Follow Slashdot stories on Twitter

 



Forgot your password?
typodupeerror
×
Technology Science

Clear Solar Panels Double As Projection Screens 304

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."
This discussion has been archived. No new comments can be posted.

Clear Solar Panels Double As Projection Screens

Comments Filter:
  • by DannyiMac ( 216056 ) on Saturday August 07, 2004 @09:10PM (#9911140) Homepage
    Wonder if they are more efficient than the solar panels mentioned in a previous /. story?
  • Cool! (Score:3, Insightful)

    by Zorilla ( 791636 ) 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...
  • Whats the point (Score:1, Insightful)

    by PROTEIN_MAN ( 803666 ) on Saturday August 07, 2004 @09:15PM (#9911158)
    Most glass is mounted vertically so it will only be good in the mornings/afternoons.....
  • by DaveInAustin ( 549058 ) 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:Cool! (Score:3, Insightful)

    by UberDork ( 235964 ) on Saturday August 07, 2004 @09:18PM (#9911172) Journal
    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?
  • by moonbender ( 547943 ) <moonbender@gmaEE ... inus threevowels> 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:Whats the point (Score:5, Insightful)

    by AlexMidn1ght ( 705563 ) on Saturday August 07, 2004 @09:29PM (#9911217)
    This is great since mornings and afternoons are the usual peak periods for electricity demand.
  • by irokitt ( 663593 ) <archimandrites-i ... m ['aho' in gap]> 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:Whats the point (Score:5, Insightful)

    by Captain Splendid ( 673276 ) <capsplendid.gmail@com> on Saturday August 07, 2004 @09:42PM (#9911261) Homepage Journal
    Most glass is mounted vertically so it will only be good in the mornings/afternoons.....

    Still much better than regular glass that doesn't produce any power.

  • by GileadGreene ( 539584 ) 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.
  • Um.... (Score:4, Insightful)

    by RobL3 ( 126711 ) 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......
  • by NanoGator ( 522640 ) on Saturday August 07, 2004 @10:01PM (#9911320) Homepage Journal
    "Is $19 million worth of glass really what you would want to get?"

    Depends, you have to ask more questions:

    1.) How much does the ordinary glass cost?

    2.) How much electricity is generated? How much would this reduce the yearly bill?

    3.) How much would/could electric prices rise?

    4.) How long do these panels last?

    5.) What other benefits are you buying? (I.e. is there resistance to power failures? Those in Cali during the rolling blackouts would appreciate that....)

    6.) How does this compare to the cost of the rest of the building?

    7.) Is running on solar power going to be attractive to tenants?
  • by silentbozo ( 542534 ) on Saturday August 07, 2004 @10:11PM (#9911351) Journal
    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.
  • Yeah Except (Score:5, Insightful)

    by deathcow ( 455995 ) on Saturday August 07, 2004 @10:14PM (#9911368)
    In many latitudes the Sun never comes anywhere close to being overhead. I've been in Alaska 28 yrs and never seen the Sun, Moon, or any planets even close to overhead. The highest they ever get is about 60 degrees above the horizon or so.
  • by putaro ( 235078 ) on Saturday August 07, 2004 @10:27PM (#9911412) Journal
    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)
  • by McCrapDeluxe ( 626840 ) on Saturday August 07, 2004 @10:32PM (#9911433) Journal
    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!
  • by theDunedan ( 462687 ) on Sunday August 08, 2004 @12:25AM (#9911826)
    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
  • The new math (Score:2, Insightful)

    by Anonymous Coward on Sunday August 08, 2004 @02:01AM (#9912057)
    I've seen strange math here today. Let's do the numbers.

    First, these cannot be used as windows on cars. The minimum tint is something like 20%, and these allow only 10% of the light.

    Second, at most two sides of a building receive sunlight at a time. In fact, it's the average of the cosine of the angle of incidence that matters.

    Third, less energy gets through the atmosphere when the sun is near the horizon -- much less.

    What we really want is the average of the product of the cosine with the transparency of of the atmosphere, which is equivalent to around 3 hours of straight on sunlight per day per 3 panels (none on the north face).

    At 3.8 watts/sq-ft, it's about 3.8 watt-hours per day, per sq ft.

    Electricity costs $0.08 per kilowatt-hour, so 1 sq ft of panel produces about 0.3 milli-dollars of electricy per day.

    Because of clouds, there are around 150 clear-sky equivalent days/year, so that's about 5 cents per year.

    Assuming a measly 3.3% interest rate, that income stream is worth $1.50 if that sq. ft. of panel lasts forever, or about 75 cents if it lasts an average of 20 years.

    And the panel costs $45 per sq ft.

    This is offset by the cost of glass which it replaces, which is neglible.

    Most of the costs of production are energy, in one way or another (which is the point that most environmentalist REFUSE to admit). Even including a carbon-dioxide tax, these have to be much cheaper before they can be considered environmentally-friendly.
  • Economics (Score:1, Insightful)

    by Anonymous Coward on Sunday August 08, 2004 @04:00AM (#9912272)
    The key factor in the economics of solar energy is interest rates. If interest rates are low enough, then they become cost-competitive with other forms of power.

