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freek avatar image
freek asked

15 kw Quatro Inverters 3x in parallel on a 3 phase system.

I bought 9 x 15 kw Quatro Inverters connected to a 100 KVA battery.

3 x 17 kw Fronius Symo Grid Inverters connected to 112 panels of 550 w each.

On the PV side I have a total of 90 panels or 550 w each connected to 6 x SMARTSOLAR MPPT RS 450/100 450/20.

In South African terms a R3.5-million-rand investment.

This system has caused me nothing but frustrations. It cannot handle our max load 70 kw during loadshedding’s. It is about 25 kw per phase.

This system stops with in error of Voltage overload. At least once a day. My installer replaced one Quatro, one Fronius, one Smart solar MPPT. Redo the wiring on the AC side. With no deference in result.

I start losing trust in the fact that Victron is not capable to handle large Loads.

My installer is not giving me an answer or solution for my problem.

Victron needs to come with a solution as I am starting to lose trust in this brand?

installation
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Juha Tuomala avatar image Juha Tuomala commented ·
Could you share pictures of your installation? It would be interesting to see as it’s near impossible to get access to such site.
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5 Answers
nickdb avatar image
nickdb answered ·

That is a large and complex system. Installed and designed properly they work.

You haven't stated what your specific battery setup is, model, numbers etc - 100kWh battery on 135kVA of inverter is not an ideal ratio, but it depends on what the discharge specs are.

Regardless, you need support not a community forum and it sounds like your installer is out of their depth.

I would encourage you, as per our guidelines, to log a request at victronenergy.com/support

You will not get the answers you need from a community forum and that is the best route to get somewhere. Support is owned by the distributor the installer purchased from and the link above, should route it to them, and give Victron some oversight.


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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @freek

I've taken a short look at your system and found that on L2 there is an imbalance between inverters.

Please ask your installer to thoroughly test current distribution between parallel inverters (basic testing to be done at every big system), it looks like one (?) inverter is somehow disconnected at the output (open fuse? wiring?). This causes that phase to be able to handle less power, hence the overloads.

When an overload happens, if the PV production does not stop quickly enough, you get the 'overvoltage on output' error that you see.

How to spot this: look at the output Current per phase, you'll see that it's much more on L2.

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nickdb avatar image
nickdb answered ·

@freek I have also taken the liberty of editing your username so you don't publish your private email address to the whole world, I am sure you'd rather not be spammed. The validation email was resent, just in case.

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Michelle Konzack avatar image
Michelle Konzack answered ·

You have a MINI battery of 100kWh and connected nine 15kVA Quattros to it or 135kVA.


Your batteries are hopeless to small for it.

I have installed last year two similar systems, and one has 48V/8700Ah (417kWh) and the second 48V/13050Ah (626kWh).


The biggest problem you face is probably if your 100kWh batteries are full and the Quattros go into frequency shifting and switch off the three Fronius GTIs, hence if you give a load of 70kW on it, the Quattros have to get the Energy out of the batteries (which break down under this load) until the Fronius can jump in.


How did you cable the Batteries and Quattros?

Maybe also your cabled are too long and too thin.


I had to use for the Quattros to the PowerRail (4m) 2x 95mm2 for PLUS and MINUS, and since you can not get such cables into the Quattros, I used a reductor cable of 2x70mm2 each.


The cables are all H01N2-D high performance Welding Cables.

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freek avatar image
freek answered ·

Thanks for the input.

The total of 9 Quatro’s 3 in parallel per phase.

For low heat generation you need to space them to the suggested specification therefore connecting to the busbar was a challenge. Making sure that the length of the cable is all the same length to get correct balance resulted in a lot of cable.

The cables we used was 2 x 95mm^2 per positive and per negative per Quatro. That is 4 cables of 95mm^2 into each Quatro.

The Battery 100 KVA might not be to the spec of the 9 Quatro’s (135KVA).

The battery is a C1 rated battery.

The more I read about this the more I believe your advice might be our solution.

The solution might be to add another similar battery in parallel to make it a total of 200KVA. To match the inverters total of 135KVA.

It will however be a very costly experience with no guarantee.

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nickdb avatar image nickdb ♦♦ commented ·
First follow Daniel's advice and resolve the imbalance on L2. Something is broken there..
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freek avatar image freek nickdb ♦♦ commented ·

I was wondering about the imbalance on phase 2.

It is always the phase 2 master Quatro to show the overload volt alarm. I assume it is not the imbalance between phases.

Therefore, the imbalance between the 3 parallel connected Quatro's might be the problem. If Daniel took a short look at my system. why did my installer not pick it up. Is it that easy to see the problem?

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nickdb avatar image nickdb ♦♦ freek commented ·

The diagnostic tools available remotely, have shown you have one inverter not contributing, or hopelessly imbalanced.

Yes, it is a basic test that should be performed with a clamp meter on every new install to verify everything is a) working and b) evenly balanced across master and slaves.

Your L2 inverters aren't balanced, for whatever reason, and that is as basic an onsite check, as there is. A lay person, with a R2500 meter, could check this themselves..

The VRM data available, and logged alarms on your site, should also not be rocket science to anyone qualified and experienced to build these types of systems.

A parallel set is logically one inverter, so only the master will moan.



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freek avatar image freek nickdb ♦♦ commented ·
We manage to find one of the Quatro's on phase two not contributing to the load at all. The reseller is going to replace this unit. Hopefully It will solve my issues with this system.
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