I need someone to explain this to me.

Setting it straight about science fair solar energy breakthrough

There’s been a lot of stories about arranging solar panels to mimic leaves on a tree, thereby boosting their efficiency. But before reading that story you might want to check out this blog post correcting some flaws in that breakthrough (page is down, here’s a cached version).

Before we go any further, we’d like to point out that the original work was done by a seventh grader. He looked at leaves on trees and postulated that the Fibonacci sequence can be found in the layout of leaves, and that by laying out solar cells in the same way you can capture more sunlight. Comments can get negative fast around here, so remember that trashing his work may discourage other kids from participating in science fair events.

Anyway, long story short: there were some issues with original assumptions, and about what was actually being measured during testing. The article linked at the top covers the fact that the cells were not measured under load, and that simple calculations can show why the tree-mimicking-cell-placement can be proven sub-optimal to 45 degree, south-facing solar farms.

[Thanks Jeffery and Steve for the original article and Brian for the follow-up article and cached link]

Comments

  1. GZ says:

    Innovative idea and way to observe the natural world. It’s a shame about the testing method.

    Although it’s not the most effective method for SPs it’s interesting to look at the growth process of a tree. The cost of growing a leaf “at random” versus the cost of maintaining it over time and when does the leaf become abandoned.

    Gotta be knowledge of value in there. Thats the great part of science!

  2. loans says:

    It’s great to see kids thinking about science. It’s great to see kids making connections between things in the world around us. Even if it’s not surprising that the kids aren’t really making astounding breakthroughs, this spirit of curiosity is important.

  3. sam izdat says:

    Actually not an innovative idea. Niklas covered this in the early 90′s.

    Cool that a science student rediscovered it, and a good “teachable moment” about checking the background literature.

    Plant Biomechanics and Light Interception

  4. hospadar says:

    I do wonder if there is still some application for a shape more exciting than just a big bank of sun-pointing panels (even if it’s not a mystic fibonacci arrangement). Probably not in bulk power generation, but perhaps for:
    a) art
    b) solar-powered public electronics (street lights, parking meters, etc)
    c) solar powered devices with an obstructed view of the sun
    d) solar arrays with space constraints
    c) solar arrays which for whatever reason (maintenance, durability, etc) can’t be sun-following

    Probably only A and maybe C are really applicable, but it’s an interesting avenue of thought. they sure are a lot prettier than big flat panels anywho.

    • Gene says:

      I think there’s certainly room for “sub-optimal” arrangements in terms of art. As solar panels become cheaper, their aesthetics will start to become as important as their efficiency for many real-world deployment scenarios (primarily overcoming NIMBY.)

    • Cynar says:

      The sub-optimal designs can still become useful when the criteria change. With a tree it needs to be able to make sugar no matter what the light is doing. It has to fight with other plants for light and it has no knowledge of North-South to work with. The Fibonacci layout is optimal for a ‘random’ tree in a ‘random’ location. It maximises the minimum light the tree will receive and so avoids it being starved out.

    • austin says:

      i would certainly see A as a possibility. i remember story fox news(surprise surprise) ran where a town installed a solar panel and various members (mind you not even the majority a small minority, but fox news doesnt care about that eh) got all pissy saying its ugly or a snow hazard or whatever. but a nice tree shape protruding off of the telephone/power lines would add a bit of power to the grid and make the lines look a little more organic. well except the blue and metalic colours…

      • bigbob says:

        Keep your political opinions to yourself. Everybody says that FOX news is so biased, have you ever watched ANY news station? FOX just happens to be the only one that is biased on the conservative side so hippies like you complain, while conservative people don’t get all bent out of shape about the liberal news stations…

      • Bear Naff says:

        This reply is directed to “bigbob”:

        Austin was not expressing a political opinion – the fact that the Fox News channel is biased beyond anything else seen in mainstream reporting is not at issue. FN’s daytime schedule is mostly commentary with small nugget of processed news product thrown in for flavoring. If you’re looking for good reporting from a conservative-leaning source, I recommend The Economist.

      • bigbob says:

        @ Bear Naff

        I do understand and agree with what you’re saying. FOX news is primarily commentary that is clearly biased on the conservative side. I still, however, believe that they are no more biased than any other news network/show, they just don’t try to cover up their bias.

