You're in luck—there are several excellent solar chargers on the market. And with the number of sophisticated electronic devices people are now carrying, it's no wonder that solar chargers are becoming more popular.
For lightweight travel, check out the Goal Zero Guide 10 Plus Adventure Kit ($160). It comes with four rechargeable AA batteries (with an adapter, it'll charge AAAs, too), and will also connect to any device that can carge with a USB cord. In bright sun, the AA pack fills up in three or four hours. Plus, it’s compact and light at two pounds.
I also like the Solio Bolt ($70). It comes with panels that fold out, and, like the Guide 10, it charges devices with a USB cable. Charging an iPhone takes three to four hours. One nice feature is the Bolt's internal battery, which can re-charge up to two devices when at full power. Even better, that internal battery can be charged with the sun or plugged into an outlet, giving it great versatility.
And take a look Brunton's incredibly small, lightweight Solaris 6 ($240). When folded it fits into a pocket and weighs only 7 ounces, and Brunton bills its copper indium gallium diselenide panels as the most efficient on the market (and it’s fun to say “copper indium gallium diselenide”). The Solaris will charge AA or AAA batteries and nearly any electronic device you can find. It can even trickle-charge a car battery, and it's possible to link up to three Solaris 6s for even more charging power.