When using a generator with a built-in RCD it must be connected to the Grid terminals of the inverter, not the Gen/Aux terminals to avoid nuisance tripping as outlined in our article below.
When setting up an off-grid system like this there are some important steps to take in order to make the system work correctly. Essentially it will be set up to emulate an on-grid system using the generator in place of the grid.
An on-grid system typically has an earth-neutral bond within the local transformer outside of the property meaning that as long as the property is connected to the grid there is no requirement for any additional E-N bonds. However, when properties are designed to operate in Signal Island Mode they are set up with a temporary earth-neutral bond (usually within a distribution board connected to the inverter Load terminals), which uses a relay to connect to this temporary E-N bond when the grid is lost. More information can be found in the article below
The way to approach an off-grid property with an RCD protected generator is very similar, just with the generator acting in place of the grid. Because there is no grid E-N bond needs to be created at the generator itself which should also be earthed using a local earth rod. It is common for generators to have a built in E-N bond so please check with the generator manufacturer or documentation to see if it has one built in or if it needs to be created externally.
On the generator side, create (or use built in) E-N bond and a local earth rod
On the load side, create an E-N bond in the distribution board connected to the load terminals using an NC or NO relay as per the above article.
Common both earth rods to each other so they share a reference to earth.
When the 'grid' (in this case the generator on the grid terminals) is active it will use the E-N bond at the generator and keep the load side one isolated. When the grid is lost, the relay will close/open to connect to the temporary E-N bond in the load side DB. When the 'grid' returns and the grid relay closes this will disconnect the relay to the temporary E-N bond, ensuring that only one of them is in use any any time.
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