A 6.5W Folding Solar charges my phone via a 12v - usb adapter.

A Mili Power Crystal Portable Emergency Charger Pack can also be charged by the same USB output.

My starting setup involved running the panels output through a 12v usb adapter and into the Mili battery, which was connected to my phone. The idea being that once the phone was charged the Mili would then soak up the excess acting like a resevoir tank, which would charge the phone in low light.
In reality a highly optimistic configuration as the USB adapter needed the full 12v to run and therefore was pretty useless. A work around was acheived, allowing some charge, by connecting the Mili directly to the panel and on the odd occasion more than 5 volts were produced charging occured.
Power was on the whole rare, I was not able to use the phones mapping or GPS and infrequently had enough to send a text or update my position.
I will find a solution to this problem before my next trip.