Solar is great but you have to have a back up means of charging when the sun doesn't play well. That could be as simple as a pair of jumper cables or a generator. We don't take ours on shorter trips but I wouldn't hit the road without it. Leaving the batteries discharged for too long or take them down too far waiting for the sun may damage them.
To run a microwave off of battery even for a few minutes requires at least two batteries if not four, plus a inverter big enough to run it. It all cost money but then again quiet inverter generators are not free either. I would think a Champion 2000i inverter generator would be the least expensive way to go.