Potential Problem with Resource Azimuth

While running a CSP model (steam or molten salt, doesn't seem to matter which), I noticed that some sites have what seems to me to be an odd artifact with respect to the solar azimuth. I am using the built in locations on the SAM program. For example, if you use India (Trivandrum) and plot the time series, the resource solar azimuth really spikes in March - it almost looks like the data is inverted. I am not seeing this with every location, but I randomly clicked around and noticed the same artifact with Sri Lanka (Kankesanturai) and UAE (Abu Dhabi) - there probably are a few more. I attached a picture to illustrate. Any idea what I might be seeing here? Thanks!

Hello,

This pattern seems to be present in CSP azimuth calculations for latitudes between about 7 and 13 degrees N. I'm not sure what is causing it, but am having the CSP team look into it, and will follow up when I learn more.

Best regards,
Paul.

Great, thank you Paul - much appreciated!

Paul, just wondering if the CSP team had made any headway onto the azimuth question. Thanks again for your help.

Hello,

It turns out that those odd-looking sun azimuth angle values are for night-time hours when the model does not use the values and do not affect the simulation results. You can see that in the time series graph if you zoom in to a day or two in March.

(The photovoltaic model sets the night-time sun angle values to -999 as a flag indicating the values are not valid.)

Best regards,
Paul.