Clean Power

Published on February 7th, 2013 | by Nicholas Brown


Nanoantenna Solar Cell Efficiency Can Blow Silicon Out Of The Water

February 7th, 2013 by  

Today, conventional silicon solar cells are 10% to 20% efficient (this means that they generate 100 watts to 200 watts per square metre of cells, respectively). These conventional panels are already in use worldwide, and they do work well; however, more efficient panels would still be very helpful in multiple ways.

Brian Willis in bimolecular and chemical engineering stands in front of an X-ray photoelectron spectrometer
Image Source: Sean Flynn/UConn

There is a theoretical technology that involves using a nano-sized rectenna — or a rectifying antenna — which, as the name implies, can absorb and rectify solar energy into direct current (DC).

It can achieve a theoretical maximum of 70% efficiency, which is stunning by any standard — only hydroelectric power plants can surpass this level of efficiency. The efficiency of almost all the other power plants is below 50%.

Unfortunately, this concept has been limited because scientists do not know how to construct and test it. Researchers at the University of Connecticut may have the answer to this puzzle, however. It is called selective area atomic layer deposition (ALD).

According to, ALD is what it would take to finally manufacture a working prototype of this recent type of solar cell.

“In a rectenna device, one of the two interior electrodes must have a sharp tip, similar to the point of a triangle. The secret is getting the tip of that electrode within one or two nanometers of the opposite electrode, something similar to holding the point of a needle to the plane of a wall.”

The integration of solar panels into devices is far cheaper than paying contractors to construct mounting equipment and put the panels on the roof, and integrated panels that are 70% efficient can power laptops and cellphones on a smaller scale as well. A 60-watt panel of this type could be mounted on a 17-inch notebook computer, for example. 

More efficient solar panels would also use less space, and hence could be stored, shipped, and installed at a lower cost than conventional ones.

As noted above, these aren’t the first researchers to work on this type of solar technology. We reported 2.5 years ago on solar antenna technology MIT scientists were working on that could supposedly “concentrate solar energy 100 times more than a regular photovoltaic cell.” The clincher, of course, was getting the costs down. Those carbon nanotube solar antennas don’t seem to have made it to market yet. Will these rectifying antennas?

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About the Author

writes on CleanTechnica, Gas2, Kleef&Co, and Green Building Elements. He has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is:

  • jburt56

    This could be the Big Kahuna for solar.

  • Henry Stidston

    Would eSolar’s CSP be an example of cheaper CSP?
    See eSolar’s founder Bill Gross on YouTube show how he’s cut the costs.

  • Zer0Sum

    Concentrated Solar Power can already get over 97% efficiency. The only reason it is not more widely adopted is because it is a direct threat to the established energy players.

    • CSP is too expensive. I recently saw a top dog at one of the top CSP companies basically say that. And while I can’t repeat it, I heard the price per kWh of the largest single-unit CSP plant in the world, about to be online, and it’s WAY above the price of PV. the manager of the power plant and the plant’s process engineer both separately predicted (in interviews with me) that most of Abu Dhabi’s solar power would come from PV.
      CSP has some benefits, and it will survive in niche markets — it can complement PV. however, without some serious technological breakthroughs, it can’t outcompete PV for most needs.

      • Zer0Sum

        I appreciate that you have been to Dubai to see what they are up to but did it ever occur to you that they have a vested interest in artificially inflating the price of CSP and the global market in general?

        After all it’s just a few pipes, sheets of metal and a standard steam turbine power station which can be bought off the shelf from Seimens.

        CSP can be a lot cheaper than it is currently simply by taking out the excessively inflated construction costs and copious amounts of graft. Let alone the efficiencies that can be gained by economies of scale and advances in technology.

        Apart from that I’m really surprised that you have reprinted information from and MIT to boot. You should know better by now. is a straight up misinformation project run by the US Military and MIT haven’t done anything worthwhile, like pretty much ever.

        • Bob_Wallace

          A vested interest in artificially inflating the price?

          Companies around the world who are building CSP are artificially inflating the price of the electricity they produce?

          Companies around the world are deliberating pricing their product to fail?

          Physorg ” is a straight up misinformation project run by the US Military and MIT haven’t done anything worthwhile”?

          Do you realize how tinfoil-hattery that sounds?

          • Zer0Sum

            Re: Prove me wrong then Bob.

            There is definitely a serious problem with the inflated price of CSP systems. There is absolutely no logical reason for it to cost more than PV. We produce hundreds of miles of high quality and cheap steel on a daily basis.

            We have well proven and highly efficient technology for gigawatt sized power stations.

            The main thing propping up the PV market at the moment is the fact that the Chinese Government has heavily subsidised it’s manufacturing industry in order to flood the global market and beat the Americans at their own game of monopoly.

            Take away all the subsidies around PV and get rid of the cronyism and graft of all the other major energy industries and CSP is the only thing that stands on it’s feet, is quick and easy to manufacture and install, and has the capacity to actually be able to solve the global energy crisis.

            However that sounds too much like commonsense for the global Irrational Elite to allow it to actually happen. How would they justify all their wars if we didn’t have any energy issues any more and every major city in the world was energy independant?

          • Bob_Wallace

            Zero – you’re wandering into coo-coo land.

            You claim that a web site that was founded by a bunch of Brits and run from the Isle of Man is a CIA front and you want me to prove you wrong.

            And you post a link to a page that says nothing.

            Drag yourself back to reality or please go away. This site is crackpot intolerant.

