We will be installing a 40KW grid-tied PV system that uses PV modules wired in 
parallel as per the module manufacturer -- so it's a high amperage, low voltage 
system on the DC side. 2 branches of about 3KW of parallel wired modules each 
come together onto a DC bus. The DC branch conductors are sized as 2AWG.

The inverter system provided by the manufacturer consists of a number of UL1741 
single phase microinverters that all are powered off of the low voltage DC bus. 
So there's a bunch of microinverters in parallel, combined output is single 
phase power.

Those microinverters have a ground lug labeled "GEC". You know where this is 
going...

Assuming we are following NEC 690.47(C)(3), we'll be treating this ground as 
GEC and following all the GEC rules. My understanding is that because the DC 
conductors within the array are 2AWG (NEC 250.166(B), we will need to connect 
all 12 branches and 6 DC buses with continuous 2AWG and bring it all the way 
back 300' to where the AC GEC bond is located. We're getting a lot of pushback 
from the electrical sub and even some disagreement from the module manufacturer 
on this--no one's ever seen a grounding conductor of this size being required 
for this application.

Please don't get too bogged down with understanding the low voltage, parallel 
module spec and the massive number of microinverters involved. What I'm looking 
for is confirmation that I am properly understanding how the NEC GEC 
requirements apply, especially to the GEC size.

Charlie Pickard
NABCEP Certified PV Installation Professional T
Aladdin Solar, LLC



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