pvl_ashraeiam

Determine the incidence angle modifier using the ASHRAE transmission model.

Contents

Syntax

Description:

Calculates the incidence angle modifier as developed in [1], and adopted by ASHRAE (American Society of Heating, Refrigeration, and Air Conditioning Engineers) [2]. The model is used by modeling applications such as PVSyst [3].

Note: For incident angles near 90 degrees, the ASHRAE model has a discontinuity which has been addressed in this function.

Inputs:

Outputs:

Example

This example plots the IAM over a range of incident angles.

b=0.05; %Typical value.
theta = 0:89.9;    %angles =>90 generate a warning
IAM = pvl_ashraeiam(b, theta);
figure
plot(theta,IAM)
xlabel('Incident Angle (deg)')
ylabel('IAM')
title('ASHRAE IAM Model Example')
Warning: It seems that we have encountered a discontinuity in pvl_ashraeiam. Any
incident angle modifiers calculated to be less than 0 or greather than 1 have
been set to 0. 

Note that the function can result in IAM values <0 and/or >1. When this occurs the out of range results are set to equal zero and a warning is reported.

References:

See also

pvl_getaoi , pvl_ephemeris , pvl_spa , pvl_physicaliam

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