1839 - Edmond Becquerel, a young physicist working in France, observed and discovered the photovoltaic effect, a process that produces a voltage or electric current when exposed to light or radiant energy.

1873 - Willoughby Smith, an English engineer, discovered photoconductivity in solid selenium.

1876 - William Grylls Adams along with a student of his, Richard Day, discovered that when selenium was exposed to light, it produced electricity.

1883 - American inventor Charles Fritts created the first solar cell by coating selenium with a thin layer of gold. Fritts reported that the selenium module produced a current that is continuous, constant and of considerable force.

1905 - Albert Einstein publishes a paper on the photoelectric effect. He formulated the photon theory of light, which describes how light can “liberate” electrons on a metal surface. In 1921, 16 years after he submitted this paper, he was awarded the Nobel Prize for the scientific breakthroughs he had discovered.

1954 - David Chapin, Calvin Fuller and Gerald Pearson of Bell Labs are credited with the world’s first photovoltaic cell (solar cell). It was the first device that converted sunlight into electrical power.

1956 - The first solar cells are available commercially. At $300 for a 1 watt solar cell, the cost is far from the reach of everyday people.

1950’s and early 1960’s - Satellites in the US’s and Soviet’s space program were powered by solar cells and in the late 1960’s solar power was basically the standard for powering space bound satellites.

1974 - The emergence of energy crisis emerged in the US spurred Congress to pass the Solar Energy Research, Development and Demonstration Act, committed to make solar viable and affordable and market it to the public.

1973 - University of Delaware is credited with creating one of the first solar buildings, “Solar One,” The construction ran on a combination of solar thermal and solar photovoltaic power. The building didn’t use solar panels; instead, solar was integrated into the rooftop.

1970’s to the 1990’s - Usage of solar cells began showing up on railroad crossings, in remote places to power homes, Australia used solar cells in their microwave towers to expand their telecommunication capabilities. Even desert regions saw solar power bring water to the soil where line fed power was not an option.

1979 - US President Jimmy Carter installs solar panels on the White House.

2000 - Worldwide solar PV installations surpass 1 GW. The US alone hits 1 GW in 2008 and surpasses 25 GW in 2015.

2017 - The installed cost of solar falls to record lows.