What does Wattson purport to measure?

Sterlingtimes

Wattson indicates grid import and grid export kWh.

My Smart Meter measures indicate:

[1] Active total import (fundamental and harmonic) kWh

[2] Active total export (fundamental and harmonic) kWh

[3] Reactive import kVARh

[4] Reactive export kVARh

[5] Test import

[6] Test export

Figures cumulative over approximately two days are as follows:

[1] 8.4 kWh

[2] 12.2 kWh

[3] 6.0 kVARh

[4] 3.3 kVARh

[5] 8.454 kWh

[6] 12.252 kWh

Is Wattson purporting to measure [1] and [2]? It is difficult to correlate.

Presumably [1] is the measure upon which I pay for my electricity.

GreenBo

I don't know if this helps, but when I was looking into which energy monitor to go with about 6 months back I stayed away from the Wattson because it assumes a static voltage (240v I think) and a static Power Factor (from memory I think it was 1). Which would result in inaccuracies of about 10% compared to a proper utility meter. It was the same for most of the other energy monitors I looked at (e.g. Owl, Geo etc). The only one that measured as accurate as a utility meter was the Smappee, which was the one I went with in the end.

I think the power formula is this: Watts = amps x volts x power factor (maybe someone who's an electrician can verify this is correct)

Monitors that don't measure the volts and Power factor of a home will be inherently inaccurate. My Smappee is currently telling me my home has a power factor of 0.86 and the voltage is 233v, but even that varies all the time, amps are 1.272. My home is currently using 255watts. If I had a Wattson at the moment that would be showing me 305watts :eek: which is about 20% out.

You can see now why I opted for the Smappee now, measuring the volts and power factor is critical.

I don't know if this helps with your question but it's certainly worth knowing if you're trying to compare the readings from your Wattson to your meter - they just won't match.

Sterlingtimes

Now I can read accurate figures, I now know how the Wattson deviates from accurate measurements.



But much depends upon how and where the sensors are placed.