    ----------
    Gay mobile porn [studmobile.com]

  • 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...

  • Re:Cool! (Score:3, Insightful)

    by John Hurliman ( 152784 ) on Sunday August 08, 2004 @05:36AM (#9912431) Homepage
    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 efficient model, invest that at a given rate, and calculate the compound interest each year until the year that the efficient model would supposedly "pay itself off". Then take the cost savings each investment period from the more efficient model, and invest that in to a growing account at the same rate and figure out the compound interest on that for the same period. Graph it out in Excel and you might be surprised at the results, and think twice when someone tries to sell you something that will "pay itself off in x years".
  • Re:The new math (Score:3, Insightful)

    by Donny Smith ( 567043 ) on Sunday August 08, 2004 @06:24AM (#9912537)
    >First, these cannot be used as windows on cars. The minimum tint is something like 20%, and these allow only 10% of the light.

    Riiiight. You can put them on the roof and probably rear side windoews.

    >Third, less energy gets through the atmosphere when the sun is near the horizon -- much less.

    For the roof top panel noon is the best.
  • Re:Ah, I see (Score:3, Insightful)

    by horza ( 87255 ) on Sunday August 08, 2004 @07:57AM (#9912681) Homepage
    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 VOS Pad [findaproperty.com] is lit only by ultra-bright LEDs, around 400 LEDs grouped into 135 fittings that can show 16.7M colours, and only consumes 360W when every light is fully on. Computers are way over-powered for 90% of users and people could benefit by buying a less power-hungry machine (even a laptop, as their prices have dropped drastically).

    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.)

    New OLED technology should cut the power even of the LED display considerably as it no longer needs a back-light.

    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?

    Wrong answer. The best thing is to attack it from both ends, the suppy and the demand. I don't understand some of the "it won't supply 100% of my needs" negativity by some people (not yourself). If someone came and showed me how I could lower my electricity bills by eg 50% then I'd be interested.

    Phillip.
  • Money (Score:3, Insightful)

    by ttfkam ( 37064 ) on Sunday August 08, 2004 @01:57PM (#9914223) Homepage Journal
    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 is not practical. The return on investment would likely take the better part of your life -- if even that short. Sure, it could take this portion of your energy consumption off the grid, but how much energy was required to make these materials in the first place? How much energy was used by the manufacturing facilities? At a price of £35,000, you can bet it isn't peanuts.

    As for OLEDs, yes they look promising. However, until they actually hit mass market, we don't know actual numbers. Looking at this press release [zdnet.co.uk], Samsung's 17" display "will consume no more power than a 15-inch display..." Sure you can take away the backlight, but this is not the same as slashing the total power consumption. Reduces it, yes, but doesn't make revolutionary drops. On the bright side (no pun intended), OLEDs have the potential for cost savings.
    The best thing is to attack it from both ends, the suppy and the demand. I don't understand some of the "it won't supply 100% of my needs" negativity by some people (not yourself). If someone came and showed me how I could lower my electricity bills by eg 50% then I'd be interested.
    You're right. We should attack it from both ends or at least leave everything open as possibilities. However I still believe that I was right. We should not concentrate on technologies that only provide marginal improvements for the amount of money/resources spent. We shouldn't ignore them of course, but we definitely shouldn't fixate upon them. We have a limited amount of resources and money. For better or for worse, this is the reality of our world: scarcity and commerce.

    Who cares if my electricity bill is reduced by half or even eliminated entirely if the initial cost in materials exceeds what I would pay in electricity for the next fifty years?

    If a solution presents itself that uses more resources or costs substantially more than our current methods, it is not a good solution. In some circumstances I could see this PV glass making sense. In most scenarios though, I see it as a curious novelty that makes little sense for the average Joe like myself.

    As I look out one of the windows in my bedroom, I estimate that the 2.5 by 3 foot window would cost me around $337.50 to replace just the glass. (I'm sure the framing would add to the cost.) I have three such windows in my bedroom. For some odd reason, I think my money would be better spent on double-paned replacements and using the money saved on both initial investment and heating costs to pay for my energy bills until the technology improves in a few years.

    At $45/sq. ft., the $1,012.50 (at least) I would spend on three PV glass windows would not be recouped anytime soon. I like to think of myself as an optimist, but I'm not that blindly optimistic. Assuming 22.5 sq. ft. of PV glass, 3.8W/sq. ft., 7hrs of useable sunlight a day for 22 sunlit days a month (on average), I get a little more than 13kWh (kilowatt hours) per month. Let's say I pay about 10 cents per kilowatt hour -- pretty expensive I think. This means I get back $1.32 every month from these windows. Woohoo! I will have paid for them in 64 years! Well... That's assuming they last for 64 years.
  • by Lihtan ( 803863 ) 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.

The solution of this problem is trivial and is left as an exercise for the reader.

Working...