Most solar panels are 15% or better. The best residential cells are 22.2%[3], the commercial cells are 25.3%. The theoretical maximum efficiency of single-layer silicon PV cells is ~32%.
That's awesome. I remember always hearing 10% when I was a kid, which looks about right on that first chart, assuming it takes a few years before things are commercialized. It's terrific to see the march of improvements in efficiency.
Curious, what is on spacecrafts.
Maybe not really efficient at all, because weight and reliability is way more important out there, and also abundance of raw sunlight.
We used triple-junction solar cells on our satellite. If I remember right the cells ran somewhere around $100-$200 per square inch. I don't remember the efficiency, but they were left-over dumped cells that were donated to us by some group at NASA because they "expired" (they're kept under a nitrogen purge because they oxidize slowly and these had a leak, if memory serves, still worked great though) and a few were broken as they are more fragile than glass and are about as thin as a sheet of paper. They glow bright red when you forward bias them which you can use to visually detect dead portions of the cell/damage.
Usually much better (5-10%) as cost is no object, and they don't have the losses involved with the protective glass that terrestrial applications need.
I recall hearing the theoretical max was somewhere around 36%, though it could well be my memory is faulty. I think this was from a video from around 2005. Is this "theoretical max" going up over time or do I misremember?
86.8% is for an infinite number of layers with concentrated solar. 33.7% is the max for a single layer p-n junction, which is what most readily available cells are.
The most expensive, high efficiency cells, like those on spacecraft, are 3 layer. They are too expensive to be practical on Earth.
Multi-junction cells similar to these have so far reached efficiencies up into the mid-40% range with optically concentrated sunlight under experimental conditions, though such high efficiencies have not been reached in mass production.
Multi-junction cells represent less than 0.01% of annual PV cell production. About 95% of annual PV cell production is based on different variants of single-junction crystalline silicon, with current commercial cell efficiencies in the 16-25% range. The 30% cells for space use also sell for more than 1000x the price-per-watt of a simple 16% silicon cell.
A theoretical "infinite-junction" solar cell could achieve up to 68.7% efficiency under full-power illumination from the sun on a clear day, or up to 86.8% efficiency on a clear day under optically concentrated sunlight:
The experimenters combined two leading industrial techniques for high efficiency silicon cells (interdigitated back contact structure, like SunPower uses, and heterojunction cells using amorphous silicon, like Panasonic/Tesla use) to reach the 26.6% record.
A household in Canada would typically need more panels than one in Mexico. Canadian homes tend to consume more electricity and the Canadian rooftop will get less sunlight.
If you are space-constrained, like on a rooftop, 10% more power from the same area of panels could be significant. It's a step function. It goes from "not enough room for desired wattage" to "enough room for desired wattage" very abruptly. Once you've reached "enough room for desired wattage," further efficiency improvements matter much less. You don't care a lot whether you have 25% or 40% leftover roof space after installing the panels. Paying for further efficiency improvement is worthwhile only if it offsets enough costs elsewhere to lower systemic costs (from using e.g. less mounting hardware, less connecting wire, less installation labor.)
The higher the industry-average efficiency, the less of a constrained-space advantage there is for expensive, higher-efficiency modules. That is, SunPower had a more compelling advantage when they were selling expensive 19% panels and cheap Chinese panels were at 12%. But now that SunPower offers expensive 22% panels and cheap Chinese panels are at 15%, more households can now reach their desired wattage-per-roof targets without paying for premium-efficiency.
If you just want to zero out your household's annualized average electricity consumption, because e.g. you have a net-metered grid connection, adding batteries to a PV system will increase the expected financial time-to-payback. If you are off-grid you need batteries to use solar power after dark but should make every effort to cut your non-daylight power needs before sizing the battery system. Batteries are currently a lot more expensive per watt-hour delivered than the instantaneous output of solar panels. In an intermediate case, where you don't get full net metering but are still grid connected, there are a few but not many cases where household batteries yield positive financial ROI at current prices. You could make the numbers work for a modest fraction of Hawaiian households and smaller fractions of households in Germany, California, and Australia.
If your efficiency increases by 10% you get 10% more output. With a current efficiency of 10%, increasing it 10% would mean your now at 11% efficiency.
If we talk about an increase of 10 percentage points, we end up with with 20% efficiency effectively doubling the output (100% increase).
The title of the press release is "Scientists Design Solar Cell That Captures Nearly All Energy of Solar Spectrum". That title is not "Scientists develop new multijunction cell", but instead implies they've designed something novel.
First paragraph: "Scientists have designed and constructed a prototype for a new solar cell that integrates multiple cells stacked into a single device capable of capturing nearly all of the energy in the solar spectrum. The new design converts direct sunlight to electricity with 44.5 percent efficiency, giving it the potential to become the most efficient solar cell in the world."
