New Solar Conversion Process... 60% Efficient

[bik0]

New solar energy conversion process could revamp solar power production

Stanford engineers have figured out how to simultaneously use the light and heat of the sun to generate electricity in a way that could make solar power production more than twice as efficient as existing methods and potentially cheap enough to compete with oil.

Unlike photovoltaic technology currently used in solar panels – which becomes less efficient as the temperature rises – the new process excels at higher temperatures.

Called 'photon enhanced thermionic emission,' or PETE, the process promises to surpass the efficiency of existing photovoltaic and thermal conversion technologies.

"This is really a conceptual breakthrough, a new energy conversion process, not just a new material or a slightly different tweak," said Nick Melosh, an assistant professor of materials science and engineering, who led the research group. "It is actually something fundamentally different about how you can harvest energy."

And the materials needed to build a device to make the process work are cheap and easily available, meaning the power that comes from it will be affordable.

Melosh is an assistant professor of materials science and engineering, and is senior author of a paper describing the tests the researchers conducted. It was published online August 1, in Nature Materials.

"Just demonstrating that the process worked was a big deal," Melosh said. "And we showed this physical mechanism does exist, it works as advertised."

Most photovoltaic cells, such as those used in rooftop solar panels, use the semiconducting material silicon to convert the energy from photons of light to electricity. But the cells can only use a portion of the light spectrum, with the rest just generating heat.

This heat from unused sunlight and inefficiencies in the cells themselves account for a loss of more than 50 percent of the initial solar energy reaching the cell.

If this wasted heat energy could somehow be harvested, solar cells could be much more efficient. The problem has been that high temperatures are necessary to power heat-based conversion systems, yet solar cell efficiency rapidly decreases at higher temperatures.

Until now, no one had come up with a way to wed thermal and solar cell conversion technologies.

"The PETE process could really give the feasibility of solar power a big boost," Melosh said. "Even if we don't achieve perfect efficiency, let's say we give a 10 percent boost to the efficiency of solar conversion, going from 20 percent efficiency to 30 percent, that is still a 50 percent increase overall."

And that is still a big enough increase that it could make solar energy competitive with oil.


http://www.eurekalert.org/pub_releases/2010-08/su-nse080210.php

[ixion]

1. Harvesting heat from the sun...

it's about time.

[thetonka]

2. Solar is already a viable solution

People are hung up on the efficiencies and price of solar panels and equipment from 5+ years ago. The cost and efficiency have dramatically changed in the last 5 years. Advances like this only make it better.

[txlibdem]

4. Actually, efficiency is the last thing you should worry about

Increased efficiency will allow you to get more electrical power out of each square foot of panel. But if you have a big enough roof area you never need to even think about the efficiency of your solar panels. The only benefit might come from slightly decreased installation costs but doubling efficiency of your panels will probably only decrease your installation costs by 20%.

It is actually the cost per watt that is the most important thing in solar PV. This innovation will help with that as well, hopefully.

Edited to add: I agree with you that solar is already a viable alternative. I posted in another thread that you could pay off the cost of installing a 2kW solar array in around 4 years if you drive an electric car. That seems to me the best way to think about solar PV on your roof. Unless you're swimming in cash then go all out with the 10kW or higher by all means.

[thetonka]

5. ROI has dropped SIGNIFICANTLY

5 years ago I was looking at systems for a house at around $50K. Today you can get the same size setup for half that. With tax incentives ROI for a grid tied system in Southern California can be less than 2 years. If you add in more capacity for an EV and drive a lot the payback can be really quick, especially if you have a medium to high MPG vehicle and drive a lot.

I commute in a Prius, and wifey has one too. Would need to get a Plug in conversion to use Solar for that, and the prices just can't be justified for mostly freeway commuting.

In SoCal the biggest savings from Solar is Air Conditioning. My boss built a 4500 Sq Ft house with a significant solar array. He has a lot of electronics, electric instant hot water heater, a pool, and keeps his house at 75 degrees year round. His electric bill is $50 a month.


It does depend on where you live, but here in SoCal solar ROCKS! Hoping to have my setup this year.

[txlibdem]

9. 2 years return on investment?

That's fantastic. I went to the solar calculator from the next reply and found a 17 year ROI for Texas and a 10 year ROI for southern California. Please share how you arrived at the 2 year figure for payback of the solar array.

As to the electric car being powered by solar panels on your roof, that is the best way to achieve fast payback for installing a small solar array. Larger arrays of course would take longer to pay off.

I wonder how you're calculating the time it takes to pay off your solar array. Please share!

[XemaSab]

10. According to the calculator I used

a system here would pay for itself in 15 years and it would cost 32,000. It would also need 500 square feet of roof space, which I'm not sure we could do. (It would have to be on the garage, seeing as there's a big ol' energy-saving TREE on our southern exposure.) :P

http://www.mid.org/rebates/solar/solarEstimator.htm

[thetonka]

6. Here is a good online calculator

http://www.solar-estimate.org

[bik0]

3. It will probably take years to patent the technology and raise venture money to fund their startup

Instead of competing as a startup, hopefully they license the technology to existing solar companies. That would make a bigger impact in a shorter period of time.

[txlibdem]

7. I hope they can bring this to market within the next 10 years or sooner

That these solar cells do not suffer from higher heat as conventional solar panels do is IMO the best thing about them. Lowering the cost per watt is what they need to focus on initially so they can get into the market faster.

In other words, low efficiency is not the main thing stopping most folks from getting solar panels. It is the cost per watt being still far too high that is the major show stopper. Solar panel per watt prices had been dropping steadily up to about 2 or 3 years ago. Then Germany started buying every solar panel that could be made and the price drop stopped in its tracks. Solar PV prices has been flat for the last 2 years.

I am definitely out of the market for anything solar till the price comes down.

[bik0]

8. Patent...

http://www.faqs.org/patents/app/20100139771