Don't bother with solar. they charge far too slowly to be of much good, unless you can measure the panel in square feet. But if you do go solar, then its an easy matter of charging a USB pack as they tend to not mind variable power as much, where phones do not like it at all.
As far as the battery pack, there are a lot of good ones, and a lot of not good ones. There can be a big difference between the efficiency of the circuits, so a cheap 5000mah pack might be as good as a 2500mah expensive one. I have two, a 5000 for everyday stuff, gets me about two full charges of my phone, and an 11400 which is for when I'm away from home for a few days, and power might be scarce.
Charge speed depends on the unit, both of mine are two port units, one can do 0.5 amp (computer USB) or 1 amp (normal wall wart charger) the other can do 1 amp or 2.1 amp (Ipad charger, very fast) But you pay for getting faster charge, and it is less efficient, depending on your phone, some can take 2.1, some cannot. the good chargers will sync with the phone's charge circuit and only give the power it can take. 2.1a will do a phone battery in something like an hour. give or take.
as far as re-charge, my big one will take most of a day from empty off my big usb wall charger.
