For on-the-go charging of a phone or other small device, wouldn't one of the power banks, pre-charged prior to your trip, be more practical? I can recharge my phone (admittedly, a small flip phone) a bazillion times off of one power bank charge.

I've recharged my fliphone several times, my Kindle Fire tablet a couple of times, and my MP3 player once over the last 6 months from a single power bank, and the power bank is still showing 3/4 full (of course that could actually mean 1 second over 1/2 full, since there are 4 LEDs to indicate charge status - 3 of those are currently lit on mine). My power bank is a smallish one, only 12000 mAh and 8.5 oz.

I can see how solar panels would be very handy for extended trips out in the middle of nowhere though. Or if you have a whole lot of power hungry devices that you use frequently (but then, you'd probably spend all your time futzing around with the solar panels and your electronics may become the focus of your trip). And panels are quite a bit more bulky and heavier than a power bank. I would guess they might be more fragile too, but I don't know.

I can see solar panels being a good fallback (backup) if you can handle their space requirements and weight. But unless I'm missing something here, I don't see them as being a very good choice for primary charging.