infinityPV ApS offers the CalCell reference device which is a calibrated photodiode with filter that you can use to calibrate the intensity of you solar simulator at the position of your device under test. The infinityPV ISOSun solar simulators have internal reference diodes that serve the purpose of monitoring the light source at a fixed geometry. You then always know if your lamp is set correctly or whether it is the same as last time. The light intensity at the actual position of your sample however depends on several factors including your sample geometry, fixture, position etc. By placing the CalCell reference device in the position of your sample you accurately measure light intensity there.