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But traditional concentrators are complicated. Since the lenses or mirrors that focus light need to face the sun directly, they have to mechanically track the sun. They also heat up the solar cells, and so require a cooling system. As a result, although they redirect light with more intensity than the hologram device, "they're unwieldy...and not as practical for residential uses," says National Renewable Energy Laboratory spokesperson George Douglas.
Holograms have advantages that make up for their relatively weak concentration power. They can select certain frequencies and focus them on solar cells that work best at those frequencies, converting the maximum possible light into electricity. They also can be made to direct heat-generating frequencies away from the cells, so the system does not need to be cooled. "In this way, you are efficiently using only that part of the sunlight that really matters," says Selim Shahriar, director of the atomic and photonic technology laboratory at Northwestern University in Evanston, IL.
Also, different holograms in a concentrator module can be designed to focus light from different angles -- so they don't need moving parts to track the sun.
Prism Solar's system incorporates these advantages. Nevertheless, to be competitive with other solar technologies available today, the company might need to reduce its price below $2.40 a watt, says Christo Stojanoff, professor emeritus of engineering at the Aachen University of Technology in Germany.
CEO Lewandowski says the holographic modules will cost about $1.50 per watt in a few years, using their second-generation technology, which will have solar cells sandwiched between two glass panels containing holograms. At that price, they'll start to compete with fossil fuel-generated electricity, which now costs almost three times less than conventional solar electricity, according to San Francisco, CA-based research and consulting company Solarbuzz.
The modules' intensive use of glass could be adding to their cost, says Douglas. Still, such a novel idea for a concentrator, using holograms, could be a lucrative investment because it needs less silicon than flat-panel modules and therefore saves money. The high demand for solar cells in Germany and other European countries "has now outstripped the supply, which has [led to] a silicon shortage and a shortage of manufacturing in the photovoltaic world," he says.
Although the idea of holographic solar concentrators has been around since the early 1980s, no one has developed them commercially yet, according to Professor Stojanoff, who has investigated the technique extensively. His company, Holotec GmbH in Aachen, Germany, researches and manufactures holographic materials. Also, Northeast Photosciences, a Hollis, NH-based company, came close to manufacture, before it went defunct for reasons unrelated to the technology or to finance, he says.
So, if all goes according to plan, Prism Solar could be the first company to manufacture and sell holographic solar concentrator modules.
Guest (dan)
my question is being that silicon is found
in sand why is it so hard to comeby. Second of all , if other expensive materials are needed can it be massed produced enough to provide every house in the world with solar energy. A world where every rooftop has both wind and solar generation.
Guest (Barry)
The Silicon used in the manufacture of electronic compnents is man made, not raw and or refined (Chemistry.org). Other generating sources are not as efficient as solar, but if used all together it will free up any need for remote source provisions. Wind generator's, heat collectors for water, and solar panels are all just some of what an individual home can do, but what about grand scale generation for those who require tera watts, or giga watts? The answer is beneath their feet about a few thousand feet down. The largest natural battery in the world is the planet itself. and we have NOT even begun to tap into it's natural resource for electricity. The Natural Thermal Conduction Reclamation Process is the most efficient, but it is one they do not discuss in any circle. Why? Who knows?
Guest (Inquiring jv)
Keep asking. Don't stop....you may be 'on' to something!!
Guest (Jonni Blaze)
Silicon 4 Science - To answer your question
Think about it...
Do you really think the Power companies - or for that matter - the Govt - would like for us to be free of the grid ??
The power companies want our money
The Govt wants to control us.
Working Together they both get what they want...
That is why there is no REAL tech breakthroughs in eletrical energy generation. That tech gets squashed.
Guest (joey)
your incorrect paranoia is utterly astounding. new breakthroughs in science are made all the time, and many get to market. if you feel a little oppressed, i wouldn't say it's because of anyone squashing ideas.
Guest (dinther)
You mean Geothermal power right? Very common here in New Zealand. See http://www.nzgeothermal.org.nz/geothermal_energy/education/wairakei.asp
Are you telling me they don't use this in geothermal area's in the US?
