Quick Answer
Recommended wiring size for string inverters is typically 2 AWG for single-phase systems and 1 AWG for three-phase systems, considering a maximum distance of 200 feet between the array and the inverter.
Key Considerations for String Inverter Wiring
When selecting the proper wiring size for string inverters, several factors need to be taken into account. The most significant of these is the maximum current that the wiring will be subjected to during operation. The maximum short-circuit current of the PV array is used to determine the required wire size. For most single-phase string inverters, this value typically ranges between 25-40 amps.
Typical Wiring Requirements for String Inverters
The National Electric Code (NEC) recommends that PV array wiring be sized to handle 125% of the maximum short-circuit current. This means that for a 30-amp short-circuit current, the wiring size should be 37.5 amps minimum. Using a 2 AWG wire, which has an ampacity of 41 amps, meets this requirement.
Wire Gauge Selection for String Inverter Applications
In selecting the proper wire gauge for string inverter applications, it’s essential to consider the insulation type and temperature rating. For most PV array wiring applications, a 600-volt-rated wire with a -40°C to 90°C temperature rating is suitable. Using a 1 AWG wire, for example, provides an ampacity of 55 amps and can support 3-phase string inverter configurations, which typically require higher current ratings than single-phase systems.
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