    • Tim says:

      My university has started installing solar umbrellas… probably ridiculously inefficient but nevertheless very cool and gets people thinking!

      http://ideasforus.wordpress.com/2011/08/08/did-you-say-solar-powered-umbrellas/

  5. Jelle says:

    Somehow I am a bit lost by the first comment above. I just read a informed article explaining why some ‘invention’ by a 13yo isn’t really an invention, but a lot of hogwash and some magical /fibonacci/ thinking.
    That is great actually, because it is taking peer review (well, not peers perhaps, I don’t think the author is a 13yo) beyond the realm of stuffy scientific papers. It would be kinda fun to hunt down the journo that first published this crap and lampoon him/her about it.

  6. Dax says:

    “Most importantly, by mistake he did not measure power outputs from the solar cells. Instead he measured voltage, without a load attached (“open circuit”). They are barely related — in solar cells, voltage is actually almost a constant, independent of power.”

    This is false.

    A solar cell behaves like a constant current source where the current is constantly flowing across the P-N junction, and the strenght of that current depends on the amount of sunlight falling on the panel.

    This recombination current has a voltage drop across the junction, and this drop shows up as the open circuit voltage of the cell. The junction is essentially a diode, and you connect the load parallel to it, which causes it to act as a voltage source.

    The open circuit voltage behaves exactly in the same way as a forward-biased diode in regards to the recombination current inside the cell, which means that for a significant amount of current (significant solar radiation) there is an almost linear relationship between the output voltage and the amount of sunlight falling on the panel.

    Knowing the amount of recombination current gives you the amount of power you could draw out of the cell directly.

  7. Dax says:

    Granted, once the junction reaches forward saturation at around 0.6 – 0.7 volts, the difference in voltage to a difference in current is very small, but with a fairly sensitive voltmeter it would still be trivial to measure how much sunlight is falling on the panel from the open circuit voltage alone.

  8. YT2095 says:

    It`s worth remembering also, that there`s no such thing as a “Failed experiment”, only more data! ;)

  9. Bojan says:

    We need more blogs like “uvdiv” is.

  10. anyone says:

    as much as i’d hate to “trash” on a 7th grader…sometimes if you don’t take these measures you end up with “free energy over unity generator” problems as seen all over youtube. people start believing these lies and the population as a whole gets dumber.

    hackaday, shame on you for taking the “it’s ok to be dumb” route. it wastes others time and possibly tricks them into believing something ill-founded and flat out wrong.

  11. Dax says:

    Or, in the case that there are many cells in series, the slight difference in voltage is amplified by the number of cells recieving the sunlight.

    The equivalent circuit diagram for a photovoltaic cell is a constant current source, a diode, and a resistor in parallel. The CCS represents the amount of charge separation produced by sunlight, the diode represents the recombination path through the junction, and the resistor represents resistive leakage.

  12. Geirskogul says:

    Blog has been taken down, and archives show it was shit anyway.

    Do some more research.

  13. Hunter says:

    See I see this a different way. Seriously, is it okay for us to “peer review” a seventh grade science project? Did he make mistakes in his method, sure, but so will most aspiring scientists at one time or another. I don’t see this as flaunting an “it’s okay to be dumb” position, but rather one that seems to be forgotten all to often. A position of compassion for those trying to learn and reaching beyond themselves. Honestly I never had the drive to do this kind of work when I was in seventh grade, I was to busy trying to get pictures to download faster over my dial-up!

  14. therian says:

    And I still cant shut up people that he is not genius and did not make any breakthrough

    • fartface says:

      What about the guy in south africa that invented windmills for generating electricity? That one is still all over the internet on how he is a einsteinium level genius… for doing what everyone outside of africa has been doing with junk for at least 90 years

  15. Dax says:

    @Hunter
    “Did he make mistakes in his method, sure, but so will most aspiring scientists at one time or another.”

    The interesting thing is, many of his critics point out the voltage thing as a mistake, when it really is not.

    I don’t know if he actually did his reading on solar panels, but the fact of the matter is that the open circuit voltage is representative of the amount of sunlight falling on the panels, and therefore the available power. The data just needs a bit of interpretation to get the correct magnitudes out of it.

