TomSalmonZa

There are two aspects to this.
A normally open contactor/relay should be installed such that when eskom power dies (input to inverter), the contacts connect (output of inverter) earth and neutral. Now you have a local power plant earth/neutral bond which is a requirement. It MUST be temporary, because when eskom plant comes back online, then you must use their earth neutral bond (Always use the bond closest to the power plant (Power source) that you are using. You are not allowed to have two permanent earth neutral bonds in a system.
However, if eskom is available, and your battery is in island mode (Working off battery or solar) then the contactor/relay remains open because eskom is available, and you still have no earth-neutral bond. To fix this, ensure that your inverter is in "Hybrid mode", this keeps the AC Input active/connected even when using solar/battery and hence, the bond before your inverter is still in play.
I had an electrician sign off a C.O.C BEFORE this was done! No Bond and NO earth leakage, yet they signed off. Crazy
I forced them to come back and solve as per above.