Technical Note:
Solar Simulator Standards – Definitions & Comparisons

Overview

A solar simulator is a light source that approximates the illumination of natural sunlight. The ability of a solar simulator to approximate natural sunlight is based on three criteria: (1) spectral match, (2) spatial non-uniformity of irradiance and (3) temporal instability. This technical note describes each of these criteria and the three international compliance standards used to define solar simulator performance.


Spectral Match

As the output of a solar simulator is white light, spectral match defines how well its distribution of irradiance among different wavelengths approximates natural sunlight. Spectral match is therefore a measurement of the distribution of irradiance across six defined wavelength ranges (bins) as a percentage of the total irradiance.

Class A Simulator Spectral Match

Spatial Non-Uniformity

Since hot spots can lead to significant errors, spatial uniformity – the most difficult criteria to achieve and maintain – is a measure of how the irradiance varies over a defined area. This is expressed as non-uniformity, i.e., the maximum and minimum percentage differences from the mean irradiance.

Max-Min Irradiance Equation
For measurements across the entire illumination area during one moment in time.
Uniformity Analysis

Temporal Instability

The output of a solar simulator must be stable over time to ensure that lamp fluctuations (i.e., flickering) do not distort measurements. To measure temporal instability, variations of lamp power and current are monitored (typically at the same spot of the illumination area) and presented as a maximum-over-minimum average for the observations.

Max-Min Irradiance Equation
For measurements over multiple time intervals, typically at the same spot of the illumination area.
Temporal_Fig4

Criteria Classifications

Solar simulators are characterized by a three-letter code that classifies each of the three criteria. The first code classifies spectral match, the second code classifies spatial non-uniformity, and the third code classifies temporal instability. Class A is the most stringent requirement and therefore indicates better performance than Class B, which is better than Class C. For example, a Class AAA solar simulator meets Class A requirements for all criteria, whereas a Class ABA solar simulator meets Class A requirements for spectral match and temporal instability but Class B requirements for spatial non-uniformity.

International Compliance Standards

The three compliance standards that define solar simulator performance are:

  • IEC 60904-9 Edition 2 (2007) Photovoltaic Devices – Part 9: Solar Simulator Performance Requirements
  • JIS C 8904-9 (2017), Part 9: Solar Simulator Performance Requirements
  • ASTM E 927-10 (2010) Standard Specification for Solar Simulation for Terrestrial Photovoltaic Testing
Each standard's requirements for spectral match, spatial non-uniformity and temporal instability are described below.

IEC 60904-9 Compliance Standards

Class A, B and C Standards and
Specifications Defined by IEC 60904-9

Spectral Match* Non-Uniformity of Irradiance Temporal Instability, Short-term Temporal Instability, Long-term
Class A 0.75-1.25 2% 0.5% 2%
Class B 0.6-1.4 5% 2% 5%
Class C 0.4-2.0 10% 10% 10%

* Acceptable range ratio of ideal % according to related table values for 'Ideal Spectral Match' standards for IEC 60904-9.

Ideal Spectral Match Defined by IEC 60904-9

Spectral Range (nm) Total Irradiance Range Ideal Percentage
400-500 13.8-23.0 18.4%
500-600 14.9-24.9 19.9%
600-700 13.8-23.0 18.4%
700-800 11.2-18.6 14.9%
800-900 9.4-15.6 12.5%
900-1100 11.9-19.9 15.9%

JIS C 8904-9 Compliance Standards

Class A, B and C Standards and
Specifications Defined by JIS C 8904-9

Spectral Match* Non-Uniformity of Irradiance Temporal Instability,
Short-term
Temporal Instability,
Long-term
Class A 0.75-1.25 ±2% 0.5% 2%
Class B 0.6-1.4 ±3% 2% 5%
Class C 0.4-2.0 ±10% 10% 10%

* Acceptable range ratio of ideal % according to related table values for 'Ideal Spectral Match' standards for JIS C 8904-9

Ideal Spectral Match Defined by
JIS C 8904-9 for Crystalline Silicon

Spectral Range (nm) Total Irradiance Range Ideal Percentage
400-500 13.8-23.0 18.4%
500-600 14.9-24.9 19.9%
600-700 13.8-23.0 18.4%
700-800 11.2-18.6 14.9%
800-900 9.4-15.6 12.5%
900-1100 11.9-19.9 15.9%

ASTM E 927-10 Compliance Standards

Class A, B and C Standards and
Specifications Defined by ASTM E 927-10

Spectral Match* Non-Uniformity of Irradiance Temporal Instability
Class A 0.75-1.25 2% 2%
Class B 0.6-1.4 5% 5%
Class C 0.4-2.0 10% 10%

* Acceptable range ratio of ideal % according to related table values for 'Ideal Spectral Match' standards for ASTM E 927-10

Ideal Spectral Match Defined by
ASTM E 927-10

Spectral Range (nm) Total Irradiance Range Ideal Percentage
400-500 13.8-23.0 18.4%
500-600 14.9-24.9 19.9%
600-700 13.8-23.0 18.4%
700-800 11.2-18.6 14.9%
800-900 9.4-15.6 12.5%
900-1100 11.9-19.9 15.9%

Newport Oriel Solar Simulators

Oriel Solar Simulators provide the closest spectral match to the sun available from any light source, with all Oriel Solar Simulators meeting class A specifications for this first criteria. Our offering includes systems with varying levels of performance for the two additional criteria according to your application requirements. Newport provides a calibration certificate and the test data validating performance for all three compliance standards. Below is a summary of our solar simulators and their classifications.

Classification Product Series Lamp Type Model Numbers
AAA Sol3A Xenon 94023A, 94043A, 94063A, 94083A, 94123A, 94123A-CPV
ABA Sol2A Xenon 94042A, 94062A, 94082A
ABB Sol1A Xenon 94041A, 94061A, 94081A
ABB LCS-100 Small Area Xenon 94011A, 94011A-ES
AAA VeraSol-2 LED VeraSol-2
ABA MiniSol LED LSH-7320

Additionally, our Sol-UV Ultraviolet Solar Simulators provide UV light for demanding applications in photobiology. Their spectral outputs are certified to be compliant to FDA CFR Part 201.327, ISO 24444:2010(e) First Edition, and the International SPF Test Method (CTFASA/COLIPA/JCIA/CTFA): May 2006 for Spectral Match. With an optional filter, it can deliver JCIA UVA compliant output.