Same here. The problem is that there's no consensus on what voltages. I might prefer 48v for lower losses but you might want 24v since it's "safer" and my neighbor might want 192v since he's already an electrician.

There are multiple things that we really need to make it viable. A standard for the plug that separates it from any AC standard, a standard voltage and current and then standard DC to DC convertors for adjusting the voltage. I guess also we need a completely different light bulb fitting socket too that only fits DC light bulbs. Lots of different commercial DC convertors of varying sizes to replace the AC convertors in all sorts of devices.

I do wonder how much in practice would be gained given the DC to DC conversions are guaranteed for every device.

When I built out a van into an RV, I got to run a new electrical system for it — one based around the 12V automotive battery.

It turns out that there is a small industry out there that serves both RVs (and boats as well) that is 12V/DC based. Lights, pumps, refrigerators, fans, all running straight off a 12V power bank. "Cigarette lighter" outlets stand in for wall outlets for USB-style chargers, etc.

The 12V/DC battery system in the van is of course charged from both solar on the roof of the van and from the van's alternator (when the van battery is topped off and the van is under power of course).

I did add an inverter to supply 110V/AC for a pair of traditional electrical outlets I installed in the kitchen area of the van/RV. These are primarily used for plugging in wall-wart style chargers for the laptops.

(My Kill-A-Watt suggests that my rice cooker and even the electrical kettle would, just barely, function on the current provided by the inverter but RV-life tends toward minimalism so those extra appliances I've left behind.)

In any event, the whole experience did have me wondering if I could run a parallel 12V/DC electrical system in a new home and do away with a lot of the step-up/down of AC.

Definitely could do with some kind of modern outlet (USBC?) rather than the cigarette lighter outlets, ha ha.

What would be nice is a residential power over Ethernet standard. With standard crimp connections.

Some advantages power limited and low voltage means it's safer[1]. Ethernet means you can control lights and other devices. Smaller diameter wiring means it's cheaper. Not needing a licensed electrician to install it saves $$$.

[1] Can imagine for a non North American not having to deal with 230VAC would be a big bonus.

What would make the most sense to repurpose AC wiring for DC. The big problem is that only circuit goes to each spot and putting in duplicate circuits would be expensive.

The standard AC wiring is probably enough for 720W with 48V. The problem with choosing 48V is lock to medium power. Appliances would require 240V or 480VDC to get enough power.

The big problem is that there is no standard for DC power outlets or plugs. Would need to be different from AC and would also need to be different for different voltages.

You could use USB wall sockets :)

There's already a somewhat common standard for DC wiring in homes and offices, though it's probably not exactly what you had in mind: it's Power over Ethernet (PoE), which provides around 48V over standard twisted pair Ethernet wiring, while still allowing it to be used for data.

Power over Ethernet perhaps?