That describes a multijunction cell, without mentioning that the idea is decades old. They describe an efficiency of 44.5%, without mentioning that other multijunction cells beat that efficiency years ago.
I think you need to reread the article. Mentioning multijunction cells in the fourth paragraph is not a sufficient description of prior art.
I just had my panels turned on. I love solar. It's still difficult to justify it short-term on a cost-basis, but I'm saving about a dollar a day after all things are said and done.
That being said, I'm generating my own electricity and my panels will run for a very long time. The best is cranking the AC and still watching the meter run in reverse during really scorching days.
I have built a system that cost just under $2k and should pay off in about 3-4 years (depending on battery lifetime). 2.4 Kw (8 panels) of used panels @ $.32/Watt, Charge controller, 3Kw inverter, transfer switch and 320ah@48v used Golf Cart Batteries. System is offgrid and supplies all my convenience outlets, kitchen and 240v circuits are on still on the grid. Panels are on top of free standing structures and being off grid permits are not required and only the transfer switch installation needed to be done by an electrician. Bonus is being offgrid it acts as a big UPS in a power failure.
This is a great plan. PG&E here in California forces solar customers onto a more expensive plan. If you can avoid that switch and use solar to dramatically reduce (but not eliminate) your total kwh load then you'll definitely come out way ahead, because you'll be on their cheapest tier.
California will be changing dramatically how it charges for electricity in the next few years[1]. I was talking to a person Tesla today about putting solar on our house and he mentioned in passing that Time-Of-Use Rates will be the default for everyone in California in 2019 by law (AB 327 in passed in 2013). For your net metering you will get credit/pay for power to/from the grid at the rate for the time it happens. A good up-sell for the powerwall. If the rates get way out of wack due to high solar input, one could do well charging your powerwall during the peak solar production hours (see duck curve [2]) and putting them back on the grid a 3-6 hours later.
Yes, most of the electricity I have generated has been what would have been tier 2 @ $.26 kWh, with the climate stuff going thru Sacramento atm I expect the price to go even higher soon.
I've wondered about the 'used panel' market for a while. Do you know why your seller didn't just increase the price of the property or move the panels? Does the second-hand price of panels decrease linearly with the amount of lifetime left, and how can you verify?
I got mine from a recycler, he said they failed inspection after installation for scuffs and scratches. Mine produce very close to spec. I have read that most panels degrade at about 1% per year, the ones I got were 3 years old. I checked them all to see that the open voltage was close to the specs when I got them, worked out great.
In the uk most solar installations get a generous subsidy for power produced. The fixed subsidy was set 5 or more years ago at e.g. 44p/kWh for a specific installed capacity.
The high price per kWh means it is economic for these places to upgrade their panels to newer ones that get closer to their rated output (e.g. in low light conditions etc). Hence the market for used panels.
Source: looking at the explanations on used panel shop's website - I think it is reliable.
Yes it's 10 years for me as well. Most of that is because we have a 30% efficiency hit because we didn't want to cut down a tree in our backyard that shades it for 2 hours a day during about 6 months of the year. Our system is also larger than our current usage, because we plan to use more (electric car, more kids, etc).
Another benefit to think about is you've effectively locked in your electricity rate. With some companies that might not be a big thing, but here in CA PG&E has been relentless with their rising kwh costs.
I pay on average about 10.3 cents per kwh and have a newer home that's very efficient at holding cool air (and live in a state where we heat more than we cool). For those reaons it's a tough sell for me. If rates continue to rise and solar continues to fall, we'll have a cross over that works for me probably in a few years.
It's not cost competitive for you at 10 cents. Why bother? I'd kill for that kind of price in electricity. Our total cost with solar is around 13c per kwh over 20 years.
You're in a good place. I live in a neighborhood with older homes similar climate. Lots of people are doing solar because it's cool, but ignoring windows and insulation.
We ran the numbers on our house with an energy audit and found that the return on insulation, an attic fan and window replacement was literally like 2-3x solar.
The other thing to look at is solar hot water. It's not sexy, but that has been high ROI since the 80s.
I'm assuming a 10 year payback equates to an annualized return of ~7%. Would you be paying cash for the panels or using financing? If the former, do you have other investments paying that much? If the latter, at what interest rate?
Right now it's a 20 year loan at 5%, $106 a month, but we're going to pay 50% of it cash and 50% HELOC for tax deduction purposes.
There's a 30% tax deduction one time for the total cost. My loan payment is less than my precious monthly power costs including taxes and fees ($15 a month to be hooked up to PG&E).
Remember to look at other below the line costs too... particularly with leasing there are cases where the homebuyers credit situation can make selling your home difficult.
One friend had to take a hit in the selling price as a concession to buyout part of the lease.
