The Primo and Symo are transformerless solar inverters from Fronius with a revolutionary snap-in design, dual MPPT inputs, and a wide operating voltage range. While the Primo is a single-phase inverter outputting 3 – 8.2 kW (ideal for households), the three-phase Symo inverter reaches 3 – 20 kW and is suitable for all system sizes.

Your inverter is one of the most critical parts of your solar PV system. But it’s also the component that’s most failure-prone. As such, you want to have a high-quality solar inverter when going solar.

The Primo and Symo are some of Australia’s most popular solar inverters manufactured by the leading inverter brand Fronius. Since their release, these inverters have developed a sizable following and are routinely praised as high-performing, reliable, and safe devices.

But are the Primo and Symo inverters all that their hype suggests? This review will answer that question and more.

Read on to discover:

  • What are the Fronius Primo and Symo inverters?
  • What are the technical specifications of the Primo and Symo?
  • What are the key features of the Fronius Primo and Symo?
  • Are the Fronius Primo and Symo inverters reliable and safe?
  • Can you retrofit a battery to the Fronius Primo and Symo?

Let’s get right into it!

What are the Fronius Primo and Fronius Symo Inverters?

The Fronius Primo is a single-phase transformerless inverter ideal for private households. The Fronius Symo is a three-phase transformerless inverter suitable for every system size.

The inverters are manufactured by Fronius, a leading inverter brand worldwide. Günter Fronius laid the foundations for what would become a global company in 1945 when the company focused on developing battery charging systems. It has since expanded into welding transformers.

Fronius entered the solar industry in 1992 when it formed Fronius Solar Energy. The company’s first milestone was the launch of its first inverter (the Fronius Sunrise) in 1995. Its second major success was the launch of its IG inverters in 2001.

However, the company’s breakthrough in 2014 placed it in the upper echelon of inverter manufacturers. This was the introduction of the SnapINverter technology; the Primo and Symo inverter models both feature this SnapINverter function. Other devices with this feature include the Fronius Eco and Fronius Galvo inverters.

The Fronius Primo and Symo inverters are engineered, designed, and manufactured in Austria. They feature the company’s innovative SuperFlex Design, and also ship with Ethernet internet connection, meter interface, and easy integration with third-party components, making them some of the most user-friendly inverters on the market.

Fronius Primo and Fronius Symo Solar Inverter Range

Both Fronius solar inverters are available in various sizes, so you’ll have no problem finding one with the output that you require.

The Fronius Primo inverter has eight size options as follows:

  • Fronius Primo 3.0-1,
  • Fronius Primo 3.5-1,
  • Fronius Primo 3.6-1,
  • Fronius Primo 4.0-1,
  • Fronius Primo 4.6-1,
  • Fronius Primo 5.0-1,
  • Fronius Primo 6.0-1, and
  • Fronius Primo 8.2-1.

On the other hand, the Fronius Symo inverter has twelve size options:

  • Fronius Symo 3.0-3-S/M,
  • Fronius Symo 3.7-3-S/M,
  • Fronius Symo 4.5-3-S/M,
  • Fronius Symo 5.0-3-M,
  • Fronius Symo 6.0-3-M,
  • Fronius Symo 7.0-3-M,
  • Fronius Symo 8.2-3-M,
  • Fronius Symo 10.0-3-M,
  • Fronius Symo 12.5-3-M,
  • Fronius Symo 15.0-3-M,
  • Fronius Symo 17.5-3-M, and
  • Fronius Symo 20.0-3-M.

What are the Fronius Primo and Symo Inverters’ Prices?

The costs of the Fronius Symo and Fronius Primo inverters vary depending on the retailer and their availability.

