What is the difference between solar cable and battery cable?

Solar cable is a single-core, UV-stabilised cable rated for high DC voltages up to 1000VDC. It is used between solar panels, combiner boxes, and inverter MPPT inputs where voltage is high and current is moderate per string. Battery cable is a highly flexible, multi-strand cable rated for very high currents at low voltage between the battery bank and inverter DC input. SP-Energy stocks 6mm solar panel wire for panel-to-inverter runs and 35mm grey battery cable for battery-to-inverter runs.

Why is 6mm the standard solar cable size for residential systems?

A standard 400W to 550W solar panel produces approximately 10A to 13A per string at open circuit. A 6mm cross-section cable handles up to 50A on short runs with minimal voltage drop and stays within the safe current rating for most residential single-string and dual-string arrays. For arrays with very long cable runs or higher-current configurations, 10mm cable may be required to keep voltage drop within acceptable limits.

Why do battery cables need to be 35mm when solar cables are only 6mm?

Battery cables carry low voltage at very high current. A 5kW inverter on a 48V battery bank draws over 100A at full load. A 6mm cable cannot safely carry 100A DC — it would overheat and could cause a fire. A 35mm cross-section cable is the minimum safe size for battery-to-inverter runs on 5kW to 8kW systems. Always verify the inverter manufacturer's recommended cable cross-section for your specific model before ordering.

Can I use solar cable for battery wiring?

No. Solar cable is not rated for the high current levels present in battery-to-inverter wiring. It is also less flexible than battery cable, which makes it harder to route cleanly in tight spaces behind wall-mounted inverter and battery enclosures. Use 35mm battery cable for all battery-to-inverter connections and 6mm solar cable for all panel-to-inverter DC string runs

Do I need to protect my battery cable with a fuse?

Yes. South African solar installation standards and most inverter warranties require a DC fuse on the positive battery cable between the battery terminal and the inverter input. The fuse protects the cable from a short circuit current that can exceed several thousand amps in the event of a fault. SP-Energy stocks 125A and 160A DIN fuses in the Solar Electrical range for this purpose. Size the fuse for the cable's current rating, not the inverter's rated output.

Can I run my solar system and protect my home during an outage using these cables?

Correctly sized and installed solar cables do not affect whether your system operates during an outage — your hybrid inverter and battery bank handle that. What cables do affect is long-term system safety and efficiency. Undersized solar cable causes voltage drop that reduces daily energy yield. Poorly terminated battery cable connections cause resistance heating that degrades inverter terminals over time. Correct cable sizing is the foundation of a safe, long-lasting installation.