Sunshine is free, so can photovoltaics be cheap?

: Image via CrunchBase

Here’s how to make a solar cell from silicon: take one solid block of doped silicon, saw it into thin wafers, layer said semiconductors beneath a panel of transparent glass, connect them to a metal electrode that can channel away the electrons knocked loose by incoming photons and turn it into a photovoltaic device. That process has at least two flaws: such silicon is expensive, contributing more than half to the final price of a solar photovoltaic, and sawing it turns as much as half of that silicon into wasted grit.*

As a result, solar costs as much as $4 per watt by the time it’s installed on your roof or in a large-scale power plant, says Arun Majumdar, the first director of the new Advanced Research Projects Agency for Energy, or ARPA-E. “If you can reduce that to $1.50 per watt it can enable scaling,” or widespread adoption of the clean, renewable electricity source, he told ScientificAmerican.com at last week’s ARPA-E summit.

And a company called 1366 Technologies may have found a way to do just that by growing a nearly pure wafer directly from melted silicon rather than forming an ingot that is then sawed.

That may make silicon photovoltaics, which are the most efficient currently at turning sunlight into electricity, as cheap as thin-film solar cells, whose advantage is cost but which are not as good at creating electric current. In fact, rapidly decreasing cost for solar power means some experts expect such distributed electricity generation to cost the same or less than electricity from today’s grid by as soon as 2015.

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