Tubular towers and PV mounting [RE-wrenches]

[Ian Woofenden, Home Power]

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Thanks for your comments and explanation, Tom. I don't even pretend 
to understand engineering (I know how to spell it, so I can do my 
job), and certainly we won't do anything custom without having an 
engineer involved.

I agree on the aesthetics of three-legged towers. I was on Randy 
Brooks' crew for the installation of one last May and I fell in love. 
It was painted green and blended into the forest. But de gustibus non 
disputandem est (there's no accounting for tastes), so we have to do 
the research on what the customer wants. If it's impractical or 
prohibitively expensive to do a monopole, that will be fine by me.

A local company makes tubular towers for utility-scale wind turbines. 
I'll be talking with them about this project too, in case they want 
to play with the little guys.

Regards,

Ian

>  Ian,
>
>    The customer can't see the beauty of a triangulated structure? Too bad..I
>just set a 120' high three legged freestanding tower last week (local
>emergency services antenna site) and while I was only operating the crane,
>the guys uptower made quick work of the installation, I didn't catch the
>brand name of the tower but it was beautifull! I just wanted to see a wind
>turbine up there instead of police antennas. Visually, a tubular tower would
>have more impact then a three legged in my opinion.
>   If the PV array is to of any significant size, wind side load on the tower
>could be a major factor on the tower stability in high winds. If pushed out
>of column the tower would lose much of its compressive strength, this is
>best illustrated by standing on an empty beer can, carefully done an
>undented can will support your weight, a very small ding in the can will
>result in structural failure. Or, by pushing the ends of a soda straw
>together, while straight it exhibits high compressive strength, a little
>curve and it fails. Further, the side load of the wind turbine could be
>opposite or at an angle to the side load of the PV array (in a very strong
>east wind for instance), this could set up all kinds of interesting
>aerodynamic flutter situations as the air spills over the PV array, this
>could all be designed for of course, and it will sure make the tower company
>design engineer earn his pay!
>   I have found my local billboard/sign company to be a wealth of information
>for getting a handle on the dynamics of a mono-pole structure, they do it
>all the time, and don't have the luxury of doing it in remote places, they
>do it in busy parking lots etc. where any failure will make major news!
>
>Tom Simko
>Skyline Solar
>
>
>
>
>
>
>on 11/14/03 10:22 PM, Ian Woofenden, Home Power at
>ian.woofenden at homepower.com wrote:
>
>>
>>  Greetings Wrenches,
>>
>>  Kelly Keilwitz of Whidbey Sun & Wind and I are planning for a project
>>  that will be the installations for both the SEI PV and wind workshops
>>  here next October. We're looking at a 140 to 160 foot tower with a
>>  12-15 foot diameter wind turbine and 2 to 3 KW of PV mounted at 60 to
>>  90 feet up the tower.
>>
>>  The customer is interested in a tubular tower for aesthetic reasons.
>>  I have no experience with these, and prefer the idea of a
>>  three-legged freestanding tower like the Rohn SSV, both for mounting
>>  PVs on and for climbing. On the other hand, I'm always up for a new
>>  adventure, so I need to find out if a tubular tower is practical for
>>  this project.
>>
>>  Do any of you have experience with:
>>  * Tall tubular towers
>>  * Putting PVs on tubular towers
>>
>>  Please share your experience, recommendations, warnings, hopes, and dreams.
>>  ;-)
>>
>>  Thanks,
>>
>>  Ian
>>
>
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-- 

Ian Woofenden <ian.woofenden at homepower.com>, Senior Editor
Home Power magazine, The Hands-On Journal Of Home-Made Power
My use of words is just some antics.

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