1839 - Edmond Becquerel observes the photovoltaic effect via an electrode in a conductive solution exposed to light. 1873 - Willoughby Smith finds that selenium shows photoconductivity. 1874 - James Clerk Maxwell writes to fellow mathematician Peter Tait of his observation that light affects the conductivity of. In the 19th century, it was observed that the sunlight striking certain materials generates detectable electric current – the. This discovery laid the foundation for. Solar cells have gone on to be used in. • 1932 - Audobert and Stora discover the photovoltaic effect in (CdSe), a photovoltaic material still used today.• 1935 - Anthony H. Lamb receives patent US2000642, "Photoelectric device." • 1946 - files patent US2402662, "Light. • 1980 - The at University of Delaware develops the first exceeding 10% efficiency using Cu2S/CdS technology.• 1981 - is founded by in. 2020• of have increased from 3.8% in 2009 to 25.2% in 2020 in single-junction architectures, and, in silicon-based tandem cells, to 29.1%, exceeding the maximum efficiency. • 1901 - observes the variation in electron energy with light frequency.• 1904 - makes a semiconductor-junction solar cell ( and ).• 1904 - • 1960 - Hoffman Electronics creates a 14% efficient solar cell.• 1961 - "Solar Energy in the Developing World" conference is held by the.• 1962 - The communications satellite is powered by solar cells. • 2003 - George Bush has a 9 kW PV system and a solar thermal systems installed on grounds keeping building at the White House • 2004 - California Governor Arnold Schwarzenegger proposed Solar Roofs Initiative for one million solar roofs in.