Having said that, should expect the Primo inverters to cost you as follows:

Fronius Primo InverterPrice Range
Fronius Primo 3.0-1$1,600 – $1,800
Fronius Primo 3.5-1$1,750 – $1,900
Fronius Primo 3.6-1$1,850 – $2,000
Fronius Primo 4.0-1$1,900 – $2,100
Fronius Primo 4.6-1$2,000 – $2,250
Fronius Primo 5.0-1$2,200 – $2,500
Fronius Primo 6.0-1$2,700 – $3,000
Fronius Primo 8.2-1$3,000 – $3,300

Meanwhile, the Symo inverters can be found in the price range below:

Fronius Symo InverterPrice Range
Fronius Symo 3.0-3-S$1,800 – $1,900
Fronius Symo 3.0-3-M$1,850 – $2,000
Fronius Symo 3.7-3-S$1,950 – $2,100
Fronius Symo 3.7-3-M$2,000 – $2,200
Fronius Symo 4.5-3-S$2,100 – $2,250
Fronius Symo 4.5-3-M$2,150 – $2,300
Fronius Symo 5.0-3-M$2,250 – $2,450
Fronius Symo 6.0-3-M$2,400 – $2,700
Fronius Symo 7.0-3-M$2,800 – $3,000
Fronius Symo 8.2-3-M$2,900 – $3,100
Fronius Symo 10.0-3-M$3,250 – $3,500 
Fronius Symo 12.5-3-M$3,900 – $4,200
Fronius Symo 15.0-3-M$4,200 – $4,500
Fronius Symo 17.5-3-M$4,400 – $4,700
Fronius Symo 20.0-3-M$4,900 – $5,200

What are Primo and Symo Inverters’ Technical Specifications?

The datasheets of the Fronius Primo and Fronius Symo solar inverters illustrate that they are some of the finest inverters on the market.

The specs of the Fronius Primo inverter are as follows:

Input DataPrimo 3.0-1Primo 3.5-1Primo 3.6-1Primo 4.0-1Primo 4.6-1Primo 5.0-1Primo 6.0-1Primo 8.2-1
Number of MPP trackers22222222
Max input current12 A / 12 A12 A / 12 A12 A / 12 A12 A / 12 A12 A / 12 A12 A / 12 A18 A / 18 A18 A / 18 A
Max array short circuit current18 A / 18 A18 A / 18 A18 A / 18 A18 A / 18 A18 A / 18 A18 A / 18 A27 A / 27 A27 A / 27 A
DC input voltage80 – 1000 V80 – 1000 V80 – 1000 V80 – 1000 V80 – 1000 V80 – 1000 V80 – 1000 V80 – 1000 V
Feed-in start voltage80 V80 V80 V80 V80 V80 V80 V80 V
Usable MPP voltage range80 – 800 V80 – 800 V80 – 800 V80 – 800 V80 – 800 V80 – 800 V80 – 800 V80 – 800 V
Number of DC CONN2 + 22 + 22 + 22 + 22 + 22 + 22 + 22 + 2
Max PV generator output 4.5 kW5.3 kW5.5 kW6 kW6.9 kW7.5 kW9 kW12.3 kW
Output DataPrimo 3.0-1Primo 3.5-1Primo 3.6-1Primo 4.0-1Primo 4.6-1Primo 5.0-1Primo 6.0-1Primo 8.2-1
AC nominal output3.0 kW3.5 kW3.68 kW4 kW4.6 kW5.0 kW6.0 kW8.2 kW
Max output power3000 VA3500 VA3680 VA4000 VA4600 VA5000 VA6000 VA8200 VA
AC output current13 A15.2 A16 A17.4 A20 A21.7 A26.1 A35.7 A
AC voltage range180 – 270 V180 – 270 V180 – 270 V180 – 270 V180 – 270 V180 – 270 V180 – 270 V180 – 270 V
Grid connection1~ NPE 220 / 230 V1~ NPE 220 / 230 V1~ NPE 220 / 230 V1~ NPE 220 / 230 V1~ NPE 220 / 230 V1~ NPE 220 / 230 V1~ NPE 220 / 230 V1~ NPE 220 / 230 V
Frequency
(freq. range)
50 Hz / 60 Hz
(45 – 65 Hz)
50 Hz / 60 Hz
(45 – 65 Hz)
50 Hz / 60 Hz
(45 – 65 Hz)
50 Hz / 60 Hz
(45 – 65 Hz)
50 Hz / 60 Hz
(45 – 65 Hz)
50 Hz / 60 Hz
(45 – 65 Hz)
50 Hz / 60 Hz
(45 – 65 Hz)
50 Hz / 60 Hz
(45 – 65 Hz)
Efficiency Primo 3.0-1Primo 3.5-1Primo 3.6-1Primo 4.0-1Primo 4.6-1Primo 5.0-1Primo 6.0-1Primo 8.2-1
Max efficiency98.0%98.0%98.0%98.1%98.1%98.1%98.1%98.1%
European efficiency96.1%96.8%96.8%97.0%97.0%97.1%97.3%97.5%
General DataPrimo 3.0-1Primo 3.5-1Primo 3.6-1Primo 4.0-1Primo 4.6-1Primo 5.0-1Primo 6.0-1Primo 8.2-1
Dimensions (HxWxD)645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm
Weight21.5 kg21.5 kg21.5 kg21.5 kg21.5 kg21.5 kg21.5 kg21.5 kg
Degree of protectionIP 65IP 65IP 65IP 65IP 65IP 65IP 65IP 65
Inverter designTransformerlessTransformerlessTransformerlessTransformerlessTransformerlessTransformerlessTransformerlessTransformerless
CoolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air cooling
Ambient temperature range-40 to +55 °C-40 to +55 °C-40 to +55 °C-40 to +55 °C-40 to +55 °C-40 to +55 °C-40 to +55 °C-40 to +55 °C
Permitted humidity0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%
InstallationIndoor and outdoor Indoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoor

