Cheap solar cells made from perovskite promise 20% efficiency

 

Major advance in solar cells made from cheap, easy-to-use perovskite

Physicists boost efficiency of material that holds promise as base for next-generation solar cells

UNIVERSITY OF CALIFORNIA – BERKELEY

Solar cells made from an inexpensive and increasingly popular material called perovskite can more efficiently turn sunlight into electricity using a new technique to sandwich two types of perovskite into a single photovoltaic cell.

This first version of a new layered perovskite solar cell already achieves an efficiency of more than 20 percent, rivaling many commercial solar cells. Flexible and easy to make, it can produce more than half a volt of electricity. CREDIT Onur Ergen, UC Berkeley

This first version of a new layered perovskite solar cell already achieves an efficiency of more than 20 percent, rivaling many commercial solar cells. Flexible and easy to make, it can produce more than half a volt of electricity. CREDIT Onur Ergen, UC Berkeley

Perovskite solar cells are made of a mix of organic molecules and inorganic elements that together capture light and convert it into electricity, just like today’s more common silicon-based solar cells. Perovskite photovoltaic devices, however, can be made more easily and cheaply than silicon and on a flexible rather than rigid substrate. The first perovskite solar cells could go on the market next year, and some have been reported to capture 20 percent of the sun’s energy.

In a paper appearing online today in advance of publication in the journal Nature Materials, University of California, Berkeley, and Lawrence Berkeley National Laboratory scientists report a new design that already achieves an average steady-state efficiency of 18.4 percent, with a high of 21.7 percent and a peak efficiency of 26 percent.

“We have set the record now for different parameters of perovskite solar cells, including the efficiency,” said senior author Alex Zettl, a UC Berkeley professor of physics, senior faculty member at Berkeley Lab and member of the Kavli Energy Nanosciences Institute. “The efficiency is higher than any other perovskite cell – 21.7 percent – which is a phenomenal number, considering we are at the beginning of optimizing this.”

“This has a great potential to be the cheapest photovoltaic on the market, plugging into any home solar system,” said Onur Ergen, the lead author of the paper and a UC Berkeley physics graduate student.

The efficiency is also better than the 10-20 percent efficiency of polycrystalline silicon solar cells used to power most electronic devices and homes. Even the purest silicon solar cells, which are extremely expensive to produce, topped out at about 25 percent efficiency more than a decade ago.

The achievement comes thanks to a new way to combine two perovskite solar cell materials – each tuned to absorb a different wavelength or color of sunlight – into one “graded bandgap” solar cell that absorbs nearly the entire spectrum of visible light. Previous attempts to merge two perovskite materials have failed because the materials degrade one another’s electronic performance.

“This is realizing a graded bandgap solar cell in a relatively easy-to-control and easy-to-manipulate system,” Zettl said. “The nice thing about this is that it combines two very valuable features – the graded bandgap, a known approach, with perovskite, a relatively new but known material with surprisingly high efficiencies – to get the best of both worlds.”

Full-spectrum solar cells

Materials like silicon and perovskite are semiconductors, which means they conduct electricity only if the electrons can absorb enough energy – from a photon of light, for example – to kick them over a forbidden energy gap or bandgap. These materials preferentially absorb light at specific energies or wavelengths – the bandgap energy – but inefficiently at other wavelengths.

“In this case, we are swiping the entire solar spectrum from infrared through the entire visible spectrum,” Ergen said. “Our theoretical efficiency calculations should be much, much higher and easier to reach than for single-bandgap solar cells because we can maximize coverage of the solar spectrum.”

The key to mating the two materials into a tandem solar cell is a single-atom thick layer of hexagonal boron nitride, which looks like a layer of chicken wire separating the perovskite layers from one other. In this case, the perovskite materials are made of the organic molecules methyl and ammonia, but one contains the metals tin and iodine, while the other contains lead and iodine doped with bromine. The former is tuned to preferentially absorb light with an energy of 1 electron volt (eV) – infrared, or heat energy – while the latter absorbs photons of energy 2 eV, or an amber color.

The monolayer of boron nitride allows the two perovskite materials to work together and make electricity from light across the whole range of colors between 1 and 2 eV.

The perovskite/boron nitride sandwich is placed atop a lightweight aerogel of graphene that promotes the growth of finer-grained perovskite crystals, serves as a moisture barrier and helps stabilize charge transport though the solar cell, Zettl said. Moisture makes perovskite fall apart.

The whole thing is capped at the bottom with a gold electrode and at the top by a gallium nitride layer that collects the electrons that are generated within the cell. The active layer of the thin-film solar cell is about 400 nanometers thick.

