The shape of Spain's negative-bid curve changed entirely in 2025.

2024: compact, symmetric around -12 EUR/MWh

2025: long downward tail, median at -20, extremes past -100

First few GWh drop steeply. Then a flat, brutal tail stretches right. More volume. Worse prices. The merit order didn't just shift. It deformed.

Solar PV drove the expansion during peak production hours.