Electromagnetic or electrical issue caused by inverter

I have a heat pump that has displayed some random issues for a while and I’ve not being able to figure out why … until may be now …
I have an EasySolar 5K in a parallel setup with an external CT where the house is on AC-out and the heat pump on AC-in
I’ve just been able to reproduce an issue where the soft starter on the heat pump detects an alarm when I switch on a load e.g. the oven.
That’s causing problem because it stays in alarm mode for 5” and won’t start the compressor causing an incident on the heat pump.

I’ve done some tests

  • charger only - Not causing issue
  • limiting the inverter to 1K - still causing the issue

Has someone experienced such interference?
Now how do I figure out

  • if it’s electrical or electromagnetic interference?
  • if the EasySolar is the cause or the Emerson starter too sensitive?

If Victron says nothing wrong with our equipment the issue is with the heat pump and the other side says nothing wrong with us the issue is with inverter how do I get out of this situation and find a solution?

I assume theres also the grid on ACin?

Which alarm does the softstarter give you exactly? Is this an ESS?

Yes that’s my parallel set up so both AC-in and Heat pump are on grid and the CT is before on the grid line.
ESS no injection. I’ve changed the set point from 25W to 50W but to no effect.
The Emerson is a CSS-32U
And whilst the heat pump is idle, if a load on my house comes in at around 1kW it will light a red led and the green will blink meaning:
Message: Motor connection error
Remarks: check wiring of R, RC and S terminals
If the load is switched off, after a delay of 5” the alarm disappears
I’ve now done several tests today and so far it can be repeated

Note: my inverter humms and the noise varies depending on the load e.g. switching oven on. Just did a test and that’s the case whether I‘m on or off grid. Although the humming is not as loud as when off grid. Not sure if it’s relevant

Given my serial number being HQ2220, is the PCBA retrofit merely for noise or could it cause of my issue?

What firmware are you running?

Do you have peak shaving on?
Is the system set up to loads on input and output?
What is your input current limit set to? Is it more or less than the expected total load?

MultiPlus-II 48/5000/70-50 v558
EasySolar-II HQ2220HAYVG v3.66
SmartSolar MPPT VE.Can 250/100 rev2 A115 v3.16

The house is on output and the PAC on in (parallel setup with an external CT)
The input current limit is 50A and my house is far from consuming that. The heatpump consumption is normally 3-5K so 15-25A

After rewiring so I can isolate the EasySolar from the grid and do some further tests it appears that

  • if PAC is on grid whilst EasySolar is cut off from grid (and as such house) switching on loads has no effect
  • if PAC and EasySolar are on grid, switching on loads causes alarm on the soft starter

So I suppose I have an electrical issue rather than electromagnetic one.
Now how to establish whether EasySolar or softstarter is at fault … ?
Has someone had a similar issue?
Could a galvanic isolator fix this issue?

How is the peak shaving set up?

No but a line reactor/choke might. (Scratch that its not a surge but a dip)

above minimum SOC only is ticked and no limit for import/export