Allan,
Thanks for the update. I will be open to specifying trackers again,
at least for grid tied systems. I appreciate the quantification of
the costs and efficiencies.
Drake
At 01:55 AM 4/14/2009, you wrote:
-----Original Message-----
It is great to hear that Wrenches are having better luck with
trackers. This recent thread, on the subject, is way different that
what has been stated in the past. It sounds like trackers might
really be a cost effective approach to net metering. Is it really
more cost effective than adding more modules, as we had figured in the past?
Drake
Drake,
Yes it is, clearly, if the homeowner has the unobstructed space to take
advantage of the long summer sun path. It won't help much in a forested site
with a narrow south solar window.
The logic about adding more modules is a holdover from the off-grid days. A
tracker adds 35-40% more output in summer and ~15% in winter. Off-grid needs
to maximize winter gain when tracking provides the least benefit. Grid tie
allows all of that summer gain to be harvested, provided that the utility's
true-up is annual and not monthly.
Our rule of thumb: tracking adds about 15-20% to overall system cost, and
adds 30-35% to annual production in our region. We install quite a few, all
Wattsun.
Allan at PosE
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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
740-448-7328
740-856-9648
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