The pay off time for our system here in Hawaii was, if I recall, about 6 years, even though the price of installations is really high. The price of electricity is too, though.
>"This particular solar cell is very expensive, however researchers believe it was important to show the upper limit of what is possible in terms of efficiency. Despite the current costs of the materials involved, the technique used to create the cells shows much promise. Eventually a similar product may be brought to market, enabled by cost reductions from very high solar concentration levels and technology to recycle the expensive growth substrates."
We will end our reliance on fossil fuels not by forcing masses of people to change their lifestyles and inconveniencing them, but by developing green energy tech that is simply more efficient and cost effective than fossil fuels. Once this happens the transition away from carbon based energy sources will be swift.
Given the rate of progress, I believe we'll see widespread adoption of renewable energy far before climactic conditions on earth become dire for humanity.
When do you think we will reach 1/10th of our current GHG emissions?
2020? 2030? 2040? 2050? 2100? Plus or minus five years? Will we have a linear decline to that level? When do you think that decline will start? Is there a particular model you're thinking of?
What degree of GHG concentrations/temperature increase will be the limit of what you consider to be 'not dire for humanity'? Is it compatible with your expected model of GHG emissions?
Are the billion people living in the Indian subcontinent included in your definition of humanity, or are we talking about North Americans and Europeans? If yes, will we be willing to shelter environmental refugees from impacted areas?
I'd really love to believe that everything will turn out fine - but while I've ran into many optimists, I've yet to run into one that is willing to quantify the reasons for their optimism.
My guess is ~2070-2090 will see 20% of current fossil fuel use.
Boats and Aircraft are going to be hardest to transition and will likely make up a large chunk of that 10+%. Bio fuels may take some of this, but it really depends on overall demand for liquid hydrocarbons.
Electricity and home heating are going to change from market forces.
Cars have many options, but oil is going to get expensive (as in 2-3x current price not 10x) which will push alternatives.
Electric trains can take over most long distance trucking and shorter distance is easier to transition. This will be a fairly fast transition if oil spikes again in ~2030-2040 combined with some form of carbon tax.
PS: Plastics / fertilizer and other chemical processes are going to be the wildcard IMO. But, they don't involve burning carbon so they are also less important.
I was writing up a response to your initial guess of 10% by 2060, which was... Pretty dire. Past-the-Paris agreement, 2.5C to 3C warming dire.
20% by 2070-2090, on the other hand, is a lost cause. That would put atmospheric at 580 PPM by 2080. That's >4C of warming, if we don't hit any positive feedback loops.
I'm not particularly concerned about plastics. They can be synthesized from biomass.
Sorry, I got into a habit of submit then edit on HN because we used to get errors if you waited to long. I did not think we would hit 10% by 2060, but I hope we hit 40%.
Natrual gas has spiked, but it's realitvly speaking less of a global warming threat due to C(x) H(x) turning into H20 (x) + C02 (x) which produces less CO2 per heating vs just C into CO2 from coal.
So, while there are a huge range of predictions. What happens in the next 20 years is more important than what's going on 40 - 60 years from now.
Don't the inevitable methane leaks from natural gas create more of a GHG effect than the CO2 emitted from burning it? It's not just the environment disasters like in California, but everyday minor leaks.
Methane has a short half life in the atmosphere ~10 years ish and there is already quite a bit of it there. So, it's only really important when the amount released is increasing relative to the average released over the last 20 year. AKA if they cut release in 20 years then (ed: it's contribution to) temperature would drop fairly quickly. https://en.wikipedia.org/wiki/Atmospheric_methane
Note it does break down into more CO2 than the wieght of Methane because Oxygen molecules are heavy.
The real risk is if warming the arctic starts to release a lot of stored methane, which would be very bad.
In a few years the question will become "How to do geoengineering safely relative to the risks of warming?" The planet may be able to support 9-11 billion people with mostly renewable energy, but perhaps humanity will not get there fast enough to avert risk of hitting a positive feedback level that would commit humanity to far more massive and therefore far riskier geoengineering.
The planet is unable to sustainably support the current 7 billion people. The only way I see 9 billion fitting in here is if we switch to purely artificial stuff and eradicate all wildlife and their habitat.
The way I see it, the limit is at 1 billion people if we want to preserve current situation, and even less if we want to let the nature regenerate.
I don't dismiss the idea that we are past sustainable limits already. But the fact is that increased living standards have not caused commodities crunches yet. Also, stabilizing population is the first step toward a sustainable population level, no matter what the right number is for a world that thinks in terms of a "long now."
As far as planes go, an intriguing option is liquid hydrogen. Hydrogen has a large energy density by mass, which is why we use it in rockets. There have been proposals on how current airliners might be converted to run off of hydrogen in the near term[0] for short and medium distance travel. If we can get fuel cell electric propulsion to work at jetliner speeds there is even more potential, as fuel cells can be made more efficient than heat engines.
