Illustration · 120 half-cut cells

Solar panelSuntech

Suntech STP330S-A21/Wfhb

Name: Suntech STP330S-A21/Wfhb
Brand: Suntech

120 half-cut cells. Power classes 310–350 W in the CEC list.

CEC listed · Oct 12, 2020UL 61730

Power class

Power (STC)330 WCEC nameplate
Efficiency≈19.1%calculated from area
%/°C Pmax−0.341CEC listing test
PTC / STC93.1%PTC 307 W (CEC)

Power classes

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation · 9 models

Model	Pmax	Voc, V	Isc, A	Vmp, V	Imp, A	Efficiency	PTC	CEC listed
STP310S-A21/Wfhb	310 W	41.30	9.46	35.00	8.86	≈17.9%	288 W	Oct 12, 2020
STP315S-A21/Wfhb	315 W	41.50	9.55	35.20	8.95	≈18.2%	293 W	Oct 12, 2020
STP320S-A21/Wfhb	320 W	41.70	9.64	35.40	9.04	≈18.5%	298 W	Oct 12, 2020
STP325S-A21/Wfhb	325 W	41.90	9.73	35.60	9.13	≈18.8%	303 W	Oct 12, 2020
STP330S-A21/Wfhb	330 W	42.10	9.82	35.80	9.22	≈19.1%	307 W	Oct 12, 2020
STP335S-A21/Wfhb	335 W	42.30	9.91	36.00	9.31	≈19.4%	312 W	Oct 12, 2020
STP340S-A21/Wfhb	340 W	42.50	10.00	36.20	9.40	≈19.7%	317 W	Oct 12, 2020
STP345S-A21/Wfhb	345 W	42.70	10.08	36.40	9.48	≈19.9%	322 W	Oct 12, 2020
STP350S-A21/Wfhb	350 W	42.90	10.17	36.60	9.57	≈20.2%	326 W	Oct 12, 2020

≈ efficiency = Pmax ÷ CEC-listed area 1.73 m².

Build & dimensions

CEC PV Module List (Oct 7, 2026)

Module area1.73 m² (18.6 ft²)CEC-listed area
Cells120 half-cut cells
Back coverBlack backsheet

Heat & cold behaviour

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation

	CEC listing test
Pmax coefficient γ	−0.341 %/°C
Voc coefficient β	−0.267 %/°C
Isc coefficient α	+0.054 %/°C
Operating cell temperature	NOCT 45.5 °C

Vmp coefficient ≈ γ − α (CEC); used only for the hot-roof voltage estimate.

Away from lab conditions — CEC listing test points

Class	Pmax at NOCT	Vmp × Imp at NOCT	Pmax at 200 W/m²	Low-light efficiency vs STC
310 W	232.4 W	32.39 V × 7.18 A	60.3 W	97%
315 W	236.1 W	32.57 V × 7.25 A	61.3 W	97%
320 W	239.9 W	32.76 V × 7.32 A	62.3 W	97%
325 W	243.6 W	32.94 V × 7.4 A	63.2 W	97%
330 W	247.4 W	33.13 V × 7.47 A	64.2 W	97%
335 W	251.2 W	33.31 V × 7.54 A	65.2 W	97%
340 W	255.1 W	33.5 V × 7.61 A	66.2 W	97%
345 W	258.7 W	33.68 V × 7.68 A	67.1 W	97%
350 W	262.6 W	33.87 V × 7.75 A	68.2 W	97%

Pmax = Vmp × Imp from the CEC listing; low-light efficiency = Pmax at 200 W/m² ÷ (20% of STC Pmax).

Independent reliability testing

Kiwa PVEL Scorecard

PVEL Scorecards

Suntech named Top Performer, 2014–2024

This exact series is not listed in published PVEL Top Performer tables. Results below are for the manufacturer.

Inverter compatibility & string sizing

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation · NLR PVWatts v8 · inverter datasheets · NLR SAM inverter library · CEC Grid Support Inverter List (Oct 7, 2026)

CityColdest air, °CHottest cell, °CString inverter

44.7 V

Voc when cold

per panel

28.9 V

Vmp when hot

per panel

Max panels / string

max DC 600 V

Min panels / string

MPPT from 60 V

Defaults come from NLR TMY weather (coldest hour, hottest modeled cell). Code calculations (NEC 690.7) use the ASHRAE extreme annual minimum, which is usually colder — enter it above. β is the CEC-measured coefficient; NEC 690.7 calculations use the datasheet value.

