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Clear Solar Panels Double As Projection Screens
EnergyEfficient writes "Metropolis Magazine has an article about a company that is producing transparent solar panels. The panels 'can generate 3.8 watts of electricity per square foot, an above-average level of efficiency.' They come in a thick version that can be used for glazing buildings. Imagine if all those glass skyscrapers could also produce power! As an interesting aside, they can also be used as screens for projection TV units."
Let's take a super-skyscraper, assuming a 200' square base that's as high as the Sears tower (roughly 1450' to the roof top). Assuming the building maintains its rectangular cross section from the ground to the top gives us an area of 1.16 million square feet which would generate ~4.4 megwatts of electricity, which is a lot of electricity.
The article calls out a price of $45 per square foot, making the solar panels for such a building cost about $52 million dollars. Surprisingly cheap for that much electrical capacity, though the usage factor would be pretty low, what with it being dark at night and all.
"producing transparent solar panels."
"As an external glaze, PV-TV allows up to 10% visible light to be transmitted through the panel."
transparent Audio pronunciation of "transparent" ( P ) Pronunciation Key (trns-pârnt, -pr-)
adj.
1. Capable of transmitting light so that objects or images can be seen as if there were no intervening material. See Synonyms at clear.
For comparison purposes a typical power plant will produce on the order of 1000 Megawatts (some are more, some are less but that's a good ballpark). Such a solar panel clad building would produce a fair amount of electricity for a solar application, but it's still a miniscule amount compared to the power demands of even a small city.
" Wait, how much do the super-efficient panels cost? Oops..."
A.) Prices will go down if these things take off.
B.) Think of how much cheaper the electric bill will be. (Also consider how much more regular it has the potential to be.)
C.) Imagine if an ill-timed power outage wouldn't necessarily mean the building was affected.
I imagine once somebody sits down with a calculator and thinks out 5 to 10 years, the cost will end up being quite competitive AND they get bonus features to boot.
Just because something starts out at a high price doesn't always mean the value's not there, or that the price will always stay that way. The main reason I'm replying is not so much because of your particular comment, but because I've seen a great deal of sticker-shock on Slashdot without understanding some of these basic things about how technology economics works.
"Derp de derp."
My 110W panels are 4.3'x2.2' for 9.5 ft^2, that's around 11W/ft^2.
Maybe for amorphous it's high-efficiency, but compared to other technologies that's pretty low.
(Please check my math, I've been up for 2 days, and I'm old.)
I don't know where you got that idea.
White LEDs are less efficient than fluorescent lights.
Colored LEDs are quite efficient.
That's only if you used it one day and then threw it away. You need to divide by the number of days in use; if it lasted 10 years, that would come out to $1500/3650 = $.27/kwh. Of course, power inverters and storage would probably significantly increase the total cost above that.
As for ethanol, I will raise you Cornell study with this one from the USDA which seems to say that ethanol is energy positive.
http://www.windmeadow.com/
be lucky to get the things to last 5 years without breaking), then that momentary expenditure of oil will more than pay for itself.
Um, solar panels do in fact last that 20-30 years.
I don't care if it's 90,000 hectares. That lake was not my doing.
The article states that the factory where the glass is made is also the largest user of the glass:
The factory is now the world's largest single PV module plant, producing 100 megawatts of energy annually.
A megawatt isn't a unit of energy, it's a rate of transfer. Do they mean that it produces a continuous flow of 100 megawatts? If so, they would have to have 604 acres of glass (2.4 million of their 1m^2 panels). Of course you need to double that number because they're only collecting power half the day (generously assuming they're at peak output during all daylight hours)
On the other hand, if they're talking about generating 100 megawatt hours over the course of a year, then the plant is generating about 11,000 watts, or enough for about 10 average homes. By those numbers they'd have about 600 panels. That's a lot more reasonable.
Kevin Fox
Alright dude, but at the farms out here about 5 years is a good number, since these things are typically made of glass and, *surprise*, glass breaks. Last time I drove by a farm (about 5 weeks ago) about a third of the panels were broken-either from punks throwing rocks or just whatever. Just fragile, and that can be a pretty bad thing in the desert.
If my answers frighten you, stop asking scary questions.
