18kpv install - questions about 2 200 amp panels tied to 1 meter main

[jonjon09]

Hey all, I have been patiently waiting for my electrician to install my 200 amp fused disconnect so that I can get my 18k and 2 powerpros going. Very excited, already did the firmware update while waiting (got delivered over a month ago after already waiting a few months for the delivery to begin with, my patience is being tested lol).

I have a few questions before he (hopefully) comes by next week to install. I have 2 200 amp main panels running off 2 separate 4/0 lines from the meter main outside. No existing disconnect for those. I also have existing solar panels with micro-inverters and existing 60A disconnect so I plan to re-route that line into the GEN terminal on the 18k instead of being tapped into the 4/0 line at the meter main. See rough diagram below that I drew for my electrician months ago.

Questions:
1. Should I just connect the CT clamps to the line for the main panel that will be backed up since I don't think I can manage to get the clamp around both 4/0 wires and have no plans to use the 18k to tie into the 2nd garage 200 amp panel? I saw the other thread that mentioned monitoring both for another user but I don't see how I could manage that? The garage panel is high non-essential loads (tankless water heater, Tesla wall charger, irrigation pump)
2. My electrician seems convinced that I also need a disconnect switch (non-fused) for the garage 200 amp panel despite it not being tied to the 18k or any other solar/batteries. Is that a NEC requirement? Drives up my cost but if needed I understand for safety reasons... Not much room on the outside wall for it both.
3. Is there a problem with the way I am running the wiring as shown in the rough diagram to the main 200 amp panel? Not really using any kind of tap as mentioned in the EG4 manual but it seems fine based on the Sol-Ark wiring diagram... Running new 4/0 wires from the meter main -> 200 amp fused disconnect -> GRID terminals on 18k and relocating the existing 4/0 wire (that is currently tying the meter main to the main 200 amp panel) directly to the LOAD terminals in the 18k.

TYIA.

 

[goldserve]

Instead of fused disconnect, would a fused manual transfer switch to allow you to bypass the hybrid inverter incase it needs servicing?

 

[jonjon09]

Instead of fused disconnect, would a fused manual transfer switch to allow you to bypass the hybrid inverter incase it needs servicing?

I thought about a manual transfer switch based on the 18k diagrams but between the added cost and the limited wall space, I decided against it. I went with the SIEMENS GF224NR instead.
Assuming there is no issue with my wiring (see question #3) - I assume I should be able to just temporarily splice the 4/0 GRID and LOAD wires if the 18k ever needs servicing (another benefit of having the 200 amp disconnect).

 

[wheisenburg]

Your proposed design looks fine to me. Hopefully you already got this installed.

One thing to be aware of is that if you ever decide you want to add a generator to your system, you will need to make sure that the generator can never run at the same time as the grid tied PV. Can you let us know how this worked out?

 

[jonjon09]

Your proposed design looks fine to me. Hopefully you already got this installed.

One thing to be aware of is that if you ever decide you want to add a generator to your system, you will need to make sure that the generator can never run at the same time as the grid tied PV. Can you let us know how this worked out?

Thank you for the response! Yes I did get my electrician out here and got it all installed. We mostly stuck to that diagram with the exception (to the recommendation of my electrician) that we actually tied both 200 amp panels to the fused disconnect to avoid needing 2 separate disconnects (to be up to code according to him).
Only the main 200 panel is tied to the 18kpv however but doing this actually ends up being great because the batteries and solar can still power both panels while the grid is ON but will only power the main panel when the grid is OFF.
The only downside of this approach is if I were to ever use more than 200 amps at the same time, the fuses would blow but I do have some extra fuses just in case and it is quite unlikely to happen based on our usage.

And thanks for the heads up, I have no plans to add a generator but definitely did notice that as a big no-no in reading through the manual.
Still trying to figure out the different settings, have it configured as purely battery backup for now but I plan on having it power my loads a lot more often once my utility company switches us over to Time-of-use in the next year.

 

[wheisenburg]

And thanks for the heads up, I have no plans to add a generator but definitely did notice that as a big no-no in reading through the manual.
Still trying to figure out the different settings, have it configured as purely battery backup for now but I plan on having it power my loads a lot more often once my utility company switches us over to Time-of-use in the next year.

At the time I built my system, I was planning to have a generator as a backup during a more extended outage. I installed an 80 amp 4 pole contactor with 2 NO and 2 NC contacts. This thing is pretty huge, but I sized it in case I ever added a 4th string of PV. It uses the voltage from the generator to switch the contacts. So basically it goes inline on the incoming side of both the PV and the generator. The PV is on the NC contacts and the Gen is on the NO contacts. So when the contactor is not powered on, the current from the PV just flows through the Normally Closed contacts. When Gen voltage is sensed it opens the PV circuit and closes the Gen circuit. Note that for me I needed a 4 Pole device because it requires more than just combining the two sources. The PV and Gen go to different destinations, so I needed a 4 pole device.

Probably a better way to do this now would be to just use a chargeverter. Among the benefits are you can get by with a smaller generator since it does not have to power all the house loads along with charging the batteries. Also, if the Gen has dirty power, it only goes into DC current for the battery. It doesn't go into your entire house. Finally no transfer switches or lockout is needed as long as you just pump charge current into the batteries.

 

[dougbert]

Probably a better way to do this now would be to just use a chargeverter. Among the benefits are you can get by with a smaller generator since it does not have to power all the house loads along with charging the batteries. Also, if the Gen has dirty power, it only goes into DC current for the battery. It doesn't go into your entire house. Finally no transfer switches or lockout is needed as long as you just pump charge current into the batteries.

I love the chargeverter model of grid charging (1, 2 or more of them)
my inverter can just be an inverter all the time