Guest (John Nicholson)
For us here in the US geothermal power has been costly. And, not much on the number of hot spots. The best way to use geothermal power here is as a heat sink as with a heat exchanger.
Guest (Lan Mandragoran)
What's really going to happen is not what you're imagining. You're thinking that everyone is going to run out and buy PV cells and put them on their roofs and then no one will need the power company anymore. Turns out what will happen is that some people will, and some people won't. And for now, even the people who will buy them are going to still need power on rainy days, and they'll still draw from the grid. Eventually though, what'll happen is that the power companies will no longer have to produce power, it will be generated by the people, but the power company will still have to be there to support the power grid so that all those people who don't run out and buy their own PV cells can get powered by the rest of us who do go out and buy them. So the money from those people will go to the power company, who'll take a little for maintaining the grid, and the rest will go to you who've made it. Your paranoia is entirely misplaced.
Guest (Maury)
> Do you really think the Power companies -
> or for that matter - the Govt - would like for
> us to be free of the grid ??
Of course! Geez, you think they LIKE paying millions on millions of dollars to deliver a product to your house, and not make a penny doing it?! Reducing delivery costs improves their bottom line, trust me, if they could get people off the grid, they'd do it. It's not like you'd stop buying the product, after all, you drive TO the gas station to get their product.
> The Govt wants to control us.
I hope your tin foil helmet is in good working condition. Meanwhile for those of us who live on planet Earth, buying a few compact florescent lights is something that actually helps.
Maury
Guest (mas)
Solar only true renewable source of energy
Geothermal energy, though quite plentiful, is not renewable. When the inner heat from the Earth is exhuasted, the carbon cycle will be interrupted and life on Earth will gradually die out since carbon will no longer be recycled and expelled by volcanos. Fortunately, you would have to reduce the energy in the mantle by a tremendous ammout before effects are seen.
Guest (Eric)
Yes but the sun is going to burn out someday
so we'd be better off harnessing the gravitational energy of the black hole at the center of the galaxy.
Guest (John Nicholson)
No true renewable source of energy
The sun will also expand and eat the earth. Earth will gradually die out since the global warming will be more than carbon fuels. Fortunately that will be in about 5B years. So no by your statement there are none that are renewable. So, you need to learn that words do have meaning in the present tense. Renewable means natural energy that does not cause waste.
Guest (JJK)
my question is being that carbon is found
in even more places than silicon, why are diamonds so hard to come by?
It must be a conspiracy by The Man to keep us down somehow.
Guest (ss)
Re: my question is being that carbon is found
Diamonds aren't that rare. They are just marketed very well. Google DeBeers conspiracy.
Guest (mike)
It's about as useless as sand as an ore and consumes a lot of energy to refine.
Guest (ted)
Aluminum manufacturers are usually ble to buy electricity very cheaply.
Guest (peter segaar)
in my country (Netherlands) the big alu melter Pechiney sits on the neck of our only nuclear reactor (that the guv boys decided NOT to shut down, the b....s). Their contract with the nuke boys is top secret. What do you think they will pay for a kilowatthour?
Guest (Paul Palmer)
It's funny that you chose diamonds because the DeBeers Company of South Africa runs a well known conspiracy to keep diamonds off the market and the price high. They've been doing it for about a hundred years, and their tentacles reach to Russia, Amsterdam and the US. Diamonds could be much more plentiful without their market control. So far as I know this only holds for diamonds.
Guest (Silicon chemist)
It takes an enormous amount of energy to convince otherwise. The various reduction processes used require enormous temperatures, and the high purity required for a solar cell requires multiple processing steps.
One could argue that hydrogen should be easy to come by, as we have an ocean full of it. Unfortunately, like silicon, it has already combined with oxygen.
This brings to mind the whole "Dust to Dust" calculations of solar. Whether it truly is renewable. The sun is only as renewable and efficient as the process involved in producing, using, maintaining, and destruction or recycling of the panels themselves.
