Dates Matter

Dates can really help paint a visual story – a progressive one, at that. If you’re intrigued and would like to read on the time frames related to the evolving history of solar cells, then please enjoy the dates to follow!

The 1800s

• 1839 – Alexandre Edmond Becquerel observes the photovoltaic effect via an electrode in a conductive solution exposed to light.
• 1873 – Willoughby Smith finds that selenium shows photoconductivity.
• 1877 – W.G. Adams and R.E. Day observed the photovoltaic effect in solidified selenium, and published a paper on the selenium cell. ‘The action of light on selenium,’ in “Proceedings of the Royal Society, A25, 113.
• 1883 – Charles Fritts develops a solar cell using selenium on a thin layer of gold to form a device giving less than 1% efficiency.
• 1887 – Heinrich Hertz investigates ultraviolet light photoconductivity and discovers the photoelectric effect.
• 1887 – James Moser reports dye sensitized photoelectrochemical cell.
• 1888 – Edward Weston receives patent US389124, “Solar cell”, and US389125, “Solar cell”.
• 1888-91 – Aleksandr Stoletov creates the first solar cell based on the outer photoelectric effect.
• 1894 – Melvin Severy receives patent US527377, “Solar cell”, and US527379, “Solar cell”.
• 1897 – Harry Reagan receives patent US588177, “Solar cell”.

The 1900s to 1940s

• 1902 – Philipp von Lenard observes the variation in electron energy with light frequency.
• 1904 – Wilhelm Hallwachs makes a semiconductor-junction solar cell (copper and copper oxide).
• 1905 – Albert Einstein publishes a paper explaining the photoelectric effect on a quantum basis.
• 1913 – William Coblentz receives US1077219, “Solar cell”.
• 1914 – Sven Ason Berglund patents “methods of increasing the capacity of photosensitive cells”.
• 1916 – Robert Millikan conducts experiments and proves the photoelectric effect.
• 1918 – Jan Czochralski, a Polish scientist, produces a method to grow single crystals of metal. Decades later, the method is adapted to produce single-crystal silicon.
• 1920s – Solar water-heating systems, utilizing “flat collectors” (or “flat-plate collectors”), relied upon in homes and apartment buildings in Florida and southern California.
• 1932 – Audobert and Stora discover the photovoltaic effect in Cadmium selenide (CdSe), a photovoltaic material still used today.
• 1935 – Anthony H. Lamb (“Tony” Lamb) receives patent US2000642, “Photoelectric device”.
• 1946 – Russell Ohl receives patent US2402662, “Light sensitive device”.
• 1948 – Gordon Teal and John Little adapt the Czochralski method of crystal growth to produce single-crystalline germanium and, later, silicon.

The 1950s

• 1950s – Bell Labs produce solar cells for space activities.
• 1953 – Gerald Pearson begins research into lithium-silicon photovoltaic cells.
• 1954 – Bell Labs announces the invention of the first modern silicon solar cell. Shortly afterward, they are shown at the National Academy of Science Meeting. These cells have about 6% efficiency. The New York Times forecasts that solar cells will eventually lead to a source of “limitless energy of the sun”.
• 1955 – Western Electric licenses commercial solar cell technologies. Hoffman Electronics-Semiconductor Division creates a 2% efficient commercial solar cell for $25/cell or $1,785/Watt.
• 1957 – AT&T assignors (Gerald L. Pearson, Daryl M. Chapin, and Calvin S. Fuller) receive patent US2780765, “Solar Energy Converting Apparatus”. They refer to it as the “solar battery”. Hoffman Electronics creates an 8% efficient solar cell.
• 1958 – T. Mandelkorn, U.S. Signal Corps Laboratories, creates n-on-p silicon solar cells, which are more resistant to radiation damage and are better suited for space. Hoffman Electronics creates 9% efficient solar cells. Vanguard I, the first solar powered satellite, was launched with a 0.1W, 100 cm² solar panel.
• 1959 – Hoffman Electronics creates a 10% efficient commercial solar cell, and introduces the use of a grid contact, reducing the cell’s resistance.

The 1960s to 1970s

• 1960 – Hoffman Electronics creates a 14% efficient solar cell.
• 1961 – “Solar Energy in the Developing World” conference is held by the United Nations.
• 1962 – The Telstar communications satellite is powered by solar cells.
• 1963 – Sharp Corporation produces a viable photovoltaic module of silicon solar cells.
• 1964 – Farrington Daniels’ landmark book, Direct Use of the Sun’s Energy, published by Yale University Press.
• 1967 – Soyuz 1 is the first manned spacecraft to be powered by solar cells
• 1967 – Akira Fujishima discovers the Honda-Fujishima effect which is used for hydrolysis in the photoelectrochemical cell.
• 1970 – First highly effective GaAs heterostructure solar cells are created by Zhores Alferov and his team in the USSR.
• 1971 – Salyut 1 is powered by solar cells.
• 1973 – Skylab is powered by solar cells.
• 1974 – Florida Solar Energy Center begins.
• 1974 – J. Baldwin, at Integrated Living Systems, co-develops the world’s first building (in New Mexico) heated and otherwise powered by solar and wind power exclusively.
• 1976 – David Carlson and Christopher Wronski of RCA Laboratories create first amorphous silicon PV cells, which have an efficiency of 1.1%.
• 1977 – The Solar Energy Research Institute is established at Golden, Colorado.
• 1977 – President Jimmy Carter installs solar panels on the White House and promotes incentives for solar energy systems.
• 1977 – The world production of photovoltaic cells exceeded 500 kW
• Late 1970s: the “Energy Crisis”; groundswell of public interest in solar energy use: photovoltaic and active and passive solar, including in architecture and off-grid buildings and home sites.

