Determination of Empirical Coefficients and ΔT for Sandia Thermal Model: Dependence on Backsheet Type

Sandia thermal model has been extensively used by the industry to predict cell temperature of photovoltaic (PV) module using a few empirical coefficients and AT (temperature difference between cell and typical backsheet). We present the empirical coefficients and AT of the PV modules equipped with various types of new polymer backsheets and glass substrate. These backsheet-specific coefficients and AT provide more accurate predicted cell temperature. It was shown that AT can be as high as 4.1°C at 1000 W/m
²
irradiance depending on the substrate type. It has been demonstrated that the temperature coefficients, using model converted cell temperature from module substrate temperature, can be overestimated when non-thermal equilibrium condition is existing in the PV module.