Non-silicon cells are older, but still fall in the 20th century[1]. Maybe copper oxide cells are older still? [1] https://solar.lowtechmagazine.com/2021/10/how

Non-silicon cells are older, but still fall in the 20th century[1]. Maybe copper oxide cells are older still? [1] https://solar.lowtechmagazine.com/2021/10/how-to-build-a-low-tech-solar-panel.html https://solar.lowtechmagazine.com/2021/10/how-to-build-a-low...