Sandia IAM

This model computes the incidence angle modifier coefficients based on the Sandia method.






Sandia IAM Algo75
Only the beam component ΘEff,D is treated here. Furthermore, it was observed that the best fit of the IAM coefficients for both FSLR anti-reflective coating (ARC) and regular non-ARC modules shows an oscillation below incidence angles of 34°, as shown in Figure 32.

Sandia IAM Figure 15-1
Sandia IAM Figure 15-2

Figure 32. Comparison of Custom IAM Profile with Sandia Polynomial, Showing Oscillation for Incidence Angles Lower than 34°



To avoid this artifact, the polynomial is clipped to force the IAM to unity, as follows:

Sandia IAM Algo 76


King, D. L., Kratochvil, J.A., Boyson, W.L., Measuring Solar Spectral and Angle-of-Incidence Effects on Photovoltaic Modules and Solar Irradiance Sensors. Sandia National Laboratories, Albuquerque, NM, September 1997.