Ok, so I am kind of stumped. It seems I need an anti-islanding device. I need to have the full 200 amp grid service when the house is built. Once I move in I plan to do all the solar install and minimize the grid usage once that is up. Seems like any GTI inverter has way to small a capacity so or is intended to work with panels from the start. None that I look up have high pass-through current.
So what is a UL listed solution for that? I was hoping for an off the shelf device to just have installed between the grid entrance and the main load center so I could drop power later and do all the inverter and power work myself.
Can I just use an auto transfer switch with time delay for the job and leave the generator leg disconnected? Route the load leg down to an empty breaker panel then connect the main load center with all breakers in it off the bottom lugs. Then later snap
breakers Into the empty panel to connect a quad of LF DC coupled inverters into it? Room for more is needed?
Something like this "Eaton BR 200A 4-Space 8-Circuit Main Breaker Load Center" with 4 x 50amp 2-pole breakers for the feed through?
If I ever wanted to go completly off grid I could just turn the transfer switch.
PV interconnection always gets interesting because of the NEC "rules" on interconnection. I will list a quick overview of how you are allowed to interconnect, as there are some specifics to keep in mind.
If you want to just pop a breaker into a main panel the rules are as follows:
- Either- all bus breakers in the panel must total less than the busbar rating of the panel
- Or- Pv breaker must be at opposite end of busbar from main and total of main breaker + PV breaker must be no more than busbar rating of panel x 120%. (For example- 200A rated panel x 1.2 = 240A total. So- 200A main + max 40A Pv breaker or 175A main + max 65A PV breaker.)
Your "Eaton BR 200A 4-Space 8-Circuit Main Breaker Load Center" would work as the main panel, however that would limit you to just those 4x 50A breakers (I assume you are talking about 1 pole for feeding Victron 120V inverters.). So then you would essentially be limited to 100A of total draw. And you couldn't legally use that panel installed as a sub panel off a separate main panel, because then your 200A breaker feeding this sub panel would be the interconnection point, and would not be legally allowed, if you look at the requirements that I listed above.
The other option is a line side tap. Some power companies don't like and/or allow a line side tap. A line side tap will be by far your best option for what you said you want to do. Basically what it is, is a separate service specifically for your solar. The wires feeding that service get connected to the wires between your meter and your main breaker in the service entrance panel. Then you go directly to an outdoor fused disconnect that gets grounded and bonded as a main service disconnect, and from there you could go to a panel that is specifically for you solar system.
If the power company does not want a line side tap, you could always just say you want a 400A service, and have 2 separate 200A outdoor fused disconnect for you service entrance. Then one would be your grid direct loads and the second one would be your PV disconnect that is lockable and meets NEC requirements. From the PV disconnect you would go directly to that Eaton panle that you mentioned, and because it would be full with those 4x 1 pole 50A breakers, it would be a legal interconnection. Those would feed through the inverters, then on the load side you would have critical loads panel, and once again, you will need to ensure that the panel will not be overloaded between the mains from those inverters, and the GT inverter breaker. So using a 200A main lug panel and again 4x 1 pole 50A breakers for the mains, you would have (200Ax 120%) 240A - 100A (those 4x 1 pole 50A) = 140A of headroom for GT inverter!
GT inverter breaker is sized as follows. Max amps rated x 1.25 == round up to nearest higher breaker size. For example, a Fronius 8.2 is rated 34.2A, so 34.2 x 120% = 41.05A. Round that up to 50A and that is your breaker size.
Keep in mind that when AC coupling to almost any battery based inverter, you need to keep a 1:1 ratio in rated wattage between GT vs battery inverter. So if you have 4x Victron 48/5000 multiplus II then your are limited to 20,000 watts total of GT inverter. So you could go up to, say, 2x Fronius Primo 10.0.
As far as an anti-islanding device goes, I believe that in the US when the Victrons are not actually the ones pushing the power out to grid (your GT inverter would be the one doing that.) you probably don't need a special anti-islanding device. Now do your research on this, as I haven't set up Victrons in an AC coupled Grid-tied scenario! At home I'm AC coupled, but off-grid.
I believe the Victrons disconnect quick enough to be legal, and during a power outage/grid disconnect scenario, the GT inverter would actually shut down for 5 minutes due to seeing the power fluctuate during disconnect.
I do know for sure though, that an inverter like the Schneider XW Pro would definitely not need any additional anti-islanding device.
Hopefully this helps, and doesn't make it confusing. It is always interesting figuring out the best (and NEC code compliant) way to interconnect! But I have found that generally speaking, if the PV system will need more than a 40A breaker, then a line side tap is almost always the only viable option after looking at all angles!