Hmm.. I see the issue..
The usb/solar/li-poly charger still appeals for its principle, because for days I can't carry a large solar panel, I could still charge by more conventional manners (but if I'm on an extended road trip, having a solar panel would be a great advantage).
The Adafruit USB/solar/li-poly charger linked to a Mintyboost (without the AA's, right?) can convert solar input to USB output, with a lithium battery in the middle.
The charger here on Amazon can use USB input to charge AA's. http://www.amazon.com/Rayovac-Everyday- ... aa+charger
Can the solar circuitry pass current directly to mintyboost, without the lithium battery? If so, it would seem like you could add a third circuit (or do a modification of mintyboost) to make the circuit go Solar --> usb <--> AA . Maybe a switch would could determine which direction the current flows between the usb and the AA (or I'd just reverse the direction of a diode), and I could only either recharge the AA's or discharge the AA's into my cell phone, but not both at the same time.. or something like this?
I'm not going to try too hard here, but it seems like there is (or could be) a way to make this work?
Or maybe just toss out my AA's and switch to lithium, eh?