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## Clear Solar Panels Double As Projection Screens304

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."
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## Clear Solar Panels Double As Projection Screens

• #### Wonder if they are more efficient... (Score:3, Insightful)

on Saturday August 07, 2004 @09:10PM (#9911140) Homepage
Wonder if they are more efficient than the solar panels mentioned in a previous /. story?
• #### Re:Wonder if they are more efficient... (Score:5, Informative)

on Sunday August 08, 2004 @01:46AM (#9912026)
They say "PV-TV can generate 3.8 watts of electricity per square foot, an above-average level of efficiency"

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...)

• #### Re:Wonder if they are more efficient... (Score:3, Informative)

I seem to remember that when the sun is overhead in a clear sky the power density is about 1400 watts per square metre, which makes the efficiency about 3%, which is not bad for large-area, inexpensive, transparent cells, but nowhere near the 20% or more of a good conventional cell (your Sharps are getting about 16% which is OK, some will be lost in the control circuits, blocking diode, etc, if they are wired for battery charging). But remember, this is transparent to it has only the light it absorbs to wor
• #### Cool! (Score:3, Insightful)

on Saturday August 07, 2004 @09:12PM (#9911148)
It's nice to see that projection technology will be getting cheaper, what with the integrated solar panels and all. Wait, how much do the super-efficient panels cost? Oops...
• #### Re:Cool! (Score:3, Insightful)

If you are getting the building cladding as well as the PV units in the one unit, the cost equation looks even better. I don't know what normal 13mm glass might cost, but figure it is fairly expensive in itself. The TCO of these things might not be that bad after all?
• #### Re:Cool! (Score:5, Informative)

on Saturday August 07, 2004 @09:46PM (#9911275) Homepage Journal
" 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.
• #### Re:Cool! (Score:3, Insightful)

You make a good point, but here's a few more things to consider that many people forget to figure in the equation.

* These can never be cheaper than plain glass, because no matter how far the price drops you can always build the same thing minus the solar collector and get it even cheaper

* When you spend more money to save in the long run, you are judging a present value versus multiple future values. To get an accurate number you need to take the initial price difference of the inefficient model and the e
• #### how much do the super-efficient panels cost? (Score:3, Informative)

\$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.
• #### Brainstorm (Score:5, Funny)

on Saturday August 07, 2004 @09:15PM (#9911157)
"I know, we'll make a solar panel that lets the light just go right through it! What a great idea!
• #### No Dumbass (Score:5, Funny)

on Saturday August 07, 2004 @09:28PM (#9911212)
The point is that you can use it with projector TVs. The light from the projector creates the power to run the projector, duh! I'm running over to walmart to buy one for my for my fan powered sailboat right now.
• #### Re:Brainstorm (Score:2)

Well, yeah. If there's no light inside, how are you going to operate your solar-powered flashlight?
• #### Does it play d00m? (Score:3, Funny)

on Saturday August 07, 2004 @09:15PM (#9911160)
This amorphous silicon technology has a three-in-one functionality: it is able to act as a glazing element, solar panel, and video display screen.
Those Japanese think of everything - a video screen that generates it own power & keeps the rain out!
• #### How much does it cost (Score:4, Insightful)

on Saturday August 07, 2004 @09:16PM (#9911162) Homepage
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. Like the fact that you burn more oil to create an equivianent amount of ethanol from corn. There is a study [cornell.edu] at cornell that shows this. The same thing holds for all current forms of solar energy. While it will no double have niche applications, it's not going to release the world from dependence on oil, even if we could plater all the skyscrapers of the world with it.
• #### Re:How much does it cost (Score:5, Insightful)

<moonbender@gmail ... minus physicist> on Saturday August 07, 2004 @09:24PM (#9911199)
And how much energy does it take to produce a single square foot.

