Reconciling LED and Monochromator-based Measurements of Spectral Responsivity
John F. Roller, Behrang H. Hamadani
The irradiance spectral responsivity is an important measurement characteristic for a reference solar cell and has served as a primary reference cell calibration method for a growing number of national labs in recent years. This paper discusses the process by which a packaged reference cell is calibrated using a power spectral responsivity from a monochromator-based measurement coupled with discrete irradiance responsivity measurements from an integrating sphere-coupled light emitting diode (LED) array source to uniformly illuminate the cell. To accurately transfer the responsivity from a calibrated detector cell to a fully packaged reference cell, differences in the measurements of power and irradiance responsivities due to the two separate lighting sources must be reconciled. The spectral effects of using LEDs for the overfill condition, as well as other physical packaging effects, are discussed in detail.