Not heavy use.
If we use an inverter, it will only be for television and DVD player. We do like to boondock a lot, but will change to LED lighting.
I agree that the pricing is very high, but I am unsure of self-installation. I am less concerned about sealing the holes I make in the roof as being sure I have a secure attachment. I would hate for the wind to rip them off the roof at 60mph on the interstate.
As far as the lithium battery option, with all of the hoopla about lithium batteries catching fire, I am leery of them.