Fronius Solar inverter review

Fronius Symo image

Fronius Solar Inverter Review Australia - Updated April 2022

Fronius are the 12th largest solar inverter manufacturer in the World.

All Fronius inverters are designed and made in Europe (Austria).

Fronius inverters have a proven record for reliability.

The Primo (single phase) and Symo (three phase) 'snap' inverters have been with us since 2013, and it's a testimony to how good these products have been that they remain the top selling inverters in Australia a remarkable 8 years later. "If it ain't broke, why fix it?"
These 'old faithful' Fronius models aren't 'hybrids' so not battery capable.

However, Fronius DO have some new products released 2021, and they ARE hybrids.
The original Primo and Symo will carry on, no doubt for several more years, but the new Fronius range of single and three phase GEN24Plus is mostly what this review is about.

Fronius have retained the Primo and Symo names so the new inverters are the Primo GEN24Plus and the Symo GEN24Plus.

The Primo GEN24Plus
They are single phase inverters that are hybrids that can connect to battery storage.

There are various models from 3kW to 6kW, but in Perth, 5kW will be the top seller by far.
It is currently only compatible with BYD high voltage HVM and HVS batteries.

The BYD HVS battery options for the Fronius Primo GEN24 are 5.5kWh and 7.7kWh of storage.
It is then possible to parallel another 5.5kWh/7.7kWh battery stack, and if need be, another again, but each new stack needs a new BMS and it is a VERY expensive way of doing things.

The BYD HVM battery with the Fronius starts at 11kWh and goes up to a much more respectable 19.3kWh of storage, and again, parallel battery stacks are available to increase storage

It's a shame to me that they can't start compatibility with the HVM battery at a lower level, like 5.5kWh or increase compatibility with the HVS to its limit of 10.2kWh, but apparently, they just can't.

Here is a link to the Fronius battery compatibility chart.

The 5kW model sells for $3,355 which is $1,175 more than the regular 'Primo 5kW' and almost double the price of its most serious 'hybrid' competitor, Huawei.
But that's the price of European-made and an unrivalled reputation.
There's a bunch of brands, 11 to be exact, that sell more inverters a year than Fronius, but big volume and top quantity rarely share the same bed.

The Symo GEN24Plus
There are two versions of this 3 phase hybrid inverter, so it is important to understand the difference.
The 3kW to 5kW models are different to the 6kW to 10kW version.
I very much doubt we will ever sell anything other than the 5kW model in the smaller range, so I'll focus on that first.
This is a 'cut-down' version of the larger 6-10kW models and is therefore quite a bit cheaper BUT it lacks one feature.
It does not support battery back-up in a grid outage.
Further down I explain PV Point and Back-up, and this 5kW three phase model does have PV Point, but will never have back-up.
If you want back-up then you must go for the 6kW to 10kW range.

The 6kW Fronius Symo is $4,200 and the 5kW $3,850.

I was initially surprised that there was so small a price gap between the 5kW and the 6kW considering the 5kW doesn't support 'full backup' until I learned that in reality, the Fronius 6kW doesn't really include anything for 'full backup' either as you need to spend another $2,000 on components as described below.

The 6-10kW models deliver backup up of 3kW of power per phase with a 4.5kW per phase initial surge tolerance.

I'll explain the back-up features starting with PV Point.
PV Point is an RCD protected GPO (power outlet) that only works when the grid goes down.
You don't need a battery plugged into the Fronius, it can work directly from the panels.
Approximately 60 seconds after the grid fails, the inverter will re-direct up to 3kW of panel power to this outlet, so obviously, this only works during the day.
As long as whatever you plug into this outlet draws less power than the panels are producing, it will keep working, but if the load exceeds the panel output, it will trip, shut down the inverter and then the inverter will try and start up again a little while later.

The fact that a few passing clouds might end up reducing the panel output so the inverter shuts down renders this feature more into the gimmick category than anything truly useful, but it's a different story if a battery is connected.

If the battery is connected, then the PV Point can draw power from both the panels and the battery which will stabilise supply.

The second form of 'back-up' is what Fronius call 'Full Back-up'
This means that the inverter can pull power from the battery during a grid outage.
If the sun is shining at the time, then the battery can be topped up by the solar panels.
Despite the name 'full backup', if you have a 5kW inverter then the maximum continuous backup power is 5kW.

If you read the Fronius marketing material, watch the videos etc, you would be forgiven for thinking that Fronius have included 'Full-Backup' in the inverter and that all was needed was a connection to your circuits in your switchboard.

For example rival brands Goodwe and Sungrow state they have full backup included and they really mean it.
All the required contactors, breakers, relays for backup etc are built into the Goodwe and Sungrow hybrid inverters so all we do is run a second AC cable from the inverter to the switchboard and connect it to the required essential load circuits.

Not so with Fronius. An additonal, non Fronius-made external box is required to achieve backup.
Ready-made boxes, which include the Fronius single or three phase smart meter, are available at $1,200 for single phase and $1,750 for three phase from national wholesaler BayWa RE.
Some electricians may take the time to make up their own backup box themselves to save some dollars.

I should point out that Fronius are by no means alone in requiring an extra box of contactors, breakers, relays for backup.
Sungrow and Goodwe are the exception, not the rule.
Huawei, SolarEdge, Growatt, Tesla Powerwall etc...all need an extra quite expensive box, for backup.

Anyway, the way it works, once installed, is simple enough.
The grid goes down and the inverter sends a signal to the relay in the back-up box to cut the supply of solar/battery power to the house and grid; an important safety function called 'Anti-Islanding'.

