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jfleissner avatar image
jfleissner asked

Wrong values on VRM for solar production with KACO grid-tied inverter

Hi!

We currently have one installation where we experience a systematic (-) offset of the value of solar production on the VRM. Our customer has noticed himself and we could verify, since we also log most of the values to our own database: the value of daily solar production on the VRM is off by between 8 and sometimes almost 30%.

It seems as if for the values on the VRM not the actual inverter registers ("ETD") are used, but the systems sums the power up and puts this into VRM.

If I remember right, one basic rule of Victron says: if there is an energy-register: use this register as opposed to "summing up", this improves accuracy.


Configuration is as follows:

  • ESS with
  • CerboGX,
  • Kaco blueplanet 15.0 nx3 m2 on AC in of
  • Multiplus II.
  • EM540 to measure grid and some batteries on the Multiplus II.

This is, for us, a very common configuration that now gives us a lot of headaches at this one installation.


One problem of the Kaco blueplanet nx my inverters is the sometimes low performing wifi-dongle. It loses connection every once in a while an behaves oddly - we usually tie it to the Cerbo's hotspot and this has improved overall performance to an acceptable level.


Does anyone have an idea or any possibility to check? Can anyone/ did anyone analyze the data thats getting sent to the VRM?


Any help much appreciated!


Johannes

ESSvrm bugsunspec
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1 Answer
desertfox avatar image
desertfox answered ·

Hello Johannes,

i'm currently not able to supply any solution yet but i do have the same strange problems.

Some days my solar production is on par with the values of my 2 Kaco 8.0 NX3 M2 and some days im off like 50%.

The Rootcause looks like VRM is calculating the solar production values instead of using the supplied values via modbus.

We do have 2 idencital installations here:

- Kaco 8.0 NX3M2

- Cerbo GX running v3.41 stable release

- Multiplus II 5000

I've already changed the wifi setup from mesh to a seperate pv-exclusive Wifi. The AP is around 2-3m away from my kacos. this improved the wifistability massivly because the Kaco WiFi Stick does not support mesh-streering.


But still...VRM shows different "calculated" pv production values.

Kaco supplies via Modbus the correct values, so VRM should use these instead of alculating it.


Hope we will find a solution in the next venusos patch


regards Florian

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