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New Solar Panel Design Traps More Light
Posted by
CowboyNeal
on Thu Apr 12, 2007 09:57 PM
from the thousand-points-of-light dept.
from the thousand-points-of-light dept.
GoSun wrote in with an article about new solar panels that opens, "Sunlight has never really caught fire as a power source, mostly because generating electricity with solar cells is more expensive and less efficient than some conventional sources.
But a new solar panel unveiled this month by the Georgia Tech Research Institute hopes to brighten the future of the energy source." The new panels are able to produce sixty times the current of traditional models.
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brighten up? (Score:4, Funny)
you want a dim future
60 times the current ... (Score:5, Funny)
Wrong way (Score:3, Interesting)
--
Eat the reflectance and get it now: http://mdsolar.blo [blogspot.com]
Catching Fire (Score:5, Funny)
Well, I always saw that as a good thing, I don't know about everyone else here...
Re:Catching Fire (Score:4, Funny)
Insects FEARED me... Mueyhahahahaha...
Parent
*yawn* (Score:4, Informative)
This is non-news. Multi-layered cells have been talked about forever, and haven't they all previously run into similar issues?
(*yawn*)* (Score:5, Funny)
Parent
not quite (Score:5, Informative)
Said multi-layered approaches use multiple pn junctions with differing band-gaps, all on top of one another. This allows them to capture a broader spectrum of incoming light energies, thus increasing efficiency.
The approach referred to in this article is attacking a different problem - using a 3-D 'nano-tower' construction for the pn junctions in order to minimise the reflection of light, thus capturing more of it and therfore being more efficient.
While I'll agree that even this idea for such nano-cells has been around for a little while, it is still in very early stages of development, and has a long way to go. It is encouraging to see apparent evidence that the concept does work, however!
Parent
Efficiency is not really important (Score:5, Insightful)
If you can get low $/watts with low efficiency that would be OK. Tile your house with the stuff, use it as the external covering for buildings.
That is one of the major problems with PV showcases like the Australian solar race. they push efficiency more than $/watts which is my the winning cars cost hundreds of thousands of dollars.
Bullwhoey (Score:4, Insightful)
The power convesion ratio is not really that important in itself. The only really important measure is $/watt.
Right, and the only thing that matters with hard drives is $/GB ratio? People don't size systems based purely on $ figures; required output weighs into the equation heavily, since systems usually pay themselves back pretty fast. It doesn't matter when you have a whole hillside or roof, but otherwise, size is important, and the more efficient a panel, (duh), the smaller. That matters for space availability and wind loads.
For example, it's not practical to put solar panels on the roof of a UPS truck; you could cover the entire roof, and even on a sunny day, you probably still wouldn't be able to supply enough energy to keep it going on a day's worth of deliveries. Increasing the efficiency matters here. Likewise for say, putting a solar panel on the back of a cell phone.
The other arena this helps in? Wind loads. If you have a residential system with several panels on a tracking frame, if the panels can be half the size, that means a cheaper frame and tracking system, and less of an eyesore in your back yard. Or, alternatively, twice as much power from the same frame.
What really matters is retail availability. I've been reading about advances in solar panel technology for years, and it's dripping into the consumer market like molasses. Why? Well, for one thing, oil companies are snapping up solar intellectual property and companies like crazy...
Parent
Re: (Score:3, Insightful)
If you assume that evolution always finds the cheapest solution, you can conclude that it's cheaper to have low efficiency photoconversion, as plants are less efficient than current PV cells. To compensate you just need lots of surface (leaves) which makes you stationary for practical r
Re:Efficiency is not really important (Score:4, Insightful)
1) What if I could sell you PV cells that cost 1% the $/Watt of traditional PV cells, but 1 acre of it only generated 100 Watts? Now you need an acre of land to power each 100 Watt light bulb.
2) What if I could sell you PV cells that cost 1% the $/Watt of traditional PV cells without taking up that much space, but they required 10 times as much maintenance after they were installed, perhaps even needing to be replaced every year or 6 months? You going to pay someone to keep reinstalling it?
3) What if I could sell you a bunch of super-cheap reflectors to focus the sunlight onto one tiny but expensive PV cell? If my parents, or possibly even my neighbors, had one of these when I was a pre-teen, I'll bet I would've been up on the roof with a big mirror or lens playing around with my nifty "fire ray", and I would not have been alone in trying that. And what about pine trees? I wouldn't want pine needles bursting into flame as they fall through the concentrator on my roof, so the concentrators would need some sort of enclosure, which limits their size, and thus their power.
