The technology that’s surprised almost everyone is conventional crystalline silicon. A few years ago, silicon solar panels cost $4 per watt, and Martin Green, professor at the University of New South Wales and one of the leading silicon solar panel researchers, declared that they’d never go below $1 a watt. “Now it’s down to something like 50 cents of watt, and there’s talk of hitting 36 cents per watt,” he says.
While small changes to the way solar panels are responsible for much of this price drop – things like being able to print the ultra-fine wires used to connect the cells in a panel and cells that can absorb sunlight from both the front and back – the biggest change is going to be the introduction of different semiconductors in the cells themselves:
Even longer-term, Green is betting on silicon, aiming to take advantage of the huge reductions in cost already seen with the technology. He hopes to greatly increase the efficiency of silicon solar panels by combining silicon with one or two other semiconductors, each selected to efficiently convert a part of the solar spectrum that silicon doesn’t convert efficiently. Adding one semiconductor could boost efficiencies from the 20 to 25 percent range to around 40 percent. Adding another could make efficiencies as high as 50 percent feasible, which would cut in half the number of solar panels needed for a given installation.