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13-Year-Old Makes Solar Power Breakthrough by Harnessing the Fibonacci Sequence

inhabitat.com

51–60 of 151 posts

Re: 13-Year-Old Makes Solar Power Breakthrough by Harnessing the Fibonacci Sequence

#51

Inhabitat credits treehugger.com as its source. Treehugger's article is not breathless about biomimicry, not spread over two pages, and not interrupted by adsense and images. http://www.treehugger.com/files/2011/08/13-year-old-makes-so... Edit: The source of treehugger's article is Aidan's own article, which is better still, and addresses briefly some of the issues raised in comments here (e.g., about fixed vs. track…

In part, this is why it says in the guidelines:

    In Submissions
    ...
    Please submit the original source. If a blog post
    reports on something they found on another site,
    submit the latter. 
http://ycombinator.com/newsguidelines.html

Your last link has now been submitted by someone as a separate item and is just so much better.

http://news.ycombinator.com/item?id=2902496

Re: 13-Year-Old Makes Solar Power Breakthrough by Harnessing the Fibonacci Sequence

#52

So perhaps this is a question that others have answered, but what springs to mind for me is: why? I get that trees that follow the Fibonacci sequence are more productive, but without an answer to why that is, it remains a bit of a kludge. I would love to see some explanation of why this configuration is optimal.

Yeah, that's a bit fishy. Without an explanation, I'm skeptical that the Fibonacci sequence is actually important. Perhaps any branching arrangement of solar panels performs better than a flat one.

Re: 13-Year-Old Makes Solar Power Breakthrough by Harnessing the Fibonacci Sequence

#53

So perhaps this is a question that others have answered, but what springs to mind for me is: why? I get that trees that follow the Fibonacci sequence are more productive, but without an answer to why that is, it remains a bit of a kludge. I would love to see some explanation of why this configuration is optimal.

Broadly speaking ...

If leaves are space a rational number divisor a/b of 360 degrees around a trunk, then after b turns, leaves will directly shadow each other. To avoid this you need the amount of turn between leaves to be as difficult as possible to approximate by a rational number.

Using continued fractions we can see that the most difficult rational to approximate is

1 + 1/(1 + 1/(1 + 1/(...)))

which is (1+sqrt(5))/2 which is the Golden Ratio.

You can also get better packings by using the Fibonacci Spiral, which again gives the Golden Ratio:

http://en.wikipedia.org/wiki/Fibonacci_sequence#In_nature

You can look these things up if you're interested.

Re: 13-Year-Old Makes Solar Power Breakthrough by Harnessing the Fibonacci Sequence

#54

Inhabitat credits treehugger.com as its source. Treehugger's article is not breathless about biomimicry, not spread over two pages, and not interrupted by adsense and images. http://www.treehugger.com/files/2011/08/13-year-old-makes-so... Edit: The source of treehugger's article is Aidan's own article, which is better still, and addresses briefly some of the issues raised in comments here (e.g., about fixed vs. track…

The kid's own article is great. He explains all the steps he went through and the things he learned along the way. He learned about history, biology, the scientific method while doing something that interested him. Props to his parents and/or teachers who stimulated him to go through with this.

I don't think his 'invention' is that revolutionary. If you don't want your solar panels to overlap, it makes sense to choose step sizes that are coprime (which consecutive fibonacci numbers are). I don't think the invention matters that much here though. Aidan is obviously a bright kid and I'm sure he'll go on to do interesting things.

Re: 13-Year-Old Makes Solar Power Breakthrough by Harnessing the Fibonacci Sequence

#55

The comparison is against a flat row of cells that do not track the sun. I suspect that it will not do better compared to an array of cells that do track the sun. Basically the tree of cells are arranged in different angles so that as the sun moves some of them will always be receiving optimal sunlight when their normal is parallel with that of the incident light. Very nice insight, especially for a kid his age. I ce…

"Basically the tree of cells are arranged in different angles so that as the sun moves some of them will always be receiving optimal sunlight when their normal is parallel with that of the incident light."

