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Energy timelines


A photovoltaic cell, also called a PV or solar cell, is a device that converts light (radiant) energy directly into electrical energy. PV cells are usually made from silicon. The first PV cells were very inefficient, converting less than 1% of radiant energy into electricity. Today, some solar cells have a 40% conversion rate.

  • Wilhelm Hallwachs (German) discovered that a combination of copper and cuprous oxide was sensitive to light.
  • Albert Einstein published a paper on the photoelectric effect. He would win 1921 Nobel Prize in Physics for these theories.
  • Inventors at Bell Labs (Daryl Chapin, Calvin Fuller, and Gerald Pearson) developed a more efficient PV cell (6%) made from silicon. This was the first solar cell capable of generating enough power from the sun to run everyday electrical equipment.

  • Western Electric began to sell commercial licenses for silicon photovoltaic technologies. Early successful products included PV-powered dollar bill changers and devices that decoded computer punch cards and tape.

  • Federal support for photovoltaic technology was initially tied to the space program to provide power for the Vanguard satellite.
  • Spurred by the oil embargo, interest in space applications of photovoltaics grew.
  • By the late 1970s, a program for the development of distributed photovoltaics was established by the U.S. Government at the Massachusetts Institute of Technology, focusing on design and demonstration issues for the buildings sector.
  • The Energy Tax Act of 1978 established a 10-percent investment tax credit for photovoltaic applications.
  • The Solar Photovoltaic Energy, Research, Development and Demonstration Act of 1978committed $1.2 billion, over 10 years, to improve photovoltaic production levels, reduce costs, and stimulate private sector purchases.
  • Photovoltaic energy commercialization program accelerated the procurement and installation of photovoltaic systems in Federal facilities.
  • The Carlisle house (Massachusetts) was completed with participation from MIT, DOE, and Solar Design Associates. It featured the first building-integrated photovoltaic system, passive solar heating and cooling, superinsulation, internal thermal mass, earth-sheltering, daylighting, a roof-integrated solar thermal system, and a 7.5-peak-watt photovoltaic array of polycrystalline modules from Solarex.
  • The Crude Oil Windfall Profit Tax Act of 1980 was enacted, raising the residential tax credit to 40% of the first $10,000 for photovoltaic applications, and the business tax credit to 15%. The Act also extended the credit to the end of 1981.
  • Boeing and Kodak fabricated the first thin-film photovoltaic cells with efficiencies greater than 10%.
  • The 6-megawatt Carissa Plains plant was added to Southern California Edison’s system. The project was later dismantled.
  • The Renewable Energy and Energy Efficiency Technology Competitiveness Act of 1989 sought to improve the operational reliability of photovoltaic modules, increase module efficiencies, decrease direct manufacturing costs, and improve electric power production costs.
  • PV for Utility Scale Applications (PVUSA), a national public-private partnership program, was created to assess and demonstrate the viability of utility-scale photovoltaic electric generating systems. PVUSA participants include the DOE and other agencies, the Electric Power Research Institute, the California Energy Commission, and Pacific Gas & Electric (PG&E) and eight other utilities.
  • Siemens A.G. of Munich, West Germany, acquired California-based ARCO Solar, the world’s largest photovoltaic company.
  • The PV Manufacturing Technology (PVMaT) project began. A government-industry research and development partnership between DOE and members of the U.S. photovoltaic industry was designed to improve manufacturing processes, accelerate manufacturing cost reductions for photovoltaic modules, improve commercial product performance, and lay the groundwork for a substantial scale-up of manufacturing capacity.
  • The University of South Florida fabricated a 15.89% efficient thin-film cell, breaking the 15% barrier for the first time
  • Pacific Gas and Electric completed the installation of the first grid-supported photovoltaic system in Kerman, California. The 500-kilowatt system was the first effort aimed at “distributed power,” whereby a relatively small amount of power is carefully matched to a specific load and is produced near the point of consumption.
  • New world-record efficiencies in polycrystalline thin film and in single-crystal devices, approaching 16% and 30%, respectively, were achieved in 1993.
  • The National Renewable Energy Laboratory (NREL) developed a solar cell made of gallium indium phosphide and gallium arsenide; it was the first one of its kind to exceed 30% conversion efficiency.
  • An Amoco-Enron joint venture announced its intention to use amorphous silicon modules for utility-scale photovoltaic applications.
  • Subhendu Guha, a scientist noted for his pioneer work in amorphous silicon, led the invention of flexible solar shingles, a roofing material and state-of-the-art technology for converting sunlight into electricity on buildings.
  • Construction was completed on Four Times Square in New York, New York. The office building had more energy-efficient features than any other commercial skyscraper and included building-integrated photovoltaic panels on the 37th to 43rd floors, on the south- and west-facing facades, to produce part of electricity needed for the building.
  • Spectrolab, Inc., and the NREL develop a 32.3% efficient solar cell. The high efficiency resulted from combining three layers of photovoltaic materials into a single cell.
  • Researchers at the NREL developed a record-breaking prototype solar cell that measured 18.8% efficiency, topping the previous record for thin-film cells by more than 1%. Worldwide, installed photovoltaic capacity reached 1,000 megawatts.
  • First Solar began production at the Perrysburg, Ohio, photovoltaic manufacturing plant. Each year, it could produce enough solar panels to generate 100 megawatts of power.
  • Astronauts began installing solar panels at the International Space Station, on the largest solar power array deployed in space. Each "wing" of the array consisted of 32,800 solar cells.
  • BP and BP Solar announced the first BP Connect gasoline retail and convenience store in the United States. The Indianapolis, Indiana, service station features a solar-electric canopy. The canopy contains translucent photovoltaic modules made of thin-film silicon integrated into glass.
  • Boeing Spectrolab and the NREL created the High-Efficiency Metamorphic Multijunction Concentrator Solar Cell, or HEMM solar cell, which achieved the highest efficiency level of any photovoltaic device to date. The HEMM solar cell broke the 40% conversion efficiency barrier, making it twice as efficient as a typical silicon cell.

Last Revised: July 2008
Sources: U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar History Timeline: 1900's, January 2008

U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, "Solar Cells," October 21, 2007
Big Frog Mountain, Alternative Energy Sources, Intro to History of Solar Electric Power, January 2008