5 ms·

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 su

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 certainly would not have thought of it.

rycs 15y ago
it makes a lot of sense, nature has been doing it for a lot of time :), I hope that other scientists elsewhere can also confirm that the improvements are so dramatic, I mean, having still/motionless cheap arrays that can perform 20%-50% better than the flat ones are great news!
- deleted 15y ago
  [deleted]
ebzlo 15y ago
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?
- deleted 15y ago
  [deleted]
- rycs 15y ago
  I'm not an expert here, but it's pointless to make tracking sun panels that costs a lot more if the outcome wasn't that great, I bet tracking sunlight is still more efficient even after spending energy to move the panels, it makes no sense otherwise. The real benefit of this is that you get a cheap motionless panel that performs a lot better than the flat version, this is specially important in places like Africa where you need to be as efficient and cost effective as possible.
  - palish 15y ago
    Indeed. The boy's design is extremely rugged and simple (no moving parts). It should be highly reliable someday.
  - TeMPOraL 15y ago
    SolarFlower.org - the open source solar collector - has a non-electronic sun tracking system that I think might be more efficient than PV-powered tracking. See http://www.solarflower.org/faq.htm http://www.solarflower.org/faq.htm.
- sankalpk 15y ago
  According to Wikipedia (http://en.wikipedia.org/wiki/Photovoltaic_system#Tracking_the_sun http://en.wikipedia.org/wiki/Photovoltaic_system#Tracking_th...): "tracking systems can increase viable output by up to 100%...For large systems, the energy gained by using tracking systems outweighs the added complexity (trackers can increase efficiency by 30% or more)" The new tree design can make 20%-50% more electricity. Wouldn't know till they do some legitimate tests but it seems like the sun trackers fare better.
  - tomp 15y ago
    Why compare the designs, when you can combine them? I'm sure that the tree design can be improved a lot more, by just slightly turning the "leaves" so that they face the sunlight more directly.
    - ebzlo 15y ago
      I am willing to wager the suggested "combined" design would produce a very similar results anyway. The tree design is likely not necessary if the panels are moving.
- eric-hu 15y ago
  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.
- lutorm 15y ago
  The real benefit of a tracking system is that it makes it possible to use a concentrator to focus more sunlight on a smaller PV area. The panel cost is mostly in the PVs, so increasing collecting area by using mirrors is more cost effective than just using more PVs. However, this setup only works if it's pointing right at the Sun, so it requires a tracker.
yxhuvud 15y ago
Moving parts cost a lot though. There is a reason for trees not to have them.
- MichaelApproved 15y ago
  But sunflowers have moving parts and they track the sun beautifully.
  - sjs 15y ago
    Sunflowers don't stick around for dozens of years or more.
  - randomdata 15y ago
    But the equipment starts to fail quite rapidly, especially when compared to a tree.
- baq 15y ago
  most plants try to aim leaves at the sun. don't know about trees, but certainly whatever i've got growing in pots does that.
- sliverstorm 15y ago
  http://www.youtube.com/watch?v=Ze8NV7cvW8k http://www.youtube.com/watch?v=Ze8NV7cvW8k
uvdiv 15y ago
"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 < E_opt (for i <- 1..N) Σ E_i < N * E_opt 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/2011/aidan.html 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 http://i.imgur.com/SWGjV.png This from the solar module datasheet here: http://www.bpsolar.us/products/3-series-solar-panels-polycrystalline 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.
- toppy 15y ago
  This guy is 13 ;)
ForrestN 15y ago
Wouldn't it be possible to track the sun with the tree model as well?

rycs 15y ago

it makes a lot of sense, nature has been doing it for a lot of time :), I hope that other scientists elsewhere can also confirm that the improvements are so dramatic, I mean, having still/motionless cheap arrays that can perform 20%-50% better than the flat ones are great news!

deleted 15y ago
[deleted]

ebzlo 15y ago

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?

deleted 15y ago
[deleted]
rycs 15y ago
I'm not an expert here, but it's pointless to make tracking sun panels that costs a lot more if the outcome wasn't that great, I bet tracking sunlight is still more efficient even after spending energy to move the panels, it makes no sense otherwise. The real benefit of this is that you get a cheap motionless panel that performs a lot better than the flat version, this is specially important in places like Africa where you need to be as efficient and cost effective as possible.
- palish 15y ago
  Indeed. The boy's design is extremely rugged and simple (no moving parts). It should be highly reliable someday.
- TeMPOraL 15y ago
  SolarFlower.org - the open source solar collector - has a non-electronic sun tracking system that I think might be more efficient than PV-powered tracking. See http://www.solarflower.org/faq.htm http://www.solarflower.org/faq.htm.
sankalpk 15y ago
According to Wikipedia (http://en.wikipedia.org/wiki/Photovoltaic_system#Tracking_the_sun http://en.wikipedia.org/wiki/Photovoltaic_system#Tracking_th...): "tracking systems can increase viable output by up to 100%...For large systems, the energy gained by using tracking systems outweighs the added complexity (trackers can increase efficiency by 30% or more)" The new tree design can make 20%-50% more electricity. Wouldn't know till they do some legitimate tests but it seems like the sun trackers fare better.
- tomp 15y ago
  Why compare the designs, when you can combine them? I'm sure that the tree design can be improved a lot more, by just slightly turning the "leaves" so that they face the sunlight more directly.
  - ebzlo 15y ago
    I am willing to wager the suggested "combined" design would produce a very similar results anyway. The tree design is likely not necessary if the panels are moving.
eric-hu 15y ago
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.
lutorm 15y ago
The real benefit of a tracking system is that it makes it possible to use a concentrator to focus more sunlight on a smaller PV area. The panel cost is mostly in the PVs, so increasing collecting area by using mirrors is more cost effective than just using more PVs. However, this setup only works if it's pointing right at the Sun, so it requires a tracker.

yxhuvud 15y ago

Moving parts cost a lot though. There is a reason for trees not to have them.

MichaelApproved 15y ago
But sunflowers have moving parts and they track the sun beautifully.
- sjs 15y ago
  Sunflowers don't stick around for dozens of years or more.
- randomdata 15y ago
  But the equipment starts to fail quite rapidly, especially when compared to a tree.
baq 15y ago
most plants try to aim leaves at the sun. don't know about trees, but certainly whatever i've got growing in pots does that.
sliverstorm 15y ago
http://www.youtube.com/watch?v=Ze8NV7cvW8k http://www.youtube.com/watch?v=Ze8NV7cvW8k

uvdiv 15y ago

"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 < E_opt (for i <- 1..N) Σ E_i < N * E_opt 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/2011/aidan.html 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 http://i.imgur.com/SWGjV.png This from the solar module datasheet here: http://www.bpsolar.us/products/3-series-solar-panels-polycrystalline 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.

toppy 15y ago
This guy is 13 ;)

ForrestN 15y ago

Wouldn't it be possible to track the sun with the tree model as well?