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:
Now that sounds like a job and research well done. Guess it doesn’t have to be done only in Ivory towers!
That is really cool.
Nice idea, but i think it will go the way of Solyndra – complicated structures are more expensive than simple ones, so the simple one wins in the marketplace (yes i know the solar market is distorted by subsidies, but within those conditions, technologies still compete against each other).
Now that’s cool.
It’s an interesting result, but I’m not sure the data presented support the conclusion of “20-50% more energy.” He measures voltage, not energy. Solar panels have to be loaded to their maximum power point (MPP) to get the most energy. The voltage x current is maximum at MPP, but voltage is well below the peak (open circuit) voltage.
With his design, each cell has a different angle to the sun. There may not be a well-defined MPP.
The point of PV arrays is to create energy. The measurements are for voltage. He’s demonstrated that a range of angles generates voltage for longer than a flat panel array with a single angle. He has not demonstrated any increase in energy harvest. There is reason to believe that the energy harvest from his array will be lower.
It is a good idea and great study.
In practice, I expect the cost of the structure would outweigh the increased output especially as panel costs continue to fall. And, it could be argued that some solar panel systems already mimic nature by tracking the sun – just like some plants.
Young, bright, minds unfettered by agendas and paradigms?
Excellent and congratulations to such a young and brilliant mind. Hope to see more good things come from our younger generations.
Oops, should have said that “The point of PV arrays is to harvest energy.” Energy can’t be created or destroyed.
Good for him.
I had always understood that to maximise the input energy, it was necessary for solar panels to be steered much the same way as a movable satelitte dish. Indeed, I believe that there are already mechanisms on the market which allow panels to be steered so as to track the movement of the sun.
Clever and cute, but the siting of the tree seems to be influenced by the house.
Also I count 10 panels on the house and at least sixteen on the tree. Sixty percent more panels might actually produce 20% more power.
“The pattern was about 137° and the Fibbonacci sequence was 2/5” is gibberish without context. Couldn’t you maximize generation even further with panels that track the direction of light and use low input, high efficiency motors to orient themselves (like sunflowers)?
Anyone who likes Fibonacci numbers has a promising future.
Very clever idea. Needs bigger panels that can work while partially shaded – trees do a good job of intercepting nearly all the sunlight.
BTW, a great place to watch a partial solar eclipse is from a tree. The leaves make a lot of pinhole cameras, and you can control the number and size by climbing up and down.
Not to be all hard-assed on a really AWESOME bit of work, but that ‘typical’ solar array in the picture really ought to be at the same height as the ‘tree’ solar array. Otherwise it will be hit by shadows significantly earlier than the ‘tree’ solar array.
OTOH, that picture may very well be only for display purposes and doesn’t reflect the actual experiment.
great work … for static arrays that may be the way to go … a solar tracker is really the ideal but this is some great work from a 13 year old …
Clever but what happens if the flat panel can be moved and trace the sun? This is only good for static installations?
I can see at least 16 panels on the “tree” and 10 panels on “control”… no wonder.
Simply brilliant. Well done Aidan.
Very interesting. When I bought panels on my house a couple of years ago it was like pulling teeth to get the contractors to do anything other than all panels on the same roof, at the same angle, facing the same direction. I wanted to add a couple more panels on perpindicular roof slopes, but they all insisted that they couldn’t do it because of limitations of how the inverter dealt with incoming load (couldn’t handle wide variance between the two circuits). Pretty frustrating and poor design, if true, although I never could ascertain whether it was a true design constraint or if they just had their “warranty” installation instructions they couldn’t deviate from.
One question about the teen’s experiment above: Is it just me, or does it look like the tree version has way more panels than the flat version? If so, was that taken into account?
The backing wall of the building has an off-white surface with a strong albedo. The “oak-leaf-like” solar panels appear as though they might benefit from this. The “linear” (flat) solar array appears not to benefit from the reflected light.
As an aside, the WSJ recently ran an article on “bottle trees” and if you search on that phrase you can find many hits. Blue is a preferred color – keeps evil spirits away. It was noted that some folks find such structures unattractive.
What a brilliant young man. It makes sense that nature is using its own type of fractal antenna since it is collecting electromagnetic radiation.
“A fractal antenna is an antenna that uses a fractal, self-similar design to maximize the length, or increase the perimeter (on inside sections or the outer structure), of material that can receive or transmit electromagnetic radiation within a given total surface area or volume.” http://en.wikipedia.org/wiki/Fractal_antenna
While it does make sense to me in principal, I wonder what effect (if any) the sunlight reflecting off the white paint in the picture above would have had on the experiment. The tree-arranged panels are closer to it than the traditionally arranged.
This really doesn’t seem like it should make that big of a difference, but it is hard to argue with data (as it should be).
A cute idea and well done for a 13 year old. Uses panels in a 3 dimensional tree-like rather than normal planar arrangement. But produces LESS power per panel as they are occasionally shaded by other panels and structure. So totally useless given that panal costs are the primary cost in PV installations and economics (the land area is almost free in comparison).
Nature spends millions of years evolving efficiencies. We just need to get past our selves.
Well done Adian, I don’t know the lads selection criteria, oak seems reasonable, but what of other plants that are known to specifically seek the maximum solar input…..say a sunflower for example?
A clever lad! well done.
[sarc on] Now, all we need to do is make the Sun shine at night and solar electric power would be useful. [sarc off]
Richard
In the picture I see the tree cells next to a white wall, so some reflected light may benefit the design, especially when the sun is off of the optimum angle. Where as the conventional arrangement , tilted 45 degrees will not benefit from the wall reflections.
There must be more to the experiment than this.
