Growatt SPF 500SE trip Earth leakage on Utility side

[Vutshila]

I have installed Growatt SPF 500SE,  and is connected as follows 

1. AC input is taken from the Main CB before the Earth Leakage, connect via double pole CB to the inveter.

2. AC output from inveter to Essential Load is connected via Earth Leakage.

3. The DB Neutral is splitted into Essential and Non Essential load.

4. The Earth goes to the inveter and return to the DB. Meaning I have common Earth bar.

The earth leakage on the Utility side is tripping. Initially it was the sytem was working well.

On the none Essential load I have Geyser, Heat Pump, Oven and Washine Machine only.

The Growatt is connected to 4500W of Solar Pannels and 8.7kWh Lithium battery.

I have separate DC earthing connected to earth spike.

The Utility supply is a pre-paid meter.

 

Please advise on the test tobe done and recommended changes to the circuit 

I suspect that the inverter is bonding Earth and Neutral 

 

Regards