Solar Cells produce electricity from sunlight.
In 1873 and 1874, scientists noticed that selenium reacted with light to produce electricity. During the 1870s William Adams and Richard Day proved that light plus selenium generated current. Eventually, famous German scientist Werner von Siemens (founder of Siemens) was excited about the possibility of solar cells in the late 1800s. Indeed, in 1905, Einstein explained what made solar cells work, “light quanta” – that we now call photons.
Subsequently, by the early 1930s, scientists were enamored with solar cells: “…in the not distant future, huge plants will employ thousands of these plates to transform sunlight into electric power…that can compete with hydroelectric and steam-driven generators in running factories and lighting homes” wrote German scientist Bruno Lange in 1931.
However, as the cells proved inefficient, interest waned. By 1949, scientists had all but given up hope on a reasonably efficient solar cell.
Eventually, five years later, scientists Calvin Fuller and Gerald Pearson of Bell Labs were working with silicon to create transistors. They noticed that silicon could generate electricity.
In a different area, scientist Daryl Chapin was tasked with the remote generation of electricity. He started to experiment with selenium but faced the same problem earlier scientists had, efficiency of just 0.5 percent. Pearson told Fuller he was wasting his time with selenium and to try silicon, which ran at 2.3 percent efficiency, much higher.
Bell labs continued working on solar cells and, on Apr. 25, 1954, displayed a 21-inch Ferris wheel that ran on a solar-powered battery. The press loved the concept: unlimited, free energy from the sun.
Subsequently, solar cells have since fared better and worse, becoming popular in the 1970s only to disappear again. Eventually, they reemerged in the 2000s as a viable source of electricity.
As of 2018, solar cells have efficiency as high as 22.5%. As efficiency increases and price decreases, solar is becoming one of the least expensive options to generate electricity; only wind energy costs less.