From Slashdot, something so obvious you wonder why nobody tried it before: arrange solar panels like tree leaves for better efficiency. See the story and graphs I’ve provided below.
13-Year-Old Uses Fibonacci Sequence For Solar Power Breakthrough
An anonymous reader tips news of 7th grader Aidan Dwyer, who used phyllotaxis — the way leaves are arranged on plant stems in nature — as inspiration to arrange an array of solar panels in a way that generates 20-50% more energy than a uniform, flat panel array. Aidan wrote:
“I designed and built my own test model, copying the Fibonacci pattern of an oak tree. I studied my results with the compass tool and figured out the branch angles. The pattern was about 137 degrees and the Fibonacci sequence was 2/5. Then I built a model using this pattern from PVC tubing. In place of leaves, I used PV solar panels hooked up in series that produced up to 1/2 volt, so the peak output of the model was 5 volts. The entire design copied the pattern of an oak tree as closely as possible. … The Fibonacci tree design performed better than the flat-panel model. The tree design made 20% more electricity and collected 2 1/2 more hours of sunlight during the day. But the most interesting results were in December, when the Sun was at its lowest point in the sky. The tree design made 50% more electricity, and the collection time of sunlight was up to 50% longer!”
His work earned him a Young Naturalist Award from the American Museum of Natural History and a provisional patent on the design.
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Good for him! Here’s the output graphs:
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Awesome! As always, we should imitate mother nature because she is the best example of how to do things properly …. with billions of year of experience why not follows?
Further to George Smith’s comment, there is obviously something else going on here. Compare the 2 plots for Tues 14th. Standard solar appears to give a higher output … why is this ? Also look at the shadow across the centre of the standard solar. Where do shadows fall during the rest of the day ?
I very much doubt any “breakthrough”, especially the Fibonacci obfuscation.
What’s amazing about trees is that they grow leaves all around them, even on the north side… and they are all well distributed in size. Maybe the wind might help in distributing the light equally throughout the plant, leaves moving and turning.
Tracking PV will certainly capture the maximum energy. The motion system don’t consume much and most likely would be cheaper than a tree like structure.
Jeff Carlson says:
August 19, 2011 at 8:00 am
> … a solar tracker is really the ideal but this is some great work from a 13 year old …
A solar tracker is ideal if money is no object but land area is. If you are looking for energy sources to compete with or feed the grid from a home installation, trackers may kill the economics.
I’ve dealt a little with the Alt-E store. Good company. They used to have more active trackers, now they only have one (call for price, they probably need to size it for you) and several passive trackers that I hadn’t seen before. Their cheapest model for arrays up to 67″x36″ is $829 and “produces 25-45% more power in the summer.” A 65″x39″ array is $500 or so. Spend an extra $500, get 100% more power. And that’s without considering maintaining the moving parts.
http://www.altestore.com/store/Solar-Panel-Mounts-Trackers/Passive-Solar-Panel-Trackers/Zomeworks-Utr-020-Universal-Solar-Tracker/p2290/
http://www.altestore.com/store/Solar-Panels/Kyocera-KD225GX-LPB-225W-20V-Solar-Panel/p8517/
Oh – let me add a comment from the AltE folks. (They’re one of the few places that tells you why you don’t want half of their stuff. They’re also good at telling you how to use the stuff you can use before you order it.)
Solar Panel Trackers
Although solar panel trackers are expensive, (several thousands of dollars) they can produce more power in a day than a fixed array as they “track” the sun’s path. Solar trackers are often used in water pumping applications to maximize daily production (30-40% improvement over static solar panel mounting). They are generally custom built and take one to three months to manufacturer. One drawback to trackers is that they are subject to failure, as is any mechanical device, and could possibly get stuck in one position until fixed. Trackers are best suited for a handy individual. Each manufacturer provides a sizing sheet according to the number of modules you have and the configuration. These sizing sheets are often found in the Product Documentation tab of each product’s specification page.
Steve Mosher @ur momisugly 11:18
Thanks for the link, Steve, to eiq. This parallel approach is sorely needed, and I wish I had known about them (if they were around) a couple of years ago when I was installing my system. The standard series installation approach is a huge drawback.
