William Grylls Adams (1836-1915), an English professor of Natural Philosophy at King’s College, London. He discovered that the solid material 'selenium' produced electricity when exposed to light. This became known as the photoelectric effect, which the German physicist Heinrich Hertz demonstrated experimentally in 1887. Although selenium solar cells had low efficiencies and would be replaced with silicon cells, Adams’ work proved that a solid material could change light into electricity without heat or without moving parts.
William Grylls Adams, Biographical Information (Navigational Aids for the History of Science, Technology & the Environment)