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Optical Concentrator To Make Solar Power Cheaper
Al writes "Researchers at a company called Morgan Solar have developed a simple solar concentrator that promises to cut the cost of solar energy. The Light-Guide Solar Optic (LSO) consists of a specially-molded acrylic optic that traps light and guides it toward its center using total internal reflection. At the middle of the concentrator another optic made of glass receives the incoming light, amplifies it and directs it toward a small solar cell at the very center of the device. Unlike other concentrators, the light doesn't leave the optic before striking a solar cell so there's no air gap, and there's no chance of fragile components being knocked out of alignment. This could significantly reduce the cost of manufacturing this type of solar cell."
That's actually pretty cool. By concentrating the light, they need less photovoltaic material per square foot of land used for solar. I'm curious how the efficiency of photovoltaic cells varies with the concentration of light. Will 1 square foot of sunlight concentrated into a few square inches of photovoltaic cells produce as much power as 1 square foot of unconcentrated photovoltaic cells?
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The original concept here is flat fiberoptics-like lens, so you can transport more concentrators in the same space and there will be no misalignment during assembly, because small pv cell is glued onto back of these lens, not held at a distance.
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Neat idea, but how do they get rid of the heat of 1000 suns? Does the IR escape because it isn't reflected the same way?
From the picture, it looks a lot like a fresnel lens.
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... about concentrating solar power.
now we need to go OSS in diesel cars
My house has an nearly unbeatable infestation of small ants, and I can't help but think just what a magnificent burning lens one of these would make minus the solar chip.
But aside from that, there are some other pretty nifty uses for concentrated sunlight. I am definitely curious whether the lens can be scaled up to a square meter or more, enough to possibly melt glass or aluminum.
I live in LA. To the east of us is the Mojave Desert, and there's already quite a bit of solar power out there right now. The big issue is transmission lines to get the energy from the Mojave to LA. Building transmission lines requires political action, and that's slow and uncertain because of NIMBY. I have photovoltaics on my roof, but objectively, if you look at the price of land where I live versus the price of land in the Mojave Desert, it's pretty clear where you should be building these things.
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This should arrive just in time to recharge my flying car. I can hardly wait!
It's TFA's fault, but even so.
There is no "amplification" taking place at all, merely concentration. Those are two VERY different things.
Neat idea, but how do they get rid of the heat of 1000 suns? Does the IR escape because it isn't reflected the same way?
About 80% of the energy is absorbed across the entire solar spectrum. Yes, it will radiate some heat away as IR, but mostly the heat is convected away by the surrounded air. You're right, though--this is a design concern for these devices, as temperature effects efficiency and lifetime.
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They keep them in the dark so they don't get hot.
or from wikipedia:
The solar cells require high-capacity heat sinks to prevent thermal destruction and to manage temperature related performance losses...In May 2008, IBM demonstrated a prototype CPV using computer chip cooling techniques to achieve an energy density of 2300 suns.
of this particular solar advance means not only greater efficiency and lower cost, but also MUCH MUCH greater feasability for wider adoption by areas of higher latitudes. In addition, this particular advance would appear to reduce the detriment of partial occlusion by some factor.
This concentrator technology also reduces the manufacturing use of rare metals for these systems and that is another huge benefit also.
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Amplifying light with a glass 'optic' would be quite original. Concentrating it yes, but amplifying it?
I would be very impressed if they have actually achieved it.
There has been so many news about breakthrough in power cells technology... making them cheaper and more efficient... but why the hell are they still so damned expensive?
No net decrease in surface area. No proven increase in efficiency.
There's a third axis; cost per watt. Acrylic is cheaper than PV silicon.
(Actually the relationship of surface area and efficiency is fixed, so it's really a second axis.)
-Peter
Huh? My post, which you were replying to, didn't say anything about storage.
LA's problem with lack of capacity shows up on hot days in the summer, when everyone is running their air conditioner. That's exactly when the Mojave plants will be running at their maximum production. Because of this excellent match between peak production and peak demand, there isn't really an issue with storage. It's a perfect fit.
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does that mean someone behind it will only see black?
... do not look into solar concentrator with remaining eye.
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Not really a lens of any type. Its an example of non imaging optics. A lens, Fresnel or otherwise, or a mirror, produces an image of an object at its focus. So, as the sun moves across the sky, its image would move across the plane of focus. So you'd either have to make that image plane big enough to contain the imaged sun track over a day or move the apparatus. Non imaging optics reflect or refract incoming light rays from any direction on to a single point as well as focus the light from a large aperture onto a smaller area.
