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. This page counts the hours per month where the Serbia bidding zone (RS) 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 RS bidding zone, bucketed in market time (Europe/Berlin).
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.
RS)Free, no API key required. Sub-second response from a locally cached Parquet store.