ABSTRACT
Becquerel [1] ¢rst discovered that sunlight can be converted directly into electricity in 1839, when he observed the photogalvanic e«ect. Aµer more than a century of theoretical work, the ¢rst solar cell was not developed until 1954, by Chapin, Fuller, and Pearson, when suªciently pure semiconductor material had become available. It had an eªciency of 6%. Only 4 years later, the ¢rst solar cells were used on the Vanguard I orbiting satellite.
