Holographic Solar Collectors

An anonymous reader writes "The MIT Technology Review is reporting that Prism Solar Technologies has developed a technique to use holograms to concentrate light onto photovoltaic (PV) cells. While the implementation is only about a 10x increase over PV cells without collectors such as mirrors/lenses (mirror/lens approaches can do 100-1000x), it is a great deal simpler, more compact, and cheaper. Also because of the concentration, there is less need for physical PV cell real estate compared to crystalline PV silicon cells of similar output."

Comments

Only 10x? That's huge!

[chriss]

10x increase for the holographic cell may sound bad compared to 100x-1000x for mirrors/lens. But in the installations I know that use mirrors or lenses they take up most of the area. If 10% of the whole surface was PV cells and 90% were e.g.. mirrors (a very conservative assumption, I think the PV cells will cover less then 1%) you would gain an effective increase of 100x instead of 10x. (This is not entirely true, since these new PV cells are only part energy creating silicon, most of their surface is just the holographic lense. But still a massive space saver compared to classical mirrors.)

Plus you will usually have to place mirrors on the ground due to their weight and the weight of the motors attached to them to make them follow the sun. In contrast you can place PV cells on almost any surface, although you will loose a lot of efficiency if you can not orient them towards the sun.

If you completely ignore that there are theoretically more efficient methods of concentrating the energy onto PC cells, you still get a 10x improvement over the typical installation (on a roof, with no fancy mirrors at all). And then 10x is huge.

Re:Only 10x? That's huge!

[Anonymous Coward]

I am a complete solar energy newb, but I was a physics major. It sounds to me that the benefit of this technology for ordinary "on the roof of my house" installations would not be to increase the amount of electricity an installation could provide, but rather to make it cheaper by only having to use ten percent the amount of PV cells in the same area of solar panel. In a square yard of solar panel, you only get X quantity of solar radiation... a one square yard panel of naked PV cells shouldn't get any more energy than one square yard with holographic cells... right? Or do these acutally focus rays, at angles that would not have impacted the PV surfaces, onto them?

Please comment.

Re:Only 10x? That's huge!

[chriss]

As far as I understand it, it will not increase the maximal amount of energy you could produce on your roof. Actually, this would decrease. If you pack regular PV cells on your whole roof, this would generate the most energy. But at the highest cost.

Most installations do not cover the whole roof, only parts. With these new cells integrated in holographic lenses you can actually cover more of the roof area for almost the same price. And although the area of active silicon will not increase, the lenses will concentrate the solar energy from the increased area onto the silicon resulting in a higher energy production.

Re:Only 10x? That's huge!

[Anonymous Coward]

loose is the opposite of tight.

lose is the opposite of find

Re:Only 10x? That's huge!

[Ungrounded Lightning]

It sounds [like the improvement is] to make it cheaper by only having to use ten percent the amount of PV cells in the same area of solar panel.

Yep.

a one square yard panel of naked PV cells shouldn't get any more energy than one square yard with holographic cells... right?

A square yard of naked cells (or cells imbedded in a classic panel), a square yard of focusing concentrator onto a smaller area of cells, and a square yard of holographic panel containing some smaller area of cells, would all potentially collect the same power (neglecting concentrator inefficiencies).

The point is that:
  - doing a square yard of collection with a square yard of cells costs.
  - A normal focusing concentrator focuses not just the useful light, but the non-useful far-infrared, so you need serious cooling of the cells to run at a high degree of contentration, and the concentrator is bulky, heavy, and may need to track the sun.
  - This thing is WAY cheap to make, doesn't focus useless infrared below the cells' bandgap frequency, and doesn't need to track. It loses some of the light, so you may need a little extra area to make up for that. But you use only 10% of the cells compared to a classic panel for a given amount of power.

As I read the drawings this is basically a glass plate with solar cells glued to 10% or so of the back and the remainder covered with a holographic coating.

The holographic coating diffracts the desired frequencies so they become trapped between the faces of the glass plate by total internal reflection (as light is trapped in a fiber optic light pipe) and it bounces back and forth between the surfaces until it hits a place where a cell is glued to the back. At that point the glue's index of refraction is high enough that the light can escape into the cell. So you just need enough cells that most of the light encounters one before it gets to an edge or leaks out where a dirt speck sits on the glass. (I'm not clear how they keep the holographic coating from diffracting it back out toward the sun but I presume they've got that covered.)

Far infrared doesn't bend enough to get trapped so it escapes out the front or back of the panel.

This is VERY nice. With maybe 90% of the infrared passing through the panel or bouncing out the front of it you don't get the massive greenhouse effect of a classic panel.

Re:Only 10x? That's huge!

[Anonymous Coward]

although you will loose a lot of efficiency Careful!

Re:Only 10x? That's huge!

[skids]

Actually there are some cells (the triple junction mono-Si and for that matter thermophotovoltaics) that have higher efficiencies (in the 30% range) the more light you throw at them. You do still have to keep them cool, but it's been found that passive cooling is sufficient for a good number of systems -- I think some even over 10 suns. This system likely doesn't use the triple junction cells because you have to get into the 30-100 sun range to realize the improvement, and they are expensive.

There are a lot of concentrator systems due to hit the market in the next year or two -- here's my current list: http://www.dailykos.com/storyonly/2006/3/7/114711/ 9242

This system will probably have a lower Wp/m3 than a regular panel, however price counts for a lot and many people have more roof, or yard for that matter, than they need so systems like this have an appeal. However since they are for the most part even pickier about incident angle they are mainly going to be of interest in areas that don't get too much cloud cover. There are some omnidirectional reflector arrangements but they aren't flat profile -- clouded areas will probably be looking at more tolerant thin films, which are also pretty poor in the Wp/m3 department.

The big question at this point is whether there will be a reduced-silcon undercutter on the market soon or whether companies will bid in at the going rate in order to monetize and pour that into more manufacturing facilities. I guess we'll see the first test of that when the EverGreen Spruce string ribbon panels get to the retailers.

No space savings

[Anonymous Coward]

they just replace sections of PV cells with this hologram stuff-- the panel is the same size, just less silicon

Re:No space savings

[Anonymous Coward]

There is a lot of loss in collection using this holographic method. So actually, if you want the same power output, it will require more area, possibly a lot more.

Sounds like a ST:TNG episode...

[Hee-Man]

Just becareful about programming these into the holodeck. The last time that happened, the Enterprise was almost fried!

Re:Sounds like a ST:TNG episode...

[cnettel]

Just when Riker flirts with the inventor's wife.

Re:Sounds like a ST:TNG episode...

[Anonymous Coward]

Ack, two seconds after I saw the comment I remembered that episode. I think I need to go kill off some brain cells.

Holograms?

[exp(pi*sqrt(163))]

These sound like good old fashioned diffraction gratings to me. 'Hologram' sounds like nothing more than a marketing term. One disadvantage of using diffraction gratings is that the amount of bending is wavelength dependent. And it seems like the marketing department managed to put a spin on that too.

Re:Holograms?

[chriss]

Since you can create multiple refractions inside a hologram, you can create a much better lense than with diffraction gratings. So while both are basically flat lenses, the holographic version is much more efficient.

Re:Holograms?

[thePig]

And it seems like the marketing department managed to put a spin on that too
Not sure whether that is a spin. Heating is a real problem for Solar concentrators.. A lens will concentrate light, but also IR. These are quite high temperatures we are talking about. If they can actually take out IR from the question, then this indeed is a good idea..
Also, I can see pratical applications on window sills etc. In our place, temp can go up to 110. Think of a cheap window which will let in only light (similar to the current double pane windows)...
It has future.

Re:Holograms?

[c_fel]

From the article :
Holograms have advantages that make up for their relatively weak concentration power. They can select certain frequencies and focus them on solar cells that work best at those frequencies, converting the maximum possible light into electricity.

At first I found this sentence a bit funny, cause I didn't see why we should select a wavelength instead of capting all of them. You answered my question : since we can't concentrate all wavelenghts, we optimize things for the best one.

But we have to agree that is a tricky way to talk about a problem...

Re:Holograms?

[tsotha]

One disadvantage of using diffraction gratings is that the amount of bending is wavelength dependent.

One man's disadvantage is another man's cooling system. Since the solar cells are also wavelength dependent, the goal is to collect all the usefull light and let the rest (mostly) pass harmlessly through the glass plate. Very clever.

Solar collecting is good.

[crazyjeremy]

When you can concentrate the suns energy the collector is more efficient. This is a VERY good thing, especially considering the amount of cloudy / rainy days most places have. Lots of people do not go solar because it simply does not draw enough power for the amount of money they have to use to build the system.

Re:Solar collecting is good.

[shmlco]

"Lots of people do not go solar because it simply does not draw enough power for the amount of money they have to use to build the system."

I can see solar as a potential option for some businesses, but for home use you still have the small problem of no power output during the night. And that's usually just when you want some lights, television, heat, and so forth.

If they want solar to REALLY catch on someone is going to need to develop not just a cost-effective solar cell, but also a cost-effective way to store and reuse the energy collected during the day.

Re:Solar collecting is good.

[Glonoinha]

If only there was a way to store all that electric power. Maybe massive plates of lead and zinc in a acid solution, in big heavy square things with little plugs on top to add distilled water from time to time (I have no idea why, but I envision that there would be a good reason to do so on my mythical device.) Give it a catchy name like 'Deep Cycle Truck Battery' and sell them at Wal*Mart for ~$50 apiece, letting us fill an entire room with them for under a thousand dollars.

Someone should invent that.

Re:Solar collecting is good.

[networkBoy]

Since plain ol solar will never meet our energy needs, just use the grid as a storage device. Durring the day the grid is fed by solar energy with the shortfall made up of anything else available, at night the total demand for energy is lower so those same reserve sources can feed the grid. If there ever is a time that our entire grid can be solar (I doubt highly that this will ever happen) then you can charge a kinetic sourcew against a gravity well* or charge a massive flywheel with the excess power.
-nB

* for example pump water up a mountain to a storage lake and let it run down durring the night for power
-nB

Re:Solar collecting is good.

[Gyga]

Most enviromentalist don't advocate pure solar, they advocate using it the take strain off other systems, I look at AC in the desert as big strain to be removed.

Put a solar farm on several people's roofs, put a wind farm here and there, coastal cities get wave generators, and everything else can be nuclear. That is the future, not pure solar.

If this new system could be inmproved to focus the light to a small line I wonder if panels could be hid inbetween roof shingles? Removing the ugly factor entirly, though thick black lines could be cool.

