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Paul avatar image
Paul asked

3xMP2 with ESS, connecting 2x Fronius on AC-out or 1x MPPT250/100 and one Fronius?

Hi Victron professionals and entheusiasts,

My system consists of:
MP2 5000/48
Smartshunt
Smartsolar 250/100
Cerbo
8 kWh LiFePO4 battery controlled by a CANbus communicating Batrium BMS.
12 + 5 x 365Wp AEG glass/glass panels on a SMA STP5.0
10x 365Wp AEG glass/glass panels, each connected at a Enphase IQ7+ on one phase.

Yesterday, I removed 10 pcs Enphase IQ7+ micro inverters from our roof and connected the panels over two separated strings of each 5 pcs 365Wp panels in parallel tot he Smartsolar 250/100.

With the ESS running I have 3 options now:

a) Connect all panels to the two Fronius Symo 4.0 inverters connected to the inverting AC-out of the MP2 for backup during grid failure OR

b) just add one Fronius at the AC-out and charge the batteries with the 2x5 panels connected at the Smartsollar MPPT 250/100?

c) keep the excisting SMA on grid side and use the Fronius to power my house when grid fails and accepting that the SMA will shut off during failure.

What would bet he best option?

Appreciate your opinion!


MPPT SmartSolarFronius
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2 Answers
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solarmax-canarias answered ·

2 X Fronius 4.0 will overload the charger (1:1 rule). The mix of AC- and DC coupling works damn great, so I can recommend it! Is the SMA three phase? Not sure if STP sunny tripower means, If not you could use that one on AC-out and the MPPT separately

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Paul avatar image
Paul answered ·

Apologies for me being not clear: 2 x 4.0 Fronius wil be 2x 3 phase so 8kW 3 phase where 3x MP2 5000/48 is 15kW. Enough reserve...

Happy to hear! because I now can:

- Connect 2x5 panels of the garden house in series to one string of the SMA STP5.0 and the 5 on the backside of the main roof to the other MPPT input and

- connect the 12 panels on the front roof in a 4s3p configuration parallel to the Smartsolar 250/100. I cabled every panel to inside of our house so I am free to make any configuration that suits my needs.

When in far far future a Fronius Symo 4.0 is available, I will swap the SMA STP for a Symo 4.0

Victron: Lego for Nerds :-)

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