“Our architecture is a bit like building a quality automobile roadway,” Zettl said. “The graphene aerogel acts like the firm, crushed rock bottom layer or foundation, the two perovskite layers are like finer gravel and sand layers deposited on top of that, with the hexagonal boron nitride layer acting like a thin-sheet membrane between the gravel and sand that keeps the sand from diffusing into or mixing too much with the finer gravel. The gallium nitride layer serves as the top asphalt layer.”

It is possible to add even more layers of perovskite separated by hexagonal boron nitride, though this may not be necessary, given the broad-spectrum efficiency they’ve already obtained, the researchers said.

“People have had this idea of easy-to-make, roll-to-roll photovoltaics, where you pull plastic off a roll, spray on the solar material, and roll it back up,” Zettl said. “With this new material, we are in the regime of roll-to-roll mass production; it’s really almost like spray painting.”

###

Co-authors are S. Matt Gilbert, Thang Pham, Sally Turner Mark and Tian Zhi Tan of UC Berkeley and Marcus Worsley of Lawrence Livermore National Laboratory, who produced the graphene aerogel.

The work was supported by the U.S. Department of Energy, the National Science Foundation (1542741) and the Office of Naval Research.


perovskite_mineral1

Perovskite (pronunciation: /pəˈrɒvskaɪt/) is a calcium titanium oxide mineral composed of calcium titanate, with the chemical formula CaTiO3. The mineral was discovered in the Ural Mountains of Russia by Gustav Rose in 1839 and is named after Russian mineralogist Lev Perovski (1792–1856) Image: Wikipedia

These solar cells use a synthetic form of Perovskite, not the mineral as shown above.

Perovskite solar cells hold an advantage over traditional silicon solar cells in the simplicity of their processing. Traditional silicon cells require expensive, multistep processes, conducted at high temperatures (>1000 °C) in a high vacuum in special clean room facilities. Meanwhile, the organic-inorganic perovskite material can be manufactured with simpler wet chemistry techniques in a traditional lab environment. Most notably, methylammonium and formamidinium lead trihalides have been created using a variety of solvent techniques and vapor deposition techniques, both of which have the potential to be scaled up with relative feasibility.

In one-step solution processing, a lead halide and a methylammonium halide can be dissolved in a solvent and spin coated onto a substrate. Subsequent evaporation and convective self-assembly during spinning results in dense layers of well crystallized perovskite material, due to the strong ionic interactions within the material (The organic component also contributes to a lower crystallization temperature). However, simple spin-coating does not yield homogenous layers, instead requiring the addition of other chemicals such as GBL, DMSO, and toluene drips. Simple solution processing results in the presence of voids, platelets, and other defects in the layer, which would hinder the efficiency of a solar cell. Recently, a new approach for forming the PbI2 nanostructure and the use of high CH3NH3I concentration which are adopted to form high quality (large crystal size and smooth) perovskite film with better photovoltaic performances. On one hand, self-assembled porous PbI2 is formed by incorporating small amount of rationally chosen additives into the PbI2 precursor solutions, which significantly facilitate the conversion of perovskite without any PbI2 residue. On the other hand, through employing a relatively high CH3NH3I concentration, a firmly crystallized and uniform CH3NH3PbI3 film is formed. Another technique using room temperature solvent-solvent extraction produces high-quality crystalline films with precise control over thickness down to 20 nanometers across areas several centimeters square without generating pinholes. In this method “perovskite precursors are dissolved in a solvent called NMP and coated onto a substrate. Then, instead of heating, the substrate is bathed in diethyl ether, a second solvent that selectively grabs the NMP solvent and whisks it away. What’s left is an ultra-smooth film of perovskite crystals.” In another solution processed method, the mixture of lead iodide and methylammonium halide dissolved in DMF is preheated. Then the mixture is spin coated on a substrate maintained at higher temperature. This method produces uniform films of up to 1 mm grain size.

In vapor assisted techniques, spin coated or exfoliated lead halide is annealed in the presence of methylammonium iodide vapor at a temperature of around 150 °C. This technique holds an advantage over solution processing, as it opens up the possibility for multi-stacked thin films over larger areas. This could be applicable for the production of multi-junction cells. Additionally, vapor deposited techniques result in less thickness variation than simple solution processed layers. However, both techniques can result in planar thin film layers or for use in mesoscopic designs, such as coatings on a metal oxide scaffold. Such a design is common for current perovskite or dye-sensitized solar cells.

Both processes hold promise in terms of scalability. Process cost and complexity is significantly less than that of silicon solar cells. Vapor deposition or vapor assisted techniques reduce the need for use of further solvents, which reduces the risk of solvent remnants. Solution processing is cheaper. Current issues with perovskite solar cells revolve around stability, as the material is observed to degrade in standard environmental conditions, suffering drops in efficiency. More here.

