6,000 Years of Solar: From Selenium to Silicon and Beyond
“6,000 Years of Solar” is a series about the history of solar energy technology drawn from John Perlin’s new book Let It Shine: The 6,000-Year Story of Solar Energy. The series profiles the fascinating people, from ancient Greece and China to late 19th century New York to today, who have made the present day solar revolution possible.
This article was originally published on The Alternative Energy eMagazine in the April/May 2014 issue.
You say we are coming to the 60th Anniversary of the first practical solar cell. Can you explain?
Yes, sixty years ago on April 25, 1954, scientists at Bell Laboratories presented the first solar cell capable of converting enough sunlight into electricity to produce useful amounts of power, which has sired today’s booming photovoltaic industry. This was one of the most significant breakthroughs ever recorded in the history of solar developments. The New York Times agreed, stating on its front page the next day that the invention of the Bell silicon solar cell marked “the beginning of a new era eventually leading to the realization of one of mankind’s most cherished dreams – the harnessing of the almost limitless energy of the sun for the uses of civilization.”
When did work on solar photovoltaics begin?
In 1872, British engineer Willoughby Smith published a paper on the photo-sensitivity of selenium. The article led English scientists William Grylls Adams and Richard Evans Day to further experiment with the material. In one of these trials they lit a candle an inch away from same bars of selenium that Smith had used. The needle on their measuring device reacted immediately. Screening the selenium from light caused the needle to drop instantaneously. The rapid response ruled out the possibility that heat from the candle’s flame was the cause, because when heat is applied or withdrawn in thermoelectric experiments, the needle always rises or drops slowly. “Hence,” the investigators concluded, “it was clear that a current could be started by the action of light alone.” They wrote that they had discovered a completely new phenomenon – that light had caused a flow of electricity through a solid material. Adams and Day called current produced by light “photoelectric.” Today, we call it “photovoltaic.”
So why didn’t photovoltaics take off in the nineteenth century?
American inventor Charles Fritts did put together selenium modules and placed a test array on a New York rooftop in the mid 1880s. He optimistically predicted that soon his modules would compete on the market place with the new electric power plants established by Thomas Edison. Europe’s Edison, Werner von Siemens, called photovoltaics to be “scientifically of the most far-reaching importance,” and the world’s leading physicist of the nineteenth century, James Clerk Maxwell, called Adams and Day discovery as “a very valuable contribution to science.” But the science of the nineteenth century lacked the wherewithal to explain the direct transformation of light into electricity. The rejection by Adams and Day of a thermal effect producing the electricity from the selenium bars led most to dismiss the discovery as heretical as the science of the day believed that only heat could produce power.
How did the scientific community come to accept photovoltaics as a legitimate area of study?
Einstein’s new understanding of light combined with the late nineteenth-century discovery of the electron uncovered the secret of photovoltaics: light consists of packets of energy, according to the new science, capable of setting electrons into motion whose orderly movement is electricity.
Did scientific acceptance lead to practical developments?
Scientific acceptance led to a flurry of activity in the photovoltaic field. But try as they may, no one could construct a solar cell efficient enough for everyday power needs. As one scientist lamented in 1949, “It must be left to the future whether the discovery of materially more efficient cells will reopen the possibility of harnessing solar energy for useful purposes.”
Can you take us back to the moment of solar’s big breakthrough?
The semiconductor revolution began at Bell Laboratories that started with the discovery of the transistor and took silicon electronics from theory to working device led to the great breakthrough that we are celebrating this year. Serendipitously, Gerald Pearson, a Bell scientist, took one of the first silicon transistors and applied light to it. To his surprise, he recorded an efficiency of almost six times greater than any other solar cell had ever produced. Like Archimedes, he ran down the hall at the lab, shouting to a colleague, Daryl Chapin, who was working with selenium at the time for a remote telephone power project, “Don’t waste another moment on selenium!,” and gave him his piece of doped silicon. So began the Bell Solar Battery project that a year later in 1954 produced the most significant breakthrough in solar history and perhaps, the history of electricity – a solar cell capable of converting enough sunlight directly into electricity for useful purposes.
Why didn’t the silicon solar cell immediately take off?
First, its price was an obstacle. One watt cost $286. Today, a watt is $.70. More importantly, at the moment of the solar breakthrough, the Eisenhower Administration, to counter worldwide anti-nuclear protests that were considered damaging to the U.S. Cold War efforts, initiated the Atoms for Peace program to give nuclear a happy face. Subsidies and funding for nuclear ran into the billions. There was no parallel Solar for Peace program, despite the fact the Bell discovery. Selling the “peaceful atom” as the world’s future energy source had become America’s number one priority and eclipsed any consideration of solar development to meet anything but far-off energy needs. The media jumped on that bandwagon, with the New York Times declaring: "Electricity from the atom will keep industry turning and homes lighted for centuries in the future. And the energy of the sun...will be available after the last atomic fuel is gone."
