I've picked up this nice solar panel and LiPo battery combo on Ebay from a suggestion from one of the guys on bicycle touring forum I hang out on. I got the MP-S23000 but there are many more on Ebay
The burb with it says it's 23000mAh/85Wh. Yeah right! 23Ah which I doubt! Maybe 2.3AH looking at the size of it. But it's handy. Has 5V out on a USB connector and either 12/16/19V out on a bayonet connector. Panel output is about 2½ Watts. Can power phone and Radio (or laptap) at the same time.
Biggest pain is charging it. It requires 15~20V DC. So just can't stick it on the battery while in the car. So I got some LM2577s on Ebay for a couple of dollars each. Now I can charge with any DC volts at hand and my 3 watt AC dynimo hub on the push bike, car battery, wall warts (even old VWs....).
Spashed out and got a 8.4Ah LiFePo and charger from HobbyKing. So have enough spare power for the time being.