Cable Selection Basics
Proper cabling is essential for safety and efficiency in PV systems. Undersized cables cause voltage drop, energy loss, and potential fire hazards due to overheating.
Key Cable Types
- PV Wire (PV1-F / H1Z2Z2-K): Double-insulated, UV-resistant, rated for 1,500V DC. Required by NEC for array wiring.
- THHN/THWN-2: Building wire for AC circuits inside conduit. Rated for 600V, 90°C wet/dry.
- Battery Cables: Fine-stranded copper, flexible, high ampacity. Often 2/0 to 4/0 AWG for battery interconnects.
Voltage Drop Calculation
Voltage drop Vd = (2 × L × I × R) / 1,000 where L = one-way length (ft), I = current (A), R = resistance (Ω/1,000ft). NEC recommends ≤3% total drop from array to inverter.
Color Coding
DC: Red (+), Black (-), Green/bare (ground). AC (120/240V split-phase): Black (L1), Red (L2), White (neutral), Green/bare (ground).