Re:Solar collecting is good.

[pellis23]

That's what grid-connected solar arrays are for. You use the grid as your battery. In California at least, with a grid-connected array, PG&E buys any surplus electricity you generate during the day (while you're at work and the sun is shining) for the more expensive daytime retail price and when youg et home and actually consume, you buy back from the grid for the cheaper, night time price.

Re:Solar collecting is good.

[networkBoy]

Just for the record, those batteries _suck_ for solar energy collection.
Something more like this:
http://www.ibsa.com/estore/search.asp?details=1&ms cssid=KS9FNAJCUXGV9LBH81QUWL707VKN9LB0&Ntt=mining& N=0&Dx=mode+matchallany&part_number=4D-XHD&Nty=0&D =mining&Nu=Part+Number&Ntx=mode+matchallany&part_d esc=Workaholic+-+1000+CCA&Ns=product+Type%7C0%7C%7 CRank%7C1&Ntk=SearchGroup
Though that's with an ultra quick search.
-nB

Re:Solar collecting is good.

[crazyjeremy]

If you

* for example pump water up a mountain to a storage lake and let it run down durring the night for power -nB

It takes more to pump it up than what you get back from it coming down. Basic physics.

Re:Solar collecting is good.

[topham]

Yes, but you can let the water out at night and still have power...

Dams are really large storage cells. (Batteries)

Re:Solar collecting is good.

[grqb]

Solar power HAS really cought on in some parts of the world though...like Germany. Germans can sell solar power back to the grid and actually make a profit. A lot of people are renting out the roofs of some farms just to put solar cells on it and feed it back to the grid. In a way Germany is subsidizing the solar industry for the rest of the world (at least until the refined silicon shortage is solved) because they are driving the industry right now.

Re:Solar collecting is good.

[mugnyte]

  I agree, except you missed one major change in the energy usage: population decline. The rate of change from efficiency based on fossil to other sources may be too high. So, the populate is affected through a massive price shift for most goods and transportation. I believe most folks will eventually conclude that energy resources can only come up so far, the rest is bringing down need to match.

There's only so much "getting off the [old] grid" one can do, and when? Most folks agree that "not now" is the safe bet, but like trading I think the shift will be more emotionally triggered than anything else. We simply have to wait for the panic button to get pressed to see if any of this will make an impact, I fear.

Re:Solar collecting is good.

[Anonymous Coward]

thats a good link, can you read it back for me over the phone ?

Re:Solar collecting is good.

[crazyjeremy]

Very true... I didn't even think about that.

Truly, that could be a good backup plan to my initial instinct... Where possible, I think it's best to feed back into the grid... (some states require electric company to reimburse you). Then at night, what you use gets deducted again... By the end of the month you usually use a fraction of the electricity a normal home would have.

Re:Solar collecting is good.

[Jeremi]

If they want solar to REALLY catch on someone is going to need to develop not just a cost-effective solar cell, but also a cost-effective way to store and reuse the energy collected during the day.

In developed areas, at least, there is already an easy way to do that: use the power grid as your energy store, by selling power to the grid during the day and buying it back again at night.

Re:Solar collecting is good.

[networkBoy]

"Where possible, I think it's best to feed back into the grid..."

So do I, which is whi I led off with this statement:
"Since plain ol solar will never meet our energy needs, just use the grid as a storage device. "

The point of charging the "gravity battery" was that should we really have an absurd ammount of solar power available, that we can feed the entire country's needs durring daylight hours, then storing the excess would not need to be that efficent, we'd be so far ahead of the game just by turning off the power plants durring the day.
-nB

Re:Solar collecting is good.

[networkBoy]

"thats a good link, can you read it back for me over the phone ?"
Sure:
ache tee tee pee colon whack whack dub dub dub aw fuckit dot see oh em

Re:Solar collecting is good.

[crazyjeremy]

I have the perfect location for something like this... But I would want to see how much energy it would really take to make it work...

Have you ever seen http://www.homepower.com/ magazine?

Re:Solar collecting is good.

[shmlco]

"You use the grid as your battery."

But it's not a battery. Yes, you may be able to sell some excess power to the "grid", but the "grid" doesn't store energy, it just distributes it. As such, a power station connected to the grid still needs to be able to supply ALL of the energy everyone needs at night.

So at night solar has issues. In fact, it's not too great on cloudy, snowy, short winter days either.

Re:Solar collecting is good.

[drinkypoo]

Not sure what pump efficiency is like, but pelton wheels can be very efficient, well over 80%. And if you have enough flowing water available, you can use the water to pump the water uphill using an arrangement of cylinders and valves - and nothing else. Then you can let it out at night in order to generate power when the solar's not working.

Re:Solar collecting is good.

[TheRaven64]

There is a 'power station' not far from me which monitors demand on the grid. When there is a low demand, the price of electricity goes down[1] and the buy it. They use this electricity to pump water up a hill from one reservoir to another. When the demand goes up, so does the price of electricity. They open a valve and let the water through some turbines, generating electricity which they sell back to the grid.

It takes a few hours (at least) for most power stations to significantly alter their output - and over a day to completely turn one on/off. When other power stations are overproducing, they provide somewhere for the spare energy to be stored. When others are underproducing, they take up the slack.

While the grid might not be a battery, it certainly contains some fairly large ones. Even if it didn't, being able to turn off a fossil fuel power station or two[2] during the day would be a significant environmental benefit.

[1] While you, as an end customer, may only see a flat rate (or maybe a peak/off-peak rate) for electricity, your supplier sees a significant variation in prices from minute to minute and from power station to power station.
[2] Of course, you would not actually turn one off, but you might reduce the load (and hence fossil fuel usage) on 10 by 10%.

Re:Solar collecting is good.

[martinde]

> If they want solar to REALLY catch on someone is going to need to develop not just a cost-effective solar cell, but also a
> cost-effective way to store and reuse the energy collected during the day.

Agreed. Flywheels seem like a nice solution to that problem. Of course, next thing we'll know they'll be writing about "torque pollution" ;-)

Re:Solar collecting is good.

[shmlco]

"for example pump water up a mountain to a storage lake and let it run down durring the night for power"

Okay... just for what it's worth, have you ever been to the Hover Dam? Ever seen the amount of water that goes through the turbines each day? Assuming, or course, you're not in Kansas or Indiana or some place lacking in available mountains.

Or considered just how many flywheels you'd need, and how large they'd have to be, to power an entire city for a night.

Not saying your ideas aren't practical, but...

Re:Solar collecting is good.

[x2A]

nah you just join the roof-exchange program, where you put your solar cells on somebody's roof the other side of the planet (where it's light when it's dark for you), and they put theirs on yours. The most convenient option is to drag a cable from them to you (through the earth is the shortest route), but if that's too expensive for you (with the electicity savings, it won't be for long) they simply send you the electicity by shipping batteries they've charged to you. Simplicity.

Re:Solar collecting is good.

[shmlco]

"While the grid might not be a battery, it certainly contains some fairly large ones."

The operative word in that sentence being "some". Given all of the electrical grids on the planet, it looks like about three-four dozen or so are pumped storage systems. I also liked the following quote: "In 2000 the United States had 19500 MWe capacity of pumped storage. This produced a net -5500 MWe of power because they consume more power filling their reservoirs than they generate by emptying them."

Re:Solar collecting is good.

[Anonymous Coward]

You need to physically go and see some houses that have "whole house" solar installations, talk to the people there. Sigh... I can yammer about it all day long, say I lived with it for years, that the battery banks (cheap normal flooded lead acid storage batteries) could go for four days with heavy clouds, that on sunny days the batteries would be fully chrged by 1 PM in the afternoon despite heavy usage, that the payback period is less than ten years, etc...it won't do any good. Not a damn bit of good, This is the same FUD from the 70's, probably based on "true science facts" from rush limbeau and the US electric monopoly company..

The tech is here, it works, and it's affordable tied into the 20 year note, and the tech usually has at least that long a warranty, 30 years is common now. A lot of folks are now getting less than a ten year payback because rates are so high for electricity, and do you really think electric rates will be going DOWN in the future?

There are THOUSANDS of installations in the US and millions world wide. It is not "theoretical" it really doesn't need any more "study", we are at the marginal improvements stages now, like with computers, roughly when they went over a couple gigahertz CPU speed. They got good enough and affordable enough at that point most anyone who wanted one could get one, now computers are common landfill trash..

This is not anything weird anymore, or "in the mysterious future", solar PV is mainstream proven robust technology. It WORKS and got cheap enough around ten years ago, even cheaper if you just do a meter spinning backwards grid tie with it. Which coincidently works when AC demand is the highest in the summer, "the heat of the day", the more nice hot sunny days, the more AC is needed, the more solar PV slaps the power into the grid or your batteries at the right time.So you have two basic ways to do it, store it (I recommend that, much nicer), or sell it back cheap. Either way it works now. And the US is falling behind places like germany,japan and china when it comes to the alternatives, because they *aren't stupid*. They can check out the news and see energy is rising in price a LOT faster than most anything else, oil has gone up around 25% in one year. Knock knock, hello, this is your wallet speaking. The other energy forms will be close behind, oil is always the base energy pricing indicator.

That's why japan, germany and china are in massive solar upgrades-along with wind and anything else they can do NOW, because they "get it" on looking past one fiscal quarter, and in the US-we mostly don't. Two days is a push here, this is the short attention span short bus to school nation, ipods and video games are the only thing important technologically speaking..these other nations can see the handwriting on the wall and are getting in hard, fast and early when it is still cheap. Also why they pump out a lot more engineers than we do, and why they actually reward "brains". We reward sports heroes, movie stars and corporate CEO thieves.

You are paying an electric bill anyway, tell me, when will that bill be PAID OFF? When do you get to "own" your electric production if all you have is the grid source? Oh, never? Is that so, so how is there any "payback" and how is it "affordable" if you never get to own it? If solar needs a payback, how about all other forms of sold electricity? When is your payback, what sort of deal did the local electric company give you? What is your "payback" time frame at your house with just relying on some company like enron? 50 years paying to RENT? Say you start at age 20 and pay an electric bill for 50 or 60 more years-what do you have to show for it after all that time?

NOTHING, you rented! Same as if you rented an apartment for 50 or 60 years instead of buying a house, no equity, nothing. It's *dumb*, retarded now that we have a variety of workable alternatives. What is your electric bill by the kilowatt hour in 5, 10 years, 15 years years? Oh, you don't kn

Re:Solar collecting is good.

