Daily guide · ES · 2026-08-06
Charging an EV in Spain this week: what the prices actually said
All numbers computed from the week's published auction results at publication and frozen — this article is an honest snapshot, not a page that rewrites itself. Reproduce via the API.
The gap between midday and evening prices was the defining feature of the week. The cheapest charging windows, all falling in the early afternoon, averaged 37,90 EUR/MWh, while evening peaks averaged 146,55 EUR/MWh. That is a 74 percent difference between the best and worst times to plug in, and it held every single day.
The midday troughs went further than usual. On 1 August the window averaged 0,46 EUR/MWh, and on 2 August it turned negative at -0,14 EUR/MWh, while evening prices those days still sat at 144,80 and 123,85 EUR/MWh respectively. Solar output pushes daytime prices down to almost nothing, then the market tightens sharply after sunset. Even the weaker days, such as 3 August at 81,92 EUR/MWh, stayed well below their evening levels of 164,65 EUR/MWh.
The concrete takeaway: charge in the early afternoon, roughly between 12:00 and 14:00, and avoid the evening entirely. For a household drawing 150 kWh a week, shifting to those windows was worth 16,30 EUR this week, or about 847 EUR over a year.
Every day at 13:00 CET, an auction sets electricity prices for every hour of tomorrow — separately, for each European bidding zone. Those prices routinely differ by a factor of two to three within a single day, because solar floods the middle of the day and demand peaks in the evening. If you charge an EV, that spread is money: the car doesn't care when it charges, only that it's full by morning. This is what the spread looked like in ES this week.
74%
cheaper to charge in the best 3h window than at the evening peak, on average this week
37.9 vs 146.55
€/MWh: best window vs 18–21h evening habit (week average)
≈€847
a year on the wholesale component, for 150 kWh/week of charging at this week's gap
Day by day: when the cheap window actually fell
| Day | Cheapest 3h window | Window avg €/MWh | Evening 18–21h | Gap |
|---|---|---|---|---|
| 2026-07-30 | 12:00–15:00 | 17.06 | 155.94 | −89% |
| 2026-07-31 | 14:00–17:00 | 76.92 | 144.29 | −47% |
| 2026-08-01 | 13:00–16:00 | 0.46 | 144.8 | −100% |
| 2026-08-02 | 12:00–15:00 | -0.14 | 123.85 | −100% |
| 2026-08-03 | 13:00–16:00 | 81.92 | 164.65 | −50% |
| 2026-08-04 | 13:00–16:00 | 81.08 | 156.07 | −48% |
| 2026-08-05 | 14:00–17:00 | 7.98 | 136.23 | −94% |
Local time. Notice the window MOVES — sometimes after midnight, sometimes midday when solar peaks. A fixed night tariff catches some of this; following the auction catches all of it.
Automate it in ten minutes
You don't need to read auction results at 13:00 every day — ask the API for the cheapest window and let your wallbox follow it. One call:
curl -X POST -H "Authorization: Bearer YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{"zone": "ES", "duration_minutes": 180}' \
https://voltcast.com/api/v1/optimize/cheapest-windowHome Assistant users: the Voltcast integration exposes the same window as a sensor you can automate against; evcc users get a ready-made tariff config. The Home plan (€9/mo) covers one zone of your choice with 7-day forecasts — the free tier lets you test everything on DE-LU first. And if you want to charge on a forecast of tomorrow before the auction even publishes, that's the P50 curve — scored publicly every day so you know exactly how much to trust it.
Method & citation. Prices are hourly means of published day-ahead auction results (native 15-minute periods averaged; ENTSO-E/SMARD, attributed). Wholesale-price component only — grid fees and taxes come on top and vary by supplier. Cite as "Voltcast Research, voltcast.com/guides/ev-charging-es-2026-08-06".
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