John Perlin*, the author of From Space to Earth – The Story of Solar Electricity, provides here a short summary of the evolution of photovoltaics - Photovoltaics refers to the direct conversion of sunlight to electricity using semiconductor materials such as silicon.
Click here to purchase the book**
1876 – PHOTOELECTRIC DREAMS
|William Grylls Adams, who, with his student, Richard Evans Day, discovered in 1876 that a solid material – selenium – produced electricity when exposed to light. Today, we refer to electricity produced directly from light as the photovoltaic effect.|
When William Grylls Adams and his student, Richard Evans Day, discovered that an electrical current could be started in selenium solely by exposing it to light, they felt confident that they had discovered something completely new. Werner von Siemens, a contemporary whose reputation in the field of electricity ranked him alongside Thomas Edison, called the discovery “scientifically of the most far-reaching importance.” This pioneering work portended quantum mechanics long before most chemists and physicist had accepted the reality of atoms. 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 without moving parts.
1953 – THE DREAM BECOMES REAL
Gerald Pearson, Daryl Chapin, and Calvin Fuller (left-to-right), the principle discoverers of the silicon solar cell, the first material to directly convert enough sunlight into electricity to run electrical devices, measure electrical energy produced by one of their first cells under a lamp.
(with permission from ATT Bell Labs)
In spring 1953, while researching silicon for its possible applications in electronics, Gerald Pearson, an empirical physicist at Bell Laboratories, inadvertently made a solar cell that was far more efficient than solar cells made from selenium. Two other Bell scientists – Daryl Chapin and Calvin Fuller – refined Pearson’s discovery came up with the first solar cell capable of converting enough of the sun’s energy into power to run everyday electrical equipment. Reporting the Bell discovery, The New York Times praised it as “the beginning of a new era, leading eventually to the realization of harnessing the almost limitless energy of the sun for the uses of civilization.
1956 Searching for Applications
During the first years after the discovery of the silicon solar cell, its prohibitive cost kept it out of the electrical power market. Desperate to find commercial outlets for solar cells, novelty items such as toys and radios run by solar cells were manufactured and sold as this advertisement illustrates.
Although technical progress of silicon solar cells continued at breakneck speed – doubling their efficiency in eighteen months – commercial success eluded the Bell solar cell. A one-watt cell cost almost $300 per watt in 1956 while a commercial power plant cost 50 cents a watt to build at that time. The only demand for silicon solar cells came from radio and toy manufacturers to power miniature ships in wading pools, propellers of model DC-4′s, and beach radios. With solar cells running only playthings, Daryl Chapin could not help but wonder, “What to do with our new baby?”
Late 1950s – Saved by the Space Race
|The late Dr. Hans Ziegler, the chief advocate for powering satellites with silicon solar cells|
While efforts to commercialize the silicon solar cell faltered, the Army and Air Force saw the device as the ideal power source for a top-secret project – earth-orbiting satellites. But when the Navy was awarded the task of launching America’s first satellite, it rejected solar cells as an untried technology and decided to use chemical batteries as the power source for its Vanguard satellite. The late Dr. Hans Ziegler, probably the world’s foremost expert in satellite instrumentation in the late 1950s, strongly differed with the Navy. He argued that conventional batteries would run out of power in days, silencing millions of dollar worth of electronic equipmen