13-Year-Old Uses Fibonacci Sequence For Solar Power Breakthrough 410
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.
He just used more solar cells (Score:2, Interesting)
He's used 18 cells on the tree, but 10 in the flat array. So an increase of 80% in cell numbers results in an increase of 20-50% in yield. I don't see a massive future for this.
His testing was pretty bad (Score:4, Interesting)
You caught part of it , but even positioning of the flat array versus his "tree" skewed the results. There were times he shows where the tree was not in shade but the flat panel was fully in shade. The claims of increased efficiency ignore using panels that have mechanisms to allow them to track the sun. Plus he isn't measuring the right output of photo cells, he should have measured energy production.
As for his idea of trees, btdt http://farm4.static.flickr.com/3206/2807030740_25f3f2fa53.jpg [flickr.com]
unaccounted-for variables (Score:3, Interesting)
- He set the flat array at an angle of 45 degrees. Is that the optimum angle for solar panels at his latitude?
- as mentioned elsewhere, more panels in the tree array.
- The photos show both arrays being partly shaded by trees in the yard. Since the arrays aren't at exactly the same position, the amount of shade can be different. The tree array is at an advantage: more distance between the panels means that it's less likely that more than one panel is shaded by a tree branch.
Still, it's an interesting result that raises a few questions:
- in current solar panels, the wafers are connected to their beighbors to minimise the amount of wiring. But this means that whole panel drops its output below the threshold if one row of wafers is shaded by a tree branch. Maybe we'd get more energy out of an array if we connected distant wafers in series instead, so a tree branch shadow is less likely to drop the output of a series of wafers below the threshold.
- is it possible to increase the output of an array by putting parts of it at different horizontal or vertical angles?
Re:Makes sense... (Score:5, Interesting)
Small nitpick - nature will optimize to a local minimum but not necessarily the global minimum. i.e. the plants might be stuck with the 'good enough' design instead of the fully optimized version. In this case, it appears that the 'natural' solution is pretty good and well optimized, especially with the low fluence case (i.e. the winter).
It's a minor but important nitpick because not all plants use the same spread and angles - I haven't read up on this, but it implies to me that there area niches in an ecosystem to have other solutions (kind of like the scavengers around the top predator - the predator might be really successful at getting it's food, but there might still be meat on the bone for the scavenger birds.) To bring the analogy back to topic, there might be other spacing/angle solutions that, alone, are worse, but with a secondary system placed interstitially, result in an overall more efficient solution. (Barely-thought about examples: placing a reflective base below, and having two-sided panels to catch other angles - or, perhaps studying the placement and angles of vine leaves can give an interstitial solution.)
So, locally minimized solutions can still be great, especially if a second-order approach cleans it up even further (as in the natural example.)
Re:Damn straight! (Score:4, Interesting)
SCIENTIFIC METHODLOGY FAIL
Sorry, but his experiment was NOT to determine a better way of generating solar power, if you RTFA it was an experiment to determine why the leaves on trees are arranged in specific patterns. If you study up a bit about photosynthesis, you'll find it has exactly the same "clipping" issues with regards to energy absorption that a cheap solar panel does. It was a pretty ingenious test to determine the (admittedly obvious) conclusion as to why leaves & branches follow the Fibonacci pattern. He probably should have tried some other tree-like but non-Fibonacci based arrangements, but he does address that point somewhat in his conclusions.
I guess you're saying there is no advantage whatsoever in determining the most efficient arrangement of cheap solar panels? They're common enough devices, so why not arrange them efficiently?
Re:Damn straight! (Score:2, Interesting)
Wow. Twice now. SCIENTIFIC METHODOLOGY FAIL
Please explain how either of these arrangements answer the question the kid was trying to answer? Once again, if you RTFA, he was trying to determine why oak trees arrange their branches according to the Fibonacci sequence. He was NOT trying to create a more efficient array.
To put it simply for those posters who don't understand basic science:
Question:
Why do branches on a tree arrange themselves according to the Fibonacci sequence?
Hypothesis:
The Fibonacci sequence arrangement provides a more efficient arrangement for photosynthesis:
Experiment:
Arrange a number of solar panels according to the Fibonacci sequence.
Arrange the same number in a flat panel arrangement. (ignore the f*ing photograph, obviously they took the photo AFTER he got the award, not during the experiment)
Measure the voltage output of both over a number of months.
For a grade 7 kid, it's pretty good science. Or to put it more eloquently:
http://xkcd.com/397/ [xkcd.com]
Also, great, you put a bunch of words on paper and claim that these provide a more efficient arrangement. I can do that too:
Obviously a tesseract arrangement would be far more efficient than either a dome or corkscrew arrangement. I can't believe anyone wouldn't of thought of that. Especially in grade 7.