What the day-ahead to imbalance spread is, and is not
A position closed at the day-ahead gate settled at the day-ahead price. Whatever was left open settled at the imbalance price for the quarter-hour it fell in. The difference between them is what carrying a position past the gate was worth per MWh, and it is the link between the auction views on this console and the balancing ones.
On this page
The two prices, side by side
The same delivery day priced twice: once by the auction, once by the system after every gate had closed. Both as published, on the same delivery periods, with no model between them. Where the lines separate, closing a position at the auction and leaving it open were materially different decisions.
Resolution differs between the two publications, and the view aligns them on the periods they share rather than interpolating one onto the other. A day where they could not be put beside each other says so rather than drawing a spread it cannot support. The folded ledger contains every delivery quarter-hour, including unpaired periods shown as N/A. CSV exports include both prices, the spread, the match resolution, UTC period timestamps and the time of the read. An empty response is an unconfirmed read; it does not prove that a price was never published.
The spread, against the imbalance that drove it
Imbalance price minus day-ahead price, drawn over the system's own position. A system that turned out short usually pays above the auction and one that turned out long usually receives below it, so the two moving together is the ordinary case rather than the notable one.
The system imbalance rides as a bar strip below the plot, in MW on its own scale. The axis label belongs to the spread line alone, and the legend says so: the two are never read off the same axis.
A price difference, not a cost
This is the exposure of one MWh left open past the gate. It is not anyone's settlement figure. What a participant actually paid depends on the position they held, and neither of these publications carries positions.
Nothing on this view attributes anything to a participant, and nothing on it is screened. The ranked table of the widest quarter-hours is an ordering of one delivery day against itself: no threshold is applied and nothing fires. It is there to point at the periods worth reading, not to assert anything about them. Each ranked period links to its settlement replay with the date and UTC quarter-hour preserved. Links beside a selected period also open its merit order, and the charts mark that period. The view is named Day-ahead vs imbalance because these publications do not reveal what positions were left open.