Illustration · 132 cells

Solar panelG-Star

G-Star GSD8J66M-660WT

Name: G-Star GSD8J66M-660WT
Brand: G-Star

132 cells. Power classes 650–675 W in the CEC list.

CEC listed · Feb 12, 2024UL 61730

Power class

Power (STC)660 WCEC nameplate
Efficiency≈21.4%calculated from area
%/°C Pmax−0.336CEC listing test
PTC / STC94.2%PTC 622 W (CEC)

Power classes

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation · 6 models

Model	Pmax	Voc, V	Isc, A	Vmp, V	Imp, A	Efficiency	PTC	CEC listed
GSD8J66M-650WT	650 W	45.40	18.21	37.60	17.29	≈21.1%	612 W	Feb 12, 2024
GSD8J66M-655WT	655 W	45.60	18.26	37.80	17.33	≈21.3%	617 W	Feb 12, 2024
GSD8J66M-660WT	660 W	45.80	18.31	38.00	17.37	≈21.4%	622 W	Feb 12, 2024
GSD8J66M-665WT	665 W	46.00	18.36	38.20	17.41	≈21.6%	626 W	Feb 12, 2024
GSD8J66M-670WT	670 W	46.20	18.41	38.40	17.45	≈21.8%	631 W	Feb 12, 2024
GSD8J66M-675WT	675 W	46.40	18.46	38.60	17.49	≈21.9%	636 W	Feb 12, 2024

≈ efficiency = Pmax ÷ CEC-listed area 3.08 m².

Build & dimensions

CEC PV Module List (Oct 7, 2026)

Module area3.08 m² (33.2 ft²)CEC-listed area
Cells132 cells
Back coverGlass (dual-glass module)

Heat & cold behaviour

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

	CEC listing test
Pmax coefficient γ	−0.336 %/°C
Voc coefficient β	−0.289 %/°C
Isc coefficient α	+0.047 %/°C
Operating cell temperature	NOCT 43.4 °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
650 W	485.1 W	35.41 V × 13.7 A	124 W	95%
655 W	488.8 W	35.6 V × 13.73 A	125 W	95%
660 W	492.6 W	35.79 V × 13.76 A	125.9 W	95%
665 W	496.3 W	35.97 V × 13.8 A	126.9 W	95%
670 W	500 W	36.16 V × 13.83 A	127.9 W	95%
675 W	503.8 W	36.35 V × 13.86 A	128.8 W	95%

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

CityColdest air, °CHottest cell, °CString inverter

48.8 V

Voc when cold

per panel

30.9 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	2–12
Solis (Ginlong) S6-EH1P10K-H-US	600 V	80–520 V	datasheet	3–12
Solis (Ginlong) Solis-1P7.6K-4G-US	600 V	100–500 V	datasheet	4–12
Qcells Q.VOLT H7.6SX	498 V	234–498 V	CEC test window	8–10

Microinverters (one per panel)

No microinverter in the reference set lists this power class in its recommended module power range.

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	1,106	12,168	6.08
Palmdale	1,835	1,211	13,322	6.69
Chula Vista	1,696	1,119	12,313	6.11
Huntington Beach	1,643	1,084	11,928	5.89
Riverside	1,696	1,119	12,313	6.21
Santa Clarita	1,724	1,138	12,516	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 G-Star GSD8J66M-660WT?

Calculated from the panel area (3.08 m²): about 21.4% for the 660 W class. 660 W over 3.08 m² equals about 214 W per square meter.

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

PVWatts v8 with typical-year weather gives about 1,106 kWh per year per 660 W panel in Los Angeles and about 1,211 kWh in Palmdale (20° roof, facing south, 14% system losses).

How much power does it lose on a hot roof?

With γ = −0.336 %/°C, at a 77 °C cell temperature (hottest modeled hour in Palmdale) output is about 17.4% 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 2–12 panels per string (Voc at 2 °C = 48.8 V, Vmp at 74 °C cell = 30.9 V). Final design must follow the inverter manual and NEC 690.7.

Sources

California Energy Commission — Solar Equipment Lists, PV Module List, Inverter List (snapshot Oct 7, 2026).
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 — Solis (Ginlong), Tesla (manufacturer documents).
Cali-Graf calculations — formulas and inputs are shown next to each calculated value (efficiency from area, temperature-corrected voltages, string sizing, energy estimates).