Clean Power MIT solar cell efficiency

Published on May 31st, 2016 | by Tina Casey

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New Solar Cell Breaks Efficiency Ceiling, Theory Goes Out Window

May 31st, 2016 by  

If you thought the upper limit of solar cell efficiency was 32 percent in April, think again in May. Last week, MIT News reported on a research team that demonstrated how a silicon solar cell could top the theoretical limit of 32 percent. See you later, Shockley-Queisser Limit, and don’t let the door hit you on the way out.

To be clear, William Shockley and Hans J. Queisser can rest easy. The demonstration involved a silicon solar cell modded out with some other special material, so although MIT is pitching this as a theory-breaker, some people might prefer to mark it with an asterisk. Still, it’s a highly significant finding that could provide the silicon solar cell market with new life even as perovskites and other new solar cell variations emerge on the horizon.

MIT solar cell efficiency

Solar Cell Efficiency Gets The Heat Treatment

The key to the new solar cell efficiency breakthrough is something called thermophotovoltaics, in which carefully tailored materials are deployed to trap heat from the sun before it can reach the solar cell itself.

The extra materials then emit the heat in the form of thermal radiation, which is tuned to wavelengths that can be assimilated by the solar cell.

That’s the short version. If you’re looking for the full rundown you can find it in the journal Nature Energy under the title, “Enhanced photovoltaic energy conversion using thermally based spectral shaping.” Here’s a taste:

Here, we demonstrate enhanced device performance through the suppression of 80% of unconvertible photons by pairing a one-dimensional photonic crystal selective emitter with a tandem plasma–interference optical filter.

I know, right?

So Much For Solar Power Being Unreliable

Clean power foes are still clinging to the idea that solar energy is unreliable, a position that is becoming more and more ridiculous given the rapid progress in energy storage, smart grid technology, and related factors like advanced weather modeling.

The new solar cell breakthrough makes the naysayers look even more ridiculous, by opening up the potential for high efficiency solar conversion even on cloudy days. The extra material — a combination of nanophotonic crystals and vertically aligned carbon nanotubes, to be precise — acts as a mini onboard solar thermal storage unit, smoothing out dips and spikes as clouds pass across the sun.

The thermal element also provides a convenient bridge for pairing the new solar cell with standalone thermal energy storage systems.

The team worked with carbon nanotubes because they are “virtually a perfect absorber” of the color spectrum, enabling the new solar cell to capture all of the solar energy that hits it in the form of heat. As the heat is re-emitted in the form of light, the crystals convert it to colors that enable the photovoltaic material to close in on its peak efficiency.

Breaking the theoretical maximum is quite complicated, as the system requires a concentrating solar system to maintain high heat, and an optical filter to sort the desired wavelengths out from the undesirable ones.

That leads to the question of whether the cost is worth the effort, but the researchers anticipate that the system could be deployed to reduce lifecycle costs of concentrating solar systems, by managing heat generation and reducing the risk of damage.

What Now, Peter Thiel And Donald Trump?

Don’t hold your breath for that new solar cell to hit the market. The new research is a step or two above the proof-of-concept stage, and it describes an early-stage demonstration (see photo at the top of this article) using a low efficiency photovoltaic cell.

The result was an overall efficiency of 6.8 percent, which hardly sounds earth shattering (let alone ceiling-breaking), but the key point is that the figure of 6.8 was a real-life match for the team’s prediction.

Here’s researcher David Bierman describing the significance, as cited by MIT News

“…This is the first time we’ve actually put something between the sun and the PV cell to prove the efficiency” of the thermal system. Even with this relatively simple early-stage demonstration, Bierman says, “we showed that just with our own unoptimized geometry, we in fact could break the Shockley-Queisser limit.

As for what this all has to do with Peter Thiel, the tech tycoon has been all over the news this week for his secretive funding of the Hulk Hogan “sex tape” lawsuit against Gawker Media. Thiel is also well known for encouraging other tech tycoons to invest in software rather than putting up Benjamins for clean tech R&D efforts like this one.

