EG4 | FlexBOSS21 16kw AC Hybrid Inverter | 48V Split Phase | 21kW PV Input | V1.1

FlexBOSS21 16kW AC Hybrid Inverter | 48V Split Phase | 21kW PV Input | V1.1

Powerful. Scalable. Intelligent.
The EG4 FlexBOSS21 (V1.1) is a high-performance 48V split-phase hybrid inverter designed to meet the demands of modern solar energy systems. With 21kW PV input capacity, three independent MPPTs, and the ability to parallel up to 16 units, this hybrid inverter delivers robust power for both residential and commercial applications.

Whether operating off-grid, grid-tied with backup, or in full grid sell-back mode, the FlexBOSS21 provides seamless integration, smart energy management, and reliable performance. It also pairs effortlessly with GridBOSS ESS and supports closed-loop communication with compatible battery systems.

Note: LCD Display Kit sold separately.

Key Features

• Versatile Operating Modes
  Supports off-grid operation, grid-tied with backup, or full grid sell-back—giving you maximum flexibility for any energy application.

• High Voltage PV Input
  Accepts up to 600V DC input, reducing cable size, minimizing losses, and streamlining installation.

• Triple MPPT Design
  Offers greater solar harvesting efficiency and system design flexibility.

• Scalable Power
  Supports up to 16 units in parallel, enabling massive system expansion up to 256kW AC output.

• Remote Monitoring & Control
  Built-in Wi-Fi for real-time system monitoring and configuration through a user-friendly interface.

• Battery Compatibility
  Integrates with lithium and other battery chemistries using closed-loop communication for enhanced safety and performance.

• Advanced Safety Features
  Includes arc fault protection, ground fault detection, and built-in rapid shutdown for NEC 2020 compliance.

Technical Specs:

• AC Input Range: 120/240VAC or 120/208VAC (Split-phase)

• Power Output: 16kW continuous from PV with a 24kW surge capacity

• Unit Dimensions: 29.5" x 20.5" x 11.2"

• Weight: 88 lbs

• Warranty: 10-Year coverage on core components

Why Choose the FlexBOSS21?

The FlexBOSS21 delivers outstanding performance, intelligent features, and robust safety in a compact package—ideal for those seeking dependable energy independence. Its remote capabilities and scalable design make it suitable for both residential and commercial systems.

Unlock the Full Potential of Your Power System

Take your energy setup to the next level with the EG4 FlexBOSS21—an inverter built to handle demanding conditions while keeping you in full control.

EG4 GridBOSS Breaker Details

Each EG4 GridBOSS (V2.1) includes:

• (1) 90A Breaker – Only compatible with the EG4 FlexBOSS21

• Smart Port Breakers: Available in 30A, 40A, 60A, and 80A ratings

Additional Breaker Notes:

• 70A Breaker (sold separately) is required for use with the EG4 18kPV Hybrid Inverter.

• 50A Breaker (sold separately) is required for use with the EG4 12kPV Hybrid Inverter.

• 125A Breaker (sold separately) is compatible with both the Smart Port and Gen Port.

What's Included

(1) Hybrid Inverter  
(1) Wi-Fi Dongle  
(1) Wall Mount Template  
(2) 1” CTs  
(1) Battery Communication Cable (2m, Orange)  
(1) Parallel Communication Cable (2m, Grey)  
(2) L Brackets  
(6) Expansion Bolts  
(4) Phillips Head Screws (M5×10)  
(4) Phillips Head Screws (M3×10)  
(6) Self-Tapping Screws  
(4) RJ45 Terminals  

Specifications & Manuals

Spec Sheet

User Manual

Warranty

UL 1741 Certificate of Compliance

Warranty

10-Year Warranty

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Warranty Registration and Validity

Your warranty must be registered within the first year of purchase or you must provide proof of purchase from Solar Guys Pro, an EG4 authorized distributor, for it to remain valid. Failure to register or provide proof of purchase may result in an invalidated warranty. This limited warranty applies to the original purchaser and is transferable one time only if the product remains in the original installation location. All parts exchanges are covered during the warranty period, but replacement shipping charges may apply outside the continental US.

Warranty Exclusions: EG4 Electronics is not obligated under this limited warranty for products subjected to the following conditions (including but not limited to):

1) Damages incurred during installation, reinstallation, or removal
2) Poor workmanship by an individual, installer, or firm
3) Damages from mishandling or inappropriate environmental exposure
4) Damages from improper maintenance or operating outside specified conditions
5) Tampering, altering, or disassembly of the product
6) Using the product in unintended applications
7) Damages from lightning, fire, flood, earthquake, riots, or acts of God
8) Products with altered, defaced, or removed serial numbers
9) Unauthorized firmware updates, upgrades, or patches
10) Damages from voltage or current spikes due to open-loop lithium battery communications

EG4 product warranty is a limited warranty – EG4’s liability in the event of a product defect is limited to repair or replacement under the terms of this warranty. EG4 is not responsible for any additional or indirect damages arising from the product malfunction. This includes incidental or consequential damages, such as loss of revenue, profits, or time. EG4 is not liable for any direct or indirect loss of life, bodily injury, illness, or death arising from misuse or mishandling of the product, whether caused by negligence or otherwise.

Return Policy

For returns, please contact us at: 571-350-0146 or email us at: info@solarguyspro.com. To view our return policy, please go: HERE

Warranty Claims Procedure

To initiate a warranty claim, contact our customer service team via phone at 571-350-0146 or email at info@solarguyspro.com to request an RMA. Warranty claims can also be initiated through the official EG4 website (https://eg4electronics.com/warranty).

Contact Information:
- Email: info@solarguyspro.com
- Phone: +1571-350-0146

Warranty Periods

- Inverters:
  - 10 years on 18kPV
  - 3 years (5 years extended warranty with EG4 batteries) on 3k, 6k, 6.5k, and 8k
- Batteries:
  - 10 years on LL
  - 5 years on LifePower (10 years extended when used with 18kPV)
  - 5 years on waterproof
  - 5 years on indoor wall mount
  - 10 years on outdoor wall mount
- Mini Split Air Conditioning:
   - 5 years on EG4 Hybrid AC/DC 12K BTU Mini Split
   - 5 years on EG4 Hybrid AC/DC 24K BTU Mini Split
   - 5 years on EG4 9K AC Mini Split
   - 5 years on EG4 12K AC Mini Split