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

EG4 FlexBOSS21 hybrid solar inverter with 21kW PV input, compact design, and advanced power gateway integration

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

$3,562.01 USD

$ $3,562.01 USD

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9+ sold

In the last 7 days

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What is your return policy?

Returns are free in the first 30 days with no restocking or processing fees, although the customer may be responsible for paying return shipping. See our complete return policy on our Shipping, Delivery, and Returns page linked in the footer of this website.

What’s covered by your return policy?

Our returns policy covers all purchases made through Portlandia Electric Supply. For warranty issues, as authorized distributors, we honor the full manufacturer warranty of ALL the brands on our website. See our complete returns and warranty policies on our Shipping, Deliver, and Returns page.

How long will it take to receive my order?

All orders are processed within 72 hours and you can expect delivery on most orders within 5-7 business days. You will receive access to our customer portal after ordering, where it is easy to track all your shipments. See our Shipping, Delivery and Returns page for more details.

What are your financing and payment options?

We offer several ways to pay to make getting your solar kit simple:

Credit Card: if the purchase is greater than your card’s limit, you can split the cost onto multiple cards as well as Paypal, financing through Affirm, and ACH/bank transfer

You can arrange financing during the checkout process, or scroll further down this page for more details. Please note, if you'd like to finance your order, you can do so instantly, right at checkout.

How does your Lifetime Customer Support work?

Our legendary lifetime customer support has helped make us the #1 online solar retailer! We have a dedicated team of solar professionals standing by to help you navigate the world of solar with ease. From selecting the perfect solar kit to installation and beyond, we provide support and expertise at every step of the journey.If you need help with ordering, shipping, troubleshooting, expanding your system, warranty issues, or anything else you have questions about for as long as you own your Portlandia Electric Supply equipment, we’ve got you covered: we’re always only a phone call or email away.

EG4® FlexBOSS21 AC Hybrid Inverter

16 kW

AC Output (Grid + PV)

21 kW

Usable PV Input

12 kW

Battery-Only Output

3 MPPT

5 Strings / 600VDC Max

Product Overview

The EG4® FlexBOSS21 is a cutting-edge split-phase hybrid inverter engineered for modern residential and small commercial solar energy systems. With an industry-leading 21kW of usable PV input (24kW max), it delivers up to 16kW of AC output when solar or grid is present, and maintains 12kW of continuous power in battery-only mode — ensuring energy supply around the clock, regardless of grid or sunlight availability.

Designed to work seamlessly with EG4's GridBOSS MID power gateway, the FlexBOSS21 supports 90A of utility feed-through at 120/240Vac, reducing installation costs and minimizing component requirements. Together with the GridBOSS, the system provides AC coupling, smart load management, and generator input — forming a scalable, cost-effective, and installation-friendly solar power solution. Backed by a 10-year manufacturer warranty.

Key Benefits

Unmatched PV Capacity: Industry-leading 21kW of usable PV input with a 24kW maximum input capacity — one of the highest in its class for a single 48V hybrid inverter unit.

Expandable & Scalable Design: Scales effortlessly from 50 to 160 amps (equivalent to full 200A service) and supports parallel stacking of up to 10 units, making it ideal for both compact residential setups and large-scale energy systems.

High Continuous Efficiency: Delivers 16kW AC output with solar active and holds 12kW without sunlight — ensuring reliable, uninterrupted energy to loads and batteries at all hours.

Smart 3-MPPT Configuration: Three MPPTs rated at 26A / 26A / 15A support up to 5 independent strings across 3 roof orientations, maximizing energy harvest from complex or mixed-orientation arrays.

GridBOSS Integration Ready: Purpose-built to pair with the EG4 GridBOSS MID power gateway, enabling AC coupling, smart load control, and generator input — all while reducing installation complexity and cost.

Compact Footprint & 10-Year Warranty: Exceptional performance in a space-saving form factor (30.4 × 22.3 × 11.2 in., 88 lbs.), backed by a full 10-year manufacturer warranty for long-term peace of mind.

