Brief History of Solar PV Technologies (U.S.)
Sunlight is the world’s largest energy source and for thousands of years, it has been human civilizations chief source of light and heat. Today, solar energy technologies are being developed and refined to more effectively use the sun’s power for producing electricity (photovoltaics), as well as steam and hot water for industrial processes (solar thermal technologies). In less than an hour, the U.S. receives more energy in the form of sunlight than it does from the fossil fuels it burns in a year.
The roots of PV energy grew out of experiments done over 150 years ago by the French physicist Antoine-Cesar Becquerel in 1839. He observed that he could produce an electric current by shining light on an electrolytic cell composed on an electrolyte and two electrodes. The German scientist Heinrich Hertz and other observed the PV effect - the conversion of light into electricity - in solids during the 1870’s, and the first primitive PV cells were built in the 1800s, with about 1-2 percent efficiencies. In 1954, Bell Labs in the U.S. introduced the first solar photovoltaic device that produced a useful amount of electricity, and by the late 1950s solar cells were being used in small-scale scientific and commercial applications, especially for the U.S. space program.
Photovoltaics, or PV for short, is a technology in which light is converted into electricity using photovoltaic modules that have no moving parts, operate quietly without emissions, and are capable on long-term use with minimal maintenance. Crystalline silicon, the same material commonly used by the semiconductor industry, is the material used in 94 % of all PV modules today. PV modules generate direct current (DC) electricity. For residential use, the current is fed through an inverter to produce alternating current (AC) that can be used to power the home’s appliances. The main barrier to widespread use of this technology is the initial high equipment cost. PV technology was been advancing over the last few decades and prices have steadily declined. In 1990, worldwide PV sales reached 48 MW, including use in everything from pocket calculators to communications systems. In 2007, world wide solar cell production reached a consolidated figure of 3,435 MW (Solarbuzz).
Thanks to national R&D programs and major capital investments in manufacturing, the price of solar PV has dropped considerably and now costs 1/10th what it did only 20 years ago.
The Department of Energy’s Energy Efficiency and Renewable Energy Program’s web site has developed a History of Solar timeline through 2002 that notes major historical developments in the history of solar PV technologies.