I am not sure why you would want to go the way of having a solar panel to recharge your battery system. The current range of LED style lights give pretty remarkable endurance on battery life.
I have a pricton tec headlamp which gives a "claimed" 70 hours on max output from 4 AA batteries. A gel cel battery and a spare if you think you need it would probably keep you going for a very long time.
But then I don't know what you have in mind??

Cheers Bill