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Josep morancho avatar image
Josep morancho asked

Fronius in AC-out2 & Relay

have an off-grid system with Multiplus II 5000, 2 x Pylontech US5000 and smartsolar 250/70 with 3kw PV array.

I want to upgrade my system with a Fronius PV inverter to power my new cooling system during the day.

Can the Fronius PV Inverter be connected to the AC-Out2 line?

If yes, Can the AC-Out2 relay be configured to open when the battery SOC reach some low value and close again when the battery SOC reach a value higher than the disconnection value? This is to avoid that high cooling load discharge the battery in cloudy or raining days or when there is not enoigh PV inverter power

On the other hand, Does the power of the Fronius PV inverter injected in AC-Out2 line flow to AC-Out1automatically or the power injected in AC-Out2 does not flow to AC-Out1?

Thanks




FroniusRelay
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2 Answers
Sebastian avatar image
Sebastian answered ·

The Fronius on AC-Out1 would be the best option in my opinion.
If you would disable the Fronius on Out2, when the SOC is to low, the MPPT must rise the SOC on its own while the Fronius could helfed to deliver some power. So less energy in low SOC situations.

The cooling load can be switched based on the SOC on Out2 without loosing energyproduction with the Fronius on Out1

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Alexandra avatar image
Alexandra answered ·

@Josep morancho

The pv on ac2 will contribute to the whole system loads and charging.

Why not have the pv inverter on ac 1 let the system control it and have the larger load on ac2 and control is with battery soc?

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Josep morancho avatar image Josep morancho commented ·

Is another option of course!. My initial thought, not completely developed yet, was:

1 - I want to preserv/isolate as much a possible my critical loads from not critical.

2 - my crtical loads are very well covered with actual system. MII+SmartSolar+Pylontech is very robust and overdimensioned to protect as much as possible the critical loads

3- PV inverter is not requiered at all for critical loads. Moving PV inverter in L2, will be essier to isolate from actual system that it is running perfectly for a couple of years. Cero problems.

4 - if non-critical loads turn-off or are not required, MII will have to deal in L1 with a high power coming from PV Inverter. Of course also if it is in L2 but i can isolate easily.

As I said at the begining, this is my initial thoughts but of course i did not think in your option.

Has some advantatges and dissatvantatges.

The advantatge would be that if the battery goes low in SOC and L2 is disconnected, if PV inverter is in L1 will help SmartSolar to charge battery faster.

Any other advantage or disadvantage?

I am in the initial design and discovery phase

Another option would be a second smartsolar with a second PV array.

Thanks

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