I highly recommend going on Amazon.com and checking out the jackery bar. They come in different sizes based on how many recharges you want. The smallest will recharge a standard iphone from 0% to 100% approximately 1.5 times. I have the smallest one and another larger one I keep in my truck that will recharge my Samsung S3 4 times! It recharges on a USB/microUSB cord (provided) and i got them both dirt cheap. The big one weighs around 9oz so it's not the lightest option, but the smaller ones are slightly larger than a sharpie marker.

Most of my hiking is in the woods with not a whole lot of direct sunlight so the solar thing doesn't work for me...

good luck!