Is this about the correct accuracy?

I have always wondered how accurate my setup was, in terms of clamp placement with interferance etc
My energy retailer has given me a csv of my monthly usage breaking down the days into half hour increments
From the csv, 1st July 00:00 to 31st July 23:30 shows me at 741.37 kWh
From Graph+, same period i get 753kWh

Is this as close as im going to get in terms of data accuracy?


That’s 1.6% high. IoTaWatt is usually within 1%. Lets make sure its apples and apples. Can you upload the CSV from your provider and the results of this query substituting your mains output for “total_power”:


You can send it in a PM if you prefer not to post publicly.

Attached is the providers data - i forgot i should be adding solar aswell, as that will effect import/export figures in iotawatt
adding both together they are much closer,
Alos, i get an limit exceeded messge at the day 21 - so cant see the rest of the month
Same limit exceeded when i run it against my Export

Meter Data.xlsx (40.6 KB)

Incase you want to see some other screens

Add &limit=2000

You didn’t mention solar or three-phase. You are using derived reference which can be less accurate than direct reference as any voltage deviation of phases B and C from the reference A is not considered. So I think 1.6% is probably within reasonability.

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Thanks - realised well after posting i should have mentioned solar/3-phase
If 1.6% is within reason - im happy
Thanks for confirming

The solar and three phase are not a problem per-se. it’s the derived reference. If you added 2 more VTs you should get to under 1% but that’s a lot of trouble and expense. The vast majority of three phase users use derived reference.

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Id like to do some further analysis. Could you post the complete CSV using the $limit=2000 parameter? Please post as a .CSV file or if using xlsx please import with comma delimiter so the data and Wh are separate columns.

Also, have you calibrated your VT? That alone may the bulk of the variance.

Yeah can do, Once I’m home tonight
And no, have not calibrated the VT
But can definitely look into doing that.

Attached is the csv with data for Import & Export

Meter Data-1.csv (147.0 KB)