A rooftop solar system has two very different wiring sides, and each needs the right cable. The DC side runs from the solar panels to the inverter and carries direct current in harsh rooftop conditions. The AC side runs from the inverter to your distribution board and behaves like normal house wiring.
DC side — solar (PV) cable
Use a purpose-made solar / PV cable, not ordinary house wire. It is double-insulated, UV- and weather-resistant, rated for high DC voltage (typically 1.5 kV DC) and works over a wide temperature range so it survives years of rooftop sun and heat.
| System size | Typical string current | Common DC cable size |
|---|---|---|
| Up to 3 kW | up to ~10 A | 1.5 sq mm |
| 3–5 kW | ~10–18 A | 2.5–4 sq mm |
| 5–10 kW | ~18–30 A | 4–6 sq mm |
AC side — house wire
From the inverter to the AC distribution board, size the cable to the inverter’s rated output current, just like a normal circuit. As a rough guide a single-phase 3 kW inverter (~13 A) suits 2.5–4 sq mm copper; a 5 kW inverter (~22 A) typically needs 4–6 sq mm. Provide proper earthing and a dedicated MCB/RCCB for the solar circuit.
Indicative guidance for typical Indian domestic installations. Always confirm final cable sizes against the applicable IS standards, your local wiring rules and a licensed electrician for your specific installation.