Great idea.
I’m sure it’s been tried, but wouldn’t panels that rotate with the sun and self-correct their angles work even better? I understand it would consume energy, and I’m sure it’s been thought of before.
Just another non-scientist thinking out loud.
I’m going to contest the idea that any design that mimics nature is automatically superior. I’m not prepared to argue in depth, but it seems to me to put limits on the imagination.
This is what is known as thinking outside the box.
In middle 90s I designed a sun tracking solar panel system for the camper of a friend of mine. It worked great for getting the most energy from the panel even if the panel was partially shaded by trees. I remember that I get the best results by moving quickly the panel every 30-40 minutes and putting the system to low power for the rest of time. That because the panel had a quasi-co-sinusoidal response as function of the angle from its normal (it was probably a lambertian emission law pattern).
For that reason I really wonder seeing the discontinuities at the top of the “Standard” (I guess it’s the flat) panel response.
Does he tested the system in the place of the photo?
If he did it, that’s not really the right place to get the maximum from your solar panels, I can see many shades from the leaves and branches of the trees in front of the house.
One more, the efficiency should be measured as function of the produced power along the time, not as the voltage at the solar panel terminals.
If that measured voltages were taken without any load attached to the solar panels, those graph are meaningless, because many solar cells produce the nominal voltages with a little light on them but as you connect a small load the voltage drops quickly.
Yes, there may be some minor issues with the design — I did a biology experiment in 10th grade that was way lame compared to how I would design it today. That’s not a reason to knock it down but to ask questions and design a better follow-up experiment. Two specific comments:
1. Yes, it looks like there are more panels, but if that were the case the peak volts should go higher than 5. So maybe this is an illustration.
2. Tracking arrays are more efficient than static arrays. The problem is not the energy cost but the maintenance costs. Remember those wind farms Anthony posted about where 25% of the windmills are out of service at any give time due to maintenance needs? And I’ve seen the same thing.
3. Flat panels will probably be cheaper to install than trees, and land is cheap (for the sake of argument) but you’re forgetting about maintenance again. Didn’t Anthony post photos from a German solar plant where the ground was overgrown with weeds? Yes, here it is,
http://wattsupwiththat.com/2011/07/05/solar-showdown-weeds-vs-silicon/
I can definitely think of times and places where an efficient small footprint “tree” would be better in the long run than a large flat static or tracking array.
If we want cheapness and efficiency, how about growing trees and then burning them in wood stoves: free fuel, good exercise and a zero-sum CO2 game. Forget solar panels entirely. Go Green. Nature is way ahead of us.
Should be a business plan here, perfect for Africa, if not New York City.
Congrats to the kid! He followed through with an idea. We all have ideas, and the world would be a better place if we put many of them into practice, getting better with time. Must be satisfying to him and his family. If Gore/Suzuki/Hansen followed through with their low-impact lifestyle they say is so necessary (for others) we’d be impressed also. Let’s let them take a lesson from this story: follow-through and see what happens.
richard verney says:
August 19, 2011 at 7:51 am
“I had always understood that to maximise the input energy, it was necessary for solar panels to be steered much the same way as a movable satelitte dish. Indeed, I believe that there are already mechanisms on the market which allow panels to be steered so as to track the movement of the sun.”
Yes indeed, but no more used in many new installations – panels have become so cheap that the cost of the mechanics for the tracker becomes uneconomic. Just add more panels instead of buying an expensive tracker.
its usually the obvious simple that works unfortunately as an afterthought LOL well done lad
I give young Mr. Dwyer much credit for an innovative experiment and for putting much thought into this. However, his results do not add up for me.
1. From the pictures, it appears that there are 10 solar cells in the standard array, but a larger number in the tree. It’s possible that there are more solar cells in the standard array which are on the “far side” of the gabled roof in the picture, but if so they would be shaded and fairly useless as far as collecting solar energy.
2. The standard array appears to be angled at 45 degrees to the horizon. If the location is at 40 degrees N latitude — just a guess — then it makes sense that it performs very poorly in December. The array should be significantly more vertical.
The combination of these 2 factors can explain the fact that the peak voltage from the standard array never gets as large as that from the tree arrangement. It makes sense that the tree arrangement can collect energy for a longer period of time, due to its diversity of orientations. And this shows in the comparison of voltage traces. But a properly situated linear array should generate a larger voltage when all of its panels are at an optimum orientation relative to the sun, and this is not the case in his results.
Again, congratulations to Mr. Dwyer. It is indeed a valuable insight to look at how Nature has evolved its creations, and to learn what works best in a practical, non-ideal environment. In this case, however, I don’t think that a tree design will improve on a (properly oriented) linear array as far as average power is concerned. However, the idea of multiple orientations can be used to extend the duration of large energy collection. [At a cost in either average power or number of cells.]
fine Job, young man!!!
Like others have said, no load voltage readings are meaningless. My 5,000 watt PV system tries to start every morning before sunrise, for the panel voltage rises over 250V as soon as there is some light in the sky. It quickly shuts down and tries again in 10 minutes. This may happen 3 or 4 times before the system has enough light to produce at least 75 watts.
In addition, shaded panels drag down the performance of the others in the string. That would mean that all of the “leaves” on the solar tree would have to be independent, which would be a wiring nightmare.
I give the young man a lot of credit for being creative, however.
The whole idea is completely stupid – even for a kid. When building complex structures for the mere purpose of holding some solar panels into the sunlight is an option, you do it right and let the panels track the sun. You don’t build an artificial tree and let half your panels face north (not even if there is a white wall right behind you). Leafs don’t cost much for the tree – and they work to some extend even when they’re lit from behind. Unless solar panels drop to a few cent/squarefoot and become semi-transparent and/or unless the structure of a rooftop isn’t already there and paid for anyway, this won’t fly.