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119 thoughts on “Cheap solar cells made from perovskite promise 20% efficiency

  1. Interesting.
    The article doesn’t talk about the cost of perovskite vs polysilicon.
    We also need to see if the process is scalable.

  2. “20% efficiency”. Great, now we need is to capture the remaining 80% and I’ll be (mildly) impressed.

    Actually perovskite has much more potential as a use for storing high level radioactive waste in a synthetic rock called Synroc, developed in the 1970’s by Ted Ringwood at ANU in Canberra. Now that’s a good use of it and a useful direction for research for a change!

    • Did you catch that little bit of Plumbium in there somewhere ?? Seems like that’s a big oops.

      Well I’m impressed by their efficiency. I wonder why they didn’t report on this at the recently concluded Solar symposium at UC Davis sponsored by UC Merced Professor Roland Winston, but encompassing ALL UC sites with their own solar programs, besides Parovskites.

      Well so they need to just start making them and shipping them at competitive prices. Nothing improves performance and cost reduction than selling stuff in volume.

      In the silicon semi-conductor business, your costs seem to go down inversely with the TOTAL amount of product you have ever built and sold.

      So go for it Berkeley Maybe Elon Musk will buy your process for his Solar City PV panels. They are so proud of their low efficiency that it is a state secret.

      G

      • Oh, I’d be happy with 90%.

        The limit is still solar irradiance aka solar insolation. At the top of Earth’s atmosphere, this is about 1366 watts per sq meter, and it goes down from there. The other big issues remain variability caused by clouds, Earths rotation, dust, etc. Without cheap, high density energy storage, solar will remain a niche product. Currently over-produced due to subsidies.

    • Don’t worry about efficiency. Remember that crops and trees have ~1% solar efficiency and we use plenty of them nonetheless, including for energy use. lower efficiency just means greater surface to use, which is a non-problem down-there (only spacecrafts DO worry about surface…)
      On earth the thing to worry about is Watt per dollar. The rule of thumb is a 1W/$ thing delivers a 1 kWh at a price of 0.1 $.

    • Calcium titanate is a little expensive to use for storing things like radioactive waste. An interesting aspect of perovskite is that it is known to occur naturally in the earth’s mantle and in rocks some how dragged up to the surface from the mantle. There was some speculation that the conductive properties of perovskites might have important things to tell us about the planetary magnetic field, but that seems to have faded into oblivion in the last few years.

  3. Better hurry up before the LCOE of solar panels falls below 20 cents per watt. The bigger issue is BOS costs of labor etc. at construction sites, which now account for much more than half the installed cost. BOTs sending the panels down a long track on a large array are the way to go.

      • Rural population is in decline. That leaves Federal employees to administer the other vast tracts of empty land and bureaucratically foot drag any attempt to use it for solar.

      • Resourceguy November 8, 2016 at 2:26 pm

        Rural population is in decline.

        Surprisingly, that isn’t the case. The proportion of the population that lives in rural areas is decreasing. In absolute numbers, however, the rural population is actually increasing. It’s just that the urban population is increasing much faster.

        In 1960 the rural population of the United States was 54 million. In 2015 it was 59 million.

      • That’s one star for you Ozonebust. I think I made a mistake about seven years ago too, but then I could be mistaken about that.

        So Have a beer on my old chap you earned it.

        G

        PS I truly am impressed that they got this thing to 20%. I’ve been watching the OLED displays and the Quantum dot displays both of which are fantastic on 4K T&Vs. Haven’t made up my mind yet which looks better, but I guess both of them have to prove their lifetimes.

        Quantum dot phosphors potentially alter the LED game as well, but the longevity still looms over them.

        TV Displays and White LEDs need a red phosphor that is a very narrow spectrum red, maybe near 650 nm. Available phosphors go too far into the near 700 nm region, and the eyeball just sucks in the long red, so biting the bit on the blue to red Stokes shift loss is a double whammy for good CRI white illumination, and specially the warmer whites. Quantum dots can make a narrow red, but how long can they live??
        The 650 nm so called vanilla red LEDs of 60:40 GaASP wer chosen because the quantum efficiency drops as you increase P, but the eyeball gains as you increase P. For that system in those days the 60:40 gave the highest luminance.
        The Bell labs GaP LEDs using the Zinc Oxygen isoelectronic trap gave a red but it tailed all the way out to 700 nm and beyond and the eye photopic response was way down even though they were very efficient watts wise.
        GaAs is a direct band gap semi-conductor, but GaP is an indirect one, so the further you moved from the GaAs 900 nm IR the lower the energy efficiency but the higher the visible luminance until you got that magic red.
        But I don’t hold out a lot of hope for perovskites, other than learning some materials science.

        Good luck to them anyway.

      • Everybody has a rooftop…

        (solar solutions for shared apartments too).

        And old mine sites, old airport runways, over train tracks, multiple other places where solar panels are already in use.

