I am using plan on using map my ride app to help me navigate my rides. I plan on using an I-phone mount to my handle bars. As I am sure many of you are aware this can drain the battery quick on a phone. I am looking at getting a solar panel that can mount on my rear rack. or maybe on a luggage carrier of my front handle bars. Either way I had envisioned the cord from the solar panel going to the phone and charging it. However, as I have begun to look at these, it has appears that typically the solar panel charges batteries and then you plug in your phone later in the the charged batteries. Are any of you aware any solar panels that directly charge I-phones. Also, is there a way to calculate how much juice (wats/amps; not sure of the proper terminology) a phone that is navigating uses, and subsequently direct what solar panels I should be looking for.