Actually, the question should probably be: How much energy does it take to produce a square foot compared to a square foot of glass? But the question probably isn't even relevant, I'm sure the price will be prohibitive anyway, at least for mass adoption. In general, you're right, of course: this "ecological backpack" is an important issue the public really isn't aware of.
• #### Re:How much does it cost (Score:5, Interesting)

on Saturday August 07, 2004 @09:49PM (#9911288) Journal
The evaluation requires multiple points before you can determine worth:

1) How much does it cost to produce a square foot of this solar panel?

2) Same question as #1 for the glass that would be used normally?

3) How much energy will this solar panel -leak- over the expected life span of the installation?

4) Same as #3 for regular glass?

5) What is the energy gained by the solar collection process?

6) After all factors considered, is the cost of the solar panel compared to regular glass over the lifespan of both higher (bad) or lower (good)?

Illustration (all assumptions):

* Assume the installation has an expected life span of 10 years (I would hope the lifespan of skyscraper glass would be more like 40-50 years or more, but that is a pain to calculate).

* Assume that the glass installation costs \$1,000 (we're talking a big piece of skyscraper glass here, ok?)

* Assume solar panel costs 10x the normal glass installation, \$10,000

* Assume that each year the regular glass will cost 1/2 again the initial cost in energy loss (probably a pretty drastic assumption but it makes things easy) ... \$500/year

* Assume that each year the solar glass will net 1/2 again the initial cost of -regular- glass each year (another drastic assumption) ... \$500/year ... that net meaning that it paid for the energy lost through it and had dividend above that mark (ok, so extremely drastic)

Factored together, after 10 years the regular glass net cost was \$6,000 whereas the solar glass net cost was \$5,000 (and also helped subsidize the cost, making future installations less costly).

Of course, being assumptions you could easily make an example where the reverse was true and the solar glass was more expensive over 10 years (again, hoping that 10 years is a small chunk of the real installation).

My point is pretty small for all of the above ... that ecological costing is actually fairly complex and is why the public often doesn't "get it". Maybe we need to go to the utility model for things such as this as well. That is only partial sarcasm, BTW, it could actually make a lot of sense to figure out a model whereby such things could be scaled out over time so that the initial aquisition was not prohibitive.

• #### Re:How much does it cost (Score:3, Insightful)

Don't forget to put in discount factors for future costs of electricity, growing demands on the local grid from other development, and utility of having an independent power source in the event of generation plant or transmission line failure.
• #### Re:How much does it cost (Score:2)

Since these panels also function as digital displays, they probably are not cost effective unless you really WANT a display (for advertising, I guess).

If they catch on enough, a cheaper non-display version could along in the future, once the economy of scale kicks in.
• #### Re:How much does it cost (Score:5, Insightful)

<.moc.oohay. .ta. .ruai-setirdnamihcra.> on Saturday August 07, 2004 @09:34PM (#9911233)
But there is something. If solar panels could have a lifetime of about 20-30 years of use (right now you'd be lucky to get the things to last 5 years without breaking), then that momentary expenditure of oil will more than pay for itself. It would be better to spend that oil on making efficient solar panels than to burn it in an SUV. No, we're not there yet and we're probably a good decade off, but the only way to improve this is to keep refining the fabrication process.

Solar is attractive because it isn't seasonal (unlike hydroelectric, which is only available during a portion of the year and is usually unavailable during the time we need it most, summer). Solar is unsightly and takes up a lot of real estate, which makes local environmental lobbyists pissed, but where I live (Southern California), it makes sense because we have a perfectly good desert nearby and placing a solar panel farm out there is simple Trying to place one in downtown Chicago is made easier by the panels in this story, since they could be incorporated into most buildings that have a modern, glass-heavy look. But the problem there is that Chicago and many other urban cities don't get nearly enough sunlight to make a panel farm efficient, just like most most areas don't get enough wind to make a propellor farm efficient. Better panels may come along, but there will always be cities that have to rely on other forms of power (nuclear comes to mind, and maybe someday we'll get fission to work-bring on the Duke Nukem Forever jokes).

As for corn ethanol, not only is it wasteful of energy, it's typically more expensive than your average gallon of gas here in the United States. Have to agree with you there.

