I had to answer this question for myself in order to figure a way to
keep 8 golf cart batteries charged down at our duck camp. Depending
on how many watts you need, I don't think you can beat Northern tool.
The 15 watt panel is the best deal in dollars per watt for a new
panel. You'll also need the charger controller; they sell that as
well.

http://www.northerntool.com/webapp/w...3174_200263174

Ed.