In the 19th century, it was observed that the sunlight striking certain materials generates detectable electric current – the photoelectric effect. This discovery laid the foundation for solar cells. Solar cells have gone on to be used in many applications. They have historically been used in situations where electrical power from the grid was unavailable. As the invention was brought out it made solar cells as a prominent utilization for power generation for satellites. Satellites orbit the Earth, thus making solar cells a prominent source for power generation through the sunlight falling on them. Solar cells are commonly used in satellites in today's times. 1800s 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 selenium. 1877 - William Grylls Adams and Richard Evans Day observed the photovoltaic effect in solidified selenium, and published a paper on the selenium cell. 'The action of light on selenium,' in "Proceedings of the Royal Society, A25, 113. 1883 - Charles Fritts develops a solar cell using selenium on a thin layer of gold to form a device giving less than 1% efficiency. 1887 - Heinrich Hertz investigates ultraviolet light photoconductivity and discovers the photoelectric effect 1887 - James Moser reports dye sensitized photoelectrochemical cell. 1888 - Edward Weston receives patent US389124, "Solar cell," and US389125, "Solar cell." 1888–91 - Aleksandr Stoletov creates the first solar cell based on the outer photoelectric effect 1894 - Melvin Severy receives patent US527377, "Solar cell," and US527379, "Solar cell." 1897 - Harry Reagan receives patent US588177, "Solar cell." 1899 - Weston Bowser receives patent US598177, "Solar storage." 1900–1929 1901 - Philipp von Lenard observes the variation in electron energy with light frequency. 1904 - Wilhelm Hallwachs makes a semiconductor-junction solar cell (copper and copper oxide). 1904 - George Cove Solar electric generator. 1905 - Albert Einstein publishes a paper explaining the photoelectric effect on a quantum basis. 1913 - William Coblentz receives US1077219, "Solar cell." 1914 - Sven Ason Berglund patents "methods of increasing the capacity of photosensitive cells." 1916 - Robert Millikan conducts experiments and proves the photoelectric effect. 1918 - Jan Czochralski produces a method to grow single crystals of metal. Decades later, the method is adapted to