Good point - however, most countries do not produce all of their energy with fossil fuels. Japan's electricity production is about 30% nuclear (the U.S. is running about 20%). Also, with something like this, you have to look at the marginal energy budget. Many buildings are already faced with glass which is an energy intensive material to make. The additional energy input needed to make these generate power is what needs to be compared against their output, not the total power to make the panels.
I think the question most businesses ask is how long will it take to get a return on investment.
The manufacturer specifies 38 W/m^2 or about 3.5 W/ft^2. Used as a window, the orientation would be fixed and I think you would be lucky to get four hours of good light to get something close to full efficiency.
So 3.5*4 = 14 Wh per day.
If electricity is 15 cents/kWh, you could buy 300 kWh for $45 (the cost per square foot of window).
To produce 300 kWh from a square foot of window would take 300 000/14 = 21 428 days or roughly 59 years.
Of course that doesn't take into account connecting your windows into the buildings power and the loss of effieciency there. And I also didn't take into account what the cost of regular windows are to begin with, since that should be reduced from the price, but I would guess they would be a few dollars and might take 10 years off the total.
Once electricy prices increase to $1.50/kWh these babies should be selling like hotcakes.
purves
Granted this might not be the most disinterested source in the world, but it goes along with most of the studies I've seen over the years. I'd be interested in seeing any recent studies that show solar cells taking more energy to build than they generate.
2) The specific cells referred to in this thread are not particularly efficient. A little back-of-the envelope calculation says that they are approximately 3.6% efficient. A typical single crystal array would be over 15% efficient, and amorphous silicon can often hit 7 or 8% (more in the lab). Of course that's not surprising in solar cell you can see through.
Don't forget that the sun won't hit all 4 sides of the bulding. With the angle of incomming light, and the position of the sun during the day/season, you'd be lucky to get even a third of your calculated total electricity produced.
My Kyocera KC120 panels produce 12 watts per square foot, 3.8 doesn't sound above average to me.
3.8 Watts per square foot is a joke. Your average silicon panel (~10% conversion efficiency) is 4 times more efficient. Triple junction panels are 3 times better than that.
http://jsl.com/solar
> 175*600*4*45 = $18900000
In the Northern hemisphere, you'd only put solar panels on the South face of the building.
At most, only the South/East/West faces of the building.
If the building is not square to North (IE, the
faces of the building are NE, SE, SW, NW), then
you'd put solar panales on the SE and SW faces.
Polycrystalline cells don't have this problem, and I can buy top shelf "BP Solar" branded cells with a 20 year warranty! Similar $/Watt too. What does this mean for the MSK-clad building? Will its enviro-friendliness fade? And what effect does age have on its transparency/opacity?
This two page .pdf provides additional and larger images. You can clearly see the etching and degree of tint. It also includes tables of electrical and mechanical specs.
If we knew what we were doing, it wouldn't be called research, would it? ~ Albert Einstein
In comparison, the major generators in Victoria, Australia, Loy Yang, a set of brown coal burning power plants, produces 500 MW per station, for a total of 2 GW. I somehow doubt that a building can produce even one fifth of that, no matter the size of the building and the number of panels that may be put in as windows.
Let's see. A map of solar energy falling on the US suggests up to about 3000 (let's overestimate) BTU per square foot per day. That is, armound three million joules per square foot per day. That's around 35 watts per square foot. 100 megawatts is about three _million_ times that. So you're looking at a bit over 275,000 square metres to generate 100 MW of power from solar. That's a square, about 525 metres by 525 metres. And those figures are based upon horizontal facing.
Looks like somebody got some units incorrect...
And how much energy does it take to produce a single square foot. There is a basic falicy that a lot of folks seem to miss ... The same thing holds for all current forms of solar energy.
Actually, this is a basic falacy that you have missed. While what you say is true for ethanol, it is not true for modern photovoltaics (and hasn't been for some time). As for photothermal, you are also dead wrong.
$45 per square foot according to the linked page. That's less than $12 per peak watt. It's easy to spend more than that for conventional solar panels, though reasonably careful shopping will get you to the $6-7/watt range and Froogle showed one for $4.70/watt.
Do all four sides of the sears tower get direct sunlight? How many hours of full sunlight? The generating numbers for photovoltaic panels are always full sunlight output. Notice in the article how only the top and one side (the south side in the nothern hemisphere) is clad. Aiming photovoltaics east or west or north is not cost effective.
