pvlib.iam.martin_ruiz#
- pvlib.iam.martin_ruiz(aoi, a_r=0.16)[source]#
Determine the incidence angle modifier (IAM) using the Martin and Ruiz incident angle model.
- Parameters:
aoi (numeric, degrees) – The angle of incidence between the module normal vector and the sun-beam vector in degrees.
a_r (numeric) – The angular losses coefficient described in equation 3 of [1]. This is an empirical dimensionless parameter. Values of
a_rare generally on the order of 0.08 to 0.25 for flat-plate PV modules.
- Returns:
iam (numeric) – The incident angle modifier(s)
Notes
martin_ruiz calculates the incidence angle modifier (IAM) as described in [1]. The information required is the incident angle (AOI) and the angular losses coefficient (a_r). Note that [1] has a corrigendum [2] which clarifies a mix-up of ‘alpha’s and ‘a’s in the former.
The incident angle modifier is defined as
\[IAM = \frac{1 - \exp(-\frac{\cos(aoi)}{a_r})} {1 - \exp(\frac{-1}{a_r})}\]which is presented as \(AL(\alpha) = 1 - IAM\) in equation 4 of [1], with \(\alpha\) representing the angle of incidence AOI. Thus IAM = 1 at AOI = 0°, and IAM = 0 at AOI = 90°. This equation is only valid for 0° <= aoi <= 90°, therefore iam is constrained to 0.0 outside this interval.
References