How It Works

The FlexBOSS21 continuously manages power flow between solar panels, batteries, the grid, and connected loads. PV energy is prioritized for load consumption, with surplus used to charge the battery bank or export to the grid. When solar production is insufficient, the battery and grid seamlessly fill the gap — with a fast transfer time ensuring no interruption to critical loads.

Transformerless Split-Phase Topology: The high-frequency transformerless design achieves high DC-to-AC conversion efficiency while keeping the unit compact and lightweight compared to traditional transformer-based inverters.

Closed-Loop Battery Communication: Communicates via CAN/RS485 with EG4 48V lithium battery systems and other compatible brands, enabling precise state-of-charge tracking and optimized charge/discharge cycles.

90A Grid Feed-Through & Pass-Through: A dedicated 90A utility feed-through allows grid power to flow directly to loads independent of inverter output limits, easily supporting high-draw appliances including 5-ton AC units, HVAC systems, and EV chargers.

Technical Specifications

Manufacturer	EG4 Electronics
Model Name	EG4® FlexBOSS21
Inverter Type	All-in-One Hybrid \| Transformerless Split-Phase Sine Wave
AC Output (On-Grid with PV @ 240V)	16kW Continuous (66.7A @ 240V)
AC Output (On-Grid with PV @ 208V)	13.8kW Continuous
AC Output (Battery Only)	12kW Continuous (12,000VA)
Nominal AC Output Current	50A
AC Voltage Options	120/240Vac \| 120/208Vac \| 240Vac Split-Phase
Max PV Input Power (Usable)	21kW Usable / 24kW Max Input
Number of MPPTs	3 MPPTs \| Rated 26A / 26A / 15A
Max PV Strings	5 Strings (supports 3 orientations)
Battery Nominal Voltage	48 VDC
Battery Communication	CAN / RS485 (Lithium & Lead-Acid Compatible)
Grid Feed-Through / Pass-Through	90A @ 120/240Vac
Scalable Service Range	50A – 160A (Equivalent to Full 200A Service)
Parallel Stacking	Up to 10 Units
GridBOSS Compatibility	Yes — EG4 GridBOSS MID Power Gateway
Enclosure Rating	NEMA 4X (Outdoor / Wall Mount)
Dimensions (W × H × D)	30.4 × 22.3 × 11.2 inches
Weight	88 lbs.
Warranty	10-Year Manufacturer Warranty

Certifications & Compliance

Documentation

📄Spec Sheet (PDF) 📘User Manual (PDF)

● Available | Contact us for lead time and pricing

What is your return policy?

What’s covered by your return policy?

How long will it take to receive my order?

What are your financing and payment options?

We offer several ways to pay to make getting your solar kit simple:

Credit Card: if the purchase is greater than your card’s limit, you can split the cost onto multiple cards as well as Paypal, financing through Affirm, and ACH/bank transfer

You can arrange financing during the checkout process, or scroll further down this page for more details. Please note, if you'd like to finance your order, you can do so instantly, right at checkout.

How does your Lifetime Customer Support work?

EG4® FlexBOSS21 AC Hybrid Inverter

16 kW

AC Output (Grid + PV)

21 kW

Usable PV Input

12 kW

Battery-Only Output

3 MPPT

5 Strings / 600VDC Max

Product Overview

Key Benefits

Unmatched PV Capacity: Industry-leading 21kW of usable PV input with a 24kW maximum input capacity — one of the highest in its class for a single 48V hybrid inverter unit.

High Continuous Efficiency: Delivers 16kW AC output with solar active and holds 12kW without sunlight — ensuring reliable, uninterrupted energy to loads and batteries at all hours.

Smart 3-MPPT Configuration: Three MPPTs rated at 26A / 26A / 15A support up to 5 independent strings across 3 roof orientations, maximizing energy harvest from complex or mixed-orientation arrays.

