Aeotec HEM.G2?: How to interpret the numbers

I bought a House Energy Meter on sale awhile back (thanks for the heads up @TheKorn) and just now got around to installing it. After a bit of a problem that a restart of OH solved I’m getting values for all the channels.

My problem is I don’t know how to interpret the numbers.

I understand the kWh channels and expect it continues to count up until reset though the reset channel.

I interpret the watts channel to represent the current instantaneous watts consumption (over some small period of time, or is this the derivative of kWh for an instant in time?)

But what is Power? It is a value that is always really close to but a little off from the watts channel.

I’m a computer scientist, not an electrician or electronics engineer and it had been over a decade since I’ve looked at this sort of thing. Nothing I remember and nothing I’m finding through Google is helping me figure out that value.


KWh is cumulative energy used. Goes up until reset.

Watts is the real portion of power.

For watts vs. power, you’re bumping into the difference between Watts and Volt-Amps. For certain types of loads (incandescent lights), they’re the same thing. For other loads (motors motors motors!) they can be very different.

That’s the thousand-mile-up answer, without going into any of the hows & whys. For a mere hundred-mile-up answer, see . After that, the math get… complex. :rofl:

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So the tl;Dr is use kWh to see what my power company is going to charge me this month and if I want to do something like apply FFT to see if the dryer is running use Power.

Though for actual practical purposes I can use either power, which is VA, or watts as a measure of how much instantaneous power draw is happening to see when stuff is on and how much per they are using.

I think knowing that Power is VA is the clue I needed. Many thanks!

Yeah! In fact, that’s exactly what I was doing here!

What? The data is nowhere near in high enough resolution for a FFT to do much of anything here. (Several orders of magnitude too low sampling frequency!)


I know. That was more tongue in cheek. I should have used an emoji.

Very funny indeed!!!

Good link, by the way