Solar cables on PV plants during high temperatures

Solar cables in photovoltaic (PV) plants are critical components that must withstand harsh environmental conditions — especially high temperatures. Here’s a focused overview on the behavior, challenges, and considerations for solar cables operating under high temperatures in PV plants:

🔥 Impact of High Temperatures on Solar Cables

1. Thermal Aging & Insulation Degradation
   • Prolonged exposure to high temperatures accelerates insulation degradation (e.g., cross-linked polyethylene, rubber, or halogen-free compounds).
   • UV exposure + heat can cause cracking or embrittlement in subpar cable jackets.
2. Current Carrying Capacity (De-rating)
   • Ampacity decreases with temperature rise. Cables rated at 90°C, 105°C, or even 125°C must be de-rated if ambient temperatures exceed 30°C.
   • Example: At 60°C ambient, a cable may only carry ~70–80% of its rated current.
3. Resistance Increase
   • Copper/aluminum conductors have positive temperature coefficients — their resistance increases with heat, reducing efficiency and increasing I²R losses.
4. Mechanical Properties
   • Extreme heat can soften insulation, reducing abrasion resistance and increasing risk of damage during movement or vibration.

✅ Design and Installation Considerations

1. Cable Selection
   • Use solar-specific cables (e.g., EN 50618-compliant H1Z2Z2-K or UL 4703 cables).
   • Ensure temperature ratings of at least:
     • -40°C to +90°C for continuous operation.
     • Up to +120°C for conductor under overload conditions.
2. Proper Derating Calculations
   • Factor in ambient temperature, cable bundling, installation method (direct burial, tray, conduit), and solar irradiance when calculating ampacity.
   • Refer to standards: IEC 60287 (for buried/ducted cables), NEC Table 310.15(B)(2)(a) (for U.S.).
3. Ventilation and Layout
   • Avoid bundling too many cables together.
   • Use cable trays with adequate ventilation or install underground with appropriate soil thermal resistivity.
   • Avoid direct contact with hot metallic surfaces.
4. Monitoring and Maintenance
   • Use thermal cameras or sensors to monitor cable hot spots in large-scale PV farms.
   • Inspect periodically for signs of insulation cracking, discoloration, or melting.

🌞 Summary Table