History of photovoltaics

Should you think this web site needs improvement, don't hesitate to let me know. I'll be happy of any constructive criticism. Any comments on terminology and web site content are appreciated. E-mail them to:

A walk trough time

"The essentials of a phenomenom are best understood if one tries to explore their rise from the very beginnings."
(Aristotle)

Vanguard I sattelite before launching Photovoltaic array used in Apollo programme Photovoltaic module used in extraterrestrial applications in 1983

Vanguard I satellite before launching, Apollo solar array, solar module used in space applications in 1983
(source: NASA NIX)

The story of photovoltaics and how it all began in 1839 as a coincidence, just like many other discoveries in the past, such as penicillin, is a very interesting reading. The story will take you through some facts, persons and events, which have marked the history of photovoltaics.

"Being desirous of obtaining a more suitable high resistance for use at the Shore Station in connection with my system of testing and signalling during the submersion of long submarine cables, I was induced to experiment with bars of selenium - a known metal of very high resistance. I obtained several bars, varying in length from 5 cm to 10 cm, and of a diameter from 1.0 mm to 1.5 mm. Each bar was hermetically sealed in a glass tube, and a platinum wire projected from each end for the purpose of connection..."

(Willoughby Smith: Letter to Latimer Clark, Wharf Road, 4^th February 1873)

1839 - 1899: Discovery of basic phenomena and properties of PV materials

Discovery of photovoltaic effect

A physical phenomenon allowing light-electricity conversion - photovoltaic effect, was discovered in 1839 by the French physicist Alexandre Edmond Becquerel. Experimenting with metal electrodes and electrolyte he discovered that conductance rises with illumination.

First solar cells

Willoughby Smith discovered photovoltaic effect in selenium in 1873. In 1876, with his student R. E. Day, William G. Adams discovered that illuminating a junction between selenium and platinum also has a photovoltaic effect. These two discoveries were a foundation for the first selenium solar cell construction, which was built in 1877. Charles Fritts first described them in detail in 1883.

Other interesting phenomena

In 1887, Heinrich Hertz discovered that ultraviolet light changes the voltage at which sparks between two metal electrodes would be initiated.

1900 - 1949: Theoretical explanation of the photovoltaic effect and first solar cells

Theoretical explanation of the photovoltaic effect

The author of the most comprehensive theoretical work about the photovoltaic effect was Albert Einstein, who described the phenomenon in 1904. For his theoretical explanation he was awarded a Nobel Prize in 1921. Einstein's theoretical explanation was practically proved by Robert Millikan's experiment in 1916.

The first silicon solar cells

In 1918, a Polish scientist Jan Czochralski discovered a method for monocrystalline silicon production, which enabled monocrystalline solar cells production. The first silicon monocrystalline solar cell was constructed in 1941.

The photovoltaic effect in other materials

In 1932, the photovoltaic effect in cadmium-selenide was observed. Nowadays, CdS belongs among important materials for solar cells production.

1950 - 1969: Intensive space research

Intensive laboratory researches

In 1951, the first germanium solar cells have been made. Dr. Dan Trivich of Wayne State University has made some theoretical calculation on solar cell efficiency with different materials, and on solar spectrum wavelengths in 1953. In 1954, the RCA Laboratories published a report on CdS photovoltaic effect. AT&T organized several demonstrations on solar cells functioning the same year. The Bell's Laboratories published the results of the solar cells operation with 4.5 % efficiency. The efficiency was increased to 6 % within a few months.

The first satellites and solar powered cars

In 1955, the preparation on satellite energy supply by solar cells began. Western Electric put for sale commercial licenses for solar cells production. Hoffman Electronics-Semiconductor Division introduced a commercial photovoltaic product with 2 % efficiency for US$ 25 per cell with 14 mW peak power. The energy cost was US$ 1,785 per W. In 1957, Hoffman Electronics introduced a solar cell with 8 % efficiency. A year later, in 1958, the same company introduced a solar cell with 9 % efficiency. The first radiation proof silicon solar cell was produced for the purposes of space technology the same year. On 17^th March, the first satellite powered by solar cells, Vanguard I, was launched. The system ran continuously for 8 years. Two other satellites, Explorer III and Vanguard II, were launched by Americans, and Sputnik III by Russians. The first telephone repeater powered by solar cells was built In Americus, Georgia. In 1959, Hoffman Electronics introduced commercially available solar cells with 10 % efficiency. Americans launched the satellites Explorer VI with photovoltaic field of 9,600 cells and Explorer VII. In 1960, Hoffman Electronics introduced yet another solar cell with 14 % efficiency. The first sun-powered automobile was demonstrated in Chicago, Illinois on August 31^st, 1955.

