When using the inverter as a UPS in Islanding Mode it is important to ensure the UPS output is maintained as a class one connection rather than a class two.
If the output is a class two then all you can connect to it is a single socket, if you want the output to be connected to the household essential loads then you would need to change the classification of the output from the class 2 to a class 1
Items like toasters refrigerators light fittings are mainly class one products if you don't create this bond then you carry a small risk of electrocution.
This is very important