and solar separation study. How a battery responds to the prices is described on how GB batteries schedule themselves.
A battery faces several prices. Several free prices are known only after delivery, and three are known before delivery. The free prices known before delivery are the N2EX day-ahead price, the response and reserve auction results, and the bid-offer prices. The table lists the prices that a battery model can use. Modo Energy's explainer describes the day-ahead and intraday markets, and Elexon describes imbalance pricing.
| Price or dataset | Run by, and time resolution | Free to download? | Known when |
|---|---|---|---|
| Day-ahead, N2EX hourly auction (NESO dataset) | NESO publishes it, hourly | Yes | About 10:00 the day before |
| Day-ahead, EPEX 30-minute and hourly auctions, and intraday auctions (Nord Pool GB auction) | EPEX, half-hourly or hourly | No (EEX webshop, from €665 a month) | 15:45 the day before, for the 30-minute auction |
| Market index (MID, the EPEX short-term index) | Elexon, half-hourly | Yes | After trading |
| System price and net imbalance volume | Elexon, half-hourly | Yes | Indicative about 30 minutes after the period, revised in later settlement runs |
| Bid-offer prices and acceptances | Elexon, per acceptance | Yes | Bid-offer prices before the period, acceptances during it |
| Response and reserve auction results (Dynamic Containment, Moderation, Regulation, Quick Reserve, and Balancing Reserve; Enduring Auction Capability (EAC)) | NESO, the daily 14:00 auction; results | Yes, from November 2023 | The afternoon before delivery |
The final settled volumes arrive months later. Elexon's settlement runs rerun the figures several times. The Final Reconciliation (RF) run comes 14 months after the day, and a later Dispute Final (DF) run follows at 28 months. A study of the past can use the final figures, and a forecast made on the day cannot.
Day-ahead prices vary widely within the year. The Electricity Maps 2025 review gives a 2025 day-ahead mean of £81.2 per MWh, a range of −£30.5 to £958.5, and 190 negative hours (141 in 2024). A negative price means that producers pay to sell.
Day-ahead prices are moderately predictable, and imbalance prices are hard to predict. The predictability statement is our judgement from the two papers below. Lago et al. found that the best models in their benchmark reduce relative mean absolute error to 0.40 to 0.61 of a same-hour-last-week rule, in studies without GB data (source not checked). Browell and Gilbert report that day-ahead forecasts of imbalance prices beat a benchmark by only 3% and intraday forecasts by 5% to 40%, mostly within 3 hours (source not checked). A battery's scheduling software (its optimiser) needs the shape of the day's price curve more than the level. The shape is the price rank of each half-hour (Maciejowska et al.).