If the panels are not recyclable, then its not renewable. Eventually you will run out of a particular resource needed to produce them. Thus making the sun's renewable energy is mute. For the whole process is as strong as the weakest link.
Guest (Paul Allen)
Solar Cells are made starting from silicon of extremely high purity. Trace impurities interfere with the photoelectric effect. Removing these impurities takes quite a bit of electricity. Indeed, a solar cell has to operate 15-20 years before it generates as much electrial energy as was used to manufacture it! This is the principle reason solar cells are not cost effective.
Guest (Carl Lenox)
This is absolutely untrue. Many life-cycle studies have been done on this issue. PV modules take 2 to 5 years to generate the amount of energy required to manufacture them. The biggest contributor to the energy intensity is the aluminum frames.
Silicon for solar cells (and semiconductors) is currently very expensive for two reasons. First as noted, it needs to be very high purity. Second is simply supply and demand. Silicon demand has skyrocketed as PV has taken off. Sometime this year, the PV industry will be using more silicon than the rest of the semiconductor industry behind. This took polysilicon manufacturers by surprise. Polysilcion plants are capital intensive and take a couple of years to come on line. So, right now there is a shortage. Most likely, as plants come online over the next coupel of years, there will be overcapacity for a while and prices for polysilicon will fall dramatically.
Guest (CL)
"Sometime this year, the PV industry will be using more silicon than the rest of the semiconductor industry COMBINED."
Guest (Robert Loest)
The payback can be much shorter if you equate dollars with energy. Newer PV panels are made out of silicon wafers unsuitable for semiconductor needs. Newer processes can also manufacture it cheaper. But in the US. tax incentives have simply pushed up the cost by the amount of the highest incentives. The exact same panel in Europe will cost half as much as in the US.
Guest
It is too...I just called. Hey, the issue is energy self reliance. Would you rather we remain dependent on OPEC?
The true key is not the Dollar itself but how much of a particular energy intensive process you use.
If you could some how minimize or eliminate the aluminum for example then the payback for energy will be shorter in that its less energy intensive to produce. The key is finding less energy intensive and renewable process to make it sustainable in the end. Through minimizing resource + recycling
Re: my question is being that silicon is found
sILICOM IS VERY COMMON IN THE sAHARA AND gOBI DESERTS. In fact my friend Muamar has lots of problems clearing the city after sandstorms. Besides if they could be manufactured w/o leaving a carbom footprint, then, why not?
Guest (Harvey)
There is not a word in the article about how the device is actually constructed. This is supposed to be MIT "Technology" review, but it appears to be written for investors and consumers. How does a hologram concentrate light from different directions and of different frequencies onto strips which appear from the picture to be lying next to them? Not a hint of a technological explanation! Like most of the articles in this magazine.
Guest (kitk)
There are always problems with dispersed energy generation. Silicone is indeed incredibly common--and unusable in its natural form. It requires large factories and a hell of a lot of energy to be turned from sand to pure silicone. Solar panels are relatively fragile, and would not easily withstand severe storms. Geothermal sounds great, but unless you have a large circulating body of fluid, like hot water, you will only get a little energy before you have chilled the rock around your well. This is why we have power plants burning coal: they work well at our technology level.
Guest (dash)
subtle difference, but just to keep the technical terms straight. silicon for photocells is very pure (99.9999% pure) and is typically grown in very high temperature crucibles, very similar to the same process for intergrated circuits. see US Dept of Energy links below:
http://www1.eere.energy.gov/solar/silicon.html
http://www.eere.energy.gov/RE/solar_photovoltaics.html
Guest (WangVS)
No, it's not a subtle difference. Silicone is the lubricant you spray on things or the rubberlike stuff you use for caulking, etc. Silicon is an element and is what beach sand and computer chips are made of.
Guest (Peter)
Where do you get the idea that solar panels are fragile? Some experiemental systems have been around for more than 30 years now. They have withstoud quit a lot of storms.
