Illustration

Hybrid inverterFortress Power

Fortress Power FP-Nano-50k-N

Name: Fortress Power FP-Nano-50k-N
Brand: Fortress Power

Hybrid inverter, dc-coupled hybrid (pv + battery). 4 models, 29.9 kW–59.8 kW AC at 480 V.

UL 1741 SBCEC listed · Apr 21, 2026

Model

Rated AC power49.8 kW
CEC weighted efficiency97.5%

Models & power ratings

CEC Grid Support Inverter List (Oct 7, 2026) · NLR SAM inverter library · 4 models

Model	Nominal AC	Grid voltage	CEC continuous	Rated AC (SAM)	CEC weighted eff.	DC test window	CEC listed	UL 1741 SB
FP-Nano-30k-N	29.9 kW	480 V	29.9 kW	29.9 kW	97.0%	500–850 V	Apr 21, 2026	SB
FP-Nano-40k-N	39.8 kW	480 V	39.8 kW	39.8 kW	97.0%	500–850 V	Apr 21, 2026	SB
FP-Nano-50k-N	49.8 kW	480 V	49.8 kW	49.8 kW	97.5%	600–850 V	Apr 21, 2026	SB
FP-Nano-60k-N	59.8 kW	480 V	59.8 kW	59.8 kW	97.5%	600–850 V	Apr 21, 2026	SB

Some models are also on the CEC Battery Inverter list — one product, two listings.

DC input (PV side)

CEC Grid Support Inverter List (Oct 7, 2026) · NLR SAM inverter library

CEC test DC voltages (min / nom / max)600 / 725 / 850 V
DC input at rated output (CEC test)51.1 kW

Efficiency

CEC Grid Support Inverter List (Oct 7, 2026) · NLR SAM inverter library

CEC weighted efficiency97.5%
Night-time standby (tare)76 W
Power to start converting208.6 W

CEC weighted efficiency is measured by an accredited lab at six power levels and three DC voltages — the number to compare between inverters.

Grid & smart-inverter certification

CEC Grid Support Inverter List (Oct 7, 2026)

UL 1741 SB (3rd ed.)Yes — TUV Rheinland of North America, certificate Feb 11, 2026
UL 1741 SA (SA8–SA13)No
Volt-VAr with reactive power priority (SA13)No
Freq-Watt / Volt-Watt (SA14–15)No
Disable permit service / limit active power (SA17–18)No
CSIP (IEEE 2030.5) conformanceYes — TÜV Rheinland, Dec 29, 2025
Anti-islanding method groupsGroups 1, 2a, 2b, 2c, 3, 4, 5, 6 (manufacturer-reported)
Power control system (PCS)Stated in CEC listing (power control system)
Built-in meterYes
CEC listedApr 21, 2026
Last CEC updateMay 21, 2026

UL 1741 SB is required for new interconnections in California (Rule 21) since 2026.

Monitoring & communication

CEC Grid Support Inverter List (Oct 7, 2026)

Built-in production meterBuilt-in meter (CEC listing)

Panel compatibility & string sizing

NLR SAM inverter library · NLR PVWatts v8 · CEC PV Module List · Cali-Graf calculation

CityColdest air, °CHottest cell, °C

FP-Nano-50k-N: max DC 850 V · MPPT 600–850 V (CEC test window)

Most-permitted panels in Southern California

Panel	Power	Voc cold	Vmp hot	Panels per string	Installed together
Qcells Q.PEAK DUO BLK ML-G10.C+ 410	410 W	48.1 V	30.6 V	no fit	—
Qcells Q.PEAK DUO BLK ML-G10+ 410	410 W	48.1 V	30.6 V	no fit	—
LONGi LR5-54HABB-400M	400 W	39.3 V	25.3 V	no fit	—
JA Solar JAM54S31-405/MR	405 W	39.4 V	25.5 V	no fit	—
Hyundai Solutions HiN-T440NF(BK)	440 W	40.9 V	27 V	no fit	—
Silfab Solar SIL-440QD	440 W	41.1 V	28 V	no fit	—
Qcells Q.TRON BLK M-G2+ 430	430 W	41.3 V	28 V	no fit	—
Qcells Q.TRON BLK M-G2.H+ 430	430 W	41.3 V	28 V	no fit	—
REC Group REC460AA Pure-RX	460 W	68.8 V	47.1 V	no fit	—
Elin (Sirius PV) ELNSM54M-HC-410	410 W	39.3 V	25.3 V	no fit	—
Qcells Q.TRON BLK M-G2.C+ 430	430 W	41.3 V	28 V	no fit	—
Tesla TSP-420	420 W	43.4 V	27.7 V	no fit	—

