A negative day-ahead price means generators pay to keep delivering — it happens when wind and solar output plus inflexible generation exceed demand and the surplus cannot be exported or stored. Sweden is split into 4 bidding zones, each clearing independently — figures below are for the default reference zone, Sweden 3 (Stockholm) (SE_3). This page counts the hours per month where the Sweden 3 (Stockholm) bidding zone (SE_3) cleared strictly below zero on the day-ahead auction — at-zero hours are not counted. Hourly resolution, bucketed by calendar month in market time, from 2015.
Monthly counts of strictly-negative day-ahead hours in the SE_3 bidding zone, bucketed in market time (Europe/Berlin).
Sweden has 4 bidding zones — each clears its own day-ahead price, so the count of negative-price hours differs by zone. Pick a sub-zone:
An hour counts as negative only when the day-ahead clearing price is strictly below zero — at-zero hours are excluded, because a price of exactly €0.00/MWh is semantically different from producers paying to deliver. Markets that clear in 15-minute intervals are aggregated to hourly first, so the metric counts negative hours, not negative quarters. Months are bucketed in market time, so DST-shift months keep their real hour counts.
Negative-price hours are the single biggest driver of capture-rate compression for solar and wind: they cluster in exactly the hours those technologies produce most.
SE_3)Free, no API key required. Sub-second response from a locally cached Parquet store.