I use two cheap solar panels (A5-paper size, folding ones) on bike trips, one without a battery and one with. I have both installed on my bike all day, with my GPS device plugged in to one of them all the time. I travel on roads and in a particular direction, so I can adjust them every two hours or so to face the sun. This keeps the battery on a respectable level, but the real charge comes when I stop for an hour to make something to eat. I direct the panels to the sunlight, and after one hour, my GPS is full, phone is recharged, and the camera (pocket-size automatic one) also gets some. In the evening I plug the camera to the second charger. Never had energy problems, but I am aware that this setup is very sensitive to unexpected sun outages.
Sorry for lack of specs, the new bike season is starting soon, and forgot everything from the last summer. :-) Just my 0,02€.