Comments and suggestions on planned wiring, please?

I’d appreciate any feedback on my solar array wiring plan. I’ve done lots of residential wiring back in the day, but solar is new to me. Delta county, Colorado is using the 2017 NEC.

I’ve got twelve 310 watt REC panels with Enphase IQ7+ microinverters on a ground mount 50’ from a 200 amp service entrance mounted on a garage that feeds a 200 amp main subpanel in the house. The PV panels are mounted to the rails and ground mount (1 1/2” galvanized schedule 40) with UL2703 listed bonding connectors. The microinverters will produce a total of 14.42 amps max continuous @240 volts in optimal conditions.

I’ll run #10 THHN/THWN wire in 3/4” PVC schedule 40 (schedule 80 above grade?) from a weatherproof box on the array to a 30 amp weatherproof disconnect switch, then to a 20 amp backfeed 2 pole breaker in the service entrance panel mounted farthest from the main breaker on the bus. I’ll install two CU plated ground rods at the array (dry, rocky soil here) with #6 CU wire grounded to one of the Snapnrack panel mount rails. The Snapnrack ground mounting instructions were specific on connecting the EGC to just one rail. The ground mount itself has a total of 18’ of concrete encased pipe in the ground, but there’s no single 10’ section, so I don’t think I can call that a ground electrode (NEC 250.52), although it certainly helps. Finally, I’ll enclose the back of the array with hardware cloth.

I’m a bit hazy on grounding to the house system-do I need to run a #12 or #10 grounding wire from the service entrance panel to the array? There’s nothing else along the way to ground (these microinverters do not require a ground or even have a ground connection) except for the metal disconnect box which is mounted just below the service panel. As stated earlier, the array, panels, rails, etc will all be grounded to several ground rods at the array.

Any comments and suggestions would be appreciated. BTW, total cost for the system so far is a bit less than $7K.

Thanks,

rcourtem
3720 watts, REC panels, enphase IQ 7+
Delta, CO

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