Technical specs for the Fronius Symo 3.0 – 4.5 range are shown below:

Input DataSymo 3.0-3-SSymo 3.7-3-SSymo 4.5-3-SSymo 3.0-3-MSymo 3.7-3-MSymo 4.5-3-M
Number of MPP trackers111222
Max input current16.0 A16.0 A16.0 A16.0 A / 16.0 A16.0 A / 16.0A16.0 A / 16.0 A
Max array short circuit current24.0 A24.0 A24.0 A24.0 A / 24.0 A24.0 A / 24.0 A24.0 A / 24.0 A
DC input voltage150 – 1000 V150 – 1000 V150 – 1000 V150 – 1000 V150 – 1000 V150 – 1000 V
Feed-in start voltage200 V200 V200 V200 V200 V200 V
Usable MPP voltage range150 – 800 V150 – 800 V150 – 800 V150 – 800 V150 – 800 V150 – 800 V
Number of DC connections3332+22+22+2
Max PV generator output 6.0 kW7.4 kW9.0 kW6.0 kW7.4 kW9.0 kW
Output DataSymo 3.0-3-SSymo 3.7-3-SSymo 4.5-3-SSymo 3.0-3-MSymo 3.7-3-MSymo 4.5-3-M
AC nominal output3.0 kW3.7 kW4.5 kW3.0 kW3.7 kW4.5 kW
Max output power3.0 VA3.7 VA4.5 VA3.0 VA3.7 VA4.5 VA
AC output current4.3 A5.3 A6.5 A4.3 A5.3 A6.5 A
AC voltage range150 – 280 V150 – 280 V150 – 280 V150 – 280 V150 – 280 V150 – 280 V
Grid connection3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V
Frequency (frequency range)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)
EfficiencySymo 3.0-3-SSymo 3.7-3-SSymo 4.5-3-SSymo 3.0-3-MSymo 3.7-3-MSymo 4.5-3-M
Max efficiency98.0%98.0%98.0%98.0%98.0%98.0%
European efficiency 96.2%96.7%97.0%96.5%96.9%97.2%
General DataSymo 3.0-3-SSymo 3.7-3-SSymo 4.5-3-SSymo 3.0-3-MSymo 3.7-3-MSymo 4.5-3-M
Dimensions (HxWxD)645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm
Weight16.0 kg16.0 kg16.0 kg19.9 kg19.9 kg19.9 kg
Degree of protectionIP 65IP 65IP 65IP 65IP 65IP 65
Inverter designTransformerlessTransformerlessTransformerlessTransformerlessTransformerlessTransformerless
CoolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air cooling
Ambient temperature range-25 to + 60 °C-25 to + 60 °C-25 to + 60 °C-25 to + 60 °C-25 to + 60 °C-25 to + 60 °C
Permitted humidity0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%
InstallationIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoor

The specs of the Fronius Symo 5.0 – 20.0 range are outlined below:

Input Data5.0-3-M6.0-3-M7.0-3-M8.2-3-M10.0-3-M12.5-3-M15.0-3-M17.5-3-M20.0-3-M
Number of MPP trackers222222222
Max input current16.0 A / 16.0 A16.0 A / 16.0 A16.0 A / 16.0 A16.0 A/ 16.0 A27.0 A / 16.5 A27.0 A / 16.5 A33.0 A / 27.0 A33.0 A / 27.0 A33.0 A / 27.0 A
Max array short circuit current24.0 A / 24.0 V24.0 A / 24.0 V24.0 A / 24.0 V24.0 A / 24.0 V40.5 A / 24.8 A40.5 A / 24.8 A49.5A / 40.5 A49.5A / 40.5 A49.5A / 40.5 A
DC input voltage150 – 1000 V150 – 1000 V150 – 1000 V150 – 1000 V200 – 1000 V200 – 1000 V200 – 1000 V200 – 1000 V200 – 1000 V
Feed-in start voltage200 V200 V200 V200 V200 V200 V200 V200 V200 V
Usable MPP voltage range150 –
800 V
150 –
800 V
150 –
800 V
150 –
800 V
150 –
800 V
150 –
800 V
150 –
800 V
150 –
800 V
150 –
800 V
Number of DC CONN2+22+22+22+23+33+33+33+33+3
Max PV generator output 10.0 kW12.0 kW14.0 kW16.4 kW15.0 kW18.8 kW22.5 kW26.3 kW30.0 kW
Output Data5.0-3-M6.0-3-M7.0-3-M8.2-3-M10.0-3-M12.5-3-M15.0-3-M17.5-3-M20.0-3-M
AC nominal output5.0 kW6.0 kW7.0 kW8.2 kW10 kW12.5 kW15 kW17.5 kW20 kW
Max output power5000
VA
6000
VA
7000
VA
8200
VA
10000
VA
12500
VA
15000
VA
17500
VA
20000
VA
AC output current7.2 A8.7 A10.1 A11.8 A14.4 A18.0 A21.7 A25.3 A28.9 A
AC voltage range150 – 280 V150 – 280 V150 – 280 V150 – 280 V150 – 280 V150 – 280 V150 – 280 V150 – 280 V150 – 280 V
Grid connection3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V3~NPE 400 V / 230 V or 3~NPE 380 V / 220 V
Frequency (freq. range)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)50 Hz / 60 Hz (45 – 65 Hz)
Efficiency 5.0-3-M6.0-3-M7.0-3-M8.2-3-M10.0-3-M12.5-3-M15.0-3-M17.5-3-M20.0-3-M
Max Efficiency98.0%98.0%98.0%98.0%98.0%98.0%98.1%98.1%98.1%
European efficiency 97.3%97.5%97.6%97.7%97.4%97.6%97.8%97.8%97.9%
General Data5.0-3-M6.0-3-M7.0-3-M8.2-3-M10.0-3-M12.5-3-M15.0-3-M17.5-3-M20.0-3-M
Dimensions (HxWxD)645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm645 x 431 x 204 mm725 x 510 x 225 mm725 x 510 x 225 mm725 x 510 x 225 mm725 x 510 x 225 mm725 x 510 x 225 mm
Weight19.9 kg19.9 kg21.9 kg21.9 kg34.8 kg34.8 kg43.4 kg43.4 kg43.4 kg
Degree of protectionIP 65IP 65IP 65IP 65IP 66IP 66IP 66IP 66IP 66
Inverter designTransformerlessTransformerlessTransformerlessTransformerlessTransformerlessTransformerlessTransformerlessTransformerlessTransformerless
CoolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air coolingRegulated air cooling
Ambient temperature range-25 to +60 °C-25 to +60 °C-25 to +60 °C-25 to +60 °C-40 to +60 °C-40 to +60 °C-40 to +60 °C-40 to +60 °C-40 to +60 °C
Permitted humidity0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%0 to 100%
InstallationIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoorIndoor and outdoor