We bring this up because Thiel is an active supporter of presumptive Republican nominee Donald Trump in his quest to become President of the United States. One could assume that if Trump wins the office, Thiel would be in a position to amplify his message to investors and public policy makers.

On the other side, presumptive Democratic nominee Hillary Clinton has carved out a slot for increasing public dollars for solar innovation in her ambitious slate of clean power proposals.

Just saying.

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Photo: via MIT News, courtesy of the researchers.


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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.



  • Kefdog

    WTF?
    Did a perfectly thoughtful article just segway into a Trump thread?
    We are doomed.

  • The political situation is more complicated then described here. Yes, Trump thinks that global warming is a hoax and wants to rip up the climate accord. Thiel is a libertarian which seems like an odd match for a protofascist like Trump. However, Thiel has also invested money in Elon Musk’s ventures, so he is not necessarily against renewable energy.

    At this point the real choice is between Bernie Sanders and Hillary Clinton. Sanders has the best record in congress on climate change according to the Climate Hawks. He wants to implement a carbon-fee-and-dividend which puts a rising price on carbon but returns 60% of the tax to legal residents in a monthly check. The other 40% he wants to dedicate to clean energy projects and climate adaption projects which are targeted to the poorest and most vulnerable.
    Sanders also wants to ban all extraction of hydrocarbons on federal lands, coasts and Arctic waters and he promises to enforce the Clean Water and Clean Air Acts to stop a lot of fracking and mountain top removal projects. Sanders says that climate change is a crisis in every speech and we need to act as soon as possible.

    Clinton promises to massively promote solar, but she doesn’t say how much money will be expended to do it. In fact, she basically promises that solar will continue growing at the current rate, which is important, but is hardly an ambitious goal. She appears to believe in Obama’s “all of the above” energy policy because she has taken large amounts of money from the fossil fuels industry. As secretary of state she promoted fracking around the world and her husband took large speaking fees from two of the banks which were promoting the XL Keystone pipeline, which may explain why her state department issued reports favorable to the pipeline. Under pressure from environmentalist groups, Clinton pronounced in 2015, that she was against the pipeline, right before Obama officially rejected it, but it appears that the real reason was that the lower price of oil had made the tar sands uneconomical, so Transcanada was abandoning its application. Unlike Sanders, Clinton believes that fracking can be done in a way which is safe for humans and without contaminating the ground water.

  • The Shambolic Skeptic

    Solar isn’t ‘unreliable ‘ it is intermittent. And so yes there are methods of storing energy off hours and off season, but the cost of such systems should be included when comparing PV solar to other energy producing systems.

    Often times storage costs are not included and neither are the grid cost, transmission losses and off-season realities (shorter days and lower angles of incidence) that result is massive drops in output during the winter months when power is most needed.

    All we in the real world of energy production ask is apples to apples comparison and real world engineering and ‘TCO’ cost data.

    • Bob_Wallace

      Nuclear has backup, storage and transmission costs.

      Coal has backup, storage and transmission costs. Plus expensive external costs that we pay through tax dollars and health insurance premiums.

      Both nuclear and coal have considerable “clean up after them” costs that will fall on taxpayers.

      If you want to talk about including storage and transmission costs for wind and solar make sure you also include the costs of integrating other electricity technologies as well.

      And make sure you use realistic prices for wind, solar, coal and nuclear. New:new and paid off:paid off.

  • J_JamesM

    Whatever happened to those nifty solar panels that could supposedly convert infrared radiation into energy? This kind of reminds me of them.

    • Jens Stubbe

      They are still out there and being deployed. Just google Seebeck generator or reverse Peltier element.

      There is also plenty of products that explore that cooling solar cells increase their efficiency and use the excess heat to produce hot process water or for preheating water for CSP.

      At the end of the day I think that very high efficiency solar will find its own niches, which could be car, planes etc. where the area is scarce and energy need is high and expensively served.

  • Burnerjack

    Maybe I missed it. Where does it say what this new cell achieves? Where does it say what the new assumed theoretic limit is? Somehow I missed both of these most important pieces of information.

    • TinaCasey

      You are not alone! This is a foundational project that proves a concept with real hardware…now the challenge is to deliver the hardware in a commercially competitive form.