I think it would be much easier to use methane. Just as carbon neutral if you make it yourself, and doesn't have as many exotic engineering requirements.
I didn't know that about fuel cells though, interesting.
10% -> 2025; 20% -> 2030; 50% -> 2040; 95% -> 2050.
India/Africa are included there. I think 95% of potential GHG emmissions (not just indexed to today but to 'present time') will be crossed in like 2060 or so. Renewables are going extremely quickly. we are in the steep part of the s-curve and there is no reason to believe we wont' get a few doublings due to battery cost decreases and deployed solar cost efficiencies. The transition will be a lot faster than ppl believe.
By that plan, we'd be looking at ~21.6 years of current GHG emissions.
This will add ~777 GT of CO2 to the atmosphere. Which will put us at ~500 ppm CO2 (We just passed 400 ppm). That would be warming between 2.5C and 3C.
If you want to hit a 95% reduction in GHG emissions, you're also going to have to:
* Shut down every single fossil fuel power plant over the next 25 years.
* Build enough renewable/nuclear powerplants to replace all of our fossil fuel power sources, twice over. (Assuming we switch to electrical transportation.)
And, the elephant in the room:
* Halve all current trans-continental shipping and air travel. It is currently responsible for ~6-7% of our GHG emissions. (And if it were to grow unconstrained, would likely double in volume in the next 30 years.)
* While bringing our other emissions down to nearly zero.
We can clearly do all this, but it would require significant changes in our lifestyles - something that optimists tend to not be willing to accept.
Agreed. It is more dire than most scientists are willing to admit or the public are willing to hear. At this point I think the best hope is:
a) incredibly rapid adoption of renewables
b) a Manhattan project to find a way to pull carbon out of the atmosphere starting within ~1-3 decades, once it becomes beyond obvious we've already emitted far too much and the consequences of inaction are more than human civilization can bear
This is the craziest thing I've written in 2017 but: I sincerely believe we will have consumer fusion reactors by 2030 if not sooner. The work of MIT SPARC combined with graphene manufacture will make this a reality. Combine this with all the investment in battery load leveling and electric vehicles and you'll see a very rapid energy cost reduction and deployment. Probably 10 years once the design is functioning. As to the boats, these reactors are well sized for boats. My guess is ICE Air-travel will be completely eliminated for mass consumption by 2070 if not 2050, replaced by faster cheaper evacuated trains and electric short-range aircraft. The power density of li-ion batteries at roughly 350WHr/liter is not great, I'd wager we can easily get to 700WHr/liter with graphene supercapacitors utilizing a combination of 3D layering and fractal interaction. I've seen an experimental graphene supercap with fractal interaction at 1200Whr/Liter but it had a tendency to explode with only a few cycles. The normal graphene supercaps go like 100k cycles with no degradation, or 30 times longer than lithium ion cobalt (what tesla uses). We are so freaking close to cheap graphene it's ridiculous. That's the technology no one sees coming, it's just about to enter the productivity plateau. /end crazy person talk.
Electricity and transportation, which you often see in the headlines about progress about moving to renewables, are not the only GHG emitters.
Agriculture, deforestation, heating are also big sources. As far as I have read there has been a lot less progress in that area.
Neither the USA nor the EU are undergoing deforestation at present, and electrical heating can substitute for the vast majority of applications currently served by fossil-combustion heat. That's why most research and headlines about GHG reductions in the developed world focus on transport electrification and electricity decarbonization.
In poorer parts of the world, where automobile use is less common and/or fewer people have grid tied electrical service, deforestation and agricultural emissions make up a larger share of total anthropogenic emissions. But most of the world's anthropogenic emissions, and most of the low-hanging mitigations for emissions, come from geographic regions that commonly have grid tied electrical service and other modern amenities.
But those replacements, electrical heating and industrial processes, are also holes. Basically, if we replaced 100% of the current electricity production with renewables that wouldn't even provide the energy needed for electric vehicles. So we already have to go >100%. And then we need to overhaul heating and energy-intensive industries too.
And even if we get to that point we still would not be carbon-neutral due to the remaining sectors. And possibly due to new natural sources (permafrost) we're already locked into due to the warming that is already in progress.
So the point is that just inventing our way to replace the current grid with green sources is insufficient for meeting the climate budget within a few decades.
I think we're all making slightly different points. OP said "We will end our reliance on fossil fuels ... by developing green energy tech that is simply more efficient and cost effective than fossil fuels. Once this happens the transition away from carbon based energy sources will be swift."
You replied pointing out that electricity and transportation are not the only sources of emissions -- not sure if it was intended as a rebuttal because OP didn't say they were. I noted that electrical heating can generally substitute fossil heating, that the developed world isn't undergoing deforestation, and that agriculture is a much smaller source of developed-world emissions compared with fossil combustion. Neither I nor OP said or implied that "just inventing our way to replace the current grid with green sources is sufficient for meeting the climate budget."