I really can’t undertstand how he managed to get started without a huge grant. 😉
Sorry but I don’t buy it.
Trees aren’t designed just to catch sunlight – they have to compete with other plants to get at light, produce visible flowers for reproduction, conserve water and absorb CO2 – and they can’t do it from consistently flat surfaces like roofs.
A structure designed purely for collecting sunlight would be far more efficient that something like this.
A thought. Photosynthesis is efficient enough that most plants don’t do much to track the sun (with light hitting the leaf surface at less than perpendicular angles. They get enough light by remaining stationary and taking in both the direct rays of the moving sun and the light reflected from the atmosphere. That is why leaves face in all directions around the plant. Notice that a tree growing out in a field alone in the sun doesn’t favor the south (in the Northern Hemisphere), it grows symmetrically. Solar panels just aren’t efficient enough to get away with the same system.
This “work earned him a Young Naturalist Award from the American Museum of Natural History,” did it?
An engineering approach like this has anything to do with being a “Naturalist“?
Well done, the lad did good!
But I would comment that a trees leaves are not just designed to capture the sun, but also to restrict surface area and reduce evapo-transpiration etc – so, not exactly a direct ‘design’ comparison IMHO. And of course, the average tree has a fairly dense canopy arrangement to capture as much light as possible. As others have commented the design also requires more intricasies and indeed strength to provide the support to the panels, etc. – so clearly design as a function of cost and productivity is a major part of the equation!
Robert F;
‘In addition, shaded panels drag down the performance of the others in the string. That would mean that all of the “leaves” on the solar tree would have to be independent, which would be a wiring nightmare.’
Maybe not that bad with micro-inverters. See :
http://www.exeltech.com/pvacproduct.htm
Wouldn’t a “tree” installation have a higher profile, air resistance-wise, than a conventional array? One good storm might bring the whole setup crashing down. Scaling it up to standard PV array sizes would also be problematic; the support structure would have to be more elaborate to handle the weight.
By definition, in a FIbonacci sequence, a particular term is the sum of the two preceding terms, so what does he mean when he says that “the Fibonacci sequence is 2/5”?
There are 16 panels on the tree, 10 on the front plane surface and 6 on the back of the plane.
This to me is not proper. All 16 should have been on the same, sun facing plane.
Everyone knows panels work best when the sun is at a normal vector to the panel. You can do the trig to find out the solar exposed area. Given my understanding of trig, the only way he could generate more in the tree was to put the 6 panels on the shady side.
I count 20 PV cells on the tree as compared to 10 on the flat panel. However, in the original article it is stated:
From this I must assume that the photograph of the experiment isn’t an accurate representation of the full experiment.
While some point out the light colored wall as a confounding variable in the experiment, I don’t see it that way. The traditional angled array of solar cells doesn’t benefit from the backscattered light from the wall whereas the tree array does. The fact that the angled array is lower than the tree and sees shorter exposure to the sun in comparison to the tree is actually a fairly accurate model. Many traditional solar arrays are on the ground below what would be the tree line.
What I get out of this is the solar array arranged in a Fibonacci sequence is able to capture and utilize more indirect light than a flat array and is less orientation dependent. Placing solar panels on a structure that raises the PV cells higher off the ground will result in exposure to the sun and backscattered light for a longer period of the day. I also imagine that using a tree style structure with a Fibonacci design allows for a greater density of PV cells for a given area of land.
Anyway, my conclusion is take some grant money away from the “Team” and give it to this kid. It would be money better spent as this kid is thinking out of the box – something we need more of in science today.
It’s nothing new, here’s some that have been installed and working over a year, there are a few different designs in Sevilla
http://www.losbermejales.org/page/5/
Edison, Bell, (Both Alexander and later, Larry)the Wright Bros., Jobs and Gates, all started somewhere. Good job, laddie!
You never know…
Wonderful to see such enterprising and intelligent science done by a 7th grader in th ebackyard. Bravo!
Idiot.
REPLY: No relation – Anthony
Obviously, Anthony, you are well behind the ball on AGW – NEWSFLASH – Dire Warning for the planet!
NASA report says space aliens could invade earth to stop global warming
Seriously, you can’t make this stuff up!
I think a 2/5 Fibonacci sequence begins with 2, 5, 7, 12…
Aidan says: “I designed and built my own test model, copying the Fibonacci pattern of an oak tree.”
Personally, I would have used this as my test model.
DirkH says:
August 19, 2011 at 7:43 am
Nice idea, but i think it will go the way of Solyndra – complicated structures are more expensive than simple ones, so the simple one wins in the marketplace…
——–
Were it that simple… I have vertigo, so I would have to pay for someone to install flat panels on my roof. OTOH I have a backyard that is clear of shadows, and experience of flat-pack furniture.
Well far be it from me to get critical of an inquisitive 7th grader; I was one myself, I think.
Mother nature does some strangely optimal things at times. When some plants, send that very first green probe up out of the soil towards the sunlight, it is often true that the very common rounded end of that light probe, conforms to one of the Compound Parabolic Concentrator shapes, where light can enter from a wide range of angles, into the refractive medium, and is thence trapped by Total Internal Reflection, and light piped down to where the rest of the plant is, so the plant is solar powered right from its very first look at daylight. The branch and foliage structure of conifer forests is known to be quite efficient at light trapping. Pine forests tend to look dark from above, because sunlight can get down between the trees, but is largely prevented from reflecting back out. This is part of the reason that pine forests are among the few, that can grow in far northern environments.