  • Yee Tat Ng

    While this is good news, I am not really excited about this news because solar is already working now. It is just a small part in an incomplete puzzle. Batteries still stubbornly refuses to catch up in terms of price and capacity.

    Wake me up when batteries catch up in terms of storage capacity and similar drop in price.

    • nakedChimp

      What you need higher storage capacity for at the moment?
      A fridge sized unit that stores enough energy to get you through a day of usage is pretty decent.

      Price wise you’re right.. but that only comes down by scaling production up and they are doing that right now, scaling early adaptor demand up at the same time is a bit harder.
      You’ll at best have a nap, not more.

    • TinaCasey

      Check out flow batteries.

      • CU

        Tina, At least I would like to read a review article about the state for flow batteries. How many have been installed the last year and what is the reception by the users; mostly utilities I believe?

      • I think we really need to develop the solid state battery. No liquid electrolyte to freeze or overheat and chances are, will last as long as the panels, requiring less overall energy input from the panels and wind turbines for their manufacture (when FFs are outlawed).
        RE has to be able to power the world and it’s own collection and storage manufacture, less we all fry in a overheated biosphere.

    • globi

      Besides that heat energy can be stored cheaply (fridge, air conditioning, hot water): The world has already more hydro power storage capacity than is needed.

      Why not benefit from the existing hydro storage capacity? Or do you also build your own Highway because you don’t want to share it with your neighbor?

      https://www.youtube.com/watch?v=MsgrahFln0s

    • JonathanMaddox

      There’s a limited market for on-grid power storage technologies as yet because fossil fuels are still burned on an everyday basis, and any surplus of renewable electricity generation exists only in limited geographical areas and lasts for relatively few hours of each year. There just isn’t that much emissions-free energy available to store, yet. Almost all of what we generate can be used to offset fossil fuels which would otherwise be burned in the moment.

      Do not forget that fossil fuels *are* stored energy, and that the technology to convert that storage to electricity is already the dominant incumbent power generation technology everywhere.

      When renewable generation is overbuilt to the point that its production frequently goes to waste, and fossil fuel power stations are frequently shut down altogether for stretches of many hours at a time, such that turning them back on for a few hours at night is comparably expensive with batteries to supply those hours instead, *then* we’ll see the market for grid storage really boom to a scale comparable with primary generation.

  • neroden

    The upper limit for solar cell efficiency has always been 100% (thanks to the Law of Conservation of Energy).

    All other limits were limits based on *assuming particular technologies*, which is a silly thing to assume….

    • nakedChimp

      Why silly?
      Technology has limits.
      Engineers and scientists aren’t gods.

      • neroden

        Silly because solar panel technologies have been changing very rapidly for as long as I can remember. My Dad remembers copper photovoltaics back in the 1930s. If we’d talked about limits based on those, solar would have looked really bad…

    • globi

      The urban area in the US is about 360 m^2 per person:
      http://www.demographia.com/db-uza2000.htm
      (Plenty of parking lots, roofs and facades on top of this number).

      Even at just 15% PV module efficiency that’s already 54 kW of PV power or about 100 doped Lance Armstrongs for every single person. I think this should suffice.

  • bsw

    Greatest way to increase the power efficiency of a solar panel is to stick in the sun. It goes up 10,000 fold. Then one that is a concept in a lab.

  • They need to develop the automation needed to make a few hundred thousand square miles of triple junction NASA style, along with the solid state battery. Then, we’ll have enough energy needed to power the growing world, desalinate water for CO2 sequestration and for its own manufacture.

    • JamesWimberley

      We can meet the needs outlined in your second sentence with existing technology.

