<html>
<body>
It appears that <u>typically</u> no solar PV tracking system is
economically worthwhile. This arises because you can install
additional fixed-tilt solar PV modules to equal the same amount of annual
energy as the tracking system provides, yet the additional modules cost
less than the tracking system's costs.<br><br>
This has been apparent for several years, and with the significant drop
in PV module pricing the difference is even greater today.<br><br>
There may be applications where a single-axis tracker is indeed
worthwhile, if it is designed and constructed in a very simple manner,
such as in an off-grid system.<br><br>
I'd be interested in readers' comments on their own experience.<br><br>
+Gordon Howell<br>
Edmonton<br><br>
<br><br>
<br>
Date: Sat, 30 Jul 2011 09:57:35 -0400<br>
<blockquote type=cite class=cite cite="">From: Frank Tettemer
<frank@livingsol.com><br><br>
/Just for reference: normally on single-axis tracking collector systems,
<br>
the axis is E-W, not N-S. Are you CERTAIN it's N-S? Also, single-axis is
<br>
generally good for more like 20% performance improvement, not 30-40%.
<br>
But at those far north latitudes it may be that my rules of thumb suck
<br>
(terrible pun on thumb-sucking, for those who missed it).<br><br>
K/<br>
............................................................................................................<br>
I agree with Derek and Kieth that these trackers, at best, will improve
<br>
productivity, by (perhaps) 30%. However, for a gambling man, this
means <br>
their added initial cost will pay off the installation costs about as
<br>
quick or quicker than the fixed mounts. The carrot to this is that
<br>
after the installation is paid off, the daily production is greater and
<br>
thus the owner's income per month is also greater.<br><br>
Yes, I've seen quite a few of these North-Southhorizontal pole mount
<br>
trackers. They've become quite common trackers in the Ottawa
Valley, <br>
Ontario. Talking to an installer/purveyor of these devices from <br>
Pembroke, and he says they cost 50% less than a Dager tracker, which
<br>
seems to be the other common microFIT tracker in this rural
area.<br><br>
The Dager tracker is a single pole mount, holding 10kw, mounted on a
<br>
monstrous concrete base, and the actuators are two axis tracking, thus
<br>
keeping the PV's at 90 degrees to the sun shine from early AM to late
<br>
PM. They are definitely the most productive of the tracking devices,
<br>
compared to the North-South horizontal pipe mounted thingies.<br><br>
My wife and I have built and installed our own microFIT, using eight
<br>
steel poles, no tracker. These mounts can be adjusted seasonally, to
<br>
optimize production but definitely have a production curve that begins
<br>
low in the morning, goes to full production mid-day and drops off in
<br>
afternoon.<br>
What we've done is mount 13,000 watts of PV's, to sell 10,000 <br>
watts/hours. As Derek has talked about, we've spent our money on
more <br>
fixed mounted PV's, to get a greater daily yield, without the <br>
difficulties of maintenance of a tracking device.<br><br>
Two Reasons being: I've seen one of these North-South horizontal
pole <br>
mounts tipped to the East, and stuck there, for a full month, because
<br>
the installer was too busy installing more of them to come back and fix
<br>
the broken one. This was a turn-off.<br><br>
And secondly, a Dager tracker holds 10Kw on one pole. That is One Huge
<br>
Sail. The one I'm aware of in Southern Ontario was blown over in a
huge <br>
wind, and I'm told it wasn't a pretty site. (PV's contain very large
<br>
sheets of glass.) Yes, they broke. And how did they re-erect that
huge <br>
tracker?<br><br>
I like the simplicity of a fixed mount, where I can go out four times a
<br>
year, with a pair of wrenches, and manually adjust my mounts. It
adds , <br>
maybe, eight total hours of labour per year. I can do that.<br><br>
Frank<br><br>
Frank Tettemer<br>
Living Sol ~ Building and Design<br>
<a href="http://www.livingsol.com/" eudora="autourl">www.livingsol.com</a>
<br>
613 756 3884</blockquote></body>
</html>