PV Module Operating Temperature: Reliable Extraction of Model Parameters from Dynamic Field Data

Module temperature is widely perceived to be a secondary and much less significant factor than irradiance for determining PV system yield. This is understandable to the extent that irradiance is the fuel and temperature merely affects the conversion efficiency of that fuel; however, the uncertainty in module temperature and uncertainty in irradiance can make similar contributions to uncertainty in yield. Thus, accurate models for PV module operating temperature and accurate parameters for those models are essential for accurate yield assessments. In this work we develop and demonstrate an effective strategy to account for the effects of thermal mass in both parameter extraction and system simulation processes. This strategy can be used with a variety of empirical steady-state equations, but the best results are achieved when the steady-state equation accounts for radiative losses to the sky. We therefore propose a new model to accompany the fitting strategy—one that sacrifices a little bit of the simplicity of industry-standard models to achieve substantial gains in modelling accuracy.