I gotta look at my 165 W sharps which are about 8sq feet and wonder at that. But my panels are not clear. Which is a plus as the also shade the roof and make that part of the house cooler. (if only they had 1/2" pipes wired under them so I could water cool them and run the warmed water into a tank).
And yes, the windows are mounted vertically. In math, that's at 90 degrees.
The ideal mounting angle is your latitude (eg the Bay Area and DC are around 37 degrees).
So these will be most efficient at Sunrise/Sunset. When the sun is at its weakest (lots of atmosphere to get through).
On the other hand, if they are good projection screens, you aim your projector at it, that causes it to generate power which you can use to plug the projector into!! Perpetual energy!!!
or something.
Bottom line:
If they work and don't cost a lot more than regular windows (such that in 10 years they save more in power costs than they cost), then great!
If every house with a decent roof exposure between 10 and 3 has even 4 solar panels on and generated even 20% of their own power, and there was enough to knock 5% of power use down in our country (world?), then it's a win.
There's no need to "go off grid" and raise your own goats for food and knit you're own underwear to use solar.
(Now, if you switch from CRT to LCD, you save having to buy $500 of solar panels...)
Just to note, an average coal plant releases 88 pounds of uranium into the air a day. So, nuclear is much cleaner than coal. :-)
Hurricane Ivan: A 17th century prison collapsed. All of the inmates escaped.
Not that I'm a consipracy theorist or anything, but of course it does. That is the US Department of Agriculture after all. And we're talking about what? Corn ethanol? Hmm, corn is an agricultural crop.
Now, take a look at the first two bullet items from their mission statement:
Do you honestly think they'd ruin a perfectly good opportunity for one of the largest food crops in the US by speaking badly of corn derived ethanol? Please...
> Like the fact that you burn more oil to create an equivianent amount of ethanol from corn.
this is myth. Don't be misled by the oil industry.
You also miss the point that growing biomass pulls CO2 out of the atmosphere -- more CO2 remains locked in the roots etc than is released by buring the produced ethanol.
Further, after getting ethanol from the corn, the remainder is MORE suitable for cattle feed than corn. A big proportion of corn grown in the US is used for feed, but cattle digestion is better suited to cellulose (what's left after ethanol extraction) than to starch (corn).
AND, extra bonus, cattle on a cellulose diet give off less methane (which as you likely know is another potent greenhouse gas)
There are better biomasses to grow than corn, though; many interesting improvements to make there.
Archer McDaniels Midland are going into corn-to-ethanol in a big way, because it's such a synergistic process.
Most current solar panel designs (i.e. not the new ones not yet in production that are a bit more efficient) generate energy output equivalent to the input needed to create them in about 5 years. Given a projected panel lifetime of around 20 years conventional panels are a good investment from that point of view, although there are some concerns with some designs about disposal.
If the clear panels can recover the energy input in around the same time period compared to the energy input of a solar panel AND a window (since they will be doing both jobs) then it seems a good tradeoff.
Also clear solar panels are useful given that you are likely to have windows in your house anyway. It also means that there isn't really a problem with planning permission as your house won't look any different. In addition it means you can have solar panels as windows AND on your roof, in theory.
Still I think a big gain would be in designing new house production to be energy efficient from the outset - thick, well insulated walls, etc.
Even so, a great way of absorbing some spurious solar energy instead of dumping it as heat, or reflecting it to annoy someone else, as the adhesive plastic films do.
The challenge will be to orient buildings properly for maximum energy, some interesting, and possibly movable, architectural features might result!
http://yarchive.net/nuke/coal_radiation.html
The best one: http://www.ornl.gov/info/ornlreview/rev26-34/text/ colmain.html
Hurricane Ivan: A 17th century prison collapsed. All of the inmates escaped.
Architects and engineers are looking into ways to make building more efficient. (Sometimes the clients request it, sometimes they sell it to them based on calculations of cost over the life of the building)
William McDonough: he is a leader in the field and has been influencing other high profile architects to include exactly those kinds of features into new construction. Along with passive heating and cooling and natural lighting.
Some recent projects that do not fit the stereotype of sustainable or green building include 4 Times Square (skyscaper) by Fox and Fowle and the David L Lawrence Convention Center by Rafael Vinoly.
"I'm an indescribable shade of twilight...Any second now I going to turn myself off"