Concentrated power: Amonix's solar power generator converts 25 percent of sunlight into AC power.
Amonix
Large investment could jump-start concentrated photovoltaic deployments.
A California-based startup, Amonix, has received $129 million in venture-capital investments to further its commercialization of concentrated photovoltaic technology. The company's product combines powerful lenses, a tracking system, and solar cells for large, highly efficient solar-power installations. The funding could give the company, and the emerging field of concentrated photovoltaics, the boost it needs for widespread utility-scale deployments.
"We've looked at 100 solar companies in the last 18 months, and Amonix is the one that stood out to us as having breakout potential," says Ben Kortlang, a partner at venture capital firm Kleiner Perkins Caufield & Byers, which led the recent investment.
Amonix recently launched its newest solar concentrator, which converts one fourth of the sunlight that falls on it into AC electricity. That's compared with the approximately 18 percent system efficiency--including inverters that convert solar's DC power to useable AC power--of the most efficient photovoltaic systems that don't use special optics or track the sun.
To collect sunlight as efficiently as possible, Amonix starts with a massive 23.5-meter-by-15-meter array. The array is covered with thin, plastic Fresnel lenses, each measuring 350 square centimeters, that focus sunlight to an area that's .7 square centimeters. The sunlight, concentrated to 500 times its normal intensity, hits an ultra-efficient multi-junction solar cell that converts 39 percent of the light into electricity. The cell, made bySpectrolab, is the most efficient in the world, demonstrating more than 41 percent efficiency in lab tests. To further enhance performance, Amonix uses a tracking system that keeps the lenses pointed within .8 degrees of the angle of the sun throughout the day.
Utility companies, however, have been reluctant to invest in any concentrated photovoltaic systems due in part to the device's high level of complexity. Proper functioning of each component is crucial because the lenses require very precise alignment with the sun in order to focus light on the solar cells. "The difference between being in alignment and being one degree off is the entire system works or it doesn't," says Johanna Schmidtke, an analyst with Lux Research.
Amonix's technology already accounts for some 13 megawatts of installed capacity, which represents more than half of all installed concentrated photovoltaic capacity in the world. And so long as Amonix can prove its reliability, its technology offers several distinct environmental advantages over other types of utility-scale solar.
Concentrated solar power--solar thermal systems that use highly concentrated sunlight to create steam that drives electric turbines--has begun to run afoul of environmental regulations because they typically require vast amounts of water. In contrast, concentrated photovoltaics don't require water to generate electricity and, because of their high efficiency, they don't blanket large swaths of land.
The recent venture capital funding will allow Amonix to scale up manufacturing, and perhaps more importantly, will strengthen the company's balance sheet. "If you are going to be a supplier to the utility industry, you have to be a well-capitalized company that can stand behind its deployments," Kortlang says.
Semprius makes solar modules using tiny cells that need less cooling.
A 30-megawatt plant will be one of the largest to use the technology.
A startup says it can beat the performance of the most efficient solar cells on the market today.
A Solar start-up company that started up back when drugstores had soda fountains
It's interesting to note that Spectrolab's multi-junction technology was originally developed to meet the needs of satellite makers, to power their increasingly larger and more complex satellites. The company was founded in 1956 by entrepreneur Alfred Mann, to develop optical components for the government and military. It soon got into solar photovoltaic cells; and it's quest for ever-increasing conversion efficiencies, to meet the needs of satellite makers, goes back several decades. The company is presently, according to its literature, "the primary multi-junction solar cell and panel supplier to nearly all the world’s prime satellite contractors". It's not a pure-play investment, however, since it was purchased by Boeing in 2005.
Add high efficiency thermoelectrics
I understand that quantum well thermoelectric generators can have over 15% efficiency for temperatures above 200C. It could help eek out another 5-10% total efficiency out of their system, should it be feasible.
Re: Add high efficiency thermoelectrics
The only problem with this is that in order to get high efficiency from the thermoelectrics, the temperature has to be high, which means the operating temperature of the solar cell has to be high. This degrades the performance of the solar cell, and then there is the ever present cost/benefit interplay of adding them on. The added cost will probably not add enough efficiency to make it worthwhile. Just speculation though, I'd imagine people have thought of this route before, and that is why it isn't practiced.