At 10:02 AM on 19 August, HankH had made a damned cogent observation:
Instead of offering an active array which has some sort of mechanism to continually re-orient the solar panels, what Dwyer had done was to devise a passive configuration. As a proof-of-concept measure, Dwyer’s work here really ought to be followed up by the creation and deployment of a “forest” of similar structures, up-scaled and set alongside conventional passive and active photovoltaic (PV) arrays of equal surface areas.
Part of the acquisition and maintenance cost of PV electricity generation is in the support structures upon which these panels depend to attain efficiency, particularly those structures which are designed to episodically or continually undergo re-orientation to achieve optimal angles of incidence with sunlight. If a “forest” of multiple Dwyer structures could be shown to yield a degree of cost-effectiveness comparable with such expensive actively-orienting solar arrays, this might well be worth pursuing.
Note that I am not an advocate of Earth-surface PV solar power generation as a replacement for (or even effective supplementation of) the more energy-dense modalities required to provide baseload power generation for an industrialized civilization. I quote from a 2009 essay by the late James P. Hogan (titled “Nuclear No-Contest“) on the subject of “Solar Dreaming.”
and:
In those areas where solar PV energy sources are economically advantageous, the implementation of Dwyer arrays would seem to be a useful alternative to the current engineering art, but it’s by no means any kind of panacea.
“”””” S Matthews says:
August 19, 2011 at 1:06 pm
George E Smith;
‘So deliberately building an array of solar cells, that are quite non-uniformly irradiated, is really a non starter. It is ok to have differnt illumination on different arrays; but ONLY if they are series connected. For any single array in a series stack, non-uniform irradiation sets a limit to the individual array size.’
Not if micro-inverters are used. In which case it doesnt matter if there is different illumination. “””””
And the added cost of these “micro-inverters” is ???
What is the inversion efficiency of these micro-inverters, over the full zero to maximum insolation range.
The purveyors of existing solar cell arrays also have access to the use of micro-inverters, I presume; so where does the tree approach gain an advantage ?
There’s almost always a way to design around the shortcomings of any approach. Nuclear powered aeroplanes were never too popular, because of the limited weight capability left over for carrying passengers or freight; Otherwise it seemed like a good idea.
So what fraction of the existing installed solar cell array base, is presently using micro-inverters to overcome the limitation of unequal illumination or conversion efficiency ?
Solar cell trees are a wonderful idea for a 13 year old kid. As a taxpayer, I wouldn’t support using them instead of existing, and effectively functioning commercial energy sources.
Series strings of rechargeable cells (battery supplies), have a problem related to unequal cell capacity.. Starting from a completely charged battery, on discharge, the cell with the lowest Amp Hour capacity, will discharge first, and its internal cell resistance will go sky high, as the normal chemistry ceases to function. If the battery continues to supply current to some load, the discharged cell, will become reverse biassed, and for some chemistrys such as lead acid (ordinary car batteries) the cell will begin to charge in reverse, until something or somebody disconnects the load, and puts the battery back on the charger to recharge it.
Well the discharged battery Voltage will be much lower than normal, because of the reverse charged cell(s) in the string, and they will have to be discharged completely till they reverse again, and begin to charge in the forward direction. All this time the good cells, will have been taking on charge, until the weakest of the remaining good cells, reaches its full capacity, at which time, its internal resistance will increase, due to the change in chemical reactions, once charging is complete: such as beginning to hydolize water for example. The charger will eventually shut off when the overVoltage reaches the set limit, and that will leave ther previously reversed cells not fully charged to their original (and weaker) capacity.
So on the next discharge cycle, the weaker cell, will be completely dishcarged even sooner, since it never fully charged on the previous cycle.. Well you see how the problem snowballs, until one cell spends about equal time charging in each direction, at which time the whole battery will effecvtively have zero capacity. This unbalance problem sets a limit to the number of cells you can charge and discharge as a series string.
