THE SOLAR CELL TURNS 60, Part 2
How and when was the photovoltaic effect discovered...
For the 60th anniversary of the silicon solar cell, PV60 – History Becoming the Future, is being organized by the Renewables 100 Policy Institute and co-sponsored by the City of Palo Alto on April 18, 2014. To join the celebration, NewEnergyNews will run, on April 18 and 19, eight questions and answers about the silicon solar cell’s history from John Perlin, the author of Let It Shine: The 6,000 Year Story Of Solar Energy.
2-How and when was the photovoltaic effect discovered in a solar cell?
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response ruled out the possibility that heat from the candle’s flame was the cause, because when heat is applied or withdrawn in thermoelectric experiments, the needle always rises or drops slowly.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.” click here for more