Envy Duo 21 vs. Envy Duo 21-G: What’s the Difference?
At first glance, the Envy Duo 21 and Envy Duo 21-G share the same foundation. Both are powerful hybrid inverters designed to deliver reliable backup power, intelligent energy management, and seamless integration with Fortress Power battery storage solutions.
The difference lies in the details.
The Envy Duo 21-G builds on the proven performance of the Envy Duo 21 with increased solar capacity, higher AC output, enhanced backup performance at 208V, and an upgraded monitoring experience. Whether you’re designing a residential system with a larger PV array or a light commercial installation with higher energy demands, understanding these differences can help you select the right inverter for the job. Let’s take a closer look.
More Solar Capacity for Greater Design Flexibility
One of the biggest upgrades in the Envy Duo 21-G is its expanded PV capability. While both models support up to 25 kW of PV input, the Envy Duo 21-G increases usable PV power from 18 kW to 21 kW and supports up to five PV strings, compared to four on the Envy Duo 21.
For installers, that means greater flexibility when designing systems with larger arrays or more complex roof layouts — without increasing system complexity.
| Feature | Envy Duo 21 | Envy Duo 21-G |
|---|---|---|
| Maximum PV Strings | 4 | 5 |
| Maximum PV Input | 25 kW | 25 kW |
| Usable PV Power | 18 kW | 21 kW |
Higher AC Output
The Envy Duo 21 delivers 12 kW of maximum AC output, making it an excellent solution for a wide range of residential applications.
For projects with larger loads or greater daytime energy demands, the Envy Duo 21-G increases maximum AC output to 16 kW, providing additional capacity without sacrificing the reliability installers expect from the Envy platform.
Full Backup Performance at Both 240V and 208V
Reliable backup power is at the core of every Envy Duo installation. Both models provide 12 kW of backup power at 240V, ensuring dependable operation during grid outages.
Where the Envy Duo 21-G stands out is at 208V. Instead of 10.4 kW, the Duo 21-G delivers the full 12 kW of backup power, making it an ideal choice for applications where 208V service is required.
| Backup Output | Envy Duo 21 | Envy Duo 21-G |
|---|---|---|
| 240V | 12 kW | 12 kW |
| 208V | 10.4 kW | 12 kW |
Enhanced Monitoring Experience
Both inverters provide remote monitoring and system visibility, but the Envy Duo 21-G introduces the new Fortress Power monitoring platform, offering an updated interface and enhanced system management capabilities.
This gives installers and homeowners improved visibility into system performance, easier diagnostics, and simplified remote monitoring.
Reliable Backup Power When It Matters Most
At the end of the day, customers aren’t buying batteries or inverters. They’re buying reliability. When paired together, Envy and eBoost help ensure essential loads remain powered during grid outages. Lights stay on, refrigerators continue running, internet connections remain active, and homeowners gain greater confidence in their energy security.
For installers, that means delivering a solution that not only performs on paper but also provides real-world value when outages occur.
Which Envy Duo Is Right for Your Project?
The Envy Duo 21 remains an outstanding choice for residential energy storage systems, offering dependable hybrid performance, seamless battery integration, and reliable backup power.
For projects requiring additional solar capacity, higher AC output, full 208V backup capability, or greater installation flexibility, the Envy Duo 21-G provides meaningful performance enhancements while maintaining the same trusted Fortress Power experience.
Whether you’re designing a residential backup system or a larger, more demanding installation, the Envy Duo family delivers the performance, reliability, and intelligent energy management needed to power today’s energy storage projects.