There 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.
Admittedly, there still a lot of room for solar panel research for the upcoming years which is pretty exciting!
The discrepancies is often due to fact we're defining "solar panels" quite different for each application and also the definition of input energy is different.
A great example is engines. The theoretical (Carnot) efficiency is limited by the heat difference between the source and the sink. You can burn fuel at a higher temperature and pressure which will give you great efficiency, but it's not realistically possibly due to physical constraints (usually the steel that houses the explosions). That's why steel engines are often said to have a maximum fuel efficiency of 37%.
This same idea applies to solar panel but it's even more convoluted. What is input energy? Is it all the energy from the sun or is it only the energy within the energy band that the panel can "see"? What is efficiency? The efficiency for different energy band is different for each solar panel as well. Worst of all, this efficiency changes for different temperature and is effected by hysteresis! By the time you store the energy, you also lose efficiency depending on the internal resistance of the energy storage (That's why MPPT exist and fun fact of the day, from what I know, there is still no reliable analytical method to account for this. Most MPPT trackers are done empirically).
Sorry for the long rant, but yeah, solar panels are confusing and there is a surprising about of research that still needs to be done!
These things are well defined in the research community and they don't have any issues with this. The input energy is all the energy from the sun that is incident on the panel. Efficiency is electrical power generated by the panel divided by the power from sun (~1000 W/m^2). For the NREL efficiency records, the measurements are all taken at the same temperature at the NREL facility. To find the max power of a device you just sweep the voltage applied to the device and measure the current output and determine which voltage produced the most power (P=V*I). Then operate your cell at that voltage.
I heard about carnot energy but didn't realize the calculation was this simple. Suppose we say we get a insulated material that is string enough to handle high temperatures. We can beat the 37% right?
It's a partial yes. You have to worry about pressure as well. You can burn fuel at a higher temperature by igniting the gas at a higher pressure. But there are certain constraints due to the fuel. If the pressure is too high, the fuel will spontaneous combust. That's why there are different octane rating of fuels and why higher octane fuel gives you better fuel efficiency (given your engine has some sort of valve timing like VTEC). This is also why Diesel engines tend to have better mileage than gasoline engines. Even though gasoline engines will perform better at the same pressure as Diesel, there just no way to bring the gasoline to the same pressure that the Diesel can handle.
When and how you combust the fuel can give you different fuel efficiencies as well. For instance, the Brayton cycle can achieve easily over 50% fuel efficiency. But in order to achieve this, you need a special housing (jet engines uses this cycle) to be able to compress the fuel to the specific pressure and also handle the pressure. Also, special fuel is required. These two things makes it not really practical for the standard consumer.
On a tangent, Internal combustion engines is probably one of the funnest and hardest class I took in graduate school...
You can, but it's worth pointing out that cars don't really run on the Carnot cycle because, unlike your air conditioner, they're not reversible. Usually they use something like the Otto cycle. To improve efficiency you can change your cycle or push the limits (temperature, compression ratio, etc.). The current generation Prius apparently uses an Atkinson cycle and achieves 40% efficiency. Some F1 engines notably have a thermal efficiency of 47%.
It's mostly about the max temperature. If combustion in a steel engine runs at 250 C and operates in a 50 C environment, the max efficiency is 1-325K/525K = 38%.
Ceramic, for example, can operate at far higher temperatures, so in theory a ceramic engine can be more efficient.
However, ceramic is harder to work with, and not as durable as steel, so it's not a practical alternative.
> What is input energy? Is it all the energy from the sun or is it only the energy within the energy band that the panel can "see"? What is efficiency? The efficiency for different energy band is different for each solar panel as well
Don't research/industries usually come up with unambiguous terms and units for these things so they can compare metrics? e.g. Our prototype showed 94% VSE. VSE: "Visual Spectrum Energy" is the input energy between 400-650nm as measured by ... "
It's even worst than that in practice. I remember an article from many years ago where the author went through the actual efficiency of the various components in a gasoline-powered car. The conclusion was that the entire system was somewhere around 18% efficiency.
I can't remember the name of the article. It may have been in one of my engine/automobile design books. Don't know. Sorry.
When talking about solar cells, the efficiency is defined as electrical power produced divided by the solar irradiance on the panel (~1000 W/m^s without concentration). In this situation, the theoretical limit for a single junction solar cell on Earth is ~34% as shown by Shockley-Queisser in their detailed balance calculations. Multijunction cells can be more efficient than single junction cells and can theoretically reach ~70-80% efficiency if >30 junctions are used and concentrated sunlight is used. In practice it is prohibitively difficult and expensive to make a device with more than 4 or 5 junctions, so you will not see one sun efficiency greater than 70% in real life. The 95% number is for a Carnot engine and doesn't apply to an operating solar cell. In order to extract power from a solar cell, you need to operate it in forward bias (typically at the maximum power point). When at the maximum power point, the solar cell emits radiation and therefore has irreversible losses. This is why the real limit for a single junction cell is 34% and not 95%.
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").
Could 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?
And yet, you can take a solar cell out to Pluto where the mean temperature is 40K rather than 300K and theoretically get far higher efficiency than 95%. So 95% isn't really a fundamental limit.
Yep, I'm assuming the solar cells are on Earth. Seemed like a good assumption to make.
If you just send them into space with good enough radiators, you'll be able to get 3 9's of efficiency (mid way to 4). But you don't get to reuse the heat waste.