The trick is that you have to look at solar from a few angles. It isn't a cure all for our energy problems, but it has more than just a few 'niche' applications and it could help make a serious contribution once the technology has matured.

Wow, did I really write all of that?
• #### Re:How much does it cost (Score:2)

Solar is attractive because it isn't seasonal

Hmm, I don't think they'll buy that argument in northern Europe or Alaska. (But I agree with the point for most of the world's highly populated areas.)

• #### Re:How much does it cost (Score:5, Informative)

on Saturday August 07, 2004 @10:15PM (#9911374) Homepage
If solar panels could have a lifetime of about 20-30 years of use (right now you'd
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. [solarbuzz.com]

• #### Re:How much does it cost (Score:3, Informative)

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.
• #### Re:How much does it cost (Score:3, Insightful)

Yah, but this stuff would be attached to buildings in a city mostly. I think the windows on the average skyscraper last more than 5 years without somebody throwing a rock through them (or even a jet plane)
• #### Re:How much does it cost (Score:2)

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.

Thats easily fixed. Simply wire the power outflow through the fence around the solar farm. Should keep most of those punk vandals from damaging the cells.
• #### Re:How much does it cost (Score:2)

Not that I don't believe you or anything, but I don't believe you. Solar panels are not fragile. They're designed to withstand quite a bit of punishment, typically with a nice layer of high temper (ie: bullet proof) glass over the panels.

• #### Re:How much does it cost (Score:5, Interesting)

on Saturday August 07, 2004 @10:23PM (#9911399) Homepage
Solar is attractive because it isn't seasonal (unlike hydroelectric, which is only available during a portion of the year and is usually unavailable during the time we need it most, summer)

Kind of the opposite here in Ontario. The length of time the sun is out changes a lot. On June 20th of this year, the sun rose at 5:45am and set at 9:07pm (at my location of course). On December 20th of this year, the sun will rise at 7:52am and set at 4:52pm. The further north you go, the more drastic the changes.

Solar power should work out reasonably well even with those changes in daylight hours because peak electric use is during the summer where the most power is used.

Why is hydroelectric generation seasonal? It's my understanding that most of our hydro is generated using dams. Some is generated on rivers such as the Niagara River. Do your rivers dry up in the summer or something?
• #### Re:How much does it cost (Score:2)

Yep, in California the rivers don't run very well during the summer/fall. So the amount of electricity they produce in that time period is a trickle, and in the summer, when everyone is running air conditioners, we tend to be susceptible to power shortages.
• #### Re:How much does it cost (Score:2, Insightful)

maybe someday we'll get fission

Yes, in the far-off future world of the 1960s, we and our descentants will live on a world powered by the mysterious atom! You can ride an atomic-powered sidewalk to the nuclear air-depot, catching a 5-minute ride to Bangladesh on the world-wide nuclear shuttle. Energy will be cheap and reliable in this spectacular future, brought to you by the scientists at General Atomics!
• #### Re:How much does it cost (Score:2)

Terribly sorry, meant fusion of course. As for fission, my memory seems to recall the first civilian power station (Shippingport, brought to you by Admiral Rockover) as being built in the 50s (Google leads me to say 1958). Simple PWR reactors are still working hard for us, but there haven't been built recently, and if the present situation continues, there won't be any more built in the US. Period.
• #### Re:How much does it cost (Score:2)

hydroelectric [...] is usually unavailable during the time we need it most, summer

I can tell you're a southerner :).

• #### Re:How much does it cost (Score:2)

which makes local environmental lobbyists pissed, but where I live (Southern California), it makes sense because we have a perfectly good desert nearby and placing a solar panel farm out there is simple

I call NIMBY! Would people in forested regions care if we leveled a couple acres to put up solar panels (or those folk in Nanntuket with the wind farm)? I'm sure they would. Now why would paving over a perfectly good desert with them be any different?

I've lived my whole life in the desert (South/Central
• #### Re:How much does it cost (Score:2)

err... I meant northern AZ and NM...

