I've had a couple of WiFi outages lately (not Iammeter related) and discovered missing data once reconnected.
Home Assistant showed totals once reconnected that looked correct, so the meter was obviously still tracking the total kWh data. I know HA doesn't backfill data, but I was surprised seeing Iammeter dashboard didn't.
Exporting the CSV using 'History Record' shows data missing. Is this expected behaviour or is there a buffer not configured?
|Voltage(V)||Current(A)||Power(W)||Grid Consumption(kWh)||Exported Energy(kWh)|
1 Both single-phase energy meters (WEM3080) and three-phase energy meter (WEM3080T) do not have internal storage.So if the Wi-Fi network is down, the instant data would be lost.So you will not see the historical record of voltage, current and active power at the time when the network is down.
2 But the kwh data is accumulative in the energy meter,it will not be affected by the network.
the network is down at 1:01 and recovers at 1:59.
the load is a constant (5kw)
Then you will lose the instant data from 1:01 to 1:59, but the kwh is accumulative all the time(if the energy meter is power on), so if the kwh is 100kwh at 1:01, it will report 105kwh(nearly,not exactly) at 1:59 (when the network is resumed).
It will also lose the historical record of the kwh during 1:01 to 1:59.
But if you want to calculate the hourly energy data ,you do not need to know every kwh data in the hour ,you just need to know the first and last data.
As far as I know, the home assistant also uses the first and last date to calculate the hourly energy data.
By the way, the first may not xx:01 and the last also may not the xx:59. the Home assistant just uses the first data and last data it can be found in one hour to calculate the hourly energy data).
The same logic is in the daily, monthly energy data calculation.
This explains why the network outage does not affect the hourly energy data calculation.
Thank you for the comprehensive answer.
You're correct in that it isn't overly important for energy consumption overall since the main factor is the totalising, however it could become important if crossing a tariff time barrier or looking for events that have occurred during the time missed.
Home Assistant is quite rudimentary in this area and from what I can gather does not utilise timestamps so would have been missed regardless of buffer or not. It's great for an overall view but lacks many of features of more dedicated systems.
Please consider incorporating a limited logging capability in future products. Even a small buffer may be sufficient to trace events that could point to the cause of an outage (e.g. poorly filtered appliance turning on)
thanks for your suggestion.
I will forward this suggestion to our products department.