Tubular towers and PV mounting [RE-wrenches]

[Tom Simko]

 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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