[merchant_x]

You may find this interesting.

http://www.tva.gov/heritage/mountaintop/

Re:Solar collecting is good.

[Anonymous Coward]

That and more energy effeciant appliances. All major computer companies now have some sort of plan to decrease energy consumption (aimed at portable clients, but will help general usage). Greenhouse grown food (large tower greenhouses, layer after layer, after layer), locally will remove many transportation costs and fuel usage.

Re:Solar collecting is good.

[cridanb]

a pump storage facility which pumps water up a hill is operational in wales and connected to the national grid in the UK

it is used to balance out extreme loads reacting quickly to smooth out demand so that more power stations are not kept idling

Re:Solar collecting is good.

[rjstanford]

This produced a net -5500 MWe of power because they consume more power filling their reservoirs than they generate by emptying them.

Right, which is why they work as load-balancers and promote financial efficiency rather than actually promoting power efficiency. Thankfully the main generating systems have already tied financial efficiency to their, somewhat more fluctuating power efficiency, so it all works out.

Re:Solar collecting is good.

[Anonymous Coward]

I'm not entirely a solar enthusiast, but one thing that irks me about a lot of comments is that solar is not a good single source energy. Huh!? NO source is a good single source energy. Just like there's no point in driving an SUV around town (unless you make a point of running over people), there's no point in trying to drive a Lamborghini over a gravel backroad in the middle of nowhere.

Some energy sources are good for some areas and some purposes, and can/should be augmented with other energy sources.

That said, the biggest problem I see with just about any of these alternative energies produced at the site of a home, is that it takes a lot of space and expense to store the energy in batteries etc. Feeding it to the grid is OK probably in some areas, provided that there aren't TOO many homes generating power, and the portion of power plant generation isn't dependant on nuclear power. You can't just turn a nuclear power plant on and off with a simple switch (as I assume is true too to a lesser degree for an oil or coal plant), and you'll have a problem with power requirement prediction.

Just like there's no single source perfect energy so we need to keep developing all viable sources in parallel, I think there needs to be more development put into power conservation methods, and new storage methods. Most people don't want to part with the comfort of all the electrical appliances, and would actually prefer to run them longer and stronger if costs permitted. I know I do! Make them consume less electricity. For example, housing can be made more power efficient. It doesn't just have to be the electrical appliances that need more development to conserve power. And while it's not exactly an energy storage method, running an electrical boiler during the day (solar) or when winds are strong (wind turbine) and keeping that heat for later use in the bath, kitchen, and central heating is another idea. In the summer you could use it to freeze water into ice, and use it for the A/C at night. While I don't think it's viable NOW, using the excess power to split hydrogen and oxygen for later use in a fuel cell is another one. Anything wasted is bad, so if you're gonna waste it, it would be better to use it for something else even if the efficiency is really crappy. (But then of course there's the issue of installation cost, and production cost in energy terms of whatever instruments need to be used, and on and on and on I go....)

I guess I rant too much...

Re:Solar collecting is good.

[patio11]

Dubya Dubya Dubya dot tinyurl dot com slash M as in Mercury, G as in Green, B as in Blue, A as in Apple, N as in Nature.

Or, if you're not reading over the phone, just click the bloody link. TinyURL was MADE for that sort of monstrosity :)

Re:Solar collecting is good.

[Anonymous Coward]

Here is a link http://www.consumersenergy.com/content/hiermenugri d.aspx?id=31 to the pumped storage plant near my house. It's ridiculously huge, it holds 27 billion gallons of water -- the equivalent of 2 million backyard swimming pools. It supplies Detroit with power during the summer. It runs on an economic timescale, at night when power is cheap they fill the resivoir by running the turbines in reverse. Then during the day when power gets expensive, they open the gates and let the water flow past the turbines creating electricity. They only run it when the cost of pumping the water up into the resivoir exceeds doesn't exceed the profit gained by letting it all out. Surprisingly that happens about 360 days a year.

Re:Solar collecting is good.

[triffid_98]

Since plain ol solar will never meet our energy needs,..

I wouldn't say that. Point enough satellites with solar arrays at that freaky thing we call 'The Sun', and you've got tons of energy. The problem is finding a long enough extension cord...

Re:Solar collecting is good.

[shmlco]

As you this...

"The relatively low energy density of pumped storage systems requires either a very large body of water or a large variation in height. For example, 1000 kilograms of water (1 cubic meter) at the top of a 100 meter tower has a potential energy of about 0.272 kWh. The only way to store a significant amount of energy is by having a large body of water located on a hill relatively near, but as high as possible above, a second body of water. In some places this occurs naturally, in others one or both bodies of water have been man-made."

IOW, it's a technology that needs very specific circumstances and locations to be practical.

Re:Solar collecting is good.

[QMO]

"* for example pump water up a mountain to a storage lake and let it run down durring [sic] the night for power"

FYI: For those that think that this is just a random idea that networkBoy made up, http://www.nypa.gov/facilities/blengil.htm and http://www.nypa.gov/facilities/niagara.htm are examples of where this has been done for years.

Re:Solar collecting is good.

[hcpf]

Actually there is something better: Edison battery. Cheap, powerful, and heavy.

So many stories but where are they?

[Zaai]

Pardon me for being sceptical about the actual commercial feasability of this.

Over the last decade quite a few of these wonderful improvements have been announced yet the commercially available solar-cell still has an efficiency of less than 15% and the price hasn't changed that much either.

I wonder if these announcements are more motivated by an upcoming investment round...

God knows we could use them, but when do we get to see them?

Re:So many stories but where are they?

[crazyjeremy]

Products like this decrease the amount solar panels needed. Many of the wonderful improvements are available, but at a very high cost. This development specifically reduces the cost needed to attain the same amount of power.

Re:So many stories but where are they?

[Anonymous Coward]

I doubt this will make the panel any more efficient in that respect, it will just use a lot less silicon to get it's 15%.

Re:So many stories but where are they?

[Anonymous Coward]

Yes, efficiency has generally remained at around 15%. (Except for one company in California, which is commercially producing panels with 21% efficiency, but the competition remains stuck around 15%.)

Cost per watt is another matter however. The US Department of Energy (http://www1.eere.energy.gov/solar/mission_vision_ goals.html) reports a rather dramatic drop in the cost per Kilowatt-hour over 12 years from $0.40 in 1991 to $0.20 in 2003. I believe the price has spiked in the last couple of years due to very high demand at this price point. Demand is projected to outstrip supply for the next couple of years until new solar panel production facilities can be completed.

This development may help to further reduce costs by allowing the creation of solar panels which use fewer solar cells.

Link

[Anonymous Coward]

The technology

Re:Link

[Anonymous Coward]

The photos in this PDF presentation show some panels which, puzzlingly,
one can pretty much see right through in the non-silicon areas. Should
not the entire panel look substantially dark? As it is, the panels
cannot possibly be using the energy that apparently just sails right
through the gaps.

A great deal simpler, more compact, and cheaper...

[Anonymous Coward]

..and only 10x to 100x less effective than alternatives! Sign me up.

Alternative to each other?

[onion2k]

In their ability to concentrate light, holograms are not as powerful as conventional concentrators. They can multiply the amount of light falling on the cells only by as much as a factor of 10, whereas lens-based systems can increase light by a factor of 100, and some even up to 1,000.

What's stopping me using a holographic collector in conjunction with a mirror/lens affair? Use mirrors/lens' to angle 100 - 1000 times more light energy on to the hologram .. That, presumably, would get the cost down yet further because it'd need even less silicon.

Re:Alternative to each other?

[Phillup]

What's stopping me using a holographic collector in conjunction with a mirror/lens affair?

That would be innovative... and they have this thing designed to stop that kind of stuff.

It is called a 'patent'.

Re:Alternative to each other?

[TallMatt]

I like your idea, and I think that would increase the output even further. However, the problem with mirrors and lenses is that they are heavey, and take up a lot of space, which in the end, might not save much cost.

Re:Alternative to each other?

[Spy der Mann]

What's stopping me using a holographic collector in conjunction with a mirror/lens affair?

Why use a mirror lens when you can replace it with ANOTHER holographic collector?

Re:Alternative to each other?

[Marksolo]

The problem with concentrating the light too much is it generates more heat. Like a computer heat causes problems it reduces the efficency of the solar cell. Also the heat increases the rate the cell degrades and will have to be replaced more oftain. 10x is a reasonable amount of concentration because it does not significantly reduce efficency and does not stress the chip.

Re:Alternative to each other?

[demonic-halo]

The issue here is the holograms are a replacing the mirrors/lenses. The actual photo cells are still the same.

The idea here is the holograms could be made flat while mirrors you'll have to link up with motors to track the sun.

If you have mirrors already tracking the sun, then you don't need holograms to redirect the light to the photo cells.

Re:Alternative to each other?

[Anonymous Coward]

Concentration is highly overrated from a cost standpoint. A typical solar cell runs about $3/peak watt produced at 1 sun illumination. A 10 to 1 concentration ratio would reduce solar cell area to $0.30 if you could continue to use the same cell and it can handle the concentration. You have achieved 90% of the possible cost reduction for the solar cell. A 1000 to 1 concentration ratio only buys about you another 29.9 cents or so cost reduction of the cells and you have to pay for a much more complicated concentrator setup.

OK, it's not quite that simple. What actually happens is that to design cells that can make use of a 10 to 1 concentration ratio may cost a little more than a standard cell. And today, these are a somewhat special product, so lack of an economy of scale further increase the cost compared to the standard cell. Cells designed for a 100 to 1 or a 1000 to 1 concentration ratio are an extremely specialized product and cost a mint, although you need very little total area of the cells themselves. The balance of the concentrator becomes a key cost in the system.

The other thing that happens is that when you are going for a high concentration ratio, some of the cells inherently get more efficient (as long as you can keep them cool... more of the "other costs" to deal with). In addition, because you are using just a little bit of specialized solar cell, you can pay a bit more for fancy triple junction cells that are more efficient by as much as a factor of two (up to say 30% efficiency at converting light to electricity compared to the standard silicon cell). However, the losses in the optics and the need for active cooling will take their toll on the system efficiency.

What it all seems to boil down to is that you have to design and cost out the system as a whole before you can say what makes sense for the market.

Re:Alternative to each other?

[LunaticTippy]

TFA states that the hologram selectively routes heat away from the cell.

Comment removed

[account_deleted]

Comment removed based on user account deletion

Hologram, eh?

[LochNess]

Finally, a use for Arnold J. Rimmer.

