pvl_iam_physical

Determine the incidence angle modifier using the "physical" model.

Contents

Syntax

Description

pvl_iam_physical calculates the incidence angle modifier using the physical model [1] which is based upon Snell's Law for transmission of light and and Bougher's Law for absorbtion within a cover. Required information includes incident angle, cover extinction coefficient, cover thickness

Note: Eqn. 14 in [1] is incorrect. The correct equation (implemented in this function) is:

$$\theta_r = \arcsin \left( {frac {\sin\left(\theta\right)} {n}} \right) $$.

Inputs

Output

Example

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

K=4;             %glazing extinction coefficient in units of 1/meters
L=0.02;          %glazing thickness in units of meters
n= 1.56;         %index of refraction
theta = 0:90;    %incident angle in degrees
IAM = pvl_iam_physical(K, L, n, theta);
figure
plot(theta,IAM)
xlabel('Incident Angle (deg)')
ylabel('IAM')
title('Physical IAM Model Example')

References

[1] De Soto, W., Klein, S. A., Beckman, W. A., 2006. Improvement and validation of a model for photovoltaic array performance, Solar Energy, vol 80, pp. 78-88.

[2] Duffie, John A. & Beckman, William A., 2006. Solar Engineering of Thermal Processes, third edition. Available from http://common.books24x7.com/toc.aspx?bookid=17160.

See also

pvl_getaoi , pvl_ephemeris , pvl_spa , pvl_iam_ashrae , pvl_iam_martinruiz

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