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Japanese company develops a solar cell with record-breaking efficiency
- candiodari 10y agoI'm not sure I like this. It seems that we're very clearly in the area of diminishing returns when it comes to solar panels. https://upload.wikimedia.org/wikipedia/commons/4/42/Efficiency_chart_rev_05-2012.png https://upload.wikimedia.org/wikipedia/commons/4/42/Efficien... The conclusion of that chart seems to be : concentrated solar power (even on small scale) is unbeatable, and tops out (realistically) at ~40% efficiency. So now we should probably work on very, very cheap lenses if we want to advance solar panels, and quick ways to make small, very cheap panels.
- deleted 10y ago[deleted]
- Arnt 10y agoWhy? AFAICT, there are three ways to double the output of a solar cell: Double the area, double the efficiency, and move the cell to somewhere with twice as bright sunlight and install a cable. That one option presents intractable problems doesn't seem to matter very much when either of the two others are available.
- Tharkun 10y agoI suppose it's a matter of cost, which will likely depend on location. Cheap lenses might be more feasible in densely populated areas. A big, fat, copper cable attached to very large and very cheap panels will likely be more cost effective in sparsely populated areas.
- dotancohen 10y agoCheap lenses won't work for solar panels on a car, boat, or other vehicle.
- petra 10y agoArea isn't unlimited in the residential market, place is fixed and installation is expensive.
- contravariant 10y agoWell, really there are only two, capturing more sunlight, or capturing sunlight more efficiently. Since we need sunlight for other things as well it's better if we don't waste it, but right now that doesn't really seem to be a limiting factor (there are still plenty of roofs without solar panels).
- danmaz74 10y agoI don't know if we're already at diminishing returns, but to estimate that you need to compute the economic returns, not just the conversion efficiency. As yearly production escalates, even small increases to the "conversion efficiency"/"production cost" can yield high total returns on the investment.
- jacquesm 10y ago> As yearly production escalates, even small increases to the "conversion efficiency"/"production cost" can yield high total returns on the investment. It won't matter. Investment is hardly ever looked at in terms of total returns but only in terms of annual ROI as a percentage of the original outlay.
- danmaz74 10y agoBy "total" returns I didn't mean "lifetime" returns, but returns on the whole production to which the new technology can be applied (be it yearly, monthly, or whatever). My point is that, if we're building (or upgrading) bigger and bigger production plants, even a small improvement to the process can bring in big annual ROI.
- lovemenot 10y agoCheap lenses can provide far less concentrated light than similarly cheap mirrors, since the latter are not constrained by having to sit atop a solar cell. As long as space is not a major constraint, controllable mirrors in array should handsomely beat lenses.
- Tuna-Fish 10y agoThis is the current version of that chart: https://www.nrel.gov/pv/assets/images/efficiency-chart.png https://www.nrel.gov/pv/assets/images/efficiency-chart.png This cell is the blue dot "Kaneka". Multijunction cells are very expensive to make. The reason the multijunction cells in that chart all have concentrators is that without them, the cost is ridiculously too much to even consider. This particular cell is noteworthy because it is cheap enough that you can eschew the added cost and complexity of the concentrator and just use more cells and potentially still be cheaper.
- jacquesm 10y ago> potentially That's the operative word here. And that is far from a run race with this particular technology, it is going to be close enough that it bears watching but not so good that it is a slam dunk winner.
- nojvek 10y agoTo be honest it's a lot more economical to have cheap large mirrors on your roof directing sunlight towards a concentrated spot of PV cells of higher efficiency that are somewhat expensive. You could use some of that energy to have tiny motors that track the sunlight. This would net in more energy and less cost per square meter right?
- jacquesm 10y agoI've done a lot of experimenting with that. Here are some of the (surprising!) results: - you only need one motor to aim a whole array of mirrors if you're willing to make some exotic gears - the lifespan of the cells will shorten measurably - you will need to cool the cells if you don't want them to die very quickly - there will be a serious fire risk
- ballenf 10y agoAre there cells designed for higher intensity than others -- ones that can handle the extra light and maintain efficiency?
- petra 10y agoInsolight is a startup commercializing cheap plastic lens, that both focus and track the sun(hard to do with fixed lens, requires some optics magic). Panels made from those will have 36.5% efficiency, with only a 30% increase in total installation costs - that's their goal at launch.