  16. jeff-o says:

    I say we call in the Mythbusters to settle this once and for all.

  17. jeicrash says:

    +1 for Mythbusters, and the fact that this became national news is just ridiculous. But then again the media does have a tendency to get ahead of itself without first verifying the info. I hope this kid keeps up the work and continues to experiment. Can you imagine being 13 (Man i wish at times) and having the whole nation nit picking something you made for school?

  18. asdfadfgasg says:

    “Comments can get negative fast around here, so remember that trashing his work may discourage other kids from participating in science fair events.”

    Seriously? Is this how lame people have become. What kid would really become discourage by some people on the internet?

  19. MS3FGX says:

    First off, the author of the blog post took the thing down for a reason. Why exactly is HaD ignoring the intent of the original author and publishing the Google cache link? Perhaps he thought better of the effect this could have on the student, and wanted to make amends by pulling it?

    Second, nobody really wants to bash a 13 year old kid; but the fact of the matter is that there were multiple mistakes in the execution and testing of his theory. By rights, he should have gotten a B on his project at best, he certainly shouldn’t have won a national contest or gotten this kind of media attention.

    The biggest part of this story is how completely inept so called technology journalists are, or for that matter, the educators who are in charge of administrating these fairs.

    • Zuber5 says:

      The blogger took it down because the second part of his argument was wrong. He assumed the sun was stationary. Last time I looked it moves across the sky making a 45 degree flat array exhibit variable performance, not constant as his equations assumed. If people are going to trash a 13 year old’s ideas then they had better be right.

  20. therian says:

    there was one good post about PC BS that now gone, HAD you lost all credibility with this censorship

  21. therian says:

    or simply now comment are too boring and I viit less and less

  22. NXK says:

    It’s ironic people are calling for Mythbusters, as they have terrible methodology in their ‘experiments’. That being said, it is a fun show.

    • KXN says:

      Zombie Feynman gives you an F!

      http://xkcd.com/397/

      • NXK says:

        No, Zombie Feynman gives me an A+.

        The point the xkcd comic makes applies to the seventh grader just as much as it applies to the Mythbusters. I never said what the seventh grader or the Mythbusters do isn’t science, I merely pointed out the irony of using the Mythbusters to take a 13-year-old kid to task for his scientific rigor. Also, pointing out an error in methodology is not, in and of itself, a value judgement on the idea being tested.

        I also ‘show them some love’ as Zombie Feynman requests, it was the second of the two sentences in my original post.

    • therian says:

      exactly, sometimes I watch and want to scream on about wrong set up or unscientific method

  23. adam says:

    Honestly testing the cells unloaded isn’t to bad of a mistake. I know an EE senior that made the same mistake. I probably would have done the same thing at 13. If you are trying to figure out the avaliable power from a panel then you need a load, but i don’t expect a 13 year old to know that, I certainly didn’t when I was 13. Heck I don’t even expect most High School Science teachers to know that. I was lucky, My High school physics teacher was an actual physicist, He even helped develop the original Starlight Scopes. But i doubt that many have that kind of cred. But they should have done some fact checking, even taken it to a university before telling of an energy breakthrough.

    That being said, I’d still give the kid an B+ for the idea about the Fibonacci Series,especially if he did a good job documenting and presenting it. It’s a good idea and show creative thinking and an understanding about how the world works that will serve him well. Somebody get this kid a scholarship.

  24. Z says:

    I applaud this kids creation of a hypothesis, testing and conclusion of an idea he wanted to know more about. He may have not used the best method by scientific standards but he tried, which is more then a vast majority of people do. I am sure that next time he will do even better, as long as he hasn’t been discouraged by negative responses online.

    We sometimes seem to forget that on the other side of all this text we read online everyday is a person. It matters how you respond to someones work online, especially when they haven’t even hit adulthood yet.

  25. Ted says:

    It is not the measuring mistakes that bother me, but the idea that there is some magic in the arrangement of leaves on a tree (fibonacci), and how easy it is for many to buy into it, just because it is “green”.

    • Marco says:

      I am confused by all these comments. His measurements show a difference of 0.8V in peak voltage. Is that a measurement error, caused by suboptimal panel placement, or some noise ?
      Does an 0.8V increase of open circuit voltage mean potential increased power output or not ?

