Where we've been

Solar energy has been used by the planet to power nearly every process since the existence of life. Plants, animals, and most other living things all rely on solar energy. Humans learned how to take advantage of the sun to make their lives more comfortable long, long ago. Check out the Your Thermostat section to learn more about the history of using solar energy to provide passive heating and cooling. The timeline below shows more historical uses of solar energy.
7th Century B.C. Magnifying glass used to concentrate sun's rays to make fire and to burn ants.
3rd Century B.C. Greeks and Romans use burning mirrors to light torches for religious purposes.
2nd Century B.C. As early as 212 BC, the Greek scientist, Archimedes, used the reflective properties of bronze shields to focus sunlight and to set fire to wooden ships from the Roman Empire which were besieging Syracuse. (Although no proof of such a feat exists, the Greek navy recreated the experiment in 1973 and successfully set fire to a wooden boat at a distance of 50 meters.)
20 A.D. Chinese document use of burning mirrors to light torches for religious purposes.
1767 Swiss scientist Horace de Saussure was credited with building the world's first solar collector, later used by Sir John Herschel to cook food during his South Africa expedition in the 1830s.
1800s In frontier America of the nineteenth century, there were little natural resources (wood included, if you lived on the plains). Many industrious people used large metal tanks to heat water naturally, using the sun's energy.
1816 On September 27, 1816, Robert Stirling applied for a patent for his economiser at the Chancery in Edinburgh, Scotland. Lord Kelvin used one of the working models during some of his university classes. This engine was later used in the dish/Stirling system, a solar thermal electric technology that concentrates the sun's thermal energy in order to produce power.
1839 French scientist Edmond Becquerel discovers the photovoltaic effect while experimenting with an electrolytic cell made up of two metal electrodes placed in an electricity-conducting solution, electricity-generation increased when exposed to light.
1860s French mathematician August Mouchet proposed an idea for solar-powered steam engines. In the following two decades, he and his assistant, Abel Pifre, constructed the first solar powered engines and used them for a variety of applications. These engines became the predecessors of modern parabolic dish collectors.
1873 Willoughby Smith discovered the photoconductivity of selenium.
1876 William Grylls Adams and Richard Evans Day discover that selenium produces electricity when exposed to light. Although selenium solar cells failed to convert enough sunlight to power electrical equipment, they proved that a solid material could change light into electricity without heat or moving parts.
1883 Charles Fritts, an American inventor, described the first solar cells made from selenium wafers.
1891 Baltimore entrepreneur Clarence Kemp became the first man to patent a solar thermal system. Kemp successfully marketed his invention to homes up and down the east coast of America. By 1897, a third of the homes in Pasadena, California had water heated by the sun.
1904 Wilhelm Hallwachs discovered that a combination of copper and cuprous oxide is photosensitive.
1905 Albert Einstein published his paper on the photoelectric effect.
1908 William J. Bailley of the Carnegie Steel Company invents a solar collector with copper coils and an insulated box.
1909 William Bailey patented his solar water heating system that separated the storage tank from an element that collected heat from the sun. This enabled the water to be stored in larger quantities inside the home. By 1918, Bailey had sold over 4,000 of his Day and Night Solar Hot Water Heaters.
1912 Parabolic solar collectors, built on a small farming community on the Nile River 15 miles south of Cairo, Egypt, were developed by a Philadelphia inventor named Frank Shuman. Each collector was fitted with a mechanical tracker which kept it automatically tilted to appropriately absorb the sun. The heat collected by these reflectors was used to produce steam to power a series of large water pumps. Together they produced the equivalent of 55 horsepower and were capable of pumping an astonishing 6000 gallons of water per minute, bringing irrigation water to vast areas of arid desert land.
1914 The existence of a barrier layer in photovoltaic devices was noted.
1918 Polish scientist Jan Czochralski developed a way to grow single-crystal silicon.
1920s The discovery of natural gas in California effectively killed the solar thermal industry there.
