User Manual

Planning for a Three-Phase IQ Microinverter System – North America

Ampacity Calculations for Three-Phase Feeders to 208Y/120V Solar Subpanel

Calculate the ampacity of the three-phase, 208Y/120V solar subpanel feeders from the continuous output

power rating as follows:

# of Microinverters ∗ Inverter Continuous Output Power Rating = Total Continuous Output Power

Total Continuous Output Power / 208𝑉 / 1.732 = Solar Subpanel Continuous Ampacity

IQ 6 (208V)

IQ 6+ (208V)

Continuous Output Power Rating

230VA

280VA

For a solar subpanel with 231 IQ 6+ Microinverters, the continuous output current rating is:

231 ∗ 280𝑉𝐴 = 64,680𝑉𝐴

64,680𝑉𝐴 / 208𝑉 / 1.732 = 179.54𝐴

NEC Article 690.9(B) requires a 125% factor be applied to the continuous output current for sizing

overcurrent protection of the branch circuit:

179.54𝐴 ∗ 1.25 safety factor = 224.4𝐴

A 225A overcurrent protection device (OCPD) is required for 231 - IQ 6+ Microinverters at 208Y/120V.

208Y/120V Electrical Schematic