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Comment by modeless | Hacker News Reader

So much complexity to deal with synchronizing AC frequency. I wonder if DC wouldn't be a better choice for a modern power grid?

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High-voltage DC [1] is being used to transport power over longer distances because it can be cheaper and there's less power loss.

Like a sibling commented here, the costs would be enormous to convert an AC grid into a DC grid. AFAIK are there two reasons that the grid is AC: generators produce AC, and AC is so easy to transform up and down. That transforming is essential since you want to transport energy at high voltages [2] but you don't want 380kV in someone's house.

[1]: https://en.wikipedia.org/wiki/High-voltage_direct_current [2]: https://en.wikipedia.org/wiki/Electric_power_transmission#Ad...

Your right that AC is super easy to transform. But it’s quite easy to build generators that produce DC.

They’re frequently called dynamos and you find them on old bikes to power the lights.

With modern electronics doing DC-DC transforming is pretty easy (because modern electronics is basically magic). And the reason why high voltage DC transmission is a thing, is because you can get way more power down the same wire with DC compared to AC.

Many high voltage DC lines used to be high voltage AC that was converted to increase the transmission capacity without building more cables.

But, apart form installation costs, a low voltage DC power network inside homes might make sense (e.g. 12V or 24V). There's a lot of modern electronics that doesn't depend on the regular powerline voltage anymore. Unifying their power supplies into a central unit should have some benefits.

> a low voltage DC power network inside homes might make sense (e.g. 12V or 24V).

It wouldn't work. The needed wires would be like garden hoses.

Yup, there's a reason even POE is 48 volt in a lot of applications

I recall seeing somebody that did exactly that, largely because it was way more efficient for solar setups. It is a bit ridiculous to take DC power from solar panels, convert to AC power, then plug a standard home electronic power supply into it which... converts it back to DC.

Might not work for everything (eg, refrigerator? Microwave?) but it could be worthwhile to run a secondary DC network.

It will certainly not work for devices with high power requirements. So ovens, washing machines, etc. are out. But computers, TVs, routers, phone chargers and all the other small stuff might profit.

AC also allows for smaller switches and relays, as you are guaranteed to hit 0 V within a phase, so you can disconnect loads without giant sparks/arcs.

Within half a phase. And not to nitpick, but the important part isn't that it's 0V, it's that it's 0A which isn't the same point when dealing with inductive loads.

The costs to refit would be enormous.

I think there are some issues on longer lines with things like inductance, cable size requirements, etc as well.

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