How to sum the value from the electric meter and manually


I believe that this case has not been discussed here yet and that it will help more people in the future.

I have a 3P power meter installed via Tuya. Specifically through the meter cores. It’s giving me a kWh rating.
Now I have e.g. 7,6kWh value, which was measured by this meter and sent to HA.

But there is of course a larger value on my physical meter from the energy supplier that I cannot “get” into the HA.

So the question is, can I e.g. create a virtual sensor with the value from the physical meter and use the sum using Utility Meter or maybe via Reimann sum or Node red and create a fixed value file and add this value with the value from the smart meter ?

In short: I would like to know in my HA in the Energy tab, the real consumption that will be synchronized with the supplier’s meter

Probably no. You can get really close, buy that I mean at least 95% accuracy but it will be very hard to get 100 %.
For a few percent you will have to go extra miles and the question is … Is it worth it?
If it is worth it for you, there are some projects you can find online using esphome, cameras, all sort of things to get consumption as accurate as possible.

Only installed last week but it looks like my IoTaWatt will be tracking my energy use within about 0.5%.

Alternatively if you do not want to buy new hardware you can feed your energy sensor to a utility meter:

You can use the calibrate service to correct this value periodically.

This looks good.
Can you describe how to set it up via configuration.yaml and then possibly other settings to make it all work ?

All of the options are described in the documentation I linked to, as is the service for calibration.