This routine computes losses due to spectral response at the module level. This model uses the air mass coefficients computed by Sandia, and is referred to as the f1 (AMa) function in the Array Performance Model. The model is based on an empirically determined polynomial relating the solar spectral influence on the short circuit current to air mass variation over the day.
King, D. L., Kratochvil, J.A., Boyson, W.E., Measuring Solar Spectral and Angle-of-Incidence Effects on Photovoltaic Modules and Solar Irradiance Sensors. Sandia National Laboratories, Albuquerque, NM, September 1997.
King, D. L., Boyson, W.E., Kratochvil, J.A., Photovoltaic Array Performance Model. Sandia National Laboratories, Albuquerque, NM, December 2004.