question

Could be the 3.5mm jack problem...what type of inverter do you have?
https://community.victronenergy.com/questions/136511/total-overcompensation-with-the-multi-plus-2.html

The big variation of AC loads is actually happening?

Looks like a big load is turned on or off, in which case you can expect something like that.

I agree there is something up with the communication from the energy meter there.

What meter do you have how is it set up.

Thanks for replies, system is 3 weeks old

Inverter is MultiPlus-II 48/5000/70-48

Grid meter this the only info I can find remotely:

(Venus is v3.00 running on a Cerbo)

hard wire from Et112 ? yes as device list show USB ok

has it work ok up to this date ?

how do you have setup in ESS ?

I think I observe a very similar thing in my installation - see here https://community.victronenergy.com/questions/228017/multiplus-2-chargedischarge-oscillation.html

Could you solve the issue meanwhile?