The 1980s

• 1980 – John Perlin and Ken Butti’s landmark book A Golden Thread published, covering 2500 Years of Solar Technology from the Greeks and Romans until the modern day.
• 1980 – The Institute of Energy Conversion at University of Delaware develops the first thin film solar cell exceeding 10% efficiency using Cu2S/CdS technology.
• 1983 – Worldwide photovoltaic production exceeds 21.3 megawatts, and sales exceed $250 million.
• 1984 – 30,000 SF Building-Integrated Photovoltaic [BI-PV] Roof completed for the Intercultural Center of Georgetown University. At the time of the 20th Anniversary Journey by Horseback for Peace and Photovoltaics in 2004 it was still generating an average of one MWh daily as it has for twenty years in the dense urban environment of Washington, DC.
• 1985 – 20% efficient silicon cells are created by the Centre for Photovoltaic Engineering at the University of New South Wales.
• 1986 – ‘Solar-Voltaic DomeTM’ patented by Lt. Colonel Richard T. Headrick of Irvine, CA as an efficient architectural configuration for building-integrated photovoltaics [BI-PV]; Hesperia, CA field array.
• 1986 – President Ronald Reagan removes solar panels from the White House.
• 1988-1991 AMOCO/Enron used Solarex patents to sue ARCO Solar out of the business of a-Si (see Solarex Corp.(Enron/Amoco) v.Arco Solar, Inc.Ddel, 805 Fsupp 252 Fed Digest.)
• 1989 – Reflective solar concentrators are first used with solar cells.

The 1990s

• 1990 – The Cathedral of Magdeburg installs solar cells on the roof, marking the first installation on a church in East Germany.
• 1991 – Efficient Photoelectrochemical cells are developed; the Dye-sensitized solar cell is invented.
• 1991 – President George H. W. Bush directs the U.S. Department of Energy to establish the National Renewable Energy Laboratory (transferring the existing Solar Energy Research Institute).
• 1992 – University of South Florida fabricates a 15.89-percent efficient thin-film cell
• 1993 – The National Renewable Energy Laboratory’s Solar Energy Research Facility is established.
• 1994 – NREL develops a GaInP/GaAs two-terminal concentrator cell (180 suns) which becomes the first solar cell to exceed 30% conversion efficiency.
• 1996 – The National Center for Photovoltaics is established. Graetzel, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland achieves 11% efficient energy conversion with dye-sensitized cells that use a photoelectrochemical effect.
• 1999 – Total worldwide installed photovoltaic power reached 1000 megawatts.

The 2000s

• 2002 – President George W. Bush installed a 9 kW ‘building-integrated photovoltaics’ panel on the roof of a grounds maintenance building at the White House for the National Parks Service. Also installed were two solar water heating systems.
• 2004California Governor Arnold Schwarzenegger proposed Solar Roofs Initiative for one million solar roofs in California by 2017.
• 2004 – Kansas Governor Kathleen Sebelius issued a mandate for 1,000 MWp renewable electricity in Kansas by 2015 per Executive Order 04-05.
• 2006 – Polysilicon use in photovoltaics exceeds all other polysilicon use for the first time.
• 2006 – California Public Utilities Commission approved the California Solar Initiative (CSI), a comprehensive $2.8 billion program that provides incentives toward solar development over 11 years.
• 2006 – New World Record Achieved in Solar Cell Technology – New Solar Cell Breaks the “40 Percent Efficient” Sunlight-to-Electricity Barrier.

2007 to Present

• 2007 – Construction of Nellis Solar Power Plant, a 15 MW PPA installation.
• 2007 – The Vatican announced that in order to conserve Earth’s resources they would be installing solar panels on some buildings, in “a comprehensive energy project that will pay for itself in a few years”.
• 2007 – Google solar panel project begins operation.
• 2007 – University of Delaware claims to achieve new world record in Solar Cell Technology without independent confirmation – 42.8% efficiency.
• 2007 – Nanosolar ships the first commercial printed CIGS, claiming that they will eventually ship for less than $1/Watt. However, the company does not publicly disclose the technical specifications or current selling price of the modules.
• Photovoltaic World production, 1980-2007 (log scale). The line shows the best-fit exponential to the production for the most recent 10 years, indicating a doubling of production every 2 years. Units are peak MW. Image by Geoffrey A. Landis.
• 2008 – New record achieved in solar cell efficiency. Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have set a world record in solar cell efficiency with a photovoltaic device that converts 40.8 percent of the light that hits it into electricity. The inverted metamorphic triple-junction solar cell was designed, fabricated and independently measured at NREL.
• 2010 – BP announces the closing of their photovoltaic plant in Maryland, moving all of their manufacturing work to China.
• 2010 – President Barack Obama orders installation of additional solar panels and a solar hot water heater at the White House.
• 2011 – Fast-growing factories in China push manufacturing costs down to about $1.25 per watt for silicon photovoltaic modules. They flood the world market with modules and put a number of European and North American factories out of business. But installations double worldwide.

Solar technology will continue to hold strong meanwhile being innovated by the young and the old. It’s a magnificent field that encourages thinking, creativity, and impact toward the environment — let the minds never stop!