Some species of shrimp or other lobster like creatures, have eyes that are also CPC geometries for efficient light collection.
However, one of the limiting efficiency factors of solar cell arrays, is uniformity of illumination; and/or local cell conversion efficiency.
Solar panels consist of large areas of parallel connected semiconductor junctions; and then series connection of such parallel arrays. Well in a parallel array of photo-Voltaic junctions, the cells that generate the highest Voltage, will tend to forward bias cells with lower illumination or efficiency, causing them to conduct currents shunting energy away from the load. The exact same problem was encountered by companies such as Westinghouse, when they first tried to make high powered rectifier diodes for power engineering. Westinghouse tried to make a single semiconductor junction diode, out of a two or three inch silicon wafer to make a several hundred or thousand Amp rectifier. Well local wafer defects acted as shunt paths, and such rectifiers tended to burn themselves up at local hotspots.
Lestert C Hogan at Motorola discovered that they could make a good silicon diode, up to about a maximum of 18 Amp forward current (peak). In fact they could make millions of them. But they tended to have different forward Voltages at any forward current. So Motorola sorted the diodes by forward Voltage at several differnt currents, and then they assembled parallel arrays of 18 Amp diodes, to make a high current diode “module”. Very small current matching interconnect resistances, balanced the current through the parallel diodes, and Motorola was able to take over the high power rectifier business. Those same 18 Amp diodes, are to this day in just about every automobile Alternator, made anywhere on the planet.
Series connected devices have the opposite problem; the current tends to be dictated by thw weakest cell in a series string. It affects automobile battery design, and is a significant proble for those with electric car wheels turning in their brains.
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.
When the shadow each other like leaves on a tree, or trees in a forest, then the efficiency falls significantly.
A big problem with these very large solar farms, is that the arrays of panels have to be spaced apart so that no panel ever shadows another at any tiome of the day or year. It is easy to show that you never get better collection efficiency, than simply laying the panels flat, and covering ALL of the available land area that way. Of course, that requires more solar cells, so it is not necessarily the lowest cost approach. Well it likely is, if they apply taxes on the land area, the same way they would if you grew corn on it, or used it for any other kind of business.
Solar cell farmers, are living in a dream world, if they think their land use shouldn’t be taxed just like any other land use is. Which is not to say, I am in favor of land use taxes; I’m not, but if you are going to charge real estate taxes on land used for a garage, or hamburger joint; then the same taxes should apply to solar cell farms. But I’d rather see the taxes eliminated, and let people use their land for what they want.
But back to our seventh grader; keep thinking and tinkering young fellow;you’ll go far someday.
Solar engineering so simple, a 13yr old could do it.
When the aliens see the widespread application of this level of technology, they’ll know they’re messin’ with the wrong folks, and they’ll head for the hills! (invisibly, of course)
Now, the not-invented-here folks will surely be blasting this kid’s research, since he’s a) not affiliated with their university, and b) he’s not a solar scientist. I fully expect the Team to discredit him promptly over at RealClimate, for those, and other reasons. No grant money in it for ’em.
…but for me? Aidan Dwyer? YOU DA MAN!!
–the only downside to this is coming up with efficient manufacturing and installation. Maybe someone will figure out a way to “grow” the panels, as in stereo lithography?
George E. Smith
August 19, 2011 at 10:44 am
Thanks George, you answered some questions I was pondering.
George E. Smith: “It is easy to show that you never get better collection efficiency, than simply laying the panels flat, and covering ALL of the available land area that way. ”
I have a cruising sailboat where the only source of electricity to charge the batteries is from solar cells. Currently, I have mounted them flat, but have always wondered if there was a more optimal configuration. When attached to the mooring, the sailboat is constantly changing directions as the wind shifts. A tracking solar array would not work and physical simplicity is required.
This kid did get me wondering about a 3-D spiral mounted around the mast when not actively sailing.
Friends of mine. solar in parallel. pretty cool.
http://eiqenergy.com/
http://eiqenergy.com/parallel_solar/index.php
Two things –
1) This experiment has a lot of potential issues with it that people more experienced in engineering, electronics, and solar voltaics can (and have) pointed out.
2) Aidan Dwyer was 13 YEARS OLD and put this together!!! This absolutely ROCKS!! Aidan, I hope you get into engineering of some sort and start developing he kick-ass inventions that are going to blow our minds for the next 30 years! Keep on keeping on!
Seriously, if Aidan came to me, I would put some money to help him further develop and test this concept. If it pans out and we could do some business planning and development, I would invest in him to help him start a company to create and market these solar panel trees. They wouldn’t become solutions to the nation’s energy needs, but I bet that they could catch on in smaller, individual markets for those who want solar power but don’t want (or can’t fit) traditional solar panels.
Mega kudos to Aidan!!
There is an optimal angle for fixed arrays, such as this, in order to collect maximum energy – it obviously orients the solar panel such that it receives the most intense solar radiation during
the day. Any other angle collects less energy, therefore unless all of the panels are oriented
at the optimal angle, the energy harvest of the array will of necessity be less. The panels should be pointed due south. For an array of unchanging elevation, max yearly harvest obtained with an
elevation angle equal to 90 degrees minus one’s latitude. Changing elevation to match the Sun’s path doesn’t result is greatly increased harvest. Certainly nowhere near 30%. Perhaps 10%.
Trying to orient panels in the fashion shown here would result in extremely complicated mounting
apparatus and would be unsuitable for roof mounting, by far the most common method.
ideally what you would do is minaturize the cells and put them on a flexible substrate in the shape of leaves, no more ugly solar. hehe.
