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PaperclipPerfector  1mo ago (text post)   2878 thread views

Small-Scale Question Sunday for September 15, 2024

Do you have a dumb question that you're kind of embarrassed to ask in the main thread? Is there something you're just not sure about?

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Solar panels, for charging devices(and access to a charger can be a valuable trade good if networks are operating).

Any electronics in them will be toast from a single EMP. Possibly also the panels themselves.

Keep them in a faraday cage until you need them?

If you're storing this stuff purely for use after a nuclear exchange, wouldn't you store it in a DIY Faraday cage?

You'd hope so, but I'm not sure if people realize just how much trouble that is with solar panels which aren't exactly tiny and obviously can't be used while they're in such specialized storage. You can't just wrap them in aluminium foil or similar super lightweight "protection".

Doing a bit of googling, the solar panels would probably be the highest risk since they have the longest dimensions and thus highest field strength difference from end to end.

Update: apparently tiny solar panels are, in fact, a thing. The emergency radio I bought has, in addition to its hand-crank and charging port, a ~5cm2 solar panel on it. I can't imagine it provides much power (it does have a cable to charge other things), but eh.

(Given the solar panel, I didn't even bother asking if the radio was EMP-proof; it's going in foil if/when there's a crisis.)

Doing a bit of googling, the solar panels would probably be the highest risk since they have the longest dimensions and thus highest field strength difference from end to end.

Note that size only matters here if it's the size of a conductor (i.e. metal) attached to a semiconductor, not the size of the semiconductor itself (because the semiconductor's resistance also depends on size and that cancels out).

But that's kind of irrelevant; yes, photovoltaic solar cells are low-voltage semiconductor devices (specifically, they're giant diodes) and are thus likely toast if exposed to EMP. Solar-thermal can be EMP-proof, as there's no specific need for semiconductors and metals don't really care about EMP, but AIUI solar-thermal generators are more a thing for power stations than something remotely portable.

metals don't really care about EMP,

Metals do care about EMP but only by heating from the induced currents. This is why power delivery networks are going to be toast and can have problems even from major geomagnetic storms. For shortish length and reasonably large surface area (ie. most things you're likely to have at home), it of course won't be a problem.

So really two mechanisms: field strength induced overvoltage breakdown in semiconductors and heating from high currents induced to long wires.

This is why power delivery networks are going to be toast and can have problems even from major geomagnetic storms.

It's specifically the transformers that are vulnerable to E3; the extra voltage/current buggers up the assumptions that go into their design, so they lose efficiency (efficiency at transmitting the normal power from power stations) and, yes, overheat. Of course, power grids don't work without the transformers, but the long wires themselves are in no danger (we know that one experimentally due to the Carrington event).

But yes, transformers are metal and they are vulnerable if not unplugged.

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