There are a few small solar panels available out there specifically for game cams. I have tried on in the past but it wasn't worth a poop. I will admit that it was an older cam. Maybe with something like a new Bushnell Trophy a panel might work because I think they use less batt power up. (I have gotten amazing battery life from the Bushnell)

Here's a link for your reference:

http://www.cabelas.com/product/Moult...s#BVRRWidgetID