Solar Simulator Standards – Definitions & Comparisons

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.

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.

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.

For measurements over multiple time intervals, typically at the same spot of the illumination area.

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 A, which is better than Class B and 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.

The three compliance standards that define solar simulator performance are:

• IEC 60904-9 (2020) 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

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, and up to A+ Spectral Match with our Solaris series. 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.

Additionally, our Sol-UV Ultraviolet Solar Simulators provide UV light for demanding applications in photobiology. All Sol-UV simulators spectral output are certified to be compliant to FDA CFR Part 201.327, ISO 24444:2019(E) Second Edition, ISO 24443:2021(E) Second 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.