I might be able to come up with other scenarios if I give it more thought, but I think you get the point. The PV cell's $/Watt cost is not the only cost to consider.
Parent
Re:Efficiency is not really important (Score:5, Interesting)
1) The cost of the land would have to be taken in to account
2) The cost of maintenance would be taken in to account
3) The cost of legal fees and vet bills for treating spontaniously combusted neigbours pets would be taken in to account.
The parent's point still holds, the important factor is the total cost of a PV system (installation, land space, maintenance and enclosure costs included) divided by the power it produces.
Parent
Re: (Score:3, Informative)
Both of your examples would have the same $/watt ratio, and yes, they're equivalent in that sense.
Re:Efficiency is not really important (Score:5, Insightful)
Many improvements in efficiency are through more expensive processing etc resulting in more expensive PV. The World Solar Race favours the team with the best efficiency, even if that costs hundreds of thousands of dollars. Much of the PV research is geared towards efficiency and this is the measure by which they compete (eg. http://www.boeing.com/ids/news/2006/q4/061206b_nr. html [boeing.com]).
This focus is detremental from a practical position of solving the energy crisis. While the big research dollars are focussed on efficiency we will continue to have PV that has useless $/W. It is far more important to ignore efficiency and focus on $/W.
I won't use PV if it costs me $20,000 to fit a PV array. If I could fit a $2000 PV array we'd be talking. So what if that takes up 50 square metres of roof space instead of 5? Cheap stuff could even be made into roofing tiles. It is reducing the $/W that makes PV practical.
It is a real shame that Boeing will spend huge dollars to inflate their egos with high efficiency while more practical programs like http://masseynews.massey.ac.nz/2007/Press_Releases /04-04-07.html [massey.ac.nz] struggle.
Parent
Re:Efficiency is not really important (Score:4, Funny)
Gee! Wonder why!
Parent
current is a bogus measure (Score:3, Insightful)
Monty Python (Score:5, Funny)
Parent
60 is misleading (Score:5, Insightful)
The best solar cells today get about 13 watts / square foot. The toatl power available on a sunny day with near perpendicular light is 130-140 watts. So efficiency is near 10%. The best a new design can do is about 10-11 fold increase, not 60.
Re: (Score:3, Insightful)
Re:60 is misleading (Score:5, Insightful)
Parent
Is solar really green? (Score:3, Insightful)
Outdated canard (Score:5, Informative)
Instead I'll say: That may have been true once, but it isn't any more. It will become less and less true with time, as learning economies and economies of scale come into effect.
Parent
Re:Outdated canard (Score:5, Interesting)
The fact that you closed with an ad hominem barb leaves me doubtful. More referenced research and less willfully ignorant babble please.
Energy pay-back time and CO2 emissions of PV systems [wiley.com]
"energy pay-back time was found to be 25-3 years for present-day roof-top installations and 3-4 years for multi-megawatt, ground-mounted systems. [...] This leads to the conclusion that in the longer term grid-connected PV systems can contribute significantly to the mitigation of CO2 emissions."
(found by typing 'photovoltaic payback time' into google)
Parent
Re: (Score:3, Funny)
Re:Is solar really green? (Score:5, Informative)
Electric power delivered to me at home is about $0.10/kwHr. Solar panels are about $5/w for the panel or a bit less. Grid tie inverters are a bit under $1/w (at least in the low kilowatts range). It's a bit pricier if you want batteries and completely off-grid, but I'll assume a simple grid tie system designed to reduce your utility bill.
That means your solar panel needs to produce 60,000 wHr of electricity per watt to pay for itself, ie it needs to operate for 60k sunny hours. That's about 25 years or so, in a reasonably sunny mid-latitude climate. That's about the life of the solar panel.
Now, that only sort of answers how green they are. In terms of carbon budget, they probably come out ahead -- not all the cost of the solar panel pays for the energy to make it, there are other costs as well. In terms of total pollution, I don't really know -- there are some nasty chemicals involved, but I think the silicon industry in general is pretty good about disposal (I don't know details off hand, sorry). I don't think there are any subsidies on the manufacturing, just tax credits and such when you buy them, so I think I've fully accounted the costs.
So, overall, I'd guess they're marginally greener than the alternatives. Solar panel prices are falling rapidly, which means they're getting greener to make (at least if we assume manufacturing techniques aren't getting messier). I'd guess they start to come out clearly ahead in the next couple years.
