question

Cracker F avatar image
Cracker F asked

Best way to reduce max PV Inverter Output (Factor 1.0 Rule)

Hey,
I'm searching for the best way to reduce the max. PV Inverter output to match rule 1.0 in case my AC is gone https://www.victronenergy.com/live/ac_coupling:start
I have 3 x Multiplus II 3000 and one 15kwp Fronius Inverter on the AC Out)

I don't want to put the PV Inverter on the AC IN, if I don't have to, because I'm no longer "Island ready".

Two options I think of (in case that my AC In is gone).

1. Run the system with more than 50hz so the PV Inverter never produces more than 9kw (Is this even possible to configure?)

2. Send the fronius inverter a max output value of 9kw (Don't know if this possible as well)

What do you think is the best way to do this? Is there a better way?

Thanks for help :)

Multiplus-IIAC PV Coupling
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3 Answers
marekp avatar image
marekp answered ·

@cracker0dks

You can disconnect string of PV panels from one Fronius's MPPT input when grid is gone.

The better solution would be to install Victron MPPT charger with 6kWp of your panels on DC side, and leave 9kWp connected to your Fronius on AC-out

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Cracker F avatar image
Cracker F answered ·

@MarekP Thanks for your ideas, also vaild options but would need to buy extra stuff and redo the strings and cables.

I found out, you can change the fronius pv inverter output power over tcp modbus with register: "WMaxLimPct" so the best option I found, is to set this value to ~60% in case that AC is gone. Should be pretty save I guess... would only be a problem if:
1. PV is running with max power (We have the max 70% grid feed in rule in germany so its not far of anyway)
2. Battery is full
3. AC is interrupted

So that is very unlikley and maybe not a problem at all ...

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

also vaild options but would need to buy extra stuff and redo the strings and cables.

But still cheaper than frying and replacing 3 MultiPlus.

In my opinion the only safe way is to physically disconnect some of the panels from the Fronius.

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