Which Fronius Solar Inverter has Superior Output Capacity?

The Fronius Symo inverter has a higher output capacity than its Fronius Primo counterpart.

The Fronius Primo inverters have power categories ranging from 3 kW to 8.2 kW, so the largest of these single-phase inverters have an output capacity of 8.2 kilowatts. This makes the Fronius Primo inverter preferable for households.

On the other hand, the Fronius Symo has power categories ranging from 3 kW to 20 kW, meaning that the largest of these three-phase models can output 20 kilowatts. This makes it suitable for every system size. You can install the Symo in residential solar systems as well as in small commercial or industrial solar systems.

The inverter size you need for your home depends on the DC rating of your panel array, and solar panels are sized according to your power consumption. So, the best output capacity for a solar inverter is that which covers your power needs.

If you require up to 20 kW of solar power in a day, the Fronius Symo offers better output capacity. But if you need to produce only up to 8 kW of electricity daily, either Fronius inverter model will serve you well.

Which Solar Inverter has Better Efficiency?

The Fronius Primo has 98% efficiency, while the Fronius Symo has an efficiency ranging between 98% – 98.1%. As such, these two inverters are virtually identical in terms of DC-AC power conversion. 

The efficiency of inverters is the percentage of DC power flowing from the solar panels that the inverter converts to usable AC power. Highly efficient inverters ensure minimum loss of the solar energy your solar panels produce.

The efficiency of most inverters ranges from 90% to 95%. However, highly efficient inverters will have an efficiency of 95% to 98%. Thus, the 98% efficiency of the Fronius Primo and Symo means that they are some of the most capable inverters

Which Fronius Inverter has the Most MPP Trackers?

The Fronius Primo and Fronius Symo solar inverters have two MPP trackers. However, the three “S” series of the Fronius Symo (Symo 3.0-3-S, Symo 3.7-3-S, and Symo 4.5-3-S) have one MPP tracker.

Maximum Power Point (MPP) trackers help a solar system extract more energy from its PV modules. The MPP tracker scans the power output from each module and drives the operating point of the inverter to the maximum power point of the modules. Thus, MPP trackers boost energy yield from solar panels.

The dual MPPT of the Fronius inverters also allow for more flexibility during system design.

For example, if your solar system has two arrays with different string lengths or is placed at different tilt angles, you’ll need two single MPPT inverters. However, one dual MPPT inverter like the Fronius Primo and the Symo (M versions) can accommodate the installation, saving additional costs.

What are the Key Features of the Fronius Primo and Fronius Symo?

The Fronius Primo and Fronius Symo have numerous features that make them fantastic solar inverters.

These include:

  • SnapINverter technology. This is a simple mounting system that makes installation and maintenance effortless.
  • Integrated data communication. Both devices have robust data communication packages making them some of the most intuitive inverters.
  • Superflex design. This combination of technology allows for greater flexibility in your system layout.
  • Dynamic peak manager (DPM). DPM is a shade management feature that uses advanced MPP tracking to obtain the best energy harvest.
  • Smart-grid readiness. The inverters have advanced grid features for optimal grid operations.
  • Zero feed-in function. This function facilitates easy compliance with minimum feed-in requirements.
  • Active cooling. Fronius uses fans to actively force-cool the inverters to keep them within the operating temperature range. 
  • Compact and stylish design. The Fronius inverters are aesthetically pleasing with flushed sides and minimalistic exteriors.
  • Water-proof protective casing. These devices have an ingress protection rating of IP 65 (specific Symo models are even rated IP 66).
  • Transformerless design. The inverters do not have transformers making them compact, lighter, and with one more minor point of failure.