- Brakenshire 10y ago> I'm not sure I like this. It seems that we're very clearly in the area of diminishing returns when it comes to solar panels. I don't follow this argument. The median panels used in actual installations have increased in efficiency from about 16% to about 18% over the last 10 years (while the prices have more than halved). First, the chart you link to is for 'hero' cells, using expensive technology to test the limits of a particular material, it is only tenuously linked to industrial production. There's lots of leeway for improvement in industrial production, which is what matters to the economy. Second, improvements in efficiency are only one part of cost reductions. In the time that the cost of panels has dropped perhaps 50 fold you're only talking about a 1/3 to 1/2 increase in efficiency. Third, there's always potential for other materials or structures to come to the fore. If we could find a cheap way of producing multi-junction cells then the ~30% theoretical efficiency limit disappears. So, there's plenty of scope for continued improvements.
- londons_explore 10y ago> If we could find a cheap way of producing multi-junction cells I really don't see why this is impossible. Hire a bunch of specialists, make robots build the cells end to end, then build a bunch of those robots. Anything a human can make one of, it should be possible to make a robot build millions of with zero incremental human labour, as long as you invest enough upfront for the robots.
- mangecoeur 10y agoA fundamental limitation of concentrating systems is they only work well with direct solar irradiance - it's very hard to concentrate diffuse solar rays coming from random directions, as you have on any overcast day. This dramatically reduces the potential generated power in locations that don't have consistently clear skys (i.e. most places). So a high efficiency flat panel with a promising route to commercialization and built by a reputable company is a great step.
- jacquesm 10y ago> A fundamental limitation of concentrating systems is they only work well with direct solar irradiance - it's very hard to concentrate diffuse solar rays coming from random directions, as you have on any overcast day. It's impossible. That said, every type of solar panel works best with direct solar irradiance, what you can get from scatter off clouds and on overcast days is a pittance even in the best situations compared with direct light. So this isn't nearly as big a step (yet) as it is made out to be, it may work out commercially but that is definitely not clear at this moment, and if it does work out commercially then it remains to be seen how much of that efficiency gain ends up reducing the per KWh installed cost of the panels. Any net gain of course is good.
- averagewall 10y agoEfficiency isn't quite the important thing for solar as it is for fuel burning engines since all the sunlight is used up at the same rate no matter how much power you capture from it. We could get much cheaper panels with no better efficiency and that would still be excellent. More important than energy efficiency is price per unit energy. You could have an inefficient but cheap solar cell that's more economical than an expensive efficient one (eg. active tracker vs fixed - the less efficient option is usually more economical). Though when installation costs dominate, then you really do want smaller panels so you can spend fewer man-hours nailing them up.
- _rpd 10y agoIsn't the conversion efficiency basically irrelevant except for specialized applications like spaceflight where every gram counts? 8% thin film solar cells will be the market winner if their marketplace ROI is superior - $ per Watt and lifetime.
- the8472 10y agoIf installation costs per m² dominate because moderately-efficient panels already are dirt-cheap then using a more efficient panels that are a bit more expensive can save overall costs if you can get the same power with fewer m² and thus lower overall costs. And even if you drive down installation costs so you can roll out cheap cells en masse you'll eventually run into a space limit for some applications. There's only so much sun-facing rooftop on each building.
- pjc50 10y agoAren't we at the stage where "balance of system" costs are starting to dominate: wiring, mountings, inverters, installation labour and so on? Or is that only true for house-scale systems?
- JoeAltmaier 10y agoOr very, very large arrays in space!
- rick_cheese 10y agoWill be interesting to see manufacturing yields but also efficiency losses over time, compared to cells made currently.
- spodek 10y ago> A group of researchers funded by a Japanese government program develops... Sadly, a president believing global warming is a hoax means we Americans will keep reading about other countries passing us where we could lead. We private citizens will do our best, but we're swimming upstream. I don't mean to politicize what sounds like a great advance. I just can't help lamenting how it reminds me of our withdrawal from responsibility.
- xiaoma 10y agoThis seems like a pretty empty, flamewar-inducing comment. The news isn't even about the US and Japan has been dominant in high-end solar panels for well over a decade (as China has been the high volume producer). Why bring the US and its president of all of a few months into this thread?
- a012 10y agoyeah, why not when its president shows very clearly he doesn't give a damn on environment at all even before he elected.
- fratlas 10y agoI feel bad for American parents, trying to drown out the stupidity and teach their kids that if we/they don't change society drastically, CC will snowball.
- ythn 10y agoSuch arrogance. If the US isn't the front runner of all technologies at all times you can't help lamenting? "A group of non-American researchers funded by a non-American government program develops X" "Woe is us, we would be leading in X if it weren't for our buffoon of a president...!!"
- contingencies 10y agoZooming out a little, is it not true to say that minor efficiency gains in collection are still dwarfed in comparison to storage and current conversion losses?
