Saturday: Utility-Scale Solar: DC Arc Faults Don't Stop
A continuous plasma arc is just one mistaken MC4 pull away in utility solar.
The Core Issue: Modern utility-scale solar farms operate at up to 1500 Volts DC.
The Lesson: Alternating Current (AC) crosses zero volts 120 times a second, which naturally helps extinguish electrical arcs. Direct Current (DC) does not. If an MC4 connector is pulled apart under load, or a cable is pinched, it will draw a continuous, extremely hot plasma arc.
Actionable Takeaway: Never disconnect PV string connectors under load. Always open the combiner box switch or inverter disconnect first to stop the current flow.
Post Conclusion
Failure Mode — Do Not Ignore This post describes a failure mode or active hazard. Do not ignore the warning signs described.