If the PV cells themselves are 39% efficient, why is the system efficiency all the way down to 25%? That's a 36% loss -- surely the inverters don't account for all of that. What else is sapping energy here?
Re: Why the drop in efficiency?
One would suspect it's a cost/benefit problem. Ultra high efficiency solar cells are very expensive, plastic lens are cheap.
Ultimately the question is not efficiency, it's cost per kilowatt and durability.
But then i'm just a chemist, not an engineer.
Re: Why the drop in efficiency?
Fresnel lenses are not optically so great, but they are flat and cheap, the 40% efficiency is from the light the lens focuses on the pv, not all the light hitting the lens.
SolFocus.com has a similar product, but they use dual mirrors and prism optics rather than fresnel lenses.
SkylineSolar has a cheaper concentrator that is only 10 or 20x, but has a good ROI.
water not an issue, aging of plastic?
The solar thermal I've seen, like Ausra and eSolar, only uses water for washing the mirrors. The cooling of the steam is done in closed towers. They too get about 25% efficiency from sunlight in to electricity out, but use simple glass and steel instead of plastic Fresnel lenses. As others have mentioned, they can also store the steam for later use, something that Amonix and Stirling can't do.
I wonder how the plastic lenses would age in harsh desert sunlight. These facilities are supposed to last for decades, after all. The plastic would also get abraded by dust more than glass mirrors.
Some solar companies have roadmaps to get to grid parity and beyond, while others simply look at today's financial picture and carve out a niche assuming a static cost structure. The cost of solar power is on a relentless decline as new competitors emerge, so anyone with a reasonable roadmap to compete needs to have a plan to make a profit in this declining cost environment.
IMHO, this approach seems awfully complicated in a world where I predict that simplicity will rule. Anyone who has ever lived in a sunny climate knows that all plastics fall apart over the years due to UV. Glass survives, however. And then there's the automatic tracking mechanism and controls that passive panels don't need.
In this technology's favor, however, is the fact that it doesn't need water. Not needing water will turn out to be a price of entry for any concentrating solar. Think about it: any concentrating solar MUST be sited in a location where water is scarce - clouds of any kind kill performance. Hence, any concentrating solar that needs water is really a non-starter!
May they find a way to get the reliability up and cost down - Good luck to them!
Plastic lenses can be sandwiched between thin glass veneer, which is done for automotive safety glass. an interesting idea is holographic lenses which can concentrate light no matter the incident angle of the sun, which would save money on suntracking rotors or parabolic mirrors.
Very few companies are working on parabolic dishes which heat up to 1,200 deg C. They also do not need water except to clean mirrors. This high temperature can be stored in a smaller space because its so high and generate electricity in the 30% - 35% range. one has already been built in Tianjin by a US company, Solar & Environmental Technology Corp. They came out of an original US company in the space that featured in NREL's inauguration, Omnium G. They use air as a transport medium and ceramics as a 6 day storage medium. No other solar or wind has as much storage built in. Now its like hydroelectric for solar, except that...you don't need to have a river or valley to flood!
Why do you have to use water to clean mirrors in the desert? Why not use compressed air? Yes, it takes power, but that's more plentiful on a desert solar installation than water.
Re: Cleaning Mirrors with compressed air
sometimes you can, but compressed air pushed particles around the surface before they detach.
blowing silica (sand particles) around a mirror is likely to scratch it. Is the same hardness as glass (made of silica) so will scratch.
using water reduces scratching a whole lot.
Re: Cleaning Mirrors with compressed air
you don't need to push, you pull. it's called a vacuum.
Baffling to read that csp (solar thermal) requires "vast amounts of water" (with a link to another story making same claim, neither story containing any explanation whatever).
It is nuclear power that requires vast amounts of water.
CSP (solar thermal)uses some water to wash mirrors, but this need not be much at all. Modern car washes recycle filtered water, very little is lost. This is simple technology, surely not beyond the power of the minds at MIT to comprehend.
