MT5 Multi-Tracer Operating Manual
page 30
The auxiliary associations work the same as the temperature associations.
The MT5 Multi-Tracer system does not have specific inputs for measuring irradiance.
However, it is common for some auxiliary inputs to be used for irradiance
measurements.
The “Associated Aux Irradiance” settings associate auxiliary inputs
specifically as irradiance measurements. This means that these values will be stored as
irradiance values in the module IV curve data files. This simply identifies the given
auxiliary inputs as irradiances values.