IAM factor applied to diffuse and albedo components

[SE2015]

Hi,

I have a question regarding the IAM factor: the help files mention that during the simulation it is applied to the diffuse component and the albedo component separately. Can you explain the different application? The help files are a bit vague about it.

Thanks

[André Mermoud]

For the calculation of the IAM loss for diffuse, we suppose that the diffuse component is isotropic, i.e. has an equivalent value for any direction of the space.

PVsyst performs an integral of the IAM loss for all directions "seen" by the collectors. This IAM factor doesn't depend on the sun position, it is only dependent on the system geometry, and is constant over the year.

This factor is applied to the diffuse component at each hourly step of the simulation.

The factor on albedo is treated in the same way, as an integral of the IAM for directions at ground level.

[snag1]

When running a simulation should I use the user defined Incidence angle profile supplied by model manufacturer or should I use default ashrey model. I noticed that generation is much higher when using user defined values. Tried searching for information on this forum, but could not find anything. Any help would be most welcome. Thanks is advance.

[André Mermoud]

If you trust the manufacturer's parameters you can use them.

The IAM measurements are very difficult.

Please see our FAQ How to determine the IAM profile ?