First off, I will confess that I’m too cheap to be an Apple guy, so I’ve never actually used an Iphone or Ipad. Instead, I buy cheap android devices, which I particularly like for hiking because if they become lost or damaged the financial consequences are minimal.
Having said that, my experience is that it’s been a great deal light, simpler and cheaper for me to buy a couple of spare batteries for my Android phone from an E-bay seller. The cheap, Chinese vendors sell them for $6-7 each and this enables me to simply bring my USB wall-charger with me and recharge all of the batteries while I’m in town. The batteries probably weigh about 30 grams each, so this is a very light way to extend the usage time for my smartphone.
I hiked the AZT this spring, so I know from personal experience that you will most certainly not lack sunshine if you elect to use a solar charger. However, do keep in mind that it’s a very dusty place and that can wreak havoc with some electronics (particularly cameras that have an optical zoom).
In any case, the AZT is an awesome hike, so enjoy!
Loup