      • I guess i need to do an exact math study based on ten billion people consuming whatever average watts required for lifestyle, all the other inputs and account for the energy inputs for additional capacity based on the inverse of capacity factor minus additional inputs from wind, etc (not all will be solar). It’s the ESOI of all them batteries (and we don’t have solid state yet) that concerns me.
        The sequestration part of it might add up to even more energy requirement than some other large sector, so, ya, will probably need to scale up solar and wind by about a factor of 100 (fossil fuels currently provide 59x what solar and wind according to the oil price widget listing btu since Jan 1st for various energy sources). Also looks like we might not add as much CO2 this year 🙂

        • TatuSaloranta

          Huh? Calculations on how much land area is needed if simply just using best existing PV show that amount is pretty small. For example see:

          http://www.techinsider.io/map-shows-solar-panels-to-power-the-earth-2015-9

          (but there are n+1 other explanations as well).

          Given also that conversion rate is already at around 20%, and obviously capped at very least at 100%, it is not at all clear that improvements would be transformational or necessary; at most they are nice to have and can speed up the process — not by reduced land area, but by further improving economics.

          The real bottleneck is not the conversion efficiency but inertia, amount of money needed (to forego usual 30-50 year lifecycle for power plants) and eventual need for significantly more storage or other intrusive methods (smart load) for handling increased generation rate variation.

          • nakedChimp

            Na, the real bottleneck is politics.
            Even the guys running the shows (or the puppets that look like they run the shows) have told us that – repeatedly.

          • TatuSaloranta

            It is way too easy to start the blame game, just like “the other side”. Instead of considering it multi-faceted problem where, yes, in some cases and areas elected officials are more part of a problem than solution, but in other areas (California, Denmark, Germany etc) more part of solution.
            Often bigger obstacle these days are utilities, who are more conservative (in old-fashioned sense of wanting to curb change and move more slowly) in their view; and for them it is indeed all about (a) money and (b) technical aspects of doing their job (reliably and efficiently produce energy), and very little about general politics.

            My point is that building enough RenEng fast enough is a bit challenge from multiple perspectives, and blaming all on “politics” is just very naive and counter-productive.

            And guys who are telling all this tend to be “Some anonymous dude on the Internet”, as far as I see it. 😀

          • The real bottleneck is in how much extra energy is needed to make the required overcapacity necessary to make themselves 24/7 and their storage too. You see, the graphic you pointed me to did not include the extra build up needed to make up for solar’s capacity factor.
            Theoretically, if it’s CF is 25%, then we’ll need 4x the build up to make it work 24/7. Include the energy for batteries or whatever and i think you can understand my concern.
            Thankfully, we can ship the electricity from summer to winter in an instant (if we outlaw NIMBYism) which would require less of an overall capacity build up, less storage, and so, less output energy required for overall global decentralized and distributed RE structure.
            Better efficiency means more output energy for input (unless it’s manufacture requires proportionately more energy than today’s PV).

          • globi

            The hydro power lake have already enough storage capacity (Europe has already 200’000 GWh) and hot water as well as air conditioning can provide plenty of flexible demand response.

      • Craig Teller

        I would hate, on principle, to see new research squeezed out of the market because silicon dominates the market too thoroughly. Besides cost, that’s sort of what took silicon so long to take off because natural gas and coal had such a lock on power generation. You sound well informed on this. I would appreciate your thoughts.

        Obviously, given global warming, the faster solar is installed, the better, and yes, silicon is already here.

    • Mike Shurtleff

      Cost of production and installation is king. Single junction Solar PV is winning so far. Multi-junction with CPV and CSP are not.

      • neroden

        Single-junction will hit a price wall at some point where it can’t be made cheaper. At that point we will face flat module costs for 5-10 years until multijunction (with the price dropping along the same Swanson’s Law curve) reaches the same price level.

      • But it needs to be more efficient in order to completely replace FFs (better eroei allows for more energy input for batteries).

        • TatuSaloranta

          Why? At this point it would rather seem that cost efficiencies should be easier on storage side, grid connections and/or load-shifting. And for solar PV almost anything else other than panels themselves: majority of costs are now other system costs from installation to inverters and grid integration.

          • It’s not (really) about the economics, it’s about how much fossil fueled energy is required to make the panels and the batteries.
            Once FFs are outlawed, we will have to make all this from itself. In fact, pretend that they are outlawed already and try to make a total global RE infrastructure. This is what we have to do within the time span of 2 degrees C.
            Therefore, if the panels are more efficient, chances are, it’s energy input for manufacture might require a lesser percentage of output energy. Remember that some of the output also has to be used as input for proper battery and other storage.
            This is all I’m trying to say here, that we had better make sure that RE can make itself. Not yet, but within the short amount of time we have concerning our carbon budget.