Re:Hologram, eh?

[dubbreak]

Finally, a use for Arnold J. Rimmer.

If you didn't find that absolutely hilarious you really need to watch some Red Dwarf.

Re:Hologram, eh?

[Tumbleweed]

Finally, a use for Arnold J. Rimmer.

Rimmer Directive 271 states clearly, "No chance, you metal bastard."

Re:Hologram, eh?

[Mr. Flibble]

Your comment about Mr. Rimmer makes me very angry, I know what I should do with you, but who would clean up the mess?

-- Mr. Flibble

Promising...

[dakirw]

Anything that can provide decent solar generation more cheaply would be good. Sounds like their process improvements in the 2nd gen panels might meet the $1.50/watt figure mentioned in the article. In any case, costs of any solar tech will need to go down quite a bit to support more widespread use, especially in developing countries.

Re:Promising...

[Jeremi]

In any case, costs of any solar tech will need to go down quite a bit to support more widespread use, especially in developing countries.

The other possibility is that the price of the alternatives might go up. If that happens, then solar will look more attractive even at its current pricing.

What happend to that South African break through?

[Lokni]

Or was all of that just a bunch of BS?

10x input != 10x output

[EmbeddedJanitor]

Silicon solar cells are still too damn expensive and power hungry to manufacture to be a useful mainstream generation tool. The only places they're really being used is where mainstream supply is not available/practical or where they are heavily subsidised for political/marketing ends. Increasing concentration to reduce the silicon are does reduce the amount of silicon and therefore potentially reduces the $ per W. However...

PV efficiency reduces significantly with increase in temperature (which is why you see solar racer folk pouring water on the PV panels). Thus just cranking up the sunlight by concentration does not give a linear increase in output. PV cells for concentration thus need to be made thicker and differently (to code with the extra current, heat sinking etc.) but hopefully the payback is still there.

Personally I think the PV quest is being approached incorrectly. There's too much emphasis on efficiency. Labs try to out % eachother and the big solar showcase is the solar race which is all about high efficiency cells.

What they should target is $ per Watt because that is the real hurdle to making PV viable. Who cares if it's only 5% efficient, so long as it is cheap? Tile your house with the stuff to get the area.

Re:10x input != 10x output

[trixillion]

From the article it is clear that this technology is specifically designed to address two of your concerns. Admittedly it helps to have a background in physics in order to understand some of the concepts (particularly the optics.) Firstly, the holographic lens and waveguide have been designed to direct certain ranges of wavelengths to the silicon and the other wavelengths away from it. This helps to prevent overheating of the silicon cells. Secondly, the lens system is there in order to collect more light per area of silicon used. This causes the $/Watt to increase, while the efficiency (Watts converted per Watt theoretically availlable) remains the same (well, in a perfect world, it sounds like this will work significantly better in their second generation.)

Re:10x input != 10x output

[syphax]

Who cares if it's only 5% efficient, so long as it is cheap? Tile your house with the stuff to get the area.

You are almost absolutely correct. Except for two things:

1. Low efficiency leads to higher indirect costs- specifically, the infrastructure that holds the cells and connects them to the grid. As you get down to lower efficiencies, these costs become significant.

2. Even at 10% efficiency, you need a huge area to produce a significant amount of juice. Sure, we could in theory generate all the energy we need in the U.S. by covering "only" around 1% of the U.S. land area with 10% efficiency PV (practical issues aside), but that still works out to be a huge area. Like, say, Maine. So even if we had a nice, cheap, low-efficiency solar technology, it's usefulness would ultimately be limited by land use constraints.

Re:10x input != 10x output

[Anonymous Coward]

"Thus just cranking up the sunlight by concentration does not give a linear increase in output. PV cells for concentration thus need to be made thicker and differently (to code with the extra current, heat sinking etc.) but hopefully the payback is still there."

you didn't actually RTFA did you? of course not, where did I think I was....

Re:10x input != 10x output

[Anarchitect_in_oz]

Given that in most places we want power we also want hot water.
I'm not sure why they don't combine PV Solar with absorption panels linked to a heat pump and the hot water system, or heat the pool.

Finding uses for heat, in most building isn't all that hard.

Deal with PV's problems by teaming with other technologies instead of trying to solve all the problems in isolation.

Re:10x input != 10x output

[rolfwind]

2. Even at 10% efficiency, you need a huge area to produce a significant amount of juice. Sure, we could in theory generate all the energy we need in the U.S. by covering "only" around 1% of the U.S. land area with 10% efficiency PV (practical issues aside), but that still works out to be a huge area. Like, say, Maine. So even if we had a nice, cheap, low-efficiency solar technology, it's usefulness would ultimately be limited by land use constraints.

I'm sure the black tar roofs (houses) or flat commercial roofs in this country take quite a bit of area up, without being too useful... maybe we can put something on top of them. Of course, solar panels are to be put on after the more efficient evacuated tubes are on, but still:)

Re:10x input != 10x output

[raygundan]

Sure, it would take an area the size of Maine, but how much land is already covered by one of the following?

1. Rooftops
2. Parking lots
3. Paved roads

I'd wager it's close to the area you need, and covering any of the above with solar panels would have little to no effect on anything, since the roads/roofs/lots are already nicely free of plant life that might want to use the sun.

No reason not to stick a little 400w wind turbine on every other streetlight pole, either.

The big limit is financial, and this solar development helps in a big way.

Re:10x input != 10x output

[syphax]

Rooftops

Substantial. People have actually looked at this, but I don't have the numbers at my fingertips. It's a big number, but I think that when you filter out for the ones that could realistically have panels on 'em, it is only a pretty big number.

Parking Lots

This is my personal favorite. However, you'd need to build the infrastructure to hold the panels off the ground, which adds not insignificant costs. So in this case, efficiency is a strong driver of overall costs.

Paved roads

There are lots of practical constraints here, but in some contexts it could make sense.

Re:10x input != 10x output

[sgt scrub]

(1(kW/(M^2))*.1)=100W/m^2

100 Mile X 100 Mile Panel group, placed in the Majave desert, would generate enough energy to meet the electricity needs of the U.S.

Re:10x input != 10x output

[maxume]

Texas, New Mexico and Arizona are all big and sunny. There are many Maine's worth of land available there.

Re:10x input != 10x output

[raygundan]

I agree with all of that. Parking lots could start small-- there is often an in-place array of streetlights, which could support a few square yards of panels each.

Roads would require the same sort of support structure a parking lot would, but you could start with interstate medians, where the panels could practically be laid on the ground. With four lanes on either side, the odds of the median being shaded are tiny. Additionally, one could attach panels to guardrails. They do not necessarily need to cover the road, but a one-foot-wide strip above the guardrails would be quite a piece of area once you installed it the entire length of a 1200-mile road.

Re:10x input != 10x output

[foniksonik]

I always think about solar power while on the freeway... here in CA it's the 405 and the 5 freeways that do it for me... 12 car lanes of completely open space traveling hundreds of miles up and down the state, with a lot of already built infrastructure, ie: wiring, conduits, maintenance terminals, etc.

Covering over the freeways with a half tube grid of cheap material... put up solar cells in grid cells where they make the most sense, let light, air and weather filter through the rest... feed it into the local grid, voila.... a huge huge solar cell array, located in the one place where it can't do anything but improve the aesthetics.

Use the cheapest stuff you can get and upgrade as those become more efficient over time...

Re:10x input != 10x output

[raygundan]

Heh-- we could build a border fence that would actually be useful! If we're gonna waste our time putting up a 1,000-mile wall everybody can climb over, we might as well put solar panels on it. Hell, you could even monitor panel output to see where somebody was climbing during the day.

Republicans: Yay! A border fence!
Democrats: Yay! Solar power!
Immigrants: This fence is MUCH easier on my hands than the old wire one!

Re:10x input != 10x output

[eugene ts wong]

I saw what you said about guardrails. If you're going that route, then you might as well aadd these to your list.

* on top of street lamps and various other posts
* bus shelters [I can't crunch the numbers, but it would be nice to see public transit give someting back to become a little bit more financially sustaining].
* wind mills [the blades, the poles, the other part]
* bus roof
* train roof

Re:10x input != 10x output

[Anonymous Coward]

This causes the $/Watt to increase

"$/Watt to decrease" or "Watt/$ to increase" (assuming that "$" means "initial investment cost", and not something like "profit made selling power, factoring in the cost of the initial investment").

Re:10x input != 10x output

[Anonymous Coward]

"Covering over the freeways with a half tube grid of cheap material"

And the concentration of vehicle pollution will be an added incentive for drivers to switch to alternative-fueled vehicles!!

Re:10x input != 10x output

[trixillion]

Yup I was being careless, what you said it what I meant.

Solar Holograms!

[tktk]

They should just make a giant hologram of the sun. Then we'd have perpetual energy.

Re:Solar Holograms!

[Anonymous Coward]

yea but think of all the power we would need to generate a hologram that awesome!! i mean, we'd have to surround it by like, a bunch of holographic solar panals to collect all the energy from it, just to power it! but if we got these new ones that are 10x as effective, then there we have it! instant 10x power infinitely generating more and more power!

yea, and i just patented that so don't even think about it!

PV efficiency & moon power generation

[Ritz_Just_Ritz]

Perhaps someday they will become efficient enough that it will be cost effective to build arrays several dozen miles square on the light side of the moon and then beam the energy back to earth as microwaves. In the absence of some sort of major breakthrough in fusion energy production, that seems like the way to go for clean energy.

Re:PV efficiency & moon power generation

[Anonymous Coward]

Why did this get a score of 2? There is no "light side" of the moon! The same side always faces the earth, not the sun! That's why the moon has phases!

Re:PV efficiency & moon power generation

[Anonymous Coward]

Just because the solar cell farm lives on the "light side" doesn't mean the microwave transmitter has to live on that side. I suspect that's what the original poster had in mind.

Re:PV efficiency & moon power generation

[argosian]

Light side of the Moon? Hunh? The lunar "day" is somewhere around 28 Earth days...fixed installations will be in shadow approximately 2 weeks at a time, and at unfavorable angles for some of the other 2 weeks.

Or do you mean build rails all the way around the Moon and motorize the panels so they can stay on the "light side". Or maybe position at the poles (too lazy to google it...does anybody know the axial tilt of the Moon? shallow enough to stay out of shadow at the poles?)

Better yet, unless you're planning on fabbing the stuff at the Moon, and maybe even if you are (to save on launch costs) just put them in geostationary orbits.

