I’m having an issue with my solar setup and could use some advice. I have a Fronius Primo 8.2-1 connected to the AC output of two Victron Quattro 48/10000 inverters in an grid-tied system with a battery bank. The problem is that the Fronius is pushing excess power back to the grid and overcharging my batteries, even when they’re at 100% capacity. This is causing the battery voltage to spike and trip the whole system requiring me to manualy start up again.
Here’s a quick rundown of my setup:
• Inverters: 2x Victron Quattro 48/10000
• PV Inverter: Fronius Primo 8.2-1, set to MG50 for microgrid operation
• Battery: 4x FreedomWon 10/8
• Monitoring: Cerbo GX with Modbus TCP for Fronius communication
The Fronius seems to be throttling too slowly or not responding properly to the frequency shifting from the Quattros, leading to overcharging. I’ve checked the firmware (Fronius is on fro34310.upd or higher, as recommended), and the Quattro settings align with Victron’s guidelines for AC-coupled systems (e.g., frequency start at 50.2 Hz). Despite this, when loads are low, excess PV power isn’t being curtailed effectively, and I’m seeing grid feed-in and battery overvoltage issues.
Has anyone experienced this with a similar Victron/Fronius setup? Could this be related to:
• A configuration issue with the PV Inverter Support Assistant?
• A delay in frequency shifting response (as some have noted it can be slow with large load changes)?
• Potential issues with parallel Quattros causing miscommunication or doubled power demand?
• A need for a Fronius Smart Meter to better control zero feed-in (though I understand it’s not typically used in off-grid Victron setups)?
ESS is usually used for on grid connections @Makhulu is off grid.
What other settings did you do on the fronius?
What normally happens is DC PV finishes charge on offgrid. Am going to assume you have DC PV as it is recommended as you need it for black start.
Have the inverters been programmed on the charger tab with the lithium profile according to the FW voltages 54.8v?
Is it a parallel set up? What is the current share like in the system? Are you DC cables all the same length?
That’s new to me, how can system know to use frequency shifting if there is no assistant with correct settings. I am not arguing your remark but just for my understanding.
The difference it that pv assistant disabled ac pv when a grid source is connected (usually a generator) and dc pv is used to finish the finer part of the charge cycle as it is easier to control.
Yes. There is a bit of confusing information there.
Says grid connected but is using the other PV assistant (for offgrid). And the screen shot shows no grid.
Maybe they meant AC coupled microgrid set up?
The battery voltage is at 63.8v which is crazy high for freedom won as well. (As they charge to 55.8v)
Some settings need to be reviewed definitely.
I have questions about component health in any case.