The energy required to produce a modern solar energy system is earned back in less than three years (at mid Northern latitudes). The technology develops continuously and the energy pay back time keeps being reduced.
Guest (Jonni Blaze)
No doubt --
Altho I dont mind that it is written for a layperson to understand...
I would appreciate it, if they would explain some of the "magic" that makes this work tech... ;)
Being a new tech, maybe there is concern of theft of processes or fear that a competitor could gleam just enough info to produce it cheaper. Why make it easy for the competitor to rip you off by giving them the raw information you want. in order to understand the "magic"
Guest (Merlin Brasil)
Here are the pretty pictures and description. Just took a minute of Googling...
Guest (Jerry)
"A layer of holograms -- laser-created patterns that diffract light -- directs light into a layer of glass where it continues to reflect off the inside surface of the glass until it finds its way to one of the strips of PV silicon."
I'm no expert or professional in this field (i.e. I'm a layperson), but that explination is enough for me to understand the concept and be able to recreate their work.
The holigram isn't directly focusing the light like a lens would, rather, concentration occures by accumulation within the pane of glass. The light diffracted by the holigram will enter the glass at a sharp angle, enough so that it will stay inside the pane like light in a fiber optic cable.
Note that not all the light is diffracted by the holigram, and even then only some will actually stay inside the glass.
Reduced cost per watt is great, but I wonder what kind of area efficiency they get with this.
Guest (ismirth)
You can look up how holograms work and are made on google or wikipedia:
rainbow transmission holograms are formed as surface relief patterns in a plastic film, and they incorporate a reflective aluminum coating which provides the light from "behind" to reconstruct their imagery. Another kind of common hologram (a Denisyuk hologram) is the true "white-light reflection hologram" which is made in such a way that the image is reconstructed naturally using light on the same side of the hologram as the viewer.
But because you can layer holograms, and each one can be at a slightly different angle (incorrect wavelength, or angle just goes straight through), then you can have 100 different angles on top of each other, all pointing to the receptor at the side. Kind of like a mirror in a telescope.
Hope this help:) -isabelle
Guest (Xeno)
Effectively, this coupled with waste heat converters and lenses could boost output maybe an additional 2%.
Guest (ismirth)
There really isn't any waste heat to convert, and the whole point is to NOT use a lense. Lense and holograms are two totally different ways to direct the light. You couldn't even combine them.
Guest (waga)
It says it deflects infrared away to keep the solar cells cool -- when I read that I was a little curious if you couldn't actually focus the infrared part of the spectrum at black water pipes, and use that for heating water (or at least pre-heating it, so your water heater doesn't have to work so hard).
Guest (Peter)
If I understand the article correctly these types of panels will still transmit a broad range frequencies that the silicon cells can't use, in particular infrared, so there is a possibility that you could place these over a solar hot water system and have both working for you over the same area. That would take care of the cooling issue somewhat further.
Guest (tmk)
they are flat and concentrate light very well. can be made of plastic, etc.
Guest (Noah)
There are systems that use fresnel lenses. But they have the same disadvantages as regular lenses -- namely you have to track the sun accross the sky to focus the light. The holographic concentrators don't need to face directly toward the sun, so you don't need moving parts to rotate the solar panels.
Guest (SPO)
Re: why not use fresnel lenses?
1. Re-read the first paragraph of page 2 (lenses require sun-tracking and cooling systems).
2. Most plastics degrade quickly in direct sunlight.
Guest (HW)
Luminescent Solar Concentration
How would this method compare to other types of flat concentrators, e.g. Luminescent Solar Concentration, which has been around for many years?
Guest (Kamil)
Didn't Stanford Ovshinsky come up with a solar panel on stamped-steel that can withstand being shot with a .357 magnum without impacting on the device?
