ello
How about an alternative.
Any cranck phone charger that as mini usb or micro usb output (or any other proprietary connection), is able to charge an eBook reader to the full.
In my country, nowadays, I can get a led flash light cranck powered that can charge mini/micro/other connections devices for less then 8 euros, and the best is… no dependence on the availability of sun [I have nothing against solar power, for the (completely) contrary!]
(this is just an example:
http://www.amazon.com/SOS-Charger-Ha.../dp/B002WRKZZ4)
Best regards,