        Plus solar film fittable to glazing of existing office building rolls out next year.

  4. Process cost and complexity is significantly less than that of silicon solar cells.

    Just need to see the details.

  5. Tin and lead are heavy metals that have to be disposed of properly when the panels reach their life-expectancy.

    I saw nothing here that indicates useful lifetime comparisons between the two technologies. Additionally, The moisture problem could make use in a marine or coasral environment a non-starter. Are perovskite cells worse than Si- cells in this regard?

    • Yes, much worse. These perovskites are hybrid organic/inorganic chemistries. The organic components have two problems. Super moisture sensitive, and natural degradation with continued light exposure. Silicon degrades also, but much more slowly. No mention in the PR about lifetime. Most likely because there isn’t any.

      • Silicon degrades also, but much more slowly. No mention in the PR about lifetime. Most likely because there isn’t any.

        According to Wiki:
        https://en.wikipedia.org/wiki/Perovskite_solar_cell

        The stabilization problem is claimed to be solved by replacing the organic transport layer with a metal oxide layer, allowing the cell to retain 90% capacity after 60 days.

      • Greg did you read what you just posted. Their lifetime fix will keep them good to 90% for 60 days !

        Wunnerful, simply wunnerful !

        But it’s low cost.

        How does that old saw go ?

        ” We have no quarrel with those who sell for less. They of all people should know exactly what their stuff is worth. ”

        I liked the Carl’s Junior advertising slogan. ” If our food tasted like theirs does; we wouldn’t bring it to your table either .”

        Carl’s Junior does deliver your burger fries and Coke to your table.

        G

      • Greg did you read what you just posted. Their lifetime fix will keep them good to 90% for 60 days !

        Yea … figured you could change them out every time you did an oil change on your car. Think of all the jobs that would create!

      • Lifetime? Well, the article read really well till the last sentence: “Current issues with perovskite solar cells revolve around stability, as the material is observed to degrade in standard environmental conditions, suffering drops in efficiency.“.

      • If they are moisture sensitive, how do you seal them? This was one of the issues with CIGS cells. Putting them in glass with hermetic seals might be possible, but what material could you use for the seals that is not permeable to moisture?

        90% capacity after 60 days would seem to have a rather short life.

      • ” Moisture makes perovskite fall apart.” Oh good then they can only be actually used under desert conditions and even then only if it never rains. Probably will show a stability problem with time.

    • Disposing of Tin is akin to removing Oxygen from the atmosphere.
      Tin is a very valuable material and reclaiming it beats out dispositating any day.

      G

      • Tin manufacturing may be viewed as adding oxygen to the atmosphere. It should certainly be recycled.

      • The value of Tin ($20k/ton) is manipulated – completely – and should be much less but there is a tin cartel and has been for 100 years. If the off-take increased the price would remain the same because it is already artificially high.

    • Come on, these guys live in university laboratories – practical questions are below them.

  6. Some observations from a former Board member of a failed solar cell startup. 1. Perovskites are a class of materials distinguished by structure, not chemistry. High temp superconductors are ceramic perovskites. 2. They are using some very expensive materials. Gold electrode, gallium nitride, graphene. Doesn’t matter in the lab. Does for commercialization. 3. All the other solar cell configurations involving organics have abjectly failed on cyclelife because of moisture sensitivity. Includes Gretzel cells and Konarko. OLEDs are also moisture sensitive and thatnproblem has obviously been overcome for commercial displays. But OLEDs don’t operate in outdoor snow and rain environments. Color me skeptical that this will ever see commercial production.
    Like Harvard’s rhubarb flow battery.

    • Heh, probably had trouble keeping folks from stealing the rhubarb and making strawberry/rhubarb pie (yum). :)

      • Rhubarb contains organic chemistries similar to the ones in the experimental flow battery. Slick Harvard marketing of a Ph.D thesis. Wrote up the example in essay California Dreaming in my 2014 ebook.

      • The election is distracting you from the world changing subject of perovskite solar cells? I’m shocked! Shocked I tell ya!! Shocked I say!!! :)

      • The election is distracting you from the world changing subject of perovskite solar cells?

        No worries. It has been so popular that CNN is renewing it for a second season. They’re even talking about making it monthly.

    • I had a hunch something like this would be said down-thread. But the true believers will now claim this as fait accompli, established technology.

      • “Our theoretical efficiency calculations should be much, much higher and easier to reach than for single-bandgap solar cells because we can maximize coverage of the solar spectrum.”

        Their figures are based on “THEORETICAL efficiency calculations” not measurements so its a model results, is it not?

  7. I worked in a facility that made polysilicon, a few of them actually. My understanding is that solar cell manufacturers would buy poly, put it in their reactors to make monocrystalline silicon and then manufacture the solar cells from the monocrystalline ingot…similar to the way IC chips are made. Poly, itself, wasn’t used to manufacture the solar cells.

