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Illustration · 268 cells
Solar panelFirst Solar

First Solar FS-6445-P-B-2

268 cells. Power classes 420–470 W in the CEC list.

CEC listed · Dec 22, 2025UL 61730
Power class
  • Power (STC)445 WCEC nameplate
  • Efficiency≈17.7%calculated from area
  • %/°C Pmax−0.229CEC listing test
  • PTC / STC95%PTC 423 W (CEC)

Power classes

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation · 11 models
ModelPmaxVoc, VIsc, AVmp, VImp, AEfficiencyPTCCEC listed
FS-6420-P-B-2420 W224.162.65174.402.41≈16.7%398 WDec 22, 2025
FS-6425-P-B-2425 W224.832.66175.442.42≈16.9%403 WDec 22, 2025
FS-6430-P-B-2430 W225.482.66176.472.44≈17.1%408 WDec 22, 2025
FS-6435-P-B-2435 W226.142.67177.492.45≈17.3%413 WDec 22, 2025
FS-6440-P-B-2440 W226.782.68178.512.46≈17.5%418 WDec 22, 2025
FS-6445-P-B-2445 W227.422.69179.522.48≈17.7%423 WDec 22, 2025
FS-6450-P-B-2450 W228.062.69180.532.49≈17.9%427 WDec 22, 2025
FS-6455-P-B-2455 W228.692.70181.532.51≈18.1%432 WDec 22, 2025
FS-6460-P-B-2460 W229.312.71182.522.52≈18.3%437 WDec 22, 2025
FS-6465-P-B-2465 W229.932.72183.512.53≈18.5%442 WDec 22, 2025
FS-6470-P-B-2470 W230.552.72184.492.55≈18.7%447 WDec 22, 2025
≈ efficiency = Pmax ÷ CEC-listed area 2.52 m².

Heat & cold behaviour

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation
CEC listing test
Pmax coefficient γ−0.229 %/°C
Voc coefficient β−0.226 %/°C
Isc coefficient α+0.033 %/°C
Operating cell temperatureNOCT 46.8 °C
Vmp coefficient ≈ γ − α (CEC); used only for the hot-roof voltage estimate.

Away from lab conditions — CEC listing test points

ClassPmax at NOCTVmp × Imp at NOCTPmax at 200 W/m²Low-light efficiency vs STC
420 W317.3 W172.73 V × 1.84 A81.3 W97%
425 W321.1 W173.75 V × 1.85 A82.2 W97%
430 W324.9 W174.77 V × 1.86 A83.2 W97%
435 W328.7 W175.79 V × 1.87 A84.2 W97%
440 W332.5 W176.79 V × 1.88 A85.2 W97%
445 W336.3 W177.79 V × 1.89 A86.1 W97%
450 W340.1 W178.79 V × 1.9 A87.1 W97%
455 W343.9 W179.78 V × 1.91 A88.1 W97%
460 W347.5 W180.77 V × 1.92 A89 W97%
465 W351.4 W181.75 V × 1.93 A90 W97%
470 W355.2 W182.72 V × 1.94 A91 W97%
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
5
PVEL Scorecards
First Solar named Top Performer, 2018–2023
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)
239.3 V
Voc when cold
per panel
156.5 V
Vmp when hot
per panel
2
Max panels / string
max DC 600 V
1
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

InverterMax DC inputMPPTWindow sourcePanels per string
Tesla 1538000-xx-y600 V60–480 Vdatasheet1–2
Solis (Ginlong) S6-EH1P10K-H-US600 V80–520 Vdatasheet1–2
Solis (Ginlong) Solis-1P7.6K-4G-US600 V100–500 Vdatasheet1–2
Qcells Q.VOLT H7.6SX498 V234–498 VCEC test window2–2

Microinverters (one per panel)

MicroinverterRecommended module powerMax DC inputMPPTVoc cold / Vmp hotCheckDC/AC
Enphase IQ8X-80-M-US320–540 W79.5 V43–60 V239.3 / 156.5 V✗ Not allowed: cold Voc above max input1.17
APsystems (Alt Power System) DS3-L265–570 W60 V28–45 V239.3 / 156.5 V✗ Not allowed: cold Voc above max input0.57
Enphase IQ8M-72-2-US260–460 W60 V30–45 V239.3 / 156.5 V✗ Not allowed: cold Voc above max input1.37
Enphase IQ8A-72-2-US295–500 W60 V32–45 V239.3 / 156.5 V✗ Not allowed: cold Voc above max input1.28
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
CitykWh / kW / yrkWh / panel / yrkWh / system / yrSun, kWh/m²/day
Los Angeles1,67674611,9336.08
Palmdale1,83581713,0656.69
Chula Vista1,69675512,0766.11
Huntington Beach1,64373111,6985.89
Riverside1,69675512,0766.21
Santa Clarita1,72476712,2756.28
779Jan780Feb1,000Mar1,105Apr1,091May1,160Jun1,222Jul1,236Aug1,081Sep953Oct820Nov709DeckWh per month · Los Angeles
Estimate for comparison, not a quote: shading, roof orientation and local losses change real output. Roof mount, 20° tilt, south, 14% system losses.

About First Solar

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

Other series by SoCal permits

FS-6xxx-P-BFS-6xxxA-P-BFS-6xxxA-P-B-2FS-7xxxA-FT1FS-7xxxA-TR1FS-6xxxA-P

Questions & answers

How efficient is the First Solar FS-6445-P-B-2?

Calculated from the panel area (2.52 m²): about 17.7% for the 445 W class. 445 W over 2.52 m² equals about 177 W per square meter.

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

PVWatts v8 with typical-year weather gives about 746 kWh per year per 445 W panel in Los Angeles and about 817 kWh in Palmdale (20° roof, facing south, 14% system losses).

How much power does it lose on a hot roof?

With γ = −0.229 %/°C, at a 77 °C cell temperature (hottest modeled hour in Palmdale) output is about 11.9% 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 1–2 panels per string (Voc at 2 °C = 239.3 V, Vmp at 74 °C cell = 156.5 V). Final design must follow the inverter manual and NEC 690.7.

Has this panel been reliability-tested?

This exact series is not in published PVEL Top Performer tables; First Solar was named a Top Performer in 5 Scorecards (2018–2023).

Sources

  1. California Energy Commission — Solar Equipment Lists, PV Module List, Inverter List (snapshot Oct 7, 2026).
  2. Kiwa PVEL — PV Module Reliability Scorecard, Top Performer lists 2018–2023.
  3. NLR (formerly NREL) — System Advisor Model CEC inverter library (version 2026.7.3).
  4. NLR (formerly NREL) — PVWatts v8, NSRDB PSM v3 typical-year weather for Los Angeles, Palmdale, Chula Vista, Huntington Beach, Riverside, Santa Clarita.
  5. Inverter datasheets — APsystems (Alt Power System), Enphase, Solis (Ginlong), Tesla (manufacturer documents).
  6. Cali-Graf calculations — formulas and inputs are shown next to each calculated value (efficiency from area, temperature-corrected voltages, string sizing, energy estimates).