WHY CAN'T I EDIT MY POSTS! My life is too fast and.. er... I'm too lazy to preview...
• #### Re:How much does it cost (Score:4, Insightful)

on Saturday August 07, 2004 @09:43PM (#9911262) Homepage
The fallacy that you refer to doesn't apply to solar panels in quite the same way as it does to ethanol. The question needs to be something more like "what is the ratio of (power produced per sq ft)*(lifetime of a sq ft)/(energy required to create square foot)?" So long as that ratio is greater than 1 there will be a net gain in energy.
• #### Re:How much does it cost (Score:2)

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.

This is a good point.

At the same time, though, solar cells last up to about 30 years. So in a way, a solar cell is like a 30 year battery. There may be situations in which bying cheap energy now and "storing" it in a solar cell for 30 years might by less expensive in the long run. They would in effect grabbing more cheap energy early while others have to buy more expensive energy la
• #### Re:How much does it cost (Score:2)

"While it will no double have niche applications, it's not going to release the world from dependence on oil..."

Yet. Technology only gets better. Say a minor tweak to the process makes a solar panel last twice as long. That's half the resources to make one panel, right?

It's not so much that it's a falicy, it's that the game isn't over yet.
• #### Re:How much does it cost (Score:3, Interesting)

The same thing holds for all current forms of solar energy.

Not true. Both hydroelectric and wind are basically solar-powered. And neither of those have much in the way of a set lifetime, nor do they take large amounts of energy to develop.

There are also solar powerplants that use large arrays of mirrors to boil water into steam and run turbines. Again, I don't see these having any specific lifetime so there isn't any cost of recreation, just maintenance (which should be small)

As far as I know, it's basi
• #### Re:How much does it cost (Score:5, Informative)

on Saturday August 07, 2004 @10:11PM (#9911353) Homepage
Either you are misinformed or you just like to spread FUD. According to the Department of Energy [energy.gov] Studies have shown that, depending on the type of PV technology, the clean energy payback of a PV system ranges from one to four years.

As for ethanol, I will raise you Cornell study with this one from the USDA [usda.gov] which seems to say that ethanol is energy positive.

• #### USDA Study? (Score:4, Informative)

on Sunday August 08, 2004 @03:15AM (#9912175)
...this one from the USDA which seems to say that ethanol is energy positive.

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 [usda.gov]:

• Expand markets for agricultural products and support international economic development;
• Further develop alternative markets for agricultural products and activities;

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...

• #### Re:How much does it cost (Score:4, Interesting)

on Saturday August 07, 2004 @10:12PM (#9911354) Homepage
Congratulations, you've discovered the second law of thermodynamics!

You know what will release the world from dependence on oil? The oil running out. The only question is, will the replacement energy technology be ready by then, or will we be caught unprepared and reduced to Mad Max style barbarism for a few centuries?

• #### Re:How much does it cost (Score:3, Informative)

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.
• #### In 59 years it will pay for itself. (Score:3, Informative)

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

• #### Re:How much does it cost (Score:2)

While you are correct regarding ethanol, you are in error about solar power. It takes a typical solar panel roughly three years of production to pay back the energy it took to create. That isn't good, but its hardly as bad as ethanol. After three years you see a net power gain.

The main expense (in terms of energy) in producing solar panels is the silicon wafer that most commercial panels are based on. A company called Astropower (now defunct) recycled flawed wafers from chip manufacturers. That cut t

• #### Re:How much does it cost (ot: ethanol vs gasoline) (Score:2)

Like the fact that you burn more oil to create an equivianent amount of ethanol from corn.

The story [cornell.edu] you cite does not show this.

An acre of U.S. corn yields about 7,110 pounds of corn for processing into 328 gallons of ethanol. But planting, growing and harvesting that much corn requires about 140 gallons of fossil fuels and costs \$347 per acre, according to Pimentel's analysis. Thus, even before corn is converted to ethanol, the feedstock costs \$1.05 per gallon of ethanol.

