Solar tracker in windy Colorado

[Chuck]

The photo below shows a Zomeworks tracker I set up a year and a half ago on the plains of northeastern Colorado. The building (barn) is due north of the tracker due to my paranoia about the prevailing north winds. It is common for this part of the country to get 80 mph winds several times a year, usually coming straight out of the north or northwest. As you can see, there are no trees to block north winds here. In deference to this fact, I purposely left two of the panels off the tracker, so as to reduce the wind load. The pole is six inch diameter steel pipe sunk 5' into a concrete base.

 



Zomeworks is pretty unique in that it uses a freon based passive system for tracking the sun. I was skeptical, but it works well as long as the sun is bright and the wind isn't pushing on it too hard. If the wind is from the north it wiggles a bit but still tracks the sun due to being in the wind shadow of the barn. A strong west wind will push it to face the east (and vice versa). A south wind seems to accentuate the tracking and push it too far the right direction. In either case it reduces the power feed from the tracker panels.


This picture is old and doesn't show the eight additional PV panels now mounted on the roof of the barn. While the tracker doesn't shade the panels, I hope to shorten the mounting pipe by a couple feet sometime. Hopefully this will reduce the tracker's westerly wind resistance and allow me to make use of the lower part of the roof for more stationary panels.

[deloiter]

For those interested in building a freon based solar tracker, here is a link to a DIY solar tracker project from Mother Earth News.  http://www.motherearthnews.com/library/1977_November_December/Mother_s_Super_Simple_Solar_Tracker

[Titantornado]

I imagine that propane would also work on that setup, and would be easier/cheaper to acquire.

[Shadow]

Nice setup! How many watts? And what all do you power with it?

[georgeodjungle]

ya ya nice:

and high up out of the snow.

[Phil Timmons]

Hey Chuck,

We put up four of these (at one location) late last year.

Our total sq.ft. per tracker was about 15' X 15' = 225 sqft.  Puts out about 1600 watts, each.

So our entire mounting surface was used, up both sides and on the middle, too.

The location is in Westish (not quite full West ) Texas.  So they get some big wind loads, also.  Their poles were 8" Schedule 80, 12 feet into the ground, in reinforced concrete.  I still think a tornado will pick them up and toss them like a frisbee -- but they only hired me for the electrical end, not the mechanical.

I did help the installer, thought, and we put a pair of HUGE one way shock absorber pistons on each of them that really do seem to dampen the wind shocks.  The site is VERY windy -- it overlooks a large valley -- and we do notice that as some seem to shelther, or wind shadow each other, depending on the wind direction, they do not all seem to track exactly together on windy days.  Smart idea for you to put it in the wind shadow of the barn.

We put the array together on scaffolds on the ground, and used a crane to drop them on the poles.  Did you build yours on the ground, or up in the air?  It looks like you put yours up pretty high, about the same as we did.  I think it is something like 6 to 8 feet to the ground from the low point, on ours, when it is fully tilted over.  So you think if they were closer to the ground it would reduce the windload?  Dunno, either way, but we have chatted it a bit, too.  I guess George makes a good point for you needing to keep yours up out of the snow.

[Chuck]

There is currently 800 watts on it. If I put the other two panels on it I could get a kw out of it, at least the rating would be a kw. With the panels (another 800 watts) on the roof I get about 1400 watts on a clear day around noon. The main thing the tracker does is increase the peak output time by several hours.

I'm currently building a home on the site, so the power is going to power tools and a refrigerator in a trailer. Some lights and an internet connection occasionally.

Chuck

[Chuck]

Contrary to popular opinion, not all of Colorado gets lots of snow. We haven't seen over a few inches in these parts for years. There used to be a lot more when I was a kid in the next county over (and closer to the mountains), but that was long ago... <sigh>

[Chuck]

Oh man, those are monsters. About twice the capacity of mine. I used a six inch pipe and the pivot is at 10 ft above the ground. I think the dimensions are about 10'x10', but I could be wrong. The lowest point ends up being about 4 feet off the ground when tilted at winter setting. The shock absorbers are pretty big and take a long hard pull to get any movement.

Yes, I assembled it on the ground and lifted it up with a makeshift crane assembly, but I didn't put the panels on until it was on the pipe.

It's interesting you put those up in Texas. One of the things the sales guy mentioned is that they use them in Texas and since the wind is nasty there, we should be OK here. I grew up with 120 mph winds close to the mountains and I know we get 80+ mph out here. It still spooks me, but so far it's survived.

Chuck