The daily clock: D-1, D, D+10
Plan yesterday. Deliver today. Settle next week. Every single day.
The Swedish energy market runs on a clock that does not change. Same beats. Same times. Every day of the year. If you can name what happens at 12:00 CET on D-1 and what happens at hour-1 on the day of delivery, you can follow almost every meeting in the industry.
We walk through one full day, then list what each actor is doing at each beat.
The clock, in one timeline
flowchart TB
A([D-1, morning<br/>weather forecasts arrive<br/>traders update positions])
B([D-1, 12:00 CET<br/>day-ahead auction closes<br/>last chance to bid for tomorrow])
C([D-1, around 12:42 CET<br/>prices for tomorrow published<br/>one per zone per hour])
D([D-1 afternoon onward<br/>intraday market open<br/>continuous trading])
E([D, around 60 minutes before each hour<br/>that hour closes on intraday])
F([D, the delivery hour itself<br/>plants produce, reserves balance])
G([D+1 to D+12<br/>imbalance bills land])
A --> B --> C --> D --> E --> F --> G
style A fill:#fef3c7,stroke:#a16207,color:#713f12
style B fill:#fecaca,stroke:#b91c1c,color:#7f1d1d
style C fill:#fed7aa,stroke:#c2410c,color:#7c2d12
style D fill:#fed7aa,stroke:#c2410c,color:#7c2d12
style E fill:#fecaca,stroke:#b91c1c,color:#7f1d1d
style F fill:#fef3c7,stroke:#a16207,color:#713f12
style G fill:#fed7aa,stroke:#c2410c,color:#7c2d12
Three markets stacked in time, then one settlement window at the end. Nothing about this changes day to day.
What happens at each beat
| Time | What happens |
|---|---|
| D-1 morning | Forecasts update. Traders set their bids. |
| D-1, 12:00 CET | Day-ahead auction closes. After this, no more bids for tomorrow’s auction. |
| D-1, ~12:42 CET | Prices for all 24 hours of tomorrow published. One per zone. |
| D-1 afternoon onward | Intraday market opens. Continuous trading, around the clock. |
| D, 60 minutes before each hour | That hour closes for trading. The plan is final. |
| D, the hour itself | Plants produce. Reserves activate if needed. The TSO balances. |
| D+1 to D+12 | TSO measures the gap between plan and reality. Sends bills. |
A wind retailer, one full day
Walk through one day from inside a 200 MW wind portfolio in SE3.
- D-1, 09:00. Pull the morning forecast. Estimate wind production for tomorrow, hour by hour.
- D-1, 10:30. Submit bids to Nord Pool. Offer the forecast production at zero price (always wanting to sell).
- D-1, 12:00. Gate closes.
- D-1, 12:42. Prices published. SE3 will average 600 SEK/MWh tomorrow. Peak of 1,400 from 17 to 19.
- D-1, 15:00 onward. Intraday opens. As new forecasts arrive, trim positions hour by hour.
- D, 13:00. Forecast updates. Wind will drop early evening. Buy back 30 MWh on intraday for hour 17 to avoid being short.
- D, 16:00. Hour 17 closes on intraday. Plan is final.
- D, 17:00 to 18:00. Wind comes in 5 MWh below plan. Imbalance.
- D+10. Imbalance bill arrives. Owes 5 MWh times the imbalance price for that hour.
That same cycle runs every day, for every BRP, for every MWh.
Why the clock is so rigid
The clock is rigid because the rule from earlier is rigid. Generation must equal consumption every second. Bids have to close before delivery so plants can plan production. Forecasts have to update during the day so traders can adjust. Reserves have to be armed before the hour they might be needed.
Every fixed time on the clock is the answer to one question: when does the next set of information arrive, and who needs it next?
Next
Now two views of the data that engineers stare at all day. See Reading the data.