We're obviously going to blow past the "safe" 2-degree-rise-by-end-of-century cumulative emissions target. In the long term, if complex civilizations survive, I expect large scale atmospheric carbon removal efforts (enhanced silicate weathering and similar). Otherwise feedback processes and anthropogenic emissions apart from fossil combustion are probably going to amplify ~4 degrees of end-of-century warming to more like 7-9 degrees of warming by end-of-millennium. After that it'd take ~100k years to restore the pre-industrial atmospheric CO2 concentration status quo by natural sinking mechanisms alone.
Climactic conditions will always be a problem. The next headache will be how to deal with a heat bath from uniformly dissipated waste heat from this energy rather than natural gradients and storage that drive climactic processes. When greedy humans get their hands on 'unlimited energy' that is not a panacea, but a much bigger catastrophe waiting to happen.
If humans really had "unlimited energy", we could air condition the entire world, and send the waste heat to space with large infrared (or even visible light) radiators.
At some point potentially soon if you want really good economic growth you have to decouple economic growth from energy growth. That is a step more fundamental than decoupling energy growth from coal and oil.
Not really. Air conditioning is a heat displacement system, so you'd still have the same amount of heat. Using infrared radiators would just accelerate global warming since green house gases mainly absorb infrared light.
Visible light would probably be a hazard. Would be pretty great for "beam in the sky" special effects though.
It's heat, you can't send it anywhere except by thermodynamic processes. You can't beam heat to space. A beam of infrared is not heat, it is high quality free energy.
"Survivorship bias or survival bias is the logical error of concentrating on the people or things that made it past some selection process and overlooking those that did not"
That depends on the nature of the threat. Running out of feedstock for plastic? Not a problem. That's the sort of thing for which one can assume a technology fix will happen, and there is probably plenty of time. On the other hand, missing the population slow-down projections and ending up with a 20 billion population? That's doom, and there is no techno-savior.
"Dr. Ehrlich was so sure of himself that he warned in 1970 that “sometime in the next 15 years, the end will come.” By “the end,” he meant “an utter breakdown of the capacity of the planet to support humanity.”
So... by 1985, we will all be dead because DOOM!!!
Time and time again...
Now... can we all "get along"? Christians, Muslims, Chinese, Russians, etc? THAT isn't a technology problem - that's a humanity problem.
Can we feed everyone? We sure can... and advances in tech continue to push the envelope and there is no reason to believe that we can support many multiples of what we have now.
Is there an upper limit? Undoubtedly... are we near it? Hardly...
A population that's 2X the fairly optimistic projections of global population growth slowdown roughly double energy needs, at a time when, at best, renewable energy faces both enormous opportunity and enormous challenges in replacing coal and oil, and when cutting greenhouse gasses is critical to human survival. Just making that twice as large a challenge is reckless and dices with extinction.
I always wondered why we did not just use prisms to separate the different wavelengths, then capturing selections of the spectrum with a variety of simpler, unstacked panels. Perhaps one could even deflect the infrared into a more conventional, presumably more efficient, heat collector while the higher frequencies are directed to true photovoltaics.
Think of how solar is an investment: you pay money up front, use up a certain chunk of land, and you get energy over the next 25 years. Imagine panel A which costs $100 and has 22% efficiency, versus panel B which costs $500 and has 30% efficiency. No point in buying panel B, since you can buy 5x panel A for the same price.
I'm doubtful that land area is really a significant cost for most solar installations. Small ones go on rooftops that people already have, and large ones go on marginal land in the middle of nowhere that's cheap.
If there's someone with knowledge of the numbers, I'd be interested to be shown otherwise.
You are correct. "Small" utility-scale solar projects of 1-20 MW capacity take 7.6 acres of land per megawatt-peak, for fixed-tilt ground mount systems:
If you turned that land into a solar farm you could fit about 16 megawatts of fixed-tilt solar arrays on it. 16 MWp of installed solar equipment would cost $15.84 million at $0.99/watt and the land is $0.095 million. Land accounts for only 0.6% of the combined costs. (A 16 MWp farm is small by utility-scale project standards and probably would not cost only $0.99/watt because of dis-economies of small scale. I cited $0.99/watt to set a conservative bound on how much cost the land component represents in a utility scale solar project.)
If the cost is right, land won't be an issue. If solar tech were cheap and rugged enough, it could be added to paint, tarmac, billboards and many other artificial surfaces, even at very low efficiency. I've seen work in this direction with organic molecules (i.e. plastics).
