New Coating Radiates Heat to Keep Solar Cells Cool—and More Efficient

Illustration for article titled New Coating Radiates Heat to Keep Solar Cells Cool—and More Efficient

Solar cells suffer a strange problem: the hotter they get as the sun pours down on them, the less efficient they become at converting light into electricity. But now a team of Stanford researchers have developed a new transparent coating that can help them keep a little cooler—and more efficient.

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The new coating is based on a simple idea: When you step outside, the top of your head radiates (at least a little) heat up into the universe as infrared light. The new coating, described in Proceedings of the National Academy of Sciences, uses the same idea to help solar cells quickly shed heat.

The material is a relatively simple film of thin, patterned silica, which can be laid down on top of a normal solar cell. The sheet is transparent to the visible light which drives solar cells, but it absorbs — and crucially emits — thermal radiation in the form of infrared rays. So essentially it sucks heat from the solar cell and pumps it out into the atmosphere, helping lower the temperature of the device. The technology is based on a previous coating developed by the group, which both reflected sunlight and radiated heat.

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In tests performed atop a Stanford roof, the team showed that the film allowed visible light to pass through but reduced the temperature of the cell beneath by up to 23 degrees Fahrenheit. For a fairly normal crystalline silicon solar cell with 20 percent efficiency, the researchers claim that sort of temperature reduction could equate to an increase in the absolute cell efficiency by over 1 percent — not to be sniffed at if the film can be made affordably.

No wonder, then, that the team is now working to develop lithography techniques that can be used to generate the film at a commercial scale.

[PNAS via PhysOrg]

Image by Michael Shealy under Creative Commons license.

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DISCUSSION

cochese4k120fps
Cochese: 4k120fps

It all makes sense now. On day four of my current cross country bicycle tour, my 14 watt solar panel stopped charging my phone and backup battery pack. But it was 98 degrees that day. And humid as hell. The panels were too hot too touch as they were spread across my rear paniers and in full sun. The next day was about ten degrees cooler and partly cloudy and it worked like a champ. It’s now day thirty and aside from a few totally overcast days, it’s worked perfectly.
If anybody is interested in following me across the country, just hit up Facebook.com/thespokemen it’s just my friend and I. We’ve rolled over 2000 miles S far and are currently stealth camping outside of Mapleton, Minnesota, near Minnesota Lake. Just thirty (or less) more days until Seattle!