RodA

This is a supply side issue. According to our grid code the supply should not exceed 253V. What happens here is your supply is already at the upper limit. Then once the inverter starts generating, it lifts the voltage over the limit. This most likely also indicates that your impedance to the grid is not low enough. The inverter should not be able to raise the voltage that much. This can be due to your supply, or installation. Sadly, a different inverter will not solve this issue*, as the problem is with your supply or installation, and any inverter that complies to NRS097 will disconnect and indicate a fault under these circumstances.
*unless you choose  a different grid code, in which case it is not NRS097 compliant anymore and should not be able to get a CoC.