    • SMC, silicon solar cells are available in both monocrystalline and polycrystalline types. The former are uniform deep blue black and have panel efficiencies as high as ~24% for the best (most expensive) ones. PolySi are mottled light blue, with best panel efficiencies ~17% at significantly lower cost than MonoSi.

      • Huh, ok. Learned something new. I just remember the poly whackers (no joke, that’s what they called them) coming in, in the evening, to break up, into chunks, and bag the poly ingots for sale to the solar cell manufacturers. The poly whackers would be leaving just as I would come in, in the morning. I spent a lot of time beating my head against the wall trying to get, and succeeding, eventually, some of the systems to work correctly.

      • You can clearly see the grain boundaries on polysi cells. Everyone of those grain boundaries would in an LED be called a non-radiative recombination site. Carriers combine (uses up current) but no photons are emitted. Poly si does the same for solar cells. Photons are absorbed but no electricity is generated at grain boundaries. Ergo poly si is worth what you pay for it.

        G

    • Indeed, reminds me of a tall story from my childhood.
      When US sent man on the moon, certain leader of a minor east European country (people were disposable commodity then) gathered his top engineers
      – we are going to send man to the sun
      – but he will be burnt alive
      – no problem, we will launch rocket at night.

    • but it works just fine in the day and many places have peak electricity use during daylight hours…

      Plus cheaper domestic battery storage is already here – estimated 4 year payback in Australia.

  8. But, But, they still don’t work at night and have reduced output under cloud and above about 45°N they are useless.

      • Hey, thanks to contributions(rebates, credits) from all of you plus renewable energy credits they’ve already paid off over 50%. Falling prices just mean it will be economic to replace them sooner rather than later.
        I’m just glad there are a lot more AGW believers than there are skeptics. Being an ardent skeptic I’d maybe feel a little bit guilty if that were the other way round. But Anthony has solar panels so I guess it’s OK.

        If perovskites can actually made waterproof enough for a reasonable lifespan cheaper would be even better.

  9. energy = needed;
    While (energy= needed) do;
    begin
    Plant trees;
    Burn wood;
    extract energy;
    if energy > whatisneeded then
    energy = notneeded;
    end;

  10. The intermittency problem is a major problem for the power grid at at ANY efficiency. The backup power must shift up an down with clouds, day and night, and the seasons. Yes, but the fantacy battery giga banks will fix that problem many say. Yes with fantacy unrealistic cost as well. To fix a non problem as CO2 is not controlling the climate.

    • Use of grid scale batteries for frequency response is already here and working. It is proposed solution for California grid/solar management.

      clouds aren’t an issue for widely distributed solar over a grid.

      The issue they do fix, is fixing a proportion of electricity cost for commercial companies. 7 UK car making plants have solar panels, for just that reason.

  11. In the photo, Perovskite is the deep red-black, rounded bits in the light brown matrix. I studied this mineral under the microscope often enough.

    • I noticed the sample was marked Arkansas at the lower right corner. I have seen tons of this around Hot Springs when my parents were retired there.

  12. What ever happened to Alvin Marks (inventor of polaroid film such as in Sunglasses) and his Lumeloid photovoltic film – supposedly 80% inefficiencies.

    • We could use Heinlein’s Douglas-Martin sunpower screens right about now. Put electricity into them and the panels give off light; shine light on the panels and they generate electricity (at very high conversion percentages).

      Too bad we can’t put LEDs out in the sun and get electricity from them…

      • The story element of Heinlein’s we really need to make solar practical is Shipstones, an arbitrarily high density battery that is stable and affordable. Pity some people fail to remember Shipstones are fiction.

      • People in Africa do just that -they put out their solar LED lights in the day and use them at night, meaning they don’t have to pay out each week for expensive kerosene.

      • Well, that’s not exactly what the sunpower screens did. In the story, if you pumped electricity in, you got light out; if you shone light on them, you got electricity out. Light AND electricity in one handy package, not a solar collector hooked up to a light source.

  13. This might be important. If this makes solar energy cheap enough, it won’t matter that some is lost by storing it for later in batteries.

    Of course real total costs (production, maintenance, disposal) versus total average energy production are the important questions here.

    • Kasuha, even if panel cost were zero it won’t help. There is still BOS cost (frame, installation, inverter). There is still nighttime electricity demand. No way does Tesla’s Powerwall solve the problems of battery cost and lifetime except with a massive subsidy scenario. And in low insolation geographies, you cannot get from here to there at all practically.

      • I thought my “total costs (production, maintenance, disposal)” was clear enough.

