Back in the day, 'solar' (for JUST the panels) cost $10-20 a Watt!
(Current cost ~$1-2 a watt)
The charge controllers have come down as well, while sometimes 'free' as a package deal with some panels, they can cost anywhere from $40-400.
However, the #1 problem with solar is not the cost it is with the availability of LIGHT - sunlight that is.
Forgetting for the moment that you will NEVER see the rated output of ANY solar panel you purchase, solar works best with the most unobstructed (no shade!) view of the sun as it moves across the sky from sun-up to sun-down.
So if your in the desert with no mountains or trees it will work much better than (for example) in a dense forest it won't work well or at all.
As an example, there are places that I park where my battery will be fully charged by 12:00 noon (if not by 2PM) and others where I get NO charge at all.
IMHO: Considering the cost of a Generator $400-2000 tossing ~$200 for some solar can be cost effective.
- Mark0.