That is my N900 summer travel setup (or if I travel in warm climates). I have to say I understand the pessimism, solar battery charging has it's drawbacks, especially since from my experience they tend to mess up the battery quite quickly. Also, I hope the Jolla has good charging software/communication... My first setup was a solar charger directly connected to the beast, but it usually just worsened the charge (software?) and confused the phone.
I still fully support the idea (and tech keeps improving). Remember, most of the population of the world live in warm/tropical climates, where this is useful all year long.
Good luck.