[Medium] How much difference is there between irradiance transposition models?

[kandersolar]

The irradiance hitting a tilted PV module (the plane-of-array, POA, irradiance) can be estimated using an irradiance transposition model. pvlib-python includes several transposition models developed by the solar PV research community, including common ones like Perez and Hay-Davies, and less common ones as well. Here is a listing of the transposition functions available in pvlib: https://pvlib-python.readthedocs.io/en/stable/reference/irradiance/transposition.html

Different transposition models produce different estimates of POA irradiance. How much variation is there between model predictions for the same weather inputs?

You can use one of the weather files in the data folder, or some other weather file or clear-sky simulation of your choice.

Helpful links:

• https://pvlib-python.readthedocs.io/en/stable/reference/generated/pvlib.irradiance.get_total_irradiance.html
• https://pvlib-python.readthedocs.io/en/stable/gallery/irradiance-transposition/plot_transposition_gain.html
• https://pvlib-python.readthedocs.io/en/stable/gallery/irradiance-transposition/plot_ghi_transposition.html