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Power Windows

Solar Windows Could Help Power Buildings 89

Posted by Soulskill from the people-in-solar-houses-shouldn't-throw-stones dept.
Lucas123 writes: Several companies are now beginning to roll out translucent photovoltaic films or solar cells embedded in windows that can supplement a significant amount of energy in the buildings where they're used. SolarWindow Technologies, for example, is preparing to launch a transparent product made with organic PVs, while another company, Solaria, is cutting solar cells into thin strips and embedding them in windows. Both companies admit their products can't produce the 20% efficiency ratings of today's best rooftop solar panels, but they say that's not their objective. Instead, the companies are looking to take advantage of millions of skyscraper windows that today are simply unused real estate for renewable energy. One company is aiming at supplementing 20% to 30% of a skyscrapers power requirements. Meanwhile, universities are also jumping into the solar window arena. Oxford University has spun off a PV window company that produces semi-transparent solar cells made of semi-transparent perovskite oxide that has achieved a 20% solar energy efficiency.
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Solar Windows Could Help Power Buildings More

Solar Windows Could Help Power Buildings

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  • Are they already designed using multiple layers? I'm no photovoltaics expert, but with 20% efficiency per layer couldn't they combine 5 layers to achieve "100% efficiency" per window? Seems like with enough windows a building could theoretically get all of its power from solar - at least on sunny days.

    • Re:Multiple layers? (Score:5, Funny)

      by preaction ( 1526109 ) on Friday September 04, 2015 @01:18PM (#50458713)

      You're also no mathematician

    • Re: (Score:1)

      by Anonymous Coward

      Why not add a sixth for 120% efficiency /s

      • Why not add a sixth for 120% efficiency /s

        Actually you can do that with just 5. You need to flip the two inside layers around and they can convert the light from the florescent ceiling lights.

    • Re: (Score:2)

      by asn ( 4418 )

      Wait now... this dude is on to something. What would happen if they combined SIX layers?!

      *mind BLOWN*

    • Remember that light energy can't be converted to electricity and also transmitted through the window; whatever percentage gets converted to electricity must be subtracted from the percentage that is transmitted. A window that converts 100% of solar energy to electricity would transmit 0% of the light; i.e. it would be opaque.

      • > Remember that light energy can't be converted to electricity and also
        > transmitted through the window; whatever percentage gets converted
        > to electricity must be subtracted from the percentage that is transmitted.

        A hot summer day...
        * incoming sunlight reduced; check
        * some electrical power provided for air conditioning; check

        Now that's what I call win-win.

    • Re: (Score:1)

      by Anonymous Coward

      "100% efficiency" per window?

      Yes, but then we don't call them windows any more.

      • Yes, but then we don't call them windows any more.

        Yeah, but they would be great to *really* cool the room down.

      • "100% efficiency" per window?

        Yes, but then we don't call them windows any more.

        And that's why basement-dwelling übergeeks use Linux.

  • This is kind of a trope (Score:4, Interesting)

    by Anonymous Coward on Friday September 04, 2015 @01:29PM (#50458791)

    Cities don't have anywhere near the solar density necessary to make a dent in their consumption. There's just barely enough in a neighborhood, but when you get to multi-story density, it's a hopeless gesture.

    It gets even worse when you use thin-films which have waaaay less efficiency than crystalline panels.

    And it gets even worse when you mount them on vertical surfaces like skyscraper windows.

    And it gets even worse when you have thousands of distributed pieces of small electronics that all must be maintained, managed and the energy combined.

    I loooove solar and I can tell you it's just NOT WORTH IT. Make a big field outside the city and send the power in. Everything is a waste of time or just for show.

    A lot of people have emotional feelings like, "but it's all just going to waste in the city." But use your head: It's all just going to waste out in the desert too. So be wise and put efficient, dense PV where there's lots of sun. Don't put inefficient PV distributed around where there's weak sun.

    It's like trying to write a letter with twenty light pencils. Just use one dark pencil.

    • If they put the panels out in the fields, make sure they're built high enough to put shelters, roads, etc underneath. I see them on the ground, and that is truly wasteful. The land can't be used for anything else.

      • Around here they put solar panels in the empty space in freeway interchanges, land that can't be used for anything else.

    • Re: (Score:2)

      by mlts ( 1038732 )

      It is about killing multiple birds with one stone. Windows need film on them anyway for color, so might as well plaster the south side with a film that generates a few kilowatts of electricity. This also gives some positive PR, even if the only thing the electricity did was feed a rack of UPS batteries so less mains power was needed.

      You are correct... it won't get near as much electricity as a panel mounted horizontally, and each square inch gets far less energy than a PV panel... but it does something, d

      • Windows need film on them anyway for color, so might as well plaster the south side with a film that generates a few kilowatts of electricity.

