[jyl]

I'm looking for a solar panel/charger that uses an easily portable panel (say, not more than 10 inches diagonal) and, in full sun, will deliver enough current to an iPhone to offset the drain of having the iPhone "on" and running GPS (Location Services) and a 3G connection.

In other words, suppose you start with your iPhone at 100% charge, then you leave the phone on when you are hiking or riding or whatever, and running your GPS mapping/training app (Garmin, etc) as well maintaining your cellular connection - but you aren't actually gabbing on the phone or surfing Pelican. And let's suppose you are doing this in full sun and the panel is appropriately positioned - on your hat or the top of your backpack or something.

The goal would be for the solar panel/charger to keep your iPhone at 100% indefinitely, even if you're in the backcountry for weeks or riding your bike across America.

Does anyone know of such a device, that actually works? And would any of our resident engineers be able to check, via back-of-envelope calculations, if such a device is possible?