Simply Layering Solar Cells Could Make Them as Cheap as Natural GasIt's not uncommon to focus on excotic solutions to making solar power more efficient: new materials, complex tracking systems or unusual physical phenomena. But what about just stacking them on top of each other?

Technology Review reports that a startup called Semprius is doing just that, and it reckons it could make solar as cost-effective as natural gas. The idea is simple: just stack different semiconducting materials that collect different frequencies of light on top of each other, allow the light to pass through from one to the next, and collect the energy they all produce at once.

Sounds simple, but it required some thought to get working. Semprius has developed a new way of easily stacking multiple semiconductors on top of each other, a new adhesive to hold them together without affecting their performance, and a way to link up all of their outputs.

And it works! The start-up has already put together two different solar cells which stack four different semiconductors on top of each other. One is 43.9 percent efficient, the other 44.1 percent. Those figures compare amazingly well to the best single-layer solar cells currently available, which achieve about 25 percent. The goal is to up the number of layers to six and increase efficiency to beyond 50 percent.

The catch? Because they use so many layers of semiconductor, they're wildly expensive right now. But mass production should lower the initial costs, and at any rate they could well be outweighed by their stunning efficiency. Technology Review suggests that they could eventually produce electricity at less than five cents per kilowatt-hour—as cheap as natural gas. [Technology Review]

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