Peel-Off Solar Cells Coming Soon

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Solar is about to get crazy thin, thanks to a startup that has a way to make peel-off solar cells.

First you have to forget everything you know about thin-film solar cells, the kind where semiconductor material is literally printed onto a thin plastic or glass. Sure, it's cheaper to manufacture than the standard, albeit brittle, silicon wafers, but it's not as efficient at converting sunlight into electricity.  

Researchers at Austin-based startup AstroWatt took a closer look at the process for making standard solar cells and noticed that slicing a block of crystalline silicon into thin wafers usually generates as much unusable dust as it does wafers. That's some serious and costly waste.

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So, AstroWatt proposed a new process that reduces the waste while producing superthin solar cells. They still started with a large block of crystalline silicon, but instead of slicing it up, they coated the top with metal. Next, they heated the block and then used a wedge to peel off a thin 25-micrometer layer of silicon joined to the metal. As Technology Review's Kevin Bullis explained recently, this process keeps the silicon from shattering even though the result is a super thin wafer.

AstroWatt says this new process can squeeze five or more solar cell wafers out of the same block of silicon that, with traditional, dusty methods, can only yield three. Another advantage: leftover silicon will be in chunks instead of dust so it can be reheated into larger pieces to get used. The startup says the overall result is a cheaper per-watt cost.

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Just to be clear, these aren't peel-off solar cells for consumers to plaster all over their houses or vehicles like stickers — although that seems like a logical step in photovoltaic technology. After all, Notre Dame science professor Prashant Kamat recently led the development of a solar paint-like substance called "Sun-Believable."

Instead, the AstroWatt technique is really about making traditional solar cells using an innovative process that's cheaper and less wasteful. The more affordable and streamlined PV technology gets, the easier it will be to stick it everywhere.

Photo: A five-inch wafer of extremely thin crystalline silicon. Credit: AstroWatt 

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