          • TatuSaloranta

            Ok.

            Just for fun, let’s consider “energy payback time”; amount of time it typically takes for a plant to produce enough energy for its full lifetime emissions, from manufacturing to installation and eventual decommission.
            For wind turbines it is estimate as something like 5 – 9 months; for solar possibly slightly longer. For example:

            http://www.nrel.gov/docs/fy04osti/35489.pdf

            claims 1-4 years, but that may be out of date. And here at CT:

            http://cleantechnica.com/2013/12/26/solar-energy-payback-time-charts/

            from 6 months to 3 years.

            And this with just current crop of panels. It really is not very long time, and I am not sure this part is all that meaningful in context of energy transformation. It is FF plants, ICE cars, heating that pollute most. Not manufacturing of PV modules or components.

          • That’s exactly what I’m considering, aka EROEI. Also, ESOI (energy stored on energy invested) and the inverse of capacity factor. These three metrics start to add up real quick during wintertime.
            I believe, since wind has a better EROEI, it could better offset the rather poor ESOI of batteries. And, hopefully, a longer lasting (and still efficient) battery will be developed soon.

          • Bob_Wallace

            Forget EROEI. It’s not important when we’re talking about renewables. By definition we won’t run out of renewable energy for a few billion years. EROEI was something we needed to worry about with fossil fuels as sourcing became more difficult and required more energy to extract and refine.

            Just look at the price of solar panels and wind turbines, or the cost of electricity coming from them. If the cost is low then, obviously, there must not be a huge amount of energy embedded. And look at cradle to grave embedded energy payback. 3 to 8 months for wind turbines (depending on wind resources where installed ) and less than 2 years for PV solar panels.

          • You can not just forget about a fundamental physics metric. As long as people are willing to use less energy at night, then RE will do alright. However, if everybody wants power at night (and also wants to charge electric cars) and if the Eroei is 10 and the Esoi (storage), the capacity factor 20%, the round trip efficiency of storage, 90% and the integration is from only a few hundred miles, then you will get an overall Eroei of only about 1.2. That is not enough, as it will eat up profits.
            Add to the equation that we need MORE electricity to develop the world up to our levels and we need some serious initially high Eroei !

          • Bob_Wallace

            Why are you thinking about oil and coal? We’re not going to run out of sunshine and wind. There’s no friggin’ way we’d use up all the available energy that’s all around us every day.

            Toss out those letters, That E, the R, the O and the I. They have nothing to do with the future grid.

            And don’t worry about capacity factor. It’s built into the important metric –

            There’s only one important metric. Cost per kWh.

            What’s the cost of a solar kWh?

            What’s the cost of a wind kWh?

            What’s the cost of storing a kWh?

            Got a load that needs power? What’s the least expensive way to fill it, wind, solar, or storage?

            (I simplified. Include hydro, geothermal, tidal, biomass/gas, and possibly wave.)

          • Bob_Wallace

            BTW, Robert, I don’t think you understand capacity factor. It has nothing to do with EROEI, it’s a measurement of average output over time divided by hypothetical output if the plant/farm ran full speed all the time.

          • The natural maw of diminishing returns will apply at some point.
            Capacity factor only has anything to do with Eroei if the energy generated is not enough to power whatever and to be stored for later, too. If the source is like fusion, there’s no need for storage but if like solar, could need as high as 5 multiples of capacity buildup which is the exact inverse of its capacity factor of 20%.
            The energy for batteries have to also be accounted for. If the CF is low, then even more batteries needed, as any winter home of grid solar setup attests to. Sustained lulls could exaggerate this physics problem by requiring even more than the inverse of CF to be built up and stored, but, in the future, this won’t happen, right?
            I would assume integration and lesser energy requirements at night to lower such high capacity buildup, though at still more monetary and energy expense than if the sun shines 24/7.

