eli5: Do solar panels only work with sunlight, or can they be tuned to capture energy from other wavelengths outside the visible spectrum?
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The original solar panels did this – they were essentially water pipes that absorbed heat (ie IR radiation) from the sun, and fed into your hot water tank. Photovoltaic solar panels (ones that generate electricity) work by exactly matching the incoming photons to specific energy gaps in the material, meaning they can excite electrons by exactly the right amount. So in principle I guess you could try and find/design material that would work for IR or UV, such things probably already exist, but the issue is that the sun puts out the most energy at visible light wavelengths (possibly why we evolved to be able to see it and not other wavelengths). So if you’re going to use something to soak up as much sunlight energy as possible, it’s best to have it capturing the visible light. I think there are some panels which stack a few different materials to get a wider spectrum of absorption, but it gets difficult and expensive to do that I think, not least because you need the first layer to be transparent to what the second layer is trying to get power from.
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