Well, I thought I was a solar convert until last week....
I've used solar over a generator for several years now and have been very happy with its ability (300W) to top up the batteries.
We spent this past week in a heavily wooded State Park - the weather was overcast all week. Needless to say I was watching my volt meter slowly decrease.
Luckily I did bring my generator, so used it for 1 hour each day to top up the batteries.
Last month we camped in a less wooded area with sunshine every day and the solar panels kept the batteries topped up.