Before the first modern solar panels were invented by Bell Laboratories in 1954, the history of solar energy was one of fits and starts, driven by individual inventors and scientists. Then the space and defense industries recognized its value, and by the late 20th century, solar energy had emerged as a promising but still costly alternative to fossil fuels.
In the 21st century, the industry has come of age, developing into a mature and inexpensive technology that is rapidly replacing coal, oil, and natural gas in the energy marketplace. This timeline highlights some of the major pioneers and events in the emergence of solar technology.
The Age of Discovery (19th-early 20th century)
Physics flourishes in the mid-19th century with experiments in electricity, magnetism, and the study of light, among other breakthroughs. The basics of solar energy are part of that discovery, as inventors and scientists lay the groundwork for much of the subsequent history of the technology.
1839: At the age of 19, Frenchman Alexandre-Edmond Becquerel creates the world’s first photovoltaic cell in his father’s laboratory. His studies of light and electricity inspire later developments in photovoltaics. Today, the Becquerel Prize is given out annually by the European Photovoltaic Solar Energy Conference and Exhibition.
1861: Mathematician and physicist Auguste (or Augustin) Mouchout patents a solar-powered motor.
1873: Electrical engineer Willoughby Smith discovers the photovoltaic effect in selenium.
What Is the Photovoltaic Effect?
The photovoltaic effect is the key to solar PV technology. A combination of physics and chemistry, the photovoltaic effect occurs when an electric current is created in a material when it is exposed to light.
1876: W. G. Adams, professor of Natural Philosophy at King’s College, London, discovers “the change in the electrical resistance of the selenium due to radiant heat, light, or chemical action.”
1882: Abel Pifre builds a “solar engine” that generates enough electricity to power his solar printing press, which he displays in the Tuileries Gardens in Paris, France (pictured below).
1883: Inventor Charles Fritts develops the first solar cell using selenium coated with gold. It has less than one percent efficiency in converting solar radiation to electricity.
1883: Inventor John Ericsson develops a “sun motor” which uses parabolic trough construction (PTC) to focus solar radiation to run a steam boiler. PTC is still used in solar thermal power stations.
1884: Charles Fritts installs solar panels on a rooftop in New York City.
1903: Entrepreneur Aubrey Eneas’s Solar Motor Company begins marketing solar-driven steam engines to fuel irrigation projects in Pasadena, California. The company soon fails.
1912-1913: Engineer Frank Shuman’s Sun Power Company uses PTC to build the world’s first solar thermal power plant.
The Age of Understanding (late 19th-early 20th century)
The emergence of modern theoretical physics helps create a foundation for a greater understanding of photovoltaic energy. Quantum physics’s descriptions of the subatomic world of photons and electrons unveil the mechanics of how packets of incoming light disrupt electrons in silicon crystals in order to generate electric currents.
1888: Physicist Wilhelm Hallwachs describes the physics of photovoltaic cells in what is now known as the Hallwachs effect.
1905: Albert Einstein publishes “On a Heuristic Viewpoint Concerning the Production and Transformation of Light,” explaining how light creates an electric current by knocking electrons out of the atoms in certain metals.
1916: Chemist Jan Czochralski invents a method for creating single crystals of metal. This becomes the basis for creating semiconductor wafers still used in electronics, including solar cells.
1917: Albert Einstein gives a theoretical foundation to photovoltaics by introducing the notion that lights act as packets carrying electromagnetic force.
1929: Physicist Gilbert Lewis coins the term “photons” to describe Einstein’s packets of electromagnetic energy.
The Age of Development (mid-20th century)
Serious research into the development of solar technology, based on the invention of monocrystalline silicon solar cells, leaves the laboratory. Like many other technologies, it emerges out of research conducted for the U.S. defense and space industries, and its first successful use is in satellites and space exploration. These uses demonstrate the effectiveness of solar energy, though most of the technology is still too expensive to be commercialized.
1941: Bell Laboratories engineer Russell Ohl files a patent for the first monocrystalline silicon solar cell.
1947: Passive solar houses become popular due to post-war energy scarcity.
1951: Solar cells made from germanium are constructed.
1954: Bell Laboratories produces the first efficient silicon solar cell. While weak compared to current cells, these cells are the first that can generate significant amounts of electricity—at about 4% efficiency.
1955: The first solar-powered telephone call is made.
1956: General Electric introduces the first solar-powered radio. It can operate during both daylight and darkness.
1958: Vanguard I is the first spacecraft to be powered by solar panels.
1960: A car with a solar-panel roof and a 72-volt battery drives around London, England.
1961: The United Nations sponsors a conference on the use of solar energy in the developing world.
1962: 3,600 cells from Bell Laboratories power Telstar, the first solar-powered communications satellite.
1967: The Soviet Union’s Soyuz 1 becomes the first solar-powered spacecraft to carry humans.
1972: A solar-powered watch, the Synchronar 2100, goes on the market.
Who Invented Solar Panels?
Charles Fritts was the first person to generate electricity using solar panels—in 1884—but it would be another 70 years before they became efficient enough to be useful. The first modern solar panels, with a still-meager 4% efficiency, were developed by three researchers at Bell Laboratories, Daryl Chapin, Gerald Pearson, and Calvin Fuller. Those three pioneers stood on the sometimes-overlooked shoulders of their Bell Labs predecessor Russel Ohl, who discovered how silicon crystals acted as semiconductors when exposed to light.
