Can parallel inverters be brought on line as load increases? Saving power on low load but giving the capability of a high output if required
Nope. Its a manual configuration. Parallel inverters are one system.
Have a read of the parallel and 3 phase config guide and training video.
The low load power of 2 inverters in parallel is always higher than or equal to the no load power of an equivalent single inverter.
However, operating 2 inverters in parallel does give you the possibility (with reconfiguration) of operating at reduced power in the event of a single unit failure.
The low load power is generally insignificant compared with the typical household overnight load (i.e. Fridge + Freezer cycling + some other back ground loads).
For boats and RV’s this is not always the case.