The first photovoltaic conferences

A United Nation's conference on solar energy application in developing countries took place in 1961. The Defence Studies Institute organized the first photovoltaic conference the same year in Washington. In 1962, the first commercial telecommunications satellite Telstar, developed by Bell Laboratories, was launched. The photovoltaic system peak power for satellite power supply was 14 W. The second photovoltaic conference took place in Washington.

The first solar modules

In 1963, Sharp Corporation developed the first usable photovoltaic module from silicon solar cells. The biggest photovoltaic system at the time, the 242 W module field was set up in Japan. A year later, in 1964, Americans applied a 470 W photovoltaic field in the Nimbus space project.

Intensive research on photovoltaic technologies for extraterrestrial application

In 1965, the Japanese scientific programme for Japanese satellite launch commenced. The following year, in 1966, an astronomic observatory with 1 kW peak power photovoltaic module field was tracked in the earthly orbit. In 1968, the OVI-13 satellite with two CdS panels was launched.

Skylab - wings with solar cells are used for power supply

Skylab (source: NASA NIX)

The first bigger company

In 1969, Roger Little established Spire Corporation, which became and still is an important producer of solar cells production equipment.

1970 - 1979: Establishment of large photovoltaic companies

The first application of photovoltaic technologies on Earth

In 1972, Solar Power Corporation was established. Company started commercial business in 1973 when a sales office in Braintree, Massachusetts was opened. The French implemented a CdS photovoltaic system enabling educational TV programme broadcast in the province of Niger in 1972. A year after, in 1973, Solarex Corporation was established. At the Delaware University a photovoltaic-thermal hybrid system Solar one, one of the first photovoltaic systems for domestic application, was developed. Besides the photovoltaic system, the system incorporated also a warmth keeper of phase changeable materials. A silicon solar cell of US$ 30 per W was produced. In 1974, the Japanese Sunshine project commenced. A year later, in 1975, Solec International and Solar Technology International were established. The American government encouraged JPL Laboratories research in the field of photovoltaic systems for application on Earth the same year.

The first photovoltaic systems for the third world rural areas

In 1976, under NASA protection LeRC commenced photovoltaic system installations for application on Earth, which continued until 1985 and later from 1992 until 1995. The systems were meant for refrigerator, telecommunication equipment, medical equipment, lighting and water pumping power supply as well as for other applications. NASA LeRC introduced several demonstration projects. The first amorphous silicon solar cell was developed by RCA Laboratories the same year. Solec International was established.

The first photovoltaic applications for supply of technologically sophisticated devices on Earth

In 1977, the world production of photovoltaic modules exceeded 500 kW. NASA LeRC commenced implementing photovoltaic systems in six meteorological stations in different locations within USA. NASA LeRC introduced additional trial demonstration projects. Solar Energy Research Institute located in Golden, Colorado launched its operation. In an American Indians reservation NASA LeRC set up a 3.5 kW system - the first system ever to satisfy the demands of the entire village. It was used for water pumping and power supply of 15 households. In 1979, ARCO Solar of Camarillo, California, built the biggest solar cells and photovoltaic systems production plant premises at that time. NASA LeRC built a 1.8 kW water pumping photovoltaic system in Burkina Faso. The system peak power was enlarged to 3.6 kW the same year. In Mt. Laguna, California, a trial 60 kW hybrid diesel-photovoltaic system was built for radar station power supply.

