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Comment by DevX101 | Hacker News Reader

This article was posted last night, but taken down by this morning. I recovered it from google cache.

The author is exactly right. There's no way that a tree array of panels that are half not even pointing at the sun will outperform a linear array of panels that are mostly pointing at the sun. Panels efficiency is measured in Watts, and this kid is not going to be able to record their efficiency with a simple probe DMM. In order to get a full picture of what's going on with his arrays, he would need to hook both arrays up to a load and measure throughout the day, or better yet a battery array / charge controller and measure at the end of the day which array produced more power.

I kind of wanted to say something yesterday, but really didn't want to pile on the kid, and everyone here just wanted so badly for the kid to be a genius. The few comments that pointed out that he was wrong were voted down.

This is something that really bothers me about science fairs. Back when I was 13 years old, I did a school project to redesign a local troublesome intersection. I just made a model of what it might look like and people loved it and they even wrote about it in the paper and displayed my model in the municipal building, and talked about what a bright young kid I was.

Now that I'm older, this bothers me a lot because in doing the project I didn't do any real research, I didn't talk to any traffic engineers, I didn't learn about intersection designs.. I didn't learn anything really. As an adult, I can see that my plan for the intersection was silly and unworkable.

I kind of wish that schools emphasized mentorship programs rather than science fairs. Kids would learn far more by partnering with knowledgeable adults to do their experiments, rather than having these silly competitions where nobody learns anything and the winner is the kid who puts the most work into having the nicest presentation.

> There's no way that a tree array of panels that are half not even pointing at the sun will outperform a linear array of panels that are mostly pointing at the sun.

While this is so very true in the theoretical sense of the term, I gave this a very short thought, and there might be edge conditions that could indeed lead to "better power with tree-shaped panels" (1), now that I think about it. There is a term that you are (rightfully) neglecting: the size of the system, and incurred energy loss due to Joule Effect.

If the distance between panels arranged in a linear way is large, then it might be more efficient to place additional panels closer to the output circuit, maybe above it, in such a way that it doesn't overlap and yep, maybe even with a different orientation, just to optimize the distance between producer and consumer, and thus reduce resistance and energy losses. But that would probably only be valid for specific sets of distances, positions, hour of the day (seasons, voltage, quality of the conductor material...), but that's only because the studied system shifts to be more of that of an Energy Transmission System than that of an Energy Production System

(1) or sphere-shaped or pyramid-shaped or pokemon-shaped for that matter...

Genuine (if idle) question- why do plants have leaves which permanently face away from the sun? It's not zero-cost to the plant to produce such leaves...so why does it?

My educated guess is that there is some benefit to having a uniform distribution of solar power over the course of a day. If all leaves pointed in one optimal direction, then more energy would be directed at the tree in a single day, but it would collect this energy in a narrow time span. It's possible a tree could not efficiently process this energy in this time span, similar to how you would not be able to eat a deer in one sitting.

By having a generally spherical orientation of leaves, the tree is always receiving power throughout the day.

Again, this is all just my hypothesis.

All the cells in one string (i.e. all the cells in series, connected positive to negative terminal) need uniform sunlight. Otherwise some cells can go into reverse bias and dissipate the power of the other cells in the string. This happens, for example where there is uneven shade, or dirt on the array.

leaves serve other purposes as well (for example, stomata are used for gas exchange) which do not directly involve sunlight.

Remember how evolution works: If a being stumbles on an imperfect solution and then never experiences a selection pressure strong enough to force a change, it won't get changed. Similarly, if there never arises a mutation that would change it, it won't get changed. Evolution is not focused on finding optimal solutions; it may eventually find one, but it is not guaranteed as part of the process.

There is a major assumption throughout this thread -- that trees maximize solar energy capture. In fact, the exact opposite is true. Many features of trees (and plants in general) reduce the efficiency of solar conversion. This is useful for plants to reduce the need for other resources like water. If leaves were arranged to optimally harvest solar energy, the tree would need an enormous amount of water to combat the resultant heat and evaporation.

Trees only convert 1-3% of the solar energy that falls on them -- so trees are a very poor system to mimic if the goal is to maximize solar energy collection.

a.) If adding leafs is has net gains, the tree will do this even if it's not the most efficient way (where say it could only have 50% of the leafs). b.) A tree is fighting with it's environment for light and space, a linear setup of leaves might not be the best position to fight other plants for light. c.) A tree needs to support all leafs with water, nutrients etc. A tree layout might be more efficient

> everyone here just wanted so badly for the kid to be a genius

And there's nothing wrong with that. It was an interesting, creative and thoughtful experimental approach that singled him out from the unwashed pimply masses and that's the humanity we like to celebrate in this country, albeit the ugly fact of his theory being wrong. He's not a scientist, he's a thirteen year-old kid and he'll have plenty of time to learn how to improve.

> "He's not a scientist"

Ironically, the OP didn't say anything nearly so insulting.

> Panels efficiency is measured in Watts, and this kid is not going to be able to record their efficiency with a simple probe DMM.

Well, he could've just connected a 5-ohm resistor across the leads, so he would be measuring voltage under a load instead of open circuit. Then finding the power produced would be a simple application of Ohm's law.

The article was oulined here: http://news.ycombinator.com/item?id=2902684.

Here's a PDF mirror in case the cache goes down:　http://ompldr.org/vOXppeQ/solar_trees.pdf

Reply on news.ycombinator.com