Spectral mismatch considerations in multi-irradiance characterization of PV modules

Determination of the energy yield of a PV module requires knowledge of its response over a range of irradiance. When such testing is done with pulsed xenon solar simulator with adjustable irradiance output and an irradiance monitor device which has a different spectral response than the device under test, the spectral mismatch factor may vary with the irradiance set-point. This work describes the extent of measurement errors which may occur if variance in spectral mismatch is neglected. Comparison of the measured response of several different PV technologies over an irradiance range of 200 to 1000W/m² is made with estimates based upon spectral mismatch calculations. Reduction in measurement error by the use of irradiance monitor devices having a spectral response that is well-matched to that of the device under test is shown, and the impact of such measurement errors on estimated energy yields obtained with PV system software is evaluated.