The comment about the ELU has nothing to do with the contactor/relay, if you do a permanent bond and fit an ELU on the input side of the inverter it...
Most burnt connections etc I have seen are bad workmanship , strands cut off before fitting into lugs , AC equipment used in place of DC , DC CB used...
If the neutral earth is that important, it should be done internally on all inverters and shut down the inverter automatically, with a built in fail...