How did silicon solar cells succeed under such pressure?
After such high expectations, the inventors could not help but wonder, “What to do with our new baby.” Desperate to find commercial applications, solar cells found their way powering novelty items such as toys and transistor radios. Then the space race came. The first two Sputniks went dead after several weeks in space, as they ran on battery power alone. No one could go up and recharge or replace them. For the same reason, fuel-powered engines were ruled out. For any satellite that had to function for more than three weeks or so, solar cells appeared to be the perfect source of power. The first solar-run satellite – the Vanguard - went up in March, 1958. It kept on transmitting data over the next six years. The success of solar on the Vanguard led engineers and scientists working with satellites to accept the solar cell as one of the critically important devices in the space program, since they provided the only practical power source for long-term missions. The urgent demand for solar cells above the earth opened an unexpectedly large and lucrative business for manufacturing them. Locked into the space race with the Russians, the American government poured millions into solar cell research and development. As solar-cell pioneer contends, “The onset of the Space Age was the salvation of the solar-cell industry.”
So how did solar get from space to earth?
While the military and NASA supported solar, the rest of the American government continued to ignore suggestions by experts to aggressively fund photovoltaics for applications on earth. Slowly, demand for electricity far away from the grid began to build up interest for terrestrial photovoltaics. Ironically, the first large customers were the oil and gas industry, which needed power for warning lights and horns on offshore rigs
because they had no electrical source nearby.
By 1985, solar became the fuel of choice for remote telecommunication networks. People distant from any power source began purchasing solar modules to run lights and appliances. By the 1980s, 50% of those living in outlying islands in the French Polynesia powered their homes with the sun.
In that same time frame, the Reagan Administration declared war against all solar technologies including pv. As a consequence, interest in the use of the American-discovered solar cell migrated first to Japan in the 1990s, where the government oversaw the placement of photovoltaics on thousands of rooftops.
But it was in Germany at the turn of the millennium when pv really took off. A new law called the Renewable Energy Sources Act (commonly known as the German feed-in tariff) provided decent remuneration for all electricity generated by qualifying renewable sources, along with guaranteed interconnection to the grid and other certainties that spurred mass investment in renewable power installations. This, combined with a glut in global silicon production and the Chinese government’s financial backing of large-scale pv manufacturing plants, led the price of silicon solar modules to plummet. The cumulative installed photovoltaics grew from less than 1 billion watts in 2000 to more than 100 billion watts today. That’s a pretty exciting 60th birthday present for practical photovoltaics!
Are there any plans to celebrate the 60th anniversary?
Yes! On April 18, 2014, the Renewables 100 Policy Institute is organizing a birthday bash in Palo Alto at the Lucie Stern Community Center, where people will actually get to meet and pay tribute to some of the great pioneers from the Bell and Vanguard era. Among the distinguished people present will be Dr. Mort Prince, the last surviving member of the original Bell Laboratories team, who was there during the big solar breakthrough and built the 1954 demonstration arrays. He went on to oversee the manufacturing of the Vanguard solar cells and later to head the U.S. photovoltaics program under President Carter. Also there will be Eugene Ralph, who worked with Dr. Prince and designed the Vanguard arrays. He went on to co-found Spectrolab. The two of them can take a lot of credit for launching the solar industry. I will moderate a chat with them about their memories of the amazing piece of history in which they participated.
People will also get to see an exhibit of rare artifacts from the dawn of the solar era, including original Bell Laboratories modules, archival photos and films, and formerly top secret documents that show another layer of the fascinating struggles and triumphs of solar technology. And attendees can get a signed copy of my latest book: Let It Shine: The 6000-Year Story of Solar Energy.
Additionally honored at the event will be the City of Palo Alto, which will receive the History Becoming the Future Award for recently being among the first cities to reach the goal of 100% carbon neutral electricity community wide, achieved entirely with solar and other renewable installations and credits.
This is an event that any solar enthusiast should not miss. You can learn more by visiting www.pv60.org or contacting d.moss@renewables100.org.
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John Perlin is an analyst in the physics department of the University of California, Santa Barbara and is a former CEC Staffer. He oversees solar installations at the university, and he writes, speaks, and lectures about solar energy.