Appreciate help with a few details of my 5.0 kW GT ground mounted system

cbid

New to the forum, though I have been reading for a while. My husband and I are self-installing a ground mounted GT system that is a "buy all-sell all"/FIT type setup with our utillity. For background, we recently gutted an old home and completely rewired it ourselves, including installing a new service entrance, new 200 amp panel, all indoor wiring (we have electric appliances including 2 mini spilts for heating and cooling), etc and passed all of our inspections of the first try, so we do have some electrical experience. This is our first PV project. We have 20 Isofoton ISF-250 modules and we are using the SMA 240-US micro inverters with a Multigate XT2E. We have already installed a Patriot Post Driven Ground mount racking system, so will have two arrays of 10 modules each. Our Multigate, AC Disconnect and dedicated 100 A PV meter with it's own service entrance will be on the side of the house about 50 feet from the close end of the arrays. Our existing 200 A meter is adjacent to where we will mount the PV meter on the side of the house.

The SMA 240-US system is approved to be installed as an ungrounded system and I just want to be sure that I am understanding the implications of that for all of my wiring. In our state, we are still under 2011 NEC for residential. The solar permitting system in pretty unsophisticated here so far. There are no detailed permitting applications or plan reviews required by our AHJ. We did submit a one line drawing to our utility for interconnection which was approved, but it's the three line that is giving me pause--I am not required to submit one, but obviously, I have to have one in my head to get this all to work, right?

So, here are some of the things about which I would appreciate feedback/guidance:

Since SMA micro inverters are approved as ungrounded, I am planning not to run a bare copper EGC from micro inverter to micro inverter. I still need to bond modules to modules and modules to rails. My racking supplier recommended and provided Dynobonds for module to module bonding (http://www.dynoraxx.com/dynobond), which I am planning to use, but open to not using. I would still need to create a connection to from the rails to the modules on each array, so I am thinking of placing a grounding lug on each of the two rails in each array, then using a bare copper EGC from the upper rail lug to the lower rail lug, then to a lug on the closest module in the array. Sound ok so far?

One problem is that the module installation manual from the manufacturer specifically says that Tyco 195431-1 ground clips should be used to ground modules. I thought I would get one of them for each array and put it on the first module in the array to connect to the grounding lug on the rails, but those grounding clips are only rated for 10 or 12 AWG solid copper. With only ten 1 amp micro inverters per array, a 10 or 12 AWG should provide adequate protection (and meets table 250.122 guidelines), but then there is the minimum 8 AWG EGC requirement that keeps popping up in my reading. This is a ground mount, so I suspect my AHJ would have a case for saying that protection from physical damage is required and maybe even require 6 AWB. Is there something I am missing that would allow me to use a 10 AWG instead of sizing up further and using different clips or lugs than specified by the module manufacturer? AHJ is coming to do an unofficial review this week, so I am trying to have my arguments lined up if I need them.

The next thing that is hanging me up is where do I take that EGC from there? What I plan now is that each array will have an NEMA 3R PVC junction box to transition from the SMA supplied AC field cable to 12-2 with ground UF-B. We will have PVC conduit running 18" into the ground, then run the two UF-B cables in a trench up to the Multigate. The Multigate is basically the combiner, so the 2-15 amp circuits combine and a 10-3 with ground is specified by SMA to run to AC disconnect. Still figuring out what size conductor to run from AC disconnect to meter. So, I think my bare copper EGC should go from my rails and connect to the green ground of the AC cable at the junction box, right?

From the junction boxes, do I need to run my EGCs all the way up to the house, or do I just connect them to a ground rod (or two) next to the arrays? I am confused about whether the green ground in the AC cable is the only one that has to run to the house or if both do? Since this is a separately metered system that is not connected to our house main panel at all, I don't think I am supposed to connect this to the house ground rods, but again, this grounding is where I am a bit lost. Maybe I still need to take the system to ground near the PV disconnect and meter?

If anyone is willing to address some of my confusion, I will be grateful. I have some more questions, but I suppose might be pushing it to add them to this very long post. Thanks.