I say this, because I was guilty of this exact shortcut thinking (in another comment). But I paused and thought to myself "I should run the numbers before just repeating the usual voltage drop criticism".
So I compared scenarios and it depends a lot on the topology, lengths, costs, and situation (new vs renovation).
Sure, a whole house system doesn't typically make sense, but I don't think that's what people are really talking about. I think people are interested in hybrid systems; e.g. DC power supply for each room.
I don't know if you meant it, but the sentence about "any sophomore level electrical engineering student can solve this" can easily come across as dismissive. I also think it gives too much credit to sophomore students. :)
I would have more confidence in an electrician apprentice on this one. I think they'd have more practical experience when it comes to figuring out what are the right questions to ask.
I did EE in college and do a fair bit of hands on residential electrical work.
P.S. How many sophomore level engineering students learn to do a sensitivity analysis?
I completely disagree. Where exactly are you going to put a power supply in a room? Make a special electrical box for it? Won't it be unsightly in many rooms, or need some huge special panel that looks like a breaker panel? The comments I see seem to be advocating a whole-house solution, where a power supply is mounted in the breaker panel to supply LVDC to the whole unit. But this makes no sense for several reasons, especially the voltage drop.
>I don't know if you meant it, but the sentence about "any sophomore level electrical engineering student can solve this" can easily come across as dismissive. I also think it gives too much credit to sophomore students. :)
It's supposed to be dismissive, because this whole discussion is a bunch of software people trying to make up solutions for a perceived problem when they obviously don't know one of the most basic things about electrical theory, which makes all of their solutions unworkable. It's like a bunch of people trying to make a new kind of personal vehicle to replace cars when they don't even understand Newton's Laws. It's really annoying, because I see this kind of discussion pop up every so often, over many many years.
I have another comment here I don't feel like copy-and-pasting, but basically this whole discussion is silly because people are trying to make a solution using a very expensive power supply to fix a problem they see because they're buying cheap $2 light bulbs that burn out quickly, instead of just buying light fixtures that were properly engineered in the first place. With modern SMPSs, you're not going to get any kind of benefit by centralizing the power supply to drive individual LEDs, you're only going to get problems. LEDs need a driver circuit to provide constant current, and that means the power supply needs to be matched to the emitters and kept very close to it.
Switched-mode power supplies can be as small as your average Arduino board. They can fit inside the space used for wall outlets or light fixtures. Or you can put the DC transformer inside the light switch.
This sounds like a non-issue, specially considering the pervasive use of "unsightly" installations like air ducts, heating vents, radiators, electrical sockets, telecommunication service panels, routers, and even light fixtures.
If you intentionally dismiss obvious solutions, of course you only end up with problems without obvious solutions.
> It's supposed to be dismissive, because this whole discussion is (...)
If you have nothing to add, please add nothing.
It's not about DC vs AC, it's high-voltage vs low-voltage. The power dissipation by wire resistance scales with the square of the current ($P=RI^2$), and low line voltage means that you need large currents to transmit the same amount of power.
But what about the sub 100W or even 200W applications? That's where I think something like 48VDC would start to shine. Every light in a home, phone chargers, tablet chargers, computer monitors, televisions, computers? (maybe not gaming rigs, but certainly laptops and nucs).
How so? Exactly what benefit does it have over the current AC mains? With 48VDC, you'd still need to use DC-to-DC converters to power everything. I fail to see how that's any kind of improvement over the current switch-mode power supplies used. Instead, it'll just be less efficient because you'll get higher line losses in the power lines in the walls and all the way from wherever that 48VDC is coming from. If that's from a big SMPS in a closet somewhere, that's going to have its own losses. Overall, the entire system will have lower efficiency compared to the current system.
Exactly what problem are you trying to solve with this idea? If you think you're going to eliminate SMPSs in all your electronic equipment, you're not; that's a fantasy. Everything needs a power supply because electronics only work at very low voltages (5V, 3.3V, even 1.8V in places, now 20V with USB3) and most equipment has some kind of peculiar voltage requirements, and usually multiple different requirements inside the same device. There's no improvement in efficiency by running a computer, for instance, from 48VDC vs. 120VAC or 240VAC, in fact it's probably worse.
Also, DC and AC have differences in power transmission independent of resistance, some due to first principles (reactivity), and others related to devices for stepping voltage up or down (eg transformers).