Guest (Bill)
Yes, they are the solar panels being sold by the company called Uni-Solar at http://www.uni-solar.com/ and they are made out of Stainless Steel... The military version that can take the bullets is here: http://www.uni-solar.com/interior.asp?id=103
Guest (NITIN BACHAL)
To reduce the cost of solar pv module the way is remove the si material from spv module and choose the new semiconductor material rather than concentrating and tracking dead investment and time.
Guest (PeterD)
Geez....yeah it would be a great idea to stop using the most abundant resource on our planet.
OK - who is for reducing purity requirements or improving the manufacturing process for raw silicon.....
many solar PV compamies are already reducing silicon use. One that I like is Evergreen Solar in the state of Mass. They already make very good panels using ribbon technolgy.
I don't wait for cheaper tech, I put my grid tied system in back in 2001 before incentives or even net-metering. I just added 4 evergreen panels in 2006 and love them.
Most panels today have warrenties for 25 years, don't use water or make pollution. They are cheap at $4 a watt, with incentive they are a steal.
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Guest (Sam DeLay)
Hail Stones
We had some as big as baseballs in Tennessee a couple of weeks ago. I hope this is sturdy. If plastic, I hope it does not break down in the sunlight.
Reply
Guest (D Van B)
Hail Stones
Same here in Indianapolis... busted a lot of windshields, dented metal... not sure if any solar system could survive that, though, so doubt it's a competetive disadvantage.
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Guest (T De W)
Hail Stones
Not many non-commercial systems would/could survive those direct hits.
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Guest (ken novak)
Most solar cells today face this issue, as they are encased in glass. The glass is specified to survive heavy storms, like car glass or skyscraper glass. It can break, but it takes a "disaster" level storm.
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Guest (DSMatthews)
Stainless Steel Mesh 1 or 2 feet above the glass
Just add a fine stainless steel mesh above the glass, it will deflect (bounce) or chop up and decelerate the incoming stones.
:-) Dan.
http://dan.3-e.net
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Guest (peter segaar)
steel mesh not a good idea
meshes will, whatever their diameter will be, shed linear shadows onto your photovoltaic material. Not a good idea. Power and energy loss will be dramatic, since it has been shown that linear shadows can dramatically reduce output of solar panels. Most dramatic certainly in systems with cells coupled into series and modules coupled into series.
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Guest (dsmatthews)
steel mesh not a good idea if thinck and close
Try a fine mesh up high and I thing in practice you may find that it works well enough and that there is not a sharp linear shadow cast from it.
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Coreyjacob
4 Comments
Re: steel mesh not a good idea if thinck and close
Any kind of mesh is going to reflect some sunlight away thus reducing the potential energy generated.
Maybe there is a process similar to bullet resistant glass that could be applied a 1/2 inch or so above the actual panel to reduce or eliminate the shock of the hail directly against the panel and to try to eliminate any deflection of the sun's rays.
By placing this bullet resistant like glass or plastic 1/2 inch or so away from panel would allow you to replace any cracked or damaged shields without having to replace the precious panel itself.
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Guest (Robert Loest)
Re: Hail Stones
The PV panels I've looked at (BP Solar, Kyocera, Sharpe) all are guaranteed against hail damage. They are also at an angle, which would reduce the impact of hail a good deal.
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Guest (Craig)
Hail Stones
I agree with Robert. I saw pictures from a guy in NM that had two cars ruined by baseball sized hail. He assumed his PV would be trashed, but it was totally fine...
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Guest (John Nicholson)
Hail
The ones stated have been tested up to 1.25 inch hail.
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Guest (Liang Ji)
Impact Test by UL
If the solar module bears UL1703 mark, it has been tested for an impact effect like following.
A module or panel is to be subjected to a 5 ft-lb (6.78 J) impact normal to the surface resulting from a 2-in (51-mm) diameter smooth steel sphere weighing 1.18 lb (535 g) falling through a distance of 51 in (1.295 m). The module or panel is to be struck at any point considered most vulnerable.
The pass criteria is that there shall be no accessible live parts, and breakage of the front material is acceptable provided there are no particles larger than 1 square in (6.5 cm2) released from their normal mounting position.
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