benchmarks/industry_techspec/cec_pv_module/data/README.md

data/ -- CEC certified PV module database (Sandia / CEC 5-parameter single-diode)

Source

• Primary registry: California Energy Commission "Solar Equipment Lists -- Photovoltaic Modules", https://solarequipment.energy.ca.gov/Home/PVModuleList (CEC maintains the list; updated monthly as new modules are certified).
• Snapshot used: the database bundled with pvlib-python, accessed via pvlib.pvsystem.retrieve_sam("CECMod"). This is the SAM (NREL System Advisor Model) snapshot of the CEC list that ships inside pvlib/data/sam-library-cec-modules-*.csv. The snapshot in this benchmark corresponds to pvlib version >= 0.10.
• Primary technical references:
  • De Soto, Klein, Beckman 2006, Improvement and validation of a model for photovoltaic array performance, Solar Energy 80(1):78-88, doi:10.1016/j.solener.2005.06.010 -- defines the 5-parameter single-diode model whose parameters each CEC row carries. Full derivation is in De Soto's 2004 MS thesis at UW-Madison (../reference/desoto2004_thesis.pdf).
  • King, Boyson, Kratochvil 2004, Photovoltaic Array Performance Model, SAND2004-3535, https://www.osti.gov/biblio/919131 -- defines the PTC test conditions and the empirical temperature-response model used by the CEC certification process (../reference/king2004_sapm.pdf).
• Retrieved on: 2026-04-22.
• License: California state government open data (public). The CEC list is a public registry and the pvlib snapshot is redistributed under the pvlib BSD-3-Clause license with attribution to CEC / NREL.

Each row is a PV module certified by an accredited test laboratory (TUV, SGS, ETL, Intertek) against the Sandia / CEC 5-parameter single-diode model, with parameters (a_ref, I_L_ref, I_o_ref, R_s, R_sh_ref) fitted by SAM to match the manufacturer datasheet key points (I_sc_ref, V_oc_ref, I_mp_ref, V_mp_ref, P_mp_stc) at STC, plus temperature coefficients measured under NOCT.

How to rebuild data.csv

bash download.sh

The script installs pvlib (via pip install pvlib) if it is not already present, calls pvlib.pvsystem.retrieve_sam("CECMod"), transposes the module-as-column layout into one-module-per-row, enforces a stable column order, and writes the result to data.csv. The whole process is offline once pvlib is installed; the CEC database is bundled inside the pvlib wheel.

Columns

21 535 modules x 26 columns. Column 0 is the primary output; columns 1..25 are inputs / metadata kept verbatim from upstream so that alternative ground-truth formulas can be added later without re-fetching the data.

index	name	units	type	description
0	P_mp_stc	W	output (float)	Output. Module max-power-point power at STC (1000 W/m^2, 25 deg C, AM1.5). Stored as STC upstream; renamed for clarity. By CEC convention P_mp_stc == I_mp_ref * V_mp_ref exactly.
1	I_sc_ref	A	input (float)	Short-circuit current at STC.
2	V_oc_ref	V	input (float)	Open-circuit voltage at STC.
3	I_mp_ref	A	input (float)	Current at the max-power operating point at STC.
4	V_mp_ref	V	input (float)	Voltage at the max-power operating point at STC.
5	alpha_sc	A/K	input (float)	I_sc temperature coefficient (SAPM convention).
6	beta_oc	V/K	input (float)	V_oc temperature coefficient.
7	gamma_r	%/K	input (float)	Relative P_mp temperature coefficient.
8	T_NOCT	deg C	input (float)	Nominal Operating Cell Temperature (test conditions: 800 W/m^2, 20 deg C air, 1 m/s wind).
9	a_ref	V	input (float)	Modified ideality factor a = n * N_s * k * T_cell / q at STC. One of the 5 De Soto parameters.
10	I_L_ref	A	input (float)	Light-generated (photo) current at STC. De Soto parameter.
11	I_o_ref	A	input (float)	Diode reverse-saturation current at STC. De Soto parameter.
12	R_s	Ohm	input (float)	Series resistance (lumped). De Soto parameter.
13	R_sh_ref	Ohm	input (float)	Shunt resistance at STC. De Soto parameter.
14	Adjust	%	input (float)	SAM empirical I_sc vs. alpha_sc adjustment factor.
15	N_s	count	input (int)	Number of cells connected in series in the module.
16	A_c	m^2	input (float)	Module aperture area.
17	Length	m	input (float)	Module length.
18	Width	m	input (float)	Module width.
19	PTC	W	input (float)	Power at PVUSA Test Conditions (1000 W/m^2, 20 deg C air, 1 m/s wind).
20	Technology	--	input (str)	Mono-c-Si / Multi-c-Si / Thin Film / CdTe / CIGS.
21	Bifacial	bool	input (0/1)	Bifacial construction flag.
22	BIPV	--	input (Y/N)	Building-integrated PV flag.
23	module_id	--	identifier (str)	Manufacturer + model string (unique).
24	Version	--	provenance (str)	SAM DB version that generated the row.
25	Date	--	provenance (str)	SAM DB entry date.

Columns consumed by the shipped ground-truth formulas

• single_diode_pmp: I_L_ref, I_o_ref, R_s, R_sh_ref, a_ref (the 5 De Soto parameters).
• power_from_imp_vmp: I_mp_ref, V_mp_ref.
• efficiency_area_scaling: A_c.

All other columns are retained for future ground-truth additions (e.g. SAPM PTC temperature correction, per-technology efficiency fits, V_oc from simplified diode, ...) -- see ../description.md.

Shape

21 535 rows x 26 columns.

Notes on the upstream table

• The five single-diode parameters (a_ref, I_L_ref, I_o_ref, R_s, R_sh_ref) are not directly measured: CEC's accredited labs measure the I-V curve under STC and NOCT, and SAM fits the 5 parameters so that the resulting De Soto I-V curve matches the measured (I_sc, V_oc, I_mp, V_mp, alpha_sc, beta_oc). Consequently the single-diode formula single_diode_pmp.f(X) reproduces P_mp_stc to numerical precision -- this is by construction and is the intended upper bound / physics check for the benchmark.
• A handful of older entries have I_o_ref so small (< 1e-18 A) that the single-diode solver hits its lower numeric bound. The bundled scorer treats these rows as valid and they do not materially affect aggregate metrics.
• Technology counts in this snapshot: 11 221 Multi-c-Si, 9 725 Mono-c-Si, 561 Thin Film, 20 CdTe, 8 CIGS. 133 modules are flagged bifacial.