String inverters most named in SoCal permits

Inverter	Max DC input	MPPT	Window source	Panels per string
Tesla 1538000-xx-y	600 V	60–480 V	datasheet	3–13
Solis (Ginlong) S6-EH1P10K-H-US	600 V	80–520 V	datasheet	3–13
Solis (Ginlong) Solis-1P7.6K-4G-US	600 V	100–500 V	datasheet	4–13
Qcells Q.VOLT H7.6SX	498 V	234–498 V	CEC test window	9–11

Microinverters (one per panel)

Microinverter	Recommended module power	Max DC input	MPPT	Voc cold / Vmp hot	Check	DC/AC
Enphase IQ8PLUS-72-2-US	235–440 W	60 V	29–45 V	44.7 / 28.9 V	⚠ Works; below MPPT at peak heat	1.14
Enphase IQ8X-80-M-US	320–540 W	79.5 V	43–60 V	44.7 / 28.9 V	✗ Not a match: module voltage below MPPT range	0.87
APsystems (Alt Power System) DS3-L	265–570 W	60 V	28–45 V	44.7 / 28.9 V	✓ Within range	0.42
Enphase IQ8M-72-2-US	260–460 W	60 V	30–45 V	44.7 / 28.9 V	⚠ Works; below MPPT at peak heat	1.02
Enphase IQ8A-72-2-US	295–500 W	60 V	32–45 V	44.7 / 28.9 V	⚠ Works; below MPPT at peak heat	0.95

Voltage check against the microinverter datasheets — confirm the pairing on the manufacturer’s module compatibility list. Rows appear only when the panel’s power is inside the microinverter’s recommended module power range.

SolarEdge and other optimizer-based systems size strings by the optimizer rules — use the manufacturer’s designer. Reference inverters: most named in SoCal permits since Oct 2024.

Expected production in Southern California

NLR PVWatts v8 · Cali-Graf calculation

PanelsCity for chartSystem size

City	kWh / kW / yr	kWh / panel / yr	kWh / system / yr	Sun, kWh/m²/day
Los Angeles	1,676	553	11,615	6.08
Palmdale	1,835	606	12,717	6.69
Chula Vista	1,696	560	11,753	6.11
Huntington Beach	1,643	542	11,386	5.89
Riverside	1,696	560	11,753	6.21
Santa Clarita	1,724	569	11,947	6.28

Estimate for comparison, not a quote: shading, roof orientation and local losses change real output. Roof mount, 20° tilt, south, 14% system losses.

Compare with similar 330 W panels

CEC PV Module List (Oct 7, 2026) · Kiwa PVEL Scorecard · datasheets · building permits

Panel	Pmax	Efficiency	γ Pmax (CEC)	Voc, V	Isc, A	PVEL (product / brand)	SoCal permits (series)
Suntech STP330S-A21/Wfhb	330 W	≈19.1%	−0.341	42.1	9.82	brand 6×	—
LONGi LR4-60HPB-335M	335 W	≈18.5%	−0.337	39.9	10.76	product 2021, 2022	193
JinkoSolar JKM330M-60HBL	330 W	≈19.6%	−0.406	40.6	10.61	brand 12× (2014–2026)	45
Qcells Q.PEAK DUO-G8+ 330	330 W	≈18.4%	−0.343	39.71	10.52	product 2022	20

Same fields from the same sources for every row; ≈ efficiency is calculated from the listed area. Comparable series: other brands, same product group, power range covering this class.

Questions & answers

How efficient is the Suntech STP330S-A21/Wfhb?

Calculated from the panel area (1.73 m²): about 19.1% for the 330 W class. 330 W over 1.73 m² equals about 191 W per square meter.

How much energy does one panel produce in Los Angeles or Palmdale?

PVWatts v8 with typical-year weather gives about 553 kWh per year per 330 W panel in Los Angeles and about 606 kWh in Palmdale (20° roof, facing south, 14% system losses).

How much power does it lose on a hot roof?

With γ = −0.341 %/°C, at a 77 °C cell temperature (hottest modeled hour in Palmdale) output is about 17.7% below the STC rating.

How many panels fit on one string?

With the Tesla 1538000-xx-y (max DC 600 V, MPPT from 60 V, datasheet) in Los Angeles the calculator gives 3–13 panels per string (Voc at 2 °C = 44.7 V, Vmp at 74 °C cell = 28.9 V). Final design must follow the inverter manual and NEC 690.7.

Does it work with APsystems (Alt Power System) DS3-L microinverters?

Voltage check against the APsystems (Alt Power System) datasheet: Voc when cold 44.7 V vs max input 60 V; Vmp when hot 28.9 V vs MPPT low 28 V; recommended module power 265–570 W. Confirm on the microinverter maker’s compatibility list.

Has this panel been reliability-tested?

This exact series is not in published PVEL Top Performer tables; Suntech was named a Top Performer in 6 Scorecards (2014–2024).

Sources

California Energy Commission — Solar Equipment Lists, PV Module List, Inverter List (snapshot Oct 7, 2026).
JinkoSolar — datasheet THE MOST DEPENDABLE SOLAR BRAND.
JinkoSolar — manufacturer datasheet “Eagle HC 60M G2 315-335 Watt MONO PERC HALF CELL MODULE”.
Qcells — manufacturer datasheet “Q.PEAK DUO-G8+ 345-360 EN ENDURING HIGH”.
Kiwa PVEL — PV Module Reliability Scorecard, Top Performer lists 2014–2024.
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, Chula Vista, Huntington Beach, Riverside, Santa Clarita.
Inverter datasheets — APsystems (Alt Power System), Enphase, Solis (Ginlong), Tesla (manufacturer documents).
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).