Why Use Larger Cable? Low-voltage power systems with inverters can have very high current through the cables that connect the inverter to the batteries. Large AC loads like microwave ovens, toasters, irons, and washers can cause an inverter operating on a 12 VDC battery system to draw over 100 A. Large motors may draw 300 to 500 A during startup. When cables between batteries, and from the battery bank to the inverter, are too small the current available to the inverter is limited and it may fail to supply larger loads. Properly sized cables also impose less resistance, reducing voltage drop, and thereby help maximize system efficiency.
Circuits protected by 250 A breakers or 400 A fuses should use 4/0 AWG cables. Use 2/0 AWG cables for 175 A breakers and 200 A fuses. Use 2 AWG cables for 110 A or smaller fuses or breakers.
Array Cables and Connectors
Grid-tie modules generally ship with attached cables that are listed to UL 1703 with the module. The cable connectors on these are fully waterproof when connected, touch-protected and designed for up to 1,000 VDC and 30 A, but cannot be safely disconnected when under load.
Our output cables are made with 10 AWG PV Wire and can be used in solar arrays up to 1,000 VDC. All of our array output cables are made with PV wire that is listed to UL 854, which is required by the NEC for use with transformerless inverters.
Additionally, we stock the MultiContact Solarline 2 MC4 and Amphenol H4 crimp-on connectors for use with 10 AWG PV stranded wire. Proper crimping to the wire and insulator assembly requires special crimping and assembly tools.
As most experienced PV installers will attest, good wire management is a hallmark of high-quality installations, and its lack can lead to inspectors and customers alike looking for other potential issues. Cables and wires should be kept off the roof or ground and water should not be allowed to pool at the entrances of enclosures, splices and junction boxes. Given that a solar PV system is designed to last for 25 years or more, it is vital to use wire-management hardware that will hold up in the environment and allow deployment with minimal strain on the components.