Every weekday at 12:55 CET, a piece of software in Paris closes the most important auction in your household budget. Four minutes later, it publishes 24 numbers. Those numbers — one for each hour of the next day — are what your dynamic tariff will pass through to your bill, plus a small margin, plus tax. If you have a dynamic contract, the auction at 12:55 is, literally, tomorrow's price.
This piece is a walkthrough of what happens in those four minutes, why the numbers come out the shape they do, and what the household reading this can do with that information.
The day-ahead market, in one paragraph
Every generator in north-west Europe — every wind farm, every gas turbine, every nuclear reactor, every battery — submits a bid: how many megawatt-hours they will supply, at what minimum price, for each hour of tomorrow. Every retailer submits the mirror: how many MWh they need to buy, at what maximum price. The auction sorts the supply bids from cheapest to most expensive, the demand bids from most willing to least, and finds the point where the two curves cross. That crossing point is the clearing price. Everyone who bid below it sells; everyone who bid above buys; everyone settles at the same price.
This happens 24 times, once per delivery hour. The auction is run on the European platform SDAC, with EPEX SPOT as the Dutch hub. By 13:00 CET the results are public. By 16:00 they are in your supplier's billing system.
Why the curve has a shape
The clearing price for any given hour is set by the marginal generator — the most expensive plant whose bid still made the cut. When wind is abundant and demand is low, the marginal plant might be a wind farm willing to sell at €5/MWh just to capture the subsidy. When demand spikes and wind is calm, the marginal plant is the most expensive gas turbine in the stack, possibly at €400/MWh. The day's twenty-four numbers therefore trace, in a recognisable shape, the balance of three forces: load (which peaks in the morning and evening), solar (which floods the middle of the day), and wind (which arrives in multi-day waves, indifferent to the clock).
On a windy Sunday, the curve flattens. On a still, cold Tuesday in January, it carves two cliffs — one at 08:00, one at 18:00 — that can be ten times the daily trough.
Reading tomorrow's curve, as a household
By 16:00 CET your supplier's app, or any of the free public dashboards, shows the next day's 24-hour curve. Most Dutch households who run a dynamic contract develop, within a month or two, the habit of glancing at it once — typically with the evening news. They are looking for three things, in order:
- The trough. The cheapest hour. For most weeks in 2026 this lands somewhere between 02:00 and 05:00, occasionally around 13:00 on heavy solar days. This is where flexible load goes — the EV, the dishwasher, the dryer.
- The spread. The gap between trough and peak. A spread of €0.05/kWh is not worth a behaviour change. A spread of €0.30/kWh is worth setting an alarm.
- The shape of the evening peak. If the 18:00–20:00 block is sharp and tall, it is worth pre-heating the house at 16:00 and coasting through dinner with the heat pump throttled.
What does not matter
Two myths worth dispelling. First, the cheap hour is not always the middle of the night. On heavy-solar days in spring and summer, midday is cheaper than dawn. Second, the price curve is not arbitrary; it is the system's clearest possible signal of when the grid is stressed. A €0.45 hour is not a punishment. It is the market telling you that the marginal source of energy right now is a gas turbine running at thin margins, and that the next kilowatt-hour you consume will burn methane and emit CO₂ — both of which someone, somewhere, would prefer you didn't.
The four minutes, demystified
Inside those four minutes between 12:55 and 12:59, the SDAC algorithm — a piece of optimisation software called Euphemia — solves a continent-wide problem with about 200,000 bid blocks and 50 zonal constraints. The constraint that matters most for Dutch consumers is the interconnector capacity to Germany and Belgium. When that capacity binds, Dutch prices decouple from German prices and the curve looks different from what the wind forecast alone would suggest.
This is not trivia. It is why, on otherwise identical days, the Netherlands sometimes clears at €0.18 while Germany clears at €0.04 — and why a contract that indexes to the Dutch zone behaves differently from one that indexes to a European average.
What to do with this
If you have a dynamic contract: glance at the curve once a day, at the end of the day, and let the trough do the work for you. If you do not yet have one: the wizard above takes your usage shape and asks the more useful question — given the way your household actually consumes, what would the last 365 days of EPEX clearing prices have done to your bill?
