Ask HN: A DC Powered Home? | Hacker News Reader

Ask HN: A DC Powered Home?

4 pointsdhosek7 comments

I’ve been thinking about the fact that contemporary home electrical wiring is heavily predicated on AC for power delivery which makes sense for power transmission as it’s been done for most of the last century or so, but with the shift to solar and battery storage, I’m wondering whether it makes sense for in-home electric wiring to move from 120V AC to 12V DC or something similar. Since I’m largely ignorant of practical electrical engineering skills, I’m wondering whether this is something that makes sense and what the engineering challenges would be. Certainly, other than my kitchen, it seems like everything in my house is converting its electricity to DC anyway (or could be easily modified to function with a DC power supply, like the lighting). And perhaps there’s no compelling reason why we need AC for the fridge, microwave, stove, toaster oven or other kitchen stuff.

View on HN

I've actually went far in planning and acquiring gear for my apartment, though it's a low priority task for me.

Turns out there are tons of stuff that sip power (set-up boxes, Ethernet switches, NAS...) that can either be powered directly by Power-over-Ethernet or through a splitter (DC-DC converter). That can be handled by a PoE Ethernet switch, which itself is usually powered at 54VDC, so it's also an excuse to run a homelab on 48VDC and get rid of tons of power supplies.

However, DC isn't well suited for the entire home for several reasons, mostly due to cheapness and historical reasons. For example, AC breakers are dirt cheap because arcs naturally extinguish when current crosses zero volts, whereas DC doesn't.

There are areas where DC is used. I work on telecommunication gear where nearly everything is -48VDC, but the beefy copper busbars needed to push large amounts of power through them would make a homeowner cry at the expense. Higher voltage is possible to compensate, but you enter not-safe-for-touch territory and I'm not knowledgeable about that.

The compelling reason is short circuits, and power ICs are cheap and good these days. With some EE knowledge, the issue is energy getting lost in house sized runs with DC.

For things like your IT closet, it does make sense to have one AC DC converter that does PoE to all of the devices, but for your kitchen it doesn't.

Your first step is to learn about amperage and wire gauge. After that you could research RVs that run on DC.

Unless we standardize on 380-400v

High voltage DC over 50 V is usually considered pretty dangerous.

Then, after researching amperage and wire gauge, pay attention to the fact that power losses in wires from the inherent resistance thereof is proportional to the square of the current passing through those wires:

https://en.wikipedia.org/wiki/Electric_power#Resistive_circu...

I’m wondering…what the engineering challenges would be

The standard engineering challenges: costs and benefits requiring engineering analysis of actual stakeholder requirements and general principles of life safety.

In this case electrical utilities, electrical equipment manufacturers, and end users are obvious stakeholders. Life safety is harder because current systems have made more than a century of dumb tax payments in the form of corpses and property loss…life safety practices come from experience not theory.

Finally, to me it looks like the low hanging fruit are being converted to DC systems that are compatible with our current infrastructure: laptops, electric cars, etc.

Reply on news.ycombinator.com