- smdz 10y agoNo - because 2.7% (or 0.7 efficiency difference) increase is not insignificant when you scale up. As an analogy, think of what 0.7% tax saving would mean to you annually. In reality solar-cells and batteries are not at all cheap to install and maintain. We can scale up the solar cells and collect more energy. However, that needs more surface area to be covered with these panels. We still need better ways to store the energy efficiently.
- TillE 10y agoStoring huge amounts of energy is easy: use pumps to add potential energy to water. This isn't ultra efficient, but it's cheap and probably good enough. We have lots of experience with hydroelectric power.
- pjc50 10y agoDC-AC losses are small (<5% I think), and the majority of solar systems aren't connected to storage at the moment. Google ran a prize project to build a better inverter a while ago: https://blog.google/topics/environment/and-winner-of-1-million-little-box/ https://blog.google/topics/environment/and-winner-of-1-milli... "It had to have an efficiency greater than 95 percent and handle loads of 2 kVA. It also had to fit in a metal enclosure of no more than 40 cubic inches."
- jacquesm 10y agoThe highest efficiency for solar cells is at 46% already (multi-junction, concentrating). So this is not record breaking per se but record breaking for this particular set-up. Also: The best way to look at solar panel breakthroughs is to look at what actually makes it to market. If I had a dollar for every solar cell breakthrough that eventually did not make it to market I'd be fairly wealthy.
- itp 10y agoI think your comment is the first use of "breakthrough," to be fair. The article title and body refer to it as "breaking" the record. You are correct about the (vastly more expensive) multi-junction concentrating cells having higher efficiency, of course. You're also correct that not all improvements make it to market. Without research and continuing efforts to improve, nothing makes it to market. What's the point of your second paragraph? The article makes it _very_ clear that this is not in production, and speaks specifically to concerns about whether the process is suitable for industrialization.
- jacquesm 10y agoThe point is that you see announcements like these at a rate of 4 to 5 every year and hardly any of those ever make it to market. I've been active in the renewable energy-scene off-and-on for two decades and I really can't count how many times there have been announcements like the one here that did not go anywhere. It makes me quite skeptical of announcements like these, they do not really convey much in terms of information other than to create an optimism about solar panel efficiency gains that is usually met with disappointment when someone actually costs out a system and realizes that over approximately a decade we tend to see gains on the order of 1 to 2%. Hype simply doesn't help, at best this is 10 years away, worst you'll never hear from it again.
- philipkglass 10y agoThis paper is closer to industrialization than most and I expect production on scale in less than 10 years. It uses process steps that are already operating on an industrial scale. It's achieved on an industrial area wafer (compare with many academic records where cells are tiny, less than 10 cm^2). It's achieved on an industrial thickness wafer (some records use thinner wafers that are closer to the theoretical optimum, but those thinner wafers are too fragile to process industrially with current technology). It's just combining features of two cell concepts that are already manufactured on an industrial scale (interdigitated back contact cells and heterojunction cells). The core patents on heterojunction silicon cells expired just a few years ago so I expect more vanilla heterojunction and heterojunction-plus-other manufacturing going forward.
- syntaxing 10y agoTo put things in perspective, the current theoretical maximum efficiency for solar panels is about 34% [1]. There are a couple assumptions that are made to derive this number so there are ways to exceed this maximum efficiency. Though the assumptions made in the equations are fairly application to most solar panels product (not the ones made in labs). [1] https://en.wikipedia.org/wiki/Shockley%E2%80%93Queisser_limit https://en.wikipedia.org/wiki/Shockley%E2%80%93Queisser_limi...
- Retric 10y agoThere are already 46% efficient solar cells, the 33.7% limit is for a specific type of solar cell (single p-n junction) which are cheaper to manufacture. The maximum theoretical limit is ~86.8% for solar panels.
- seiferteric 10y agoIs the maximum theoretical efficiency I often see stated just for type of technology we use today (pn junctions)? Or is it a hard physical limit for any light -> electricity system? Would it be possible that some new technology for solar cells could be more efficient?
- averagewall 10y agoI think the highest physical limit would be Carnot efficiency for a heat engine driven by the temperature difference between the sun and the earth. (6000K - 300 K) / 6000 K = 95%. There could be a different lower limit we hit before that though.
- seiferteric 10y agoThat does make sense for an absolute upper limit, thanks.
- syntaxing 10y agoYeah, the limit only applies to single junction solar panels which I believe most consumer level solar panels and solar farms are this type [something I heard during graduate school, I have no source for this on top of my head]. I'm pretty sure the solar panel in the article is a single junction solar panel since they use PECVD (which is just CVD with a plasma generated above the wafer to improve uniformity) which allows them to get better results. Most double junctions require either MOCVD or even ALD but both technologies require longer fab time, have a higher reject rate, and the machines are almost 2X as expensive. Even then, the highest I've seen for solar panel efficiency product that you can purchase is around 32% and that is "state of the art" for today.