Voltage check only, from CEC panel data and NLR weather for the city. Final design must follow the inverter manual and NEC 690.7.

Compare with similar 49.8 kW inverters

CEC Grid Support Inverter List (Oct 7, 2026) · building permits

Inverter	Power	CEC weighted eff.	DC test window	UL 1741 SB	Latest CEC	SoCal permits
Fortress Power FP-Nano-xxk-N	29.9 kW–59.8 kW	97.5%	600–850 V	Yes	2026	0
Solis (Ginlong Technologies) S6-EH3PxxK04-NV-YD-H-US(21A)	39.8 kW–59.8 kW	97.5%	500–850 V	Yes	2026	—
Solis (Ginlong Technologies) S6-EH3PxxK04-NV-YD-H-US	40 kW–60 kW	97.5%	360–850 V	Yes	2025	—
Growatt WIT xxK-H-US	50 kW–100 kW	96.5%	520–800 V	Yes	2024	—
Growatt WIT xxK-HU-US	50 kW–100 kW	96.5%	520–800 V	Yes	2024	—

Same type and grid voltage, power range covering this model; same fields from the same sources.

About Fortress Power

CEC Grid Support Inverter List (Oct 7, 2026)

ManufacturerFortress Power
Listed in CEC asFortress Power LLC
Websitefortresspower.com
Models on CEC lists554

Other series

EdgeOn Duo 12EdgeOn Duo 12 LiteEdgeOn Duo 15EdgeOn Duo 15 LiteEdgeOn Duo 15 ProEdgeOn Duo 7.5EdgeOn Duo 9FP-Nano-30k-LFP-ENVY-xxKFP-Envy Duo 21

Questions & answers

How efficient is the Fortress Power FP-Nano-xxk-N?

The California Energy Commission lists a weighted efficiency of 97.0–97.5% for Fortress Power FP-Nano-xxk-N models, measured at six power levels and three DC voltages.

What sizes does the Fortress Power FP-Nano-xxk-N come in?

The CEC list includes 4 models from 29.9 kW to 59.8 kW AC: FP-Nano-30k-N, FP-Nano-40k-N, FP-Nano-50k-N, FP-Nano-60k-N.

Is the Fortress Power FP-Nano-xxk-N certified to UL 1741 SB?

Yes — the CEC Grid Support Inverter List shows UL 1741 SB for all models.

Can the Fortress Power FP-Nano-xxk-N be used with a battery?

The CEC lists it as a dc-coupled hybrid (pv + battery).

What is the FP-Nano-50k-N’s DC input voltage range?

CEC tested it at 600–850 V DC.

Sources

California Energy Commission — Grid Support Inverter List (solar and battery inverters), data as of Oct 7, 2026. Manufacturer-reported, confirmed by CEC against certificates and test reports.
NLR (formerly NREL) — System Advisor Model CEC inverter library (version 2026.7.3).
NLR (formerly NREL) — PVWatts v8, NSRDB PSM v3 typical-year weather for Los Angeles, Palmdale, Riverside, Santa Clarita, Chula Vista, Huntington Beach.
California Energy Commission — PV Module List (module electrical data for the compatibility check).
Building permits — Southern California permit portals. Equipment matched from permit descriptions.
Cali-Graf calculations — formulas and inputs are shown next to each calculated value (efficiency from area, temperature-corrected voltages, string sizing, energy estimates).