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Luis Fernandes avatar image
Luis Fernandes asked

60kW Off Grid system with Quattro and Fronius +85 kW Storage

Hi Everyone,

I'm currently planning to build a off-grid solar system to be used in an agriculture farm. The system will be mostly used to power the water irrigation system and to will have to provide a mini-grid as we are several Kms away from the grid.

The system will be composed of the following components:

1-60kW Solar array with 450W mono panels

2-3x Fronius Eco 27 3 Phase Inverters

3-4x Quatro 15000VA (2xPh1, 1xPh2, 1xPh3)

4-85kW Battery Storage


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The main load of the system are the water pumps that source water from a borehole well and the distribution pumps that adds boost pressure. The majority of load will be exclusively operated during sunlit hours and the energy produced should be consumed directly from the output of the Fronius inverters while the remaining output will be used to slowly charge the batteries. The are a few small loads such as lights, a weather station and an alarm system that will be using the battery during the night as well as the residual consumption of the Quattros and Inverters.

When the main loads are not active the frequency shifter functionality should adapt the inverters output.

The reason for the post is to ask for comments on the setup, if anyone thinks there something I missed or any foreseen problems. Also I would like simplify the setup and use a single 3 Phase inverter, does Victron provide a compatibility matrix of brands and models that enable off-grid functionality with the Quattro.

Thanks a lot

MultiPlus Quattro Inverter Chargeroffgrid3 phase
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2 Answers
basil katakuzinos avatar image
basil katakuzinos answered ·

Look, i could be very wrong but i am yet to see an installation with a different amount of quattros on one phase. It is normally balanced (1 quattro on each phase or 2 quattro on each phase etc...).

I will list a few things to keep in mind when designing your system.

1) DC system needs to be identical to each quattro, make sure wiring is not longer or shorter to any inverter.

2) Your system only has AC Coupled solar (through the Fronius inverters) this means if your batteries die, you will need to connect a generator to start up the system again (As an AC Coupled system can not black start) . Maybe consider adding some DC solar using a Victron MPPT and a panel or two just to start up the system if it ever goes down or flat.

3) Make sure you follow the Factor 1 rule, Your AC Coupled solar (Fronius) can not exceed the max VA rating of your Victron inverters (This is not a problem with your current configuration but will be if you only have 3 Quattros and not 4).

Could you provide us with a list of all your loads and what their power requirements are so we can help size your system out?

Maybe give these a read

AC-coupled PV with Fronius PV Inverters [Victron Energy]

AC-coupling and the Factor 1.0 rule [Victron Energy]

Parallel, split- and three phase VE.Bus systems [Victron Energy]


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basil katakuzinos avatar image basil katakuzinos commented ·
Compatible Fronius inverters are listed in first link I attached.
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Luis Fernandes avatar image Luis Fernandes basil katakuzinos commented ·

Hi There,


Thanks for taking the time to reply, yes I'm aware of the Factor 1 rule hence the 4x quattro, as for the asymmetric number per phase, the question as been asked directly to Victron that confirm as long as they are the same models there is not a problem.

The scenario you described where the batteries completely run down, I did not consider but I was thinking to add a small backup generator for emergencies so thanks for the advice I think that will be essential now. Regarding the distance of the distribution and other pumps location we deliberately placed all the equipment in order not to exceed 200m from the furthest equipment.

In regards to size I have already done a detailed analysis and expect not to have a peak load of no more than 30kW and according to the estimates from this calculator:

https://ec.europa.eu/jrc/en/pvgis

we will be able to produce between 28 kW/h to 44kW/h during the summer months that are when we will have the system in use.

What I was interested as well was to explore other brands other than Fronius so that I could find a model that would allow me to replace the 3 inverters for a single one.

Thanks again.

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basil katakuzinos avatar image
basil katakuzinos answered ·

Another concern is that you mentioned distribution pumps, how far away are they from where you want to install the system. It is quite hard to run power for long distances +-500 meters without moving into the territory of transformers and HV distribution which are beyond the scope of my knowledge.

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