The function of the inverter (as I already said) is to transform the low voltage current of the batteries into 230V alternating current (hence its name: it "waves" the current)
It draws its power from the batteries, which if the guy who did the installation has done his job, normally have the capacity to provide the power requested by the inverter at its maximum load (or that being presumed to be maximum)
If the batteries cannot do this, it is normally that they are discharged, so the installation must be stopped.
So what would be the purpose of an MPPT in an inverter? find out how much power it can draw on the batteries?
Let's admit ... then how should he react?
I have my house to supply, several devices are on the way, the (so-called) MPPT of my inverter determines that the batteries are not able to provide everything I ask ... so he will try to reduce the power out ... but how?
So what is your MPPT inverter doing? it reduces the output voltage, it reduces the frequency?