How It Works

Technical Specifications

Manufacturer	EG4 Electronics
Model Name	EG4® FlexBOSS21
Inverter Type	All-in-One Hybrid \| Transformerless Split-Phase Sine Wave
AC Output (On-Grid with PV @ 240V)	16kW Continuous (66.7A @ 240V)
AC Output (On-Grid with PV @ 208V)	13.8kW Continuous
AC Output (Battery Only)	12kW Continuous (12,000VA)
Nominal AC Output Current	50A
AC Voltage Options	120/240Vac \| 120/208Vac \| 240Vac Split-Phase
Max PV Input Power (Usable)	21kW Usable / 24kW Max Input
Number of MPPTs	3 MPPTs \| Rated 26A / 26A / 15A
Max PV Strings	5 Strings (supports 3 orientations)
Battery Nominal Voltage	48 VDC
Battery Communication	CAN / RS485 (Lithium & Lead-Acid Compatible)
Grid Feed-Through / Pass-Through	90A @ 120/240Vac
Scalable Service Range	50A – 160A (Equivalent to Full 200A Service)
Parallel Stacking	Up to 10 Units
GridBOSS Compatibility	Yes — EG4 GridBOSS MID Power Gateway
Enclosure Rating	NEMA 4X (Outdoor / Wall Mount)
Dimensions (W × H × D)	30.4 × 22.3 × 11.2 inches
Weight	88 lbs.
Warranty	10-Year Manufacturer Warranty

Certifications & Compliance

Documentation

📄Spec Sheet (PDF) 📘User Manual (PDF)

● Available | Contact us for lead time and pricing

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Customer Success Stories

Troy P

EG4 off-grid base kit, Happy with my purchase.

This is the first stage of my three planned purches. I got the eg4 inverter 6000 XP base kit with six 400 watt panels and the two server rack batteries. Did a little online research and followed the instructions and it got set up without any issues. Right now I'm just running it in my garage on a single outlet and have been running dual 750 watt water distillers with it. Once I get the second inverter and a bunch more panels and batteries, I plan on attaching it to my subpanel in my house that has my lights and outlets and appliances on it. Then I'll get a soft start for my AC and blower and run it on my main panel.

Jacob B

Easy Process, Genuine Support

Trying to pick the correct solar system for your needs can be very technical and frustrating. I wanted to thank Yvhan and the Portlandia Electric supply team for their patience and helpful attitudes through multiple calls. I feel like we were able to narrow it down to what worked for me and my family. My system works great and I couldn't be happier to have picked Portlandia Electric Supply.

Patrick B

Off Grid Solar Purchase

I wanted to get an offgrid solar system for years but didn’t know where to start. I found Portlandia Electric Supply on Facebook and decided to submit a quote. Within 24 hours I had a custom proposal that was almost half the price of the companies I had previously got quotes from. My wife and I decided to order online and the kit came in a timely manner and it was an easy install. Great company to work with!

James Martin

Highly Recommend

I would like to take the time to express the outstanding service that I was provided with by Portlandia Electric Supply. They provided me with all the answers to my questions, and after reviewing our quote over the phone I felt comfortable proceeding to order my kit. It’s exactly what I needed and they were there to help us over the phone when we had questions installing it. I highly recommend others in need to choose Portlandia Electric Supply.

Brian H

Solar Kit for Mobile Work Van

As a professional videographer, I needed reliable power on the go.Portlandia Electric Supply Delta Pro and roof-mounted panels were the perfect solution. Setup was easy, and the kit included everything needed. The Delta Pro powers my cameras, lights, laptop, and a small fridge with impressive battery capacity.

Keith S

Best Tech Support

You folks have been wonderful guiding me through the ins and outs of going solar. Plus your tech guys Rod and Nelson are the absolute best. They explained all the different aspects of inverters, batteries and how to keep them in top condition. Too much more to put here… but no other company has the 100% tech support you provide for your customers!

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Great Experience

My experience with Portlandia Electric Supply has been excellent. Before the sales, they answered all my questions to assure that I got what I needed. After the sales they continued to support me with answers and help. I had a warranty issue with a unit, and it was handled as well as possible. I would recommend them to anyone looking to go solar.

Troy P

EG4 off-grid base kit, Happy with my purchase.

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James Martin

Highly Recommend

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