I have 450 watts on the roof of my TT. I have two 6 volt battery in series. Installed an 3000watt inverter in the TT that I plug what ever into.
I have never been at a loss for 12 volt power day or night. My charge controller is a blue sky energy 3000I
Blue Sky Energy Inc. | Solar Boost 3000i
I picked this controller because I can adjust the charge voltage and float volts as here in Colorado normal float volts will boil the water out of the batts fast. The controller also equalizes the batts once a month. I store next to my house. When I cover the TT I plug into 200 watts I have on my roof. Keeps my batts maintained 24/07 x 365 days.
Don't mean to ramble just want to input the controller is important as batts are big$$
For them hot days I have 2-2000 Honda's to run the ac.