Earth & Neutral must be earthed downstream DB of the inverter output at either the EL earth to Neutral or on the connection terminal strips of the earth and neutral a link can be done.The Growatt doesn’t have this done at board level and this needs to be done or you have a floating earth at the inverter which causes it to go faulty(Error 09).The Growatt SPF5000ES this can be done in Setting 24.