Fronius Primo 11.4kW Inverter 11.4-1-208-240

The Fronius Primo 11.4-1 is an 11,400W single-phase transformerless grid-tie inverter engineered for residential and light-commercial solar installations requiring 208V or 240V single-phase output. Available through A1 SolarStore, it combines dual independent MPPT trackers, a 1,000V maximum DC input, and the Fronius Solar.web monitoring platform in a NEMA 4X-rated enclosure that installs indoors or outdoors with equal ease.

Key specifications

• Rated AC output power: 11,400 VA @ 208V / 11,400 VA @ 240V
• Maximum continuous output current: 54.8A @ 208V / 47.5A @ 240V
• OCPD / AC breaker size: 70A @ 208V / 60A @ 240V
• Maximum DC input voltage: 1,000V | Nominal input voltage: 660V
• MPP voltage range: 240–800V | DC startup voltage: 80V | Operating voltage range: 80–1,000V
• Dual independent MPPT trackers: MPPT 1 up to 33.0A / MPPT 2 up to 18.0A; combined max input current: 51A
• Recommended PV array size: 9.1–13.7 kWp
• Maximum efficiency: 96.7% | CEC efficiency: 96.0% @ 600V / 96.5% @ 1,000V
• Total harmonic distortion: <2.5%
• Power factor range: 0–1 ind./cap.
• Inverter topology: Transformerless
• Protection rating: NEMA 4X — rated for indoor and outdoor installation
• Dimensions (W×H×D): 20.1 × 28.5 × 8.9 in. | Weight: 82.5 lbs.
• Operating temperature: -40°F to 140°F (-40°C to 60°C)
• Cooling: Variable-speed fan | Nighttime consumption: <1W
• Certifications: UL1741, UL1741 SA (California Rule 21 / Hawaii Rule 14H), UL1998, UL1699B, IEEE 1547, NEC 2017 Article 690, CSA C22.2, FCC Part 15 A & B
• Communication interfaces: Wi-Fi / Ethernet LAN, RS485 (SunSpec Modbus RTU), 2× RS422 (Fronius Solar Net), USB, 6 I/O ports for load management
• Integrated datalogger and webserver: Included standard
• Revenue-grade metering: Optional, ANSI C12.1 accuracy

Dual MPPT enables complex roof designs

Unlike single-MPPT string inverters that force all panels onto a single DC bus, the Primo 11.4-1 runs two fully independent maximum power point trackers — MPPT 1 at up to 33A and MPPT 2 at up to 18A. This means two strings with different orientations, tilt angles, or shading profiles can each operate at their own optimal voltage without dragging down the other. A south-facing array and an east- or west-facing array can feed the same inverter without the production losses typical of a forced single-string compromise. The wide 240–800V MPP range also accommodates longer strings and a broader range of module configurations than narrower-window competitors.

Monitoring, commissioning, and serviceability

The Primo 11.4-1 ships with a built-in datalogger, webserver, and Wi-Fi/LAN connectivity — no external monitoring gateway is required. System data streams to the Fronius Solar.web platform for real-time and historical performance access from any browser or the mobile app. The RS485 port supports SunSpec Modbus RTU for integration with third-party monitoring systems and smart meters. For installers, Fronius' SnapINverter hinge mounting system allows the inverter to pivot outward on its wall bracket for single-technician PCB access without fully removing the unit from the wall — a meaningful advantage for any service call after installation.

Application scenarios

• Residential systems up to 13.7 kWp: The primary fit — homes with higher consumption or large roof areas where an 11.4kW single-phase inverter avoids the cost and permitting complexity of a three-phase unit.
• Multi-orientation residential rooftops: Dual MPPT allows south east/west string combinations without production compromise.
• California and Hawaii grid-tie installations: UL1741 SA certification confirms Rule 21 and Rule 14H advanced inverter function compliance out of the box.
• Light commercial and ADU applications: 208V compatibility makes the Primo 11.4-1 usable on commercial single-phase 208V services common in mixed-use and multi-unit buildings.
• High-altitude installations: Rated to 13,123 ft. (4,000m) elevation — suitable for mountain-state residential projects.

System compatibility

The Fronius Primo 11.4-1 is a transformer-less, ungrounded string inverter compatible with any standard crystalline or thin-film PV module string configured within the 240–800V MPP range and below the 1,000V maximum DC input. It is optimizer-agnostic and works with or without DC power optimizers, including SolarEdge, Tigo, or Maxim — though it does not require optimizers to function. DC conductors connect via screw terminals accepting AWG 14–6 copper or aluminum directly, with an optional input combiner for AWG 4–2 runs. AC output uses screw terminals accepting AWG 10–6 copper or aluminum (AWG 14–6 for copper solid/stranded). The Fronius Rapid Shutdown Box is the recommended companion device for NEC 690.12 rapid shutdown compliance outside the PV array boundary. Arc fault circuit interruption (AFCI), ground fault protection with isolation monitor, DC reverse polarity protection, and anti-islanding are all integrated as standard.

Why choose the Fronius Primo 11.4-1?

Most competing residential string inverters at this power level either cap DC input at 600V, offer a single MPPT tracker, or require a separate monitoring gateway — adding hardware cost and installation complexity. The Primo 11.4-1 addresses all three gaps: a 1,000V DC input reduces string wiring costs, dual independent MPPT unlocks multi-orientation roof designs, and the built-in datalogger with Solar.web eliminates the need for an add-on communications kit. For installers who need a reliable, fully certified, and field-serviceable single-phase inverter at the 11kW tier, it is a consistently specified choice.