<Ul> <Li> 1776 - Horace de Saussure, a Swiss physicist, invented the first solar oven . The solar oven used sunlight to heat meals and no electricity was required nor generated . </Li> </Ul> <Li> 1776 - Horace de Saussure, a Swiss physicist, invented the first solar oven . The solar oven used sunlight to heat meals and no electricity was required nor generated . </Li> <Ul> <Li> 1839 - Alexandre Edmond Becquerel observes the photovoltaic effect via an electrode in a conductive solution exposed to light . </Li> <Li> 1873 - Willoughby Smith finds that selenium shows photoconductivity . </Li> <Li> 1877 - W.G. Adams and R.E. 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 . </Li> <Li> 1878 - Augustin Mouchot displays a solar power generator at the Universal Exhibition in Paris . </Li> <Li> 1883 - Charles Fritts develops a solar cell using selenium on a thin layer of gold to form a device giving less than 1% efficiency . </Li> <Li> 1887 - Heinrich Hertz investigates ultraviolet light photoconductivity and discovers the photoelectric effect </Li> <Li> 1887 - James Moser reports dye sensitised photoelectrochemical cell . </Li> <Li> 1888 - Edward Weston receives patent US389124, "Solar cell," and US389125, "Solar cell ." </Li> <Li> 1888 - 91 - Aleksandr Stoletov creates the first solar cell based on the outer photoelectric effect </Li> <Li> 1894 - Melvin Severy receives patent US527377, "Solar cell," and US527379, "Solar cell ." </Li> <Li> 1897 - Harry Reagan receives patent US588177, "Solar cell ." </Li> <Li> 1899 - Weston Bowser receives patent US598177, "solar storage ." </Li> </Ul> <Li> 1839 - Alexandre Edmond Becquerel observes the photovoltaic effect via an electrode in a conductive solution exposed to light . </Li>

When was solar energy first discovered or invented