1. SnapINverter Technology 

The main feature of the Fronius Primo and Fronius Symo is the snap-in design, a standardised mounting system that makes installation and maintenance child’s play. Other Fronius inverters with the snap-in design are the Fronius Eco series and the Galvo series.

The unique feature of this snap-in design is the power stage set component that’s separate from the connection area. The connection area (and all its cabling) is fitted to the wall first during installation. Then the power stage set is snapped in using an innovative hinge system.

The arrangement is such that you slide the inverter into the wall bracket. Thus, it’s not necessary to remove the entire inverter for servicing. Instead, you only need to remove the power stage set while the cabling remains in place on the connection area that remains on the wall.

2. Integrated Data Communication

The Fronius Primo and Symo have fully integrated data logging, web server, and energy management. For example, the inverters come standard with a meter interface for feed-in management and visualising consumption.

They also come standard with WLAN and Ethernet internet connection and allow easy integration of third-party components (using interfaces like Modbus TCP SunSpec, Modbus RTU SunSpec, or Fronius Solar API).

3. Superflex Design

The Superflex design of the Fronius inverters is a combination of performance attributes that provides flexibility when designing your solar PV system.

These technical attributes are:

  • Dual MPP trackers,
  • High system voltage, and
  • Wide DC input voltage range.

The voltage range that the Fronius inverters operate by is considerable. It’s between 80 – 1000 V for the Primo. For the Symo, it’s between 150 to 1000 V (but between 200 – 1000V for the bigger sizes). This allows PV designers flexibility when sizing PV arrays.

Also, the Fronius inverters feature dual MPP trackers, allowing a single inverter for different operational PV system scenarios. For example, a single Fronius Primo or Symo will work as intended if your modules are placed on different roof orientations, use residual modules, or have a PV array with strings of different lengths.

4. Dynamic Peak Manager

The Dynamic Peak Manager is an intelligent shade management feature of the Fronius inverters. 

Shading significantly affects the performance of solar panels. However, the environment may change, causing your solar panels to suffer shading. This feature is why Fronius inverters with integrated shade management features make for such a useful combination.

The Dynamic Peak Manager uses an advanced MPP tracking algorithm that analyses the entire PV characteristic curve at regular intervals to find the global maximum power point (GMPP), even under partial shading. Thus, the system optimises power yield at the string level when there is shading.

The DPM’s string-level optimisation means you don’t need to invest in additional panel optimisers to combat shading. In essence, DPM saves you more money in the long run. It also makes your system more reliable because adding extra components increases failure points.  

5. Smart-Grid Ready 

The Fronius Primo and Symo are equipped with features that allow the inverters to communicate with the grid to ensure stable mains supply and prevent unexpected failures that could lead to yield losses.

For example, the inverters optimise effective and reactive power for maximum yield. Typically, when peaks cause grid voltage to exceed an inverter’s limit, the inverter shuts down. The Fronius smart grid feature addresses this problem by influencing effective and reactive power in a targeted manner to keep grid voltage within limits and prevent undesired shutdowns.

The three-phase Symo inverters can also ensure a stable grid by targeting asymmetrical feed. Suppose the voltage is too high in just one phase. In that case, the Symo can improve grid voltage and prevent energy losses by reducing the power in that phase while simultaneously feeding more energy to the grid in the other two phases.

6. Zero Feed-in Function

The zero feed-in function is a solution for optimum feed-in management.

