Daily guide · SI · 2026-08-31

Negative-price watch Slovenia: this week's floor, and what's ahead

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.

This week's floor in Slovenia landed at -0,74 EUR/MWh, recorded on 30 August 2026 in the hour ending 13. That midday timing is the familiar signature of solar-driven oversupply, when generation briefly outpaces domestic demand and pushes the market below zero. The floor itself is shallow, only marginally under the zero line, so this is a watch rather than an alarm.

Across the week, prices fell negative in 5 hours and sat below 10 EUR/MWh in 7 hours. The narrow gap between those two counts tells you that once prices soften here, they tend to fall the rest of the way rather than lingering in the low single digits. For the year to date, Slovenia has now logged 1.002 negative periods, so the structural context remains one of recurring soft midday pricing.

The concrete takeaway: the maximum probability of a negative price over the next seven days reads 0, meaning our model sees no repeat priced in for the days ahead. Treat this week's dip as an isolated midday event, and keep attention on the 13:00 window when negative risk does return.

When wind and solar produce more than a zone can consume or export, the day-ahead auction clears below zero — producers literally pay consumers to take power. Negative prices went from curiosity to structural feature across Europe, and for anyone with flexible load or storage they're the most interesting hours of the year. Here's where SI stands.

-0.74

this week's floor (€/MWh), 2026-08-30 at 13:00 local

5 / 7

hours below €0 / below €10 this week

1,002

negative delivery periods in 2026 so far (SI)

The forward view

Our negative-price risk model (Brier-scored daily against climatology — record on /accuracy) currently puts the peak probability of a sub-zero period in SI over the next 7 days at 0%. That number updates daily via GET /v1/risk/negative/SI — a 14-day calendar of per-15-minute probabilities.

Never miss one again

The useful pattern isn't watching a dashboard — it's a webhook that fires when tomorrow's auction clears negative anywhere in your zone:

curl -X POST -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"event": "negative_prices", "zone": "SI", "url": "https://your-app/hook"}' \
  https://voltcast.com/api/v1/webhooks

It delivers seconds after the 13:00 CET publication, HMAC-signed. Journalists and analysts: the live SI tracker has the all-time records, monthly history and a CSV download — free to cite with attribution. For the systematic view (which hours, which seasons, how deep), the full 2015+ archive is one bulk export away.

Live SI prices → All daily guides → Start with Home →

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/negative-watch-si-2026-08-31".

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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.