Does your phone use a USB port to charge (or can be adapted)? How handy are you at soldering? http://www.ladyada.net/make/mintyboost/ AA batteries are relatively cheap, have excellent shelf life, don't (usually) upset airport security and customs inspectors, and are ubiquitous world-wide. The Mintyboost can be built/modded to work with larger C and D cells. Unfortunately, I can't yet comment 1st-hand on how easy it is to build and use, as my kit is still in the plastic bag (it's on the to do list). The instructions on line are excellent and the local hacker-space community uses the kit as their "learn to solder and build something electronic" starter project. RS and the usual on-line sources probably sell something similar. For solar, your choice is cheap and takes forever to charge your device (assuming it can give it a full charge) or expensive and works acceptably (as long as there is sun).

Figure out how many day's use you need to get from your electronics, how that compares to their battery life, how much extra stuff you want to carry to keep the electronics working and what it's worth in $$ and peace of mind to you (and whomever you want to stay in touch with while you're away). Have a back-up plan for when (not if) they fail or just aren't available to you.