          • Bob_Wallace

            Robert, you’re misusing the term “capacity factor”.

            That makes your comment gibberish.

          • Repeat, if CF is low, more has to be built to make up for when not generating. To not understand this is to be a “gibberer”.

          • Bob_Wallace

            “Repeat, if CF is low, more has to be built to make up for when not generating. To not understand this is to be a “gibberer”.”

            Now there’s some world class gibberish.

            CF has nothing to do with time of generation.

          • Sure, the cost per kWh is the most important, however, we can not rely on NG as backup when the sun is down (there’s no wind around here). Therefore, we will need more solar and batteries. In the winter, exaggerate this truth. Now, IF we need say, 100MW average continuous electricity to charge up electric cars (at night) and for ALL the other things a town of about 10,000 people will need, then we’ll have to consider whatever multiples of whatever energy input required to make the panel – and the energy required to make the batteries. If the panels require only a tenth, no big deal at all in the summer for powering air conditioning. However, building an over capacity of say, for times just to power the local factory at night, will cost 4/10 ths energy (and that much more money). Plus whatever energy input for the batteries!
            A way to compensate is long powerlines (if allowable, perhaps “battery ships”?).

          • Bob_Wallace

            Where is it that has “no wind”?

          • Hardly ever a wind farm type wind in big bear. We need powerlines for wind, right?
            I say go full on global integration of RE and storage capable of powering the many cities 24/7. Fossil fuels are NOT an option.

          • Bob_Wallace

            Robert, quit posting nonsense.

          • I thought you were more civil than that. Please re-read and try to understand how the expenditure of energy is just as important as the expenditure of money, concerning the inverse of capacity factors, and storage. Without fossil fuels, it is even more important. Without fossil fuels, RE integration is key.
            It is NOT “nonsense” to figure a real world off grid solar energy system, and then extrapolate to the global proportions.
            Why not be honest (do you like NG back up? ‘Cause, that’s what’s happening). Opting out of a mathematical debate on the actual ability of RE to power everything with current battery technology and costs is also NOT an option, if we are to overcome the fossil free challenge. Now, I know we are still on the road there, but not even wanting to know the math, the very simple maths concerning the energy inputs required is ludicrous!

          • Bob_Wallace

            Robert, I’m not going to expend energy trying to figure out your meaning when you misuse words.

            Do I “like” NG backup? Yes and no.

            I like the fact that utilities are willing to close coal plants and replace them with a mix of wind, solar and NG. That lowers CO2 emissions and reduces air pollution.

            But I don’t see NG as a viable long term solution. We need to quit burning all fossil fuels.

            Reality is, grid operators will not turn off coal plants unless they have an affordable way to keep lights on. And right now storage is too expensive for mass grid storage.

          • Yea, i was just thinking about how great things usually begin with small steps wHich eventually add up, in this case, fossil free.

          • Jens Stubbe

            Wind turbines are not 5-9 month but more like 6-15 weeks and still dropping fast due to lower weight and higher capacity factors.

            Solar is a bit more complex because there has in the past been used chemicals that are both toxic and high potent GHG’s. Also solar is a lot of different technologies and still more different manufacturing technologies and come with greatly varying efficiency. Also solar tend to use much higher percentage of strategic materials like silver etc. per produced kWh and also have an appalling low recycle percentage because the cost of separating a solar panel for recycling is much higher than to source virgin materials.

            As with wind power EROI is dropping very fast and most of the pollution and health hazards are also fast becoming part of the past.

            For both wind and solar the time to deploy is also dropping very fast. The Danish wind value chain do not produce to order because it will cost them market shares. You can basically almost buy wind power as a commodity so from you make the decision till you are done with the project and have made EROI you can be within very few month.

            No other technology offers similar fast GHG effect and net energy deliverance.

          • TatuSaloranta

            Agreed. Lower estimated energy payback time may well be true for modern systems and latest estimates: I just included a commonly quoted conservative estimate, from 2014 (https://www.sciencedaily.com/releases/2014/06/140616093317.htm) as baseline.