An increasing number of grid operators are setting feed-in limits for grid-tied solar systems. This feature means that you will always be compliant. The inverter supplies power to the household first, then reduces the system power output to the maximum feed-in power.

You may also set the inverter so it does not feed power into the grid (zero feed-in).

7. Active Cooling

The Fronius inverters feature active cooling technology using internal fans.

These fans keep the temperature of the internal components of the inverters low. As the inverter operates and generates heat, the fans facilitate air circulation by blowing the warm air out of the inverter and sucking in cool air. This prevents heat fields and prolongs the service life of the inverters.

Active cooling is more effective than passive cooling (cooling by natural convection), which many competing inverters in the market use.

However, some argue that cooling fans are a point of failure and make the inverters more noisy than necessary.

True, these Fronius inverters hum noticeably when their fans are operating. The Primo’s noise is 65 dB during peak production, while the Symo emits between 58 – 65 dB at maximum output. That said, you wouldn’t want these inverters positioned just outside your bedroom.

The latest iteration of the Fronius SnapINverter (the Gen24) is a terrific option if noise minimalisation is a priority.

8. Compact and Stylish Design

If aesthetics are a concern, you’ll be pleasantly surprised by the Fronius Primo and Symo.

These inverters will hang beautifully on your wall when mounted with their flushed sides and white/black colour pattern. They also have minimalistic exteriors that feature only the Fronius logo, the inverter name, and a small meter interface.

The inverters are also portable as they have relatively small footprints and are lightweight. Inverters typically weigh 13.5 kg to 22.5 kg. The Fronius Primo and Symo weigh less than 22kg. Only the larger Symo models (with a power range of 10 kW – 20 kW) weigh more than 22 kg.

9. Water-Proof Protective Casing

The Fronius Primo and the smaller Symo models have an ingress protection rating of IP 65, while the larger Symo inverters (10 kW – 20 kW) have an ingress protection rating of IP 66.

The ratings indicate that the Fronius inverters have excellent sealing effectiveness against dust and water. That is, they are dust-proof and water-proof.

The “IP 65-rated” Fronius inverters are protected against dust and low-pressure jets of water, while the “IP 66-rated” inverters are protected against dust and strong water jets.

Therefore, you can install the Fronius inverters outdoors without fear of ingress penetrating them and causing damage. Given that the top inverters in the market have IP 65 ratings, you have an additional layer of security when selecting an IP 66 Fronius inverter.

10. Transformerless Design

The Fronius Primo and Symo are both transformerless inverters.

These inverters do not have the traditional transformers for stepping up voltage if necessary. Instead, they use electronic components in a complex process to step-up voltage.

The absence of a transformer in these inverters means they have fewer components. This makes them:

  • Relatively cheaper,
  • More reliable with fewer points of failure, and
  • Lighter and more compact.

The main disadvantage of transformerless inverters is that they are prone to surges. Thankfully, the Fronius inverters come with in-built surge protectors.

Which Solar Inverter has the Better Warranty?

The Fronius Primo and Fronius Symo have identical product warranties. All Fronius inverters come standard with a five years warranty. However, extending the warranty by another five (5) years is possible.

If you register your Primo or Symo inverter on Fronius Solar.web, the company will provide an additional five years warranty, bringing your total coverage period to ten years.

It’s worth noting that the average warranty period for inverters is ten years. So, the Fronius “5 + 5” years warranty is in line with industry standards.

However, the additional five-year Fronius warranty is limited, applying to only products purchased before June 30, 2022. Secondly, the additional five years of Fronius warranty covers only parts or materials needed for repairs.

Which Fronius Inverter is Safer and More Reliable?

The Fronius Primo and the Fronius Symo are equally reliable devices. The two inverters feature similar technologies for consistent safety standards. They also pass extensive in-house and independent inverter performance tests.