Re:PV efficiency & moon power generation

[Anonymous Coward]

> ...I suspect...

No, you don't.
Don't know nothin, dont even suspect nothin.

Sure, we'd want the microwave-beamer on the side that faces Earth. The solarfarm still rotates into the dark no matter where it is.

Re:PV efficiency & moon power generation

[Anonymous Coward]

You took that straight from SimCity. Don't even lie.

Re:PV efficiency & moon power generation

[powers_722]

Thats a great idea.

And then when Bush Jr. Jr. Jr. decides that he doesn't like [bad country here], he'll just tell the opperators to point the giant microwave systems at [bad country] country for a while.

Re:PV efficiency & moon power generation

[carpeweb]

Yeah, maybe, but that service call's going to be a bitch ... ("we can have someone there between 8 and 12 on Monday ... 2057")

We used a similar product in 2001

[goldarg]

Back in 2001 the Tucson Citizen did a project where they powered a Sun Colbalt Qube 3 off of solar power using a set of panels based on a very similar if not the same technology.

The panels they came from a company called TerraSun and the one I have on my desk left from the project looks remarkably like the one in the article.

Archive.org still has some pages from the site which is long defunct http://web.archive.org/web/20010807151516/www.sola rexplorer.net/gallery/index.php?TopicID=panels

Google finds reference to the technology that TerraSun was developing http://www.wapa.gov/es/greennews/2001/may14'01.htm

Re:We used a similar product in 2001

[Anonymous Coward]

This company is apparently the spawn of TerraSun. They acknowledge this in the PDF mentioned above (http://www.nrel.gov/technologytransfer/entreprene urs/pdfs/prism_solar.pdf), slide 3 gives the company timeline and lists TerraSun.

It's the new millenium people! Get with it!

[naasking]

I can see solar as a potential option for some businesses, but for home use you still have the small problem of no power output during the night. And that's usually just when you want some lights, television, heat, and so forth.

If they want solar to REALLY catch on someone is going to need to develop not just a cost-effective solar cell, but also a cost-effective way to store and reuse the energy collected during the day.

This is a non-issue. The technology and legislation addressing this has existed for nearly a decade: feed power back into the grid. You sell power to the power company when generating, and you buy it back when you're not generating. Simple.

Funny how everytime solar comes up anywhere, someone trumpets out this "problem". Come on people, do you honestly think such a trivial problem would go unsolved for so long?

Re: money saved with solar does not break even

Numerous studies have demonstrated that the payback for solar is anywhere from 2 to 10 years (depending on circumstances such as location). Solar cells last 10 to 20 years. You do the math.

Re:It's the new millenium people! Get with it!

[shmlco]

"You sell power to the power company when generating, and you buy it back when you're not generating. Simple."

Simplistic, you mean. Repeat after me: The grid is not a battery. Yes, you may be able to sell some excess power to the "grid", but the "grid" doesn't store energy, it just distributes it. You can't buy "your" power back again.

So to repeat, a power station connected to the grid still needs to be able to supply ALL of the energy everyone needs at home on a cold night.

"Come on people, do you honestly think such a trivial problem would go unsolved for so long?"

I think of quite a few "trivial" problems that, like this one, remain unsolved.

Re:It's the new millenium people! Get with it!

[Moofie]

"You can't buy "your" power back again."

So what? It doesn't come in different flavors. Why would you want "your" power back?

"supply ALL of the energy everyone needs at home on a cold night."

Uh huh. So you can turn off some plants during the day. Wouldn't that be a not-awful idea?

Re:It's the new millenium people! Get with it!

[naasking]

Simplistic, you mean. Repeat after me: The grid is not a battery. Yes, you may be able to sell some excess power to the "grid", but the "grid" doesn't store energy, it just distributes it. You can't buy "your" power back again.

So to repeat, a power station connected to the grid still needs to be able to supply ALL of the energy everyone needs at home on a cold night.

Fortunately, the amount of power needed at night is far lower than that needed during the day. Other power generation mechanisms are sufficient for these levels. If you want to go all-renewable, wind could provide the left over power needed at night.

Re:It's the new millenium people! Get with it!

[shmlco]

"Why would you want "your" power back?"

The point remains that once generated it's either used or gone. The grid doesn't store it. Which was the point of the original post. If we had a cost effective way to do so solar would have the potential to make a larger impact, as opposed to only operating under limited and/or optimal conditions.

"Uh huh. So you can turn off some plants during the day. Wouldn't that be a not-awful idea?"

For a rocket scientist, you're... ah... never mind. Let's just say I'd suggest you do a little research and determine just how easy it is to "turn off some plants during the day". It's not quite like flipping a light switch, and many are designed to run most efficiently at a given constant load.

Re:It's the new millenium people! Get with it!

[Jeremi]

Let's just say I'd suggest you do a little research and determine just how easy it is to "turn off some plants during the day".

I think he what he meant was, you can get by with fewer power plants, period, because the peak loads during the day would be reduced.

Re:It's the new millenium people! Get with it!

[Moofie]

For a rocket scientist, I have a decent layperson's understanding of what goes into running a power plant. Am I an expert? Well, I've never seen a municipal power grid that looks much like a rocket, so draw your own conclusions. I am not so hasty to dismiss the claims that you spend such energy rebutting. (That's almost a pun.)

I submit that, in the Southern United States (and much of the temperate world) energy costs to cool dwellings is substantial. Most of that energy is required in the daytime. Whatever excess can indeed be sold into the grid, and calculated into future sizing and demand equations by the people who are power grid scientists.

Is it simple? Certainly not. However, the idea you're so hot to get rid of has some merit, and I don't understand why it gets your undies so in a twist.

Re:It's the new millenium people! Get with it!

[shmlco]

"If you want to go all-renewable, wind could provide the left over power needed at night."

Another source that works well only under limited conditions (when the wind is blowing) and only practical in specific locations (where there tends to be a lot of wind). Like solar, both can help, but neither can be depended upon to provide and maintain constant baseline loads.

Re:It's the new millenium people! Get with it!

[shmlco]

"However, the idea you're so hot to get rid of has some merit..."

Never said it didn't. In my original post, however, I made the statement that solar would have a larger impact if we could develop a safe, cost-effective mechanism for storing the power produced so we have can have power at night and during non-optimal periods (cloudy, rainy days).

10x input != 10x output-Solar Cell.

[Anonymous Coward]

Hmmm. Whatever happened to tuned antennas as an energy collector? You could layer them to catch the entire light spectrum. Of course one could use the ionosphere instead.

That's not the point

[m85476585]

It won't save any space compared to regular PV cells, but assuming that area of holorgam is cheaper than area of silicon (The article implied that), then it will save money.

Rainbows==Pretty

[N. P. Coward]

Who cares if it works better or worse than existing technology?

If we all installed these panels, everyone would have a 3D rainbow on the roof!
Ooooo, aaaahhh.

Re:Rainbows==Pretty

[klang]

You'll just be sitting there minding you're own business. And they come marching in and crawl up your leg and start biting the inside of your ass. And you'll be like. Hey. Get out of my ass you stupid rainbows.

How about Fresnel lenses?

[dinther]

Concentrating light onto PV cells has been done before. The main problem is that the PV cells get too hot and degenerate quickly. Bulky panels using mirrors or lenses can be solved using flat fresnel fenses. Now the question remains, how to cool these things. It dawned to me that the panel created so far is in fact very similar to the solar water heaters. Why not combine the two? A fresnel lens concentrates the light onto a PV panel that is protected against heat by water flowing up between two layers of glass (Hot water rises) circulating as it does in traditional solar hot water systems. The water takes out the heat producing IR radiation leaving all the good electricity generation radiation for the PV panel. This way you can put up one panel producing both hot water and electricity.

Re:How about Fresnel lenses?

[aaarrrgggh]

I've always wondered why they didn't do something like that. You would want the water on the back of the cells though so it doesn't absorb any of the incident energy.

Re:How about Fresnel lenses?

[Steavis]

I actually asked a similar question to a PV install vendor here, since our desert temperatures are around 45 Celsius during the day. This reduces the output of panels (which are rated at 25 Celcius) significantly, and it would seem ideal to cool the panels with water and pre-heat your hot water system, spa, etc.

The problem is, if you are grid-tied or have a certified installer work on your system, they are extremely reluctant to even talk about mixing liquids with electricity. Often they tie the panels together in series resulting in very high (several hundred) DC voltages being sent to the inverters. You also have to comply with local and federal electrical codes plus whatever constraints your utility has (if you grid-tie).

I'm not saying it couldn't or shouldn't be done -- it seems like a great idea to extract even more energy in the form of heat while increasing efficiency. It's just that few are willing to attempt safely putting the two together for consumer applications. I mean, can you really see Joe sixpack being careful when one of the components dies, leaks, or otherwise needs service? "It's just solar panels and water, can't really be all that much juice!"

Re:How about Fresnel lenses?

[dmiller]

IANAOE, but an obvious solution would be to use selective mirror, prism or diffraction grate to permit only the wavelengths tho which the PV cells are sensitive through. In particular they could eliminate the IR portion - IIRC no PV cells are really sensitive to this section of the spectrum.

Re:How about Fresnel lenses?

[z1234321]

I agree. In an old PopSci article, they mentioned that solar cells with fresnel-type lenses were used on Deep Space One to boost the output. The article is at http://www.solarviews.com/eng/deepspace1.htm[solar views.com]. FTA: "The solar panels, designated SCARLET II (Solar Concentrator Arrays with Refractive Linear Element Technology) constitute one of the technology tests on the spacecraft. A cylindrical lens concentrates sunlight on a strip of GaInP2/GaAs/Ge photovoltaic cells and acts to protect the cells. Each solar array consists of four 160 cm x 113 cm panels."

Re:How about Fresnel lenses?

[bensch128]

If you read the article, it says that lens don't work because they have to be always facing the sun -> heavier/more expensive.

The hohlgraphic plates can redirect light coming in from any direction and cause it to eventually (after much bouncing around) fall on a photovoltaic cell. It also has the benefit of filtering out bad (unhelpful) IR light.

Cheers,
Ben

Re:How about Fresnel lenses?

[Anonymous Coward]

This little lone inventor is just starting up production of his prototypes with fresnel focused solar.

He seems to attract a lot of skeptics but he battles on and he might just kick a goal.

A web designer he ain't: http://www.greenandgoldenergy.com.au/

Have to wait for a few months to see how it all turns out...