I'm not optimistic about solar power being added to paint, tarmac, or just wherever you want. See for example the dumpster fire that is Solar Roadways. At this point, there's enough land / rooftops for proper PV installations that easily last decades, so trying to shoehorn fragile PV in places where it has to withstand daily abuse, like tarmac, stinks of bad engineering.
Maybe that will change, but it doesn't need to change, because we still have plenty of places to stick solar.
Yes, to be clear I didn't mean the sort of rigid, silicon/glass PV panels we have right now; and solar roadways is evidence enough that it would be a bad idea.
I meant something more like a polymer, bought by the bucketful and mixed in as an additive.
As usual, cost is the issue. Both the cost of the optics, the cost of tracking, the cost of imperfect tracking, and the cost of the complexity in the design and installation.
I know some academic research labs have looked into arrays of microlenses & prisms, which sound interesting, but I haven't heard of any commercial products. Googling for micro prisms and solar cells will show you some projects.
Ultimately, I think it's just much easier to install a simple rectangular slab with two wires coming out. And the costs of solar cells are so cheap that they're probably comparable to the cost of the optics you'd want to lay above them.
I also imagine that balancing the current-voltage characteristics of the cells could be challenging when light at different times of the day has different spectra (e.g., you wouldn't want diminished performance in reddish sunsets).
What is it that makes solar panels cost what they do, ultimately? Not materials, right? Those are all basically sand and other not so special things. Labor? Isn't it mostly automated? Upkeep of the factories? Input energy?
Maybe it's just all those things together. But it sure seems like if we wanted to it wouldn't be that hard to ramp up production and drive costs down a couple fold. Not that I know how.
Ah, the good old "I know nothing about this but assume it must be easy"!
It's materials processing. They're only "basically sand" in the sense that glass or microchips are. The key step is purification of silicon, which is like distillation in the liquid/solid phase. It's very energy-intensive. This then gives you a solid cylinder of pure silicon.
A surprising amount of recent cost reductions have been due to making the cells thinner and making the cut as thin and clean as possible.
They are then run through some annoyingly toxic chemical processes, given an antireflective coating, have silver wiring attached, and packaged into a glass or polycarbonate fronted housing.
A lot of talk about solar trade has highlighted "unfair" competition from cheap, low-quality Chinese modules. But China also has companies making high-quality modules (LONGi, Jinko Solar, Yingli, and Trina Solar were identified as top performers in DNV GL's 2017 PV Module Reliability Scorecard, along with longer-established Japanese, Korean, European, and American manufacturers) and still making them cheaper than European/American/Japanese producers. The greatest difference is scale.
Recently-bankrupt American solar manufacturer Suniva is trying to get the US International Trade Commission to impose a minimum $0.78/watt price on imported solar modules:
Suniva made good modules. But it was manufacturing only 200 megawatts of modules per year. And its modules were not more efficient or durable than good imports. The large, high-quality South Korean manufacturer Hanwha Q CELLS is guiding 5500-5700 megawatts of shipments this year. The large, high-quality Chinese manufacturer Jinko Solar is guiding 8500-9000 megawatts this year. American solar manufacturers can't turn a profit so they don't scale up. And they don't scale up so they can't turn a profit. Jinko Solar and Hanwha can stay in the black at price levels that will bankrupt small producers lacking the same economies of scale.
Not that I know either, but the quality control process is possibly a source of much cost of production. Every part must pass a series of tests during and after production before deemed ready for sale. Every failure of a test costs time and money. These yield rates are either low with low cost manufacturing, or, high with high manufacturing costs. This could be part of it.
'The new design converts direct sunlight to electricity with 44.5 percent efficiency, giving it the potential to become the most efficient solar cell in the world.'
it's sad that nothing more has been published on that architecture for 2+ years...
One would imagine most of the research dollars being into how to make multi-junction cells cheaply, rather than into other much lower efficiency cells.
"The only figure of merit in a PV system is cost per kilowatt-hour installed". Multijunction cells require concentrating panels and two-axis tracking. In order for them to make economic sense, both the panels and the tracking have to have lower lifetime costs than standard untracked panels.
So far, they don't. Plus, concentrating panels don't work under cloudy skies, so...
>"The only figure of merit in a PV system is cost per kilowatt-hour installed".
This doesn't make intuitive sense to me. If you could pay $50 for a bucket of goop you can slather on your roof that would capture 1% of the incident light energy hitting it forever, would everyone do so?
by your standard "hell yeah" as that means the equivalent of $2.5k per roof (I multiplied the $50 for 1% by 50 to conpare apples to apples) to capture 50% of the energy which is far better $ per KWh than offered by anyone else!
The issue is that for many people they would prefer to capture more than 1% and they are willing to pay more per kwh in exchange for getting more kilowatt hrs. So they would prefer to pay a large premium, thereby showing that it really doesn't just come down to cost per KW-hr installed.
