Cybertruck - How Much THD?

[Jager]

As I mentioned in another thread, we had a utility power outage this morning. I powered our home for the first time using the Cybertruck.

Once utility power was restored, I took advantage of having both power sources in close proximity to measure how much THD the Cybertruck's outbound power (vehicle-to-home) produces.

I won't belabor THD (Total Harmonic Distortion) too much, other than to say that it's an important and often overlooked (by consumers) quality measure. Especially in today's world where the devices we power increasingly include a microprocessor element.

In a nutshell, THD is a percentage measure of how much the power you're receiving deviates from a perfect sine wave. Very low levels of THD would indicate "clean power." Very high levels would indicate "dirty power."

For context, IEEE 519 recommends 0-8% for public utilities. Dirty power will shorten the life of pretty much every kind of load it energizes, and especially sensitive equipment may fail to operate at all.

Upon restoration this morning, my local utility (Dominion Power of Virginia) measured:
123v
60.00 Hz
1.7% THD
Really excellent numbers.

My Cybertruck measured:
121.1v
59.99 Hz
2.8% THD
Also really quite excellent numbers.

I've long expected that the Cybertruck would probably produce very clean power. But the CT still has to invert the DC in its pack back into AC. So it wasn't a given.

Feel free to power all your sensitive stuff with it!

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[CyberGus]

In a nutshell, THD is a percentage measure of how much the power you're receiving deviates

I prefer “THC”

 

[REM]

excellent numbers! thanks for the report!

 

[Feathermerchant]

I tend to disagree that THD is super important because
A) The electronics I have looked at like PC power supplies and other consumer electronics has filtering on the input.
B) The components after the filter consist of a bridge rectifier to convert the AC to DC then a large filter capacitor to reduce the ripple. So THD in the AC sine wave should not matter much.
C) Induction motors can produce more heat when run with high THD. You'll find them in your AC compressor and indoor fan motor. Unless they are variable frequency/speed then they have a variable frequency inverter that starts with DC like out Teslas.

I'll also point out that the grid is powered by VERY LARGE (~1,000MW) rotating generators which have very low impedance and so can absorb a lot of THD.

 

[Jedi2155]

As I mentioned in another thread, we had a utility power outage this morning. I powered our home for the first time using the Cybertruck.

Once utility power was restored, I took advantage of having both power sources in close proximity to measure how much THD the Cybertruck's outbound power (vehicle-to-home) produces.

I won't belabor THD (Total Harmonic Distortion) too much, other than to say that it's an important and often overlooked (by consumers) quality measure. Especially in today's world where the devices we power increasingly include a microprocessor element.

In a nutshell, THD is a percentage measure of how much the power you're receiving deviates from a perfect sine wave. Very low levels of THD would indicate "clean power." Very high levels would indicate "dirty power."

For context, IEEE 519 recommends 0-8% for public utilities. Dirty power will shorten the life of pretty much every kind of load it energizes, and especially sensitive equipment may fail to operate at all.

Upon restoration this morning, my local utility (Dominion Power of Virginia) measured:
123v
60.00 Hz
1.7% THD
Really excellent numbers.

My Cybertruck measured:
121.1v
59.99 Hz
2.8% THD
Also really quite excellent numbers.

I've long expected that the Cybertruck would probably produce very clean power. But the CT still has to invert the DC in its pack back into AC. So it wasn't a given.

Feel free to power all your sensitive stuff with it!

2.8% THD isn't that great to be honest as a decent solar inverter would normally be less than 1.5% . Also I'm assuming you're referencing voltage THD, since typically you want to use TDD (Total Demand Distortion) if you're referencing IEEE 519 especially under load. I'd be more interested in understanding how good the distortion is in higher order harmonics since that may be more impactful when you're dealing with inverter based resources.

When using IEEE 519, you need to take into account the Isc vs IL ratios for the THD / TDD numbers to really make sense.

 

[Jager]

Dunno that I'd compare grid power (or Cybertruck power) to what you'd get from a solar inverter. Not many people have solar.

The context here is when grid power goes dark. For most of us, that comes down to some kind of ICE generator; or, now, for some of us, vehicle-to-home.

Most conventional (non-inverter) ICE generators produce really ugly power. But the fellow who just spent $300 on his made-in-China genset doesn't want to hear that the stuff in his home will fare any differently on that than the several-thousand-dollar Honda inverter model someone recommended to him. I mean, it's making the right voltage, right? And my stuff turns on, right?

Must be all that good filtering!

Grid power from most utilities in the United States is really quite good - most of the time. But the grid is affected by many things. Voltage fluctuations happen continually, throughout the day. Frequency excursions are less common, but still a thing. And the resultant THD quality - and that's all THD is, a measure of quality - ebbs and flows.

Inevitably, there are hot spots of "less good" power coming from the grid.

Chicago:

Denver:

New Jersey:

Florida:

Some challenged utilities:

The THD bogey for utilities was 5% for a very long time. Most utilities still hit that measure, most of the time.

Broadly speaking, grid power is quite good. For me, simply wondering how to respond to an episodic utility outage, that's the reference.

And for that, the Cybertruck compares very favorably. It'll be my new go-to.

 

[AlmostHuman]

Nerds. Love this thread! Thanks for starting it and all the replies. All my friends make fun of me for saying bad power causes so many issues

 

[Jedi2155]

Thanks for those detailed THD charts around the US. I was a bit of a power quality nerd early in my career. You're absolutely right that THD on traditional gensets are horrifying, and any decent inverter based system is going to be miles beyond it with the CT being no exception.

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