Concentrating PV - irradiance and output drop at solar noon???

Hi all,

When running SAM with an X-concentrated PV cell array, I get this crazy behavior every day at solar noon. The Plane-of-Axis (POS) drops to zero W/m2, and thus kWh production does the same. It's almost as if there is a shadow cast over the tracking cell at precisely solar noon. (please see screenshot below).

Can anyone explain why this is happening, and how to get rid of it to accurately model daily output?

Many thanks!

J

Is there a limit on the tracker so it can't reach the desired
position at solar noon?

See Array - Tracker - Tracker elevation/azimuth angle limit

I agree with solarjoe that the tracker limit is the likely culprit. Note that the noontime "dip" in plane-of-array irradiance happens around the summer solstice (June 21), when the solar zenith angle at noon is at its annual lowest. That is when the default tracker elevation angle limit of 15 degrees comes into play. If you change the "Tracker elevation angle limits" minimum value from 15 degrees to zero, the dip should disappear.

Best regards,
Paul.

Thank you SolarJoe and Paul Gilman!!! It was indeed the elevation angle ("tilt"), which wasn't getting flat enough to catch the mid-summer mid-day sun. Setting the minimum to 0 resulted in the standard output curve. Many thanks to you guys and the forum!!!