Before 600 BC someone had figured out how to start a fire using the sun's light and a magnifying glass.
In 1767, a solar oven was invented by Horace de Saussure.
In 1876, William Grylls Adams and Richard Day discovered that selenium produced electricity when exposed to sunlight. Werner von Siemens said that the discovery was very important. Selenium was not yet a cost-efficient source of power, but it was a beginning.
In 1883, Charles Fritts made selenium-based solar cells.
In a paper published in 1905, Albert Einstein formulated the photon theory of light.
In the 1920's solar warer-heating systems began to be installed in houses and apartment buildings in Florida and California.
In 1953, Calvin Fuller, Gerald Pearson and Daryl Chapin made the first silicon solar cells, efficient enough to power small electrical devices.
In 1956 solar cells were sold commercially for the first time. These were sold powering novelty devices and not yet as practical generators of electricity.
In 1961 the United Nations held a conference on "Solar Energy in the Developing World."
The Telstar satellite became the first solar-powered satellite in 1962, and in 1967, the Soyez 1 was the first manned spacecraft using only solar power while in orbit.
In 1971, J Baldwin of Integrated Living Systems developed the first building powered exclusively by solar and wind.
In 1972, a laboratory devoted exclusively to photovoltaic research opened at the University of Delaware. In 1973, the lab has created ahiuse, called Solar One, powered exclusively by solar.
In the 1990's, a grid-supported photovoltaic system was completed and installed in Kerman, California by Pacific Gas & Electric.
In 2004, Governor Arnold Schwarzenegger of California proposed a program to have solar roofs on one million buildings in the state by 2017.
Currently, Hillary Clinton supports a plan to install 500 million solar panels nationwide by 2021.