Technical
What Is Curtailment?
The intentional reduction of power output from a generator, often required when there is more electricity supply than demand. Renewable energy curtailment is a growing challenge as solar and wind capacity increases.
Curtailment happens when the grid cannot absorb everything a plant could produce — because demand is low, transmission is congested, or prices have gone negative. Grid operators instruct (or price signals induce) wind and solar plants to back down first, since they can ramp instantly and have no fuel to save. California's spring solar surplus and West Texas wind congestion are the canonical US examples.
Some curtailment is economically rational — building occasional surplus is often cheaper than building transmission to capture every megawatt-hour. But rising curtailment rates erode project revenues and are a leading argument for two fixes: transmission expansion and battery storage, which converts surplus midday solar into evening supply.
Related terms
Part of the CleanPowerDaily Clean Energy Glossary — 12 in-depth explainers and 50 defined terms. Definitions are free to cite with attribution.