In reply to FesteringSore:
Powermonkey extreme.
Solar panel and battery pack. Can use both seperatly.
Downsides are its a tad expensive. And it's a touch button.
I would have preferred big chunky buttons.
Had mine for years, been with me all over the place. Solar panel works best in really sunny places. Temperamental in the UK. The bank usually held 6 full charges for a phone and 3 of an iPad.
Might be worth a look.