Cables and Wiring

To make efficient use of the precious electricity made by either wind generators or solar modules (or stored in batteries), it is most important to choose cables and fittings carefully. The right cables of the correct cross-section should be used to ensure safety, reliability and to minimise voltage drop and energy losses.

Larger wire sizes are required in lower voltage DC systems than in standard AC systems.

All cables must be suitably sized and rated for the maximum voltage and current calculated for the circuit in question, taking into account any relevant derating factors such as installation method or grouping.

If in doubt consult equipment installation manuals or an electrician.

Cables should be clearly identified.

• This is important for safety since if wires are not labelled or correctly identified then if cut or unplugged there is a risk of damage electrocution or fire
• For service or troubleshooting cable identification and wiring schematics are essential both for safety, but also to make fault finding etc easier and quicker.
• DC cables in a PV array remain live during daylight and so all DC cables should be labelled ' PV array cable - live during daylight'

Wires should be marked according to the IEC Harmonised Cable Colour Codes:

Cables consist of conducting wires with a protective, insulating covering which must be resistant to moisture, sunlight, heat, chemicals and abrasion. For better protection underground, outside or in harsh conditions conduit or armoured cable must be used. For outside applications, cables and other exposed external plastic fittings must be weatherproof and resistant to deterioration in sunlight.

All cables should be adequately supported using conduit, cable cleats, cable clips or cable ties etc.

Flexible multi-stranded wire should be used instead of single stranded wire to ensure good connections and reliability.

Standard 230Vac household ‘twin & earth’ type wiring uses PVC insulation which is somewhat resistant to sunlight (it should last about 5 years), and this is the cheapest choice for internal wiring such as DC and AC load circuits. Common single insulated wires are not sunlight resistant.

The production, use and disposal of PVC results in the creation and release of large amounts of persistent toxic & carcinogenic chemicals, including dioxin - a hormone disrupter, one of the most toxic substances known.

By using polyethylene or rubber insulated cables (described as halogen-free cables) in place of PVC this environmental contamination can be avoided.