Illustration · 60 cells

Solar panelGermanSolar USA

GermanSolar USA GSM 370

Name: GermanSolar USA GSM 370
Brand: GermanSolar USA

60 cells. Power classes 300–410 W in the CEC list.

CEC listed · Apr 21, 2023UL 61730

Power class

Power (STC)370 WCEC nameplate
Efficiency≈18.7%calculated from area
%/°C Pmax−0.397CEC listing test
PTC / STC92.6%PTC 343 W (CEC)

Power classes

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation · 17 models

Model	Pmax	Voc, V	Isc, A	Vmp, V	Imp, A	Efficiency	PTC	CEC listed
GSM-300W	300 W	39.85	9.76	33.86	8.86	≈18.0%	278 W	Apr 21, 2023
GSM-305W	305 W	40.08	9.84	34.14	8.94	≈18.3%	282 W	Apr 21, 2023
GSM-310W	310 W	40.32	9.92	34.38	9.02	≈18.6%	287 W	Apr 21, 2023
GSM-315W	315 W	40.50	9.98	34.56	9.12	≈18.9%	292 W	Apr 21, 2023
GSM-320W	320 W	40.74	10.05	34.80	9.20	≈19.2%	297 W	Apr 21, 2023
GSM-325W	325 W	41.05	10.10	35.13	9.25	≈19.5%	301 W	Apr 21, 2023
GSM-330W	330 W	41.40	10.17	35.44	9.31	≈19.8%	306 W	Apr 21, 2023
GSM-365W	365 W	47.45	9.68	40.24	9.08	≈18.4%	338 W	Apr 21, 2023
GSM-370W	370 W	48.02	9.77	40.39	9.17	≈18.7%	343 W	Apr 21, 2023
GSM-375W	375 W	48.09	9.86	40.53	9.26	≈18.9%	348 W	Apr 21, 2023
GSM-380W	380 W	48.45	9.90	40.86	9.30	≈19.2%	352 W	Apr 21, 2023
GSM-385W	385 W	48.53	10.07	41.08	9.37	≈19.4%	357 W	Apr 21, 2023
GSM-390W	390 W	48.86	10.10	41.40	9.42	≈19.7%	362 W	Apr 21, 2023
GSM-395W	395 W	49.32	10.17	41.57	9.50	≈19.9%	366 W	Apr 21, 2023
GSM-400W	400 W	49.50	10.26	41.79	9.57	≈20.2%	371 W	Apr 21, 2023
GSM-405W	405 W	50.10	10.26	42.00	9.65	≈20.5%	376 W	Apr 21, 2023
GSM-410W	410 W	50.40	10.30	42.30	9.69	≈20.7%	381 W	Apr 21, 2023

≈ efficiency = Pmax ÷ CEC-listed area 1.67 m².

Heat & cold behaviour

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

	CEC listing test
Pmax coefficient γ	−0.397 %/°C
Voc coefficient β	−0.299 %/°C
Isc coefficient α	+0.050 %/°C
Operating cell temperature	NOCT 43.8 °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
300 W	222.9 W	29.62 V × 7.53 A	59.5 W	99%
305 W	226.8 W	29.87 V × 7.59 A	60.5 W	99%
310 W	230.5 W	30.08 V × 7.66 A	61.5 W	99%
315 W	234.2 W	30.23 V × 7.75 A	62.5 W	99%
320 W	237.9 W	30.44 V × 7.81 A	63.5 W	99%
325 W	241.5 W	30.73 V × 7.86 A	64.5 W	99%
330 W	245.2 W	31 V × 7.91 A	65.5 W	99%
365 W	263.8 W	36.93 V × 7.14 A	71.7 W	98%
370 W	267.4 W	37.06 V × 7.22 A	72.6 W	98%
375 W	271 W	37.19 V × 7.29 A	73.6 W	98%
380 W	274.4 W	37.49 V × 7.32 A	74.5 W	98%
385 W	277.9 W	37.7 V × 7.37 A	75.5 W	98%
390 W	281.6 W	37.99 V × 7.41 A	76.5 W	98%
395 W	285.1 W	38.15 V × 7.47 A	77.4 W	98%
400 W	288.8 W	38.35 V × 7.53 A	78.4 W	98%
405 W	292.6 W	38.54 V × 7.59 A	79.5 W	98%
410 W	296 W	38.82 V × 7.62 A	80.4 W	98%

