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Fortress Power Envy Duo 21 16kW Whole Home Solar Hybrid Inverter

Fortress Power Envy Duo 21 16kW Whole Home Solar Hybrid Inverter
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$5,398.00
$5,398.00 - $5,398.00
$5,398.00
$4,898.00
$4,898.00 - $4,898.00
$4,898.00
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16kW · 25kW Solar Input · Whole Home

Fortress Power Envy Duo 21 16kW Whole Home Solar Hybrid Inverter

The Envy Duo 21 delivers 12kW of continuous output, climbing to 16kW with solar assist, backed by up to 25kW of PV array input across three MPPT trackers — built for whole-home systems that need serious solar capacity.

It's configurable to run with or without a battery, outputs both 120/240V split-phase and 120/208V, and carries a NEMA 4X / IP66 rating for demanding outdoor installs.

Fortress Power Envy Duo 21 16kW Whole Home Solar Hybrid Inverter
10-Year Warranty
Lowest Price Guarantee
Authorized Fortress Power Dealer
Free Shipping
0% APR Financing
Expert Support: (303) 876-7654

Why the Envy Duo 21

16kW Output, 25kW of Solar Input

12kW continuous output climbs to 16kW with solar assist, backed by up to 25kW of PV array capacity across three MPPT trackers.

Dual-Phase Output

Delivers both 120/240V split-phase and 120/208V configurations from a single inverter.

NEMA 4X / IP66 Rated

A sealed enclosure rated for demanding outdoor installations.

Parallel Up to 10 Units, 120kW Total

Scale from a single inverter up to 120kW of combined AC output.

Battery-Optional Operation

Configurable to run with a lithium battery or without one, for grid-tied-only installations.

UL1741 and UL9540 Certified

Certified to the standards that matter for grid-interactive and energy storage installations.

What's Included

What's included with the Fortress Power Envy Duo 21

What You Get

  • 1 × Fortress Power Envy Duo 21 16kW Whole Home Solar Hybrid Inverter
  • Documentation

Battery bank and solar array sold separately.

Full Specifications

Model Fortress Power Envy Duo 21 (Envy Duo 21-US)
Continuous AC Output 12,000W @ 240V / 12,000W @ 208V
Max Output With Solar Assist 16,000W @ 240V / 13,800W @ 208V
Peak Output 2× rated power for 0.5 seconds
DC Input Voltage Range 100–550V
MPPT Operating Range 120–440V
Max PV Array Power 25,000W
MPPT Trackers 3 (2:2:1 input configuration)
Max Current Per MPPT 26A / 26A / 15A
Output Voltage Configuration 120/240V split-phase; 120/208V
Switching Time Under 20ms
Compatible Battery Types Lithium battery, or no battery (grid-tied configuration)
Nominal Battery Voltage 48V
Max Charge/Discharge Current 250A each
Efficiency PV-to-grid 97.5%; battery-to-grid 94%; CEC 96.9%
Parallel Capability Up to 10 units, up to 120kW combined
Dimensions 22.3"W × 35.2"H × 11.2"D
Weight 125.71 lb
Ingress Protection NEMA 4X / IP66
Certifications UL1741:2021 ED3, UL9540, UL3141, OGPE
Warranty 10 years (per Fortress Power's datasheet; full terms not listed on the product page itself)

Authorized Fortress Power Dealer

We sell genuine Fortress Power products backed by Fortress Power's own warranty.

Lowest Price Guarantee

Find it cheaper from another authorized dealer? Call (303) 876-7654 before you order.

Real Support, Not a Ticket Queue

Sizing a system or checking inverter compatibility? Call (303) 876-7654 and talk to a person.

Fortress Power Envy Duo 21 16kW Whole Home Solar Hybrid Inverter: Frequently Asked Questions

What do the "21" and "16kW" in the name actually refer to?
"21" is the maximum solar PV array input this inverter accepts (up to 25kW of array capacity), and "16kW" is the maximum output it can deliver at 240V with solar assist — 12kW is the continuous rating without that assist.
Do I need a battery to use this inverter?
No — it's configurable to run with a lithium battery or without one for a grid-tied-only setup. Call (303) 876-7654 if you want help deciding which configuration fits your goals.
Is this rated for outdoor installation?
Yes, it carries a NEMA 4X / IP66 rating, built for demanding outdoor conditions.
Can I add more inverters later?
Yes, up to 10 units can be paralleled for up to 120kW of combined AC output.
What's the warranty?
Fortress Power's datasheet lists a 10-year warranty, though the full terms aren't published on the product page itself. Call (303) 876-7654 and we'll get written confirmation of the exact terms before you order.
Can I install this myself, or do I need an electrician?
Fortress Power's equipment is designed for professional installation. We strongly recommend a licensed electrician or solar installer for any battery, inverter, or enclosure installation — call (303) 876-7654 if you need a referral in your area.
Do you offer financing or price matching?
Yes. We offer 0% APR financing options through Affirm at checkout, and our Lowest Price Guarantee applies — if you find this product cheaper at another authorized Fortress Power dealer, call us at (303) 876-7654 before you order and we'll take care of it.
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