Hi, i want to couple my Fronius Symo 10 kW inverter on the AC out. I will get 3xMuliplus2 6k5 and 16kWh LiFePo4 Battery. This violates the victron rule in the title. As far is i understood this is to prevent battery overload when the net disconnects with a fully working inverter. So i want to w…

The factor 1 rule is that the PV inverter rating must not exceed the inverter rating. The victron is 6000KVA, 5000W. The fronius must not be capable of exceeding this. The rule exists not just for grid failure but also for the conditions when loads switch at near full charge. AC2 is also restrict…

[image] Nick: The factor 1 rule is that the PV inverter rating must not exceed the inverter rating. The victron is 6000KVA, 5000W. The fronius must not be capable of exceeding this Unless I’m misunderstanding something: the Fronius Symo 10.3 (I suppose that’s the one?) does 10kW in total, wi…

As long as it can’t shunt more that 5000W into the inverter on a single phase and the batteries can deal with that then it would comply. Your battery would be facing the full brunt of the PV inverter so must not be undersized.

@TigerQuasare So you are correct i totally forgot the symo is three phase. so why is there a need for reprogramming @Mad_One ; frequency shifting would take care of battery overcharge when the grid is disconnected. If it is set up correctly. AC-coupled PV with Fronius PV Inverters [Victr…

I am sorry for being unclear: The factor 1 rule is obeyed. I’m talking about the min battery capacity in 3.2. AC-coupling and the Factor 1.0 rule [Victron Energy] I will obey the rule if necessary, but finding a way to get around this would be preferred. I…

[image] Markus: Battery is full, Inverter runs at max, grid fails: Frequency shifting / Inverter adapting is to slow => stress for the multi &battery. Once the grid fails, at least for me the Symo instantly drops to zero, then slowly syncs back to the MP2 offgrid and ramps up production again…

Hi @Mad_One I recommend adding at least one battery. Why? With 16kWh your battery will be charged before lunch time. You will waste majority of your energy when selling at negative day ahead price. When charging a single 300Ah battery with 150A, your balancer will not keep the cells equalized. I…

During offgrid operation the MP2 controlles AC-PV via frequency shifting. Current PV-inverter shall implement this feature to get grid certified. Starting at 50,2Hz they shall start reducing generation at 40%/Hz. Above 51,2Hz they shall drop to zero. MP2 starts with save 53Hz and adjusts the freq…

Well i am on a small budget right now. I am planning to increase the battery and also the solar. But for now i have limited resources. More than one of these banks is not in the budget right now. I get 0.07€ Einspeisevergütung for each kWh i send to the grid. The 16kWh battery will not be empty on …

@Mad_One I had to take same decision. Pls mind all MP2 in a cluster need to have same hardware revision. You can read about my experience at: [image] Germany / 3p MP2 5k / 8.5 kWp / 56kWh / Hoymiles Show us your system Hello Victron communty! I like to descr…

Evade 4.8kWh battery per 1.5kW Peak for Inverter on AC-Out

DIY

BjoernK (Björn Kellermann) 10 May 2026 20:51 13

@Mad_One

I had to take same decision. Pls mind all MP2 in a cluster need to have same hardware revision.

You can read about my experience at:

If you like, we can talk. Pls write to bk-ve@gmx.de

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Evade 4.8kWh battery per 1.5kW Peak for Inverter on AC-Out

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