• #### Re:How much does it cost (Score:4, Informative)

on Sunday August 08, 2004 @01:02AM (#9911930) Homepage

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). [nrel.gov] As for photothermal, you are also dead wrong. [ecovillage.org]

• #### Is it cost effective? (Score:2)

From the article: "One stumbling block is how difficult it is to quantify the product's value versus its price. (Right now, the technology is priced at \$45 per square foot.)"
• #### Not really... (Score:2)

My electricity runs about \$0.08 per kilowatt-hour. A 1 square foot panel would produce 3.8 Watts X 8 hours (assuming 8 good hours of sunlight) or ~ .03 kW-hr at a cost of \$45, which works out to \$1500 per kilowatt hour. Cheap for solar, owing to the higher efficiency of the panels, but dismal by commercial generation.
• #### Re:Not really... (Score:2, Informative)

A 1 square foot panel would produce 3.8 Watts X 8 hours (assuming 8 good hours of sunlight) or ~ .03 kW-hr at a cost of \$45, which works out to \$1500 per kilowatt hour.

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.

• #### Yeah I should have put that in there... (Score:2)

The payoff time is very long... after a couple of decades you'll be beating the power company, but there's a hell of a lot better way to invest your money :-)
• #### Re:Not really... (Score:2)

Maybe I'm missing something obvious, but that's only \$1500 kW/h on the first day.

Assuming it lasts more then a day, wouldn't the effective \$ per kW/h price drop over time?
• #### Re:Not really... (Score:2)

Doesn't that only apply if you then take the panels down after the first day?

These things get cheaper the longer you use them, so it'll be .03kw-hr per day...Want your kw-hr to be \$5.00? Use your panels for...umm....okay- its probably a long time, but you get the idea- do the math.
• #### Re:Is it cost effective? (Score:2)

"From the article: "One stumbling block is how difficult it is to quantify the products value versus its price. (Right now, the technology is priced at \$45 per square foot.)"

I think the point was that there are other benefits to this type of power. If, for example, these panels charged a battery that a house or building ran on, then you'd have a form of UPS in the event of a power failure. How much is that worth? Etc.
• #### Re:Is it cost effective? (Score:2)

We have several solar panels we use where I work and the things have to be cleaned fairly regularly to get full efficiency out of them. So don't forget to factor in the cost of labor to clean the roof of a large building that has these things.

My question is... how many kilowatts of electricity is used to produce each square foot? I'm sure it probably exeeds the ammount of energy these things produce for at least 10 years.
• #### How good of a projection surface is this? (Score:2)

I wonder how great of a project surface this really is. They say it can be projected on from either the inside or outside, meaning that the surface is really reflective. But they say in the article:

"Since the PV-TV screens don't have the luminosity of liquid crystalline or a digital TV screen, they perform best when there are no other competing light sources, according to MSK spokeswoman Aya Tanida."

That means you can only use it in the dark? i.e. nighttime?

Also if it's really reflective, isn't that goin
• #### Fantastic (Score:5, Interesting)

<bigberk@users.pc9.org> on Saturday August 07, 2004 @09:28PM (#9911213)
There are lots of interesting things that could be done to produce more ecologically friendly buildings.

The first is simply to make more efficient use of natural light! I stayed for a week in a new residence building at The University of East Anglia [uea.ac.uk] (Norwich, UK) and the building really intrigued me. It had hollow lighting columns running up to the top of the building, despite being a rather tall apartment. So there was natural light from the top reaching all floors. That definitely saves lighting costs.

So with approaches like that (using natural light as much as you can) coupled with clear solar panels, you could both use natural lighting and collect power for electrical lighting later on. Improve actual lighting with high-efficiency (85% +) white LEDs (last forever) or high efficiency fluorescents, and you've got one amazing power-efficient building.