1980 - 1989: Large standalone systems installations

Large standalone photovoltaic systems

Many important events in the field of photovoltaics appeared in 1980. ARCO Solar was the first to produce photovoltaic modules with peak power of over 1 MW per year. A trial photovoltaic system installation was made in the centre of the volcano observatory in Hawaii. A new company BP appeared in the market. ARCO Solar built a 105.6 kW system in the State of Utah. The modules integrated in the system were produced by Motorola, ARCO Solar and Spectrolab. A year later, in 1981, NASA LeRC began to build systems for vaccine refrigerators power supply on 30 locations around the globe (the project was closed in 1984). Solar Challenger, the first plane ever powered by solar energy, took off. A system with peak power of 90.4 kW with modules produced by Solar Power Corporation was built in Square Shopping Center in Lovington, New Mexico. A similar system was built for Beverly High School in Beverly, Massachusetts. A seawater desalination system with 10.8 kW peak power was built in Jeddah, Saudi Arabia the same year. Helios Technology, the oldest European solar cells producer, was established. The world production of photovoltaic modules exceeded 9.3 MW in 1982. Solarex established Solarex Aerospace division the same year. At the Vienna conference NASA LeRC introduced a trial case of terrestrial satellite reception station and public lighting electricity supply. Volkswagen began testing photovoltaic systems placed on vehicle roofs with 160 W peak power for vehicle start up. Solarex production premises rooftops in Frederick, Maryland, were equipped with photovoltaic systems with 200 kW peak power. ARCO Solar built a 1 MW PV power plant with modules on over 108 double-axis trackers in Hesperia, California.

Solar cars

A year later, in 1983, the world production of photovoltaic modules exceeded 21.3 MW peak power, with product worth of US$ 250 millions. Solar Trek vehicle with photovoltaic system of 1 kW drove 4,000 km in twenty days of Australia Race. The maximum speed was 72 km/h, and the average speed was 24 km/h. The same year the vehicle surpassed the distance of 4,000 km between Long Beach, California, and Daytona Beach, Florida, in 18 days. Solarex Corporation bought an amorphous cells production technology from cells producer RCA and built its own trial power plant in Newtown, Pennsylvania. ARCO Solar built a 6 MW photovoltaic power plant as a subsystem of the public electricity grid for Pacific Gas and Electric Company application in California. The system satisfied the demand of 2,000 to 2,500 households. Solar Power Corporation built four standalone photovoltaic systems for the needs of a village in Tunisia with total peak power of 31 kW per system. A 1.8 kW photovoltaic system was built to satisfy the needs of the local hospital in Guyana. The applications, such as vaccine refrigerator, indoor lighting, ordination lighting and radio appliance were powered by the system. The system was planned and built by NASA Lewis Research Center and Solarex. A similar yet more powerful photovoltaic system of 4 kW was set up in Ecuador. A 1.8 kW photovoltaic system was set up in Zimbabwe for the same purpose. Solarex Corporation merged with Amoco Solar Company, owned by Standard Oil Company.

The first amorphous solar module

In 1984, a 1 MW photovoltaic power plant began to operate in Sacramento, California. ARCO Solar introduced the first amorphous modules. NASA LeRC placed 17 photovoltaic systems to satisfy the demands of the local schools, lighting, medical equipment and water pumping in Gabon. BP Solar Systems with EGS donations built a 30 kW photovoltaic system connected to public electric grid nearby Southampton, Great Britain. Solarex Corporation closed the equipment supply for photovoltaic system for Georgetown University Intercultural Center demands with total peak power of 337 kW and 4,464 modules. BP Solar bought Monosolar thin film division, Nortek, Inc.

High efficient silicon solar cells and thin film solar module

In 1985, researches of University of New South Wales in Australia have constructed a solar cell with more than 20 % efficiency. BP built a power plant in Sydney, Australia and shortly after another one nearby Madrid. A photovoltaic system was built in Sulawesi, Indonesia for the purposes of a terrestrial satellite station. In 1986, ARCO Solar introduced a G-4000, the first commercial thin film photovoltaic module.

Solar car races - a new challenge for research labs

In the Pentax World Solar Challenge 1997 race through Australia a General Motors Sunracer vehicle won with average speed of 71 km/h. In 1988, the fourth Tour de Sol race of 350 km in Switzerland and Austria took place. The vehicle categories included photovoltaic supplied vehicles, additional pedals vehicles, commercial photovoltaic supplied vehicles and electric vehicles without photovoltaic supply. The overall award fond was worth SFR 140,000.

