I had never heard about this, besides from Catweazle of course who, as 'we all know', asked his 'master' how he had put the sun in a bottle 🤣

Still baffled by the fact I had no idea: adding bleech (against algae) to a bottle filled with water, plug it into a galvanised steel frame during sunlit hours, and you have light in the evening. And it's even quite bright!
This all started more than 10 years ago and I had no idea.

https://literoflight.org/