Solar panels under another star

Would a solar panel work if you took it to another star system and set up at the equivalent distance? The short answer is yes. The interesting answer is that “solar energy” isn’t quite one uniform thing.

Every star fuses and radiates across a broad electromagnetic spectrum, so there’s always light to convert. But a star’s color, where its emission peaks, is set by its surface temperature, which is what its spectral class encodes. The OBAFGKM sequence runs from hot blue O-types, through our yellow G-type Sun, down to cool red M-dwarfs, and the blackbody peak slides from the ultraviolet toward the infrared as you move along it.¹1 Worth noting our Sun is a fairly small, middling star, a G dwarf. The galaxy is dominated by the cooler, redder M-dwarfs, where a silicon panel would do relatively poorly.

That matters because a solar cell is not a neutral light-bucket. It’s a picky eater. A semiconductor only converts photons above its bandgap energy. Light below the gap is lost as heat, and light far above the gap wastes its excess. Silicon’s bandgap happens to be a decent match for the Sun’s spectrum. Move that same silicon panel to a hot blue star and much of the energy arrives as high-energy photons whose surplus is thrown away. Move it to a red dwarf and much of the light falls below the gap and does nothing at all, photons knocking politely on a door the silicon won’t open. The panel still produces power either way, just inefficiently.

So the honest version is that solar power generalizes but optimal panel design doesn’t. Around a different star you’d want a different bandgap, a different semiconductor, tuned to that star’s peak. Same physics, a different material per sun.