            These quotes are good when arguing with occasional “turbines never even produce enough energy to offset their construction” misinformation (yes, I still see this occasionally on discussion boards); any number that’s within months, not multiple years, is enough to take discussion back to reality.

            If you have links to more up-to-date publications wrt energy payback times those would be great, both for wind and solar.

          • Bob_Wallace

            No fossil fuel energy is required to make either solar panels or wind turbines. Sometime back we passed the point at which we had enough panels hooked to grids to produce all power we needed to manufacture new panels. We passed that point with wind years earlier.

            There’s nothing involved, as far as I can tell, in the mining, manufacturing, installation and recycling of solar panels and wind turbines that must be done with fossil fuels.

        • nakedChimp

          It already is more economical ti install PV and wind than FF.
          This is not a technical problem anymore, it’s political.

          • My concern is not (really) about economics… read my post to TatuSaloranta.

      • TinaCasey

        You’re on to something. Variations in production and installation costs are one factor, another is the variety of local and regional resources and opportunities…the MIT project could lead to a solution that proves cost-competitive in though perhaps not in all.

    • Mike Dill

      I have enough room on my roof here in Nevada (with 20% efficient single junction PV) to produce about 3x my annual energy usage. It will be some time before the relative power advantages for double and triple junction pass the price disadvantages due to limited (and perhaps costly) sun facing surface area.

      • nakedChimp

        Just electricity usage or inclusive your mobility (0.3 kWh/km)?

        The electricity usage for my 4 head fam hovers at about 20 kWh per day at 15 deg south of the equator at ~700m above sea level.

        If I were to include driving I’d need an additional 40kWh per day.

        In this area this equals a pv installation with ~20kWp if I can charge the cars when the sun is shining.

        • Mike Dill

          Here in Las Vegas, Nevada (36 degrees north), I get about 1800 kWh per kW per year, or nearly 5kWh/kW a day on average. I only need about 10kWh per day for my driving, which adds 2kW of PV to my requirements.

          • nakedChimp

            Ah nice.. so ~5 hours instead of just ~3.5 that I can use here for energy ‘harvesting’ estimations from peak power.
            On the other hand I love my tropical rain-forest surrounding too much to be mad about that 😉

          • Mike Dill

            No rain = Great sun. Hot and dry, not at all reasonable in the summer. Only 105F today, and not yet summer.

  • Freddy D

    When will we see these multi-junction, thermal capture, or whatever making it to affordable, mass market modules? Seems like the modules on the market are still in the high teens or low 20s for efficiency. Would love to see this in production.

    • Omega Centauri

      As others have noted, this was really about breaking a theoretical barrier, not about developing something practical. If this is ever used, it will be as a trick to incremnetally improve the efficiency of high concentration concentrating systems. A field which probably can’t compete against lower efficiency flat panels.

    • Mike Shurtleff

      CPV has not proven cost competitive with 1 sun Solar PV.
      Maybe Morgan Solar will succeed?
      You may see low cost double junction Solar PV in the future. Who knows?
      Single junction Solar PV is still dropping in price. It’ll do just fine at >20% efficiency. We’ll see what happens in the market. Sometimes the solution that appears best from a theoretical view point is not the most economical and does not win in the market.

    • nakedChimp

      There will be improvements over the years.. but no breakthroughs any time soon.
      Expect 20% module efficiency to be the normal for the next 10-20 years.
      And that’s good enough anyway for the time being.
      A normal house will fetch you 10-20kWp or said the other way round 35kWh-70kWh per day.
      That’s enough to run a home and have enough juice to drive 2 EVs 33km-66km per day each.
      And if you can/have to charge at work during daylight it’s even better as then the power can come from bigger arrays or what have you.

  • sault

    With all this added expense, it’s probably still cheaper to just buy some triple or even quadruple-junction solar cells that can get over 40% efficiency. Even then, it would be very difficult to scale up production of any of these exotic PV technologies over the next 10 years for a price that’s even remotely competitive. If it could work out, we could generate about 2x the power with the same number of solar modules. That would be nice and be the final death-knell for coal power to be sure. In the meantime, silicon solar cells are doing the job just fine.