I thought it was more fundamental than that; to capture energy, there needs to be energy, if your wind turbine transforms all of it, there's no current anymore and the system will change phase.
"Consider that if all of the energy coming from wind movement through a turbine was extracted as useful energy the wind speed afterwards would drop to zero. If the wind stopped moving at the exit of the turbine, then no more fresh wind could get in - it would be blocked."
This is a fundamental limitation of turbines. Thus, a technological limitation for wind-power. Other technologies could have other limits.
Besides, that's a limit on collecting efficiency (how much you can collect / how much is there), not usage efficiency (how much you can use / how much you collect). You don't "destroy" the wind when your turbines don't collect it, it's still there.
A solar cell could never achieve the Carnot limit, so the 95% number is not relevant. In order to extract the maximum amount of power from a solar cell, must operate it at it's max power point. When you do this, the cell is in forward bias and must emit light (because of the physics of absorption/emission). Emitting light is a loss mechanism and thus people take this into account when calculating the theoretical efficiency for solar cells. It has nothing to do with currently available device on the market and is just accounting for how solar cells work.
This 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.
I 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.
I 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.
To 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).
There 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.
Yeah, 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.
Is 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?
I 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.
Around 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.
If 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.
You'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.
Interestingly, this applies on very small scales too. For certain street furniture like parking meters etc. it can be cheaper to install solar and a battery than to dig a cable.
In terms of city government unionized labor salaries and equipment cost, or hiring a contractor cost, it can be VERY expensive per meter to dig up an existing concrete sidewalk/curb and road to run code compliant AC electrical to a parking meter. Or something like a bus stop arrival time sign. Looking at $20,000 per unit in some cases, or more. And then there's the question of where do you get the AC power from in a built up downtown type area, you can't just tap into the nearest building, it usually involves dealing with the electrical grid for the streetlight system which was not designed to support thousands of small accessory loads hanging off it.
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.
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.
Without them, multijunction cells are less efficient too.
Leakage current, which happens even in darkness, wastes power at a fixed rate per unit area. By concentrating sunlight, one can generate far more than this leakage rate making it insignificant.
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.
To 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?
I'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
Yes, but they're not cheap, in fact they are so expensive that it will be cheaper to cover the mirrors with cheaper cells directly...
At this point in time there are no cheap and easy solutions in sight to make the next 2 to 5% gain in efficiency in a cost effective manner.
But given enough time and effort I'm sure that that will happen, I expect the final cut-off to be somewhere around 25% net efficiency (solar incidence to electricity out of the system) for smaller installations and maybe up to 30% for much larger installations.
Yes, there are different cell and cooling designs for low concentrating PV and high concentrating PV (LCPV, HCPV). But the price of non-concentrating PV systems has, so far, fallen fast enough to prevent either LCPV or HCPV from taking even 1% of the PV market. Soitec, Amonix, Suncore, and Sunfocus all failed to drum up enough CPV business to stay solvent.
Maintenance and installation costs already eclipse the panel costs. For any assembly you evaluate, you have to answer two questions:
Will this require more complex installation than flat panels?
Will this require more lifetime maintenance than flat panels?
If the answer to either question is a yes, it doesn't matter how good your system is in any other measure, you will lose against simple flat panels in total cost per electricity produced for any small-scale installation.
Correct. I found this out the hard way with my two leafs of 2x4 panels tracking the sun in two axis. By the time the system was up and running I could have had more power and less headaches by installing 24 panels statically on the roof. It would have looked better too.
Tracking systems with moving parts are expensive and complicated. With good quality 320W panels at $0.45/watt now in pallet quantities, going with a low cost fixed mounting system (whether ground or roof) makes much more economic sense. Considering the wind loading that a two axis tracking system which can hold 6x280W panels must endure, no wonder they cost a lot.
That sounds like the "more economical" is wiped out as soon as you have a maintenance issue in the moving machinery. As it stands, maintenance-free panels are a huge advantage.
Efficiency 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.
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. 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.
> 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.
> 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.
> 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.
I 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.
> 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.
By "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.
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.
Well, 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).
I 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.
Aren'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?
Insolight 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.
Cheap 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.
Isn'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.
If 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.
The 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.
I 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.
The 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.
This 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.
Well, I certainly hope you are right and I'm wrong. Still, the devil will be in the details and even with expired patents multi-junction cells are simply more expensive to produce. Keep in mind they only have to be ~24% more expensive to make to wipe out any efficiency gains and that's not a whole lot of margin. If this succeeds you might see a fraction of that passed on to the consumer and the cost of the bare panels long ago ceased to be the dominant factor in a regular (domestic) installation.
For large areas it might work out to be beneficiary earlier.
Heterojunction cells are an approach to reducing recombination losses near contacts in single junction silicon cells. Sanyo (now Panasonic) developed them in the 1990s and has shipped gigawatts of them. It's the same Panasonic cell technology that SolarCity (now Tesla) is expected to use in their New York factory. The vanilla heterojunction cell design is actually one of the simplest high-efficiency cells in terms of process flow. The main drawbacks are patents (until recently) and the limited heat tolerance of a-Si layers; standard screen printed silver metallization, fired at high temperatures, does not work for these cells.
I spent some time reading that, thank you very much for the pointers. Looks like you are right and this is in fact something that might just happen. Here's to hoping that it does.
For reference, in 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%.
That 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.
Zooming 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?
"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."
No - 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.
This 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?
I 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.
