Illustration · 132 half-cut cells

Solar panelREC Group

REC Group REC660AA Pro L

Name: REC Group REC660AA Pro L
Brand: REC Group

132 half-cut cells, bifacial. Power classes 650–680 W in the CEC list.

CEC listed · Sep 1, 2023UL 61730BifacialPVEL Top Performer 2025

Power class

Power (STC)660 WCEC nameplate
Efficiency≈21.6%calculated from area
%/°C Pmax−0.327CEC listing test
PTC / STC93.7%PTC 618 W (CEC)

Power classes

CEC PV Module List (Oct 7, 2026) · Cali-Graf calculation · 4 models

Model	Pmax	Voc, V	Isc, A	Vmp, V	Imp, A	Efficiency	PTC	CEC listed
REC650AA Pro L	650 W	49.10	16.14	42.20	15.40	≈21.2%	609 W	Sep 1, 2023
REC660AA Pro L	660 W	49.20	16.35	42.40	15.60	≈21.6%	618 W	Sep 1, 2023
REC670AA Pro L	670 W	49.20	16.55	42.50	15.79	≈21.9%	628 W	Sep 1, 2023
REC680AA Pro L	680 W	49.30	16.76	42.60	16.01	≈22.2%	638 W	Sep 1, 2023

≈ efficiency = Pmax ÷ CEC-listed area 3.06 m².

Heat & cold behaviour

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

	CEC listing test
Pmax coefficient γ	−0.327 %/°C
Voc coefficient β	−0.266 %/°C
Isc coefficient α	+0.042 %/°C
Operating cell temperature	NOCT 45.6 °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	488.8 W	38 V × 12.87 A	122 W	94%
660 W	497.5 W	38.18 V × 13.03 A	124.2 W	94%
670 W	504.8 W	38.27 V × 13.19 A	126 W	94%
680 W	513 W	38.36 V × 13.37 A	128.1 W	94%

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 · RETC PV Module Index

2025

PVEL Top Performer

this series

Tests passed as Top Performer

PAN, PID

PVEL Scorecards

REC Group named Top Performer, 2016–2025

RETC PV Module Index

REC Group recognized 2023–2025

PVEL Top Performer tests

Year	Product	Tests
2025	RECxxxAA Pro L	PANPID

Tested bill of materials

PVEL-tested factorySingapore
Cell technology (tested BOM)n-type HJT
Module design (tested BOM)bifacial - 2.0 glass//2.0 glass
Power class range tested680-725W

Details describe the tested sample, not every module of the series.

RETC PV Module Index — REC Group

Year	Recognition
2023	High Achievement in Performance (Ptc-to-stc ratio, Module efficiency)
2024	High Achievement in Performance
2025	Test Category High Achiever

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

52.2 V

Voc when cold

per panel

34.7 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	3–11
Qcells Q.VOLT H7.6SX	498 V	234–498 V	CEC test window	7–9

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.

About REC Group

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

ManufacturerREC Group
Listed in CEC asREC Group
PVEL Top Performer (manufacturer)9 Scorecards (2016–2025)
RETC PV Module Index2023, 2024, 2025
Current panel series in CEC list26

Other series by SoCal permits

RECxxxAA Pure · 66RECxxxAA Pure-RX · 33RECxxxAA · 30RECxxxAA Black · 8RECxxxNP3 Black · 7RECxxxAA Pure 2 · 6

Questions & answers

How efficient is the REC Group REC660AA Pro L?

Calculated from the panel area (3.06 m²): about 21.6% for the 660 W class. 660 W over 3.06 m² equals about 216 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 = −0.327 %/°C, at a 77 °C cell temperature (hottest modeled hour in Palmdale) output is about 16.9% 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 2–11 panels per string (Voc at 2 °C = 52.2 V, Vmp at 74 °C cell = 34.7 V). Final design must follow the inverter manual and NEC 690.7.

Is it bifacial?

Yes. Rear gain depends on mounting height and ground reflectance.

Has this panel been reliability-tested?

RECxxxAA Pro L was a PVEL Top Performer in 2025 (PAN, PID).

Sources

California Energy Commission — Solar Equipment Lists, PV Module List, Inverter List (snapshot Oct 7, 2026).
Kiwa PVEL — PV Module Reliability Scorecard, Top Performer lists 2016–2025.
RETC — PV Module Index reports 2023–2025.
NLR (formerly NREL) — System Advisor Model CEC module and inverter libraries (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).
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).