Happy 60th anniversary to the modern solar cell

GreenTech Media

Calvin Fuller, Daryl Chapin, and Gerald Pearson, the principal discoverers of the silicon solar cell. picture credit: ATT Bell Labs

The pioneering engineers of the modern solar cell gathered in person and in spirit this week in Palo Alto, California, to celebrate the 60th anniversary of their invention. Little did they know the impact their discovery would be having on utilities in 2014.

In a volatile, $100 billion, gigawatt-scale global solar industry that’s growing bigger every year, there’s not a lot of time for looking in the rearview mirror — but we’ll take some time to do that here.

John Perlin, author of Let It Shine: The 6,000-Year Story of Solar Energy and the event’s moderator, explained in an email, “The silicon solar cell project got its start in early 1953 when Daryl Chapin began working on the problem of providing small amounts of intermittent power for remote, humid locations where dry cell batteries would degrade rapidly.” Chapin chose to experiment with solar cells made from selenium, a material that had yielded very low efficiencies.

Perlin continues, “At the same time, Gerald Pearson, an experimental physicist, was experimenting with a new silicon semiconductor material developed by Calvin Fuller, a chemist. Pearson found that the silicon was six times as efficient as was the selenium. […] So began the Bell Solar Battery Project in the spring of 1953.”

“By April 1954, the Bell trio had ratcheted up the efficiency to 6 percent [and the cell was] ready for public display.”

Sadly, Chapin, Fuller and Pearson are no longer with us.

At the time, The New York Times hailed the invention “as the beginning of a new era, leading eventually 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.”

Dr. Mort Prince, the last living participant in the Bell Labs PV invention, was one of the honored guests on Friday night in Palo Alto.

Prince spoke of “strangely” getting involved in the Bell Labs project by being called over by Pearson to witness the performance of one of the new Bell Labs cells. “The ammeter swung widely to the right,” Prince recalled.

These cells were an arsenic-doped n-type silicon with a boron-doped emitter with contacts on the back — history as the future, suggests Perlin.

Prince acknowledged the occasional contribution of good luck in an invention like this.

He went on to lead the manufacturing of the solar cells used in the Vanguard space satellite in the 1950s and later headed the PV program under President Carter.

Also on hand was Eugene Ralph, who designed the Vanguard satellite solar array, and helped light the fuse on the commercialization of solar cells with a real application: spacecraft.

Mr. Ralph said that his team was making “cells to the Bell Labs patent,” but “basically we were making toys. We didn’t have a power market.” There were some efforts to mount PV cells on Motorola tube radios.

That changed at the dawn of the space race.

Mr. Ralph said that the Vanguard I satellite, launched in 1958, was originally designed to be powered solely by battery, as had all previous satellites. But the batteries could not keep the satellite going for the desired lifespan.

“In 1958, I happened to get introduced to Bill Cherry from Signal Corp,” said Ralph. The satellite “needed power to run it and he wondered if the solar cells could do that.” Ralph said that the Bell Labs design was changed and he “developed a different technique.” He put the contacts on top, decreased series resistance with long and narrow cells, and boosted efficiency.

He noted that “Vanguard was very successful,” but they forgot to put a switch on “the power source, so the satellite kept transmitting and they wished they could have turned it off” after it had completed its mission.

“Pretty soon, we convinced the space people that solar energy is the way to go.”

Mr. Ralph and Dr. Prince worked together on the Vanguard cells. Ralph later helped found Spectrolab, which is still a supplier of solar cells to the space industry.

Mr. Ralph went on to recount how he and his colleagues designed modules for terrestrial applications using tempered glass and screen-printed contacts, early innovations that are still in use today.

Also in the audience at the event were solar luminaries Jim Caldwell, the first CEO of ARCO Solar; SunPower founder Dick Swanson; relatives of Bill Yerkes; Eicke Weber, President of Fraunhofer ISE; Dr. David Renne, President of the International Solar Energy Society; Bernadette Del Chiaro, Executive Director of the California Solar Energy Industries Association; and solar expert Chris Eberspacher. The nonprofit Renewables 100 Policy Institute organized the event, and its founders Angelina Galiteva and Diane Moss were present, as were representatives of Trina Solar and JA Solar.

Just before a standing ovation for the two early solar explorers, Dr. Price pointed out the small size of the initial Bell Labs solar effort and then said, “Now it’s an army.”

 

An image from the original patent (number 2,780,765) follows:

Vanguard I satellite:

Some vintage newsreel footage on the Bell Solar Battery, complete with projector sprocket mishaps and stentorian narrator:

Source: GreenTech Media. Reproduced with permission.