If you thought that rooftop solar PV started a decade (or two) back, you could not be more wrong. In this fascinating story that encompasses over a century John Perlin takes you through the history of rooftop solar. You can read it here – How On-Grid Rooftop Solar PV Was Born. He has also written a book called Let it Shine: The 6,000-Year Story of Solar Energy. Do check it out.