I have a 3kw inverter with a built in transfer switch. My main incoming power cable goes to a 8 breaker sub panel, 2 for the ac's, 2 for the Inverter / Charger (I/C), 1 for the electric water heater, 1 for the factory 100 amp converter. The other 2 are spare at the moment, 1 will be a garage AC at some point.
The 2 going to the I/C charges at up to 150 amps, as well as powers the factory main breaker panel. This means when I have either shore power or generator power I have everything working, running off batteries I loose both AC's and the electric water heater - everything else works as normal. I am installing a 15 amp transfer switch so I can run the main AC off the inverter, for now using a Costco 2000 generator to top off the batteries (55 amp charger about maxes it out) but soon solar..