Author Topic: Wind and solar - not always a good mix!  (Read 2726 times)

0 Members and 1 Guest are viewing this topic.

Offline rossw

  • Senior Moderator
  • Hero Member
  • *******
  • Posts: 878
  • Karma: +35/-0
  • Grumpy-old-Unix-Admin
Wind and solar - not always a good mix!
« on: January 13, 2012, 10:42:49 pm »
Well, after my post on making my solar trackers over here, it seems only fair to describe the problems (and cure) that came soon after.

We'd had weeks of continuous rain. The ground and everything in, on and around it, was soaking. Then we had a storm. Substantial wind gusts, but also very very turbulent - blowing from one direction, then in a moment it'd be blowing from a completely different direction. It did this for hours! Trees were pushed over all over the state.

Well, next sunny day the panels outputs were "odd". Something I couldn't put my finger on, so I went topside to have a look.
Then I came back and got my camera.





Looking down, you can see the great gaping hole around the concrete. These things were set in 3' deep, 12" diameter concrete. The soaked ground, followed by the buffeting wind had worked all the arrays loose in the ground and just spun them around like kids toys!


These two are actually "pointing" to the same place - north. At least, they THINK they are!


I considered a variety of remedies. None particularly appealed. In the end, I decided it had to be a dual effort. I had to try to stop the ground getting quite so wet, and I had to stop the thing flopping around in the hole. The panels had suffered no damage. The frame, tracking mechanism, head, actuator and even the post itself were all in perfect condition. No damage. It was purely that it was moving in the ground.

So... once the ground had dried out enough to work on, I cleared an area around the post, squared everything back up. Cut some diagonal struts to spread the load. Put some mesh in the hole and welded it to the legs. I also cleaned out around the hole, rammed it full of dirt, hard.


Then, mixed up concrete. Don't let this fool you. There's the equivalent of 8 bags of concrete in there!


The second one just did not want to come straight. I ended up needing my hand winch to pull it upright. I had to drive a 1.5" diameter steel spike 4 feet into the ground to hold it. Even then, the ground was still soft enough I pulled the spike sideways 6".


It got the same treatment.


My welding is utter crap. My excuse was that it was hot, I was working cramped, and it was galvanised steel!
Still, I did all 4 faces of each, I doubt they will fall off.



The last one. It was getting easier now. I thought.




The cat was so impressed, he decided to bring me a snack.

Offline wilfor03

  • Full Member
  • ***
  • Posts: 61
  • Karma: +2/-0
  • USA - Union Grove, Al
Re: Wind and solar - not always a good mix!
« Reply #1 on: January 14, 2012, 07:29:48 am »
hey RossW.....for some reason when I put mine (Tracker Pole) in the ground, I dug a 2' x 4' deep hole and made it a

solid platform from the 'git-go'. Don't know how I done it right the first time, but, still working (2 years). Sorry you had all that trouble.

Still a damn fine build.

Bill


Offline philb

  • Full Member
  • ***
  • Posts: 123
  • Karma: +6/-0
  • No Personal Text Set by User
Re: Wind and solar - not always a good mix!
« Reply #2 on: January 14, 2012, 10:27:19 am »
RossW, the soil conditions in your area are different than the ones in mine or anyone else's that's not in the immediate area. My soil is heavily laden with red clay. I knew your concrete scheme would not work in my area. 

I am still planning to copy your design because it simple and structurally stable. 

I have a clean slate to work with. If you should any have thoughts about automatic protection devices for solar or other items, I'd be interested.
 
My basic plan is to mount most of 4 KW solar panels on trackers. The must have 'core' panels will be solidly mounted on the house. I'm thinking about using some sort of sliding garage door arrangement for automatic protection against wind and hail. When bed weather comes, the door slides over the cells.

Thank you for posting the trackers and also your mistakes in this post.
Phil

Offline Tritium

  • Full Member
  • ***
  • Posts: 55
  • Karma: +4/-0
  • No Personal Text Set by User
Re: Wind and solar - not always a good mix!
« Reply #3 on: January 14, 2012, 03:31:48 pm »
Ross that is one good looking cat and proud too I bet.  :)

I bet that concrete "apron" helps keep the ground dry next to the poles to prevent any future incidents.

Thurmond

Offline rossw

  • Senior Moderator
  • Hero Member
  • *******
  • Posts: 878
  • Karma: +35/-0
  • Grumpy-old-Unix-Admin
Re: Wind and solar - not always a good mix!
« Reply #4 on: January 14, 2012, 04:43:28 pm »
Ross that is one good looking cat and proud too I bet.  :)

Yeah, he brings a rabbit home most days. Two on a good day.
And yes, we DO feed him. Breakfast, lunch and dinner. But he still has to bring home "snacks". I just wish he wouldn't eat them on the front doorstep!

Quote
I bet that concrete "apron" helps keep the ground dry next to the poles to prevent any future incidents.

The reasoning was several-fold.
Firstly yes, to help keep the area around the post dry.
Secondly (and the diagonal struts are critical in this) - if the post tries to move one way, it has the dual battle of trying to LIFT the slab on one side, while simultaneously pushing the slab into the ground on the other.

I've seen no sign of even a slight movement even during very strong, buffeting winds since the modification.

Offline artv

  • Jr. Member
  • **
  • Posts: 47
  • Karma: +1/-1
  • No Personal Text Set by User
Re: Wind and solar - not always a good mix!
« Reply #5 on: January 15, 2012, 06:36:38 am »
Hi Ross,
Not sure how long it's been since your modification,but I would suggest you dig a trench around the two sides and the high side of the hill ,around your slab, about 2' deep ,put some big o in the trench ,then fill with sand ,and extend the big o, about 3-5' down the hill off the sides.
I have worked on cottages ,that were on similar slabs on hill sides, over time the whole slab tends to "roll " down the hill from the continued flow of ground water after every rain.
Too late ,but anybody pouring a slab on grade, you should put a layer of styro-foam underneath ,this will prevent the concrete from cracking.
Might be alright the way it is ,but the big o won't hurt.
Hope it works o.k for you.......artv

Offline bj

  • Hero Member
  • *****
  • Posts: 728
  • Karma: +23/-0
  • Lamont, Alberta, Canada
Re: Wind and solar - not always a good mix!
« Reply #6 on: January 15, 2012, 07:14:13 am »
   I'm a big fan of big O and styro as well Art.  But then, I used to get styro at Dow's cost.  Alas, no more.
But then not everyone has our frost problems.  (Canukistanian thing)
"Even a blind squirrel will find an acorn once in a while"
bj

Offline artv

  • Jr. Member
  • **
  • Posts: 47
  • Karma: +1/-1
  • No Personal Text Set by User
Re: Wind and solar - not always a good mix!
« Reply #7 on: January 15, 2012, 05:09:15 pm »
Hey bj ,
A good place to get good deals on styro-foam is flat roofing co's,
Alot of the time when they do strip off's ,they keep the old and will sell it dirt cheap..
It does'nt matter if it's pieces ,just fill the cracks with expandable foam ~12 bucks a can,..goes along way...the best thing you can put under any kind of slab..

btw;glad to hear you "got it" and again thank-you.....Art