Calibration of a Single-Diode Performance Model without a Short-Circuit Temperature Coefficient
Mark Campanelli, Behrang Hamadani
We calibrate (i.e., fit the parameters of) a seven-parameter single-diode model (SDM) for photovoltaic device performance using current-voltage (I-V) curves measured under controlled laboratory conditions over a matrix of temperature and nominal irradiance combinations. As described in previous work , we avoid employing a short-circuit temperature coefficient parameter in the model. This coefficient depends on the often unknown insolation spectrum , , and a recent analysis of SDM parameter databases has questioned the validity of many values for this parameter reported without the relevant spectral information . Alternatively, we employ a rigorous temperature dependent extension of the spectral mismatch correction , , . This standard correction is routinely used by calibration laboratories to measure an effective irradiance ratio (i.e., a particular ratio of short-circuit currents) using a calibrated reference device, thereby compensating for spectral effects of the irradiance and for any difference in spectral responsivity between the reference and test devices. Bearing in mind the potential imperfections of the SDM, the calibrated seven-parameter model predicts the device's current at any prescribed voltage, temperature, and effective irradiance, and thus predicts power and energy production under prescribed conditions. Our approach aligns well with the matched reference cell approach to outdoor I-V curve measurements , , while clarifying the requirements of a "matched" condition for the irradiance monitoring device(s).
IEEE Journal of Photovoltaics
effective irradiance, effective temperature, I-V curve measurement matrix, performance model calibration, parameter fitting, single diode model, temperature coefficient.