    • sjc_1

      We have had triple junction solar cells over 40% efficiency for years. Spectrolab has done great work in this area.

      http://www.spectrolab.com/technology.htm

      • Mike Gitarev

        Several hundred $ per watt looks not suitable for wide usage.

    • Mike Shurtleff

      CPV has not proven cost competitive with 1 sun Solar PV.

      • Frank

        The competition for CPV is solar + battery.

        • TatuSaloranta

          How does CPV store energy? Or did you mean CSP? I mean CPV can indeed achieve higher conversion rates and potential savings in some of the components (optical part being larger than receiver), but I didn’t think it has much in way of storage, or properties that would help.

          • Frank

            I confused my acronyms. I was thinking about concentrated solar with storage tanks.

  • S Herb

    One additional fact from the MIT News link – the wavelength converter operates at 1000 C (1800 F). Just to point out that we are really dealing here with concentrating solar systems and somewhat extreme material properties.

    • nakedChimp

      Now I get how that rolls.. you need those high temps to get into the area where you can emit photons.
      I was wondering how they do that at lower temps.

  • Termin8r

    Please do not make the assumption that the likes of Thiel and Trump see any value in logic, or even facts. They don’t. They only see interests and the way they can serve them best in order to ultimately serve their own.

    • Tim Pynegar

      What they maybe looking at are the number of new coal fired power stations being built around the world including Japan and wondering why they are being shut in the USA and Europe.

      • JamesWimberley

        Do you really wonder why coal has to go?

        As has been documented here, Japan is the only OECD country planning a significant expansion of coal generation, and is coming under a lot of pressure to change course. Germany’s often-cited new coal power stations were planned years ago as highly efficient replacements for old ones; total coal-burning capacity is not increasing and output has started to fall. The same effect is seen on a much larger scale in China – coal plants are still being opened, but as coal output and the capacity factor of coal plants are falling, it’s a game of musical chairs where the inefficient old plants get squeezed out. Vietnam has stopped plans for new coal plants, though this does not apply to those under way. India still officially plans a very large expansion of coal generation – but curiously enough, the number of the planned 13 Ultra Mega coal plants has been stuck at two for years, and ground has not been broken on new ones. The industrial conglomerates are sitting on their hands as coal stocks rise, waiting for demand to pick up. Meanwhile solar roars ahead, towards reproducing the German death spiral of falling coal capacity factors and financial losses. The world coal price is falling. Australian plans for new coal mines are on hold, almost certainly indefinitely.

        This is not a portrait of an industry in good shape, but of one facing impending doom.

        • Tim Pynegar

          I personally don’t question that coal has to be left in the ground but the comment was about Trump who I suspect would place the needs of US coal miners way above the environment and when he looks around and see’s other countries such as Japan, Germany, China, Bangladesh and so on either building new coal fired power stations or replacing old ones with new ones it’s makes the argument against him doing the same more difficult as it plays into his narrative that the USA is being hard done by while others take the easy route.

          • neroden

            Trump has a very strong record of just shooting noise out of his mouth, without any regard to reality. Like his “plan” to have Mexico pay for a border wall with the US? Suuuure.

            Unfortunately, Trump is a pig in a poke: since he contradicts himself on an hourly basis and lies routinely, there is absolutely no way to know what he’d actually *do*. Other than redecorating the White House in marble and gold leaf; I’m pretty sure he’d do that.

          • Frank

            Sounds like an honest and fair assesment.

          • Harry Johnson

            On the portico will be installed big gold letters saying Trump House.

          • Dragon

            Recently read an article that Trump’s campaign is nearly out of money for advertising. His real tactic has been to say the most controversial dumb ass shit he can to encourage free media coverage of his remarks and save his advertising budget. Of course when a presidential front runner constantly spews racist, violent, dumb shit to catch media attention, those racist, violent, dumb shit ideas gain more credibility amongst the population. Very dangerous.

          • JamesWimberley

            This narrative is complete fiction. The USA , historically the largest emitter, has a very unambitious Paris emissions commitment, compared to others. China is planning to shed 1.3 million coal mining jobs in the next few years (link). The entire US coal mining industry employs 93,000.

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