The Birth of a Technology
French scientist Edmund Becquerel in 1839 discovered the photovoltaic effect – that light falling on certain materials can produce electricity. Later physicist, including Albert Einstein, found that tiny photons, or particles of light, could interact with electrons surrounding the nucleus of an atom. That interaction causes a free stream of electrons - the basis of electricity.
Scientists in the 1930s developed a theory for the electrical properties of silicon and other crystalline materials, substances that came to be known as “semi-conductors.” Primitive photovoltaic cells were developed using selenium, but they were very expensive, only one percent efficient, and little more than a scientific curiosity.
Early in 1954, a small team of scientists at Bell Laboratories tried to find a practical way to generate electricity for telephone systems in rural areas not connected to power lines. Using crystalline silicon, they fashioned an enormous solar cell capable of turning six percent of the sunlight that struck it into electricity. Soon the efficiency was raised to eleven percent and scientists realized that the new devices could have practical applications. They had another reason for optimism; the material they were using, silicon, is the world’s second most abundant element, comprising 28 percent of the earth’s crust.
These achievements were greeted with much fanfare amid the technological developments of the 1950s. Solar cells seemed to promise an unlimited supply of electricity and roused considerable excitement. A 1957 article in “Business Week” envisioned an automatically controlled solar car in which “all riders could sit comfortably in the back seat and perhaps watch solar-powered TV.”
It was an unfavorable time, however, to develop a new energy technology. Oil was priced at less than $2 per barrel, and large fossil-fuel power plants were built at a record pace. Moreover, in 1954 construction began on the world’s first commercial nuclear reactor. Nuclear power was envisioned as a source of electricity “too cheap to meter,” and most government energy funds were devoted to that technology.
Photovoltaic researchers also faced an unsettling economic reality. Silicon cells developed in the 1950s were extremely expensive, with costs as high as $600 per watt (compared to $5 or $6 today). Funding for research to reduce the cost was not available in an era with falling electricity prices and minimal concerns about the environment.
The space program rescued photovoltaics from the technological scrap heap. American scientists in the late 1950s went searching for a lightweight, long-lasting power source for satellites. Photovoltaic cells, which could take advantage of the continuous sunlight of space, were their choice. In 1958 just four years after the Bell laboratory breakthrough, silicon solar cells were boosted into orbit aboard Vangard I, the second U.S. Satellite.
With the help of large contracts from the National Aeronautics (NASA) four U.S. commercial companies enter the photovoltaics business and by the late 1960’s were producing hundreds of thousands of solar cells a year. Amid the heady competition of the post-sputnik space race, the Soviet Union began equipping its satellites with photovoltaics as well. Today, solar cells power virtually all satellites.
Achievements in photovoltaic cell research during the peak years of the space program included a major increase in efficiency and reduction in cost of more than 400 percent. However, the space-related PV market leveled-off and photovoltaic cell production declined.
In 1973, America was jolted by its first oil crisis – gasoline prices soared and interest in alternative fuels was awakened. Beginning in 1975, the U.S. government funded a steadily growing research and development program aimed at making photovoltaics economical for terrestrial use. Japan and European countries followed suit. Perhaps a dozen private companies entered the solar cell research or production business.
Since the 1970s, the overall market for photovoltaics has increased more than ten-fold. In the same period, the cost of PV modules has dropped from about $50 per watt to $5 or $6 per watt. Production has increased to more than 250 times the highest level during the peak years of the space program, and can barely keep up with demand.