I am a pretty big proponent of having 12v electrical power with me. I am very unconventional when it comes to this, however, so my method certainly is not for everyone.
I use a 12v battery and traditional 12v plug for a USB converter. That is what I charge my phone and GPS off of. I run a Garmin Edge 1000.
For my day rides in the past a 9Ah SLA battery has done an adequate job.
I have a set of solar panels from PowerFilm that I put together for charging when I'm stopped. Any extra photons I can scrape to put in the battery the better.
I don't worry about charge controllers. I just monitor the voltage of the battery manually. I have never run in to a situation where I was at risk of over-charging. Just floating the battery voltage in full sun is about the most I expect, but I keep an eye on it regardless.
I am replacing the 9Ah SLA with a 12Ah Lithium Iron Phosphate battery - bigger case, more capacity, but substantially lighter weight than the 9Ah SLA. The usage and charging is going to be identical to what I described above.