[RE-wrenches] Tracker effectiveness

[William Miller]

Friends:

For years I have relied on some old studies to quantify the effectiveness 
of one and two axis tracking.  I have heard anecdotal reports that tracking 
does not deliver the increase in power that was originally reported, 
especially in winter.  Are there any recent studies on PV tracking that 
might quantify these values?  I would like to compare tracking in off-grid 
and grid-tie applications.

Thanks in advance.

William Miller