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New Solar Panel Design Traps More Light
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.
This is non-news. Multi-layered cells have been talked about forever, and haven't they all previously run into similar issues?
"...produce sixty times the current of traditional models" BS!!
Current solar cells are ~20% efficient... you can't do better then 100% obviously.
I'm tempted to say "Cripes, This Again," because it comes up in almost every discussion about solar cells.
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.
The op article was vague and didn't have the pretty picture the one below has:
o lar.htm
http://gtresearchnews.gatech.edu/newsrelease/3d-s
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.
Ok, I'm a solar cell expert. I've been buying and selling solar cells/panels for years and I also construct panels with 0.5V 2 to 6A single-crystal cells... Now, take it from me, it is IMPOSSIBLE to construct a solar cell that is 60 times more efficient... like these other people are saying, the voltage would have to be considerablly less for the current to be 60X higher... the reason being is that THERE ISN'T EVEN THAT MUCH LIGHT COMING FROM THE SUN!!!!!! There are already cells out there that surpass 35% to 40% efficiency so DOUBLE would be an enormous step, but even 4X the efficieny is impossible.
Sorry guys.
It's like a third grader's book report... Why don't we just get the water from the well... from GTRI's site
What if it were a quarter the price and half as efficient? Then you'd pay half as much to get a certain amount of power, but it would take twice as much material.
Again, learn basic math.
The tracking motors etc for the mirrors are the deal breaker.
The only number that matters is $/watt. If they're cheap but inefficient we just cover the whole roof. If we run out of roof there is plenty of space in the western US.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
None, really. However, the problem is that right now we're looking at cells which are more like twice as efficient, half the material, and ten times the cost.
Both of your examples would have the same $/watt ratio, and yes, they're equivalent in that sense.
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Current solar cells are ~20% efficient... you can't do better then 100% obviously.
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.
The truth shall set you free!
Actually there is a far better technology out there which does what you talk about.
Lloyd Energy have developed a solar system which stores thermal power in the form of heat in huge blocks of graphite. You can then get that heat out and convert it to energy. This has two uses - taking power at off peak rates and storing it, selling it back to the market when the spot price of electricity is high, and the other is to focus a series of mirrors on the graphite so that it heats up, storing the energy for use whenever you wish.
The issue with this system is that it's slightly more expensive, but it can be used profitably by selling back to the grid at peak times (when power sometimes costs up to $10 000/MWh in Australia).
This is one of those grand myths that the public just can't shake. Photovoltaic's have a very good energy return on investment (EROI).
The energy payback peroid for various PV cell types are:
Crystal Silicon: 3.3 years
Multicrystal Si: 0.8 years
CIS: 0.4 years
To put that is perspective of EROI:
Photovoltaics (Si): 60:1 - 10:1 (based on above)
Wind: 60:1
Coal(US average): 9:1
Nuclear (light water): 4:1
Oil (mid-east): 10:1 - 30:1
Oil (US): 3:1 or less
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.
Spectrolab has cells that are over 40% efficient. See here for more details.
JSL
Where's the news in a half finished project that doesn't deliver any benefits (so far) on existing technologies? Who was the fool that got suckered into producing an infomercial?
t m
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.
Why doesn't Perry think referring to cream cheese as cow fudge is funny?
This is called concentrating solar power (CSP). See e.g. http://en.wikipedia.org/wiki/Solar_thermal_energy
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.
Actually, this approach is a different one to the multi-layered aproach you are probably referring to.
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!
30 year old boat, at least 5 previous owners (has been on one of our club moorings for twenty years).. bought it for £700 two years ago... costs £110 a year for insurance, £100 a year for the mooring, £80 a year club membership... excluding amortized purchase cost, this costs me £40 a month for the months I keep the boat on the water.
This is Yatching on the cheap... so I get really annoyed when components cost silly money just because they're intended for boats... let's see now, "approved" LED running & anchor lights cost some £300 just for the light assembly... I made my own for £25 total... non-slip deck paint £50 a litre... made my own using clean sand mixed in with outdoor grade paint for just £10
Anti-fouling is just about the only thing I can't do myself as I have to use the approved products by law... costs about £20 a year (I get two years applications out of 1 litre)
Charts, instruments and safety gear also cost stupid money, but I do all my sailing on a river so only have to worry about bouyancy aids
Donald 'Duck' Dunn: We had a band powerful enough to turn goat piss into gasoline.
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)
When our name is on the back of your car, we're behind you all the way!
That's not what the comment you linked to said. It simply said to "maximize efficiency". Nowhere does it imply that the cell isn't as efficient as current flat plate technology is. Further, it stated that a hybrid cell using this technology (and some other one I don't know about) can get 60-70% efficiency, though the comment didn't cite anything to back that up.
As for the heat, why not just cyphon off some of the energy to power some cooling fans built into the frame of the panel? I don't know if it would work well enough, but I'm sure it would be at least somewhat effective.
"Growing old is inevitable; growing up is optional."
The typical warranties for panels say that they will produce within 80% of their rated power over 25 years. The main cause of the degradation is defects in the crystal structure of the silicon created by cosmic rays. There is a very strong after market for solar panels because they can be used where there is plenty of land, say at a dairy or ranch, where ground mounting is not a problem.
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I like your comparison of EROI. I recently calculated the relative burden on transportation infrastrcuture for solar and coal: On the other hand, installed silicon produces about 200 kWh per pound before it needs to be recycled while coal only produces about 1 kWh per pound for a one time use so there are additional substantial savings on the transportation infrastructure side with solar. here:http://mdsolar.blogspot.com/2007/01/saving-n
I'm assuming 42 lbs for a 250 Wp panel and a 25 year life. If the panels don't move far in the after market, then the solar number probably goes up.
The EROI for hydro is pretty high as can be seen from it's very low price.
Current solar cells are between 15% and 20% efficient in converting solar energy into electricity. It is obviously impossible to achieve more than 100% efficiency without violating conservation of energy. In addition a 100% conversion efficiency is impossible as that would violate the second law of thermodynamics. So basically there is a fundamental limit to how much you can reduce the cost of solar power by improving the efficiency alone. I have mentioned this before, but just look at solar heating equipment. A near perfectly black surface absorbing light to generate heat is pretty much the most efficient solar collector you can ever get. A dash of black paint will also for sure be cheaper than any solid state device to generate electricity. So unless you live in a very sunny and warm region of the earth ( i.e close to the equator) it will be more economical to use some black paint and water-filled pipes to heat your house than to use photovoltaic cells.