And yes for the electronic circuit whizz kids, you can certainly disconnect all the cells, and individually recharge each of them using micro chargers for each cell, and your Voltage micro-regulators can disconnect the load, as soon as they detect the loaded Voltage dropping by about one cell Voltage, indicating a comletely flat cell.
Tucci78 says:
August 19, 2011 at 2:21 pm
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To scale prolly wouldn’t be very effective….. as you stated, keeping things clean is important …….. birds.
We’ve got a radio tower behind our building at work…… depending upon the season, they’ll gather on the tower and make a mess of anything underneath. We’ve a nice parking lot underneath it, we can’t use it from spring to fall…….. unless you want to wash your vehicle daily.
I found the variety of comments and explanations here very informative – this is what we read WUWT for! The physical performance of solar cells is so often taken for granted, just as the makers always talk of the ‘rated output’ of wind turbines, which they never, ever attain.
I hate to rain on the party, but the conclusion drawn by this study are erroneous.
The voltage of these photovoltaic devices are not an indication of the “energy” produced. If you simply attach your photovoltaic device to a voltmeter, no current flows. The voltage is under this condition is called the “open circuit voltage” or Voc.
Alternatively, you can simply short the leads of the photovoltaic device. In this case, the voltage between the leads will be zero, but the current will be large. Under this condition the current is call the “short circuit current” or Isc.
In both of the above cases the energy generated will be zero. That is because the power is given by the current times the voltage (P = V x I). In the first case V = Voc = 0. In the second case I = Isc = 0.
Another important point when it comes to measuring the voltage and the current of a photovoltaic device: The short circuit current, Isc, will be nearly proportional to the irradiance on the. If the device is designed to work at “1 sun” (1000 Watts of sunshine per square meter of surface area) then if you drop the irradiance to 0.8 suns, the Isc will drop to 0.8 times its one sun Isc. Or alternatively, if you increase the irradiance to 1.2 suns, the Isc will increase to 1.2 times its one sun Isc.
The open circuit voltage, Voc, which is what our young scientist is measuring, does not behave this way. It is NOT proportional to the irradiance. In fact, if you reduce the irradiance to the photovoltaic device down to a few percent of the of the one sun irradiance, the Voc will still be at about 95% of the one sun Voc. Consequetly, twisting the cells in different directions has very little effect on the Voc.
So how do you actually get power from the photovoltaic device? If you put a resistor between the leads, then current will flow through the resistor and there will be a voltage drop across the resistor. The voltage will be less than Voc, and the current will be less than Isc, but neither one of them will be zero. Multiply them together and you get the power (P = V x I). But the voltage and the current (and hence the power) that you get will depend on the value of the resistor. For any given irradiance, there is an ideal point, the “maximum power point,” or MPP. Chose a resistor such that the photovoltaic device operates at the MPP and then measure the current through the resistor and the voltage drop accross the resistor. These are referred to as Imax and Vmax.
If you connect two or more photovoltaic devices in series, each electron that passes through the wires must also pass through ALL of the photovoltaic devices. If the current cannot pass through one of the devices, it will not pass through any of them. Now, think of the photovoltaic devices as old fashioned turnstiles at the subway. For you to pass through, you need to drop a quarter in. If you put two turnstiles in a row (for some crazy reason) you would have to put a quarter into each one to get through. It doesn’t make any difference how may quarters are going into a particular turnstile. Instead, only the turnstile getting the fewest number of quarters determines how many would-be passengers get to ride the train.
The photons of light falling on the photovoltaic device are like the quarters, and the electrons passing down the wire are like the would-be train passengers trying to get through the turnstiles. The photovoltaic device with the fewest number of photons falling on it determines the number of electrons that get to flow (ie, the current).
The bottom line is that when you twist the photovoltaic devices around so they are not pointing at the sun, the current drops to nearly zero (very few quarters in the turnstile), but the voltage remains high. If you just measure the voltage you might say to yourself “Gee, direction makes very little differnce.” But if you measure the current you will see that the direction makes all the differnce in the world. The current will be near zero and the power will be near zero (P = V x I).