        If these cells provide energy cheaper than coal, they will be used instead of coal whenever possible. That’s perfectly normal, economical apoproach that has nothing to do with climate or greens. And people will be trying to find ways to utilize cheap energy over day and reducing expensive nighttime consumption when reasonable. A lot of current nighttime demand is artificial, created to keep energy consumption somewhat level over 24 hours.

        But whether they will be really that cheap is a big question. Perovskite appears to still have many problems, particularly with lifetime and degradation.

      • A recent study out of Germany and Switzerland showed that, with optimistic assumptions, solar PV will, over its lifetime, return about 82% of the energy it takes to build and install it in the first place. From the conclusion: “In other words, an electrical supply system based on today’s PV technologies cannot be termed an energy source, but rather a non-sustainable energy sink or a non-sustainable NET ENERGY LOSS.” It also states, “Our advanced societies can only continue to develop if a surplus of energy is available, but it has become clear that photovoltaic energy at least will not help in any way to replace the fossil fuel.” Here is the link: http://www.sciencedirect.com/science/article/pii/S0301421516301379

      • great contribution Randy Stubbings.
        Just spam it all over, and even propose that for publishing as article on WUWT. Otherwise it will stay covered up as so “inconvenient truth”.

      • Randy, that article confirms what I thought about photovoltaics in general for a while but is unrelated to perovskite in particular. It’s evaluation of currently commercially used photovoltaic cells, mostly based on silicon. Similar study or at least informed estimate for perovskite would be nice.

    • Many solar systems operate at about 17% average output of nameplate. If this increases performance by approx. 10% on nameplate you will now be at 18.7%. Better not tear down your fossil fuel/nuclear /hydro/storage too soon. And cost wise, whatever solar capacity is installed you can double the cost for the standard generating system that has to do the job for the 80% of the time that the solar system is useless. Watermelon economics. Or what we used to call stupidity before it became too popular.

      • Right now for us solar basically matches the airconditioner use. Our biggest single electricity drain is a large incandescent chandelier my wife tend to leave on for long hours into the night. If I can ever get her to agree to LED’s the usage will drop 200 watts. The rest of the electric bill is really not enough to worry about even if the cost per kWh triples. The line charges are larger, and more likely to go up.

  14. I have to augh whenever solar cell efficiencies are increased, leading the solar nuts to believe that THIS will make solar power grid-ready. Fellas, the problem with solar cells has nothing much to do with their efficiency
    or lack thereof.

  15. Another “advance” that might sort of work eventually. It still does not deal with the minor little fact that storage still sucks, with pumped storage the only real installed utility scale technology in use.

    • Correct. And owning a company with issued patents in the space, I can assure you there is essentially nothing hopeful for th future in the space. One possible exception for vehicles but not (based on currently available public data) for grid is newly announced Fiskers Nanotech. See very recent long guest post over at Judith Curry’s Climate Etc. for details. The tech is real, but no proof of scaleup yet. I think scaleup is plausible. Laid out the ideas for blog review.

  16. The problem has been, and continues to be, storage. Until battery technology advances to make solar a truly 24/7 alternative, it is just a fantasy.

    In lieu of sufficient storage technology, I suppose you could link all of the power grids on earth together and countries experiencing daylight would put their solar power on the grid…no thanks. Imagine how that system would be abused for political purposes.

  17. I’m confused (and that shouldn’t surprise you — I’m easily confused).
    The article states “The first perovskite solar cells … have been reported to capture 20 percent of the sun’s energy.” And “new design that already achieves an average steady-state efficiency of 18.4 percent, with a high of 21.7 percent… .”
    So is that 21.7 percent efficient considering the 20 percent captured, or 21.7 percent considering 100% of the sunlight that is available to the solar cell?

  18. Once there is efficient storage, solar could be fine. People will just have to realize that the plate capacity can’t be the planning capacity.

    To calculate planning capacity:
    First you have to calculate the blue sky output curve for the device site implementation. This means if it is a fixed emplacement, there are two penalties – one for the strength of the solar radiation vs angle off nadir and one for panel efficiency vs solar angle off nadir (looks a little like A*cos^2(angle) for angles between -90 (sunrise) and plus 90 (sunset) and 0 for all other angles – uses latitude to convert to hours and adjust the amplitude A). For a tracking type, you also have two losses, one for the fixed cost of the drive train(s) and one for the solar strength vs angle off nadir (looks like B + A*cos(angle) and 0 for outside of +/- 90). From this it is pretty easy to see that blue sky perfection means about 30% – 40 % of nameplate capacity maximum output.

    Second, you have to calculate the storage loss factor and conversion loss factors. These will be multiplied by the integrated output from the first step to get the REAL output factor.

    Third, as there are clouds, the site has to maintain sufficient surplus storage (which has to come off the top on production) to be able to maintain output even through large storm systems. This further reduces the amount the site can rationally send to the grid.

