3 inverter AC setup, is this safe?


Solar Addict
Dec 18, 2022
I'll have 2 5000w Victron Quattro inverters setup in split phase 240V (lets call Red and Black), then will have a 3rd 5000w Victron Quattro inverter (lets call Blue) as a secondary system for some redundancy. The plan is to have the 240V inverters power 3/4 of the coach then the other 1/4 will be on the 3rd inverter, allowing me to use different outlets incase any issues as both systems are completely separate with separate battery banks. The 240V goes into the left panel Red/Black then through the bottom to the right panel BUT then only the Black inverter powering half the breakers. I'll then have the 3rd inverter (blue) coming from the top on the right panel powering that half of the breakers. I know it wont be the far right side and every other one on the right panel. The 240V is 4 gauge wiring for red/black inverters and the blue inverter will be 6 gauge.

The problem is the ground and neutrals will all be connected together which should be ok. The main reasoning for this instead of a subpanel is I can easily swap breakers around incase of an issue.

I'll then have the red inverter using a 30amp breaker on the left panel to send into input2 of the blue inverter. I can then use logic to control when I want to switch the blue inverter to passthru or invert. So if I connect the black/red inverter to 50amp shore I can use all the power from shore and charge both banks off the single cable OR I'll have a shore cable for the blue inverter to IN1 and can connect it there so it'll have 1 leg of 50amp shore while the black/red has both legs and I could get 18kw power coming in. My 20kw genny will be on in2 of the black/red.

Wired up and all is working great. Now I just need to think of some logic and how I want to have 1 system tell the other to charge. Also figure out which relays and i/o to use. Looks like the Quattros have a bunch of ports and options as does the Cerbo's.

Also need to figure out which outlets and devices go on which system. 48V gets 1800w solar but 12V gets 2000w+ of alternator power when driving. Lights are on 12v as is wifi but maybe I need to move wifi to 48V since POE is 48-52V.

Something like if 48V batteries are at 80% SoC then turn on enable in2 on 12V. But also maybe if connected to 50amp shore enable in2 on 12V so it can use all 50amps and charge both banks at same time.

Any tips or ideas?
Incase anyone's following along I went camping for the weekend and this worked out perfectly. Was able to run everything and keep cool in a hot sunny weekend without any electrical issues..... Well except I had a cheap 12v to 48v buck inverter for my POE and starlink which I found out somehow fried as it was only outputting 12V. This fried my starlink dish and of course we didn't have cell service at the CG so relied on CG wifi which was horrible :(

Only 1 of my 48V inverters is working so I had only 1 leg of 50a to charge. We left the house for a 1.5 hour drive to checkout saturday morning's auction and the alternator was charging the 12V while we were using the front AC (only one on 12v) which provided plenty of power, I actually need to turn down my alt as I think its only 2ga wire running 40ft. RV sat parked for an hour or 2 while we checked out the auction then we got supplies then headed to the CG. I have the 6 ACs setup so it turns on different ACs as the temps rise in the coach except the front AC which is only one on 12V which we manually control. We travel with dogs so keep the coach cool and we pulled off most of the blinds as we're working on window tinting (lot harder than it looks to diy) and replacing with motorized blinds. Saturday at 5am we loaded up and headed to the auction, chilled in the parking lot until it started around 9 then we left around 2. Scored a 50a 100ft RV extension cord for $75 along with other goodies :) headed back to the CG then left Sunday around 11am. The CG actually had 2 pedestals in our spot so if I finished up my 12V wiring I could have ran both inverters to shore.

I manually changed the 12V inverter to charge from the 48V inverter using 120v on a 30amp breaker. It seems the new update allows my Quattro to go below 13.4a and I was able to set it to 10a and even 8a which was great. In total for the weekend 8/18 10am-8/20 12pm) 13.6kWh from solar, 85.8kWh from shore. 96.3 kWh total consumption on 48V of which 22.8kWh was passed to my 12V which consumed 23.2kWh (assuming the .4kWh was from alt).

Hopefully will have my other 48V inverter fixed soon so I'll have 240V in the coach, also will have my 12V 50a shore plug wired up so if needed I can charge from both giving me like 18kWh of input power :)