DC arc faults occur at loose plug connectors, damaged cables, corroded contacts, or broken cell interconnects within solar modules. With temperatures exceeding 3,000°C, they are one of the most common causes of fire in photovoltaic systems.
Unlike AC arcs, DC arcs do not extinguish at the zero crossing of the voltage. Once ignited, a DC arc can burn for hours as long as sufficient solar irradiation is available. The DC side of a PV system cannot be de-energized during daylight hours.
Arc Fault Circuit Interrupters (AFCI) per UL 1699B detect the characteristic high-frequency spectrum of an arc and disconnect the circuit. Since 2018, AFCIs have been mandatory for PV systems in the United States; in Germany they are recommended. PV-BESS-Assessor systematically evaluates all potential arc-fault sources during fire cause investigations.
AFCIs are currently not legally mandated in Germany but are recommended by VdS (insurer loss prevention) and in DIN VDE 0100-712. In insurance claims due to arc-fault fires, the absence of AFCIs is increasingly discussed as a breach of duty of care.
DC Arc Fault: EUR 127,000 Fire Damage to 180 kWp Rooftop System
Real anonymized investigation case with measurement data, timeline, and economic evaluation.