12KW All-In-One Off-Grid Solar Inverter FR12K-B

Solar Energy Inverter — 12KW All-In-One Split Phase 48V, FR12K-B

The FR12K-B is a 12,000W all-in-one solar energy inverter delivering pure sine wave output in both 120V single-phase and 120V/240V split-phase configurations — built for homes, small businesses, and off-grid installations that require genuine split-phase 240V capability alongside robust solar charging and flexible load management. Dual 22A MPPT trackers accept up to 13,200W of PV input, an independent generator port doubles as a secondary load output, and built-in PV Rapid Shutdown protection meets current safety code requirements. Up to six units in parallel scale total output to 72,000W.

Table of Contents

1. Product Specifications
2. Split-Phase Output Architecture
3. Dual MPPT Solar Charging
4. Generator Port and Load Management
5. PV Rapid Shutdown Protection
6. Parallel Expansion
7. Frequently Asked Questions

Product Specifications

Split-Phase Output Architecture

The FR12K-B produces true split-phase 120/240VAC output from a single unit — delivering two legs of 120V with 240V between legs. This architecture provides direct compatibility with standard North American 240V main panels, enabling the full range of residential and small commercial 240V loads — well pumps, electric water heaters, HVAC compressors, and workshop equipment — to operate from battery and solar power without external phase conversion hardware.

As a solar energy inverter designed for genuine whole-house coverage, the FR12K-B eliminates the compromises of single-phase 120V-only systems that require load shedding or phase converters to handle 240V appliances. Single-phase 120V output is equally supported for installations where split-phase is not required.

Dual MPPT Solar Charging

Two independent MPPT trackers — each rated at 22A and accepting up to 6,600W — allow the FR12K-B to manage two separate PV string orientations or tilt angles from a single unit. This is a practical advantage for rooftop installations where panels face different compass directions, or for ground-mount systems where shading affects one string but not the other.

The 99.9% MPPT tracking efficiency ensures that the maximum available power is extracted from the array under all irradiance and temperature conditions. Operating voltage range of 125–425VDC and a maximum open-circuit voltage of 500VDC provide broad compatibility with common residential string configurations using 370W, 415W, and 450W monocrystalline panels.

Both PV-only and hybrid charging modes are available, allowing the system to charge batteries exclusively from solar or to supplement solar charging with grid or generator input when the array is insufficient to meet load and charging demands simultaneously.

Generator Port and Load Management

The independent generator port on the FR12K-B can operate in two distinct modes, making it one of the more flexible load management tools available in this home inverter class:

• Generator Input Mode: Accepts AC input from a connected generator to charge the battery bank and support loads when solar resources are insufficient.
• Secondary Load Output Mode: Configured as a dedicated output for non-critical loads — allowing the inverter to cut power to secondary circuits automatically when battery state of charge reaches a defined threshold, preserving capacity for essential loads on the main output.

This dual-function port reduces the need for external contactors and load management relays in installations where load prioritisation is required.

PV Rapid Shutdown Protection

Built-in PV Rapid Shutdown (RSD) protection complies with current NEC 2017 and 2020 requirements for rooftop solar installations in jurisdictions where rapid shutdown is mandated. RSD capability reduces the risk to first responders during emergencies by de-energising the PV array conductors within seconds of activation — a requirement that is increasingly enforced in residential solar permitting across the United States.

Browse our full Solar Energy Inverters, All-In-One Off-Grid Inverters, and Split-Phase Solar Systems collections for additional options.

Frequently Asked Questions

Q: What output voltage configurations does the FR12K-B support? The FR12K-B supports 120V single-phase and 120V/240V split-phase output — selectable based on installation requirements. Split-phase output produces two legs of 120V with 240V between legs, enabling direct connection to standard North American 240V residential panels.

Q: What is the maximum PV input capacity? Two independent MPPT trackers each accept up to 6,600W, for a total PV input capacity of 13,200W. Each tracker handles up to 22A of input current with a maximum open-circuit voltage of 500VDC and an operating range of 125–425VDC.

Q: How many FR12K-B units can be connected in parallel? Up to six units can be paralleled, scaling total system output from 12kW to 72kW. All parallel units share the communication bus through RS485, CAN, or USB interfaces, and the system supports both single-phase and split-phase parallel configurations.

Q: What overload protection behaviour should I expect? The FR12K-B applies graduated overload protection based on the severity of the overload condition. Loads between 102% and 110% trigger an error and shut down after five minutes. Loads between 110% and 125% shut down after 10 seconds. Loads above 125% shut down after five seconds. After overload protection is triggered, output is restored after three minutes; five consecutive overloads disable output until the unit is manually restarted.

Q: What communication interfaces are built into the FR12K-B? Built-in interfaces include RS485, CAN, USB, and dry contact ports. WiFi and GPRS modules are available as optional external additions for remote system monitoring and performance data logging.