Color me skeptical. I find it very difficult to believe that the same number of solar cells mounted on a solar tracking system would not provide much more energy. Maybe compared to a fixed mounting system he can improve efficiency, although I doubt even that.
As others have noted Volts ain’t Power…
Obvious nonsense, for many reasons listed above. The kid does write surprisingly well, though, better than most adults. On the other hand, I’ll bet he doesn’t write better than his parents.
http://www.amnh.org/nationalcenter/youngnaturalistawards/2011/aidan.html
FAIL!
On the comments about the tree having more panels than the house…
Looking closely at the tree, it appears to have a total of 20 panels.
One poster has already surmised the house had 10 panels on the other-side of its roof for a total of 20. Which would then match the total number on the tree. Thus, no discrepancy in the numbers.
However, having solar panels on a roof facing away from the sun, is a whole different matter as to the validity of the results. Additionally, as others have very correctly pointed out, measured voltage without a load does not indicate the amount of power produced.
Warmista: “Was this research peer reviewed?”
Sceptic: “Why, yes it was! By 13 year olds, just like the UN-IPCC reports!”
Kuddos to this Kiddoo!
A simple hypothesis was tested by a simple experiment and the data and analysis were openly published.for critique and replication. The experimental data showed real promise and the hypothesis deserves further, more detailed testing to determine maximum feasibility and limitations. Well Done, Young Man!
I sure hope Aidan Dwyer chooses engineering as his primary career interest! We need lots more like him, out here in the engineering world…..
Oh, COME ON!! Click the FREAKIN’ LINK!!!!!
“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.”
This statement would indicate only 10 panels for the simulated tree.
Unfortunately, many solar panels do not work if all of them are not gaining energy. Shadows can kill. The shadowed units may become where the collected energy goes rather than to the system. It may have a lot to do with the wiring, also, and this may have been improved. On larger panels, a hand held over it can be enough to significantly interfere with performance.
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.
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 @ 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
=======================================
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.
And as others and you have gotten it wrong. Clearly in the text (if you bothered to click the link)
“The second model was a flat-panel array that was mounted at 45 degrees. It had the same type and number of PV solar panels as the tree design, and the same peak voltage.”
There are 10 cells on the back of the flat panel assembly, since about half the cells on the tree face the rear as well.
C’mon Y’all! The kid is 13! He did well. Most of you ‘critics’ didn’t even have a Playboy hid under your bed yet, let alone started thinking about mathematic series and solar cell arrays.
HankH says:
August 19, 2011 at 3:45 pm (Edit)
steven mosher says:
August 19, 2011 at 11:31 am
ideally what you would do is minaturize the cells and put them on a flexible substrate in the shape of leaves, no more ugly solar. hehe.
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.
####
yes. I saw one in santa rosa. Ugly looking fake tree.
But you can well imagine an artifical tree with solar leaves that capture light and C02 fixing leaves,
and a camera/zapper combo to discourage fido, all mesh networked, with little nests for surviellence micro planes that look like birds.
and apples
Great idea for a study by a youngster – but I really hope it wasn’t conducted as sited in the photo. I haven’t read a lot of the comments, but aside from issues noted of elevation and albedo from the house, it’s pretty clear that there are shade issues from nearby trees and with such tiny solar panels, the shade from a branch can wipe out collection from several of the panels.
Also, others noted that it looks like there are more panels on the ‘tree’ but I suspect that the flat panel array only clearly shows one side, and that the opposite side is on a triangle in effect between the side easily seen, the horizontal base, and a back side for the third side of the triangle… with a set of matching panels on that opposite side of the triangle. If so, that makes the siting next to the house all the more problematic.
We’d need better photos or a diagram or something to be able to tell, along with info about where the rig was actually sited for the experiment – and assurrances that there were no shading or other confounding factors.
The classical phyllotaxis pattern on a planar sunflower model is maximised when the angle between successive seed formation is 137.5 degrees or so. One formula suggests that the classic angle is the golden angle, γ = 2π(1 – 1/Φ), where Φ is the golden ratio. However, plots of patterns show that small variations in the angle, as little as 0.2 degrees, soon lead to loss of parastichy, see http://algorithmicbotany.org/papers/abop/abop-ch4.pdf Parastichy and chirality are terms related to the presence of spiral-like patterns between the dots, some which curve to the left and some to the right, classically related by one of the Fibonacci series. The series starting 0,1,1,2,3,5,8,13,21,34….each number being the sum of the pair before, is but one Fibonacci series, albiet the most commonly quoted. Thus, when the correct divergence angle is used on a planar example, the count of spirals is often like 5 to the left and 8 to the right. For larger variations in the divergence angle, rather different patterns are generated, see http://www.flickr.com/photos/twak/3115930730/
It is unclear in my reading how there can be a transition from an 8:5 pattern to a 13:8 pattern. Yet sunflowers can be observed with each, on the same plant. It seems that there is a disruption to the nicety when a transform happens and one can have trouble tracing the spirals, some of which have discontinuities.
It has been said by some (e.g. the late John Rouse, a friend from Physics Dept of Melbourne University) that the pattern, applied to a column of leaves on a stem rather than to a planar pattern akin to the sunflower, maximises the probability of light hitting leaves and so allows better photosynthesis. (Think of a palm tree and the scars left after leaf fall). This is OK if you look along the line of the stem – fewer leaves seem to be blocked to view by ones above. However, the prettiness falls apart when the sun is not axial with the stem. The theory is nice, but not adequate to explain the reality of Nature.
