Envy Duo 21G Inverter
A high-capacity hybrid inverter with full-system monitoring engineered for larger solar + storage systems.
Envy Duo 21G Inverter
Maximum Power. Complete System Visibility.
The Fortress Power Envy Duo 21G is a powerful 48V hybrid inverter built for demanding residential and light commercial energy needs. It includes the Guardian Wi-Fi dongle and adds a dedicated communication board inside the inverter. Together they let installers and homeowners see both the inverter and the battery in the Fortress Power Pro and Owner mobile apps and the web portal, with no external Guardian device required. With a maximum PV input of 25kW and dual-phase compatibility (240V split-phase and 208V three-phase), it delivers 12kW of continuous backup output and up to 16kW of export power. Integrated AC/DC breakers, a rapid shutdown transmitter, and parallel scalability up to 120kW make it a connected, future-ready solution.
Perfectly matched with Fortress Power’s 48V battery systems, the Envy Duo 21 supports multiple applications.
Applications
Residential
Light Commercial
FEATURES
* Minimum of three or more inverters in parallel is needed.
About the included Guardian Wi-Fi Dongle
Every Envy Duo 21G ships with the Guardian Wi-Fi Dongle, the latest communication device for Fortress Power systems and the replacement for the previous Guardian Gateway. It plugs directly into the inverter’s communication port, so there’s no separate Guardian device to buy, mount, or wire.
Paired with the 21G’s built-in communication board, the dongle brings your inverter and Fortress Power battery into one view in the Pro and Owner apps and the web portal.
Key benefits include:
- Included with every Envy Duo 21G, no extra hardware to purchase
- Plugs directly into the inverter for a simple, clean installation
- Inverter and battery monitoring together with any Fortress Power battery
- Secure cloud-based monitoring, remote support, and firmware updates
- Works with the Fortress Power Pro and Owner mobile apps
Installers can commission the system and connect the dongle in the Pro app. Homeowners can then monitor and manage their system in the Owner app. For help with setup, contact your installer or Fortress Power Technical Support.
PRODUCT INFORMATION
| 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 |
VIDEO LIBRARY
Envy Duo 21 Video Library
0:35
1:09:05
6:47
10:25
8:14
ENVY MOBILE APP FEATURES
PRODUCT COMPATIBILITY
FREEDOM OF CHOICE WITH OUR ENVY INVERTERS!
Our Envy inverters are battery-agnostic!
What does this mean for you? It means you get to choose the battery that aligns with your vision. Our inverters seamlessly integrate with a wide range of lithium batteries. We have compiled a list of all the battery manufacturers you can choose from!
Info Sheet
Download Here
Two Apps. One Powerful Energy Ecosystem.
The Fortress Power Owner and Pro apps give homeowners and installers the right tools to monitor, manage, and support Fortress Power systems, anytime, anywhere.