Someone was proud of their work. Make sure you have a barf bag ready

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jaggedben said:
Probably it will be just fine. These systems are engineered for such. I'd be more concerned about the building supporting the weight. But the poor electrical work doesn't necessarily tell us anything about whether the structural engineering was done right.
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I'm not saying the equipment can't take the wind, but really doubt the cinder blocks will hold it down in some of the storms frequently seen around here. It will need mechanical securing at the very least and not just a weighted object for securing. All you need is for one to shift a little during today's storm and now it is even easier to move during the next storm, when it does move it maybe catches onto another unit and pretty soon many are affected.
 
kwired said:
I'm not saying the equipment can't take the wind, but really doubt the cinder blocks will hold it down in some of the storms frequently seen around here. It will need mechanical securing at the very least and not just a weighted object for securing. All you need is for one to shift a little during today's storm and now it is even easier to move during the next storm, when it does move it maybe catches onto another unit and pretty soon many are affected.
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With all respect I don't think you've researched the subject. This method is common, industry standard even, and there's plenty of engineering to back up the proper way to do it. Mechanical securing may be required where earthquakes are a concern, but the ballast is supposed to handle wind. There was a ballasted system in Puerto Rico that mostly survived hurricane Maria; even though it didn't 100% stay on the roof, the company was crowing about how much it exceeded its design standard.

Of course one has to follow the engineering guidelines carefully, which shouldn't be taken for granted especially in this case. Also, to repeat, you can follow the manufacturer's guidelines for dealing with wind uplift and still fail to do due diligence on the dead load on the building structure. It is a common method for commercial buildings but every now and then someone asks me about doing it on residential and usually the framing of residential buildings (especially older ones) is not up to snuff.

This is really a side subject to the OP. This is a large enough system that likely the players involved in designing and building it were different than those installing it. As I said, the cringe-worthy electrical work (or lack thereof) doesn't necessarily tell us anything about the engineering quality of the design.
 
mbrooke said:
Are all those panels being held down by cinder blocks? :eek::eek:
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If you look carefully at the pictures you can see that the frames have holders that seem specifically designed to accommodate the ballast that has been installed.
 
rlundsrud said:
Actually that is not atypical, I took the PV class at my union apprenticeship school and they said that was ok for that type frame.
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gadfly56 said:
If you look carefully at the pictures you can see that the frames have holders that seem specifically designed to accommodate the ballast that has been installed.
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But in the least I would imagine that they need to be anchored down to the roof or structural members.
 
mbrooke said:
But in the least I would imagine that they need to be anchored down to the roof or structural members.
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I doubt you want to attach it to the roof itself. It's what, a couple of layers of membrane over some 16 gauge steel attached to some purlins? If the wind uplift forces are high enough to float the arrays, it's just adding insult to injury to peel the roof off along with them. And if you did secure through the roof, every penetration is a leak path. Not might be, is. Same issue with securing to any substructure; you have to penetrate the roof membrane.
 
The storm that came through last summer and toppled dozens of center pivot irrigation systems and relocated a few grain bins would have never moved those PV units?? They have more of a natural sail built into them than the center pivot systems have. Ever tried to carry a 4 x 8 sheet of plywood by yourself in just a 10 MPH wind?

Guess I should suggest to farmers they need to hang cinder blocks on their center pivot systems and then they won't ever tip over in high winds:cool:
 
gadfly56 said:
I doubt you want to attach it to the roof itself. It's what, a couple of layers of membrane over some 16 gauge steel attached to some purlins? If the wind uplift forces are high enough to float the arrays, it's just adding insult to injury to peel the roof off along with them. And if you did secure through the roof, every penetration is a leak path. Not might be, is. Same issue with securing to any substructure; you have to penetrate the roof membrane.
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I agree, but also disagree in that there has to be a way to mount them to the truces. Come Hurricane with 100MPH winds I can see those things being blown off several times over. But then again I will admit that I am purely going by limited knowledge as I am not a structural engineer.
 
kwired said:
The storm that came through last summer and toppled dozens of center pivot irrigation systems and relocated a few grain bins would have never moved those PV units?? They have more of a natural sail built into them than the center pivot systems have. Ever tried to carry a 4 x 8 sheet of plywood by yourself in just a 10 MPH wind?

Guess I should suggest to farmers they need to hang cinder blocks on their center pivot systems and then they won't ever tip over in high winds:cool:
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I'm sure it would have worked if properly engineered. It's mainly a matter of knowing the wind speed of the storm you expect and calculating the number of cinder blocks needed.
 
jaggedben said:
I'm sure it would have worked if properly engineered. It's mainly a matter of knowing the wind speed of the storm you expect and calculating the number of cinder blocks needed.
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So would going out there minutes before the storm hits and driving in some tie down anchors - wait we have 20 pivots that might need anchored down:D

Having the system running during the storm adds water weight though. 6 inch pipe about a quarter mile long holds a lot of water.
 
kwired said:
So would going out there minutes before the storm hits and driving in some tie down anchors - wait we have 20 pivots that might need anchored down:D

Having the system running during the storm adds water weight though. 6 inch pipe about a quarter mile long holds a lot of water.
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Probably the simplest, fastest, way to anchor the system in a high wind condition.
 
gadfly56 said:
Probably the simplest, fastest, way to anchor the system in a high wind condition.
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Until you find out the storm took out POCO distribution and nothing works, or you are on a load management agreement and you happen to be under load control at that time (they use wireless controls to disable your well during peak demand periods under this agreement):blink:


Though many guys can start their systems from an app on their phone these days, so they could be halfway across the country and still do so.
 
kwired said:
Won't keep them in place with the wind gusts we often see during thunderstorms around here.
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Actually, they will if the array is engineered correctly. Most PV rooftop racking companies will take location climatological data (wind maps) and building dimensions and design the concrete block layout so that the modules won't blow away.
 
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