As of this date, I have had my mains connected for 117 days. On the very first day I recorded my electrical meter reading. At present when I retrieve the sum of my iotaWatt main(s) add it to the initial meter reading I am off by a “whopping” 24kwh (75kWh/year or $13 out of $3000+ per year 
) from the electric meter reading.
As an experiment I created an adjusted Mains Output which corrects this minor difference. The output looks like:
(Main1 + Main2) x 0.99487
Sorry for being so anal about such minor issue but I am very curious on the correct way one would make adjustments tiotawatts readings. Is what I have the best way or does iotawatt provide another method?
First let me point out that’s 0.5% difference. Your meter is probably rated to 0.5% accuracy, so it’s not cl;ear whether it’s the IoTaWatt or the meter that is off. That said, the meter is what you get billed for, and so that is the standard.
The output that you define should yield the desired result, for the 117 day calibration period. There is no certainty that it will be the same for the next 117 days, or that the variation week to week during that 117 days would be consistent. It is the average. Both the meter and the IoTaWatt will have different error depending on the voltage, load and power factor from minute top minute. It’s not an exact science. At the end of the day, if you end up with a +/- 0.5% variation you are doing pretty well.
2 Likes