# Arc-Fault Detection (AFCI)

A protective function that monitors the DC circuit for the electrical signature of an arc caused by a damaged conductor or a loose connection, and shuts the inverter down when it detects one. It is required on PV DC circuits above a defined voltage in several jurisdictions.

Source: https://inverterdata.com/en/glossary/arc-fault-detection/
Site: InverterData (inverterdata.com) — open technical specification database
Last updated: 2026-08-24
License: free to quote with attribution to inverterdata.com

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DC arcs are the specific fire hazard of PV systems: unlike alternating current, direct current does not cross zero, so once an arc starts it tends to sustain itself, and a PV string behaves as a current source that will keep feeding it without tripping a fuse. Detection works by listening for the characteristic broadband noise an arc injects into the circuit. Nuisance trips do occur — inverter switching noise, nearby radio transmitters and some optimiser topologies can mimic the signature — but a repeating arc-fault alarm should be treated as a genuine wiring fault and investigated, never simply reset.