Further complications arise when the geometry changes to quasi-conical, as on a strawberry, or quasi-cylindrical, as on a pineapple. The Fibonacci ratios will often hold, but it is harder to determine a natural advantage in the pattern. By extension, it is hard to determine any natural advantage in the apparatus for solar collectors in the article. If I had my druthers, I’d model on this vegetable, a Brassica romanesque. http://www.fourmilab.ch/images/Romanesco/
Aidan Dwyer deserves high praise for lateral thinking with the solar collector, but maybe the lesson is that sexy discoveries in science can be romanticised beyond the level nature intended.
Dirk H says:
Nice idea, but i think it will go the way of Solyndra – complicated structures are more expensive than simple ones
============================================================================
Heh: why make a structure? Just grow one, ie: use the natural structures—-trees—with PVPs replacing leaves. Now there’s something for gengineering researchers to get their teeth into—to save the world.
A new acronym: “RTFL” == Read The Flippin’ Link!
So many s-righteous strawman putdowns.
Reasons for mounting a strawman argument:
1) Deliberate distraction
2) Misunderstanding through superficial reading
3) Misunderstanding through lack of background
4) Misunderstanding through lack of intelligence
and, featured prominently here:
5) Laziness — can’t be bothered to read the actual material.
Ugh.
Wow, someone looked into nature instead of just sitting down and reading about it.
This guy doesn’t need University – he’d be teaching his teachers.
Good for him. I hope he makes some money from it.
George E Smith;
‘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 ?’
In turn;
Cost is now approx similar to string inverters and dropping, at least for residential PV.
Inversion efficiency probably a percent or two less, but compensated for by optimizing the harvesting for each panel individually.
Tree? I just made the comment that the simpler wiring with micro-inverters makes the tree approach a little more practical that it would have been otherwise.
Fraction of base? Tiny. Mainly because the micro-inverters have only recently come good (price, performance). We will see an explosion of them over the next year or so.
Check out Enphase or Enecsys.
See http://www.efficientenergy.net/p/102149.htm
Ryan says:
August 19, 2011 at 4:16 pm
The optimal direction for a solar cell is indeed trivial – “normal” to the Sun. (Normal is a confusing physics/geometry term. In this case, it means the Sun’s rays are at 90° to any line drawn on the solar panel.) It can be off by 10 or 20 degrees and not have a big impact on power output.
The catch is, as I noted in a comment yesterday, it’s really expensive to maintain that angle as the Sun moves across the sky. In fact, if you try a compromise like aiming the solar panel at the Sun’s highest point at the beginning of spring or fall, then the panel only sees sunlight for 12 hours in the summer. Repositioning it every season make sense for a homeowner, matching orientation to power needs and storage make more sense, but that’s a whole different topic.
Suppose you had two panels and aimed one somewhat to the east and the other somewhat to the west. That way you’d get better power generation in the morning and in the evening, especially in the summer. Good deal, perhaps. Suppose you covered a dome with solar cells. That could work out pretty well on the equator, though the cells pointing due north or south would be shaded six months of each year. A dome at the north pole would have all the cells dark six months of the year, and the cells on top wouldn’t get much light any time.
Basically, the goal here was to fix in place cells in orientations to provide more hours of power generation. In particular, how do patterns from natural solar collectors compare with typical patterns? The goal was not to maximize power generation, especially with expensive things like solar trackers. It was a goal to provide more power (unfortunately, measured as voltage) than a fixed flat array.
Several of the comments in the thread talk about how to combine the output of solar cells. That turns out to be a challenging task in its own right. Most of what I have to say about that has been said, I might cover the rest later.
jaymam says:
August 19, 2011 at 4:41 pm
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.
Fair enough, but birds have been around for 100 million years and still will be around after jet engines are long forgotten.
Well done Aidan. Teenagers are a resource of immense intellectual creativity, which in our politically correct cosseted education system goes largely to waste. Teenage brilliance in the classroom often illicits jealousy from an intellectually inferior teacher and resultant bullying and abuse, such talent seen as a threat to the sociobiological primate heirarchy of the classroom.
WE DONT NEED NO EJOOKAYSHUN!!! WE DONT NEED NO FORT KONTROL!
Somehow in past ages young teenagers seemed much more free to excercise creativity at a professional level. Some examples of inventions by teenagers can be found at:
http://www.ideafinder.com/features/classact/young.htm
My apologies to Aidan, his text does indeed state;
“The second model was a flat-panel array that was mounted at 45 degrees. It had the same type and number of PV solar panels as the tree design, and the same peak voltage.”
However his graphs do not support his “same peak voltage” statement. Hence my statement about the number of cells.
I stand by my assertion that the open circuit voltage from an array of PV cells is not an accurate measurement of the “electricity” produced. I suspect that if the power delivered by both arrays was properly measured there would be no more total power produced by the tree.
His mentors and the award judges did him a disservice by letting him think that he has invented something that “generates 20-50% more energy than a uniform, flat panel array. “
Cheers, Kevin
Doug Proctor says:
August 19, 2011 at 9:00 am
“If we want cheapness and efficiency, how about growing trees and then burning them in wood stoves: free fuel, good exercise and a zero-sum CO2 game. Forget solar panels entirely. Go Green. Nature is way ahead of us.
Should be a business plan here, perfect for Africa, if not New York City.”
No good for Africa. We burned all of the trees for firewood long since. Not easy to establish new woodlands as with the trees gone the water doesn’t flow any more where it used to. Send some more aid money and with what little bit finds it way down to us we’ll be able to buy coal.