    These three factors mean that the realistic output rating of a solar plant with sufficient storage to maintain its output constant (ie grid-ready power) is below 20% of its nameplate rating. Without the storage component there shouldn’t be any solar sent to the grid at all.

    So if the EPA wants a TW of solar on the grid, they need to invent a really good battery system and install more than 5 TW of collection grids.

    • That second equation was supposed to be A*cos(angle) – B. Somehow I got to add the drivetrain use to the output…not quite the way it works! Perpetual motion here I come.

      • I fully agree. That is the reason this will not work. They keep tinkering with the generation side, but that is all pie in the sky until there is efficient storage. Even then, my objections vis-a-vis plate capacity go right over the head of most greens I speak with. Simple engineering is way beyond any of them.

    • “Once there is efficient storage”
      how many times should it be repeated … THERE IS efficient storage, RIGHT NOW.
      Nothing will ever beat pumped storage, very efficient and as cheap as can possibly be (this is after all nothing but a kind of hydropower, known to be the cheapest).
      Trouble is far more deep: a storage facility is nothing but a production facility
      1) with a “recharge” feature incorporated, which come at a price (but let’s suppose this price to be ~0, as it is with hydropower)
      2) that doesn’t produce of it’s own, but must rely on some other facility that do produce, meaning ->cost +100%
      3) that work on “real output” mode only ~half of the time, meaning double capital cost ->cost +100%
      TAANSTAFL !
      Without any loss, energy going through storage in bound to be ~3x costlier than direct energy. And in real life, is and will remain ~4x costlier.
      Storage makes sense as a buffer to dump variations and peaks, not as bulk.

      • The problem with pumped storage i9s that you have to put the reservoirs somewhere, and the environmentalists won’t let you put them anywhere.

        https://en.wikipedia.org/wiki/Scenic_Hudson_Preservation_Conference_v._Federal_Power_Commission

        The real problem is that gravitational energy is very difuse and weak. You have to move a lot of stuff to get enough energy out of it. Land use, siting, and construction costs kill it.

        http://physics.ucsd.edu/do-the-math/2011/11/pump-up-the-storage/

      • Sure enough, but that’s not the point. The point is, any storage system is bound to deliver power at 3~4x the normal cost ; which does make sense as a buffer to dump variations and peaks, not as bulk.

      • Norway has very little pumped storage, but it has a lot of hydro. It simply switches off some of its hydro generators when it absorbs surplus wind power from Denmark (and Germany, inc. solar, via the grid). That saves on the pumping. However, the problem is that there aren’t so many exploitable sites left, and available power depends on snow and rainfall – too little, and there isn’t as much backup, too much and excess water must be sluiced away, generating nothing – i.e. the power price drops to zero. Norway produces about 140TWh as hydro in a good year, 100TWh in a bad one (when they have to import, rather than doing it for profit). It’s not going to work as seasonal storage on a European scale.

  19. Storage can never be a solution. It is financially prohibitive to create enough generation facilities and storage facilities to carry through prolonged outages, whether solar or wind. You cannot know how many days the sky will be cloudy. You need massively extra production facilities to have excess that you can apply to the batteries. Storage is just a fantasy; a shiny object to distract the uncritical.

    You are dealing with weather; weather cannot be controlled.

    • But you have to explain in one and two syllable words why storage isn’t going to work over and over again or the emotive greens will never understand it. Most of them truly believe that solar and wind are magic energy sources that can never be tapped out. They don’t understand that the whole edifice of power to the wall plate is dangling from a string that can easily be snapped.

      I lived for a short while in a country which did not have 24/7 power supplies, where rolling blackouts were something you planned your life around. I never want to live that way again.

      • In Europe wind and solar complement each other, being strongest at different times of the year, plus there are good international HVDC links to bring power from other countries. There is a very good potential coverage of renewables which storage complements.

        I’d bet that in that country people now have solar and batteries to complement or replace their diesel generators and that one day the power outages will end. (did you know Germany has the world’s most reliable grid?)

      • Griff – you may think that wind and solar complement each other, and that interconnectors provide the solution along with storage. You should try doing some real numbers when you’ll find it’s just not true. Interconnectors are the saviour of Germany’s grid for now – but not for much longer. Neighbouring grids do not appreciate having to accommodate massive solar surpluses in mid summer, and are taking measures to block power flows from Germany that destabilise their own grids. If all countries installed plenty of solar, where would they dump their surpluses? In most of Europe, winter output from solar is negligible (average capacity utilisation across the year is about 10%, so those midsummer midday peaks are massive).

