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Hi all,


I'm designing a system with 2 inverters and one large battery, one of the inverters being a Fronius SYMO GEN24 10.0 Plus.

The battery is connected to the GEN24 inverter, and the 2nd inverter is only acting as an extra AC power generator (AC coupling) to the main AC bus.


One of the innovative features of the Fronius GEN24 is its ability to act both as a DC coupling (energy source is PV) and AC coupling (AC bus is source) simultaneously.

This is key to our design, as the second inverter will provide for extra power to be injected into the battery, adding to GEN24's own PV DC coupling.

For example if GEN24 PV is producing 4 kW and the other inverter is injecting 2 kW into the AC bus, the battery will get the 6 kW sum, minus the AC consumption of course.


We're using PV*SOL 2020 (R5) and the Fronius GEN24 is supported, in fact it is even supported in conjunction with the battery we are using, so we thought the simulation was fine.

Unfortunately upon running the simulation we got grid feed energy way too high for what we anticipated.

Upon checking the csv simulation results we were shocked to realize there is energy exported to the grid even with a low battery SoC and coupling capacity available!


PV*Sol is not doing battery AC coupling on the GEN24, all energy produced by the second inverter over the AC bus is being ignored the GEN24, so the production surplus over consumption is being fed to the grid instead of getting into the battery.

Can you please provide proper behavior for this inverter in your simulations by adding simultaneous DC and AC coupling?


Thanks in advance,


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Hi Joao,

that is correct, our simulation core doesn't support simultaneous DC and AC coupling modes. We have it on our list but we can't give a scheduled date for that feature, I am afraid.

In fact, there are a plenty of device topologies and most of all energy management algorithms implemented in battery systems available on the market that we are not able to reproduce in our simulation core. As you pointed out, the topology of a system, but also the management algorithms can heavily influence the energy flow through the system. We are aware of that and as I mentioned, we have that topic already on our list. But at least we hope that the user interface of the software and the help files are always clear about what we are calculating, so that there should be misunderstandings.

Kind regards,


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