The problem is that these supplies -- solar panels, white LEDs have large initial costs. As these costs come down we'll see lots of nice new interiors. I can only expect such things to become more common as people actually realized they're screwed for cheap power.
• #### Re:Fantastic (Score:4, Funny)

on Saturday August 07, 2004 @09:54PM (#9911300) Homepage Journal
"The first is simply to make more efficient use of natural light!"

Heh. Where I work, our computer screens light the room.
• #### white LEDs are not 85% efficient (Score:2, Informative)

by Anonymous Coward
I don't know where you got that idea.

White LEDs are less efficient than fluorescent lights.

Colored LEDs are quite efficient.
• #### Re:white LEDs are not 85% efficient (Score:2)

White LEDs are less efficient than fluorescent lights. Colored LEDs are quite efficient.
Sorry, you are right. White LEDs are currently not as efficient in lumens/watt than the higher efficiency fluroescent lighting systems. Perhaps that high % efficiency figure in my head was for red LEDs or something.
• #### Re:Fantastic (Score:5, Interesting)

on Saturday August 07, 2004 @10:02PM (#9911325)
Like transparent concrete? http://optics.org/articles/news/10/3/10/1 [optics.org]
• #### Re:Fantastic (Score:2)

Nah ... I'm holding out for Transparent Aluminum.
• #### How much power would that be? And at what cost? (Score:5, Informative)

on Saturday August 07, 2004 @09:33PM (#9911227)
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.
• #### Replying to my own post... tsk tsk... (Score:3, Informative)

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.
• #### Re:Replying to my own post... tsk tsk... (Score:5, Interesting)

on Sunday August 08, 2004 @12:49AM (#9911893) Homepage
While it may be miniscule for a city, would a Sears Tower application, generating 4.2 Megawats, be able to power the building itself? I wonder what the average consumption of the Sears Tower is?

Of the Gigawatt produced by a power plant, how much of it is lost to power transmission? I mean, if these powerplant-esque high rises are closer to the point of consumption, aren't they a tad more efficient than the traditional at-a-distance power plants?
• #### Re:How much power would that be? And at what cost? (Score:4, Informative)

on Sunday August 08, 2004 @01:17AM (#9911974) Homepage
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.
• #### Re:How much power would that be? And at what cost? (Score:4, Insightful)

<eivindorama@gmail.com> on Sunday August 08, 2004 @04:49AM (#9912353) Homepage
It's probably not very realistic to calculate as if the sun is shining straigth-on on all 4 sides of a skyscraper at once...

• #### Ummm... (Score:5, Informative)

on Saturday August 07, 2004 @09:34PM (#9911229)
"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-)

1. Capable of transmitting light so that objects or images can be seen as if there were no intervening material. See Synonyms at clear.
• #### Re:Ummm... (Score:4, Informative)

on Saturday August 07, 2004 @10:25PM (#9911403) Homepage Journal
Consider the window film that reduces the amount of light passing through a window, but allows for a clear image through the glass. That is "transparent", even though it is not passing all the light.

"Translucent" means that while some qunatity of light is allowed to pass, no meaningful image passes.

So it is possible to be both transparent and yet block some of the light - and for an example look no furthur than your sunglasses.
• #### ...can generate 3.8 watts of electricity... (Score:4, Funny)

on Saturday August 07, 2004 @09:39PM (#9911253) Journal
Gee, imagine what they could do with OPAQUE ones!

• #### 3.8 watts per square foot with what? (Score:3, Interesting)

<markt@NoSPaM.nerdflat.com> on Saturday August 07, 2004 @09:44PM (#9911265) Journal

Bright sunlight, regardless of angle?

Diffused light on a cloudy day?

In outer space, facing the sun?

They say absolutely nothing about the preconditions that are necessary to produce that 3.8 watts... and it's simply not possible for it to produce the same output regardless of its environment.