- cmrdporcupine 10y agoAround here it seems like solar installation companies are taking every decrease in material costs and increase in efficiencies and eating it up by increasing labour costs or profit margins. It always works out to a bullshit calculation that "the system pays for itself in 10 years" [if you ignore inflation, opportunity cost, and accept their electricity rate projections and assume the gov't won't cut green electricity subsidies]. That number never seems to change, it's always 10 years. I'd love to get panels put on my house and shop, I have a lot of square footage. But it seems like there's some very greedy middlemen between me and the panels and I lack the skill to install myself.
- Robotbeat 10y agoIf you "lack the skill to install" it yourself, then you don't get to complain about "very greedy middlemen." If labor really WERE super expensive and they were greedy, then you could afford to learn the skills and install yourself. Nah, don't expect labor costs to be free or expect labor to be paid below a livable wage. Or heck, don't expect labor which is more skilled than you are to be paid less than you are. But this is an important point: residential solar will always be fairly expensive due to labor costs. As module and other hardware costs reduce, it'll make sense to use the very highest efficiency cells, tracking systems (provided they're simple to install), etc. But I think utility and commercial scale solar will dominate. Someone will eventually get really good at installing solar farms a gigawatt at a time with a highly automated system. Think of the harvesting and planting machines we use in agriculture. Or the machines used to lay railroads automatically. When this happens, utility solar at the interconnection point will drop well below 1 cent per kWh in sunny locations, and transport costs will dominate. Which has some interesting implications.
- walrus01 10y agoYou're only considering grid tie when you say that a system won't really pay for itself in ten years. For off grid solar there are a number of places (example: very rural parts of ID and WA) where it might cost $40,000 to extend code compliant grid electricity from the nearest road to a new bare land property. And that is before you pay any monthly bills for ten years. Versus spending $35,000 one time on a big ground mounted solar system, charge controllers and a set of Tesla power wall 2 for battery storage. Cost and efficiency also hugely impacts developing nation solar (most of rural Africa) where no grid whatsoever currently exists.
- antouank 10y agoIsn't that a duplicate of https://news.ycombinator.com/item?id=13936480 https://news.ycombinator.com/item?id=13936480 ?
- daenney 10y agoYes. However: > If a story has had significant attention in the last year or so, we kill reposts as duplicates. If not, a small number of reposts is ok. This submission got traction, the other one was posted 12hrs ago and didn't really get anywhere.
- antouank 10y agoI didn't know that. Ok.
- deleted 10y ago[deleted]
- kolbe 10y agoWhat does this mean? Of the energy that all photons hitting the solar panel represent, 26.3% of it is converted into electricity?
- qntty 10y agoYes (for more https://en.wikipedia.org/wiki/Solar_cell_efficiency https://en.wikipedia.org/wiki/Solar_cell_efficiency)
- ihaveajob 10y agoFor reference, in https://en.wikipedia.org/wiki/Photosynthetic_efficiency https://en.wikipedia.org/wiki/Photosynthetic_efficiency there is mention that photosynthesis has a nominal efficiency of about 30%, but in practice the absorbed energy stays in the 3-6% range, with sugar cane being exceptionally efficient at 8%.
- the8472 10y agoThat 3-6% range is stored energy after the plant consumed some of the produced glucose to maintain itself and grow. Photovoltaics don't do that on their own, so you can't compare that to a solar cell's nameplate efficiency. Either you have to compare PV efficiency with gross glucose production or you need to compare the full PV lifecycle (production, installation, maintenance and recycling) with the harvestable sugar content.
- inetknght 10y agohttps://news.ycombinator.com/item?id=13939040 https://news.ycombinator.com/item?id=13939040 ~34% https://news.ycombinator.com/item?id=13938690 https://news.ycombinator.com/item?id=13938690 ~40% https://news.ycombinator.com/item?id=13938953 https://news.ycombinator.com/item?id=13938953 46% https://news.ycombinator.com/item?id=13939181 https://news.ycombinator.com/item?id=13939181 ~86.8% https://news.ycombinator.com/item?id=13939399 https://news.ycombinator.com/item?id=13939399 95% One... two... three... four... five theoretical maximums in comments. Something tells me that there's a lot more research to be done (or knowledge to be learned, at the very least) available here than we realize.
