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Solar Windows Could Help Power Buildings
Lucas123 writes: Several companies are now beginning to roll out translucent photovoltaic films or solar cells embedded in windows that can supplement a significant amount of energy in the buildings where they're used. SolarWindow Technologies, for example, is preparing to launch a transparent product made with organic PVs, while another company, Solaria, is cutting solar cells into thin strips and embedding them in windows. Both companies admit their products can't produce the 20% efficiency ratings of today's best rooftop solar panels, but they say that's not their objective. Instead, the companies are looking to take advantage of millions of skyscraper windows that today are simply unused real estate for renewable energy. One company is aiming at supplementing 20% to 30% of a skyscrapers power requirements. Meanwhile, universities are also jumping into the solar window arena. Oxford University has spun off a PV window company that produces semi-transparent solar cells made of semi-transparent perovskite oxide that has achieved a 20% solar energy efficiency.
You're also no mathematician
Why not add a sixth for 120% efficiency /s
I know that you're joking, but I'm going to analyse your post anyway ;)
These are said to have barely over 20% efficiency at the moment. I can't find where it says how much light they block, so I'm just going to pull a number from thin air and say 50%. This means that your first layer works at 20% efficiency and functions as a window; the second layer will result in 30% efficiency and be a bit too dark to be a good window (and cost twice as much too); 3 layers would be 35% efficient, triple the price, and basically unusable as windows; 5 would be 38.65% efficient, ludicrously expensive, and usable only on a tiny patch on the roof when the whole point was to sacrifice some efficiency in order to be able to use the surface area on the side of the buildings.
But I like your way of thinking , especially since it raises the question of what would happen if you go past 5 layers and start generating energy from nowhere :)
One m^2 of direct sunlight provides ~1000 watts, but due to the way things are, even the best solar panels can't get you more than, say 300 watts from that original 1000. Limits due to Carnot cycle apply.
That was the turning point of my life--I went from negative zero to positive zero.
Wait now... this dude is on to something. What would happen if they combined SIX layers?!
*mind BLOWN*
Remember that light energy can't be converted to electricity and also transmitted through the window; whatever percentage gets converted to electricity must be subtracted from the percentage that is transmitted. A window that converts 100% of solar energy to electricity would transmit 0% of the light; i.e. it would be opaque.
Cities don't have anywhere near the solar density necessary to make a dent in their consumption. There's just barely enough in a neighborhood, but when you get to multi-story density, it's a hopeless gesture.
It gets even worse when you use thin-films which have waaaay less efficiency than crystalline panels.
And it gets even worse when you mount them on vertical surfaces like skyscraper windows.
And it gets even worse when you have thousands of distributed pieces of small electronics that all must be maintained, managed and the energy combined.
I loooove solar and I can tell you it's just NOT WORTH IT. Make a big field outside the city and send the power in. Everything is a waste of time or just for show.
A lot of people have emotional feelings like, "but it's all just going to waste in the city." But use your head: It's all just going to waste out in the desert too. So be wise and put efficient, dense PV where there's lots of sun. Don't put inefficient PV distributed around where there's weak sun.
It's like trying to write a letter with twenty light pencils. Just use one dark pencil.
"100% efficiency" per window?
Yes, but then we don't call them windows any more.
More than 5 layers would be unsafe, since the windows would then be operating at 120% efficiency and arcing sweet, free electricity all over the place.
Eloi are stupid, throw morlocks at them!
Just so long as it doesn't arc onto my lawn.
Suborbital [spaceflight] is the special olympics of spaceflight. - Rei
As the article noted, the double benefit of this system is not just the token energy it generates but the ability to better control HVAC costs by reducing the amount of heat that goes in through the windows, reducing demands on air conditioning in the summer. That being said, based on the pictures, this system is not pretty: the lines running through the translucent cells are rather annoying to look at and could be shot down by builders for the aesthetics alone. It would be better if they could deploy this as some sort of window shade that can be retracted to allow for unobstructed views (looking at the photos of the sample setup, it reminds me of the translucent shades used in a lot of newer offices), but I don't think this technology is there.
thats_the_joke.jpg
Do not look into laser with remaining eye.
Carnot cycle refers to the efficiency limits of thermal generation or heat engines, ie a steam generator on a coal fired power plant or the efficiency of an internal combustion engine. PV panels do NOT operate on thermal generation and the Carnot cycle doesn't even apply. Other than that the rest of what you said was wrong.
Or we could stop designing our buildings to look like they're made out of glass...
Do not look into laser with remaining eye.
Actually, 5 layers would be absorbing 67% energy (assuming the layers are 20% efficient for all levels of intensity/frequency of light).
1 - 0.8*0.8*0.8*0.8*0.8 = 0.67
The article talks about changing all the south facing windows in the office towers. It sounds great but in the city there's usually another tall building across the street blocking the sun so there's not much point in changing all of the windows. Maybe the ones near the top that does get the sun. I could see it being of more use in less dense areas but not in city centers.
These films are so poor on performance, you can put 3-4 real solar panels on the roof and make the same energy.
This may be true for the time being, but solar window efficiency will likely be improved over time. Plus they're not likely to be covered by snow. Plus that's a lot of available surface area, and a lot of redundancy, to take advantage of. Plus it may be possible to use the power they generate close to the source of that power, reducing resistive power loss and, potentially, conversion loss.
