As the owner of both of these:
>>1465696>>1465697to get real use out of solar you need lots of PV. The little folding array in OPs photo is sufficient for a single phone, and just barely. You want at least 7 watts, ideally 10 or more, because you aren't going to actually get that much out of it under realistic conditions.
This is why you need to oversize your PV for the application. Unless you're going to be innawoods for longer than 5 days and camping in the open (tree canopy will block sunlight) then you're better off just buying an especially huge capacity power bank. Because that's guaranteed power you already have stored before you even leave, and a bird in the hand is worth two in the bush.
That said if you're willing to shell out for large portable PV, it is pretty impressive and compelling to watch it quickly recharging your battery banks. Even understanding in an academic sense how it's working does not make it seem any less like magic.
