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40% Efficiency Solar Cells Developed
gtada writes "A story published at Physorg.com discusses recently published research into the fabrication of solar cells that surpass the 40% efficiency milestone. Such devices would be the high water-mark to date, and hint at the possibility of even more effective technology. 'In the design, multijunction cells divide the broad solar spectrum into three smaller sections by using three subcell band gaps. Each of the subcells can capture a different wavelength range of light, enabling each subcell to efficiently convert that light into electricity. With their conversion efficiency measured at 40.7%, the metamorphic multijunction concentrator cells surpass the theoretical limit of 37% of single-junction cells at 1000 suns, due to their multijunction structure.'"
There is really no shortage of sunlight anyways. If only solar cells could be made cheaply. I suppose this will be great for satellites though.
It's another gallium-based technology. That's going to limit it. There's just not that much gallium available. 30%+ efficient cells using gallium have been around for a few years, but other than on spacecraft, and the Stanford Solar Car, they're too expensive to be useful. They talk about "concentrator cells", but that means mirrors and trackers, running up the system cost.
Citation: King, R. R., Law, D. C., Edmondson, K. M., Fetzer, C. M., Kinsey, G. S., Yoon, H., Sherif, R. A., and Karam, N. H. "40% efficient metamorphic GaInP/GaInAs/Ge multijunction solar cells." Applied Physics Letters 90, 183516 (2007).
not even remotely. plants are efficient at converting photons to an immediate energy source but the vast majority is used to keep the existing tissues alive and functioning. esimates I have seen for the efficiency of converting light, CO2 and water into biomass ranges from less than 1% to 5% depending on the species.
Sigs are too short to say anything truly profound so read the above post instead.
Hmm.
- Efficiency: This article talks about brightnesses of 100 suns. Well what about 1 sun? Or fraction of that (cloudyness)? Are these efficiencies realized then too? If not, does the technology still work at or near where that is?
- Power cost: I've seen it said that many solar cells don't give back the energy required to manufacture them. By that I mean, acquiring the materials (mining, etc), refining them, and manufacturing them all take energy. How many days/months/years would it take to "pay back" the cost of manufacture, in energy?
- Temperature performance differences: How does it perform in low (or high) temperatures? A lot of us live in places where it gets cold for long periods of the year. This also has the associated problems with snow build-up, and getting that OFF of the panels.
- Monetary cost: How much will this cost at the consumer level, for which wattages? How big would they have to be to cover some typical consumer usages?
- Power storage: With solar, it all eventually comes back to storing the power, as they obviously don't operate in darkness. So how much would the batteries cost (initially, and in maintenance) to make this a viable power solution? How much wattage would you need to have enough "storage" for nighttime? Or more practically, for a few cloudy/rainy days in a row?
Some of these issues are universal to ANY solar technology, but some of them are specific to this as well. All need real answers.when the article talks about hundreds or thousands of suns, it means they used mirrors and lenses to concentrate the light that falls on a much larger area to then fall on the solar cells. this leads to the solar cells generating a lot more electrical power and thus makes it more economical to produce power from soalr energy as compared to not using mirrors or lenses to focus light onto the panals.
Sigs are too short to say anything truly profound so read the above post instead.
Solar is by far my favorite power source. But like every other power source, it is really just a byproduct of the actual energetic reaction. I think I can accurately say that solar power is second-hand nuclear power. Following this reasoning the other power sources may be seen as third-hand nuclear power.
As another posted stated, even if you make the solar 100% efficient (wouldn't that be something!) you still have to store or transport it - since on average the sun is hitting half the Earth's surface at any given time (with much of that surface being water).
I have high hopes for solar - but it always strikes me as strange that we already have this amazing technology of nuclear power - it's here now! We HAVE it!
Plus, nuclear power can make a nuclear rocket! I don't know of any solar rockets yet.
Read my Very Short "Stories"
The cost of the cells is only one part of the expense of the system. With sufficiently inefficient cells, they could never be installed economically. IIRC, it is possible to make amorphous cells for just about free but there's just no point because they are so darn inefficient.
http://en.wikipedia.org/wiki/Solar_cell
So yes, this depends highly on the materials used and manufacturing process as to whether the energy payback is an issue or not. 1-20 years? Let's hope this technology is on the low end of that scale.
Also, two more issues came up that I forgot in my original post:
- Exotic Materials: The materials advertised in this article are not... common. I highly doubt this helps either the mass production price, or the long-term availability of such.
- Lifetime: How long does a panel actually last? Few manufactured items of any kind have infinite lifespans. Is the manufactured solar cell "stable" chemically/physically? This ties in slightly to my old heat/cold question, but when stressed by weather, will it hold up?
Most of my questions are challenges to be overcome, not "Death knells" to trying. But they're also things to be aware of when anything's announced with too much enthusiasm.http://hardware.slashdot.org/article.pl?sid=06/12/ 06/027228
:)
Ahh well. More publicity for Spectrolabs...
The solar cells are extremely expensive due to the Gallium in them. It's cheaper to have 1 solar cell with a thousand mirrors reflecting onto it. Hence the stellar luminosity of 1000.
Silence is golden... and duct tape is silver.
Yes, and we have the nuclear waste for oh, I don't know, a few HUNDRED THOUSAND years ...
Only with stupid old technology. The Integral Fast Reactor generates 100 times less waste and it's only hotter than ore for a few hundred years. We should be building one at Yucca Mountain as a national security priority.
Fusion will be great in 40+ years, but that's a little late to act. We could have one of these running in probably 5 years.
Solar, at 40% efficiency would still require covering something like 8% of the land surface area of Earth to meet current-day demands. Wind is too variable, hydro is too small - we basically have coal and nuclear as the two viable baseload options.
Obviously, TBPB don't want to end anthropogenic global warming. It's left as an exercise to the reader to speculate on why.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
All the more reason we need to establish reliable mining on the moon. Concentrations on the moon are about 80% higher than on Earth. You know, there is a lot of history ahead of us and maybe Lunar mining would allow future infrastructure that at this point in time boggles the imagination.
Shh.
What isn't being trapped by jumping electrons (that other 60%) is going to go into heat - what we need is a heat engine on the back side of the cell recovering that other 60% ...
Solar is great and all but what about the moon? Sometimes it's bright as hell out there but does lunar power get any press? Nooooooooo.
Need Mercedes parts ?
This is good news. I can not wait to have affordable solar cells to power a laptop. On board colar panels until now only can extend battery life for a laptop. There are foldable panels which generate enough power (26 watts) for a power friendly laptop: http://www.ascscientific.com/solar.html For a laptop with solid state harddrive and power friendly CPU, onboard solar cells might soon be enough.
According to my spam folder, solar technology from China is the next best thing to sliced bread. Buy early. Buy often. :P
Unfortunately a heat engine that would use even a significant amount of that 60% heat is going to require temperatures greater than the operating temperature of the solar cell. The solar cell itself is in fact a heat engine operating at roughly 42% of the theoretical maximum efficiency, which compares well with all but the biggest fluid based engines.
However, if you want heat, rather than work, you should be able to collect all of that 60% - thermal desal, domestic hot water, space heating - all are easily doable.
Thank you... One of the things that originally drew me to reading Slashdot was that when someone would make an outlandish comment, someone else would 'run the numbers'. It's good to see that some traditions are not completely dead.