Daily guide · NO4 · 2026-07-31
Charging an EV in Norway Tromsø 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.
Prices in Tromsø stayed low across the week, but the pattern still rewarded timing. The cheapest charging windows averaged 4,59 EUR/MWh, against an evening peak average of 9,07 EUR/MWh. That gap of 49 percent is the headline: charge in the right window and you roughly halve the energy component of your session compared with plugging in during the evening.
The windows themselves moved around, so a fixed habit will not consistently land the cheapest hour. On 26 July the window average fell to 0 EUR/MWh, starting at 03:00, while 27 July offered little advantage at 8,08 EUR/MWh in a window beginning at 13:00. Several of the best windows sat overnight or in the early hours, but midday windows appeared too, as on 24, 27 and 28 July. The evening was reliably the more expensive period every day.
The concrete takeaway: at 150 kWh per week, shifting from evening to the cheap window saved 0,67 EUR this week, or about 35 EUR over a year. The absolute saving is modest at these price levels, but the discipline of avoiding the evening peak is what carries value when prices climb.
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 NO4 this week.
49%
cheaper to charge in the best 3h window than at the evening peak, on average this week
4.59 vs 9.07
€/MWh: best window vs 18–21h evening habit (week average)
≈€35
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 |
|---|---|---|---|---|
| 2026-07-24 | 14:00–17:00 | 7.48 | 12.15 | −38% |
| 2026-07-25 | 21:00–24:00 | 4.23 | 9.98 | −58% |
| 2026-07-26 | 03:00–06:00 | 0 | 8.89 | −100% |
| 2026-07-27 | 13:00–16:00 | 8.08 | 8.6 | −6% |
| 2026-07-28 | 13:00–16:00 | 2.88 | 7.84 | −63% |
| 2026-07-29 | 00:00–03:00 | 4.95 | 6.31 | −22% |
| 2026-07-30 | 04:00–07:00 | 4.53 | 9.69 | −53% |
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": "NO4", "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-no4-2026-07-31".
The monthly European power roundup
Negative-price records, the biggest spreads, which zones were hardest to forecast — every number computed from our production data, on the 2nd of each month. No filler, unsubscribe anytime.