Hello,
I want to connect an EM540 meter and ET112 parallel on the same RS485 bus with changed addresses.
The refresh rate of the ET112 is 750ms and the refresh rate of the EM540 is 100ms.
Is this supported in the Multiplus II GX to read out the EM540 @100ms and the ET112 @750ms or will this refresh rate be limited to the slowest device?
Also, I’m replacing my old ET340 grid meter because apparantly the refresh rate of 1000ms is too slow for accurate control of the ESS. Is the EM540 the best choice for replacement?
To dubbelcheck, do you think it’s possible that a ‘slow’ meter like the ET340 can cause the ESS to poorly regulate the setpoint and thus lose a decent amount of energy to the grid instead of the battery or direct use?
I used to have a et340 and now a em540 on my 3phase multiplus 2 ess, both worked fine for me
it is faster, you cant see that on vrm but in remote console its visible, response from the system is faster too but it will always balance on grid and ise power feom grid
Okay I will order an EM540 an check the results.
I’m primarily scared that the parallel ET112 will interfere with the refresh rate.
The setpoint on the screenshot is 10W.
Currently I’ve increased to 50W and this clearly helps a bit.
In another installation I use the VM-3P75CT with a 10W setpoint and I have <1% ‘loss’ of solar power to the grid. This got me thinking that the refresh rate could be the issue.
Just as a data point: I’m currently using the grid operator’s smart meter as my grid meter, which gives me readings very 5 seconds via MQTT, and with a grid setpoint of -10W my “solar to grid” is at those 10Wh every hour, even with changing lighting and the corresponding fluctuations in PV production (that number is the same in VRM and the smart meter).
So while I see the expected slow regulation of load spikes, it seems your high numbers are not necessarily related to the meter’s update speed…
Okay interesting !
Do you have any other ideas then?
I have a very similar installation with a VM-3P75CT and sunny boy over ethernet as only differences. There I the system can manage the 10W setpoint quite well.
As the meters are the only difference, that’s my main suspect
I think I have narrowed down the problem.
The difference between the two installations I have is that one is using the VM-3P75CT and the other one is using the ET340.
The difference between the two meters is their vector registration way of measuring (see documentation).
So while the grid setpoint was 10W, there was a consumer on L3 and thus the solar panels were injecting on L1 to keep the setpoint 10W.
On the VM-3P75CT installation, this energy was recorded as ‘solar-to-direct-use’.
On the ET340 installation on the otherhand, this energy was recorded as ‘grid-to-direct-use’ and ‘solar-to-grid’.
Only consumers on L1 were recorded (as I would expect) as ‘solar-to-direct use’.
I’m 90% confident that this is the issue. This also explains why @cmock has a working system with a ‘slow meter’ as the measuring speed is not the source of the problem.
I will update after the weekend.
