transfer switch and wiring

[KODAJACK]

On a truck camper.....
I am installing a 3000 watt inverter charger, 400 watt solar panel, and 300 AH lithium battery. The exisiting transfer switch has the onan 2500 in the connection. I am getti ng rid of the generator because i wont need it with solar and the alternator charging. I will be keeping the 30 amp shore power wiring for emergency generator if needed. I can wire the 30 amp cord to the into the inverter/converter so it will go to the inv/conv instead of the tranfer switch. I will ber keeping the origianl microwave and adding a induction cooktop.
My questions......finally....
1. what triplex wire size do i need for 3000 watt inverter? 8/3?
2. Is the 15 amp breaker box enough for the truck camper AC system? Should i have 15 amp breakers for the main AC line and one separate for the microwave?
3. Can I use the existing transfer switch or does the inverter/converter take over and I can delete the existing transfer switch?

Thanks for your help. Let the Experience and knowedge poor in.....!

 

[time2roll]

1. #10 is perfectly fine for up to 3600 watts, 30 amps, 30 amp breaker.

2. 15 amp is probably fine unless it is a full size 13.5 or 15K BTU. Many TC are 9K BTU A/C units. The main cord is probably 30 amp feeding into the breaker panel. Or is the main AC line the general convenience outlets where 15 amp is fine? Yes generally a separate branch circuit is used for the microwave. 15 amp for a smaller unit, 20 amp for a full size unit. 20 amp breaker needs #12 wire. 15 amp breaker #14 wire is fine.

3. Assuming the inverter/charger has a transfer switch then yes it is best to remove the existing transfer switch when you remove the generator.