In one line
US electrical code requirement that residential solar systems de-energize within 30 seconds of an emergency shutoff signal.
What it means
Rapid shutdown is a US National Electrical Code requirement (NEC 690.12) that residential PV systems reduce conductor voltages to under 30V within 30 seconds of a shutoff signal — protecting firefighters and emergency responders. Implementation uses module-level power electronics (microinverters, DC optimizers) or string-level rapid shutdown devices. The 2017 NEC update tightened the requirement to module-level; most 2026 US residential systems use Enphase or SolarEdge equipment to comply natively.
Related terms
Browse every term in the renewable energy glossary, or read the latest analysis on Inverters & power electronics.