How Tesla Batteries Will Force Home Wiring To Go Low Voltage

CIStud writes with a story at CEPro suggesting that solar power and home batteries like Tesla's PowerWall "will force the reinvention of home wiring from primarily AC high voltage to DC home-run low voltage to reduce power conversion loss," writing "To avoid the 20% to 40% power loss when converting from DC to AC, home wiring will have to convert to home-run low-voltage, and eventually eliminate the need for high-voltage 110V electrical wiring." As a former full-time Airstream dweller, I can attest to the importance of DC appliances when dealing with batteries.

Comments

Re:Impractical

[Phreakiture]

This is largely what I was thinking.

As it currently stands, commercial buildings often have 277V lighting circuits (this is in the US) because it involves installing less copper in the ceilings.

From this, one can intuit that lowering the voltage will significantly increase the amount of copper, but let's take an example and make it more solid.

Let's say, for the sake of example, that we were considering 48V DC as an alternative to 120V AC (I personally would not want to consider anything lower than 48V in a home environment). If you need to deliver 1200W from point A to point B, it will require 10A at 120V, and 25A at 48V.

That 10A could be safely delivered on a 14 ga. wire in most domestic contexts, but will probably be delivered on 12 ga. For 25A, however, you're going to need 10 ga.*

A 250' roll of wire is ~$43 for 14 ga, $95 for 12 ga., and $138 for 10 ga. See the problem?

For the next challenge, you will also need to use different, more expensive switches and circuit breakers, or drop back to using fuses. This is because an AC arc self-quenches in half a cycle or less, and won't re-establish until the contacts are brought close enough together. The DC arc, on the other hand, is continuous, and requires additional effort to quench. Just for the record, there is an arc every time that a circuit breaker or switch is opened under load. This is the reason why you will often see switches and breakers labelled "AC Only".

Now, this is not to say that these problems won't be overcome or that a different variant might come about. Who knows? Maybe they'll gravitate towards 120V AC or some such, in which case it will be 1915** all over again.

(*For the non-Americans and uninitiated, US wire gauge is backwards: larger numbers are smaller wires. 14, 12 and 10 gauge are ~2.1, 3.3 and 5.3 mm^2, respectively)

(**There is nothing special about 1915, but I live in a house that was built in 1915 and was electified from day one. It would have had DC delivered to it in those early days, courtesy of Mr. Edison's various efforts in my current home town of Schenectady.)

Re:Will This Fight Ever End?

[TWX]

You'd think the fight between Edison and Tesla would have ended long after their deaths. Clearly not. It is a good thing their graves aren't near each other, if they were, there would surely be lighting bolts going back and forth.

I have that Thinkgeek t-shirt actually...

It is mildly amusing that DC, Edison's favorite, might be better suited to an application named after the major proponent of AC, Tesla...