Wind-Loading question for the Pros

[Xringer]

Falling trees is a concern. I've been thinking about a crash-bar across the top.

However, I had the 10.5 foot mesh dish there since the early 80s and it hardly got a ding..

The only real damage to the structure was from ice expansion inside
a few of curved support arms. They were hollow and held water..

[aerohead]

Originally Posted by chaster

Good points. The question in my mind is the magnitude of the interference drag..

Eric,if you'll go up to the search-engine,top-left of forum page,type in FLOW-IMAGES(brain food) and go to Photo Gallery-7,second row,2nd image from right.
There is a depiction of a flat plate and the magnitude of the separation and wake area.
Your panels,even if spaced at large distance to one another would still be 'inside' the wake of adjacent panels.
I'm no pro.I have done professional installs with an area photovoltaic business.They always gang the panels together onto the smallest footprint,for fixed arrays,and also tracking mounts.Nearly every home where I live has PV and we all go for the minimums with respect to spacing.
Keeping the load concentrated near the center reduces what otherwise could grow to enormous torque,as loads are applied along very long moment arms.

[chaster]

Originally Posted by aerohead

Eric,if you'll go up to the search-engine,top-left of forum page,type in FLOW-IMAGES(brain food) and go to Photo Gallery-7,second row,2nd image from right.
There is a depiction of a flat plate and the magnitude of the separation and wake area.
Your panels,even if spaced at large distance to one another would still be 'inside' the wake of adjacent panels.

I wasn't doubting that there would be interference effects. I was just wondering what the *magnitude* of those interference effects would be.

I agree with your predictions of torque load on a single pole mount.

Eric

[aerohead]

Originally Posted by chaster

I wasn't doubting that there would be interference effects. I was just wondering what the *magnitude* of those interference effects would be.

I agree with your predictions of torque load on a single pole mount.

Eric

Eric,if you need a specific load for a given spacing,I would not be able to provide that,as I do not possess data from heliostat research conducted in windtunnels.
What I would pose to you,is to imagine a PV array,with the panels spaced far enough apart,that there was no aerodynamic interaction present if you will,and the scale of such a support structure necessary to allow this condition,then any possible benefit from a structure so large as that,when common engineering practice dictates that we use the minimum amount of material for any given solution.

[chaster]

Originally Posted by aerohead

Eric,if you need a specific load for a given spacing,I would not be able to provide that,as I do not possess data from heliostat research conducted in windtunnels.

Somehow, I get the feeling you are interpreting my statements as an argument or disagreement when they are not. I didn't request "specific load" data, nor was I expecting it...

The OP was asking a general question, my opinion is that "it depends". It's not an argument.

Eric

[aerohead]

Originally Posted by chaster

Somehow, I get the feeling you are interpreting my statements as an argument or disagreement when they are not. I didn't request "specific load" data, nor was I expecting it...

The OP was asking a general question, my opinion is that "it depends". It's not an argument.

Eric

Eric,no,I'm okay with your statement,it's just that 'magnitude' inferred some kind of quanta,and I'm just not up to the task on providing meaningful data.
It's a good question.
One of the first projects for the Texas Tech Aerodynamics Lab was heliostat research for solar farms,which might have addressed the interference issue.I suspect it did.
The 'scope' of what they were doing seemed beyond the domain of the individual,so I didn't pay much attention.
It would be of value now as it is germane to PV installs.

[Xringer]

Story here:
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