While the idea of non imaging optics in general isn't novel, the design of this device might be.
Have gnu, will travel.
Or use the waste heat to drive a stirling engine as a booster perhaps. I know just regular solar panels get wicked hot on the backs of them when sitting in full direct sun, I mean it is black stuff sitting behind a clear surface and stuck on a metal backing, it gets *hot*. Just doubling that heat would turn it into some sort of decent viable optional energy source.
And why PV? Instant electricity from it, solid state, no moving parts, pretty spiffy stuff. Big solar concentrators with turbines are cool too, we have those for giant megawatt scale production now, but we don't have them for joe homeowner yet or joe back packer, PV fits the bill for those purposes.
Which is why in actual practice the land under the solar collectors is made as sterile as they can afford to make it. We need to accept that getting most of our energy from desert solar will probably require destroying the ecology of several percent of the deserts of the southwest. I think that's an acceptable trade off, but for those who insist on a "greener" solution I suggest they push for nuclear power.
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or a stirling engine.
These comments are my personal opinions and do not necessarily reflect the opinions of the other voices in my head.
A flat panel can be pointed at the position of the midday sun, and left stationary would have a reduced aperture to the sun as a result of the angle in the morning and evening. Turning the whole assembly helps. But, if there are many panels, they would have to be spread out or else some will shadow parts of others. Basically, it comes down to capture area. If you have a 10 meter by 10 meter area, there's only so much sun that enters it. In the morning and evening, there is less sun entering that area because of the angle. If you have one giant 10m by 10m panel that in there that gets tilted, its shadow will be outside the area, and you're actually capturing sun that would go outside. If you are have lots of small 100cm x 100cm panels, tilting them doesn't help because of the shadows. Remember, there's less total sunlight to get at an angle. Tilting is only an advantage when you have less than 100% coverage, and are willing to lose sun at midday.
Tilting is also a mechanical thing which means some kind of control mechanism, more exposure to failure, and greater maintenance costs.
An optical structure that would funnel light from any angle over a reasonably wide angle range would be the ideal solution. It would handle the change from morning to midday to evening, and would handle the diffuse light of cloudy weather. That's the thing to work on.
now we need to go OSS in diesel cars
Heat water with the waste heat.
When the water tank gets too hot you heat the house with it (or dump the heat outside).
I'd use an oil loop between the collectors and an over-sized water tank.
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The plastic is the problem. Can't we do it with all glass? If you use a solar furnace you can make it with solar energy. Alternately, if you get enough PV, you can run an electric furnace. Either way, plastic is nasty and sand is everywhere. (Some of the additives in glass are nasty, to be fair. But not all glass is nasty. All plastic is either nasty or has a short life when exposed to UV. Much is nasty AND has a short life.
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Acrylic rapidly becomes yellowed when exposed to ultraviolet, and especially under very high-intensity light, even if it has anti-yellowing chemicals added. This article, Applications and Limits of Polycarbonate and Acrylic Lenses, explains "... yellowing is a sign of degradation of the plastic molecule. Heat and ultraviolet act to break the molecules. This surrenders the intrinsic strength of the material as the molecular structure no longer consists of long intertwined chains but fractured segments. This may be reflected in reduced strength of parts with formed surfaces as these surfaces tend to localize stresses."
The article, A Cheaper Solar Concentrator, referenced in the Slashdot story says, "With a flat bottom and convex, mirrored top, the [Morgan Solar] optic receives the incoming barrage of light at a concentration of about 50 suns and amplifies it to nearly 1,000 suns before bending the light through a 90-degree angle."
The article does not explain how there is a concentration of 50 times before the light reaches the optics. The article is wrong in using the word "amplifies". The correct word would be "concentrates".
To have a 1,000 times concentration, the area of the optics must be 1,000 times larger than the area of the solar cell. That delivers 1,000 times the heat, also.
Morgan Solar's investors page says, "Morgan Solar was incorporated in June 2007 and is currently well funded by a start-up investment from our angel investor and Chairman, Eric Morgan." Apparently the company was funded by the inventor or someone in his family. It says, "Our plans call for securing our next round of investment funding by Q1 2009. If you are a venture capital company or a potential partner-investor interested in exploring investment opportunities with our company, please contact us."
Was a Slashdot editor paid to allow this story? Did Slashdot profit? Was Technology Review paid to run the story? I think that articles about companies that are soliciting investments should have a statement about whether or not someone was paid.