Transparent Solar Technology

See-through solar materials that can be applied to windows represent a massive source of untapped energy and could harvest as much power as bigger, bulkier rooftop solar units, scientists report today in Nature Energy.

Above – Highly transparent solar cells represent the wave of the future for new solar applications,” said Richard Lunt, the Johansen Crosby Endowed Associate Professor of Chemical Engineering and Materials Science at MSU. Photo by Kurt Stepnitz

Led by engineering researchers at Michigan State University, the authors argue that widespread use of such highly transparent solar applications, together with the rooftop units, could nearly meet U.S. electricity demand and drastically reduce the use of fossil fuels.

“Highly transparent solar cells represent the wave of the future for new solar applications,” said Richard Lunt, the Johansen Crosby Endowed Associate Professor of Chemical Engineering and Materials Science at MSU. “We analyzed their potential and show that by harvesting only invisible light, these devices can provide a similar electricity-generation potential as rooftop solar while providing additional functionality to enhance the efficiency of buildings, automobiles and mobile electronics.”

Lunt and colleagues at MSU pioneered the development of a transparent luminescent solar concentrator that when placed on a window creates solar energy without disrupting the view. The thin, plastic-like material can be used on buildings, car windows, cell phones or other devices with a clear surface.

The solar-harvesting system uses organic molecules developed by Lunt and his team to absorb invisible wavelengths of sunlight. The researchers can “tune” these materials to pick up just the ultraviolet and the near-infrared wavelengths that then convert this energy into electricity (watch a demonstration of the process here).

Moving global energy consumption away from fossil fuels will require such innovative and cost-effective renewable energy technologies. Only about 1.5 percent of electricity demand in the United States and globally is produced by solar power.

But in terms of overall electricity potential, the authors note that there is an estimated 5 billion to 7 billion square meters of glass surface in the United States. And with that much glass to cover, transparent solar technologies have the potential of supplying some 40 percent of energy demand in the U.S. – about the same potential as rooftop solar units. “The complimentary deployment of both technologies,” Lunt said, “could get us close to 100 percent of our demand if we also improve energy storage.”

Lunt said highly transparent solar applications are recording efficiencies above 5 percent, while traditional solar panels typically are about 15 percent to 18 percent efficient. Although transparent solar technologies will never be more efficient at converting solar energy to electricity than their opaque counterparts, they can get close and offer the potential to be applied to a lot more additional surface area, he said.

Right now, transparent solar technologies are only at about a third of their realistic overall potential, Lunt added.

“That is what we are working towards,” he said. “Traditional solar applications have been actively researched for over five decades, yet we have only been working on these highly transparent solar cells for about five years. Ultimately, this technology offers a promising route to inexpensive, widespread solar adoption on small and large surfaces that were previously inaccessible.”

Nature Energy – Emergence of highly transparent photovoltaics for distributed applications


Solar energy offers a viable solution to our growing energy need. While adoption of conventional photovoltaics on rooftops and in solar farms has grown rapidly in the last decade, there is still plenty of opportunity for expansion. See-through solar technologies with partial light transmission developed over the past 30 years have initiated methods of integration not possible with conventional modules. The large-scale deployment necessary to offset global energy consumption could be further accelerated by developing fully invisible solar cells that selectively absorb ultraviolet and near-infrared light, allowing many of the surfaces of our built environment to be turned into solar harvesting arrays without impacting the function or aesthetics. Here, we review recent advances in photovoltaics with varying degrees of visible light transparency. We discuss the figures of merit necessary to characterize transparent photovoltaics, and outline the requirements to enable their widespread adoption in buildings, windows, electronic device displays, and automobiles.

21 thoughts on “Transparent Solar Technology”

  1. Transparent solar cells are *transparent*; by definition they don’t gather most of the electricity. This is so stupid! I don’t understand what moron finances these type of research.
    What they should work on is lowering the cost of normal solar panels.

    • Visible light is just one part of the electromagnetic radiation spectrum we receive from the sun. Think for a second before you give your knee-jerk reaction.
      Regarding your final sentence, many, many companies are working on just that. But sometimes thinking outside of the box can lead to novel applications, like generating electricity from those glass-covered skyscrapers in this case.

      • @nerfer: “Visible light is just one part of the electromagnetic radiation spectrum…”

        Really? Wow, I didn’t know that. You’re so smart nerfer!
        Normal solar panels have efficiency of at least 15%. Transparent ones have up to 5%, which means that visible light that you so casually dismiss, has twice more energy than the transparent panels can harness.
        And why do you need to replace glass with solar panels?!
        Fist transparent solar panels will never be cheaper than glass. They’ll never be as efficient than normal solar panels (inherent value). They’ll never be cheaper than normal solar panels (and you need three times the area to harness the same energy). So again, why do you need them nerfer?!
        Wouldn’t it make more sense to put normal solar panels on the roof, you know, facing the actual power source instead another skyscraper?

        But I guess some charlatan in sillicon valley will find good use for them by selling these panels to wealthy grenwashers (using subsidies from the gov of course, because nothing says you’re “saving the world” more than taking money from the poor and giving it to the rich so that they can show how “green” they are).

        • On the other hand, the light that already hits those windows is 100% wasted. If it can be only 95% wasted, isn’t it an advantage?

          • “On the other hand, the light that already hits those windows is 100% wasted. If it can be only 95% wasted, isn’t it an advantage?”

