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History of Solar Energy

The solar panels we see today aren't something that came about over the past few years. Or even decades. Over 150 years ago, a discovery that some materials could produce electricity when exposed to light inspired various renown scientists over many years to experiment and study the effect, eventually leading to the creation of the first solar cell. It took many more years of advancements in technology to create higher efficiency cells and numerous forward-thinking people to make solar energy acceptable to the world.

Below is a timeline of significant people and events who have helped to shape solar energy as we recognize it today.

1839 - French physicist Alexandre-Edmond Becquerel discovered that certain materials could produce small amounts of electricity when exposed to light. This observation became known as the photovoltaic effect and is the operating principle of the solar cell.

1864 - Scottish physicist and mathematician James Clerk Maxwell proposed that electricity, magnetism, and light are demonstrations of the electromagnetic field and that light travels in the form of a wave. His wave model of light was highly revered and accepted within the scientific community.1, 2

1883 - American inventor Charles Fritts created the first working solar cell using a selenium semiconductor material coated with a thin layer of gold. It had a conversion efficiency of about 1%.3

1891 - Russian physicist Aleksandr Stoletov discovered the direct proportionality between the intensity of light and induced photoelectric current. 4

1899 - British physicist J.J. Thomson, who was influenced by Maxwell's work, deduced that atoms contained negatively charged particles called "electrons."

1900 - German physicist Max Planck determined that light was emitted through tiny energy packets, called "quanta." Quanta was later renamed as "photon."5

1905 - German physicist Albert Einstein published the most comprehensive theoretical work about the photovoltaic effect. In his paper, titled "On a Heuristic Viewpoint Concerning the Production and Transformation of Light," he expanded on Planck's photon theory by writing an equation for the photoelectric effect that explained why the energy of photoelectrons were dependent on only the frequency of the incident of light, not its intensity. His concept was strongly resisted because it contradicted Maxwell's wave theory of light.

1915 - After undertaking a decade long experimental program to test Einstein's theory and prove it wrong, American physicist Robert Andrews Millikan actually wound up confirming Einstein's predictions in every detail. 6

1918 - Polish chemist Jan Czochralski discovered a method of crystal growth used to obtain single crystals of semiconductors. This later enabled the production of monocrystalline solar cells. 7

1922 - Einstein was awarded the 1921 Nobel Prize in Physics for his 1905 paper, which was now accepted as accurate.

1939 - American engineer Russell Ohl of AT&T's Bell Laboratories discovered the PN barrier (later called the p-n junction) when he realized that shining a light on a silicon crystal would cause a spontaneous electric current to trickle through it. The p-n junction is a critical element in the production of solar cells. 8, 9

1941 - Ohl patented the modern solar cell - construction of the first silicon monocrystalline solar cell

1954 - G.L. Pearson, Daryl Chapin, and Calvin Fuller of Bell Labs demonstrated a silicon solar cell capable of 6% energy conversion efficiency when used in direct sunlight. This was considered highly efficient at the time.

1955 - Hoffman Electronics' Semiconductor Division created a commercial solar with a 2% efficiency for $25 per cell ($1,785 per Watt)

1958 - US Signal Corps Laboratories created a silicon solar cell that was more resistant to radiation damage and better suited for space. The first solar powered satellite, Vanguard I, was launched with a 0.1 Watt, 100 cm2 solar panel.

1959 - Hoffman Electronics introduces the use of a grid contact on their commercial solar cell, thus reducing the cell's resistance but boosting its efficiency to 10%.

1961 - The United Nations holds a "Solar Energy in the Developing World" conference

1967 - The Soyuz 1 became the first manned spacecraft to be powered by solar cells.

1971 - The first space station, Salyut 1 (DOS-1), is launched by the USSR. It is powered by solar cells.

1974 - Industrial designer James T. Baldwin co-developed the world's first building, located in New Mexico, that was heated and powered exclusively by solar and wind power.

1976 - RCA Laboratories created the first amorphous silicon PV cell, which has an efficiency of 1.1%.

1979 - President Jimmy Carter installed solar panels on the White House and promoted incentives for solar energy systems during the energy crisis. The panels were later removed in 1986 during roof maintenance and never replaced.

1980 - The Institute of Energy Conservation at University of Delaware developed the first thin-film solar cell exceeding 10% efficiency.

1983 - Worldwide PV production and installations exceeded 21.3 megawatts

1985 - The Centre for Photovoltaic Engineering created 20% efficient silicon solar cells.

1991 - Under the direction of President George H. W. Bush, the United States Department of Energy established the National Renewable Energy Laboratory (NREL), but their Solar Energy Research Facility isn't established until two years later.

1994 - NREL developed the first solar cell to exceed 30% conversion efficiency.

1999 - Worldwide PV installations reached 1,000 megawatts.

2002 - President George W. Bush installed a 9 kW PV panel on the roof of a White House grounds maintenance building.

2006 - A solar cell with 40% efficiency is produced.

2008 - NREL produced a solar cell with 40.8% efficiency. 10