For example, in the comprehensive PVEL test, not only did the Fronius inverters excel, the Symo was the best performer in three categories:

  • High-temperature operation. The Symo is one of the best in the world for in-built safety mechanisms that protect components from high temperatures. 
  • Transient response. This inverter is also one of the best for grid voltage response, frequency changes, and preventing freak trip events.
  • Ground and Arc fault tests. Lastly, the inverter is one of the best in the world for detecting safety issues like arc faults.

Some of the reliability and safety features of the Fronius Primo and Symo are: 

  • DC disconnector. The Fronius Primo and Symo include an integrated DC isolator (DC disconnector), a device that disconnects the inverter from the solar panels when there is a problem.  
  • Automated insulation monitoring. The Fronius inverters are some of the best for PV system diagnostics. For example, the system performs an insulation check every day (even before the inverter starts working). If any fault is detected, the inverter displays error codes and automatically shuts off.
  • Protective casing. Because of the water-proof “IP 65 / IP 66” rated casing of the Fronius inverters, moisture ingress cannot degrade connections in junction boxes, switches, and connectors.
  • Effective active cooling system. Internal fans for cooling reduce hot spots (heat fields) that damage heat-sensitive inverter components.
  • Dynamic Peak Manager. The advanced MPP tracking algorithm of the Fronius inverters does the work of panel-level power optimisers. As a result, you don’t need to add these additional components to your system and introduce more failure points.

Are These Inverters CEC-Approved?

The Fronius Primo and Symo are both on the CEC list of approved inverters.

This means that these inverters are high-performing and secure inverters. The Clean Energy Council (CEC) is the regulator of Australia’s solar industry. Its objectives include improving standards and maintaining integrity in the industry. One way it does this is to recommend high-performing solar products like inverters and modules.

The CEC rigorously tests inverters and lists those it deems fit for use. These CEC-approved inverters are safe for installation anywhere in Australia.

Because the Primo and Symo are CEC-approved inverters, you will also qualify for federal solar subsidies like the Small-scale Technology Certificates (STCs) when you utilise them in your solar project. Another requirement for claiming STCs is that CEC-approved solar installers like Instyle Solar must install your system. 

Can you Retrofit a Battery to the Fronius Solar Inverters?

You can retrofit a battery to a solar PV system that features the Fronius Primo or Symo inverter. However, because neither of these models is a hybrid inverter, any solar system using them is not “battery-ready” and requires a separate battery inverter for retrofitting a battery. 

Having battery storage and a solar system delivers power to your household both during the day (when the panels are operating) and at night (when they are inactive). Any excess solar energy during the day is stored in the battery for use at night. A battery storage system can also supply backup power during a grid outage.

A “battery-ready” solar system uses a hybrid inverter, and adding a battery system later is simple. A hybrid inverter combines a solar inverter and a battery inverter. The “solar inverter part” converts DC power from the solar panels to AC for the household appliances. In contrast, the “battery inverter part” converts AC power from the house to DC power for storage in the battery.

The Primo and Symo are traditional solar inverters. To retrofit a battery to a system using either of these inverters, you’ll need to add a battery inverter to form an AC coupled energy storage system.

If a “battery ready” system is at the top of your priorities list, there are Fronius hybrid inverters available, such as the Fronius Symo Hybrid.

Which Fronius Solar Inverter is Better? Our Opinion

The Fronius Primo and Fronius Symo are both incredible solar inverters in terms of performance, reliability, and safety. It all depends on your needs and home connection.

The main difference between the Primo and Symo is that the Primo is a single-phase inverter with sizes up to 8.2 kW, while the Symo is a three-phase inverter with sizes up to 20 kW. Thus, the Primo is best for private households, while the application of the Symo ranges from private homes to small commercial projects.

That said, if you have low electricity requirements, the Primo is more suitable if you have a single-phase connection, while the Symo is a better option if you have a three-phase connection. But if you have a high electricity requirement, you’ll need three-phase power, making the Symo your first choice.

Inverter TypeFronius PrimoFronius Symo
Home connectionSingle-phaseThree-phase
Energy requirementLowHigh

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