Parent
Re:Is solar really green? (Score:4, Interesting)
When Mark Pinto of Applied Materials spoke at Stanford in EE380 two weeks ago, he said that the current energy payback time on their solar panels is two years, and they're trying to get that down to six months. Some of the fab steps borrowed from semiconductor processing, where the areas aren't so large, can be improved.
Parent
Myth. Solar has a VERY good energy payback (Score:5, Informative)
The energy payback peroid for various PV cell types are:
Crystal Silicon: 3.3 years [chem.uu.nl]
Multicrystal Si: 0.8 years [chem.uu.nl]
CIS: 0.4 years [chem.uu.nl]
To put that is perspective of EROI:
Photovoltaics (Si): 60:1 - 10:1 (based on above)
Wind: 60:1 [awea.org]
Coal(US average): 9:1 [eroei.com]
Nuclear (light water): 4:1 [eroei.com]
Oil (mid-east): 10:1 - 30:1 [eroei.com]
Oil (US): 3:1 or less [holon.se]
And that is keeping in mind that the lifespan of PV is calculated at 30 years, an arbitrary number picked to equalize it with the life of a coal or nuclear power plant, however are panel warranties are 20-30 years alone. There is no reason to believe that the average lifespan of a PV panel won't be 40-60 years or more.
Parent
Re:Myth. Solar has a VERY good energy payback (Score:5, Informative)
1. My previous post was about Energy return on Investment. In other words, how much energy must be invested to extract another amount of energy. Not economics. Different issue.
2. The economics of solar however, are based on many issues. One such issue is it is being done on an inefficient small scale, by small time installers. Your Solar system would use around $45,000 in PV panels. Toss in another $7,500 for inverters, racks, etc. So you end up with around $30,000 in labor and profit - rather steep (find another installer). However, PV is currently competitive with some electric rates. On a equipment basis PV can produce power at around 8 cents/kilowatt hour at current prices - the rest is up to labor rates.
3. The solar market is a supply limited market, which is pushing prices up. Right now world-wide demand is outstripping supply by ~30%. It is seriously keeping prices inflated. Blame capitalism. Right now PV manufactures can charge whatever they want. But as the supply catches up, you see things change in the next 5 years.
4. Technology and manufacturing advances are bringing down costs as we speak - the question is when that will reflect in prices.
5. It is also a question of economic externailities. The US invests HUGE resources in securing the middle-east region because it has a critical resource: oil. Some estimates of the Iraq war alone, bring the US cost to $2 trillion [64.233.167.104]. For the same amount we could have replaced 33% of our electric production with solar - proving free electricity in peripituitary.
Parent
Is this supposed to be a bad joke? (Score:5, Funny)
Besides the bad pun... you obviously have never used magnifying glasses on poor helpless insects...
Cost comparisons (Score:5, Interesting)
But it doesn't matter to me that some hydro-electric plant far from my house is making power at $0.02 per kWh, what matters to my economic reality is that my local power company charges just over $0.08 for the first dozen kWh delivered each day and then has a sliding scale that goes up to $0.36 kWh for increased amounts of power.
Before I installed solar panels a high percentage of my power was costing me that top rate. So the relevent economic calculation for me is the cost to install my panels divided by the expected number of kWh that they will generate across their lifetime. This number comes out at about $0.16 per kWh. So I'm better than breaking even now, and assuming that energy prices continue to rise, I'll do even better in years to come.
The final kicker in the equation is that I've switched to a time-of-use tariff so across the summer the power company will credit me with $0.209 for excess power that I generate in peak hours (between 1pm and 7pm), and $0.112 for partial-peak (10am-1pm + 7pm-9pm).
If I'd taken the capital that I used to install the panels and invested it instead, I'd have to maintain a >19% annual pre-tax rate of return to beat the panels. Possible, but extremely unlikely (especially with my stock-picking track record!).
Tag (Score:5, Funny)
Great (Score:5, Funny)
What a useless article.... (Score:4, Informative)
Just out of curiosity... (Score:3, Interesting)
Re: (Score:3, Informative)
For utility scale systems they seems to be more cost efficient than big arrays of solar cells. The downside is that they require direct solar radiation so they are very inefficient on a cloudy day.