        Sure, it's no problem if the installation and maintenance of the stuff result in a net energy loss.
        We'll make it up in volume!

      • Re: (Score:2)

        by jblues ( 1703158 )
        If you want to kill birds wind power is a much better option.

      • An ideal solution would cause the windows to tint themselves as the light becomes more intense, perhaps by making tiny little mirrors that twist when (solar) heated to focus more of the light on the PV elements. Double-win: extra shade when you need it most plus harvest the energy as electricity instead of having it convert to heat.

    • Now stop with this negativeness. Remember, electrons flow from negative to POSITIVE.

    • You are just an idiot who never dug into the topic and now risks a big mouth.

      Basically eery surface in a city can be covered with nearly zero cost film solar "material".

      For windows ofc you want something that lets 90% or more or less light pass through, otherwise you spoil the idea of the "window".

      Paint/thin film solar pv stuff is a huge contributor to the solution.

      I suggest you read a bit about those technologies.

      • There's an argument that thinfilm window coatings tuned for Infrared and Ultraviolet might be useful.

        The counterargument is a straight economic analysis of whether the cost of installation will be outweighed by the energy savings/generation.

        My money is that the numbers say "don't bother"

    • So you want to say that it's useless to put those thin film miracles in my office windows (20 sq meters or more) and just put a pathetic solar film wich produces nothing? if this 20sq meters area can give me ~1kw(they can do more ofcourse) energy why not? Also did you considered that these films can also be used in the walls? Just think of it.

    • Re: (Score:1)

      by catprog ( 849688 )

      New York State:

      11,131GWh / month http://www.eia.gov/state/?sid=... [eia.gov]

      8,525GWh/ month non Renewables

      82 GW of solar required for 3.5 hours /day 30 days.

      At 10% efficiency = 820 km^2
      At 20% efficiency = 410 km^2
      Area of New York = 1,214 km^2(Although 789 km^2 is land)
      Metro Area of New York = 34,490 km^2

  • For HVAC, makes sense, but may lose on aesthetics (Score:4, Insightful)

    by Koreantoast ( 527520 ) on Friday September 04, 2015 @01:43PM (#50458867)
    As the article noted, the double benefit of this system is not just the token energy it generates but the ability to better control HVAC costs by reducing the amount of heat that goes in through the windows, reducing demands on air conditioning in the summer. That being said, based on the pictures, this system is not pretty: the lines running through the translucent cells are rather annoying to look at and could be shot down by builders for the aesthetics alone. It would be better if they could deploy this as some sort of window shade that can be retracted to allow for unobstructed views (looking at the photos of the sample setup, it reminds me of the translucent shades used in a lot of newer offices), but I don't think this technology is there.

    • Re: (Score:2)

      by TWX ( 665546 )
      Or we could stop designing our buildings to look like they're made out of glass...

      • Not everyone likes living in a basement...

      • Maybe we could remove all skeumorphism, transparency, bevels, borders, and gradients here in the real world as well? I propose we call this style "new metro!"

    • Allowing less heat in would be good for the summer but bad for the winter. For that, I think the windows lined with e-ink would help. The windows can be set to darken during the day in the summer and clear during the day for the winter. In the winter, when you want privacy, there's a capability to scatter the light coming through to blur the view without blocking a significant amount of the light from getting in. These windows would look nice and they could eliminate the need for blinds or curtains. Se

    • Re: (Score:3)

      by jbengt ( 874751 )

      . . . benefit of this system is not just the token energy it generates but the ability to better control HVAC costs by reducing the amount of heat that goes in through the windows, reducing demands on air conditioning in the summer.

      As if they don't already routinely apply much cheaper coatings specifically designed to do that.

    • Far more helpful would be to add awnings over windows like the Petronas towers have. The view is not obstructed, but high angle sun is largely never hitting the windows.

  • Forgetting something (Score:5, Insightful)

    by CanadianMacFan ( 1900244 ) on Friday September 04, 2015 @02:22PM (#50459027)

    The article talks about changing all the south facing windows in the office towers. It sounds great but in the city there's usually another tall building across the street blocking the sun so there's not much point in changing all of the windows. Maybe the ones near the top that does get the sun. I could see it being of more use in less dense areas but not in city centers.

    • Yep. It would be better for all involved to make a high efficiency building (often with smaller and fewer windows), and then pay for a remote solar farm. Moving power around is relatively efficient, especially compared to the losses from city shadows and design trade offs.

      Solar windows for self sufficiency makes about as much sense as trying to put in hydroelectric power systems on the sewer lines leaving the buildings. Technically there is power to be had, but you efforts and money are almost certainly

    • As someone who works in the design industry doing daylighting studies, this isn't hard to account for... But even without that, if you're a smaller building being dwarfed by a larger one, you're probably not large enough to use this strategy. if you're a big enough building, then you might be bigger than those around you. problem solved without any math being done.

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