Third world projects and new production capacities

Solarex has received the United Nations tender to supply a 50kW system for UN research projects needs in Pakistan. ARCO Solar increased the thin film system production capacities in Camarillo, California to 7 MW per year. ARCO Solar opened production in Japan and Germany. BP Solar got a thin film technology patent for a solar cells production in 1989.

1990 - 1999: Large photovoltaic companies co-operation

Large-scale solar cell producers

In 1990, Energy Conversion Devices Inc. (ECD) and Canon Inc. established a joint company United Solar Systems Corporation for solar cells production. Siemens bought ARCO Solar and established Siemens Solar Industries, which is nowadays one of the biggest photovoltaic companies in the world. Solar Energy Research Institute (SERI) renamed to National Renewable Energy Laboratory (NREL). A year later, in 1991, BP Solar Systems renamed to BP Solar International (BPSI), and became an independent unit within British Petroleum concern. In 1992, a photovoltaic system of 0.5 kW was placed in Antarctica for the laboratory, lighting, personal computers and microwave ovens needs. A silicon solar cell with 20 % efficiency was patented. In 1994, the National Renewable Energy Laboratory's (NREL), and important institution in the field of renewable energy sources in USA, launched its web site on the Internet. DOE built several trial systems for the need of agriculture, hospitals, lighting, water pumping and so on in Brazil. ASE GmbH from Germany purchased Mobil Solar Energy Corporation technology and established ASE Americas, Inc. A year later, in 1995, the first international fond for promotion of photovoltaic system commercialisation was established, which supported projects in India. The World Bank and the Indian Renewable Energy Sources Agency sponsored projects in co-operation with Siemens Solar. In 1996, BP Solar purchased APS production premises in California, and announced a commercial CIS solar cells production. Icar the plane, powered by solar energy, with 3,000 solar cells in total surface of 21 m²flew over Germany.

The world biggest photovoltaic system plans

In 1997, Greece agreed to sponsor the first 5 MW of total planned 50 MW photovoltaic system on Crete. Due to misunderstanding among investors system was not realised. The activities, which will result in 36,400 50 W systems within the next three years, started in Indonesia. In 1999, Solar Cells, Inc. (SCI), True North Partners, and LLC of Phoenix, Arizona merged to First Solar, LLC.

2000 - : Renewable energy and the Stock exchange

Photovoltaics and stock exchange in Europe

Mostly in Germany, some photovoltaic and renewable energy resources companies have shares listed at the stock exchange. Capital mergers in Germany led to large photovoltaic corporation establishments. During 2000 and 2001 production of Japanese producers increased significantly. Sharp and Kyocera each produce modules with peak power equivalent to the annual consumption in Germany, the most demanding European market. Sanyo is close as well.

HELIOS flight

After many years of research and trial flights HELIOS solar powered plane, developed by NASA and AeroVironment Inc., has broken the height record on 13^th August 2001. HELIOS reached the height of almost 30,000 meters.

Large photovoltaic plants in Germany

In period 2002 - 2003 several large power plants were built in Germany. On April 29^th 2003 at that time the world's largest photovoltaic plant was connected to the public grid in Hemau near Regensburg (Bavaria), Germany. The peak power of the "Solarpark Hemau" plant is 4 MW. Due to renewable energy law "EEG" many other large systems up to 5 MWp were built in Germany in year 2004. Some of them are Solarparks Geiseltalsee, Leipzig, Bürstadt, Göttelborn and others.

Literature and more information

Perlin, J.: From Space to Earth - The Story of Solar Electricity; Aatec Publications Ann Arbor Mi, 1999.
Solar Timeline, US department of Energy (484 kB).
NASA Image Exchange - NIX.
IEEE virtual museum - Rusell Ohl.
Inventors - Photovoltaics Timeline.
Wikipedia - Timeline of solar cells; Wikipedia, the free encyclopedia.
California Solar Center - Solar History.
Smith, C.: Revisiting Solar Powers Past (solar thermal energy use in the past).
Women in Science - Maria Telkes.