If it does work out OK then a low cost clone from an Asian manufacturer will probably win the day anyway :-(

Plain old plants anyone?

[Anonymous Coward]

What I don't understand is this - the greatest solar cells are plants. Green - both literally and figuratively. May be the question we should be asking is this - why are we consuming more energy per human than any other animal?

The short-sightedness of the human race would be baffling if it was not so depressing.

Re:Plain old plants anyone?

[Xiroth]

What I don't understand is this - the greatest solar cells are plants. Green - both literally and figuratively. May be the question we should be asking is this - why are we consuming more energy per human than any other animal?

There's an interesting point there, although then you went off on a tangent.

Better question: If the greatest solar cells are plants, why don't we use the reaction they use to generate energy?

Re:Plain old plants anyone?

[patio11]

Because the efficiency of sunlight -> sugar -> atp -> electricity is even worse than sunlight -> photovoltaic cell -> electricity to say nothing of coal -> fire -> steam -> mechanical energy -> electricity.

Re:Plain old plants anyone?

[Anonymous Coward]

How about grow plants, burn plants to generate steam, turn a turbine generate electricity.

Re:Plain old plants anyone?

[Anonymous Coward]

May be the question we should be asking is this - why are we consuming more energy per human than any other animal?

Because they don't run Linux.

Re:Plain old plants anyone?

[Anonymous Coward]

Duh, we are using the reaction generated by plants as an energy source. In fact, that is our PRIMARY energy source. Its the food chain. Plants grow, burger-producing cows eat the plants, we eat the burger = energy.

The problem is in the inefficiencies. Motorised transport needs a higher conversion ratio than plant material can offer directly. Of course, this doesn't preclude what is done with bio-diesels etc. We just don't really want to be driving the SUV with a great big mucky haystack on the back.

And taking that one step further, even oil and coal are derivatives of the photosynthetic reaction.

Re:Plain old plants anyone?

[Muchsake]

Hey you missed an enery source. It should be
Plants Grow
  Cow eats plants
        collect methane generated by cow
            Turn cow into burgers
                Cook burgers with methane generated by cow.

Re:Plain old plants anyone?

[Alioth]

We do. It's called biodiesel. Or in a more simple form, a wood burning fireplace. Or a steam train.

$ per Watt

[TubeSteak]

http://news.com.com/A+high-tech+way+to+defrost/210 0-11395_3-6061333.html

"We built a solar cell made of ice," he recalled. "While it is not as efficient as a silicon solar cell, it costs a penny a square mile."

We can make super cheap photovoltaics, but you have to factor in usability. There's a very limited part of the world where you can use a solar cell made of ice.

Also, silicon solar cells aren't going to get any cheaper in the near future. The demand for polysilicon has been booming and (like oil) the refining/purifying capacity hasn't kept up.

cost per watt

[maino82]

the article states that they are shooting for a price around $2.4/watt, which I can assume ytou is well below what we are currently paying. i was recently quoted a price of $8/watt from solarsave (http://www.solarsave.com/) for a pv installation, so having to pay a third of that price is extremely reasonable from a cost per watt perspective, even if you don't get any added efficiency due to heat losses.

Pointless.

[zippthorne]

This scheme removes one of the principle benefits of photovoltaic power: namely that it's omnidirectional: it'll still have a decent energy production even if the light source is diffuse. like.. say.. light, but full cloud cover (seems half the weather in the NE is light full cloud cover...) or fog. if you're going to bother lensing the light, you might as well use a solar collector to drive a heat engine, which is far more efficient than PVs are right now.

Re:Pointless.

[Anonymous Coward]

This holographic collector is not directional, as lens based collectors are.

Re:Pointless.

[Anonymous Coward]

Pretty close to true. Fog or clouds block 95%-99% of the light, so you can forget solar during those times. Heat engines have huge hurdles to overcome before they will be ready for solar. The best ones are turbines and use exotic materials, like toluene "steam" (organic rankine cycle) with eff approaching 30%. Problem areas are the pointing device/receiver, pumps/valves/piping, power converter, maintenance. Simple reciprocating steam engines have terrible efficiency (10% or less). In short, TANSTAAFL.

Cost is the primary draw...

[doormat]

The fact that these panels are much cheaper to develop and output the same power as a conventional PV panel is where its at. If they can get the price down to $1.50/W, it starts to look really appealing. For an installation of 10 200W panels (2kW), you're looking at saving $2000.

One of the other factors with this panel is that it brings down the net carbon impact of the devices. It takes less energy to produce these panels, so the breakeven time is much shorter than on a conventional PV panel.

However, the biggest price hurdle is actually the cost of a licensed electrician to install the equipment. Cheap panels are nice, but its got to get to the point where you can "plug and gen" instead of paying out the ass. Have you priced labor in the trades lately? In my town, apprentices are making $30/hr, master electricians, plumbers, etc make $50+/hr.

Re:Cost is the primary draw...

[Anonymous Coward]

"output the same power as a conventional PV"

Just like AAA batteries output the same power as a car battery? Sure, if you had enough of them.

These panals would output less power, per area, than conventional PV panals. They don't give any collection efficiency numbers, but I am certian it's nowhere near direct exposure or other means of concentrating. How much area would you need to get 2kW? Do you have enough roof space? :)

Re:Solar cells aren't about storing energy.

[vertinox]

Here is the deal...

When solar cells are used, they are feed directly into your houses power supply and any excess electricy produced goes back into the power grid. Not stored in batteries.

This seems rather odd, but when electricity goes back into the power grid, it spins your meter backwards. Anytime your meter goes backwards, you get cash back from your power company.

Soo... You are still depedant on your local power grid for nightime power, but perhaps that might change for people who want to not have anything to do with their power company.

Still... Because of tax benefits, the money you receive from your power company is usually more than you pay them per watt.

More info can be found at the Home Depot Solar Power installation site. I looked into it mostly out of curiousity and my plans on being a new home owner, but I think the costs might be still too great to be worth the installation.

Aesthetics

[syphax]

One interesting aspect is that these things seem to be pleasant to look at.

Aesthetics are an important issue for solar collectors, because if we want to generate any significant amount of power from solar, we are going to be looking at a lot of them. On average, with 10% efficiency, you can generate about 150 kWh per year per square meters. US electric power generation in 2004 was about 4 trillion kWh, so if solar were to provide even 10% of that, we'd need to cover the better part of Rhode Island with cells. If you were to provide 100% of total US energy consumption with solar (no, I'm not suggesting we do that), I think you'd need 1-2 Maines.

Re:Aesthetics

[Charcharodon]

We already have fore more than 1-2 Maines already being used in the US, they're called buildings. By requiring all new buildings to have a minimal amount of PV cells or solar hot water heating installed, a great deal of power can generated simply through new construction.

Start off with an insignificant amount per new home, say a 1000 watt inerty system and/or enough solar hot water for 4 people, and up the amount every decade or so until the thing becomes self sustaining.

After visiting Hawaii I am convinced this is feeseable. Nearly every home I saw in Maui had solar hot water heaters on them, and nearly every business had a PV array and solar hot water heaters on their roofs.

Re:Aesthetics

[MrCopilot]

if solar were to provide even 10% of that, we'd need to cover the better part of Rhode Island with cells. If you were to provide 100% of total US energy consumption with solar (no, I'm not suggesting we do that), I think you'd need 1-2 Maines.

Finally, a use for Nevada/NewMexico/Arizona/Or any of those old Nuclear test sites.

.... It's Pronounced Nuk-U-Lar ... Homer Simpson or G.W. Bush, I can't recall. Ok, that one is definately G.H. Bush

Re:Aesthetics

[Gorshkov]

After visiting Hawaii I am convinced this is feeseable. Nearly every home I saw in Maui had solar hot water heaters on them, and nearly every business had a PV array and solar hot water heaters on their roofs.

Try visiting the northern US or ...... *gasp* .... CANADA - preferably in Feb, and see how convinced you are.

You've heard of Canada, right? The place with about 8 hourse of daylight PERIOD per day that time of year? Scandanavia, Russia ....... pretty well anything outside of the tropics.

In Hawaii or Arizona/California/Florida, etc, you have a perfect situation. You have the most sunlight when you need the most power (for AC, etc)

Most of the rest of us, however, are in a diffferenct situation. We need heat at night. Hell - I grew up in Labrador, where we had to plug our cars in, both day AND night, if we didn't want the oil inside to freeze solid.

Hawaii might be able to go %100 green ...... but it's very much the exception, not the rule.

Re:Aesthetics

[Anonymous Coward]

You'll find, when looking at Canada, that there are bugger all people up there. Most of the houses are down south, where the sun is better.

So, if 50% of the housing is PV'd, that is 50% of your power needs taken care of.

Now, how much is lost in transmission? About 30%. So now all you need is ~20% new installation in nevada to cover the rest.

And ANYTHING generated by the remainder is pure gravy. Store it or use it to generate products to sell.

Re:Aesthetics

[Gorshkov]

You're missing the point, which is that the people who use the MOST power (heating, lighting, and yes, air conditioners in the summer) can use solar the least - because we don't get as much as you do.

Solar, Wind, Hydro, etc - all "natural" power sources depend on the location - and where you are is not always where *it* is

Re:Aesthetics

[Charcharodon]

I have a Labrador, his name is Max

I got Max in South Dakota, that's pretty close to Canada, solar works just fine up there.

I'm getting off the subject of this response. Who cares about Canada and Scandanavia, or Russia, the original response to the response, on which I commented was that it would take an insane amount of surface area to switch to solar in the US and I responded that we already have plenty of empty roof space here, so exactly what does this have to do with Canada? Other than maybe that we should be switching to solar so more carbon based things can be left for those up north. Course we could always send some power lines up your way, we like Canada.

Re:Aesthetics

[Gorshkov]

Actually, most of the power lines flow south, to help you lot out already. So I guess maybe you *should* care about Canada.

Cost is the primary complaint.

[Anonymous Coward]

"However, the biggest price hurdle is actually the cost of a licensed electrician to install the equipment. Cheap panels are nice, but its got to get to the point where you can "plug and gen" instead of paying out the ass. Have you priced labor in the trades lately? In my town, apprentices are making $30/hr, master electricians, plumbers, etc make $50+/hr."