1921 Albert Einstein wins the Nobel Prize for his theories explaining the photoelectric effect.
1932 Audobert and Stora discover the photovoltaic effect in cadmium sulfide (CdS).
1940s In pre-WW II Florida, over half the homes used solar to heat water. After the war, declining electricity rates put a stop to Florida's solar thermal industry.
1953 Dr. Dan Trivich, Wayne State University, makes the first theoretical calculations of the efficiencies of various materials of different band gap widths based on the spectrum of the sun.
1954 Photovoltaic technology is born in the United States when Daryl Chapin, Calvin Fuller, and Gerald Pearson develop the silicon photovoltaic (PV) cell at Bell Labs. It is the first solar cell capable of converting enough of the sun's energy into power to run everyday electrical equipment. Bell Telephone Laboratories produced a silicon solar cell with 4% efficiency and later achieved 11% efficiency.
1955 Western Electric began to sell commercial licenses for silicon photovoltaic (PV) technologies. Early successful products included PV-powered dollar bill changers and devices that decoded computer punch cards and tape.
Mid-1950s Architect Frank Bridgers designed the world's first commercial office building using solar water heating and passive design. This solar system has been continuously operating since that time and the Bridgers-Paxton Building, is now in the National Historic Register as the world's first solar heated office building.
1956 William Cherry, U.S. Signal Corps Laboratories, approaches RCA Labs' Paul Rappaport and Joseph Loferski about developing photovoltaic cells for proposed orbiting Earth satellites.
1957 Hoffman Electronics achieved 8% efficient photovoltaic cells.
1958 T. Mandelkorn, U.S. Signal Corps Laboratories, fabricates n-on-p silicon photovoltaic cells that could be used in space.
1958 Hoffman Electronics achieves 9% efficient photovoltaic cells.
1958 The Vanguard I space satellite used a small (less than one watt) array to power its radios. Later that year, Explorer III, Vanguard II, and Sputnik-3 were launched with PV-powered systems on board.
1959 Hoffman Electronics achieves 10% efficient, commercially available photovoltaic cells.
1960 Hoffman Electronics achieves 14% efficient photovoltaic cells.
1963 Sharp Corporation succeeds in producing practical silicon photovoltaic modules.
1963 Japan installs a 242-watt, photovoltaic array on a lighthouse, the world's largest array at that time.
1965 Peter Glaser conceives the idea of the satellite solar power station.
1966 NASA launches the first Orbiting Astronomical Observatory, powered by a 1-kilowatt photovoltaic array, to provide astronomical data in the ultraviolet and X-ray wavelengths filtered out by the earth's atmosphere.
1969 The Odeillo solar furnace, located in Odeillo, France was constructed. This featured an 8-story parabolic mirror.
1970s Dr. Elliot Berman, with help from Exxon Corporation, designs a significantly less costly solar cell, bringing price down from $100 a watt to $20 a watt. Solar cells begin to power navigation warning lights and horns on many offshore gas and oil rigs, lighthouses, railroad crossings and domestic solar applications began to be viewed as sensible applications in remote locations where grid-connected utilities could not exist affordably.
1972 The French install a cadmium sulfide (CdS) photovoltaic system to operate an educational television at a village school in Niger.
1972 The Institute of Energy Conversion is established at the University of Delaware to perform research and development on thin-film photovoltaic (PV) and solar thermal systems, becoming the world's first laboratory dedicated to PV research and development.
1973 The University of Delaware builds "Solar One," one of the world's first photovoltaic (PV) powered residences. The system is a PV/thermal hybrid. The roof-integrated arrays fed surplus power through a special meter to the utility during the day and purchased power from the utility at night. In addition to electricity, the arrays acted as flat-plate thermal collectors, with fans blowing the warm air from over the array to phase-change heat-storage bins.
1976 The NASA Lewis Research Center starts installing 83 photovoltaic power systems on every continent except Australia. These systems provide such diverse applications as vaccine refrigeration, room lighting, medical clinic lighting, telecommunications, water pumping, grain milling, and classroom television. The Center completed the project in 1995, working on it from 1976-1985 and then again from 1992-1995.