Best regards,
Tom Moriarty
http://climatesanity.wordpress.com/about/
Something like they’re doing for cellular towers? I realize the antennae on these trees aren’t the leaves but there’s folks already building steel trees economically so at least a structural start.
http://waynesword.palomar.edu/faketree.htm
Couldn’t he have modeled that? Why did he think it necessary to go out and actually build and test it?
How primitive! Almost like a latent denialist!
/sarc
Congrats to this fine scientific mind!
“Gary Krause says:
August 19, 2011 at 8:28 am
Nature spends millions of years evolving efficiencies. We just need to get past our selves.”
Nature has spent millions of years in nearly 100% failure, depending on how you look at at. Of all the species who have ever existed, 99.99999% of them aren’t around any more. Are the ones we have today better than the ones who came so many millions of years before? If you could resurrect an olld species, how do you know that it wouldn’t dominate?
Congratulations to Adrian, he is obviously a bright young man.
To those that fault him on his understanding of photovoltaic power, note that of his references at:
http://www.amnh.org/nationalcenter/youngnaturalistawards/2011/aidan.html
only one was concerned with photocells., Most were about phyllotaxis and Fibonacci numbers. He interest is obviously more in biology and mathematics.
As a past Science Fair judge for our local ASME chapter, IMO he has done extremely well for his age. Any mistakes that a 7th grader makes in his presentation (e.g. volts are not power) are the fault of his teachers. Why didn’t his teacher tell him that measuring voltage wasn’t the same as measuring power? Or that power generating equipment should be tested under load? Probably because what he was doing was way beyond his teacher’s understanding,.
The advantage of this, is that by in effect building up your using less actual ground space, in a situation where this is limited by availability or cost , that is a good idea .
I’m sorry, everyone seems impressed but I don’t get it, at all, perhaps someone smarter could spell it out for me. It would seem trivial to determine the optimal direction to point a cell for power capture, what is the point of facing cells in suboptimal directions? In fact, I don’t see the purpose of the ‘tree’ at all. How does an individual cell operate any differently because of it location in a ‘tree’.(except for of course those occasions where it is shaded by a higher branch). Would they really operate any differently if set out on the ground at the various angles?
Someone with patience and smarts please help me out! Thanks in advance.
Good that he has a liking for science projects.
If the Australian Government led by “There will be no carbon tax under the government I lead” Gillard hears about this a team of scientists sponsored by the taxpayers will create new green jobs studying this idea. They will of course need extra funding as problems are encountered with the “Model” tree.
By year end there should be at least 100 new green jobs created and a few million dollars invested in the scheme.
A brilliant idea especially for a 13 year old.
However, engineers can usually do better than nature.
Living things have extra requirements that man-made things don’t have to worry about. Trees have to grow and replace leaves, and compete with other trees and browsing animals. The leaves have to take in CO2 as well as sunlight.
A man made collector can track to face the sun.
We don’t have jet planes flapping their wings just because birds do that. And jet planes don’t have to come out of tiny eggs and reproduce and eat whatever they can find.
George E. Smith says:
August 19, 2011 at 3:36 pm
“So what fraction of the existing installed solar cell array base, is presently using micro-inverters to overcome the limitation of unequal illumination or conversion efficiency ?”
Micro inverters are becoming very popular in the U.S. Here in Germany we don’t use them for now, but the Americans love the ease of extending module by module and just connect them via 110V lines. I think it has to do with the subsidy regime in Germany; you have to apply for the subsidy for an installation of size X; and it has to be installed until deadline Y, otherwise you don’t get the current subsidy rate, guaranteed for 20 years, at the moment 25 or so Eurocents / kWh. Depending on the installed wattage, subsidies will be cut once or twice a year; reducing subsidies by 10 to 20% each year for the next calendar year. (only for new installations; the approved ones keep getting what they were promised).
So that highly bureaucratic system makes it extremely unattractive to extend an installation piecemeal.
