Did your Rv come with any house batteries? I would think it did otherwise none of your 12V items would work. If you don't boondock and you already have house batteries, then you don't really need to do anything. But you said you have nothing. Does that mean you bought a TT that does NOT have any batteries? Again, if you never boondock, go on the cheap, and get yourself 2 standard, deep cycle, sealed, group 27 batteries, connect them in parallel and call it a day. Just make sure you set the solar controller to the correct battery type, and you have an in line fuse. If you want to boondock, then you'll need to upgrade.