          • Zer0Sum

            It’s a standard method by people like yourself to label as a crackpot anyone who is not keeping quiet about the BS lies that are being spread by sites like physorg.

            You can keep living in denial Bob. Physorg is definitely a misinformation website. Every single article on that site is full of overt errors even on basic math and they refuse to have any kind of serious discussion about their crap reporting. Even going to far as to silence anyone who questions their motives.

            BTW, why do you choose to defend physorg instead of discussing the clearly ridiculous claim that PV can only manage 10 – 20% when even this site has regular articles about the latest advances in PV being able to go as high as 48%?

            One thing I like about Clean Technica is that you generally attempt to publish a less biased presentation of information. But if you guys are going to insist on republishing total crap from sites like phsyorg then you are no better than them.

            I understand that you have an agenda but going as low as physorg is scraping the bottom of the barrel.

          • Bob_Wallace

            “Physorg is definitely a misinformation website.”

            ” Every single article on that site is full of overt errors even on basic math and they refuse to have any kind of serious discussion about their crap reporting. Even going to far as to silence anyone who questions their motives.”

            Physorg sources their articles at the end of each article.

            Physorg has a comment section following each of their articles. I post and discuss there from time to time.

            You need to prove your charge or go away.”

          • Zer0Sum

            I gave up on physorg three years ago. Their articles are just frustrating. I’m surprised that you consider them to be capable reporters let alone that you have missed all the errors they constantly make.

          • Bob_Wallace

            In other words, you ain’t got jack….

          • Zer0Sum

            No Bob, As I already explained they make so many errors in their scientific reporting that either they are completely stupid or doing it on purpose. I’m pretty sure they are not completely stupid otherwise they wouldn’t be able to build the website in the first place. Hence the only conclusion is they are a misinformation website. Due to the bias that they display and previous conversations with their editorial crew I have seen their true colors years ago.

            It’s your choice to fill your head with their propaganda. Don’t get upset at me if I don’t want to do the same.

          • I’d contend that it’s much more likely that it’s accidental.

          • Bob_Wallace

            Zero. If you would like to participate in discussions on this site you need to refrain from conspiracy theories and unsubstantiated claims.

            Having interacted with you a bit I expect I understand how the conversations with the PhysOrg editors played out.

          • Zer0Sum

            It’s not a theory or unsubstantiated. They have run a misinformation campaign for the past several years. After hundreds of published articles it is not accidental that they constantly misrepresent scientific facts and mislead the reader. As well as their very obvious editorial and content bias towards the established players particularly in the military, oil and nuclear industry.

            You don’t know how the conversation went and using this discussion as a reference leaves you severely misrepresenting the ability of the physorg editorial crew to argue their case. In fact their only method was to censor any discussion that did not fit with their slanted bias.

        • I wasn’t in Dubai. Just Abu Dhabi.

          The first company I was mentioning was not from the Middle East. I’d have to check again, but think it was a French company.

          The main engineer I talked to at Masdar is not a sell-out — he’s a sincere solar enthusiast and actually is focusing on CSP for his PhD and seemed much more into it than PV. And, quite frankly, if there was a way to get CSP competitive, someone would do it — don’t of money in that arena.

          Physorg mostly just reprints press releases from universities and research institutes.

        • nucheB

          Not correct. CSP needs tracking technology and systems. Just the cost of this tracking system and technology costs are comparable to total PV costs, leave alone steam boiler-turbine -generator etc. Steam turbine off the shelf from seimens is not free, you pay lot of money for that. Only reason PV can not compete currently against fossil and nuclear right now is because we don’t have cheap electrical storage/batteries, otherwise it is game over my friend. I actually work in CSP industry and academic research.

    • Does the 97% efficient CSP system use waste heat from the solar panels to heat water? If so, it can be terribly efficient.

      • Quotheraving

        Firstly CSP (Concentrated Solar Power) doesn’t employ PV solar panels, you are thinking of CPV (Concentrated Photo Voltaics), CSP uses the heat of the concentrated solar energy to directly or indirectly generate electricity.

        Secondly CSP isn’t 97% efficient as today’s most efficient CSP systems (sun tracking dish concentrators) only achieve a maximum efficiency of around 35% and typically operate well below this in practise, with an operating efficiency of 20% being commonplace.

        However this efficiency comes at a high price and CSP systems are expensive both to construct and maintain, and as a result compete poorly with fossil fuels at todays prices. This is one of the reasons why nantennas or solar rectennas are so interesting as they not only offer high potential conversion efficiencies, but more importantly are potentially very, very cheap.

        Finally the claim of a 97% efficiency isn’t just wrong – it’s physically impossible!

        The laws of thermodynamics place a maximum limit on the efficiency of any solar power generation of around 86%.
        However the design of the solar collector will reduce this, for instance the most efficient form of collector, a sun tracking dish concentrator operating at 800 – 8000 suns concentration could only achieve an absolute maximum efficiency of around 80% – and as I mentioned previously these systems operate in real world conditions at around 35% efficiency max.

        In short Zer0sum is full of it.

  • nrmantena

    Please give details of the Research groups at University of Connecticut, MIT
    and other research teams in the US, Europe and Asia. This technology seems to be right at the cutting edge of what all nations should be doing.

    • Links to the sources are in the posts. Let me know if you don’t find them.

  • JMin2020

    This was money well spent. At last. A real possibility for a full spectrum PV Module. I look forward to more progress on this piece of hardware.

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