Man. First of all you all complain about CS, IT and outsourcing. Then suggest people become plumbers or electricians. Now you all want to do to those professions the same thing that happened to IT (The Wal-Marting of IT). Next up, HB-1's for the trades.

many diffraction gratings are holographic

[Anonymous Coward]

Um, hey guys. I think you'll find that many high quality differaction gratings are in fact *holographic.*

When it comes to making diffraction gratings, phase-delaying gratings beat out amplitude-reducing gratings (parallel opaque parts) for transmission. It's easy to make both phase and amplitude gratings with an interferometer (to make fringes) and some holographic film. For phase gratings, you just bleach the film/plates after you wash them in developer and before you use the stop bath.

Three dimensional graings also be used to achieve high efficiencies. I've made some by projecting interference fringes into an optically active crystal (see the photorefractive effect). Optical quenching is a wild effect.

~opticsdoug

Re:many diffraction gratings are holographic

[JohnFluxx]

Hi. You say "many", but I can't think of what would be a diffraction grating and _not_ holographic.
You can have an amplitude or a phase or a phase-and-amplitude hologram in transmission or reflection.

Question I've had in my head for awhile...

[Bohiti]

Our planet has been doing just fine with the energy the Sun is sending us for billions of years.

Are there any concerns about a wholesale switch to alternative energy, like wind, hydro, solar? We are taking energy from nature and using it in ways much different than what is was previously used for (heating the earth, keeping the clouds and rivers moving..)

Is there a chance we could cause some sort of global change, climate or otherwise?

Then again, I'm not a big believer in global warming, so I'll just tell myself to "stop worrying, we shouldn't be so conceded to think that we can affect the planet like that."

Re:Question I've had in my head for awhile...

[pjay_dml]

First of, it is not about "believing" but trusting scientific methods and the data collected with those tools by the scientific community (science only works collectively).

"We are taking energy from nature"
You may want to brush up your basic physics knowledge. You can't take energy from nature, as we are an integral part of the system. What may occur is energy conversion.

And you might also want to learn about the technologies you don't believe in (Gallileo all over again - sigh).
With any human activity there are issues and problems, the point of interest is the human controllability potential.
Solutions based on fossil and nuclear fuels, have a low controllability potential, which reverses with (most) regenerative technologies, as the controllability potential is the motivational factor in developing these technologies in the first place.

This brings us to the pseudo conflict between "green terrorists" and "natures bastards", a conflict of world views. The former views humans as a part of nature. The later view humans as the owners of nature. I label these view points "scientific minded" and "dogmatic minded".

Already by existing we are changing nature, creating global change on some level. What we need to ask is rather, what might the outcome be of certain behaviour patterns. This is where the concept of "global warming" comes from. Scientists looked at our behaviour patterns, and at the changing patterns found in our natural environment.

In the end it doesn't matter what we believe, but what the outcome of our behaviour will be, due to existing natural laws. Disregarding science will only extend the harm we are currently unleashing upon ourselves. You may be sceptical towards current theories of science, as they keep on changing (the nature of science). Never the less, what you can't deny, is that science has been THE tool, offering us the best advice when faced with difficult and complex problems, ensuring our survival as a species.

Re:Question I've had in my head for awhile...

[99BottlesOfBeerInMyF]

Our planet has been doing just fine with the energy the Sun is sending us for billions of years.

I doubt anyone feels global warming is a threat to the planet. It is, however, a threat to humans and other animals that live on the planet. Over the last 4 billion years the earth has spent as much time in climactic states that none of us would want to live in as it has in states that are what we consider the norm today.

Are there any concerns about a wholesale switch to alternative energy, like wind, hydro, solar? We are taking energy from nature and using it in ways much different than what is was previously used for (heating the earth, keeping the clouds and rivers moving..) Is there a chance we could cause some sort of global change, climate or otherwise?

Radiation from the sun hits the ground warming it. If instead radiation from the sun hits a solar panel, 10% is turned into electricity (the remainder going to waste heat where it did before) and that 10 percent is used to run appliances (turned into mechanical energy which again bleeds off into waste heat eventually) all it does is move the energy around a bit. There is concern we could interfere with an existing energy exchange system, like ocean currents or jetsreams, with unknown results, but I've never seen a proposed energy collection method that would have such an affect. The only thing I've seen created by humans that does pose some risk to upsetting such a system is increased global warming.

Then again, I'm not a big believer in global warming, so I'll just tell myself to "stop worrying, we shouldn't be so conceded[sic] to think that we can affect the planet like that."

It is not conceited to think humans have an effect upon the planet's climate any more than it is conceited to think all the fish in a river died due to pollution from humans. To write off a potential problem this serious on the grounds that humans can't be causing a change that large a change, with no evidence to support that assertion, is very illogical. The best way to determine what is happening, and why, and what can be done is simply to apply the scientific method. The best research I've seen tends to indicate that what is happening is the planet is getting warmer, it is likely being caused or exacerbated by various actions of the human species, and no one really has a good way to stop it. We may all die as a result of this, but I don't think that is likely. Rather, I think a lot of us may die and others may have to change the way they live drastically.

At least a 50% transmission loss through Hologram

[Anonymous Coward]

Holographic enhancement has to overcome the 50% transmission loss through the hologram. No numbers here to see if this panel is close to compensating for the transmission loss. Also, no numbers on the manufacturing cost.

(1(kW/(M^2))*.1)=100W/m^2

[HornWumpus]

That's not all that much land. 4 square kilometers of collector aligned to the sun would produce about 400MW (equal to an average nuke plant). Granted it would only get that amount at near noon.

But only tree hugging idiots think in terms of ALL solar.

Maine would be a bad choice though.

Re:(1(kW/(M^2))*.1)=100W/m^2

[syphax]

But only tree hugging idiots think in terms of ALL solar.

It's a scaling exercise. I am not suggesting we cover a single state with PVs (I'd have to go with AZ or NM in that case), I just want to provide a sense of scale.

My point is that any significant use of solar energy (which I am a huge proponent of) will require a non-trivial use of land. Nogt a deal killer, but not something that can be ignored.

Re:(1(kW/(M^2))*.1)=100W/m^2

[nasor]

You seem to be confusing the total solar flux on the earth (which is indeed about 1 kw/m^2) with the solar flux on the earth's surface, which is substantially lower. Only a small fraction of the total solar energy that strikes the earth ever reaches the surface; most of it is reflected, scattered, or absorbed by the atmosphere. By the time sunlight reaches the ground you only have a flux of around 70-200 watts/m^2, depending on where in the world you live. As I recall the average solar flux on the U.S. around 150 watts/m^2; so you would need around 30 square kilometers to produce your 400 MW.

This is why some people like to talk about putting solar panels in space to send power back down to earth; your solar panels get a lot more power.

Re:(1(kW/(M^2))*.1)=100W/m^2

[InfoVore]

My point is that any significant use of solar energy (which I am a huge proponent of) will require a non-trivial use of land.

Great example of how language limits our thinking. If you said "will require a non-trivial use of area" instead, then we get to consider all kinds of other interesting ideas like:

- Orbiting solar power arrays
- Floating artificial islands covered in solar collectors(preferably anchored at the equator)
- Multi-kilometer diameter greenhouses, each with a kilometer high generating tower (essentially a BIG solar air heater with a central hot air turbine generator "smokestack")
- BIG upper atmosphere dirigibles covered in polymer based solar collectors.

Certainly none of those is as easy as covering New Mexico in solar panels, but they are possibilities.

Frankly, I don't think the problem is power generation or solar cell efficiency. I think the real problem is storage. If we could make cheap, small power storage units we could generate electricity in a number of ways then draw it only as needed. If only the high-speed flywheel storage cells that were being researched a few years ago had worked out, we could eliminate most transmission inefficiencies and more easily plug into lots of different sources for generating our power: fossil fuels, nuclear, solar, wind, etc. You could generate and store on site, or you could pay a supplier and have your power delivered via truck once a week, ala milk deliveries of yesteryear.

I.V.

Actually, that is very important

[Ogemaniac]

I was just going to comment that these solar cells LOOK a heck of a lot more pleasant than the plain black ones. To pretend this does not matter would be a mistake.

This reminds me a lot of the wind generator debate. Some people really loathe them, while some people find them rather pleasant, actually. Me included, of course.

Re:What happend to that South African break throug

[Anonymous Coward]

There's not a whole lot of press about it, but apparently there's one company in Germany cashing in on the government subsidies to manufacture using their tech. Other than that, AFAIK and AFAICFO, he needs to effectively sign up semiconductor fab space & convert it to make his cells - and AFAIK and AFAICFO he's unwilling to let China touch it.

It Doubles the efficency....

[Infosmith]

This can obviously double the efficency of a typical solar cell. The hologram can redirct the "useless" infared onto solar hot water collectors, whilst the "useful" light frequencies go into the solar cell. Most homes need both Electricity and also hot water. Difficult to achieve any other way.....

Solar Nanotechnology

[Trek1394]

It has come to bear with recent advancements in nanotechnolgoy that up to an 80% increase in solar cell power output is possible.
"Recent nanotechnology breakthroughs in regards to solar have promised new solar cell designs capable of capturing a much wider range of solar energy, which would be much more efficient at converting solar energy to electricity (approaching 60% efficiency), more versatile (able to be painted onto just about any surface), and less costly than today's solar technology. These nanotechnology advancements in solar energy technology appear to be finally advancing solar beyond it's initial silicon-based limitations."
http://peswiki.com/index.php/PowerPedia:Solar_Ener gy

Pyron Solar Has Got This Company Beat...

[wynand1004]

Pyron Solar http://www.pyronsolar.com/US/index.htm has got a great little system put together that uses fresnel lenses to focus sunlight on high efficiency solar cells.

They float the entire assembly in water to cool it and to assist in rotation so that the apparatus can follow the sun.

Our energy problems are licked, I hope.

Re:Pyron Solar Has Got This Company Beat...

[dwk123]

Interesting - Pyron is obviously going for the 'power plant' market, which IMHO is likely to see a lot of activity in the near future. With rising oil prices, larger scale concentrating solar plants will be competitive in the southwest. These guys http://www.greenandgoldenergy.com.au/ are doing much the same thing at a domestic scale. Using the same Boeing/Spectrolab panels.

Skeptics: this is NOT just a glorified Fresnel lnz

[Starker_Kull]

My first thought reading the headline was that this was just called a "hologram" to get some buzz, over what is a very generic, straightforward way of increasing the power delivered to the expensive part, the solar cell. But (for those too lazy to RTFA) this is different for three reasons:

1) It is almost omnidirectional - a Fresnel lens is a flat subsititue for a regular lens, with limited off-axis focusing ability. This seems to use the glass as a lightguide instead, with a broader angular reach (in exchange for limited scalibility - bigger the glass width to thickness ratio, the more light lost because of increased internal reflections & distance from entrance to cell)

2) It uses a hologram to selectively reject useless frequencies like infrared, which is 80% (IIRC) of the energy of sunlight, but generates no electricity from the cell. In fact, infrared is harmful to the cell, because it increases its temperature, which reduces its effeciency!

