Effective Irradiance Ratios to Improve I–V Curve Measurements and Diode Modeling Over a Range of Temperature and Spectral and Total Irradiance

Abstract

We present an integrated measurement and modeling approach based on the effective irradiance ratio, which is simply the ratio of the short-circuit current of a photovoltaic (PV) device under operating conditions to its short-circuit current under standard test conditions. Using a PV reference device to measure effective irradiance with respect to a standard spectrum, this approach handles device-specific and reference-device-specific temperature and spectral irradiance effects that are significant factors in performance measurements, such as IEC 61853-1, as well as in the diode-based equivalent circuit performance models that are calibrated from such measurements. Avoiding the use of spectrally dependent short-circuit current temperature coefficients, this approach uses a temperature-dependent spectral correction function that is a direct extension of the standardized spectral correction parameter used by numerous PV calibration laboratories. When a matched reference device is used, this function becomes identically one, and it need not be computed. This approach should be useful in the advancement of PV performance testing and modeling that use reference devices to monitor irradiance.