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

51.3 V

Voc when cold

per panel

31.6 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	2–11
Solis (Ginlong) S6-EH1P10K-H-US	600 V	80–520 V	datasheet	3–11
Solis (Ginlong) Solis-1P7.6K-4G-US	600 V	100–500 V	datasheet	4–11
Qcells Q.VOLT H7.6SX	498 V	234–498 V	CEC test window	8–9

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	51.3 / 31.6 V	✓ Within range	1.28
Enphase IQ8X-80-M-US	320–540 W	79.5 V	43–60 V	51.3 / 31.6 V	✗ Not a match: module voltage below MPPT range	0.97
APsystems (Alt Power System) DS3-L	265–570 W	60 V	28–45 V	51.3 / 31.6 V	✓ Within range	0.47
Enphase IQ8M-72-2-US	260–460 W	60 V	30–45 V	51.3 / 31.6 V	✓ Within range	1.14
Enphase IQ8A-72-2-US	295–500 W	60 V	32–45 V	51.3 / 31.6 V	⚠ Works; below MPPT at peak heat	1.06

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	620	11,782	6.08
Palmdale	1,835	679	12,900	6.69
Chula Vista	1,696	628	11,923	6.11
Huntington Beach	1,643	608	11,550	5.89
Riverside	1,696	628	11,923	6.21
Santa Clarita	1,724	638	12,120	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 370 W panels

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

Panel	Pmax	Efficiency	γ Pmax (CEC)	Voc, V	Isc, A	PVEL (product / brand)	SoCal permits (series)
GermanSolar USA GSM 370	370 W	≈18.7%	−0.397	48.02	9.77	—	—
LONGi LR4-60HPB-370M	370 W	≈20.9%	−0.339	41.2	11.5	product 2021, 2022	193
Canadian Solar CS3N-375MS {Blk}	375 W	≈19%	−0.342	43.5	11.2	product 2023	46
REC Group REC370AA	370 W	≈21.9%	−0.258	44.1	10.55	brand 9× (2016–2025)	30

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 GermanSolar USA GSM 370?

Calculated from the panel area (1.98 m²): about 18.7% for the 370 W class. 370 W over 1.98 m² equals about 187 W per square meter.

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

PVWatts v8 with typical-year weather gives about 620 kWh per year per 370 W panel in Los Angeles and about 679 kWh in Palmdale (20° roof, facing south, 14% system losses).

How much power does it lose on a hot roof?

With γ = −0.397 %/°C, at a 77 °C cell temperature (hottest modeled hour in Palmdale) output is about 20.5% 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 2–11 panels per string (Voc at 2 °C = 51.3 V, Vmp at 74 °C cell = 31.6 V). Final design must follow the inverter manual and NEC 690.7.

Does it work with Enphase IQ8PLUS-72-2-US microinverters?

Voltage check against the Enphase datasheet: Voc when cold 51.3 V vs max input 60 V; Vmp when hot 31.6 V vs MPPT low 29 V; recommended module power 235–440 W. Confirm on the microinverter maker’s compatibility list.

Sources

California Energy Commission — Solar Equipment Lists, PV Module List, Inverter List (snapshot Oct 7, 2026).
Canadian Solar — manufacturer datasheet “HiKu Mono PERC CS3N-400|405|410|415|420|425MS MORE POWER”.
Kiwa PVEL — PV Module Reliability Scorecard, Top Performer lists.
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).