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EG4 FlexBOSS18 Hybrid Inverter

EG4 FlexBOSS18 13kW AC Hybrid Inverter | 48V Split Phase | 18kW PV Input
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$3,199.00
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$3,199.00
$2,799.00
$2,799.00 - $2,799.00
$2,799.00
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EG4 FlexBoss18 Manual & Spec Sheet

View Manual HERE
View Spec Sheet HERE

UL1741 Certified Hybrid Inverter

EG4 FlexBOSS18: All-In-One Hybrid Power Without the All-In-One Price

The EG4 FlexBOSS18 is a 48V split-phase hybrid inverter built to deliver 13kW of continuous AC output, 18kW of solar input across two MPPTs, and 10kW of battery-only output — professional-grade performance at a price that makes hybrid solar accessible for both residential and commercial installs.

It integrates directly with EG4's full battery lineup, pairs with the EG4 GridBOSS MID for simplified whole-home energy management, and can be paralleled up to 16 units for larger systems. Renewable Outdoors backs every FlexBOSS18 with a 10-year limited warranty and our Lowest Price Guarantee.

EG4 FlexBOSS18 13kW hybrid inverter
10-Year Limited Warranty
Lowest Price Guarantee
Genuine EG4 Equipment
Free Shipping on Orders $5,000+
Financing Available
Expert Support: (303) 876-7654

Why Installers and Homeowners Choose the FlexBOSS18

Serious Power Output

13kW continuous AC output with solar/grid support (10kW on battery alone), plus surge capacity up to 20,000W for half a second — enough headroom for motor startups and heavy appliances.

18kW of Solar Input

Two independent MPPTs (26A each, 120–440VDC range) let you build a larger, mixed-orientation solar array without adding a second inverter to your system.

Built for EG4 Batteries

48V nominal (40–60VDC operating range) with up to 208A of charge/discharge current, integrating directly with EG4's full battery lineup for a matched, single-brand system.

Scales With Your System

Parallel up to 16 FlexBOSS18 units for larger residential or commercial installs, or add an EG4 GridBOSS MID to eliminate extra breakers and transfer switches while unlocking time-of-use load shifting.

Engineered to Last

A NEMA 4X enclosure and EMP hardening stand up to harsh environments, with a -13°F to 140°F operating range and UL1741 certification for safety and utility interconnection.

Monitor From Anywhere

The included Wi-Fi dongle connects to the EG4 Connect app for remote monitoring and control, with cellular and Ethernet connectivity also supported.

What's Included

EG4 FlexBOSS18 hybrid inverter rear panel and connections

In the Box

  • EG4 FlexBOSS18 Hybrid Inverter
  • Wi-Fi Dongle (for EG4 Connect monitoring)
  • Wall Mount Template & Mounting Bracket
  • Two 1" Current Transformers (CTs)
  • Two L Brackets
  • Four RJ485 Terminals
  • Orange Battery Communication Cable (2m)
  • Grey Parallel Communication Cable (2m)
  • Mounting hardware (screws & expansion bolts)
  • User Manual

EG4 FlexBOSS18 Specifications

AC Output (Continuous) 13kW (54A) with solar/grid support · 10kW battery-only
Surge Output 20,000W (0.5 sec) / 15,000W (1 sec) / 13,500W (1 min)
AC Voltage 120/240V or 208V, split-phase
Max PV Input 18kW (STC)
MPPTs 2 independent channels, 26A max each
PV Voltage Range 120–440VDC operating (250–440VDC for full rated power) · 600VDC max input
Battery Voltage 51.2V nominal, 40–60VDC operating range
Max Charge/Discharge Current 208A
CEC Weighted Efficiency 97%
Battery-to-Load Efficiency 94%
Idle Consumption <60W @ 77°F (25°C)
Parallel Capability Up to 16 units
Enclosure Rating NEMA 4X, EMP-hardened
Operating Temperature -13°F to 140°F (-25°C to 60°C)
Certifications UL1741 (SA/SB), UL3141, CA Rule 21 Phase I/II/III
Monitoring & Communication Wi-Fi, Cellular, and Ethernet (Wi-Fi dongle included) via EG4 Connect app
Dimensions 30.43 × 22.28 × 11.22 in (773 × 566 × 285 mm)
Weight 115 lbs (52 kg)
Warranty 10-Year Limited Warranty

Documentation & Downloads

Want the full technical breakdown before you buy? Download the manufacturer's official spec sheet and installation manual below.

Spec Sheet Full technical specifications on a single page — output, PV input, efficiency, dimensions, and certifications. Download PDF Installation & User Manual Complete setup, wiring, safety, and configuration instructions from EG4. Download PDF

10-Year Limited Warranty

Every FlexBOSS18 we sell is backed by EG4's full manufacturer warranty.

Lowest Price Guarantee

Found it cheaper elsewhere? Call us at (303) 876-7654 before you buy.

Expert System Sizing

Call our team to size your inverter, battery bank, and solar array correctly the first time.

EG4 FlexBOSS18: Frequently Asked Questions

How much solar can I connect to the FlexBOSS18?
Up to 18kW (STC) across two independent MPPTs, each handling up to 26A. The operating voltage range is 120–440VDC, with 250–440VDC needed for full rated power, and a maximum input of 600VDC. That headroom lets you build a larger or mixed-orientation array without needing a second inverter.
What's the difference between the 13kW and 10kW output ratings?
13kW continuous output is available when the inverter has solar and/or grid support. In battery-only mode — running purely off your battery bank with no grid or solar assist — continuous output is rated at 10kW.
Can I run this off-grid, or does it require a grid connection?
The FlexBOSS18 is a hybrid inverter, so it supports grid-tied, battery-backup, and off-grid style operation. Its 10kW battery-only output means it can run your loads directly from battery power with no grid connection required.
What batteries is the FlexBOSS18 compatible with?
It's built around a 48V nominal system (51.2V, with a 40–60VDC operating range) and integrates directly with EG4's full battery lineup. Call our team and we'll help you match the right battery count and configuration to your household or business load.
Can I combine multiple FlexBOSS18 units for a larger system?
Yes. Up to 16 FlexBOSS18 units can be paralleled together, making it a realistic option for larger residential systems or commercial installations, not just single-inverter homes.
Do I need an EG4 GridBOSS MID?
It's not required, but pairing the FlexBOSS18 with a GridBOSS MID reduces installation costs, eliminates the need for extra breakers and transfer switches, and unlocks time-of-use optimization and load shifting for your system.
Does this need to be professionally installed?
Yes. EG4's own installation manual specifies that installation should be performed only by qualified, licensed personnel, following National Electrical Code (NEC) standards and your local Authority Having Jurisdiction (AHJ) requirements. A separate DC overcurrent protector or disconnect between the battery and inverter is also required. Our team can help you understand what your specific install needs.
How do I monitor the system remotely?
The FlexBOSS18 ships with a Wi-Fi dongle for the EG4 Connect app, giving you remote monitoring and control from your phone or a web browser. Cellular and Ethernet connectivity are also supported for installs without reliable Wi-Fi.
What's covered under the warranty?
EG4 backs the FlexBOSS18 with a 10-Year Limited Warranty covering manufacturing defects. As your retailer, Renewable Outdoors can also help you navigate a warranty claim if you ever need one — call us at (303) 876-7654.
Does Renewable Outdoors offer financing or price matching?
Yes. We offer financing options at checkout, and every FlexBOSS18 purchase is backed by our Lowest Price Guarantee — if you find a better price elsewhere, call us at (303) 876-7654 before you order.
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