I've bought two solar chargers in the past, and neither worked on my iPhone, although they did work on other phones.  The way I understand it, the 300-500mA output of this and other compact solar devices just doesn't cut the mustard with the iPhones, which have a current requirement above standard USB specs.  If I'm wrong, and/or you know of a pocket-sized solar charger that'll do the trick, do let me know.