• #### Um.... (Score:4, Insightful)

on Saturday August 07, 2004 @09:46PM (#9911279)
Has anybody considered that most skyscrapers are surrounded by -other- skyscrapers? Kind of cuts down on the whole direct sunlight thing......
• #### Mega-whats? (Score:5, Informative)

on Saturday August 07, 2004 @10:20PM (#9911390) Homepage
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 [google.com] (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 [google.com]. That's a lot more reasonable.
• #### Wait a minute here.... (Score:5, Funny)

on Saturday August 07, 2004 @10:22PM (#9911394) Homepage Journal
Are you saying that ALL computers, including the Linux boxes will be powered by Windows.

Arrrrgggghhhhhhh

• #### Junk the TV part of it.. (Score:2)

And give us intergrated LCD shutters.

"But PV-TV's most unusual feature is its ability to act as a full-color internal and external screen. A picture or advertisement projected from inside a structure can be seen within that building, with PV-TV acting as a regular display screen. On the outside of the building, the material can function as a giant billboard."

Am I the only one who is getting really fed up with the ever-increasing advertising going on? This might be a fantastic invention--certainly it sounds very innovative--but if they are

• #### Above average? (Score:5, Informative)

on Saturday August 07, 2004 @10:58PM (#9911514) Homepage
3.8 watts of electricity per square foot, an above-average level of efficiency

My Kyocera KC120 panels produce 12 watts per square foot, 3.8 doesn't sound above average to me.

• #### Something is bogus (Score:5, Informative)

on Saturday August 07, 2004 @11:04PM (#9911530)
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
• #### What's the lifespan of these panels? (Score:3, Informative)

on Saturday August 07, 2004 @11:41PM (#9911659)
Solar cells using amorphous silicon technology have a limited lifespan, so they generally carry a 12 month warranty. At least at http://www.jaycar.com.au/ [jaycar.com.au] where I buy stuff. Their output decays with age and within 5-10 years they can have the same PV properties as brick/mortar cells.

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?

• #### Additional Info (Score:2, Informative)

This two page .pdf [msk.ne.jp] provides additional and larger images. You can clearly see the etching and degree of tint. It also includes tables of electrical and mechanical specs.

• #### What about hybrid cars? (Score:2, Insightful)

Seems to me the most useful application would be in car glass for gas/electric hybrids. The power generated by the clear solar panels would go into the cars electric propulsion system when it is running and trickle-charge the batteries when sitting out in the parking lot.

Hey, who knows. Maybe one day drivers trying to park in parking decks will fight over top-level spaces to get their batteries charged.

theDunedan
• #### Ah, I see (Score:5, Interesting)

on Sunday August 08, 2004 @12:58AM (#9911920) Homepage Journal
At first, I read it as 3.8kW and said, "Hunh? That's more than the Solar Constant, 1.367kW per square meter." Then I reread it and saw that it was simply 3.8W. This sounded much more reasonable... and small.

This means that a 60W light bulb would need almost 16 square feet to function. Well, that of course is a reason to move to compact flourescents or LED light bulbs. But my computer takes up a bit of power. So does a refridgerator. So does a washer/dryer.

Let's say that it is a television. What's the equivalent of a square foot display (asuming a 5:4 ratio)? About 13"? Can a 13" LCD display work with 3.8W of power? (I don't know. That's why I'm asking.)

I'm not questioning whether it can give power. I'm questioning whether it can give sufficient power to offset the price. Or would the money be better spent elsewhere in green technologies to reduce the actual draw from the grid?
• #### Re:Ah, I see (Score:3, Insightful)

At first, I read it as 3.8kW and said, "Hunh? That's more than the Solar Constant, 1.367kW per square meter." Then I reread it and saw that it was simply 3.8W. This sounded much more reasonable... and small.

This means that a 60W light bulb would need almost 16 square feet to function. Well, that of course is a reason to move to compact flourescents or LED light bulbs. But my computer takes up a bit of power. So does a refridgerator. So does a washer/dryer.

Moving to LEDs will cut prices drastically. The
• #### Money (Score:3, Insightful)

Unless there is a case where someone has an overabundance of money, choices and compromises must be made. It's like when you have to pay \$800 in rent, but you only have \$500 in the bank account. It doesn't matter how nice that apartment is or how close it is to work.

