SMA STP 25-US-50

Name: SMA STP 25-US-50
Brand: SMA

String inverter. 4 models, 13 kW–30 kW AC at 208 V / 480 V.

UL 1741 SBCEC listed · Sep 1, 2023

Model

Rated AC power25 kW
CEC weighted efficiency98.0%

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
STP 13-US-50	13 kW	208 V	13 kW	13 kW	97.0%	230–640 V	Sep 11, 2025	SB
STP 20-US-50	20 kW	480 V	20 kW	20 kW	97.5%	350–800 V	Sep 1, 2023	SB
STP 25-US-50	25 kW	480 V	25 kW	25 kW	98.0%	430–800 V	Sep 1, 2023	SB
STP 30-US-50	30 kW	480 V	30 kW	30 kW	98.0%	515–800 V	Sep 1, 2023	SB

DC input (PV side)

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

CEC test DC voltages (min / nom / max)430 / 708 / 800 V
DC input at rated output (CEC test)25.5 kW

Efficiency

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

CEC weighted efficiency98.0%
Night-time standby (tare)4.7 W
Power to start converting74 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 — UL, certificate Aug 6, 2025
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) conformanceVia gateway during testing (Y*)
Monitor key data & scheduling (Rule 21 Phase 3)No
CEC listedSep 1, 2023
Last CEC updateNov 1, 2023

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

STP 25-US-50: max DC 800 V · MPPT 430–800 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	15–16	—
Qcells Q.PEAK DUO BLK ML-G10+ 410	410 W	48.1 V	30.6 V	15–16	—
LONGi LR5-54HABB-400M	400 W	39.3 V	25.3 V	17–20	—
JA Solar JAM54S31-405/MR	405 W	39.4 V	25.5 V	17–20	—
Hyundai Solutions HiN-T440NF(BK)	440 W	40.9 V	27 V	16–19	—
Silfab Solar SIL-440QD	440 W	41.1 V	28 V	16–19	—
Qcells Q.TRON BLK M-G2+ 430	430 W	41.3 V	28 V	16–19	—
Qcells Q.TRON BLK M-G2.H+ 430	430 W	41.3 V	28 V	16–19	—
REC Group REC460AA Pure-RX	460 W	68.8 V	47.1 V	10–11	—
Elin (Sirius PV) ELNSM54M-HC-410	410 W	39.3 V	25.3 V	17–20	—
Qcells Q.TRON BLK M-G2.C+ 430	430 W	41.3 V	28 V	16–19	—
Tesla TSP-420	420 W	43.4 V	27.7 V	16–18	—

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 25 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
SMA STP xx-US-50	13 kW–30 kW	98.0%	430–800 V	Yes	2025	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-R/US-480	20 kW–25 kW	98.0%	560–850 V	Yes	2020	1
SMA STP xx-US-80	27.5 kW–70 kW	97.5%	300–850 V	Yes	2026	—
Canadian Solar CSI-xxK-T480GL03-U	25 kW–100 kW	98.5%	550–850 V	Yes	2024	—

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

About SMA

CEC Grid Support Inverter List (Oct 7, 2026)

ManufacturerSMA
Listed in CEC asSMA America
Websitesma-america.com
Models on CEC lists202

Other series

STP xx-US-80SHP FLEX-US-21SHP xxx-US-21

Questions & answers

How efficient is the SMA STP xx-US-50?

The California Energy Commission lists a weighted efficiency of 97.0–98.0% for SMA STP xx-US-50 models, measured at six power levels and three DC voltages.

What sizes does the SMA STP xx-US-50 come in?

The CEC list includes 4 models from 13 kW to 30 kW AC: STP 13-US-50, STP 20-US-50, STP 25-US-50, STP 30-US-50.

Is the SMA STP xx-US-50 certified to UL 1741 SB?

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

What is the STP 25-US-50’s DC input voltage range?

CEC tested it at 430–800 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).