DC arc fault
A high-energy arc in DC wiring — a yield loss and a fire risk.
A DC arc fault is a sustained electrical discharge across a gap or poor connection in a plant’s DC wiring, often the end-state of corroded connectors or damaged insulation. Unlike AC, the DC arc does not self-extinguish, so it is both a generation loss and a serious fire hazard — the most safety-critical fault in the PV fault library.
Symptoms
- Intermittent string dropouts or erratic current preceding a hard fault.
- Evidence of connector overheating, discolouration, or burning at inspection.
- Arc-fault circuit interrupter (AFCI) trips on the affected string or inverter.
SCADA signatures
- Erratic, high-frequency current/voltage noise on a string before failure.
- Repeated unexplained string trips clustered on one combiner or connector run.
- A step loss following the earlier signature of rising series resistance.
Root cause
Usually the terminal stage of progressive series resistance: corroded MC4 connectors, loose terminations, or rodent- or UV-damaged insulation create a gap that the array’s DC voltage arcs across. Because a DC arc is self-sustaining, what began as a small underperformance can escalate into a high-energy, fire-capable event.
Financial impact
Beyond the lost generation from the tripped string, an unaddressed DC arc is a genuine fire risk to the asset and to personnel — the cost ceiling is the plant, not the string. This is the fault where early detection of the precursor (rising resistance, connector heating) pays for the entire monitoring programme.
How NuraVolt detects it
NuraVolt treats the connector-degradation pathway as a continuum: it tracks the rising series resistance and string-current deficits that precede an arc and escalates them as safety-critical, so the corroded connector is replaced before it reaches the arcing stage rather than after.
Frequently asked questions
See also
Falling insulation resistance on the DC side — a safety-critical fault.
A string delivering less current than its peers under the same irradiance.
Power-stage overheating from cooling failure or a blocked heat sink.
Where DC arc and insulation fault codes are surfaced.
See this on your own plants
NuraVolt turns your SCADA and BMS data into early fault detection, degradation-aware BESS analytics, and audit-ready reporting. A fixed-scope audit shows you what we’d find on your portfolio.