• Description

Fortress Power Envy Duo 21 48V Hybrid Solar Inverter – 16kW High-Power Output for Home & Small Business

The Envy Duo 21 is Fortress Power’s most powerful 48V hybrid inverter, built to handle both residential and light commercial energy needs. With up to 25kW solar input and dual-phase support (240V split-phase and 208V three-phase), it delivers a reliable 12kW of continuous backup power with up to 16kW export capacity.

Perfectly paired with Fortress Power’s 48V batteries, the Envy Duo 21 offers flexible applications from whole-home backup to off-grid living. With built-in AC/DC breakers, rapid shutdown transmitter, and scalability up to 120kW, it’s a future-ready solution designed for maximum performance and long-term reliability.

📄 View Data Sheet (PDF)

Envy Duo 21 Installation Manual

Envy Duo 21 Data Sheet

Envy Duo 21 Warranty

PV Output Data
Number of MPPT 3
Inputs per MPPT 2:2:1
Max. usable input current (A) 26/26/15
Max. short circuit input current (A) 31/31/19
Start input voltage (V) 100
MPPT DC nominal voltage (V) 360
DC voltage range (V) 100-550
MPPt operating voltage range (V) 120-440
Max. Power (W) 21000
Max. PV ARRAY POWER (W) 25000
Backup Output Data
Nominal output current (A) 50@240V, 57.7@208V
Nominal output voltage (V) (120/240), (120/208)
Continuous output power (VA) 12000@240V, 12000@208V
Operating frequency (Hz) 60 & 50
Peak power (VA) 2xPn, 0.5s
THDV <3%
Switching Time (ms) <20
General Data
Paralleling Capabiliy Up to 10 units (120kW)
Dimensions 22.3 x 35.2 x 11.2 in (566 x 893 x 285 mm)
Weight 125.71 lbs (57 kg)
Degree of protection NEMA4X / IP66
Cooling concept Smart Cooling Fans
Topology High Frequency Transformer-less
Relative humidity 0-100%
Altitude (m) <6561ft. (<2000m)
Operating Temperature Range (ºC) -25~60>40 Derating
Noise emission (dB) <67
Idle Consumption AVG (W) 60
Display Touch color screen
Communication interface Rs485/ Wi-Fi/ CAN
AC Grid Output Data
Max. Output Current with pv (A) 66.7
Max. Output Power with pv (W) 16000@240V 13800@208V
Continuous power output with battery only (W) 12000@240V, 12000@208V
Rated voltage (V) 120/240, 120/208
Operating voltage range (V) 180-270
Operating frequency (Hz) 50/60
Operating frequency range (Hz) 55-65
Power Factor 0.99@full load
Reactive power adjust range -0.8~+0.8 leadingAdjustable
THDI <3%
Sync inrush current (A) 35
Efficiency
Max. EFFICIENCY PV to grid 97.50%
Max. EFFICIENCY battery to grid 94%
CEC Efficiency 96.90%
Battery Data
Type Lithium battery/ No Battery
Max. charge current (A) 250
Max. discharge current (A) 250
Nominal voltage (V) 48
Voltage range (V) 40-60

Frequently Asked Questions

Yes! We provide free and fast shipping on MOST orders within the continental United States. However, some specific brands and items will require a quote. You can live chat or call us for a quote
Most orders ship out within 1–2 business days and arrive within 3–5 business days depending on your location.
We offer easy returns as long as your item meets the conditions outlined in our Return Policy. Items must be unused, in original packaging, and returned within the specified return window.
Absolutely! Our in-house product experts are here to help. Live chat or call us 513-743-829 for personalized advice before or after your purchase.
Yes. All products include any applicable manufacturer warranties, and we’ll help you handle any warranty claims if needed.
Yes, we only sell 100% authentic, brand-new products, sourced directly from our manufacturers or authorized distributors.
REAL REVIEWS, REAL RESULTS

Feedback From Our Customers

At Green Vista Living, we pride ourselves on delivering top-quality products and exceptional service to solar professionals and homeowners alike. Here's what our customers have to say about their experiences with us.

Kevin Leary
May 18, 2025
★★★★★

Incredible Tech Support from Anees of Green Vista Living. Exceptional service and went above and beyond on every question.

Bryan Cunningham
Off grid Kit • Dec 21, 2025
★★★★★

Shipment was slow due to high demand, but the team kept me informed and ensured everything arrived properly.

Related Products