Incidence-angle dependent external quantum efficiency: Laboratory characterization and use in irradiance-to-power modeling

We propose and analyze the use of an angle-of-incidence (AOI)-dependent external quantum efficiency (EQE) as the basis for a more accurate representation of specular reflection and diffuse light utilization in PV system modeling. We derive a response function defined by the ratio of the EQE spectrum at a given incidence angle to that at normal incidence as a replacement for the f2 and fd parameters in the Sandia Array Performance Model (SAPM). The response function can be obtained from measurements readily made in the laboratory, providing a rapid, versatile method for more accurately calibrating module performance models.