Solar Simulators and I-V Measurement Methods

Large differences in reported efficiency can occur because of differences in area definition and measurement, spectral mismatch errors and reference cell calibration. The performance of a solar simulator is site specific. A simulator bulb type, age, current and alignment can affect the spatial uniformity, temporal stability and spectral irradiance of the simulator. Alignment and cleanliness of the simulator optics will affect the spatial uniformity and spectral irradiance. The measurement procedures including corrections for intensity fluctuations and measurement of the simulator intensity with a reference cell will affect the accuracy and repeatability of I-V measurements. The spectral irradiance of the solar simulator should be measured periodically on site for spectral mismatch calculations. Not all outdoor clear sky spectra satisfy class A solar simulator requirements or match a reference spectrum as well as pulsed Xe arc solar simulators.