Dumb question (Score:5, Interesting)
That's not news (Score:4, Informative)
This is news: http://www.abc.net.au/catalyst/stories/s1865651.h
Sliver cell solar technology. This was on Australian TV in March. Generating the same amount of power using a fraction of the silicon required today. Brilliant.
How does this work (Score:3, Interesting)
Let's say that the 3D panel has 10 times the surface area of a flat panel, with the same dimensions. It still receives the same 1400 W/sq m as a flat solar panel, so the amount of solar power going into each sq cm of the panel has to drop to 1/10. It seems to me that the 3D panel wouldn't produce any more power than the flat design.
So there has to be a second effect at work. Let's see if we can find a better article than the information-starved FA? this article [sciencedaily.com] claims that the efficiency is increased due to reflections, i.e. each photon has more than one chance of being caught by a PN junction. Ah.
I wonder if this would work on macro scale, by placing two panels at a 45 degree angle to the sun, and 90 degrees to each other, like this \
Re:Better then 5x improvement not possible.... (Score:5, Insightful)
The statement "60x the current" has almost no relation to the maximum theoretical conversion of sunlight efficiency. It completely leaves out the voltage problems inherrant in these 3d designs. The total output measured in watts or VA would be somehwat more comparable to your "20 percent efficient".
Learn some math before you post.
Parent
Re:Better then 5x improvement not possible.... (Score:4, Funny)
You must be new here.
Parent
Re:Bad math.. (Score:5, Informative)
Nobody claimed they produced 60 X the power. In DC circuits Volts X Amps = Watts. 60 times the current does not equal 60 times the power if the voltage is not the same. The article is very clear, the voltage is way down. They make no power claims. It's even implied that the voltage is near zero. These panels may be less effecient than the curent generation. They are working on raising the voltage. Good luck and I hope they come out with some power figures soon.
Parent
Re: (Score:3, Funny)
Stick it onto a transformer and make the sun blink.
There ya go!
Quite a bit more than 20% (Score:4, Informative)
JSL
Parent
Nice Try (Score:4, Informative)
Almost. The laws of thermodynamics dictate that you will never get more energy out of a system than you are putting in. The measurement that we're interested in is not the thermodynamic efficiency, but the "thermoeconomic" efficiency. ThermoEconomic Efficiency is the ratio of the cost of the energy in to the value of the energy out.
The 4KW heat pump you mention is only providing 10KW because it is sucking the extra 6+KW from the ground. The key is that you don't pay for that 6KW of ground energy, but you do get value from it. So, thermoeconomically the heat pump is running at 250% (10KW/4KW), but thermodynamically it is running at less than 100% (10KW/(4KW+6KW+friction)
Parent
Re:There's NO free lunch (Score:5, Insightful)
No. There is simply more power in the Earth's wind than we could harvest. Or, if you please, the current annual input of power into the atmosphere is greater than the total energy cost of human civilization, by a few orders of magnitude.
Remember: every single watt of solar power that reaches the ground winds up in the atmosphere as heat, the foundation of wind.
Also solar power cools the Earth's surface. Solar farms are envisioned as acres and acres of panels in the desert. That would turn a very hot spot into a very cold spot, changing the currents there, and thus affecting overall temperature distribution (ie, the wind).
If, and ONLY if, the solar panels were not only almost perfectly efficient, but also sucked energy from heat in the atmosphere.
Same sort of thing goes for tidal energy. If you collect enough, you are going to affect life in the ocean.
Tides are powered by the moon's gravity, bub. Sure you'll have an effect, but the tides are already affecting the moon's rotation.
There just ain't no free ride.
Depends on what you means as "free." Sure, the soup kitchen needs someone to pay for the soup, but the bums getting a hot meal get to enjoy someone else's largesse. Most of the power sources available to humanity work like that, including photovoltalic solar, fission, and hydroelectric.
Parent
Re:Upper limit (Score:3, Interesting)
Nice straw men. Hats off. (Score:3, Insightful)
Re: (Score:3, Interesting)
That's really not true (about wind). It's entirely conceivable that humans could use almost all available (near-ground) wind power, if we chose to make that our only power source. And long before we even get to harnessing 10% of the available wind power, you're going to see big changes, like climate shift, thanks to the reduced power of the winds.
Re: (Score:3, Insightful)
No, I think you've probably got that wrong.
They'd offer it to the power distribution and oil companies - probably on terms that guarantee a revenue stream well past the expiration of any patents on the technology. Why handle the messy details of dealing with the Great Unwashed one-on-one, when others