        So how about wind? Take a look here: http://mylly.hopto.me/windineurope/ and you’ll see it’s unreliable, even on a Continental scale. In winter we sometimes get blocking highs that last up to a fortnight, when wind output drops essentially to zero. There is no solar. It’s cold, and demand is at a maximum. The storage requirements to cover these things are truly gargantuan

        http://euanmearns.com/estimating-storage-requirements-at-high-levels-of-wind-penetration/
        http://euanmearns.com/how-much-battery-storage-does-a-solar-pv-system-need/
        http://euanmearns.com/is-large-scale-energy-storage-dead/

        Some realism for you.

    • In areas of the US where you run your AC for 6+ (in my case 9) months of the year, I don’t need storage: peak demand corresponds with peak production. It will go from my roof to my AC. This will cut my electric bill in half or better. My sister-in-law in San Diego has an array and rarely gets a bill, usually they break even or actually earn a credit. Now this is only economically viable in CA where the state puts their thumb on the scale, but would work in Texas if the free market is allowed to operate.

      • If only the true net value of “home” or “consumer” generated electricity were paid to the producer the economics are very different. The utility’s costs of accommodation should also be accounted for.
        As with all government tricks it is taxes and mandated overcharges to others, not thumbs, on the scales that yield your alleged outcomes.

    • But maybe we can camp without electricity easier, or reduce our grid dependence. Wind and solar are useful only on small scales at the individual consumer’s location. Feeding the grid from the generation side with them is absurd.

      • Germany also allowed thousands of its citizens to freeze,to death because of the huge electric bills they couldn’t pay because of the extravagant cost of “green energy.”

  20. Solar cells could be free and capture 100% of the down welling radiation as electrical energy, and they would still not provide power that is cheaper than current grid power.

    The inherent problems with solar are that the sun sets every day and that it is less bright in the winter than it is in the summer. This means that You must build a whole ‘nother system to survive the nights and winter days. Carrying the capital cost of two systems only one of which produces power and revenue at any time will break you.

    So, these types of stories are meaningless.

    • Agreed. While worthy for niche applications, this malarkey will never power my 4 bed, office, 5 bedroom house which needs aircon most days (Brisbane).

      I might put some on the boat, where there’s a decent bank of lead acid batteries to store some.

      • …by which time the batteries have worn out and must be replaced. Can you quote me a price on an automatic transfer switch with a 200 amp capacity? That is required by local and state elect. codes on any home service with automatic supplemental local generating input. I dealt with these issues for 35 years before I retired. Only magazine scientists and catalog engineers cannot see that these inefficient and complicated sources of power have very limited applications and pay back little of the original investment.

        One of the saddest decisions I was forced to make in my career as a university facility manager was to replace a 20 ton R-22 chiller for our research facility (which worked flawlessly) with a new high-efficiency R134a model. The higher pressures and variable freq. fan and compressor motors were a problem from the first summer on. We spent close to twice what we saved in electricity just keeping it going due to computer problems, component failures and vibration-caused refrigerant leaks by the time it was out of warranty.

        Another example is a 95% efficient propane furnace with all that technology will cost considerably more than a replcement 85% furnace for my house, yet all of my savings in fuel can be erased with a single replacement of a computer board or variable-speed motor drive.

        These are the fiscal realities of your high-tech fantasies which your progressive salespeople hope you find out after the purchase.

      • I also recall that Johnson Controls Corp. made an offer to finance a wind/solar project on the roof of our Clinical bldg. and despite my encouragement to give it a try, the director rejected it after speaking with the science and engineering dept. head, stating that our latitude and wind patterns were not favorable for profiting from such a project. He admonished me to “not get too excited at every sales engineer’s pitch that comes along”.

      • To tell the truth, Griff, my whole career was about spending tax money to save electricity and remediate sick building syndrome in mid-rise buildings not designed to have the HVAC shut down on humid summer nights and frigid winter ones. The quest for Carbon reduction has been an overly costly one from my experience.

      • While I’m ranting, consider that the funds wasted on a futile effort to reduce power usage and maintain operating integrity were diverted from improvement and remodeling funds which had to be made up from tuition and foundation funds, if the various departments wished to see them through.

  21. One of the biggest issues with all the new compounds is the junction between the new material and the material that actually carries the bulk current: How well does it stick to copper? Seems trivial, but isn’t.

  22. Perhaps there is something to this new technology… or perhaps this is just another example of a university PR department promoting an invention or process that will never amount to anything.

    Every few months there are university press releases such as this… and they never seem to amount to anything

  23. Cheaper solar cells – so what. Since solar panels represent typically about 15 % of the solar PV power plants installation cost to turnkey, it will lower the overall cost by a whole 1 %. Maybe.

  24. You can make a primitive pv cell using somewhat similar chemistry based on titanium. The main ingredients are icing sugar and tea. link

  25. “Promises”. Get back to us when it actually works. Real life works. Also, 20% seems a small amount of energy, especially since it only works when the sun shines.

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