In reply to Simon Holden (LCandCC):
I'm not an expert, but if you want something that'll charge up in the day, and then charge your phone at night, then that involves a battery (and the weight of it, that earlier on you seemed to be trying to avoid?).
We've got a power monkey extreme - you can charge the battery from solar panel, or from electric socket. It'll do something like an iPad once, or smartphone several times. Charging off the solar panel takes all day in bright sunshine, though - great for summer trips to sunny places, but not necessarily too useful in the UK.
But if you leave with the battery fully charged, it'll do you pretty well. Particularly if you don't have two children who you want to entertain whilst you get some climbing done!