They would not block sunlight from entering the building.
FTA, (and from the sub-heading no less): "Not only do solar windows produce power, but some reduce heat". So yes, they can reduce heat load. Admittedly, this would be a disadvantage in Winter - OTOH, it tends to be cheaper to heat a building than to cool it.
We are not lacking good solar panels for roofs. We are lacking utilities that will let us connect to the grid our parents paid for years ago.
The 'big grid' idea is about a century old. Except as a supplier to heavy industry, (and possibly as a backup to local power generation - now there's a switch!), it needs to be retired. As far as possible we should generate and store power locally, using micro-grids as necessary for purposes of redundancy. Such an approach would be more efficient, *much* more resilient, and greener - not to mention that it would make electrical utilities and their parasitic ways all but obsolete.
'The Economy' is a giant Ponzi scheme whose most pitiable suckers are the youngest among us and the yet-unborn.
Nope, GP is correct. most of the energy turns into heat.
Moderating "-1, Disagree" is simple censorship. Have the guts to post your opinion. -- Spazmania (174582)
Allowing less heat in would be good for the summer but bad for the winter. For that, I think the windows lined with e-ink would help. The windows can be set to darken during the day in the summer and clear during the day for the winter. In the winter, when you want privacy, there's a capability to scatter the light coming through to blur the view without blocking a significant amount of the light from getting in. These windows would look nice and they could eliminate the need for blinds or curtains. Set the windows to automatically open up when someone is home and the outside temperature is within a comfortable range (and it's not raining or too windy) and you'd have a significantly more efficient home.
Linux would use solar panels. The problem is where most pinguins live there isn't much sunlight.
Moderating "-1, Disagree" is simple censorship. Have the guts to post your opinion. -- Spazmania (174582)
Better read chapter 2 of your "Cliff notes"
That was the turning point of my life--I went from negative zero to positive zero.
Yes, but then we don't call them windows any more.
Yeah, but they would be great to *really* cool the room down.
SJW's don't eliminate discrimination. They just expropriate it for themselves.
As if they don't already routinely apply much cheaper coatings specifically designed to do that.
Not everyone likes living in a basement...
Faster! Faster! Faster would be better!
The extra power could go towards lighting the now-dark offices!
Maybe we could remove all skeumorphism, transparency, bevels, borders, and gradients here in the real world as well? I propose we call this style "new metro!"
Irony: Agile development has too much intertia to be abandoned now.
Far more helpful would be to add awnings over windows like the Petronas towers have. The view is not obstructed, but high angle sun is largely never hitting the windows.
PV does not work like that.
A single layer will absorb and transform most of the photons of a specific wavelength (a small band) into electricity (movement of electrons).
On the second layer, basically all of the photons mentioned above are already gone.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Limits due to Carnot cycle apply.
That is nonsense.
The Carnot Cycle is a principle of thermodynamic engines/systems. Which does not apply to a PV system.
Here we have a "photo electric effect" (guess who got a Nobel Prize for it?): https://en.wikipedia.org/wiki/...
The fact that our day PV panels have a "low" efficiency, comes from the fact that they only can react on/capture photons in a small bandwidth.
That has nothing to do with thermodynamics or Carnot, who -btw - as far as I know did not win a Nobel Prize.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
That is wrong.
On Average the amount of sunlight at the south pole is the same as at your place.
You forget they have close to three month eternal day and another 6 month something like a 50% day and 50% night cycle and obviously another three month more or less eternal night.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Why not add a sixth for 120% efficiency /s
Actually you can do that with just 5. You need to flip the two inside layers around and they can convert the light from the florescent ceiling lights.
"100% efficiency" per window?
Yes, but then we don't call them windows any more.
And that's why basement-dwelling übergeeks use Linux.
Escher was the first MC and Giger invented the HR department.
I think the English spelling is "penguin". Nevertheless, I named one of my machines "vin" so I can "ping vin" in the language of Linus.
Escher was the first MC and Giger invented the HR department.
Would you like to be able to see out those windows, or would you like them to be black?
You still have to pay to have them applied.
if it's done at the factory on automated machinery the cost is probably pretty minimal
no doubt as an anonymous coward you will get many well thought out answers to your question
> Remember that light energy can't be converted to electricity and also
> transmitted through the window; whatever percentage gets converted
> to electricity must be subtracted from the percentage that is transmitted.
A hot summer day...
* incoming sunlight reduced; check
* some electrical power provided for air conditioning; check
Now that's what I call win-win.
I'm not repeating myself
I'm an X window user; I'm an ex-Windows user
And then watch Dave Jones rant on a whole series of videos on how it just don't work as nearly as well as the KS page claims.
I know what you mean... I remember reading headlines about this as far back as 2002...When is it ever going to actually happen?
Solar panels are not heat engines, so Carnot cycles are irrelevant. The best cells have now reached 46% in the lab ( http://www.nrel.gov/ncpv/image... ). The high efficiency cells use multiple types of semiconductor stacked up. Each type is optimized for a different wavelength. Note that cell is not the same as panel, because less than 100% of the panel area is cells. Multi-layered cells currently are used on spacecraft and in concentrator modules, because they cost more than single-layer cells to produce. The efficiency gain only makes sense for those applications.