For what it's worth: I just purchased a 12v/5.5watt solar panel to experiment with charging my iPad. It's about 12inches by 14inches. I hooked it up through a car lighter socket and a USB charger, which works just fine when I use it in my car.
The iPad shows the charging symbol when it is plugged in.
Result: On a bright sunny day, with me moving the panel every hour to keep it pointed at the sun, I got about 7% of a full charge in 4 hours. Not so great...
The iPad shows the charging symbol when it is plugged in.
Result: On a bright sunny day, with me moving the panel every hour to keep it pointed at the sun, I got about 7% of a full charge in 4 hours. Not so great...