For the sake of argument if we decide that DC in the home makes sense then the logical follow-on question is: what voltage? While there are 24, 48, and other voltage DC devices is the expectation that we would replace 120VAC (in the US) with 12VDC? For the same power we would be pushing 10x the amps which means more copper in the wiring lines, more line loss as currents go up, etc. In the end I think we would still end up with dozens of voltage changers to step up or step down voltage for our devices.
(And then there's the question of what electrical interface we should use -- are we really going to go with USC-C for power delivery despite it's inability to lock into place?)
Yes, low voltage means high current. OK for consumer devices but scary for stuff like heaters. AC is very convenient to convert to the required DC voltage, which will always vary. Switched mode adapters are light weight and efficient. Not convinced this is going anywhere.
Not a particularly useful point of reference but the International Space Station's secondary bus (that powers all the devices) is 124Vdc. Stepped down from ~160Vdc provided by solar+batteries.
Worth noting that 120Vac goes considerably higher than 120V. 120 is supposed to be the average, root mean squared. This implies to me we might be able to have lower currents if we wanted to go even higher voltage DC, without having to rewire.
One other note, usb-c defined a locking connector in 2016. There's a m2 screw 6.8mm above the flat of one side of the jack.
124VDC on the ISS: I wonder if that means that all electrical items on the ISS have to made to operate with that voltage? I don't think they would want to waste power making heat in order to change 124VDC to 12V, 6V, 9V, 20V, etc.
I'm expecting this is just the bus power to the "modules", the different sections of the ISS. I rather expect most modules probably have a down-converter & run off something like 12, 24, or perhaps the shuttle's 28Vdc.
ISS isn't afraid to waste some power. The photovoltaic arrays send power to a "sequential shunt unit", which adds resistive load to maintain a constant voltage/current from the array. Admittedly, not applicable when running off battery, but it shows that power efficiency is not really the priority.
Because you still have a lot of motors which would require inverters if the house supply was DC. Your fridge, your washing machine, your dryer, blower motors, A/C compressors, kitchen appliances, all of these require AC and a lot of power. If we switched to DC (little alone low voltage DC) all those things would need their own inverters and increase the cost of them because inverting properly is hard.
Compared to DC which can be rectified from AC by four diodes and a capacitor. It's trivial to convert AC to DC and it basically costs pennies.
There's nothing stopping you from doing this aside from regulations in some locations. Some people off grid will run heavy gauge wire throughout their house and use appliances found in mobile homes, as many of them are significantly more power efficient but cost more. They connect them to banks of AGM batteries and charge controllers connected to solar, wind and sometimes even low volume hydro. You can find hundreds of videos on youtube of people doing this. This is especially useful if you freeze some of your foods and have spotty commercial power. The battery banks and other sources will fill in the gaps where commercial power is not always available. High current DC connectors are becoming more standardized and more available on more devices as more people are turning to inverters and battery banks. Using devices designed to connect directly to batteries saves having to buy expensive inverters, sometimes.
We've gotten a lot better at high power semiconductors, and making DC into AC more efficiently with them, in just the last decade. "Fine grained Power control" is behind new heat pumps and microwave ovens and probably inductance cooktops, making them more efficient or in some cases bringing new products to market as the efficiencies finally bring them into economical possibilities.
Putting some DC bus standard in addition to AC house wiring has a lot of potential benefits but the costs and infelicities, I think, will keep it from happening. "Desk bus" standards have a lot more potential (USB obviously) but things like LED lights already want their own fancy PWM capable power supplies anyway.
I am not a power engineer. Just a curious walker by wondering about this.
As far as I can see, we have a lot of renewable energy generators (solar panels), energy storage (battery power banks), simple household electronics (lights, TV, computers etc) already prefer DC and seem to be containing converters that work hard to convert AC to DC. I get that AC is beneficial for power transmission, but why not use DC at the consumption side?
As in if all my devices were DC, I could put a bunch of solar panels and hook them up to a battery bank and supply the power needs of the house from the battery right? (without needing to convert to AC)
For renewable power: the voltage coming off of a solar or small-scale hydro system varies so it ends up being the most practical to convert that power to AC then back to the EXACT voltage DC needed for charging a battery bank (or just skipping the "back to DC" step and adding that power to a house's power source.
(And then there's the question of what electrical interface we should use -- are we really going to go with USC-C for power delivery despite it's inability to lock into place?)