Due to the cold weather in the evening during our visit to Disney World in Florida this January, we needed to take jackets, gloves and such with us each day. Due to a huge saturation of Virtual Munzees placed in Disney World, I had the need for a LOT of battery power for my iPhone 5.
In order to aid in both of these areas, I emptied out my work backpack and used it to haul my jacket, iPad and a few other miscellaneous items. Then, I used Velcro to attach a small solar charging battery pack to the backpack. While I can’t recommend that this particular solar charging battery pack, I can recommend the idea of a solar backpack if you need the extra power.
I’m also looking at actual production Solar backpacks (Google Shopping link) / Amazon Shopping link. I think they’re interesting but would not likely use a backpack enough to warrant owning one dedicated to solar. I’d probably prefer the flexibility to have the solar portion be more universal/portable.