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Quantum Dots for Solar Power
Jamais Cascio, 24 May 05

Solar photovoltaic generation of electricity has a big problem: with currently-available technology, it's not terribly efficient. I mean that literally; the "solar constant" is ~1.35 kilowatts of power per square meter, but most off-the-shelf solar panels can only convert about 20-30% of that to electricity. Improvement is clearly possible, and some researchers have figured out ways to boost that efficiency to 50% or more (although some promising developments in flexible, polymer-based photovoltaics are far worse, with only 5-15% efficiency). One of the more interesting approaches involves using selenium "nanocrystals" to boost efficiency to up to 60%. Now researchers at the US Department of Energy's National Renewable Energy Laboratory have pushed that concept to a new potential efficiency peak.

By using lead sulfide as the nanocrystal -- or "quantum dot" -- material, the NREL team claims a potential efficiency of more than 65%. We've noted various worldchanging applications of quantum dots before (for infrared-sensitive polymer photovoltaics with ~30% efficiency, and for high-efficiency reversible thermoelectric materials), and it's clear that nanomaterial and nanofabrication research will be critical for making solar photovoltaic sufficiently efficient for widespread adoption.

As usual, the actual article is behind a subscription wall (and the journal is probably too obscure for most non-university libraries), but Alan at @Monkeysign has an excellent dissection of how the technology works, and what challenges remain before it could conceivably make its way to real-world use. I highly recommend checking out his write-up.

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While billions are spent on sports, space exploration, health problems from environmental pollution from fossil fuels, oil spill cleanups and military actions over oil where is the attention to the answer that would help not only our counry but the entire world. Renewable Energy in the future would provide low cost abundant electric to change the world! Sites that generate electric from renewable sources could create millions of jobs and a secure career with income for retirement and a family legacy.

Posted by: Joseph Rothengast on 24 May 05

What is needed is a fabric which is tough, UV insensitive, and cheap which produces electricity. Such a fabric need not be very efficient at all, just incredibly cheap to make and use. A parasol which functions as a flashlight is long overdue.

There was some interesting work being done with light pipes a few years ago....where light from roof pickups was piped into offices below. The light was superior to florescent lighting, changed a little from time to time as clouds would go over, which helped peoples diurnal rythms. Although the initial cost was double that of conventional lighting installation, the electric bill was much reduced. Because there were no moving parts, it paid for itself within a few months. Wonder why it never caught on?
I installed such a unit in my garage...seems to work fine.....

Posted by: Bill Fedun on 25 May 05

Its interesting to see that the discussion still focusses on efficiency, as measured in kilowatts per square meter, when what is really important is kilowatts per dollar.

In other words, I don't really care if the solar panel is 10% less efficient, as long as its half the price. I'll just cover twice the roof area and still be better off.

I think the solar industry got seriously sidetracked for many years by the search for higher efficiency, rather than cost-savings. Probably (and I'm guessing here) being driven by military and space applications where efficiency is a problem.

So ... lets start hearing about these improvements based on their cost-effectiveness.

- Mitra

Posted by: Mitra Ardron on 25 May 05



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