PV plants must run 25 years outdoors, and harnesses are among the first parts the environment attacks. Poor connections age in 5-8 years and become hot-spot hazards.
1. UV: cross-linked jackets are the dividing line
Ordinary PVC cracks under UV. Use cross-linked polyolefin (PV1-F class) wire with UV aging test data.
2. Thermal cycling: -40°C to +90°C
Thermal swings of 60°C+ loosen crimps. Use MC4-class locking sealed connectors and verify with thermal cycling.
3. Water and salt spray
Require IP67+ at outdoor joints; coastal plants need salt-spray-rated plating and housings, and drip loops inside combiner boxes.
4. DC-specific current sizing
Size DC runs at 1.25x string current; DC arcs sustain more easily than AC, so 100% inspection and quality connectors are non-negotiable.