Perhaps some writers are overly influenced by the red herrings drawn across their path by the PR department of PV industry???
CSP (solar thermal)is simpler, cheaper, more reliable than PV, and produces more power for longer hours with cheaper storage (in any commercial scale application, home rooftop scale not included).
The SEGS power plants at Kramer Junction CA consists of 9 plants built 20-26 years ago, they have NEVER broken down, they have NEVER failed to meet their designed capacity.
Check it out here:
http://en.wikipedia.org/wiki/Solar_Energy_Generating_Systems
Newer CSP (solar thermal) plants are even better.
Hey,
The thing that isn't being explained is 'steam engineering'. All our systems to date, heat water, wtr expands across turbine blades, condenses back to wtr, heat wtr, etc.
The nature of wtr/steam is 1 BTU of energy heats 1 pound of wtr 1 degree. It heats 1 pound of steam, 1/2 degree. Any temp over 212 exiting the turbine is wasted energy in the condenser but if water is free, -ship at sea- who cares?
Exactly right. I have been involved with the development of pv technology-orginally for ues on early satellites, since the the 60's. Improvements in conversion efficiency have been very slow, and it is obvious we are on the asymptote.
CSP is by any measure the preferred approach, and as you state,water use is a canard; recycling at levels of efficiency approaching 100% are entirely feasible.
It is critcal importance that we take the correct path before---not during or after--major investments in solar energy.
By the way, if we are looking to create jobs, let's remember that no matter what technological twists eventually are chosen for PV, they will wind up being fabricated in China, just like all simple semiconductors are today
this is not inherently a problem. the problem is letting $'s go overseas to buy energy.
The progress in solar power is amazing. In 1950 or so we worked only on thermal systems with concentrated sunlight on optical interference in thin layer "Black Chromium" covered stainless steel tubes. This was later commercialized by the LUZ company. There seems to be a problem with large surface solar cell arrays, namely wind resistance of such flat structures. This means an additional strengthening and/or turning the array of the collector facing the wind on the narrow side.
I have the experience of our neighbor's flat solar collector crashing down in a stormy night.
Anyway I am sure that the solar energy techniques will improve steadily to help to overcome the energy crisis.
The subject of an excellent provider of energy and we hope it spreads to the whole world with Fe to provide alternative routes for the SA Air and was the cause of global warming ... And Charcot me Moukq Apple Jewels http://apple-gems1.blogspot.com/
Thanks
The issue to transport solar energy to countries with a less sunny climate is still not solved. A funny idea how to collect and market 100% concentated solar (canned sunshine) can be found under
http://quatschtronauts.wordpress.com/2009/11/28/canned-sunshine/
Anyone any idea to get this vision realised?
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erbium
338 Comments
other concentrated solar
modular concentrated solar, such as those made by stirling energy in AZ DON'T need water for steam production, only the minimal amount needed to occasionally wash off the mirrors.
http://www.stirlingenergy.com/technology.htm
And, being modular, a field of these starts producing electricity as soon as you hook up one of the modular elements, instead of waiting till expensive construction is completed on towers, and a whole field of mirrors.
It's pretty stupid to use vast quantities of water in desert areas, environmental regulations or not. you then have to get the water, pump it, take it away from other uses and NOT use areas with vast potential for sunlight if no water is available. Even these plants could be designed to recycle the water with the proper condensers but that is a bit more expensive. I mean your car doesn't use 100 gallons every few miles like steam locomotives used to. you have a radiator and the fluid is recycled.
The upside to using solar towers is, unlike modular, you can incorporate an insulated heat storage tank holding whatever the heat transfer medium is, e.g. molten salts, to keep producing electricity to end of peak hour, increasing payoff by matching use curve better.
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Devere
32 Comments
Re: other concentrated solar
Did you even read the article?
The article is about concentrated PV, not concentrated solar for heating water into steam.
Reply
erbium
338 Comments
Umm, yeah..
my point was that modular solar thermal doesn't have the drawbacks of intensive water use for steam pointed out for large scale solar thermal.
'because they use vast amounts of water' in the page above.
Did YOU bother to read the article?
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