When the Utah native arrived at Sandia in 2004, Nielson was one of the world's leading Greg Nielson
Sandia National Laboratoriesresearchers of optical microelectro-mechanical systems—technology that uses light to drive tiny machines. It was a wrong number in 2005 that led him into solar power. One of Sandia's leading solar researchers, Vipin Gupta, accidentally called Nielson's office. Soon, the two scientists started chatting. "I found out that silicon materials account for something like 40 to 50 percent of the total costs of most solar panels," Nielson says. By using microfabrication techniques borrowed from the electronics industry, he discovered that he could make solar cells that use 100 times less silicon to produce the same amount of electricity.