I'm a little confused by your argument, so I'll go through it one clause at a time.
If you could pay $50 for a bucket of goop you can slather
on your roof that would capture 1% of the incident light
energy hitting it forever, would everyone do so?
Sure? If you postulate a PV system that has much lower cost per KWh installed than has ever been achieved, then of course it'll make economic sense.
by your standard "hell yeah" as that means the equivalent
of $2.5k per roof (I multiplied the $50 for 1% by 50 to
conpare apples to apples) to capture 50% of the energy
which is far better $ per KWh than offered by anyone else!
Sure? You made the fictional system way, way better, so it's an even better deal now.
The issue is that for many people they would prefer to
capture more than 1% and they are willing to pay more
per kwh in exchange for getting more kilowatt hrs. So
they would prefer to pay a large premium, thereby
showing that it really doesn't just come down to cost
per KW-hr installed.
You are now talking about something completely different. Homeowners demonstrably don't care about the power conversion efficiency of their roof-- the penetration rate of rooftop solar is pathetic. People care about how much their electricity costs, and only install rooftop solar if gives them cheaper electricity. If grid power costs $0.10/KWh, and solar costs $0.50/KWh, then they won't buy it. Look out the window! Look at all the solar panels you don't see.
That's the argument from economics. The argument from product availability: regular planar unconcentrated multijunction cells for terrestrial use don't exist. You can't buy them, because there's no market for a $10,000 500 watt cell when $200 300 watt cells are sold. https://www.wholesalesolar.com/solar-panels
Concentrated multijunction panels for terrestrial use exist, but are only used in utility-scale installations, since you don't do two-axis tracking with rooftop solar. (Dual tracked solar panels cast shadows on each other, so they have to be spaced much farther apart, and consequently have bad space utilization)
The only figure of merit in a PV system is cost per kilowatt-hour installed. Right now, all rooftop solar installations are single-junction. If multijunction cells resulted in a lower cost per kilowatt-hour installed, then they would be used, but they don't, so they aren't.
I'm really confused why you don't follow my argument. Suppose instead of $50 for a 1% efficient goop, my goop only cost $1 but was only 0.1% efficient. That is five times more efficient per dollar but reduces your yield by 10x!
Do you see why nobody who wanted any appreciable amount of solar energy would put my "$1 for a roof's worth of 0.1% efficient solar collection" on their roof? They would naturally choose the "$50 for a roof's worth of 1% efficient solar collection" goop over that one (if those two were the only two choices), even though it's 5x worse per kilowatt-hour?
I hope this explains what I'm talking about. A lot of people want more than 0.1% efficiency because they'd like to collect more energy than that...
I follow your argument, I just don't think it matches reality.
In any system analysis, you have to consider all the relevant factors. If you wave away important factors for the sake of argument, you get the wrong answers, and end up in long arguments on internet forums, repeating yourself a lot.
Let's game out some scenarios using your numbers. The choices are between a $1 array that gives 100 watt-hours, ($0.01/Wh) or a $50 array that gives 1000 watt-hours. ($0.05/Wh)
Rooftop solar, grid power is $0.001/Wh: You don't buy either array, since neither is cheaper than grid. This is true for most of the industrialized world.
Rooftop solar, grid power is $0.025/Wh: You buy the 100 watt-hour array, since the power it produces is cheaper than grid power. You don't care about total wattage, since you can get all the watts you want from the grid. This is true of places where either electricity is expensive, or PV is subsidized. (Hawaii, Germany, etc)
Rooftop solar, grid power is $0.1/Wh: You do buy the 1000 watt-hour array, since it saves you from having to buy expensive grid watt-hours. There is no place on Earth where grid power is more expensive than both single-crystal and multijunction PV.
Rooftop solar, offgrid: Here you do strongly care about array output... but you're only offgrid in very rural locations, where land is cheap. In practice, off grid solar is never limited to just rooftops! If you need more watt-hours, you build bigger arrays, rather than paying five times as much per panel.
Space: You need every milliwatthour, and each gram of spacecraft costs hundreds of dollars anyway, so multijunction PV suddenly becomes price competitive.
your own third scenario analysis shows (grid power $0.1/Wh), if all rooftop options are cheaper than grid, a worse $/KWh would be chosen as long as it saved reliance on the grid.
You left something out of your analysis: people can have an ethical reason to assign a cost of $0.1/Wh to grid power, because they consider environmental externalities they're not paying for, to be something they actually are paying for. If forced to, they may use the grid, but they might treat its cost higher than the listed cost.
You've summarized things well in your second sentence: "In any system analysis, you have to consider all the relevant factors."
As both your and my analysis show, it is not simply the dollar per kilowatt-hour that informs purchase decisions.
If a certain cheap solar array manufacturing process was extremely toxic to the environment, the environmentalist might not buy it at any price.
