This bike has its own solar panel!
I was inspecting it and taking pictures of the "trunk" when the owner arrived, wondering what I was doing messing with his bike.
He explained that the solar panel lights up the DC powered LED christmas lights that were strung along the frame.
I think it's a very clever hack,and I'm a big fan of safety lighting that makes the shape of the bike instantly recognizable, but I wonder if it has some kind of giant capacitor or battery so that it works at night? I didn't think to ask him, unfortunately.