Scientists generate electricity from shadows

Originally published at: https://boingboing.net/2020/06/09/scientists-generate-electricit.html

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Our SEG performs 200% better than that of commercial silicon solar cells under the effects of shadows.

I’m not sure “working better than something light-powered in the dark” is a particularly high bar.

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So… it would have to be able to move with the sun to be useful? Hmm. And it doesn’t store energy if it’s entirely in sunlight? Hmm again.

I mean, I guess it has a purpose or they wouldn’t have pursued it so hard, but I’m having trouble imagining what that purpose would be. I suppose that’s part of why I’m not a scientist.

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why not put the shadow-powered part on the bottom side?

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Solar panels in solar farms create shadows themselves (they also commonly change angle to maintain optimum angle to the sun). So if this type of cell is truly more efficient, you could design solar farms to intentionally overlap panels to create areas of shadow on each other (as well as use the space more efficiently).

It wasn’t clear from the abstract what the scale of the cells are. If they are the size of conventional panels, then that’s cool. If the individual cells that require light and shadow are small, then the structure would have to be built into the panel design.

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Is there a perpetual motion or free energy device involved as well?

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It’s still solar. It’s not like the little white-and-black solar windmills are “free energy devices.”

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I was thinking it had to be something akin to this device you linked a picture to. The energy has to come from somewhere.

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Finally somebody found a use for those good-for-nothing eclipses!

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Stay out of the shadows!

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A coin cell can also power a basic quartz watch for several years in complete shadow.

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Hey, you’re blocking my light. :stuck_out_tongue:

^ this. The whole partial shadow thing is a distraction if we’re comparing to regular PV panels. Making shadows is the easiest thing in the world, what matters is collection efficiency.

I found the paper and in my VERY cursory look they’re suggesting using this technology for low-light energy harvesting in challenging circumstances, and for sensors; which makes me think straight away that the researchers have some reason they don’t think it’s viable as a direct competitor to current PV technology, but anyway let’s look at the money figure, collection efficiency.

Paper says: “Without any optimization, our generator has a power density of 0.14 μW/cm^2 under indoor conditions 0.001 sun”

1 sun is about 1kW/m^2. So 0.001 sun is 1W/m^2, which is 100μW/cm^2 (100^2 cm^2 in every m^2).

That makes this technology 0.14% efficient which is about 100x worse than current top-of-the-line PV panels which are in the 10-20% range right now. So, yeah, the reason is almost certainly collection efficiency. It’s an interesting effect but not about to take the world by storm.

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You’ll probably get about as much energy from a solar windmill like that, too.

This is what made me look into heliostats years ago. Not sure what the reverse of this would be, or if this approach was cost-effective though:

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Maybe bands of SEGs could be wrapped around spacecraft, using the sunlight/shadow to provide juice for the ship.

because then you just have the same issue current solar cells have, i.e. you need to have full sunlight for it to work.

my question is, does this work on cloudy days, or does it need to be half in full on sunshine, and half in shadow. if cloud coverage is considered 50% sunshine, then i can see a use for it in places like pittsburgh where is is always crappy out.

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Scientists generate electricity from energy differential between bright sunlight and shadows

FTFY

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If you really can get electricity from shade, RuPaul’s gonna be a goddamned power plant.

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P.S. Now I want a solar powered Rubik’s cube.