Solar Simulator Classifications |
The ASTM standard states:
"...a solar simulator may be one of three classes (A, B, or C) for each of three categories: spectral match, spatial non-uniformity, and temporal instability. The simulator is rated with three letters in order of spectral match, spatial non-uniformity and temporal instability (for example: Class ABA)."
We refer to the "class" of a specific solar simulator as being the lowest rating achieved across these three catagories. Thus, a simulator with a B class spectrum and A class spatial uniformity and temporal instability would have a rating of B/A/A and could be referred to as "Class B". This could also infer that the simulator has class B performance across all catagories. It is therefore required that the manufacturer clearly states the class performance of a solar simulator for each catagory.
The class specifications for the various standards are shown below.
"...a solar simulator may be one of three classes (A, B, or C) for each of three categories: spectral match, spatial non-uniformity, and temporal instability. The simulator is rated with three letters in order of spectral match, spatial non-uniformity and temporal instability (for example: Class ABA)."
We refer to the "class" of a specific solar simulator as being the lowest rating achieved across these three catagories. Thus, a simulator with a B class spectrum and A class spatial uniformity and temporal instability would have a rating of B/A/A and could be referred to as "Class B". This could also infer that the simulator has class B performance across all catagories. It is therefore required that the manufacturer clearly states the class performance of a solar simulator for each catagory.
The class specifications for the various standards are shown below.
ASTM class specifications
| Classification | Spectral Match (each interval) | Irradiance Spatial Non-Uniformity | 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% |
IEC class specifications
| Classification | Spectral Match (each interval) | Irradiance Spatial Non-Uniformity | Short-term Temporal Instability | Long-term Temporal Instability |
|---|---|---|---|---|
| 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% |
JIS class specifications
| Classification | Spectral Match (each interval) | Irradiance Spatial Non-Uniformity | Temporal Instability |
|---|---|---|---|
| Class A | 0.75–1.25 | 2% | 1% |
| Class B | 0.6–1.4 | 3% | 3% |
| Class C | 0.4–2.0 | 10% | 10% |
Note that while the standards are generally similar, there are key differences. The IEC standard provides for short and long term instability (STI and LTI respectively) while the ASTM standard differentiates simulator classifications for different areas of illumination and the JIS standard requires a lower temporal stability for class A than both the ASTM and IEC standards.
It is important, therefore, that the user is clear as to which standard they are required to meet when selecting a solar simulator
It is important, therefore, that the user is clear as to which standard they are required to meet when selecting a solar simulator