Except it's trivially impossible to generate more energy like this (as he claims)! If a set of solar panels is independent and non-interacting (e.g., they don't shade or heat each other), then their total power output is simply the sum of their individual power outputs. And so their total energy outputs (integrated power) is the sum of their individual energy outputs. (Necessary distinction because their power peaks may occur at different times).

P_tot = Σ P_i

∫ P_tot dt = ∫ (Σ P_i) dt = Σ (∫ P_i dt)

E_tot = Σ E_i

If there is an unqiue optimal orientation for a single static panel (which under realistic assumptions there is) -- optimal in terms of maximizing energy output, E -- then the optimal orientation of a array of independent solar panels is just the same orientation, iterated. Combine inferior panel orientations, and their total remains inferior.

E_i Σ E_i And all those panel angles in his "tree", facing non-South, up, down, towards a wall... they are individually inferior to the single 45° south-facing panel in his static array. So combined together they are still inferior.

Where did his experiment go wrong? I'd start with the shade issue. The whole setup is in intermittent shade (note the tree shadows); and one experiment is sitting near the ground, the other is mounted on a pole. Looks like different shade environments. His output graphs show that the entire flat array is sometimes in total shade, at a time when the pole-mounted "tree" is not:

http://www.amnh.org/nationalcenter/youngnaturalistawards/201...

Another fatal flaw (I had to look this up to check) is that he is measuring voltage, not power, and they are not linearly related in photovoltaics. Actually, the open-circuit voltage (what you get if you stick a voltmeter over a solar cell, when it's not hooked up to a load) is practically independent of irradiance:

http://i.imgur.com/SWGjV.png

This from the solar module datasheet here:

http://www.bpsolar.us/products/3-series-solar-panels-polycry...

Open-circuit voltage going from 200 W/m^2 to 1,000 W/m^2 only increases from 34 V to 38 V. Power output, with a real load, would go up by about 5 times.

So, he never really measured energy production, or anything that remotely approximates it.

Re: 13-Year-Old Makes Solar Power Breakthrough by Harnessing the Fibonacci Sequence

#56
post #32

I wonder if some genetic algorithm style testing of angles and placements could yield even more efficiency? Seems possible that nature hasn't yet hit optimal design in this area.

http://www.ted.com/talks/view/lang/eng//id/450

Interesting, did they make any progress since then?

Re: 13-Year-Old Makes Solar Power Breakthrough by Harnessing the Fibonacci Sequence

#57

Earlier quoted context omitted.

Last paragraph sums up the possible advantages- Aidan wrote: "The tree design takes up less room than flat-panel arrays and works in spots that don't have a full southern view. It collects more sunlight in winter. Shade and bad weather like snow don't hurt it because the panels are not flat. It even looks nicer because it looks like a tree. A design like this may work better in urban areas where space and direct sunl…

>>The tree design takes up less room than flat-panel arrays Very true. That is a huge advantage if space is a concern.

TO be specific - If "horizontal space" is a concern. Solar Tree consumes vertical space.

Re: 13-Year-Old Makes Solar Power Breakthrough by Harnessing the Fibonacci Sequence

#58
post #10

The comparison is against a flat row of cells that do not track the sun. I suspect that it will not do better compared to an array of cells that do track the sun. Basically the tree of cells are arranged in different angles so that as the sun moves some of them will always be receiving optimal sunlight when their normal is parallel with that of the incident light. Very nice insight, especially for a kid his age. I ce…

Now I don't disagree that an array of cells that track the sun would produce better results, but it would be fair to assume that this would cost energy. Keeping that in mind, do you think it would still provide better results?

Tracking panels may prove to be a better design for maximum power output.

However, there are other constraints to engineer for. Cost and durability (through simplicity of parts) come out ahead in a design with no moving parts.

At the end of the day, it's better to have knowledge of both designs to know what's most appropriate for your needs.

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