Will a Solar PV Tree Offer Advantages?
The reader who asked earlier about wearable solar PV clarifies:
I agree with you that the direction for these threads for wearable power generation is a dead end or at least a very low power, niche market.
My thought has to do with using short threads, 3-5 in. in length, in very high volume to construct a “solar tree.” Nature got solar collection right long before humans ever tried. A tree gathers more light, direct and ambient, per square meter of land space than a flat panel ever will.
The trouble with PV “leaves” is the fragility and weight. You can’t build a maple tree out of thousands of small PV panels without having a high failure rate. What you CAN build is a pine tree… millions of thin needles on a conifer collects light just as much as a broad leaf tree, but with the added benefits of higher durability and weight reduction.
If these PV threads can be manufactured in the needed volume, MW scale solar trees could be possible and installed in a smaller land footprint than current solar flat panels.
Oh, I see now. And I like your analogy to the tree that nature evolved. But you need to keep in mind that nature’s task here went far beyond maximizing the absorption of solar energy. Healthy trees need good systems to pull water and nutrients out of the ground, to protect themselves from predators, to stand up in heavy winds, etc.
More importantly, you need to keep in mind the basic mathematics involved here. There is only so much power incident from the sun on a given surface of the earth, the maximum of which is ~1000 Watts/square meter. In the cases of a solar panel, this surface is normally a rectangle; in the absence of solar tracking, that rectangle is smaller in the early mornings and in the later afternoons. In the case of a Christmas-tree-shaped conifer, the surface also varies throughout the day; when the sun is overhead it’s roughly a circle, at other times it changes into a cone.
In any case, what we’re talking about is maximizing the conversion sunlight into electrical energy given the area on which the sunlight is incident, but that can never exceed the product of the efficiency of the PV itself (say, 22%) times that area. Manufacturing a fake tree will a) not change that, b) be expensive, c) be fragile, and d) throw shadows on the PV “needles” behind those facing the sun (PV doesn’t deal well with shadows).
As always, I suggest that you build one of these and conduct an experiment—an ancient concept that received heavy promotion about 2300 years ago from the great Aristotle (pictured).
