Illustration · 60 cells

Solar panelGermanSolar USA

GermanSolar USA GSP 325

Name: GermanSolar USA GSP 325
Brand: GermanSolar USA

60 cells. Power classes 270–355 W in the CEC list.

CEC listed · Apr 21, 2023UL 61730

Power class

Power (STC)325 WCEC nameplate
Efficiency≈16.4%calculated from area
%/°C Pmax−0.406CEC listing test
PTC / STC92%PTC 299 W (CEC)

Power classes

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation · 12 models

Model	Pmax	Voc, V	Isc, A	Vmp, V	Imp, A	Efficiency	PTC	CEC listed
GSP-270W	270 W	37.92	8.99	31.91	8.46	≈16.3%	248 W	Apr 21, 2023
GSP-275W	275 W	38.32	9.08	32.31	8.51	≈16.6%	253 W	Apr 21, 2023
GSP-280W	280 W	38.55	9.18	32.55	8.60	≈16.9%	258 W	Apr 21, 2023
GSP-285W	285 W	38.90	9.25	32.83	8.68	≈17.2%	263 W	Apr 21, 2023
GSP-320W	320 W	45.15	9.02	38.00	8.42	≈16.2%	294 W	Apr 21, 2023
GSP-325W	325 W	45.29	9.08	38.23	8.51	≈16.4%	299 W	Apr 21, 2023
GSP-330W	330 W	45.44	9.18	38.38	8.60	≈16.7%	304 W	Apr 21, 2023
GSP-335W	335 W	45.65	9.21	38.60	8.68	≈16.9%	308 W	Apr 21, 2023
GSP-340W	340 W	45.86	9.35	38.80	8.77	≈17.2%	313 W	Apr 21, 2023
GSP-345W	345 W	46.16	9.41	39.04	8.85	≈17.4%	318 W	Apr 21, 2023
GSP-350W	350 W	46.50	9.48	39.33	8.90	≈17.7%	323 W	Apr 21, 2023
GSP-355W	355 W	46.60	9.56	39.62	8.96	≈17.9%	327 W	Apr 21, 2023

≈ efficiency = Pmax ÷ CEC-listed area 1.66 m².

Heat & cold behaviour

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

	CEC listing test
Pmax coefficient γ	−0.406 %/°C
Voc coefficient β	−0.324 %/°C
Isc coefficient α	+0.053 %/°C
Operating cell temperature	NOCT 44.1 °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
270 W	209.7 W	29.92 V × 7.01 A	55.1 W	102%
275 W	213.6 W	30.3 V × 7.05 A	56.2 W	102%
280 W	217.5 W	30.52 V × 7.12 A	57.2 W	102%
285 W	221.4 W	30.79 V × 7.19 A	58.2 W	102%
320 W	231.7 W	35 V × 6.62 A	62.5 W	98%
325 W	235.5 W	35.21 V × 6.69 A	63.5 W	98%
330 W	239 W	35.35 V × 6.76 A	64.5 W	98%
335 W	242.6 W	35.55 V × 6.82 A	65.4 W	98%
340 W	246.4 W	35.73 V × 6.89 A	66.4 W	98%
345 W	250.1 W	35.95 V × 6.96 A	67.5 W	98%
350 W	253.4 W	36.22 V × 7 A	68.4 W	98%
355 W	257 W	36.49 V × 7.04 A	69.3 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

48.7 V

Voc when cold

per panel

29.6 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	3–12
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)

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	48.7 / 29.6 V	✓ Within range	1.12
Enphase IQ8X-80-M-US	320–540 W	79.5 V	43–60 V	48.7 / 29.6 V	✗ Not a match: module voltage below MPPT range	0.86
APsystems (Alt Power System) DS3-L	265–570 W	60 V	28–45 V	48.7 / 29.6 V	✓ Within range	0.42
Enphase IQ8M-72-2-US	260–460 W	60 V	30–45 V	48.7 / 29.6 V	⚠ Works; below MPPT at peak heat	1
Enphase IQ8A-72-2-US	295–500 W	60 V	32–45 V	48.7 / 29.6 V	⚠ Works; below MPPT at peak heat	0.93

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	545	11,983	6.08
Palmdale	1,835	596	13,120	6.69
Chula Vista	1,696	551	12,126	6.11
Huntington Beach	1,643	534	11,747	5.89
Riverside	1,696	551	12,126	6.21
Santa Clarita	1,724	560	12,327	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 325 W panels

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

Panel	Pmax	Efficiency	γ Pmax (CEC)	Voc, V	Isc, A	Size	Warranty	PVEL (product / brand)	SoCal permits (series)
GermanSolar USA GSP 325	325 W	≈16.4%	−0.406	45.29	9.08	—	—	—	—
JinkoSolar JKM325M-60HBL	325 W	≈19.3%	−0.407	41.1	10.2	66.3 × 39.4 in	10 / 25 yr	brand 12× (2014–2026)	45
Qcells Q.PEAK DUO-G8+ 330	330 W	≈18.4%	−0.343	39.71	10.52	68.5 × 40.6 in	25 / 25 yr	product 2022	20
LG Electronics LG325N1C-N5	325 W	≈18.8%	−0.342	40.9	10.57	66.9 × 40 in	25 / 25 yr	product 2021	5

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 GSP 325?

Calculated from the panel area (1.98 m²): about 16.4% for the 325 W class. 325 W over 1.98 m² equals about 164 W per square meter.

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

PVWatts v8 with typical-year weather gives about 545 kWh per year per 325 W panel in Los Angeles and about 596 kWh in Palmdale (20° roof, facing south, 14% system losses).

How much power does it lose on a hot roof?

With γ = −0.406 %/°C, at a 77 °C cell temperature (hottest modeled hour in Palmdale) output is about 21.1% 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 3–12 panels per string (Voc at 2 °C = 48.7 V, Vmp at 74 °C cell = 29.6 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 48.7 V vs max input 60 V; Vmp when hot 29.6 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).
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”.
LG Electronics — datasheet Specification Sheet.
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).