About 60 seconds later, power from the battery, topped up by the solar panels (if it's daytime), will then be directed down the additional single or three phase cable running from this backup box to the various circuits in the switchboard that have been designed to receive power during grid outages, often called 'Critical loads'.

Despite the name 'Full Backup' it's really not. You can't run everything in your house from it, but with some common sense discussions with the installers you can cover what's important to keep alive during an outage.

Here are some common questions and answers about Fronius solar inverters.

Are Fronius inverters battery ready?
The single phase Primo and the 3 phase Symo are NOT battery ready, but the latest GEN24Plus models are ready to connect BYD high voltage solar batteries and later, LG Chem batteries.

Are Fronius inverters noisy?
The existing Primo and Symo inverters are noisy, 65Db when the fans are working hard, but the new GEN24Plus models are much quieter at 44Db. Despite the very obvious fans visible in the front of the new GEN24Plus models, the better cooling and lower noise of the new generation models is due to better internal design and a far superior heat sink than the old models.
Our observation has been that the GEN24Plus fans rarely even operate, which rather proves the point that other inverter manufacturers have been making that passive cooling is very effective with a good design and heat sink.
It seems the fans on the GEN24Plus are really there for show.

Is Fronius WiFi reporting good?
The free version isn't all that great, but the paid 'Premium' version ($39 a year) gives most people what they want, and if it's not enough, there are APIs to export your solar data into other applications, although, again, there are limits to how much you can pull down for free before you start getting charged.

Can you oversize the new Fronius battery inverters with even more panels?
Yes, Fronius allow 150% oversizing, so the 5kW inverter can have 7.5kW of panels when a battery is connected.
I have asked Fronius as to why this oversize limit is so low, as Huawei Growatt, Sungrow and SolarEdge can oversize to 10kW of panels on a 5kW inverter with battery (200% oversize), but Fronius say they are sticking with 150% max.

Is the battery connection to the GEN24Plus DC coupled?
Yes it is. It's a true hybrid inverter capable of handling both panels and battery.
Western Power seem much happier with approving DC coupled batteries over AC coupled, especially when additional over-sizing of panels has been applied for.

Can the GEN24Plus inverters be AC coupled?
Yes. If you have an existing solar inverter, perhaps another Fronius, you can leave it in place to run the solar panels and then connect a GEN24Plus, single or three phase, to your switchboard with a battery plugged into it.

Unfortunately the two inverters, even if both are Fronius, can't talk to each other, and you can only have one consumption meter (which would go on the GEN24Plus), but the AC power from the solar inverter will first power the house, and then flow to the second inverter to charge the battery.

What is Fronius Multi Flow Technology?
It's marketing spin for a feature that ALL hybrid inverters have.
It simply means that the inverter can supply power to loads in the house and at the same time pull down extra DC power from the panels to charge the battery.

Let's use Huawei as an example, because, as described above in the 'Oversizing' section, they allow, for example almost 10kW of panels to be connected to a 5kW inverter with a Huawei battery. (You get paid STCs for those extra panels too).

So, it's 10am, the sun is shining brightly, the battery needs a good recharge after discharging overnight.
At the same time, the hot tub, oven, kettle etc are pulling a lot of power in the house.

In this instance the 5kW inverter pulls 5kW from the panels to supply 5kW of AC loads in the house and at the same time, pulls ANOTHER 5kW of power from the panels to store in the battery.

That's 'multi-flow technology' whether it's a Fronius, Huawei, Gooodwe, Sungrow etc etc, hybrid inverter with a battery DC coupled to it.

You could also add to that decription that any hybrid inverter can deliver power from both the battery and solar panels to the house, or draw power from the grid and solar panels at the same time to the house to charge the battery.

Electricity can be directed to flow wherever it is needed depending on how the inverter has been programmed.

What is Fronius SuperFlex Design?
It means you can have three strings of panels, two of them in parallel.
Let's say you wanted to install 18 x 370W panels (6.66kW)
You could have a string of 6 facing East for the morning sun, a second string of 6 facing North, and a third string of 6 facing West for the afternoon sun.
Two of those strings would be connected together, say West and East, on one of the inverter MPPTs and the third string on the other MPPTs.
There are a couple of drawbacks with doing things this way with some losses due to West and East hitting their straps at different times of day so one string is continually pulling the other down a bit, but it's only a few percent overall.

It is however a feature that comes much more into play with larger (8-10kW) inverter design.

Would I recommend Fronius?

Absolutely. First class product, awesome reputation, fully justified, and great Australian based support as well.
European made. Ticks many boxes.
Should they make their own batteries? Yes. Whilst they play nicely with Chinese BYD batteries, it would be much better if Fronius made their own.
Are they more expensive than Huawei, Sungrow, etc? Yes, and usually by quite a bit.
Do we enjoy installing and supporting Fronius and BYD batteries? Yes, effortless, and almost no cause to return to fix faults.

Do I think Fronius are the best inverter? No, I don't, or at least, I can think of many situations where they aren't the best solution.

Fronius Primo (single phase) brochure

Fronius Symo (three phase) brochure

Fronius Primo GEN24Plus hybrid brochure

Fronius Symo 6-10kW GEN24Plus hybrid brochure

Fronius Symo 3-5kW GEN24Plus hybrid brochure

(08) 6102 2527

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This review was written by Andrew MacKeith, Solar4Ever service manager since 2011.