“”””” Geoff Sherrington says:
August 20, 2011 at 1:33 am
The classical phyllotaxis pattern on a planar sunflower model is maximised when the angle between successive seed formation is 137.5 degrees or so. One formula suggests that the classic angle is the golden angle, γ = 2π(1 – 1/Φ), where Φ is the golden ratio. However, plots of patterns show that small variations in the angle, as little as 0.2 degrees, soon lead to loss of parastichy, see http://algorithmicbotany.org/papers/abop/abop-ch4.pdf Parastichy and chirality are terms related to the presence of spiral-like patterns between the dots, some which curve to the left and some to the right, classically related by one of the Fibonacci series. “””””
Interesting Geoff that you should be talkng about the sunflower patterns, as a natural adaptation that presumably gives some advantage.
Is it not also true, that those very same sunflowers do in fact track the sun’s journey across the sky.
I’m looking at a couple of plants that are right outside my window. One of them is some non descript decorative yard tree, and the leaves I can see, which are low on the tree, ar very well shaded by the leaves above. I’m sure the upper ones are getting plenty of sunlight being at the top, and not shadowed. The other plant happens to be a white grape vine, and it has leaves densely all over it. So dense in fact that you almost can’t see any of the hanging bunches of grapes that are developing on the plant.
No it couldn’t possibly be, that plants may have other interets than just gathering the most sunlight. Grapes certainly do seem to want to protect the fruit from a lot of sun..
So some plants may arrange their leaves in ways, that ensure some sun gathering, but let’s not kid ourselves that that is the best possible energy gathering strategy. The sunflower clearly sees the avantage of scanning.
This Fibonacci tree is about on a par with “organic” farming. Without engineered crops, we likely would not all be starving; but you can be sure that the earth would have far fewer of us living on it.
Thanks for taking the time Ric, I’m not trying to pick apart a schoolboy’s science project, I still don’t understand why this is labeled a ‘breakthrough’ though even after thoroughly reading your post. You said that the “the goal here was to fix in place cells in orientations to provide more hours of power generation”. That problem is very simply solved with any number of arrangements superior to all cells facing the same way. (Duh, facing many directions gives you a better chance to be at least partially exposed to sunlight). Perhaps you could be more specific about what the fibonacci numbers and tree brings to the problem that any of the obvious arc/dome arrangements do not. I’m still struggling to understand any scientific mechanism as to how the cells operate any differently in fibonacci tree formation than if they were placed at the same angle/inclination on the ground. In short, I still don’t get it.
Always the skeptic I suppose. Oh well….
Sunflower technology already exists, http://www.greenandgoldenergy.com.au/ where the ‘cubes’ track the sun on both lat and long. Good old Aussie invention
Ryan says:
August 20, 2011 at 1:19 pm
Well, “breakthrough” was used by the person posting on Shashdot. My guess is he didn’t understand the limitations. The article he linked to did not use the word breakthrough, but did quote Dr. Seuss (The Lorax). I wouldn’t call it a breakthrough, just interesting, entertaining, and pretty well done for a teen whose age is a Fibonacci number.
I think Aiden is more interested in math and nature than generating solar power. This is a standard “pit” that many of us fall into and don’t always get out. I was about 13 when Martin Gardner wrote about Fibonacci numbers and the Golden Ratio in Scientific American (reprinted in a book, republished as http://www.amazon.com/Origami-Eleusis-Soma-Cube-Mathematical/dp/0521756103/ in 2008. Nope, the first book was published in 1961 when I was 10 or so.)
Natural occurences of Fibonacci numbers are intriguing, but can be explained by fairly simple processes. Still, plants do put them to pretty good use for things like intercepting sun or packing seeds. You’ll enjoy http://www.lhup.edu/~dsimanek/pseudo/fibonacc.htm and http://goldenratiomyth.weebly.com/phyllotaxis-the-fibonacci-sequence-in-nature.html . The latter says:
Unfortunately, the link to “Earlier” makes no mention of “the most irrational number” – even people writing about myths seem to get lost in the myths.
As for your last point, about how the “cells operate any differently in fibonacci tree formation than if they were placed at the same angle/inclination on the ground,” that brings up some significant issues that are discussed in other comments but no has really described the problems well. Nor will I, but I’ll get closer.
In a photovoltaic (PV) cell, sunlight knocks electrons on to the other side of an electrical barrier (barrier is a misleading word). Those electrons can be collected, run through something to extract their energy, and go back into the other side of the PV cell. (Well, the real electrons don’t go very far, as there’s a huge number of electrons that are moved. Think water hose – turn it on, water comes out instantly at the other end, but the water you added to the hose is still in the first few feet of the hose.)
The voltage produced is pretty small. You can put several cells together “in series” to get a higher voltage, but there’s a problem. If one of the cells is shaded, there are very few loose electrons in that cell, and that stops current through all of them. You can also put cells together “in parallel” where each cell provides its own current but the overall voltage is low. If the cells are a little different, then high voltage cells may block current from the low voltage cells. Also, illumination is important in both configurations.
That’s why people are talking about micro inverters and other add ons to keep energy flowing. I a lot of these issues are minimized in flat arrays – cells in series get even illumination, or at least it’s easy to ensure. Both parallel and series can be used productively.
Except for decorative tree-shaped solar collectors, I suspect we’ll be using flat panels for years to come.
George E. Smith says: August 20, 2011 at 12:57 pm Sunflowers follow the sun.
Yes, they do, but the “solar tree” in this articles does not. That is its weakness in comparison with Nature, in terms of flux capture.
