The 5 Best Solar Backpacks. Instead of planning outings around the time and distance between power outlets, get a solar backpack to keep smartphones, tablets, laptops and music players charged up wherever the trail takes you. With a selection from our handy assortment of hiking, camping and commuter-friendly designs, you can do your bit for renewable energy and juice up those electronic devices while you're on the move. When users buy our independently chosen editorial picks, we may earn commissions to help fund the Review Parks.