The Age of Growth (late 20th century)
The energy crisis of the early 1970s spurs the first commercialization of solar technology. Shortages of petroleum in the industrialized world lead to slow economic growth and high oil prices. In response, the U.S. government creates financial incentives for commercial and residential solar systems, research and development institutes, demonstration projects for the use of solar electricity in government buildings, and a regulatory structure that still supports the solar industry today. With these incentives, solar panels go from a cost of $1,865/watt in 1956 to $106/watt in 1976 (prices adjusted to 2019 dollars).
1973: An oil embargo led by Arab nations drives oil prices up 300%.
1973: The University of Delaware constructs Solar One, the first building powered solely by solar energy.
1974: The Solar Heating and Cooling Demonstration Act calls for the use of solar energy in federal buildings.
1974: The International Energy Agency is founded to study and forecast energy markets.
1974: The U.S. Energy Research and Development Administration (ERDA) is created in order to foster the commercialization of solar energy.
1974: The Solar Energy Industries Association (SEIA) is formed to represent the interests of the solar industry.
1977: The Solar Energy Research Institute is established by Congress. It is now the National Renewable Energy Laboratory (NREL).
1977: The world production of photovoltaic cells exceeds 500 kW.
1977: The U.S. Department of Energy is established.
1978: The Public Utility Regulatory Policies Act (PURPA) of 1978 lays the foundation for net metering by requiring utilities to purchase electricity from “qualifying facilities” that meet certain standards on energy source and efficiency.
1978: The Energy Tax Act creates the Investment Tax Credit (ITC) and the Residential Energy Credit to provide incentives to the purchase of solar systems.
1979: The Iranian Revolution interrupts oil exports from the Middle East, forcing oil prices up.
1979: U.S. President Jimmy Carter installs solar panels on the White House roof, later dismantled by President Ronald Reagan.
1981: Funded by the United States and Saudi Arabia, the first concentrating PV system goes into operation.
1981: Solar Challenger becomes the world’s first solar aircraft capable of flying long distances.
1981: Solar One, a pilot solar thermal project in the Mojave Desert near Barstow, California, is completed by the U.S. Department of Energy.
1982: The first large-scale solar farm is built near Hesperia, California.
1982: The Sacramento Municipal Utility District commissions its first solar electricity-generating facility.
1985: Silicon cells that can reach 20% efficiency are created by the Centre for Photovoltaic Engineering at the University of New South Wales in Australia.
1985: Lithium-ion batteries, later used to store renewable energy, are developed.
1991: The first lithium-ion batteries reach commercial production.
1992: The Investment Tax Credit is made permanent by Congress.
2000: Germany creates a feed-in-tariff program to stimulate the solar industry.
What Is a Feed-In-Tariff?
A feed-in-tariff is a government program that guarantees above-market prices for producers of renewable energy, usually involving long-term contracts to give investors certainty in the early development of new technologies, before they are commercially able to stand on their own.
The Age of Maturity (21st century)
GPA Photo Archive / Flickr / CC BY-NC 2.0
From an expensive but scientifically sound technology, solar energy benefits from continued government support to become the lowest-cost energy in history. Its success follows the S-curve, where initial growth of a technology is slow and driven only by early adopters, then experiences explosive growth as economies of scale allow production costs to decline and supply chains to expand. While solar modules cost $106/watt in 1976 (in 2019 dollars), they drop to just $0.38/watt in 2019, with 89% of that drop happening since 2010.
2001: Home Depot begins selling residential solar power systems.
2001: Suntech Power is founded in China and becomes a world leader in solar technology.
2006: The California Public Utilities Commission approves the California Solar Initiative to provide incentives for solar development.
2008: NREL sets a world record for solar cell efficiency at 40.8%.
2009: The International Renewable Energy Agency (IRENA) is founded.
2009: The American Recovery and Reinvestment Act (ARRA) provides $90 billion in clean energy investments and tax incentives, including subsidies and loan guarantees for solar energy projects.
2009: China introduces feed-in-tariffs to stimulate growth in the solar industry.
2010: U.S. President Barack Obama re-install solar panels and a solar water heater at the White House.
2011: Solyndra bankruptcy and investment fiasco slows solar industry growth.
2013: World-wide solar PV installations pass 100 gigawatts.
2015: Tesla introduces the lithium-ion Powerwall battery pack to allow rooftop solar owners to store electricity.
2015: China becomes the world’s leader in installed solar system capacity, surpassing Germany.
2015: Google launches Project Sunroof to help homeowners judge the feasibility of rooftop solar.
2016: Solar installations in the United States reach one million.
2016: Solar Impulse 2 takes the first zero-emissions flight around the world.
2016: Las Vegas, Nevada, becomes the largest city government in America to be run entirely on renewable energy, including from solar panel trees in front of City Hall.
2017: The solar industry employs more people in electricity generation in the U.S. than do fossil fuel industries.
2019: The first offshore floating solar farm is installed in the Dutch North Sea.
2020: It is cheaper to build a new solar plant than it is to continue operating an existing coal plant.
2020: California requires all new homes to have solar panels.
2020: The International Energy Agency states that “Solar is the new king of the electricity markets.”
2021: Apple, Inc. announces it was constructing the world’s largest lithium-ion battery to stare energy from its 240 megawatt-hour solar farm in California.