AC-IN and AC-OUT connected to the same distribution board in a three-phase ESS system

DIY
, , ,
1

Hello,

With an ESS configuration, I connect the AC Out 1 of my three MultiPlus units (configured in three-phase) to the main terminal block of my house distribution board.
The grid connection also arrives at this same terminal block, but upstream there is an ET340 meter.

From this terminal block, the house loads are supplied either by the MultiPlus units and/or the grid, through the protections in the distribution board, including the circuit breakers that feed the AC-IN of the MultiPlus units.

Is this type of connection possible?
is it acceptable to connect AC-OUT1 to the main distribution board while AC-IN is also fed from the same busbars? I would like to confirm that this configuration is safe and understand how the system detects a grid outage without creating a loop from AC-OUT to AC-IN.

It seems that in ESS systems it may be possible to have this double connection to the main switchboard (grid and AC-Out1), so the grid can complement if the multiplus has not sufficient power or batteries energy to supply.

Thank you.

2

You can’t connect AC_In and AC_Out together, this is forbidden!

Either you connect all house loads to the AC_Out and grid only to AC_In, or you use a special switch for the backup power supply that completely separate the grid from the emergency supply like a Kraus & Naimer KA63B or others.

But please do not connect them together, and if already did, then separate this immediately.