pole mount foundation

ws9876

If you wanted to do a 6 inch steel pole(single pole) mount for 3 -250 watt panels about 4 ft off the ground when installed............
how deep and wide should the sonotube be in the ground???should it have a footing,how big??? 
or would a J bolt set up be better and a pole mounted above ground to a bracket that attaches to the J bolts??like wind turbines...

vtmaps

The size and depth of a pole mount foundation depends on the soils.  There are a couple of articles in Home Power that you can download. I provided links to the articles in this thread:   http://forum.solar-electric.com/discussion/14834

--vtMaps

mike95490

you don't want a sonotube way down in the ground, unless it's so sandy the hole would cave in.  You want a rough lump of concrete so that it won't "rotate" in the hole.

vtmaps

mike95490 said:

you don't want a sonotube way down in the ground, unless it's so sandy the hole would cave in.  You want a rough lump of concrete so that it won't "rotate" in the hole.

My pole mount foundation is a 5 ft deep, 24" diameter sonotube.  It sits on a square footing.  It will not rotate.  If I had tried to pour without a sonotube I would probably have needed twice as much concrete.  28 bags of sackrete is not something I would want to double.

Speaking of rotation, it is very important to make sure the pole can't rotate inside the concrete.  I drilled a couple of holes in the steel pole and put a couple of pieces of 3/4" rebar sticking out of the pole into the concrete.

--vtMaps

Ethan Brush

In freezing climates, you typically want the concrete below the frost line, and something with smooth vertical sides so the frost cant "grab" it.  For my climate here, and for the setup you propose, I would do a 12 inch sonatube 5 feet down.

ws9876

btw  did you wait till the footing dried to fill the sonotube??

vtmaps

ws9876 said:

btw  did you wait till the footing dried to fill the sonotube??

Yes, but only a few hours.  I poured the footing in the morning, and the sonotube after lunch.   Make sure to have a few pieces of rebar sticking up out of the footing into the sonotube.

Ethan Brush said:

In freezing climates, you typically want the concrete below the frost line, and something with smooth vertical sides so the frost cant "grab" it.  For my climate here, and for the setup you propose, I would do a 12 inch sonatube 5 feet down.

Very good point about the freezing... I forgot to mention that.    I'm no concrete engineer, but my instinct tells me that a 12" sonotube is too small for a 6" steel pipe.... that only gives a 3" shell of concrete around the pipe.

--vtMaps

Mountain Don

Is there an automatic spam system in place with this software. I tried to post a message that contained links to a website that has pole foundation information. When I click the Post Comment button the message disappears.....

The link was to DPW Solar. They have an online calculator where panel size, number of panels, height, winds, snow loads are all entered. It then provides a diagram of results.  Note that the minimum diameter of the concrete is 30 inches. 

Mountain Don

That worked w/o the link.  Let's try the link again....

http://configure.dpwsolar.com/user/login.html?referrer=/

You need to register but is is free.  Handy tool IMO

BB.

Mountain Don, yours is one of the posts (or several) that are stuck in the Spam system... Hopefully it (and others) will be marked "not spam" today when the Vanilla support person takes a look.

I am not used to how spam control works here--The old forum software did not have any content related spam queues.

-Bill "moderator" B.

Mountain Don

Cool.  I mean that, as someone who has fought spammers for years.  Perhaps there is a limit to the number of links permitted per post??

BB.

It is all new to me in this forum software. I would turn Spam filter for posters with more than a few initial posts.

At this point, the software does not appear to notify me when stuff is in the Spam Queue--And the way it listed spam was confusing too.

-Bill

Dave Angelini

ws9876 said:

If you wanted to do a 6 inch steel pole(single pole) mount for 3 -250 watt panels about 4 ft off the ground when installed............
how deep and wide should the sonotube be in the ground???should it have a footing,how big??? 
or would a J bolt set up be better and a pole mounted above ground to a bracket that attaches to the J bolts??like wind turbines...

Plan ahead my friend, a six inch schedule 40 pole can carry 125 square feet of panels under snow / wind load.
You might as well build a foundation to support it.

Mountain Don

DPW Solar has an online calculator for pole mount foundations. You do need to register to use it. data for the panel make / model and number of panels is entered. Wind, soil type, height above ground, snow load, etc are all entered. Then it comes up with a dimensioned drawing.  

Link to the calculator page.    If that does not work try THIS LINK and scroll to page bottom and look for link on left side. 

Note that their minimum recommended hole diameter is 30 inches. Any of these being installed to meet codes in the USA has to be designed for a minimum wind speed of 90 mph, just like habitable buildings. Panels on top of a pole will generate some very high forces when hit by high winds. Think of the worst case scenario and keep your equipment attached to your pole and in your yard, nit the neighbor's.  

Mountain Don

I tried this post once and something made it disappear. Hope I don't duplicate.

DPW Solar has an online calculator, HERE. If that does not work go here and find the link on the left near page bottom. 

You enter data; panel make / model, number of panels, height above ground, wind, snow load, etc. It provides a diagram with dimensions; depth, etc.  Note that the minimum hole / concrete diameter is 30 inches and that minimum wind speed to be used when installing to codes in the USA is 90 mph.  It takes a lot of concrete to ensure it won't tilt or end up in somebody else's yard. 

Mountain Don

DPW Solar has an online calculator for pole mount foundations. You do need to register to use it. data for the panel make / model and number of panels is entered. Wind, soil type, height above ground, snow load, etc are all entered. Then it comes up with a dimensioned drawing.  

Link to the calculator page.    If that does not work try THIS LINK and scroll to page bottom and look for link on left side. 

Note that their minimum recommended hole diameter is 30 inches. Any of these being installed to meet codes in the USA has to be designed for a minimum wind speed of 90 mph, just like habitable buildings. Panels on top of a pole will generate some very high forces when hit by high winds. Think of the worst case scenario and keep your equipment attached to your pole and in your yard, nit the neighbor's.  

Mountain Don

I tried this post once and something made it disappear. Hope I don't duplicate.

DPW Solar has an online calculator, HERE. If that does not work go here and find the link on the left near page bottom. 

You enter data; panel make / model, number of panels, height above ground, wind, snow load, etc. It provides a diagram with dimensions; depth, etc.  Note that the minimum hole / concrete diameter is 30 inches and that minimum wind speed to be used when installing to codes in the USA is 90 mph.  It takes a lot of concrete to ensure it won't tilt or end up in somebody else's yard.