Why all solar panels are secretly LEDs (and all LEDs are secretly solar panels)

Diodes are really simple electrical components.

They're designed to only allow electricity to flow in one direction, a bit like a valve.

But, because of the way we make diodes, they're capable of so much more than that.

In the mid-1900s some curiously minded scientists noted that if you push electricity through a diode (or, more formally if you apply a voltage across a diode) then it emits light, which is why LEDs are made of diodes.

They're light emitting diodes, but what's really cool is that the reverse is also true.

So if you shine light onto a diode then the diode will push electricity through itself or more formally, you will measure a voltage across a diode when light is shining onto it, which is why solar panels are also made of diodes and one neat consequence of all this is that all solar panels are LEDs and all LEDs are solar panels because they're all just diodes.

It's a bit like speakers and microphones actually.

They're just the same thing as well and you can use a speaker as a microphone So in this video you're going to see solar panels acting like LEDs and LEDs acting like solar panels and then in the next video I'm going to explain how it all works, so, how a diode works and why that means diodes are used as solar panels and LEDs.

obviously LEDs are engineered to be good the emitting light thing and actually, they're not great at being solar panels though they can be used in that way and the opposite is true for solar panels they don't make great LEDs and in fact one of the shortcomings of a solar cell as an LED is that the light they emit isn't visible.

Can you call it an LED if you can't see it? This video's a lie.

I know it was my idea.

I know there's no one there.

You can't see infrared light with the naked eye but digital cameras can.

If you look inside a digital camera you'll see that there's a filter over the sensor.

That's filtering out infrared light because actually you don't want your camera to see infrared light, you want it to see what the human eye sees.

But if you remove that filter your camera can now see infrared light and I've got one of those modified cameras so here's the camera with infrared light filtered out and here it is with the infrared filter removed and Here it is with visible light filtered out.

So it's just Infrared that you're seeing and actually look at the lining of my hoodie Things are really weird in infrared light.

By the way, it's near-infrared light, which is the infrared closest to what we can see It's not really useful for things like thermal imaging I took the solar panel out of a calculator and look what happens when I apply 14 volts across it.

I also bought some of these little solar panels.

Look what happens when I connect it to four 9-volt batteries in series.

What's interesting is if I crack the diodes inside, you can't see the cracks from the outside but if I pass a current through it and look at it through my modified camera, you can see those cracks you can actually use that method as a diagnostic tool to look for faults in your solar panels This is a concentrator photovoltaic, so it's quite niche when you pass electricity through it it produces visible light Now for completeness here's an LED producing a voltage when light shines on it in other words acting like a solar panel For an explanation of how diodes work and why all diodes are solar panels and LEDs at the same time Look out for my next video or even better Click Subscribe if you super want to make sure that you catch that video also click the notification bell.

I really like the story of the diode because it illustrates how a healthy dose of curiosity in the workplace can lead to world changing innovations.

I like to make sure that my work environment is conducive to curiosity by having all my previous projects easily to hand so that I could combine them in new and novel ways but what about your workplace in a 2018 state of curiosity report conducted by Merck just 20% of participating employees described themselves as curious Yeah, 80% of participants said that curious colleagues would be more likely to bring an idea to life at work Check out the 2018 state of curiosity report for yourself and find out what's stopping you from being curious at work Thanks for Timothy Silverman and for giving me the idea for this video And for helping me out with some of the concepts and thank you to my patrons and patreon.

I'll see you next time.

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