More generally, there are many plants with roughly vertical inflexible stems that have opposing leaf pair patterns that do not spiral, but are pair-below-pair. If the sun is directly overhead, the top pair of leaves cast a shade on all of the pairs below. OTOH, the spiral arrangement is thought by some to to minimise the shade on lower leaves. It’s quite interesting to set up a model leaf shape (thin, long ones are best for the math), then examine leaf arrangements that allow light down to the lowest leaves. e.g. count how many leaves you make before one of them gets no light. Nature seems to avoid plants that have a single, circular leaf atop a vertical stalk. (Some water plants are this way, like the lotus). It’s almost as if, given the need for a stem to gain height and compete with neighbours, Nature found that the stem was more efficient if leaves all along it were photosynthesising, not just the top one taking all the light.
BTW, many of these comments apply to leaves and flowers similarly, because a flower is just a leaf that has had some extra gene activity.
As I said, full marks to Aidan for lateral thinking. Phyllotaxis is a fascinating topic, but the fascination should not be a diversion from sound design principles. The solar harvesting engineers worked out long ago the available, practical designs and their benefit:cost ratios for various applications.
At the risk of rabbiting on, this topic is one of the few that links observations of Nature’s grand designs to mathematics of reasonable complexity. A lesser DNA helix example, if you like. If you are into art derived from science, try ‘The Algorithmic Beauty of Plants’, a 1970s book by Przemyslaw Prusinkiewicz and Aristid Lindenmayer. It’s the first comprehensive volume on the computer simulation of plant development (L-systems). The book is no longer in print but a pdf version is available free online. Then follow the later references.
One reason none of them overeducated adult scientist “has thought of this” is because after thinking about it for a minute (as many have, even though they may not always have thought of flowery “like in nature” language at the same time), you realize that having some of your cells pointed to different time-of-day optimal directions simply even your chances re cloud cover etc., instead of peaking all at once — but you still have each cell at a suboptimal direction much of the day.
Since th cells are the most expensive part of the setup, your sensible choices are still: Either you turn all your aligned cells together towards the sun, which optimizes space use, or you arrange mirrors to direct max. sun at your cells all the time, to minimize mechanism and its power use.
When and where I was a kid, kids would build electronic sun-following mechanisms for science/engineering competitions for this purpose.
What this kid has done is dress up the bleeding obvious (non-equal direction distributes the optimal generation periods of different cells) with irrelevant language (Fibonacci, “nature”) and covered it with spotty data. I read the relevant sections of the article, and the voltage measurements which mean NOTHING are all there is.
He also quite possibly got a less-than-optimal baseline by the way he aimed the flat array.
I don’t know why some commenters here who have (going by what they’re writing in support of the poor kid) made no effort at all to understand how this should/would/doesn’t work (beyond reading and believing the “new and improved” conclusion, call the criticisms that try to understand what’s going on and fail to see any reason for the magical results “strawmen”.
It’s sad to see this kid understood so little of what he was doing, and got no help. No physics teacher to point out that a load and A/V measurements where a minimum requirement to make useful measurements? No clue fairy to point out that each cell by itself still acts as if in a flat array statically arranged in some (maybe good, maybe not) manner?
These writeups about motivation and development are usually BS, but in this case, the text apparently more than sums up the thinking process.
It is noteworthy that he made no experiments comparing different tree shapes.
At best, the kid is a budding con artist.
The awarders sadly seem to also have no clue about anything related to the subject.
Saying “like in nature” seems to be the only thing being rewarded.
Why is everybody here so credulous? I just happen to be an electrical engineer, but a math/physics-inclined 10-year-old armed with one solar cell, a photocell, a resistor and a multimeter could disprove these claims in half an hour.
Between his lack of desire to test his own ideas rigorously, and his clueles environment, the project kid looks like a future green-money-to-develop-nothing-grant recipient. Well done.
“”””” Geoff Sherrington says:
August 20, 2011 at 8:22 pm
George E. Smith says: August 20, 2011 at 12:57 pm Sunflowers follow the sun.
Yes, they do, but the “solar tree” in this articles does not. That is its weakness in comparison with Nature, in terms of flux capture. “””””
My entire point Geoff is that the Sunflower example is ample proof that Fibonacci trees are not even the best scheme that Mother Gaia can come up with for an efficient solar collector.
Yes it is remarkable that some of the schemes that Nature evolves over some time, can be shown to be rather efficient schemes, such as the CPC eyes, and plant shoots.
But don’t count the homo sapiens sapiens engineer out when it comes to who is better at solar collection. And I am not even a great supporter of it; but we are a whole lot better than Fibonacci trees, that we know have solar cells where the sun never shines.
This might be a good opportunity for skeptics to learn how to be erm, more skeptical.
Solar-panel “trees” really are inferior (or: “In which hopelessly inept journalists reduce me to having to debunk a school science project”)
http://news.ycombinator.com/item?id=2906538
http://webcache.googleusercontent.com/search?q=cache:JmlMNqVPKlsJ:uvdiv.blogspot.com/2011/08/solar-panel-trees-really-are-inferior.html+http://uvdiv.blogspot.com/2011/08/solar-panel-trees-really-are-inferior.html&cd=1&hl=en&ct=clnk&gl=us&source=www.google.com
Oh that is really great idealistic post. agreed with you yes we should use solar panels as nature has developed. keep on sharing such a great informative post.am impressed.
Suggestion: Use transparent tubes for the supports so that they do not block light to the solar cells when the light is at certain angles.
Complicated structure doesn’t always mean it costs more to produce once the infrastructure is in place. One example of this are the fractal antennaes that are used in mobile phones and in some cars. Fractals can let you pack what used to take a large surface area into a tiny one due to all the extra ‘surface’ made possible by fractals.
Fractals allow for more surface area for less material by increasing surface area through structure. This already applies to radio so there is no reason why it wouldn’t apply to sunlight.