Why is my Fronius throttling power?

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james-davy asked Apr 30, '21

Why is my Fronius throttling power?

I have two fronius/victron 3 phase microgrid ac and dc coupled systems on two different properties that are next door to each other and are owned by the same company.

The one system is working well and seems to be covering loads and charging up the battery well. This system is smaller than the one next door that is not working well. Both Fronius systems are throttling power.

The problematic system is a 45kva 3 phase Victron/Fronius Microgrid - it is AC and DC coupled. The Fronius is on Output 1 and Output 2 is not in use.

3 x 15kva Victron
1 x Fronius Eco 27 with 28.18kwp PV
2 x 250/100 Victron MPPT's with 8.8kwp PV

1 x CCGX on version 2.66

2 x 32kwh Blue Nova batteries combined to make 64kwh - I have noticed that only half of this capacity is showing on the CCGX...could this be the problem?

The loads at this clinic can often reach around 20kw but often are around 15kw. We have ESS loaded and the MG50 selected for the Fronius. I have done all Fronius settings as per instructions in the manuals and are the same as the next door system. All Firmware has been updated.

The solar arrays on the Fronius all face north with no shading, the Victron MPPTs face West. I would estimate peak production on the fronius to be from about 10am for about 4 or 5 hours.

The problem is that the Fronius is not producing more than about 9.5kw at its most. I have checked and it says that it is throttled. I cant work out why. The batteries have not been to 100% for over a week and the weather over the last couple of days has been beautifully clear and the system should be producing more than enough power both for charging and handling the loads.

The grid has been intermittent and the voltages on each phase fluctuate quite regularly.

Please could somebody give some thought to this and let me know if I am missing something obvious? If necessary I can give access via the portal ID.

Thank you.

Fronius

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Answer 1 · 2021-04-30T09:15:33Z

james-davy answered · Apr 30, 2021 at 09:15 AM

Sorry, just to add to this:

The smaller system that is working well next door is 30kva 3 phase (3 x 10kva Victron) with a Fronius 12.5kva. Although the power on Fronius is being throttled it is understandable because the battery is on 100% and the loads are being covered by the solar. The Grid is not on but it does come on intermittently due to power outages and fluctuating voltages.

I have Grid on Input 1 on this smaller system and on Input 2 on the bigger (problematic system). I did try the bigger system without Grid and backed only by generator with the PV assistant but it was not working that efficiently. I hope to get it working well with ESS.

Thanks

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Answer 2 · 2021-04-30T09:17:50Z

james-davy answered · Apr 30, 2021 at 09:17 AM

Both systems have grid and also generator as a constant back-up and generator is turned on/off due to SOC conditions in the CCGX.

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Answer 3 · 2021-04-30T18:42:16Z

H.W.Oelofse answered · Apr 30, 2021 at 06:42 PM

Hello James, that is a bit of an issue. I presume that you will be running dvcc in the options in the ccgx? If so the fact that the registered capacity of battery in your system may be part of what is holding the system back there may be an issue with the communication cable or the bms for the one battery. If you could get the communication working for the second battery that may make a significant difference.

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james-davy commented · May 10, 2021 at 05:16 AM

Thanks for the response, I am working on this. I will let you know if this makes a significant difference.

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james-davy commented · May 10, 2021 at 12:11 PM

Sorry another comment on this is that the comms between the batteries is working well and they are are discharging and recharging equally. The comms are all fine. We are running DVCC in the CCGX. We will do a Firmware update on the battery and see if the CCGX will read accurately and see if that makes a difference. I don't think this is the main issue though.

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Answer 4 · 2021-05-10T20:27:32Z

thomasw-1 answered · May 10, 2021 at 08:27 PM

Hi James,

I would try Venus OS >=2.70.

Have a look to the thread "Throttled Fronius wastes up to 90% of capacity - improvement required on Zero-feed-in"

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james-davy commented · May 11, 2021 at 07:34 PM

Thanks, i will look into that

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james-davy commented · May 12, 2021 at 09:01 AM

I will try taking the Firmware back to the previous version -v 2.65 (the one that you found solved your issues in your post). Victron advise not testing the test versions on clients. These are not personal systems. Thanks very much. I will let you know how it goes.

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Answer 5 · 2021-05-14T13:44:47Z

james-davy answered · May 14, 2021 at 01:44 PM

Quick update.

Two fuses had gone!! Very simple overlook on my side and a great learning process. We put the strings of Fronius panels that were on the blown fuse lines into the unused / free string terminals of the Fronius (because we did not have spare fuses on us when we tested) and this improved performance by about 5kw but still was throttled. So we were about to try a new inverter but instead put in 2 new fuses into the two fuse holders where we previously had the strings as a last ditch attempt to see if it could make a difference - at this stage we had not put new fuses in to replace the blown ones. Once we did this it seems like the system is running so much better and I think it may be back to working properly again. If things change I will update.

Thanks for the input.

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