# 13 year old researcher finds tree inspired solar collection more efficient

##### Aug 22, 2011 by Bob Yirka

(PhysOrg.com) -- Aidan Dwyer, a 13 year old Junior High School student from New York state, noticed that the phyllotaxy of the leaves on trees he was observing while hiking through the Catskill Mountains, did so in the form of a Fibonacci sequence. Wondering if there was a reason for it, he deduced that it might be because such an arrangement provides the most efficient means of solar power collection for the trees. To find out if this was the case, he built a small solar tree from PVC pipe and small solar panels, then built another in a normal flat panel array, attached voltage readers to both, and lo and behold, discovered the tree model array was indeed more efficient, at least during times of low or indirect sunlight. Dwyer won a Young Naturist Award for his efforts after writing and submitting his essay, The Secret of the Fibonacci Sequence in Trees.

The Young Naturist Awards are given (by the American Museum of Natural History) to two students from each grade, K-12, every year for young scientists who have investigated questions they have in the areas of biology, Earth science, ecology, and astronomy. Dwyer’s entry, took the known, that tree leaves grow in a Fibonacci sequence (where each number is the sum of the previous two) and applied it in a novel way that advanced the study of solar energy.

With trees, The Fibonacci pattern shows up in the way that limbs spiral around the trunk, specifically in the fraction that arises when computing the number of limbs it takes to complete a run all the way around the tree. Dwyer gives the example of the Oak tree which takes five branches to spiral two times around the trunk, giving the fraction 2/5. This is important because it was the basis of the model he built to replicate the tree structure. Interestingly, to find this fraction, and those of other types of , he fashioned his own measuring device out of a clear plastic tube with circle protractors on it. Branch angles were measured by inserting them into the tube.

Next, he built a small model tree (mimicking the Oak’s Fibonacci series as closely as possible) out of various sizes of PVC pipe to which he affixed small . After that, he put together a traditional flat panel solar array comprised of the same size solar panels. Then, after hooking up both to a data logger connected to a voltage meter, he then let them sit.

After analyzing his data, he found that the tree design appeared to be far more efficient than the traditional flat-panel structure during so-called off peak times, such as when the sun was low, and that the model appeared to be close to 50% more efficient overall during the winter. Not bad for someone who’s still a kid.

Dwyer theorizes that tree branches have evolved such an arrangement because it’s likely the most efficient pattern available, i.e. the one that best takes into account the shading created by branches or leaves hiding one another from direct sunlight.

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##### Cube
2 / 5 (4) Aug 22, 2011
good work kid!
##### Thex1138
1 / 5 (3) Aug 22, 2011
Solar panel trees will replace flat panels now...
##### lengould100
1 / 5 (3) Aug 22, 2011
Well fine, but not really applicable to anything until we've saturated the need for direct-exposure installations, a LONG way off yet.
##### stealthc
1 / 5 (2) Aug 22, 2011
excellent, we can have metal trees to replace the old natural ones with at the rate this world is going.
##### Kedas
not rated yet Aug 22, 2011
Since practical is not an issue:
What would be the best (mathematical) shape? (assuming you are not allowed to move them during the day)
##### antialias_physorg
3 / 5 (2) Aug 22, 2011
Depends on what you define as 'best'.

1) Total energy received: The conventional flat panels should excel at this. But this means that if you use many collectors throughoutthe country that you will get a lot of energy during peak hours (midday) and not much at other times

2) Most constant energy output: Here you should probably arrange the panels with most facing east and west because you must make up for low power during morning/evening times with more surface area exposed

The fibonacci series exhibited by plants has a different reason: As the plant grows leaves sprout sequentially. The series ensures that shading effects of one leaf on another are minimized.
##### Mike_Scherer
5 / 5 (5) Aug 22, 2011
Sorry, it's wrong.
Apparently he measured voltage, not power.
see here:
http://webcache.g...ior.html http://uvdiv.blog...ogle.com
##### GSwift7
3 / 5 (2) Aug 22, 2011
Maximum voltage is not the same as maximum wattage. I would like to see a measure of volts * amps. Look up MPP (maximum power point) and the I-V curve. You do not get the most power from a PV cell when it is getting maximum voltage. There is a sweet spot that maximizes voltage and current, as they are diametrically opposed. There are also low-maintenance passive tracking systems that will make linearly arranged PV cells much more efficient than any other design. I suspect he is getting high voltage at the expense of current. I will remain skeptical of this claim.

http://en.wikiped...tracking

Note: MPP tracking is not a physical movement of the PV cells, it is "tracking" of the voltage versus the current at the inverter. You "track" the voltage and make the resistance at the inverter match the voltage to maximize the power delivered. Physical tracking is a completely different topic.
##### Eikka
1 / 5 (1) Aug 22, 2011
In a sense, the open voltage of a solar cell is representative of the total radiation it recieves.

A photovoltaic cell is modeled by a constant current source, a diode, and a resistor all in parallel. The current source represents the recombination current, and the diode is the PN-junction of the photovoltaic cell.

http://chuck-wrig...age6.gif

A diode exhibits a voltage difference across the PN-junction that depends on the amount of current passing through it, usually about 0.5-1 Volts, and this shows up at the output of the cell. When you connect a load to the cell, some of the current is shunted out past the diode and that makes the voltage drop.

The relationship between solar radiation falling on the panel and its open circuit voltage is quite linear after a certain treshold, so it can be used to measure how much recombination current, and thus how much light there is falling on the panel.

http://openwetwar...resh.gif
##### Eikka
1 / 5 (1) Aug 22, 2011
Put simply, the light from the sun separates the charges inside the solar cell, kicking electrons from one layer to the other over the diode junction. That creates a voltage difference across the diode that grows until the electrons start leaking back through the diode to recombine.