1976 David Carlson and Christopher Wronski, RCA Laboratories, fabricate first amorphous silicon photovoltaic cells.
1977 The U.S. Department of Energy launches the Solar Energy Research Institute "National Renewable Energy Laboratory", a federal facility dedicated to harnessing power from the sun.
1977 Total photovoltaic manufacturing production exceeds 500 kilowatts.
1978 NASA's Lewis Research Center dedicates a 3.5-kilowatt photovoltaic (PV) system it installed on the Papago Indian Reservation located in southern Arizona, the world's first village PV system. The system is used to provide for water pumping and residential electricity in 15 homes until 1983, when grid power reached the village. The PV system was then dedicated to pumping water from a community well.
1980 ARCO Solar becomes the first company to produce more than 1 megawatt of photovoltaic modules in one year.
1980 At the University of Delaware, the first thin-film solar cell exceeds 10% efficiency using copper sulfide/cadmium sulfide.
1981 Paul MacCready builds the first solar-powered aircraft, the Solar Challenger, and flies it from France to England across the English Channel. The aircraft had over 16,000 solar cells mounted on its wings, which produced 3,000 watts of power.
1982 The first, photovoltaic megawatt-scale power station goes on-line in Hisperia, California.
It has a 1-megawatt capacity system, developed by ARCO Solar, with modules on 108 dual-axis trackers.
1982 Australian Hans Tholstrup drives the first solar-powered car, the Quiet Achiever, almost 2,800 miles between Sydney and Perth in 20 days, 10 days faster than the first gasoline-powered car to do so.
1982 The U.S. Department of Energy, along with an industry consortium, begins operating Solar One, a 10-megawatt central-receiver demonstration project. The project established the feasibility of power-tower systems, a CSP technology. In 1988, the final year of operation, the system could be dispatched 96% of the time.
1982 Volkswagen of Germany begins testing photovoltaic arrays mounted on the roofs of Dasher station wagons, generating 160 watts for the ignition system.
1983 Solar Design Associates completes a stand-alone, 4-kilowatt powered home in the Hudson River Valley.
1985 The University of South Wales breaks the 20% efficiency barrier for silicon solar cells under 1-sun conditions.
1986 The world's largest solar thermal facility, located in Kramer Junction, California, was commissioned.
1986 ARCO Solar releases the G-4000, the world's first commercial thin-film power module.
1992 University of South Florida develops a 15.9% efficient thin-film photovoltaic cell made of cadmium telluride, breaking the 15% barrier for the first time for this technology.
1994 First solar dish generator using a free-piston Stirling engine is tied to a utility grid.
1994 The National Renewable Energy Laboratory develops a solar cell, made from gallium indium phosphide and gallium arsenide, that becomes the first one to exceed 30% conversion efficiency.
1996 The U.S. Department of Energy, along with an industry consortium, begins operating Solar Two, an upgrade of its Solar One concentrating solar power tower project. Operated until 1999, Solar Two demonstrated how solar energy can be stored efficiently and economically so that power can be produced even when the sun isn't shining.
1998 Subhendu Guha, a noted scientist for his pioneering work in amorphous silicon, led the invention of flexible solar shingles, a roofing material and state-of-the-art technology for converting sunlight to electricity.
1999 The National Renewable Energy Laboratory achieves a new efficiency record for thin-film photovoltaic solar cells. The measurement of 18.8 percent efficiency for the prototype solar cell topped the previous record by more than 1 percent.
1999 Cumulative worldwide installed photovoltaic capacity reaches 1000 megawatts.
2000 First Solar begins production in Perrysburg, Ohio, at the world's largest photovoltaic manufacturing plant with an estimated capacity of producing enough solar panels each year to generate 100 megawatts of power.
2001 Home Depot begins selling residential solar power systems in three of its stores in San Diego, California. A year later it expands sales to include 61 stores nationwide.
2001 British Petroleum (BP) and BP Solar announce the opening of a service station in Indianapolis that features a solar-electric canopy.
2002 ATS Automation Tooling Systems Inc. in Canada starts to commercialize an innovative method of producing solar cells, called Spheral Solar technology.