The cell is assembled in a mini-module with a geometric concentration ratio of 744 suns on a two-axis tracking system and demonstrated a combined module efficiency of 41.2%, measured outdoors in Durham, NC. Taking into account the measured transmission of the optics gives an implied cell efficiency of 44.5%.
Since this is a concentrating cell, compare to the concentrator cell records tracked on NREL's PV efficiency records chart:
The current record for 4-junction-or-more concentrator cells is 46.0%. This isn't a record-setting cell even if the implied efficiency holds up under standardized test conditions.
This cell like all high-concentration cells is unlikely to see mass market acceptance on Earth. The module needs precise two-axis sun tracking to work effectively even under perfect clear-sky conditions. That's significantly more expensive than fixed arrays or single-axis sun tracking as used by conventional large scale PV. And there's a vicious feedback loop: since two-axis tracking is significantly more expensive, it doesn't get developed/scaled, so the cost gap gets even wider over time WRT its competitors.
But that's not actually the worst problem of high-concentration PV for terrestrial use. The worst problem is that HCPV can use only direct normal irradiance. Ordinary non-concentrating PV cells produce very nearly 25% of its rated output if it receives 25% of test-condition illumination under non-ideal conditions (due to some combination of clouds, air pollution haze, dusty glass, etc.) Concentrating cells will produce close to 0% of rated output under the same non-ideal conditions. Few regions have clear enough skies to work with HCPV, but those same regions tend to be dusty, which the concentrating optics cannot tolerate. Mechanical and optical complications make HCPV higher-maintenance than ordinary flat PV and more expensive to install initially.
That's why there were a dozen+ companies working on concentrating PV in 2008 and all of them are now bankrupt or have exited HCPV manufacturing. Eking out another cell-level improvement wouldn't have rescued the value proposition of their complete systems. The refined polysilicon price spike that made exotic technologies look briefly promising only lasted a few years and then it became clear again that crystalline silicon is very hard to beat.
In orbit you wouldn't have to worry about dust or clouds, to be sure. But keeping pointed exactly at the sun could still be a pain. As far as I know there are no spacecraft using concentrating PV for power, though spacecraft do commonly use multi-junction cells similar to these without concentration. Space applications are very conservative due to the high cost of hardware and the small fraction of the total budget represented by the PV power system. Cutting another 30% from PV system cost is outstanding if you're building utility-scale PV projects on Earth, but down in the noise if you're building communication satellites.
When there's a really good technical improvement in an area, and few compromises required to make the improvement, then the press release, the abstract, and the full article can be about equally informative to someone wondering whether or not the touted breakthrough actually matters. Here's an example with a genuinely impressive improved flow battery chemistry from Harvard:
When the good news is a mixed bag, like this article under discussion (high efficiency solar cell... but not a record setter and touted numbers required concentrated sunlight) then the abstract is more informative than the press release.
When the "good" news required severe compromises on one or more key axes, then both the abstract and the press release (if there is one) will usually hide the important compromises. It's fun to guess which common pitfall the reported advance fell into before you read the full paper that reveals the bad news not found in the PR/abstract.
Caveat: if the press release is about something that the general public can't contextualize easily -- metrology, basic research before applications, algorithms... -- then the press office rolls a die to randomly determine whether they should claim that the new advance may one day cure diseases, cure pollution, or make your cell phone run longer between recharges.
If the process to make this kind of solar cell can be lowered enough through scale then they should communicate this process to Chinese solar companies. I am sorry for my poor understanding of chemical process; if the materials of the solar cell are roughly the same then it would be quite easy for the existing manufacturers to actually switch to this solar cell production.
I cannot wait for the era of super cheap electricity!
Switching manufacturing from silicon would not be easy, likely this needs whole new process from scratch.
Also, as the article notes, they won't be available in large sheets but only small milimeter chips - which require light concentration and thus sun-tracking mechanism.
Why should research funded by American taxpayers be transferred to Chinese solar cell producers, and by whom?
I hope an American firm implements the underlying science into a manufacturing process, and any Chinese firms that want to use the process pay a fair and equitable license for the technology.
Well, I'm in favor of technological spread across the world, especially when it's beneficial to the environment or society at large.
However, Chinese solar cell firms have been dumping cheap and sub-standard solar panels on America for years in an attempt to destroy the American industry, so I am less excited about specifically Chinese solar panel firms gaining access to this technology.
I suppose it marks me as a bit of a chauvinist in this case but I would prefer if those who conduct themselves as adversaries do not also enjoy the benefits accorded a friend.
> dumping cheap and sub-standard solar panels on America
The country receiving the goods can refuse to buy if the quality is poor, or there are safety risks, or the workers are being exploited or the manufacturing process is environmentally unsustainable.
Poor countries have little freedom to turn down wealthy customers.
