From what I have read you need direct sunlight for optimum power generation.
Solar panels and shade simply don't mix. While some panels claim to be shade tolerant, you will lose substantial charging power even if only a partial area of the panels is affected by shade. If one quarter of the panel cell area is shaded, the juice being cranked out will be virtually nil.
Check out this link where I got the quote:
http://www.greenlivingtips.com/articles/...ar-panel-basics.html
Maybe you could mount the panel on top of a pine tree or on a pole?