What does Curtailment mean?

Explanation

Curtailment means intentionally limiting or halting electricity consumption to prevent grid overload. In the context of EV charging, curtailment happens when the grid operator or site operator signals chargers to reduce power or shut down temporarily because the electrical system is approaching its limits.

Grid-level curtailment happens during extreme events: heat waves with massive air conditioning demand, cold snaps with high heating loads, or unexpected power plant outages. Site-level curtailment happens when the building or location approaches its electrical capacity limits. In both cases, EV charging is often among the first loads to be reduced because it can be paused without safety consequences.

For drivers, curtailment means your charging might be slower than expected, or in rare cases, temporarily unavailable. Smart charging systems handle curtailment gracefully, reducing power smoothly rather than cutting it abruptly. If you are at home, curtailment might delay your charging by an hour or two. If you are at a public charger, you might see reduced speeds during grid stress events.

Based on data from OpenADR Alliance.

Where you'll see this

• In charging network apps

Common confusion

Curtailment does not mean the grid is failing. It is a controlled, proactive measure to prevent problems. Your car and the charger handle it automatically, and your battery is not affected negatively.

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