The future of solar cells is bright

High oil prices and the BP spill are just two real reminders of how energy dependent we truly are, but tomorrow's solar technology promises cleaner power at lower costs.
Written by Boonsri Dickinson, Contributing Editor

With every passing second, the sun releases five million tons of energy. And researchers are figuring out ways to capture more of that precious power.

However, solar technology is far from perfect, and the technology used today is still pretty inefficient.

Fortunately, several intrepid researchers have been working hard to crack the case of a more efficient solar cell. The scientists, no doubt, have been creative, as they look into pokeberries, cow brain protein, silicon ink-based solar cells, giant gravel batteries and solar fuels as possible solutions.

The problem? Photovoltaic cells are inefficient. At best, the cells are only 20 percent efficient at converting heat directly from sunlight.

But some research groups around the nation are beginning to change that.

SmartPlanet correspondent Sumi Das visited Stanford University to find out how one scientist is squeezing more energy out of the sun.

First, watch the video above.

Getting more energy from the sun

Das spoke to Stanford engineer Nick Melosh about a new solar conversion process called Photon Enhanced Thermionic Emission, or PETE. Melosh's method can up the efficiency to 30 percent.

"It really uses the energy coming from the sun twice. So the idea is the sun comes in, you absorb it and then you use that just like a photovoltaic would and so you get some electricity out directly, but all the waste heat that is generated now goes to a thermal conversion system where it tries to convert some of that energy again," Melosh said.

PETE works best at high temperatures, so it won't be the kind of technology that ends up on your roof. However, the technology could be used in large scale power generation projects such as solar farms in the desert.

"We think that with a reasonable cost of a few thousand dollars per wafer and then integrating with existing systems you could get in-line with the same costs for natural gas, electrical production," Melosh said.

Windows do the trick

British scientists are turning to windows to get off-the-grid. Oxford PV developed a way of printing organic solar cells directly onto glass, which could easily be used in new housing and business construction projects.

The company uses a dye-sensitive cell mimics photosynthesis to generate electricity. Now that's one way to incorporate solar energy into buildings without the hassle of adding solar panels.

And at the University of South Florida, researchers are moving beyond solar installations and putting all bets on spray cans. The scientists developed a coating that can be sprayed onto surfaces to create solar panels.

These solar panels can generate power from artificial light.

Solar shingles on your roof

Imagine if solar panels didn't look like panels at all but rather looked more like regular, old fashion shingles.

Dow Chemical Company’s Powerhouse has that covered: solar shingles.

The product integrates low-cost thin-film photovoltaic cells into roofing shingles. That way, the shingles can be installed just like traditional asphalt shingles would. So it does the job of a regular asphalt shingle, but it can also generate electricity.

Each shingle has an electrical circuitry and is connected by wireless plug-style connectors. It is made with a flexible thin-film copper indium gallium diselenide PV solar cell. It’s apparently supposed to lower solar PV installation costs, mainly because the person installing it doesn’t need special knowledge or extra training to do so.

Solar cells from fly eyes

Some of the best ideas for solar cells comes from nature.

Akhlesh Lakhtakia has a good story worth hearing. While Lakhtakia was growing up in India, he tried to kill flies with his hands.

He blamed his inability to catch the flies on the fact that he had small hands. But he knew that the flies could see him much better than he could see them. Flies can see your hand coming. Their big eyes are positioned on their head, in a way that let’s them see 270 degrees around them. Without a fly swatter, Lakhtakia didn’t stand a chance.

“I thought about those things back then,” he says.

He still does. A few years ago, when Lakhtakia was in his lab at Penn State University, he was trying to figure out how to decorate a solar cell that captures light from the side to increase the efficiency of the cell. He thought, well flies do it.

“So we chose the eyes of flies,” Lakhtakia said. The engineering professor has created the first industrial way to pattern solar cells using the eyes of flies. “I’m not saying this will happen tomorrow, but it’s in the realm of industrial possibility,” he said.

Bioreplication is less than 10 years old — no one has figured out a way to automate the process. For now, it’s done the hard by — by hand.

“You could make one copy of it from the original. Doing that on an industrial scale would deplete the natural source. Even if people don’t like flies, it’s still not a good idea [to use a fly for every copy],” Lakhtakia said.

We have to work on automating the process, he says. But this will take us a few years.

The future of...solar cells

But like Dow, companies aren't waiting on the technology to mature. Companies have already begun rolling out with solar panels that are just good enough to get the job done.

As the price of solar cells continues to drop, it's hardly surprising that solar panels are cropping up on more residential rooftops - and even being used to power entire communities.

For instance, Southern California Edison will now buy electricity from solar power plants, hoping that the agreement will help the state meet its goals for renewable energy. According to SF Gate:

"We've gone from something that powers call boxes on the side of the road to something that powers a house to something that generates power for thousands of homes," said Howard Wenger, president of SunPower's utility and power plants business group.

Beyond California, other regions of the world seem pretty hopeful about the promise of solar technology.

One such effort, for example: The Desertec Industrial Initiative, an ambitious plan to build concentrated solar power (CSP) plants in the Sahara desert to satisfy Europe’s demand for power. For a region that’s been hit hard by a drawn-out recession, it may fuel a revival. The $400 billion project is being funded by 10 major companies, including Siemens and Deutsche Bank.

But there are technical and funding issues that need to be tackled before solar power ever sees the light as a dependable, renewable energy source.

"Someone has to come up with a way. The sun is our absolute most abundant source of energy. It’s just a matter of harnessing it. Some company, or many companies, are going to do a better and better job of that. We hope to be one of those companies," HyperSolar CEO Tim Young told SmartPlanet's Andrew Nusca.

"The reason solar is surviving right now, whether Germany or the U.S., is the subsidies. But if the economy goes in the direction it’s going, and the subsidies go away, current manufacturing is going to die, real fast, unless someone comes up with a disruptive technology," Young added.

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