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Installers & partners

Fronius Primo UL

The communicative inverter for private households.

The Fronius Primo inverter series has been specially developed for the demands of the North American market. With power categories from 3.8 to 15 kW, the single-phase, transformerless device is the perfect inverter for private households. Its innovative SuperFlex Design provides maximum flexibility in system design, while the SnapINverter mounting system makes installation and maintenance as easy as possible. The communication package included as standard, with WLAN, energy management, several interfaces and much more besides, makes the Fronius Primo a communicative inverter for home owners. Standard equipment also includes a built-in arc detector (AFCI = Arc Fault Circuit Interrupter), in keeping with all other North American SnapINverters.
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Product details


512 mm
751 mm
227,5 mm
Weight incl. packaging45 kg
Dimension (width)510,54 mm
Dimension (height)723,9 mm
Dimension (depth)226,06 mm
Weight37,4 kg
Protection classNEMA 4X
Night time consumption< 1 W
Inverter topologyTransformerless
CoolingVariable speed fan
Elevation4000 m (13120 ft) with a max. input voltage of 1000 V
Certificates and compliance with standardsUL 1741-2010 Second Edition (incl. UL1741 Supplement SA 2016-09 for California Rule 21), UL1998 (for functions: AFCI, RCMU and isolation monitoring), IEEE 1547-2003, IEEE 1547.1-2003, ANSI/IEEE C62.41, FCC Part 15 A & B, NEC 2017 Article 690, C22. 2 No. 107.1-16, UL1699B Issue 2 -2013, CSA TIL M-07 Issue 1 -2013
DC connection terminals4x DC+1, 2x DC+2 and 6x DC- screw terminals for copper (solid / stranded / fine stranded) or aluminum (solid / stranded)
AC connection terminalsScrew terminals 12 - 6 AWG
Revenue Grade MeteringOptional (ANSI C12.1 accuracy)
UL safety standards & network regulationsUL 1741-2015, UL 1998, UL 1699B Issue 2-2013
Interference emission classB


Number of MPPT2
Recommended PV Power (kWp)8.0 - 15.5 kW
Max. usable input current33,0 / 18,0 A
Max. usable input current total (MPPT1 + MPPT2)
51 A
Max. array short circuit current (1.5 * Imax)
49,5 / 27 A
Nominal input voltage
655 V
Operating voltage range80 - 1000 V
MPP Voltage Range
220 - 800 V
Max. input voltage (Udc max)
1000 V
Integrated DC string fuse holders4- and 4+ for MPPT 1 / no fusing required on MPPT 2


Max. output power 240 V9995 VA
Max. output power 208 V9995 VA
Output configuration
1~ NPE 208 / 240 V
Frequency range45 - 66 Hz
Nominal operating frequency60 Hz
Total harmonic distortion< 2,5 %
Power factor range
0 - 1 ind,/cap,
Max. continuous output current 240 V41,6 A
Max. continuous output current 208 V48,1 A
OCPD/AC breaker size 208 V70 A
Max. efficiency97,9 %
CEC efficiency 240 V96,5 %


DC reverse polarity protectionYes
Anti islandinginternal; in accordance with UL 1741-2016-09, IEEE 1547-2003 and NEC 2017
Over temperature protectionOutput power derating / Active cooling
Rapid shutdown compliantYes (according to NEC 2014)
Ground fault protection with isolation monitor interrupterYes
DC disconnectYes


Wi-Fi / Ethernet LANWireless standard 802.1 1 b/g/n / Fronius Solar.web, SunSpec Modbus TCP, JSON
USB (type A socket)Datalogging and inverter update possible via USB
2x RS422 (RJ45 socket)Fronius Solar Net
Datalogger and webserverIncluded
Serial RS485SunSpec Modbus RTU
6 inputs and 4 digital I/OsLoad management; signaling, multipurpose I/O

SnapINverter technology

The SnapINverter generation of inverters features a simple, standardised mounting system, making installation and maintenance easier than ever. A special feature in the design of the device is that the connection area is separate from the power stage set compartment, with both being installed separately. The remarkably light connection area and all its cabling is fitted to the wall first, followed by the power stage set. The innovative hinged system makes installation and servicing extremely user-friendly. The inverter is simply placed in the wall bracket and then secured. This means that it is not necessary to remove the entire inverter for servicing, just the power stage set. All the cabling remains in place.

Integrated data communication

We are the first inverter manufacturer to offer a data communication package with fully integrated datalogging, WLAN, Ethernet, energy management, web server and a range of interfaces. The inverter is connected to the internet by network cable or WLAN - without additional cabling - and grants you the perfect overview of how the PV system is operating. Connection to third-party components is provided by means of interfaces such as Modbus TCP SunSpec, Modbus RTU SunSpec or Fronius Solar API (JSON). The open interfaces can also be operated in parallel to the Fronius Solar.web.

SuperFlex Design

The Fronius SuperFlex Design is an ingenious combination of technical performance attributes that make designing your PV system not only extremely simple, but also incredibly flexible. The key performance factors of the SuperFlex Design are two MPP trackers, together with a high system voltage and wide DC input voltage range. Every DC input, and therefore every MPP tracker, is able to accommodate the entire nominal output of the inverter. Regardless of whether the inverter has to cope with different roof orientations, shading of one or two strings, or the use of residual modules: a Fronius inverter featuring integrated SuperFlex Design will satisfy every conceivable operational PV system planning scenario using just a single inverter model.

Smart Grid Ready

Fronius inverters are ready for the Smart Grid of tomorrow. The inverters are optimally equipped to meet the technical requirements of grids in the future. A series of smart functions, known as Advanced Grid Features, are built into the devices. They include a number of control functions for optimum feed-in of reactive power and effective power. These functions are designed to enable stable grid operation even when the PV system density is very high and to prevent unwanted interruptions to feed-in and associated yield losses if grid parameters exceed the thresholds. Fronius inverters therefore help to guarantee the yield of a PV system. Furthermore, where feed-in limits are imposed, Fronius inverters can provide dynamic feed-in control with self-consumption taken into account. Just connect the meter and set the feed-in limit!

Arc Fault Circuit Interruption Integrated

The Fronius Arc Fault Circuit Interruption (AFCI) makes each inverter NEC 2011 compliant and maintains some of the most civilized, integrated technology available today. Ensuring the utmost safety, AFCI shuts down the inverter in the event of an arc fault.

Active Cooling

Active cooling technology relies on one or more fans, which not only avoid hot spots, but also regulate the air circulation inside the inverter, thus keeping the temperature of the power electronics low. This has a positive effect on the service life of the devices, optimises yields and reduces costs. At Fronius, active cooling is supplied as standard in all devices.

Digital Operating Instruction

Clear HTML version of the operating instructions. Mobile and optimised for every device.


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