Intraday market — after the auction, reality drifts
Author
Volton Editorial Team
Date Published
The intraday market is the continuous order book that opens after the day-ahead auction closes and runs until close to physical delivery. It exists because forecasts are wrong: wind farms produce more or less than scheduled, generators trip, loads surprise. BRPs use intraday to clean up the gap between schedule and reality before imbalance prices apply.
The day-ahead auction sets a price. Reality drifts. The intraday market exists because reality drifts.
A storm front lands east of where the forecast said it would. A factory reschedules a shift. The wind picks up over the North Sea. By the time the noon auction ink is dry, somebody on the grid is already in a position they did not plan for, and the intraday market is where they go to fix it before it costs them.
Intraday opens right after the day-ahead clears and runs continuously until close to delivery — on the Estonia–Finland border, cross-zonal trading closes 30 minutes before the delivery interval, with intra-zonal trades possible closer still. ACER adopted 30 minutes as the EU-wide standard in December 2025. Unlike the day-ahead market, it is not a single auction with one clearing price. It is a live order book. Bids and offers post in real time, the best matching pair trades, and the next quote moves the price. Minute by minute, the market re-prices the next few hours of electricity as new information arrives.
The mechanics are easier to see through three actors. A wind farm that expected 50 MW at 14:00 but is now metering 60 MW can sell the extra 10 MW intraday rather than carry it into imbalance. A retailer whose customers are consuming less than the load forecast suggested can buy back the surplus it locked in yesterday. A battery operator, watching spreads widen between 18:00 and 19:00, can shift volume between the two hours and pocket the difference. None of that is possible in a once-a-day auction.
Cross-border trading on intraday runs through XBID, the European single platform that lets an order from Tallinn match against a bid in Lisbon as long as the transmission capacity exists. ENTSO-E calls the wider arrangement SIDC, the Single Intraday Coupling, and the volumes routed through it have grown fast every year since launch. Nord Pool operates the regional intraday venue that plugs Estonia, Latvia, Finland and the rest of the Nordics and Baltics into that European book.
This is where flexibility actually pays. A battery struggling to earn its keep in day-ahead, where it gets one bid per hour and competes against everything in the merit order, suddenly has something to sell on intraday: the ability to react to volatility on a timescale others cannot match. Wind farms with imperfect forecasts would be hammered by imbalance prices without intraday; instead they re-bid every few hours and arrive at the gate close to flat. The auction-versus-continuous-market distinction looks like plumbing, but it is doing more work than it looks. It is what makes a high-renewables grid financially survivable.
Volton is a Nord Pool member and a registered Balance Responsible Party at Elering, which means we are on the intraday book ourselves, every day, re-bidding the wind and solar in our portfolio as forecasts shift through the afternoon. By the time gate closure hits, the position should be as close to flat as the weather allows. The hours after that, the seconds even, belong to the balancing markets further down the ladder.
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