The problem is that nothing wants the same DC voltage. It wants 3.3V, or 5V, or 12V, or 48V, or 18.7V, or whatever. You end up with layers of conversion and save nothing in the end.
Let’s say you start with solar photovoltaic panels, a DC source. It feeds into a DC-DC inverter that puts out a steady 48V. Existing DC-AC microinverters can get 95% efficiency, and DC-DC conversion can be around the same.
In an AC system, we convert to DC at point of use (be it through a wall wort, a floor wort, a USB power port integrated into traditional AC plugs, or something else). This conversion can likewise be around 95% efficient.
In a DC system, we still have to do a DC-DC conversion to get the voltage you actually want at point of use. This is around 95% efficient, as well.
In the end, we stack the same number of conversions at around 95% efficiency no matter if we run AC or DC. Except that assumes we’re coming from a DC source in the first place, like solar photovoltaic. If we come from an AC source, like wind or hydro or pretty much anything besides a solar panel, then we only have transformer losses of converting the higher line AC voltage to what your house uses. Those aren’t 95% efficient; they’re closer to 98% efficient, so we’re better off.
So DC home power sounds like a good idea until you break down how conversion efficiency hits things in practice. If we’re just going to get to the same place, why bother ripping out our current system?
That said, I would like to see PoE get used for residential more. There’s lots of devices that can run off 48V and can also use networking (like smart LED lights). Why not put it over the same plug and skip having to put those devices on a wireless network? Also, you don’t need a licensed electrician to run it. You can’t be an idiot about how to run and terminate it, but you don’t need a license. This would likely be alongside our existing AC wiring, though.
ShadowRam@kbin.social 10 months ago
_ It wants 3.3V, or 5V, or 12V, or 48V, or 18.7V,
Exactly
That's why if you had a 110VDC supply at the wall, you do a simple PWM step-down to the required voltage in every device.
LOADS cheaper/efficient than any USB-C PD circuit...
Saves on transformers, saves on dozens of USB PD wall outlets, saves on communication needed to communicate the PD required between each device and every USB PD wall outlet.
Much cheaper. More efficient.
If only the wall was 100VDC instead of AC
frezik@midwest.social 10 months ago
Why would 100VDC help over AC? You lose very little by rectifying AC.
And again, these aren’t the high draw items in the house. Stuff with motors are, like air con and refrigerators. Those are better left on AC. Why bother when the gains are small?
ShadowRam@kbin.social 9 months ago
Stuff with motors are, like air con and refrigerators. Those are better left on AC.
No. Trend is they are all showing up with frequency drives. Of which those inverters are rectifying to DC before making their own AC.
Efficiency gains are massive, hence why they are doing it.
You lose very little by rectifying AC
You lose a lot actually in all the small cheap rectifiers that are in every device in the house.
Where a single purpose designed FET rectifier that is built for efficiency at the breaker would be drastically better.