The more charge is being separated, the higher the voltage and the higher the recombination current.

Of course, a very small increase in voltage over a diode in the forward direction is going to let a very large current through - or a very large current has to pass through before the voltage increases significantly. That means you need a fairly sensitive voltmeter to measure the difference.

##### Y8Q412VBZP21010
not rated yet Aug 22, 2011
excellent, we can have metal trees to replace the old natural ones with at the rate this world is going.

Oh dear, think how frustrated all the woodpeckers will be!
##### Isaacsname
1 / 5 (2) Aug 22, 2011
Idk...yay for the kid and all, but the efficiency of future solar panels will be based on microscopic qualities, not macroscopic design. This is a good idea for panels that are only capable of ~ 21% efficiency, as are most current commercial panels, but when we are able to boost that to higher levels of efficiency, a flat panel will do just fine. I do believe I have seen some articles concerning nanoscale design of PV panels here on PO. Still though, looking to nature for design inspiration is a wise move. Not all plants that are apically dominant follow the Fibb sequence with nodes/branching, and many don't maintain that form from vegetative to flowering states, they change physically through the seasons, so to say it's the most efficient when if it where nature would design everything like that, ...smart, but needs more thought. I think the kid should also study botany/horticultural science, he's got a bright future.
##### aroc91
5 / 5 (3) Aug 22, 2011
A little late, eh Physorg? Posting the original article even after it had been debunked? Fail.
##### kevinrtrs
1 / 5 (9) Aug 22, 2011
Dwyer theorizes that tree branches have evolved such an arrangement because its likely the most efficient pattern available, i.e. the one that best takes into account the shading created by branches or leaves hiding one another from direct sunlight

It is certainly a very wise mind that spotted such a mathematically interesting arrangement.

Perhaps Dwyer should also consider that the tree arrangement was DESIGNED by a much more superior intellect who created everything in the first place. This is a much simpler explanation than grasping at un-supportable evolutionary faith assumptions.

##### aroc91
5 / 5 (2) Aug 22, 2011
This is a much simpler explanation than grasping at un-supportable evolutionary faith assumptions.

Too obvious, kevin.
##### Shakescene21
1 / 5 (1) Aug 22, 2011
The picture of the experiment shows that the "tree" panels are much higher off the ground than the "roof" panels. For a scientific experiment I would think that they shoud be at the same height. Unless its a wide-open field, lower spots tend to get more shade than higher spots. (Hopefully, this effect was somehow corrected for in the experiment.)
##### MorituriMax
1 / 5 (1) Aug 22, 2011
that the tree arrangement was DESIGNED by a much more superior intellect who created everything in the first place.

Yawn, Really? I don't remember reading anywhere about forests of solar panel trees being discovered by anyone. For billions of years the most complex structures on Earth were... mountains. Basically zillions of tons of dirt on top of more dirt. All hail the mighty creator, designer of Rock Piles!
##### Callippo
3 / 5 (2) Aug 22, 2011
##### marraco
not rated yet Aug 22, 2011
It may have important applications on sensors and some antenna design.
##### hush1
1 / 5 (1) Aug 23, 2011
As a plant, we dia/para-heliotropists track light. Just don't ask us what we are trying to maximize and how we know what just right for us. Why track the sun, if the sky is blue? - the range to which we are more sensitive?

Anyway, congratulations Aidan Dwyer. Next time, water us before we wither and shrivel, our 'photovoltaic' doesn't short circuit, we promise.

##### antialias_physorg
3 / 5 (2) Aug 23, 2011
Yawn, Really? I don't remember reading anywhere about forests of solar panel trees being discovered by anyone.

You also have to hand it to the 'designer'. Plants are about 3% efficient when it comes to harvesting light for power. If there is a designer then he's a particularly inept one.
##### hush1
not rated yet Aug 23, 2011
"Efficiency should not be confused with effectiveness: a system that wastes most of its input power but produces exactly what it is meant to is effective but not efficient. The term "efficiency" makes sense only in reference to the wanted effect."

Nature is 100% effective.

Kevinrtrs existence is only a test: to see if we are willing to abandon beliefs of nature.

Only a designer can possess less than zero efficiency (input)
to create even less effectiveness (output). Example?
Kevinrtrs.

##### Humpty
1 / 5 (1) Aug 29, 2011
Big solar panel arrays - sunrise to sunset solar tracking = MAXIMUM power harvested.
##### Deesky
4.4 / 5 (7) Aug 29, 2011
You also have to hand it to the 'designer'. Plants are about 3% efficient when it comes to harvesting light for power. If there is a designer then he's a particularly inept one.

Not really. Well yes, the designer bit is bullshit, but regarding the 3% efficiency, why is that a fail? Clearly the world is covered by plants of all types, which means that they survive quite well indeed. Why would they need to be more efficient than they already are under the prevailing environmental conditions?
##### moebiex
not rated yet Sep 01, 2011
Big solar panel arrays - sunrise to sunset solar tracking = MAXIMUM power harvested.

But what is going to work for us- us being society and including small-hold farmers in China, India and the US etc as well as the ever-larger corporations that are bending and sequestering physical, financial and intellectual resources for their priorities. Remember: corporations have been characterized as "psychopathic" in nature, an emergent property even with the many good and decent people working in them. In a runaway evolution, truly efficient and effective systems may not include room for all, or perhaps one day any, of us. Just a little something else to think about as we imagine optimal designs.

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