Harry Atwater, a professor from Caltech, says the way to make solar cells that can compete with fossil fuels is to make them thin and flexible. He is not the first to sing the praises of flexible solar cells, but people usually point to their potential applications on tents or backpacks, where they won’t do much to reduce carbon emissions or fossil fuel use. Atwater likes them for their potential to reduce shipping and installation costs.
Unlike today’s rigid, class encapsulated solar panels, flexible solar panels don’t need to be protected by rigid frames for shipping, so they take up much less space, reducing shipping costs. There also lighter, which makes them easier to install. Speaking at the EmTech 10 conference at MIT today, Atwater proposed another way to reduce installation costs: he suggess using farm equipment fitted with laser levels to quickly install large fields of flexible solar panels, laying them out the way plastic sheeting is laid out in some farming today.
The thing that’s held back flexible solar cells so far is that they typically are not very efficient compared to conventional crystalline silicon solar cells. That means you need more of them, which, of course, increases costs. At the conference, Atwater showed off a couple of ways to use high-efficiency solar cell materials in flexible cells. One involved depositing gallium arsenide on a rigid surface, then peeling it off to make a flexible solar cell. The other involves growing crystalline silicon in the form of arrays of wires embedded in polymers. He dropped a sample of the latter material on the stage to demonstrate its resilience. The best of these solar cells made in the lab have achieved over 17% efficiency, he says–that’s competitive with today’s solar cells. (When he makes them over a large area, the efficiency is less than half that, but he thinks this can be improved).
One question is how durable these solar cells prove to be. Today’s solar panels, which are encased in glass, have been proven to last for decades. It will take some long-term testing to show that these flimsy-looking pieces of plastic can last just as long.
Atwater predicts that the cost of making and installing these solar cells can be less than a dollar a watt, low enough to compete generally with fossil fuels. (Solar panels already compete with fossil fuels in some situations in sunny locations.) He says he’s “in the process of commercializing” the technology. He’s realistic about how long it could take to work its way to market but says it’s reasonable to think the technology could allow solar to provide a significant amount (14 percent) of the United States’s electricity supply by 2030.
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