Black start means that a completely shut down system (due to empty batteries, switched off BMS) can start again independently without the system being started from the outside (grid).
This is actually done using a DC-coupled MPPT or mains charger on the generator, which charges the battery. When the battery has enough voltage for the BMS to release it again, the MultiPlus/Quattro can start and build up its grid at AC-Out. PV inverters can then provide additional power andcharge the battery or supply loads. Anything connected to AC-In (PV inverter, loads) will not work. It is important here that all required components (e.g. GX-Device if required for control) are supplied via DC and are not connected to a power supply unit on AC-Out, for example.
