Properly computing the net kWh
Posted: Wed Dec 21, 2022 1:01 am
I installed a V.3 meter at my house and am extracting the NET kWh to graph as my solar system pushes power out and as my house consumes power.
The meter has a "Total kWh" register and a "Reverse kWh" register.
Based on the definitions at "https://help.ekmmetering.com/support/so ... data-terms", the Total kWh register is the SUM of the Forward and Reverse kWh, e.g. Total kWh = abs(Forward kWH) + abs(Reverse kWh), whereas the Reverse kWh is only the power in the reverse direction.
To get the Net kWh, I am using the following formula from the above link: Net kWh = Total kWH - (2 x Reverse kWh)
Is this the correct way to calculate the net kWh?
I'm seeing data that looks about right but I have no idea if it is actually correct.
I ask this because I just installed another V.3 meter on a travel trailer hookup that should never see reverse power. I'm using the same data gathering script and I am observing the reverse readings slowly increasing over time. This particularly stands out when power consumption is very small.
The meter is sampled every five minutes.
For example, at 09:50, the Total kwh was 63.6 and the reverse was 10.4
Then at 09:55, the Total kwh was 63.7 and the reverse was 10.5
The next read, at 10:00 was 63.8 and 10.5
This translated to reporting 100wH in the reverse direction during the first period and 0wH total in both periods during a period of time that the long term reported load was about 200 watts. (I will try to check the load with a clamp-on but it can be tricky if loads are not consistent.)
I noted that by 18:00 today the Total kWh had reached 68.7 and the Reverse was at 11.0.
I guess another question would be "Is it normal/expected for there to be this amount of drift in the reverse reading?" Basically 500wH over a period of 12 hours or about 40 watts.
The meter has a "Total kWh" register and a "Reverse kWh" register.
Based on the definitions at "https://help.ekmmetering.com/support/so ... data-terms", the Total kWh register is the SUM of the Forward and Reverse kWh, e.g. Total kWh = abs(Forward kWH) + abs(Reverse kWh), whereas the Reverse kWh is only the power in the reverse direction.
To get the Net kWh, I am using the following formula from the above link: Net kWh = Total kWH - (2 x Reverse kWh)
Is this the correct way to calculate the net kWh?
I'm seeing data that looks about right but I have no idea if it is actually correct.
I ask this because I just installed another V.3 meter on a travel trailer hookup that should never see reverse power. I'm using the same data gathering script and I am observing the reverse readings slowly increasing over time. This particularly stands out when power consumption is very small.
The meter is sampled every five minutes.
For example, at 09:50, the Total kwh was 63.6 and the reverse was 10.4
Then at 09:55, the Total kwh was 63.7 and the reverse was 10.5
The next read, at 10:00 was 63.8 and 10.5
This translated to reporting 100wH in the reverse direction during the first period and 0wH total in both periods during a period of time that the long term reported load was about 200 watts. (I will try to check the load with a clamp-on but it can be tricky if loads are not consistent.)
I noted that by 18:00 today the Total kWh had reached 68.7 and the Reverse was at 11.0.
I guess another question would be "Is it normal/expected for there to be this amount of drift in the reverse reading?" Basically 500wH over a period of 12 hours or about 40 watts.