Storage is the primary reason, but since I am installing solar, why not add a little more capacity? I am not looking for portable panels, The idea would be to mount something on the roof and wire it in with a charge controller. As soon as I leave the CG the solar kicks in and charges the batteries while I'm going down the road. I am not looking to cover all of my boondocking use with solar, but any capacity that helps reduce generator run time is a bonus.
Right now I leave the TT plugged in 24/7 at home and it keeps the batteries on trickle charge so they don't freeze in the winter. Ideally would like to do the same with solar, provide enough energy to keep the batteries onboard through the winter. We don't get much snow down here (except for this winter LOL)so worst case the panel would be offline for a day or two until the snow melts.