Solar Frontier SFK185-S

Name: Solar Frontier SFK185-S
Brand: Solar Frontier

184 cells. Power classes 180–190 W in the CEC list.

CEC listed · Jan 21, 2020UL 61730, UL 1703

Power class

Power (STC)185 WCEC nameplate
Efficiency≈15.7%calculated from area
%/°C Pmax−0.352CEC listing test
PTC / STC92.4%PTC 171 W (CEC)

Power classes

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation · 3 models

Model	Pmax	Voc, V	Isc, A	Vmp, V	Imp, A	Efficiency	PTC	CEC listed
SFK180-S	180 W	120.00	2.18	92.40	1.95	≈15.3%	166 W	Jan 21, 2020
SFK185-S	185 W	121.00	2.19	95.00	1.95	≈15.7%	171 W	Jan 21, 2020
SFK190-S	190 W	122.00	2.21	97.10	1.96	≈16.1%	176 W	Mar 1, 2021

≈ efficiency = Pmax ÷ CEC-listed area 1.18 m².

Build & dimensions

CEC PV Module List (Oct 7, 2026)

Module area1.18 m² (12.7 ft²)CEC-listed area
Cells184 cells
Back coverBlack backsheet

Heat & cold behaviour

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

	CEC listing test
Pmax coefficient γ	−0.352 %/°C
Voc coefficient β	−0.261 %/°C
Isc coefficient α	+0.005 %/°C
Operating cell temperature	NOCT 45.8 °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
180 W	132.1 W	86.15 V × 1.53 A	33.4 W	93%
185 W	135.8 W	88.57 V × 1.53 A	34.3 W	93%
190 W	139.5 W	90.53 V × 1.54 A	35.2 W	93%

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

Inverter compatibility & string sizing

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation · NLR PVWatts v8

CityColdest air, °CHottest cell, °C

128.3 V

Voc when cold

per panel

78.4 V

Vmp when hot

per panel

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.

Microinverter tables are not shown for panels under 200 W.

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	310	9,302	6.08
Palmdale	1,835	339	10,184	6.69
Chula Vista	1,696	314	9,413	6.11
Huntington Beach	1,643	304	9,119	5.89
Riverside	1,696	314	9,413	6.21
Santa Clarita	1,724	319	9,568	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.

Questions & answers

How efficient is the Solar Frontier SFK185-S?

Calculated from the panel area (1.18 m²): about 15.7% for the 185 W class. 185 W over 1.18 m² equals about 157 W per square meter.

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

PVWatts v8 with typical-year weather gives about 310 kWh per year per 185 W panel in Los Angeles and about 339 kWh in Palmdale (20° roof, facing south, 14% system losses).

How much power does it lose on a hot roof?

With γ = −0.352 %/°C, at a 77 °C cell temperature (hottest modeled hour in Palmdale) output is about 18.2% below the STC rating.

Sources

California Energy Commission — Solar Equipment Lists, PV Module List (snapshot Oct 7, 2026).
NLR (formerly NREL) — PVWatts v8, NSRDB PSM v3 typical-year weather for Los Angeles, Palmdale, Chula Vista, Huntington Beach, Riverside, Santa Clarita.
Cali-Graf calculations — formulas and inputs are shown next to each calculated value (efficiency from area, temperature-corrected voltages, string sizing, energy estimates).