[RE-wrenches] Tracker effectiveness

[Jeff Clearwater]

Hi William,

We've been running 2 different tracker-mounted 12 KW (DC) systems in 
Corona, CA.

System #1:  Horizontal-axis (N-S axis) installed Sept of '02.  So we 
have 6 years of data on that.

System #2:  Dual-Axis Wattsun Trackers:  Installed April of '04. So 
4.5 years of data on that.

The NREL numbers predicted a 40% increase over fixed-at-latitude for 
the dual axis and 29% for the horizontal axis.

Although I have not compiled the data for a while I do remember when 
checking after a full 2 years on each that the numbers were very 
close to matching those predictions.  Only under by a few percent if 
at all.

Both systems feed into a Sunny Boy Control Plus with a dedicated 
modem so I can call up the system anytime and we have inverter by 
inverter data for the whole 24 KW array.  If you'd like that data I 
can send it to you.  Contact me offlist.

Best,

Jeff C.






>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
>
>
>
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-- 
~~~~~~~~~~~~~
Jeff Clearwater
Senior Design Engineer
NABCEP (tm) Certified Solar PV Installer
http://www.nabcep.org/
NorthEast Solar Design
Turnkey Solar Design & Installation for the Commercial Sector
http://www.villagepower.com
gosolar at villagepower.com

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