Solar-powered bicycle lights made in The Netherlands
The Pixio bike light has a built-in solar panel with a battery that charges up during sunny days when a bike is parked outside. Five days is enough for two years of biking with the lights on and the Pixio is already good to go for two years of biking with the lights on when you buy it. It comes in a range of colours, and a set of Pixios (back and front, as the law requires) will set you back 55 euro, but then those cheap bike lights and their batteries will run you a lot as well in the long run, never mind the stress they cause. It even has a locking mechanism so you can actually leave it on your bike, as long as your entire bike doesn’t get stolen or removed.
One obviously drawback is if you leave the lights on by mistake, but then that goes for battery-powered lights as well. Raise your hand if you’ve turned off someone else’s bike lights off as a courtesy. Parking your bike indoors like many people do won’t charge your light up, but then if you’re good to go for two years, you can cross that bridge when you get to it.