America on the other hand works with tax breaks or tax credits (as far as I know), so it’s much more attractive to invest a little each year. Micro-inverters are ideal for that; added advantages are easy wiring, no performance degradation for a whole string of modules when one module fails, or one micro-inverter fails, or one of the modules in a string is in a shadow. You also have much lower voltages – traditionally you run a PV installation with a DC voltage of 800V or so; when you have one micro-inverter per module the voltage is much lower.
(I have no stake in micro inverter makers so if this sounds like an advertisement, apologies – just wanted to say why they are being developed)
I normally wouldn’t butt in on something like this, but I have recently judged a High School Science Fair (regional level in Florida) and was surprised and appalled at what some teachers or advisers had allowed to be carried all the way through to a project presentation.
I agree with the commenter that noted the fact that the tree design has more solar panels – by my count, almost twice as many – as the flat panel model. There does not seem to be any adjustment for this fact, so the claims of higher efficiency are not valid – irrespective of whether he is using voltage instead of amp/hours to determine energy produced.
That said, the idea was good and original and shows the ability to think outside the box, using advanced mathematical concepts. I wish his adviser had helped him/her refine the procedure for determining energy production and the comparison steps.
If solar panels could efficiently produce electricity at the light levels plants use to photosynthesize , using the plant/leaf model would make more sense–unfortunately, those solar panels haven’t been developed yet.
I would score this project high for originality and scientific thinking, but mark down for skewed results due to the two obvious errors.
Correction to my 3:43pm comment.
The 4th paragraph should say…
“In both of the above cases the energy generated will be zero. That is because the power is given by the current times the voltage (P = V x I). In the first case I = 0. In the second case V = 0.
They should use solar panels to cover the blades and structure of windmills.
sarc / off
Well done by the young lad.
Less well done by his mentors.
Even less well done by the judges that awarded a prize for this.
As others have noted;
There are clearly more cells in the tree (note the peak voltage, it would be equal if the number of cells was equal (assuming the same type of cell, they all look like Silicon in the photos))
Voltage output is not efficiency (you need to measure the current output under load)
This arrangement (once corrected to have the same number of cells) is actually LESS efficient. The current from the illuminated cells will pass through the “darker” cells and cause some IR heating. This is both lost electrical power and it reduces the solar to electrical conversion efficiency of the “active” cells.
All in all a good sign that a young lad is this interested, hopefully he will pursue engineering or real science and have good mentors.
Cheers, Kevin.
I just reread the original post and noticed the following;
“provisional patent on the design”
Well, just so you know this infers that a provisional “design” patent has been granted.
Just a quick lesson on patents, a design patent just means that somebody else cannot make something that “looks identical to your design”, for example if you make a vacuum cleaner with three fake unicorn horns sticking out of the left side and a fake rhinoceros horn sticking out of the top you can (I’m assuming that nobody thought up that combination yet) get a design patent on that. So that means that nobody else can ever make a vacuum with the same fake horn pattern and sell it to anybody. But somebody could make a vacuum cleaner with the fake unicorn horns on the top and the rhinoceros horn on the right side and sell it without infringing your design patent.
This is totally different than a utility patent (think Edison’s light bulb, the transistor, the microprocessor, etc. etc.). The utility patents are the VALUABLE ones that all the big companies sue/trade/sell/make millions over.
The sad truth is that there are quite a few SCAM (strong words but true) “patent attorneys” who will charge you a few thousand dollars to get you a design patent. The process is easy, you submit a sketch of your design, the patent office checks all the other sketches to make sure that your sketch doesn’t match any of the other sketches in their files and grants you a design patent. The fees charged by the government are a few hundred dollars (I might be off by a bit I haven’t checked lately) but the attorneys mark this up to make sure they make a tidy profit for handling the paper work.
I do hope that this young lad’s parents did not fall for this SCAM and part with a few thousand dollars. That would be a really sad outcome.
The real purpose of the design patent was to prevent somebody from making something that looks identical to your product but performs poorly and thereby makes a profit of off your better known “look”. The iconic shape of the classic Coke bottle is a good example of a design patent.
Disclaimer; I am not a patent attorney, but I do have some utility patents assigned to one of my employers.
Cheers, Kevin.