Those are some fairly large panels. I suppose if you were running larger electronics, they would be needed.

I have two pieces of Brunton equipment, a solo 3.4 and a solaris usb. The solo 3.4 is nice to have for trips where you simply need something to bridge the distance between one plug-in to the next. It will do 4-5 small device charges before needing to be recharged itself. I tend to just use something like this on domestic tours.

Depending on the lighting conditions, the solaris will optimally charge the solo in a day, and may require 2-3 in poor conditions. This is certainly an adequate energy production rate to power a cell phone, mp3 player, 2xAA digital camera, PB Superflash and NR Minewt Mini USB. The Minewt is definitely the most power intensive device to charge, but my personal energy needs are met by this pairing.

On solar panels, you would want flexible amorphous ones like in the photos. Preferrably ones with some degree of water resistance. The crystalline panels like the Solio require fairly direct positioning towards the sun, and a lot of these small chargers will find themselves dead with a little water - a Solio I was given died after it was put out to charge, and my neighbors sprinkler fell on its side, giving the Solio a soak - not a real piece of resilience. Good flexible panels can be found which are nicely water resistant (or proof), and which aren't as needy for shadows, clouds or orientation.

I quite like n4zou's dynamo option as well. That could work quite nicely, as you would be able to skip having a battery powered light at night as well. I would personally prefer the panel as it will operate while not riding, which I do a lot of on tour - places to see, which is one of the nicest benefits, that you can use this system while not cycling and while doing completely different activities like backpacking if you want to. But for someone putting down a lot of miles on a bicycle, it would put out a lot of power, and could be less noticeable.