Barry Clark avatar image
Barry Clark asked

Generators compatible with Fronius grid tied inverters.

We have a Fronius grid tied inverter connected to the output of a Quattro. Fronius grid tied inverters have a shutdown facility which utilises frequency shifting the ac by 1 Hz.

Suppose we have an ESS with a Fronius, Quattro and a generator. If the generator kicks in and the frequency is not exactly 50 Hz, the Quattro will frequency-track it and in doing so inadvertently shut off the Fronius grid-tied inverter.

Do we have to purchase a super-stable generator with exact 50 Hz frequency in order to prevent conflicts between the frequency of the generator and the grid-tied inverter?

MultiPlus Quattro Inverter ChargerGeneratorFroniusfrequency
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3 Answers
ponzoa avatar image
ponzoa answered ·

I take it you've configured the grid code MG50 in the AC Coupled Fronius inverter. This way, it will continue to produce upto 53Hz approx (53,2Hz I believe the cut of is set to), above which, the Fronius will stop producing. This is correct behaviour. Try to lower the frecuency of the genset which sometimes can be done by lowering the RPM.

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ccc-telecom avatar image
ccc-telecom answered ·

Good Question, OR rather "How can I continue to use the AC Coupled Fronius Primo/Symo to generate solar power when the selected Quattro input is a generator, or do I have to accept that it switches off which seems to fly in the face of the Fronius microgrid strategy and documentation about being able to use a fronius OFF-GRID with a generator

>>> Without a solution I will have to remove solar panels from the Fronius and put them on a Victron MPPT which means more Victron MPPT or bigger generators in every configuration <<<

This applies to both the ESS Assistant (Main Utility Power Connected) and the PV Inverter Assistant (no Utility Power - Off Grid), when the generator is started during the day the fronius switches off, system is configured for zero feed in and battery is in a low state of charge

The generator is required to charge the batteries, hence the loss of Fronius power is a problem, hence how do you set the Victron (float voltage / frequency shifting parameters) and Fronius to prevent the rejection of the Generator as an input source for the fronius . . .

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tobyfw avatar image
tobyfw answered ·

I had exactly the same issue today. Not sure, though, if this issue needs to be tackled on the Quattro, or on the Fronius, on on the generator. In the end, the off-frequency (in my case, over-frequency) is there, it is not the Quattro's fault.

So I guess either
a) the Fronius should be set not to throttle (not an option, dangerous when Quattro is overloaded!?)
b) frequency would need to be actively balanced, not sure if the Quattro can do this at all, probably additional hardware needed
c) I could adjust the RPM of the generator with the calibration screw (in my case, slightly down from 52 Hz)

d) get a more expensive generator (no plans)

PowerAssist = Off, WeakAC = On, Accept wide input frequency range = On, UPS function = Off, AC input 1 = Generator, Grid code "other", no LOM detection (earlier we had issues with the generator being not recognized or shutting off on high loads - those settings solved the issues)

We are expecting power outages over the next months, wasting solar would unnecessarily increase the amount of fuel required by the generator. Thank you for ideas on how to improve the situation!


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