Northern Electric & Power Neptune40K

Name: Northern Electric & Power Neptune40K
Brand: Northern Electric & Power

String inverter. 9 models, 25 kW–100 kW AC at 480 V.

UL 1741 SBCEC listed · Feb 12, 2024

Model

Rated AC power40 kW
CEC weighted efficiency98.5%

Models & power ratings

CEC Grid Support Inverter List (Oct 7, 2026) · NLR SAM inverter library · 9 models

Model	Nominal AC	Grid voltage	CEC continuous	Rated AC (SAM)	CEC weighted eff.	DC test window	CEC listed	UL 1741 SB
Neptune25K	25 kW	480 V	24.9 kW	24.9 kW	98.5%	580–850 V	Feb 12, 2024	SB
Neptune30K	30 kW	480 V	29.9 kW	29.9 kW	98.5%	580–850 V	Feb 12, 2024	SB
Neptune33K	33 kW	480 V	32.9 kW	32.9 kW	98.5%	580–850 V	Feb 12, 2024	SB
Neptune36K	36 kW	480 V	35.9 kW	35.9 kW	98.5%	580–850 V	Feb 12, 2024	SB
Neptune40K	40 kW	480 V	39.8 kW	39.8 kW	98.5%	580–850 V	Feb 12, 2024	SB
Neptune50K	50 kW	480 V	49.8 kW	49.8 kW	98.5%	580–850 V	Feb 12, 2024	SB
Neptune60K	60 kW	480 V	59.9 kW	59.9 kW	98.5%	580–850 V	Feb 12, 2024	SB
Neptune75K	75 kW	480 V	74.6 kW	74.6 kW	98.5%	550–850 V	Mar 1, 2024	SB
Neptune100K	100 kW	480 V	99.4 kW	99.4 kW	98.0%	550–850 V	Mar 1, 2024	SB

DC input (PV side)

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

CEC test DC voltages (min / nom / max)580 / 720 / 850 V
DC input at rated output (CEC test)40.6 kW

Efficiency

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

CEC weighted efficiency98.5%
Night-time standby (tare)3.27 W
Power to start converting107.8 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 — CSA Group, certificate Oct 31, 2023
UL 1741 SA (SA8–SA13)Yes — CSA Group
Firmware tested (SA)A2, 1C
Volt-VAr with reactive power priority (SA13)Yes
Freq-Watt / Volt-Watt (SA14–15)Yes
Disable permit service / limit active power (SA17–18)Yes
CSIP (IEEE 2030.5) conformanceVia gateway during testing (Y*)
Monitor key data & scheduling (Rule 21 Phase 3)Yes (attested Mar 1, 2024)
CEC listedFeb 12, 2024

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

Panel compatibility & string sizing

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

CityColdest air, °CHottest cell, °C

Neptune40K: max DC 850 V · MPPT 580–850 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 40 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
Northern Electric & Power NeptunexxK	25 kW–100 kW	98.5%	580–850 V	Yes	2024	0
SolarEdge SExKUS	9 kW–330 kW	99.0%	100–1,400 V	16 of 19	2025	14
CPS (Chint Power Systems) CPS SCAxxKTL-DO/US-480	36 kW–60 kW	98.5%	400–850 V	Yes	2023	3
SMA STP xx-US-80	27.5 kW–70 kW	97.5%	300–850 V	Yes	2026	—
Yaskawa Solectria Solar PVI xxTL-480	36 kW–100 kW	98.5%	340–850 V	3 of 4	2025	—

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

About Northern Electric & Power

CEC Grid Support Inverter List (Oct 7, 2026)

ManufacturerNorthern Electric & Power
Listed in CEC asNorthern Electric & Power Co. Ltd
Models on CEC lists49

Other series

NeptunexxK-LV

Questions & answers

How efficient is the Northern Electric & Power NeptunexxK?

The California Energy Commission lists a weighted efficiency of 98.0–98.5% for Northern Electric & Power NeptunexxK models, measured at six power levels and three DC voltages.

What sizes does the Northern Electric & Power NeptunexxK come in?

The CEC list includes 9 models from 25 kW to 100 kW AC: Neptune25K, Neptune30K, Neptune33K, Neptune36K, Neptune40K, Neptune50K, Neptune60K, Neptune75K….

Is the Northern Electric & Power NeptunexxK certified to UL 1741 SB?

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

What is the Neptune40K’s DC input voltage range?

CEC tested it at 580–850 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).