Question about solar calculation script


Dear Ninja community,

I am a student learning about energy modeling studies. I found your scripts on Github used to calculate solar PV capacity factor and solar powers. That are excellent works and I really appreciate that you share these codes.

I have some minor questions regarding these codes and hope I can get some information from you. I am trying to calculate the solar capacity factor using your code with the one-axis tracking system. In the code, the incidence angle is calculated as:

(1) when tilt = 0: incidence angle = np.arccos(np.sqrt(1 - np.cos(sun_alt) ** 2 * np.cos(sun_azimuth - azimuth) ** 2))

For my understanding, the 1-axis tracking would allow the solar panel ideally have an incidence angle with the sun the same to the solar_altitude. And the incidence angle = np.arccos(np.sin(sun_alt)). Is that correct? It seems to me that the original calculation is kind of the same to the fixed-axis system with tilt is zero?

(2) If I am correct, when tile > 0, the incidence angle between the sun and solar panels would be (tile+solar_altitude)?

(3) Also, I am not sure why you calculate the panel tilt (tilt single tracking) under the 1-axis tracing calculations?

I would appreciate any response from you! Thanks very much!