      • therian says:

        by arranging solar array 360 you might get more voltage but as soon as you try to load it the panels in shadow will act as resistors and there is more shadow panels

  26. cmholm says:

    So, let me get this straight: HAD posted the original entry regarding Aidan Dwyer’s science project. There were obviously some problems with the project, but it was still interesting to see someone take the first steps towards doing real science.

    Now that the project’s shortcomings have been widely broadcast, HAD completely removes the original post, and replaces it with a debunk link.

    I’m fine with posting a correction… but, was it necessary to yank the original, rather than edit it with a link to the correction?

  27. Chambon says:

    Look, the kid did a nice job. Deserving of national attention? Not really. Most likely the son or nephew of a friend of the judges of the competition…

  28. reformer says:

    When I was in 7th grade I was still trying to beat Super Mario Bros on the NES, had never even heard of a fibonacci sequence. Props to this kid.

  29. am still thinking of making a solar tree as i think they look cool and it will make a great gift for my friend.

  30. F4r4d4y says:

    Cool. He failed at 13 and learned early the importance of failure (especially when nobody else publicly noticed for a while). I assume less than 10% of anyone reading the first article/reddit/cnet/etc on it will EVER see a redaction or Ohm’s law spelled out about this. I’m impressed as hell he was able to set up the experiment!

    The real failure here was the blind obsession with green tech that makes everyone check their brains at the door (side note; there are few reporters left any more, there are just employees who repeat what they see on the AP wire and inject their own bias…probably in effect here also) – even Popular Science published this as fact without a hint of investigation. Everyone couldnt WAIT to wank about the fantasies they had about some shining utopia heralded by a youth, brighter than us all.

    I’ll be surprised if this poor reporting/flash media storm doesnt give this poor kid a complex.

  31. mikelist says:

    leaves and solar cells share a purpose, to gather light/heat, but the goal is different. leaves are arranged to allow the most leaves to get sufficient light (mumble, averages, mumble, not suggesting ID here)to support the plant, where the goal of a solar array is to get the most overall energy. depending on the organism, those aren’t always the same. but particularly observant idea, even if his conclusion was incorrect. he knows twice as much about it now.

  32. Frogz says:

    i want to bring 1 point to the arguments bashing on the 13 year old…
    look at picture 7 on the official site…
    he used cheap “scrap” cell solar pannels
    they are ALL wildly different shapes and sizes
    comparing them based on ANYTHING is flawed if they panels arnt identical…

    • macona says:

      People are not really bashing the 13 year old, they are bashing the media and the “experts” who should have caught this before it was blown all out of proportion. Media sees kids and green and they go crazy.

  33. Doktor Jeep says:

    This is the kind of idea I would have had when I was 13 if I were not so stupid.

    I did try to build an ultralight plane though.

    Had I the means I would send the kid some satellite-grade solar cells. The project is worthy of investment.

  34. Luke says:

    Read the sites covering him, read the comments…So much uncomfortable.

  35. therian says:

    I remember couple years ago I read about ‘hairy’ solar panels, shape of hairs instead of flat give so much more surface area and light trap by bouncing from hair to hair, efficiency was increase by 300, too bad I haven’t hear anything about this research since then

  36. promet says:

    Wow, how…deflating. It’s great that all of this rigor, and proper perspective is getting applied to the whole situation.

    One can’t help feel that “the Internet” has sort of crept up on this kid and slapped his lunch tray out of his hands, all in front of that one girl he likes.

    All on Taco Puff Wednesday too, dang…

    I hope he keeps his chin up.

  37. Carlos in ATx says:

    Actually think the kid is on to something here. Firstly, solar tracking systems are expensive, not known for their reliability and require a power source to operate them. The one term I didn’t hear in all the critique was cost per kilowatt/hour. I’d like to see some cost-benefit analysis of solar tree versus active tracking for a given amount of ground space. A solar tree may other benefits such a more micro-climate creation in an urban environment(read as shade) than ground hugging active -tracking arrays in for-off desert regions.

  38. Anthony says:

    The biomimetic arrangement is never going to match a carefully optimized solar tracking system. But when you need to set up a solar power station fast, without thinking about it, and get optimal power from your array, the fibonacci arrangement is probably a good one.

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