Towards a 50% Efficient Solar Cell 129
necro81 writes "IEEE Spectrum magazine has a feature article describing DARPA-funded work towards developing a solar cell that's 50% efficient, for a finished module that's 40% efficient — suitable for charging a soldier's gadgets in the field. Conventional silicon and thin-film PV tech can hit cell efficiencies of upwards of 20%, with finished modules hovering in the teens. Triple-junction cells can top 40%, but are expensive to produce and not practical in most applications. Current work by the Very High Efficiency Solar Cell program uses optics (dichroic films) to concentrate incoming sunlight by 20-200x, and split it into constituent spectra, which fall on many small solar cells of different chemistries, each tuned to maximize the conversion of different wavelengths."
Re:Screw soldiers, NASA will love this. (Score:2, Informative)
The solar (photovoltaic) panels used in space are already very efficient and use some of the most expensive materials such as being made out of Gallium Arsenide (GaAs) with multiple doped layers to collect at different valence levels. Panels used in space also receive sunlight that doesn't pass through the atmosphere allowing for higher power gains.
The problem has always been with getting high efficiency rates on earth without the high cost.
Re:No problem with this (Score:2, Informative)
"As of May 2012, SpaceX has operated on total funding of approximately one billion dollars in its first ten years of operation. Of this, private equity has provided about $200M, with Musk investing approximately $100M and other investors having put in about $100M (Founders Fund, Draper Fisher Jurvetson, ...) [22]. The remainder has come from progress payments on long-term launch contracts and development contracts. NASA has put in about $400-500M of this amount, with most of that as progress payments on launch contracts."
Don't be a PV efficiency snob (Score:5, Informative)
Developments like this are awesome, because they open up the possibility of doing exactly what the summary describes -- using solar power to recharge things where size / weight / surface area is at a premium.
But those sorts of scenarios are few and far between. Most of the time, cost is the limiting factor, and these high-efficiency designs are always costly.
That's okay, though: PV panels are already plenty efficient for their desired function in most cases [ucsd.edu].
Cheers,
b&
No. (Score:4, Informative)
If that were true, this would only work if the sun were at a very specific angle. But that's not how it works. It concentrates light from the entire sky into a narrow beam which is then split into different wavelengths. It says that right in the summary.
Re:No problem with this (Score:4, Informative)
No, he means forward-looking scientists working for government money (so, just like it should have been). So far the general public was the greatest beneficiary of DARPA projects. Computers, Internet, GPS to name the few...
Re:No problem with this (Score:2, Informative)
I am not sure you understand what DARPA is. They don't do the research, they read proposals submitted by companies, universities, non-profits, etc, and allocate US tax dollars to whoever they think is most likely to successfully develop the technologies they need. For example, the solar cells noted in this article are being developed by University of Delaware, using DARPA money.
Not new with DARPA (Score:4, Informative)
I'm surprised that DARPA is getting all the credit here; the approach isn't new with DARPA.
That approach is known as the "spectrum splitting" approach. Some older work was the NASA "rainbow concentrator" array concept:
http://ntrs.nasa.gov/search.jsp?R=20110024141 [nasa.gov]
http://www.techbriefs.com/index.php?option=com_staticxt&staticfile=/Briefs/June03/NPO21051.html [techbriefs.com]
In general, spectral-splitting concepts do need to track the sun, and so they're envisioned more for concentrator systems than for flat-plate arrays.