3) Because of the above features, it does not need a turning mechanism to follow the sun, the solar cell (which is the most expensive part) lasts much longer because it is not heated as much even though it is capturing much more useful light and converting that into electricity, it is flat and relatively easy to handle, unlike traditional solar cells with large, bulky, moving "capture" mechanisms placed in front of them....

In summary, it is cheaper per kilowatt-hr, AND more effecient, AND more practical for installation (no moving parts or seperated pieces). This is pretty neat.

Just to be clear on wording

[raygundan]

I believe you probably meant this, but your wording is a bit misleading.

You still need the same number of *panels* with this new technology. They are not more efficient per area than normal panels built with the same type of silicon, and probably slightly less due to loss in the diffraction.

But you need less silicon per panel, since most of the panel is just a cheap holographic diffraction grating that directs light towards the small strips of silicon.

You'll still need your whole roof, or whatever-- but it will cost less.

go solar!

[Jasper__unique_dammi]

I happen to know a whole range of organisms which rely only on solar power, never heard them complain about a blackout. I know only one species of organisms that uses a whole range of power sources, and they are whining about energy all the time!

Not true, oddly enough...

[raygundan]

Photosynthesis is well below the efficiency of commercially available solar panels.

"The net result being an overall photosynthetic efficiency of between 3 and 6% of total solar radiation."

"Typical solar panels have an average efficiency of 12%, with the best commercialy available panels at 20%, and recent prototype panels at around 30%."

Not $/W, think W/W

[AJ Mexico]

The true figure of merit for solar collectors is not $/Watt. Many photoelectric solar cells are in danger of requiring more power to manufacture than they will ever deliver during their lifetime. They still may be economically effective since they are built using cheap power from oil. This is great if you just need the power in a remote location. But don't fool yourself that you are solving the energy crisis. See http://www.dieoff.org/ and look at "Economic Efficiency"

The subject article may improve both $/Watt and Watt/(Mfg Watt), if the concentrator requires less power to make than the solar cells. So much the better.

Re:Not $/W, think W/W

[Anonymous Coward]

Laserjet original price $7000 for a slow piece of crap.
Digital watch original price $500 for led time+date.
same story with Microwave, CD Burner, DVD Burner, you name it. Cost of manufacture and efficiency are both engineering problems that can be solved. Sorry but your mad max fantasy aint likely to happen..

Av vs Max output.

[Retric]

You can get ~1000w/m^2 of light for about 8 hours a day with a good tracking system on a good day in the right area, dropping down to next to 0 at night. In space it's ~1200w/m^2 24/7. So on average you can only get ~1/5th or 200w/m^2 but that's an average over the total day not the max net power per given area which is what the grandparent was talking about.

EX: http://www.popsci.com/popsci/energyefficiency/7c53 0b4511b84010vgnvcm1000004eecbccdrcrd.html

~pi * (32/2)^2 ft^2 in m^2 = ~74 m^2 = 25-kilowatt giving you ~338w/m^2 of electricity.

Note: The system is about 40% efficient per area of the mirrors, but there is a shadow of the sterling engine in the middle, which reduces the efficiency per unit area.

Anyway, while the average output is important the fact that the max power output follows max power demand is vary useful. A 1000MW power plant does not average 1000MW over a year it's simply the maximum power output, which you try and map to max demand. There is a large gap in AC usage in the summer between 2PM and 2AM. So while the average power output is important if you want to go 100% solar and ignore things like wind it's not really all that important from an adoption standpoint because 2AM electricity is worth much less than 2PM electricity due to supply and demand.

Re:Av vs Max output.

[Anonymous Coward]

which you try and map to max demand

"try to map".

Note that the only place (of which I can think) where "try" should be followed by "and" is in the phrase "try and try" (e.g., "I try and try to refrain from correcting other people's spelling and grammar errors, but success continues to elude me.").

Re:Pointless. (BAD MODS)

[evilviper]

This scheme removes one of the principle benefits of photovoltaic power: namely that it's omnidirectional:

NO IT DOESN'T DO THAT AT ALL... QUITE THE OPPOSITE IN FACT. AND CLEARLY THOSE MODS THAT GAVE YOU POINTS DIDN'T RTFA.
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Post Comment
Lameness filter encountered. Post aborted!
Reason: Don't use so many caps. It's like

One more advantage

[Anonymous Coward]

The hologram may extend the life of solar cells. Providing a barrier to hail and infrared heating.

10x input != 10x output-Human nature.

[Anonymous Coward]

Of course geeks in there zeal for all things technical forget about human nature. Right now because of the demand for copper people are stealing it left and right. Solar panels would also be stolen and otherwise vandalized.

Re:10x input != 10x output-Human nature.

[raygundan]

A PV panel isn't like copper-- it can't be "melted down" and sold. You'd have to sell the actual panel, and it doesn't seem like it would be hard to watermark the silicon to close any black market that might arise-- think VIN numbers etched like the circuits in a microchip. The panels are, after all, big chunks of the same silicon. Hiding a few million ID numbers per panel ought to be easy, and you're not gonna file them off without destroying the panel.

If we cover everybody's rooftops in the first place, where are they gonna put the ones they steal? The hoarders should be easy to spot. :)

Vandalism, on the other hand, is a likely problem. I don't think it's one that makes the whole idea invalid-- it will lower the overall net efficiency, but I doubt even the most diligent vandals could paint over more than a tiny fraction of a nation-sized solar infrastructure, particularly when much of it is on the rooftops of individual homes. We don't have much of a problem with rooftop vandalism here, but I can't speak for the whole country. Perhaps there are roving gangs of shingle-taggers in suburban Nebraska I am unaware of.

W/W is better than 1/5 on average

[raygundan]

While panels may not be economically reasonable in most areas (they are cheaper to use than the grid in locations like Hawaii already), they are certainly net-positive on their production energy.

Depending on the type of panel you're talking about, the break-even time is 3-5 years, for panels that will last several decades. Show me another way to invest 3 watt-hours and get 20 watt-hours in return, and I'll be a wholehearted supporter of that, too. They are indeed energy-intensive to manufacture-- but they are also capable of producing energy above that many times over.

The particular design this article discusses would improve that payoff time by roughly 10x, as well-- going from five years to six months, since they're using a tenth of the silicon.

Half the performance at a third the price = winner

[raygundan]

I definitely want to see final cost numbers. Their target price is such a bargain that if they hit it, it would be cost effective compared to normal panels even if they're only a third as efficient. At half the performance, but a third the price-- these are still the dollar-per-watt winner.

But we all know that predicted prices and not-in-production experimental products have a way of not turning out like the rosy predictions their inventors make.

The biggest deal with this is that there is currently a supply bottleneck in getting enough good silicon to meet panel production demand, since it requires so much of it and they must compete with the chip industry. If they can suddenly use 1/10 the silicon, they can stretch their limited silicon supply into ten times the panel production. I hope this pans out, and that the patent holders license it to everyone they can find.

But I'm not holding my breath.

I don't work in optics...

[exp(pi*sqrt(163))]

...so I'm no expert. But thinking about my little diagram for working out what angles give constructive interference I grokked what you mean by "phase-delaying gratings". I'd never met the concept before, but it's pretty obvious that the idea could work without the cost of eliminating half of the light impinging on the grating. Neat idea. I feel like I actually learned something today. Thanks!

MIT's Tech. Rev. thinks light bends light!

[Carlk]

HOLOGRAMS are interference patterns of light which the eye-brain interpret as solid.

Aren't they confusing the prismatic wiggle pictures with Holograms"?
I assume Technology Review , an MIT Enterprise means a prismatic or freznel lense.

Re:MIT's Tech. Rev. thinks light bends light!

[Sleet01]

Holograms are sections of mirrors, created by the interference of coherent light beams, which reflect light in such a way as to recreate images of the original subject from different angles. The reason that our brains perceive three dimensions is that each eye is receiving a slightly different image; the light has to travel slightly different paths through the mirrors to reach each eye, creating a parallax effect. Holograms are considerably more effecient than fresnel lenses because they are fundamentally different: holograms consist essentially of concentric sections of parabolic mirrors (IIRC) while a Fresnel lense is a series of concentric spherical lense sections.

I'm trying to remember the book I read which contained this description of how holograms work; most web sites just call holograms a kind of interference pattern or diffraction grating, without going into the details.

Re:Skeptics: this is NOT just a Fresnel

[Carlk]

"RTFA"? I did. It did NOT elaborate.

The discussion "holograms - ismirth" says:

Rainbow transmission holograms are formed as surface relief patterns in a plastic film, and they incorporate a reflective aluminum coating which provides the light from "behind" to reconstruct their imagery. Another kind of common hologram is the true "white-light reflection hologram" which is made in such a way that the image is reconstructed naturally using light on the same side of the hologram as the viewer.

Prismatic or interference, still sounds like spectral separation, not a hologram.

It's not the efficiency per sqm, or even buzzwords

[Geminii]

It's interesting because it's a "missing-link" technology. Cheaper solar power for the masses. It can be used to increase sales and interest in the solar industry in general, allowing research into more efficient technologies to be funded more rapidly.

not an improvement

[PermanentMarker]

Just red the article, so a hologram based 'miror' ads about 10% wel imagine they can improve 20% of light. While a real mirror adds 100% or more a by redirecting light focus. They better could have went to cannon or some lens company building cheap plastic micro lenses on top solar materials, or use micro mirrors. So what's their technology improvement, esthetics ????? the next B&O electronics company for solar pannels ????

nothing new under the sun...

[elFisico]

This idea has already been implemented several years ago where this kind of setup (solar panels and holographic gratings) was incorporated into office windows, directing the usable light frequencies towards the panels but still leaving enough normal light through so rooms don't get too dark. I think they even deflected the far infrared away so the heat stayed out of the building!

Can't remember the report too clearly but I think it was an office building in France...

Re:What happend to that South African break throug

[Anonymous Coward]

ZA breakthrough was in cell crystal structure. This breakthrough is in cell mounting. They're not mutually exclusive. The two are mentioned separately because of separate research groups at separate institutions, and because why jinx venture capitalists with non-exclusive PowerPoint slides?