Solar cells aiming for full spectrum efficiency

New Scientist ^ | 10:15 08 December 02 | Jenny Hogan

[Rain-maker]

Solar cells aiming for full spectrum efficiency

10:15 08 December 02

 

Solar power is set for a boost with the help of a material that can soak up energy from almost all of the Sun's spectrum. It should allow solar cells to jump in efficiency from today's best of 30 percent to 50 percent or higher.

Solar cells use layers of semiconductors to absorb photons of sunlight and convert them into electric current. But each different semiconductor can only use photons at a specific energy - its "bandgap".

Today's best cells have layers of two different semiconductors stacked together to absorb light at different energies but they still only manage to use 30 per cent of the Sun's energy. Theorists have calculated which two bandgaps would give a maximum efficiency of 50 per cent, but until now they have not had the semiconductors to do the job.

 

Cont'd: http://www.newscientist.com/news/news.jsp?id=ns99993145

[Jeff Chandler]

Sounds great, but how much will it cost to produce the cells?

[Free the USA]

http://www.freerepublic.com/perl/bump-list

[Birdwatcher]

The efficiency of solar panels is not the issue. It is the cost to produce them that is the issue. They need to find a solar cell that can be mass-produced cheaply. I look forward to when solar cells are cheap enough to become an alternative to generated power. Then I can run all the lights in the house and not worry about the cost!!

[doug from upland]

Interesting news.

[Birdwatcher]

Did you read in the article how they were constructed by one atomic layer at a time in a prohibitively expensive process? Doesn't sound good right now. When will they become like VCRs and other electronics and drop in price?

[TheErnFormerlyKnownAsBig]

This may make it cost effective to use them here in the Pacific Northwest. Thanks for the story. I've been reading up on this stuff and passive solar as well as wind power lately. A 700 dollar electric bill for 2 months during the witnter will do that to you. And that's after I'd cut our usage by 25% from the year before.

This year it's a space heater for each kids bedroom and our fireplace insert for the living area. Our bedroom in the basement get's heated up for an hour before my wife goes to bed and then that space heater gets turned off. Now our 2 month electric bill is 150 bucks because we haven't turned on the heat at all yet this winter and we've made these other changes.

Next up is compact flourescent bulbs which I think can cut our usage by another 10%.

Anyone intersted in this solar stuff can check out a magazine called Homepower and they have a website as well that they put a few articles from every issue up for free reading.

They have some militant stuff where it concerns energy usage but for the most part its just great info. on altenative means of getting power for you home and cutting back on your energy usage to save money.

[TheErnFormerlyKnownAsBig]

I forgot to add "this may make it cost effective here in the NW when they can manufacture it cheap enough.

[Rain-maker]

Demand will inevitabley dictate production cost. Hopefully the industry will see fit to press this technology past the fossil fuel lobbyists and create a substantial market.

You may have found the key to the universe, but marketing is everything...rainmaker

[Jeff Chandler]

Thanks for the story.

You're welcome, but I didn't post it.

Solar cells are great for remote applications, but they're going to have to get the cost down for them to be practical for general consumer use.

[PeaceBeWithYou]

Ping.

Full spectrum solar cell(InGaN) breakthru with 50-70% efficency possible.

[PeaceBeWithYou]

The band gap of InAlN(Indium Aluminum Nitride) is .7 to 6.2 eV compared to InGaN which is .7 to 3.4 eV, which is described as almost the total solar spectrum.

What is in the spectrum between 3.4 to 6.2 eV?

[Rain-maker]

Convert electron-volts to Joules and set up a corresponding chart for nanometers, looks like the lower eV's are towards the infrared spectrum.

http://www.autobahn.mb.ca/~het/energy/pv_fqa.html

http://www.lbl.gov/Science-Articles/Archive/MSD-full-spectrum-solar-cell.html

1eV = 1.6 x 10-19Joules

[Mr170IQ]

I'm also curious in the maximum flux that these new cells can process. If you can use 50 m^2 of dirt cheap reflective optics to focus sunlight on one sq. meter of solar cells, you can get a 98% reduction in costs.

[PeaceBeWithYou]

Thanks, the conversion to nm was very helpful.