The Window to the Sol

Your windows could collect solar energy, says study 7

Have windows? Then you could collect solar energy, says a new study published in the journal Science. Researchers at the Massachusetts Institute of Technology have developed a light-absorbing dye that, when painted on a window, transfers energy via the glass into solar cells at the window's edges (through a process we don't pretend to understand). If the dye-coated glass is placed atop a solar panel, wavelengths of light that sneak through the glass can be converted into electricity by the panel. "We saw approximately 30 percent higher performance in the combined system compared to a stand-alone solar cell," says coauthor Marc Baldo. "We think that ultimately this approach will allow us to nearly double the performance of existing solar cells for minimal added cost." The MIT folk say their "solar concentrator" is inexpensive, easy to manufacture, and could be marketed within three years.

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  1. vakibs's avatar

    vakibs Posted 10:06 pm
    10 Jul 2008

    good news for solarThis is great news.. Solar PV panels of future would achieve close to 50% efficiency in converting solar energy to electricity.
    I hope the production costs scale up well.

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  2. vakibs's avatar

    vakibs Posted 10:21 pm
    10 Jul 2008

    some numbersDirect solar energy of mid-day sun : 1000 W/m^2
    Average solar energy hitting the roofs : 1/4 (daylight factor) * 1/3 (sunniness) * 1000 = 80 W/m^2
    Average solar energy in deserts would be much higher .. around 300 W/m^2
    Current solar PV has an efficiency of 20% in converting the sunlight to electricity = 16 W/m^2
    Physics laws limit the maximum extent of solar energy to be converted to electricity at 60%. This is the bound.
    Coating with these color dyes will double the efficiency.. so we might obtain efficiencies around 40% for solar PV = 32 W/m^2
    There is talk of a new generation of panels with 30% efficiency. Coated with these dyes, they might get close to 50% efficiency = 40 W/m^2
    Mass producing these panels will be a good day for mankind.

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  3. Caroline Posted 1:45 am
    11 Jul 2008

    One (small) drawbackIf these coatings are light-absorbing, doesn't that mean that less light actually enters the building? I can see that being a drawback in current residential buildings, especially in high latitudes. As someone who values my natural daylight, I think I'd begrudge losing any more sunlight and having to supplement with artificial.
    Which doesn't mean that it's a bad idea all-round, of course.  

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  4. archigeek Posted 1:56 am
    11 Jul 2008

    Wow...That's a pretty impressive innovation. Could make solar PV more competetive relative to other generation types. That's rather exciting. Now if they could just bring down the prohibitive cost of PV in the first place.

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  5. katmainomad Posted 5:39 am
    11 Jul 2008

    drawback or bonus - depending on where you liveOf course this would actually be an advantage in hot, sunny places like the American Southwest - windows that let in less light to heat up your already hot room, AND solar electricity as a bonus.  Too bad I don't live in on of those places :)  

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  6. lbibayoff Posted 6:52 pm
    11 Jul 2008

    Re: One (small) drawbackIf you click on the link to The Guardian source, it states that the coatings absorb light outside the visible spectrum (assuming infrared and/or ultraviolet).  This can be beneficial in that the absorption of infrared perhaps leads to a cooler window that allows less heat to penetrate into the building.  Furthermore, the absorption of ultraviolet rays means skin and eye protection and prevents the fading of interior colors.

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  7. Caroline Posted 12:14 am
    12 Jul 2008

    more on that small drawback....Well, I love reading the Guardian because it's always so optimistic about these things! However, the New Scientist article is a bit more balanced, and it does look like there are some drawbacks. The coatings presently last only three months, for example.
    The overall impression I've got it that this might be a good thing for solar cells, but  perhaps not so viable for retrofitting a domestic house. And anyone who relies at least partly on passive solar to heat their house in winter will probably have to re-think. Still, it's swings and roundabouts, like most technologies, and for some areas of the world like Sub-Saharan Africa this could be a godsend.  

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