            No Wtrmute, it’s not an advantage, because it will cost at least 20 times more than glass panels. There’s something called “opportunity cost”. Basically the money wasted on these panels could be put at better use somewhere else (like normal solar panels that deliver 3 times as much energy).

  2. If I had a $1 for every time I’ve read about some solar or battery breakthrough I’d be a very rich man. Just google “solar breakthrough” or “battery breakthrough” and you’ll get thousands of hits.

    Yet, here we are and I’m still waiting on painted solar, CPV and now see-through solar.

    • Rats
      If I had a $1 for every time I’ve read about some solar or battery breakthrough I’d be a very rich man. Just google “solar breakthrough” or “battery breakthrough” and you’ll get thousands of hits.
      Yet, here we are and I’m still waiting on painted solar, CPV and now see-through solar.

      Not to mention toxic free solar cells and manufacturing techniques. Oh wait! danielravenest claims no such things exist! My bad!

  3. “could nearly meet U.S. electricity demand”. Why is it they say this blanket statement instead of the more REALISTIC “daytime demand”?Do all these scientist and researchers think the lights will stay on when the sun goes down? Last I knew, or at least what I was taught in school, was that photovoltaic devices only produce power when light shine on them. Has that changed in the last 30 years?

    • He could be suggesting it could meet the total around-the-clock demand with energy storage.

      Now I don’t know if that’s true, but that might be what he is saying.

      • He explicitly mentions that improved storage is needed. He says this in the second half of the same sentence. It isn’t exactly hidden.
        I don’t see how he could be any clearer.

  4. Interesting idea, altho I don’t see it becoming real wide-spread. For one thing, a lot of those windows are north-facing. Windows stay in building for decades before being replaced, rooftop solar is cheaper to install and produces more energy for most cases.
    I can see it used in certain high-rise buildings, maybe back windows of cars, or in places where maybe you don’t want people to know you’re using solar.

    • Why? Wouldn’t ignoring the north facing windows be no different than ignoring and not utilizing north facing rooftops, as is done now? Applying this technology means a whole bunch of sun-soaked real estate (windows) can now be used as energy producing surface area when it previously went wasted and unused. That is a plus.

    • Photovoltaics work even if there is no direct sunlight.
      Whether they produce enough energy to make economic sense is of course another question.

  5. There’s a question so obvious that I feel silly rhetorically asking it. Well: “if transparent is such a game changer, then why not cover all existing ‘big, bulky, visible light PV’ with it?” You know, double the efficiency. Or triple. Heck, since there’s nary a word about what the output is, The Moon!

    There’s a secondary question that also is obvious. IF these things absorb IR (and UV?), what impact do they have on building heating? Remember most skyscraper windows are now triple ply with argon gas between the layers. The middle layer will usually have a strong IR reflector on one side. Just saying…

    There perhaps there’s two related points: if the energy collection (not efficiency) is so modest that no criss-cross electron pickup wires are needed, then tell me again why is this compelling? And the related question, is the stuff – like the highly touted commercial failure “Ovshinsky Amorphous Cells” supposed to be made of sufficiently cheap stuff, in a simple bulk process so darn cheap that it can be done profitably?

    Seriously. If the blokes talking up this stuff can come up with the middle glass/plastic film for the 3-layer skyscraper panes, come up with a solid manufacturing process to make the stuff in huge plates or rolls, develop the tech where it can literally be scored-and-snapped (if glass) or roll-sheared (if plastic), survive that indelicate procedure and be integrated into 3 ply panels, while retaining environmental integrity, full electron collection, robust weather insensitivity and a long service life … (and be cheap), then they might succeed.

    And their only customers will be Big SkyScrapers in Large American/European/Japanese cities. For now.

    I’d be happy with a specific output rating, and a potential specific energy future projection. Seriously.

    Remember this:
    The RED part is what gets down to Sea Level.

    Now, go wander over to this image:

    It is particularly telling in how responsive various materials are to the spectrum in general (without the sun’s on-dirt spectrum overlaid… I know, it makes it hard.)

    Point tho’ is, there isn’t all that much out there above around 800 nm. 30% of all sunlight. There’s also very few materials that’d be able to keep their response to the WIDE IR band, but leave out the visible. Organic dyes? How long are they going to last?

    Just saying.
    Show more info (especially in these articles; oft the stuff is paywalled. )


    • Just because transparent solar doesn’t severely impact availability of visible light to indoor occupants, doesn’t mean that it won’t lower the available solar energy for existing systems when placed in front of them. Besides, the purpose of this tech is to convert window surfaces to useful power-generating surfaces, not to retrofit onto existing solar power systems.

    • The answer to your first question is obvious – it is being done, they build multi-layer photo cells for efficiencies past 40%, see this for example:

      The answer to your second question is also obvious – if the IR is being reflected, then whatever IR makes it past the solar cells will be reflected back to it for another pass – a bonus! Heat from inside the building will stay inside the building, just as before. I don’t see a downside.

      Rather than baking it into the glass or plastic, I see it as a film that is applied once the window is made. That’s just a guess, but it seems reasonable to me.

      I already looked up the sunlight spectrum and saw that first graph. So yeah, if 30% of the energy is above the visible spectrum, that would explain the efficiency numbers as presented in the article. They’re not hiding anything.

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