So for \$45 * 95 square feet, you can run the VOS Pad LEDs. Of course, I acknowledge that you pointed out that this is when all lights are on full. What you failed to mention was that the VOS Pad costs £35,000 (about US\$52,500). This
• #### just cause (Score:4, Funny)

on Sunday August 08, 2004 @02:32AM (#9912114)
Why don't we just install a "Spaceballs" style solar glass enclosure around the earth at 26000 miles from the center? Just high enough to keep the geostationary satellites inside (wouldn't want to lose our tv). The surface area should be about.

131,657,416,704,000,000 sq/ft

and cost

\$5,924,583,751,680,000,000

in raw materials (maybe we could get a bulk discount)
we should also try to cash in on a "free installation"

The output of such a sphere would be

500,298,183,475,200,000 watts continuous

Or (for sake of easier calculation in an already complicated process) if only half of the sphere received light at any given time

250,149,091,737,600,000 watts continuous
250,149,091,737.6 kW continuous
250.15 Petawatt continuous

Power demand in 2002 for the entire world
13,747,393,531.8 kW continuous
0.0137474 Petawatt continuous

sure every living thing on earth would probably die and we would enter a perpetual ice age from the lack of light and heat but, you could throw away the sunscreen and with all that extra energy maybe we could string up some halogens or something along the inside! We could also sell advertising space on it.

All conversions made with http://www.onlineconversion.com/ [onlineconversion.com]
Power consumption data from http://www.eia.doe.gov/emeu/international/total.ht ml#IntlConsumption [doe.gov]
Geostationary orbit data from how http://octopus.gma.org/surfing/imaging/howhigh.htm l [gma.org]
Radius of the earth from http://www.page.sannet.ne.jp/ikenoue/e-mode/earth. html [sannet.ne.jp] (seems accurate)
Output and cost from RFTA

If you think that my math is wrong then check and let me know, too tired to think anymore.

• #### I find it irresponsible of the construction & (Score:3, Interesting)

on Sunday August 08, 2004 @07:46AM (#9912662) Journal
... industries for NOT using power reclemation and "free source" power generation (wind, solar, brake regenerative)

I wonder if there will be any cities that will ever require buildings to have such technologies in the new construction, just as say Germantown Tenneesee requires no backlit signs above a certain height and at that can't diplay food items. They also have restrictions about trees and shrubs having to be every few feet in a parking lot and cobble stone or brick pavers instead of concrete or black tar paving.

Reclamation and regeration could EASILY revoltionalize the tax system in my opinion. One of the number one costs to most cities is paying for the power for stoplights, government buildings, and sign illumination. If this cost were significantly reduced or eliminated, it could be extra money in the taxpayers hands and therefore less tax increases or maybe even a rollback.

• #### Stop bitching about the inefficiency! (Score:3, Insightful)

on Sunday August 08, 2004 @10:20PM (#9917075)
This is revolutionary because it nows allows solar panel installation in a place where no one could before: on windows. I don't understand all the bitching about the panel's inefficiency. The panel is a compromise, if anyone read their website [msk.ne.jp], they etch lines into it with a laser.

...During the manufacturing process a laser scribes a series of ultra fine lines, allowing 10% of visible light to be transmitted through the panel...

Of course the efficiency goes down when you remove 10% of the photovoltaic material, but if you can put it up where windows used to be, you end up winning in the end. This is especially true for office towers and skyscrapers which mostly have exclusively glass exteriors. This technology will not replace existing panels. Current opaque solar technology will always have it's place on roofs and walls. The invention of clear solar panels allows those opaque panels to be complemented by making more surface area available to install panels on existing glazing surfaces.
• #### Could someone use multiple layers? (Score:3, Interesting)

on Monday August 09, 2004 @01:03PM (#9921320) Journal
To increase the amount of electricty generated, graned the inner layer would not generrate as much electricity, but could they manufacure a mutiple layer semi-transparent window pane? Maybe use the mutiple layers to increase effecincy per square ft.???

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