5 VOLTS (not watts) at 2 amps. If you're carrying a panel that can reliably deliver that, it's going to be big. What you probably want if you must charge strictly from solar is a battery that will trickle from the solar and then dump power into your devices all at once. However, I really don't think you'll be able to keep all that stuff charged even if you stop for an hour or two to charge things at mid-day when solar output would be at its highest.

If you have ready access to AC power, I VERY HIGHLY RECOMMEND this thing:

AnkerŪ 40W 5-Port Family-Sized Desktop USB Charger

It's deck of cards size, has 5 outlets, can put out 40 watts, and will just automatically detect what kind of device you plug into it and reconfigure the port. You can plug in an Android phone, an iPad, any number of things and you'll just automatically get ports configured optimally for that device. I just got one and it's fantastic. I'm not screwing with anything else anymore, especially for travel. Just being able to plug everything in at once without worrying about compatibility is great.