Backtracking system sun angle assumptions

[Brian S]

Hi

When a tracking system is specified with backtracking - how is the sun angle approximated for each hour? Is it the average sun angle for that hour that's used to determine the backtracking angle? Also, what is the standard assumption for the backtracking angle on a cloudy day? Do the panels backtrack as normal or do they act differently?

Any further information on this would be appreciated.

Many thanks

[Brian S]

Further to this, it would be useful if you clarify the figure given for the backtracking angle within the hourly results. Example - if my module angle (Phi) at 7.00am is -2.0 degrees, is this the instantaneous angle at 7:00am or the average of the angles between 6:00 and 7:00?

Many thanks