I am designing a Victron ESS with MultiPlus/Quattro, BYD battery and an SMA Sunny Boy 3.0 PV inverter (AC-coupled).
The system goal is seamless backup operation with minimal PV interruption during grid loss.
Question:
- What is Victron’s recommended architecture for AC-coupled PV in ESS (AC-in vs AC-out behavior during islanding)?
- What is the expected behavior of SMA during grid loss and island formation by Victron?
- Is frequency shifting intended as a primary PV control method in this configuration, or only secondary curtailment?
I am trying to avoid PV restart delay during transfer to island mode.
Hi,
there is a guide about AC-Coupling, dos and don’ts here:
That’ll be a good start before starting to design 
Thx for your quick response. I interpret it is possible on both ways, on ac-out it is more off-grid configured and on ac-in some less can have temporary mppt outage. Does the multiplus disconnect the mppt (connected to ac-in) after grid outage (will it power of the mppt) or create minimum power to contue mppt flow.
To start with easy & stable setup without to much specific configurations, I tend to ac-in in first place. Agree?
Ac in will be completly disconnected during grid loss.
Only pv on AC Out will run.
Mppts (as in “MPPT” as the productname of victron solarchargers) will be connected to the dc bus directly and charge the battery more efficient, since it avoids double dc-ac conversion.
If you don’t have purchased something already, I would recommend only using dcpv if offgrid is a important usecase. Way less constraints and easier to manage.
Thx. Understand from your reply that a dc pv would give an easier and more stable setup. Due to cuurently having an AC pv, will start with that, connecting to ac-out and configure the sma in island nodus.