- marcosdumay 10y agoIt's not that. The 95% is the limit. You can't extract solar power with a higher efficiency. (Funny thing that you can extract energy from Earth, radiating it away, with ~99% efficiency.) 86.8% and and 40% are theoretical limits to some current technologies. The others are people debating what is the best available on the market (with varying definitions of "available").
- ythn 10y agoCould you explain why 95% is "the limit"? Are you saying 95.0% efficient solar panels are possible, but 95.1% efficient solar panels are impossible? What's the limiting mechanism here and why is it such a nice round integer?
- Normal_gaussian 10y ago> why is it such a nice round integer? Significant Figures [1] [1] http://www.bbc.co.uk/schools/gcsebitesize/maths/number/roundestimaterev3.shtml http://www.bbc.co.uk/schools/gcsebitesize/maths/number/round...
- smdz 10y agoThis is a good question - And this is a partial answer (from a link above): https://news.ycombinator.com/item?id=13939399 https://news.ycombinator.com/item?id=13939399 Not sure why you were downvoted. Seems like this community is showing signs of academic elitism
- Ulti 10y agoMedia is a few days lag behind academic publication on this one http://www.nature.com/articles/nenergy201732 http://www.nature.com/articles/nenergy201732
- jhallenworld 10y agoRectennas are another interesting possibility. The theoretical conversion efficiency is 44% according to this: http://ecee.colorado.edu/~moddel/QEL/Papers/Joshi13a.pdf http://ecee.colorado.edu/~moddel/QEL/Papers/Joshi13a.pdf
- nicholas73 10y agoThis is what I understand about efficiency after working with photodetectors (not used as solar cells, but similar in principle). 1. The sun emits a wide spectrum, with a long tail in the infrared. 2. Materials are only photoelectric at certain wavelengths. 3. The sensitivity to each wavelength depends upon design which is ultimately is related to the penetration depth of light in the material (longer wavelengths travel longer distances before reacting with the crystal structure). 4. Silicon is the most common and cheapest material, but its sensitivity rolls off sharply towards UV and infrared. Other materials are orders of magnitude more expensive. Not just in manufacturing, but the materials themselves. 5. To capture a wide range of spectrum you need a very long depletion region (kind of neutral area between p-n junctions). This has its own design tradeoffs. So the end result is that the real world efficiency limit can have many reported figures, from theoretical energy physics to practical material, design, and manufacturing limits. The biggest contributor to loss is that silicon is simply not able to capture much more than the visible spectrum. Next is that even with silicon there is a sensitivity curve (efficiency of converting photons to current per wavelength), and then designing so that you can capture the current (or else it would just recombine in the crystal). This is why gain in solar seems to be slow. There are tremendous limitations, and I have my doubts that there will be overcome any time soon. But, there is plenty of sunlight, so I would say the real challenge is energy storage. If sunlight can be stored cheaply and efficiently, then what we have is good enough.
- Zenst 10y agoI often wonder how good/cost effective optics would be, given the price of glass is cheap and that could be used to focus a larger area upon a small, more costly and yet efficient material. But as you highlight, cost and with that a balance of cost/return is a huge factor and whilst scale can help in many area's. It gets more detrimental with more expensive materials.
- nicholas73 10y agoI don't know the exact answer, but one should be able to calculate how effective this method would be. You are knocking out electrons from a crystal. Those electrons have to be replaced, so you are limited by the rate of replacement. Also heat generation from the current. My hand wavy gut feel is that optics wouldn't buy you that much. Silicon is orders of magnitude cheaper. To give you an idea, an infrared detector made of InGaAs about the size of a dime can already cost $5-10k. Solar cells of that size are priced in ... dollars? On the other hand, optics have been used for energy/storage in the form of a heating crucible. I've heard that promoted by some experts.
- jartelt 10y agoThere seems to be a lot of confusion about efficiency. For a single junction solar cell (like the type of solar cell talked about in the article) the theoretical efficiency is 34% (under 1 sun illumination). The best a silicon device can do is ~29% because silicon has a slightly lower than ideal bandgap. Single junction solar cells made out of GaAs have gotten to ~31% efficiency because GaAs has an ideal bandgap. However, GaAs is super expensive. Achieving 26% efficiency when the theoretical efficiency for silicon is 29% is super impressive. Engineers have basically squeezed every ounce of potential real world performance out of single junction silicon solar cells.
- stanislavb 10y agoAh, that's interesting. I didn't know there were a theoretical limit of 29%
- pizza 10y agohttps://en.wikipedia.org/wiki/Quantum_dot_solar_cell https://en.wikipedia.org/wiki/Quantum_dot_solar_cell Could you tune/adjoin these to span a very wide band of wavelengths?