Not saving consecutive values and errors with integral calculation - incorrect power monitor

Feature Requests
1

Home Assistant, by default does not record/save consecutive sensor values.
And this leads to errors in the computation of integrals, eg template sensors to convert power (W) to (kWh) for the energy dashboard.

The attached graph illustrates this:
I have solar installed and my smart meter reports energy going into and out of the grid:
Yellow curve - grid activity, negative is export, positive is import, in W
Blue curve - template sensor filtering only positive values of grid activity (ie grig import), in W
Green curve - integral of power of blue curve, in kWh

Because consecutive 0 values of grid import (blue curve) are ignored, this creates an incorrectly large area under the blue curve from the first 0 reading to the next non zero value if the next value is large.
The reason for the consecutive 0 values is because during the day, when the sun shines, most of the time the grid import is 0 W.

Thus, the resulting integral is also incorrectly large, when in fact i should only be the area under the positive values of the yellow curve.

And for the energy dash board, this results in incorrect calculations of energy usage.

Is there a way to force the recording of consecutive same values, particularly of consecutive 0 values.

Or is this something to be reported as future fix?

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2

How are you calculating your integral?

It appears to be incorrectly decreasing when you are consuming power.

3

I agree it looks suspicious.

The integral is computed over 15 min intervals, and that value is plotted at the beginning rather than the end of the interval.

I have found a work around.

Because my smart meter only records grid activity, I have template sensors that split this into ‘grid import’ for positive values and ‘grid export’ for negative values. In the template, I add a tiny random amount when the sensor value is 0 using the following: ( range(1, 100) | random / 100000 )

This forces the recording of a value, but because it is so small it is treated as 0 for intents and purposes and therefore avoids the artefactual large areas under the curve which otherwise would be falsely computed as part of the integral.

4

Try using the Riemann Sum integral approximation integration instead:

Use method: left not the default trapezoidal.