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solar pergola on pavement, only weighted down

CableGuy

CableGuy

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I am looking to build an array in a small parking lot. it will only be in service 2-3 years, and i don't want to disturb the pavement. the top is 27.5ft x 11.5ft, with panels almost flat roughly 8.5ft above ground. it will be pitched slightly but only for runoff reasons. Certainly classified as temporary and not grid-tied.

There's 72 cinderblocks per pallet, @ 33lbs per block, so 2 pallets is over 4,600lbs. they fit nicely between the posts in double rows of 10 with a 2x6 PT slid between them which is bolted through the 4x4 posts at each end. see below...

3 layers in the center (60 blocks) 2000lbs or 1000lbs per center post
2 layers (40 blocks) is 1300lbs on each end, or 650lbs per corner.

thoughts? see image below
 
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a strong enough wind it will tip, my thoughts

a friend had a shipping container for a temporary shed, it wasn't anchored down and in a hurricane it rolled into the neighbours property
 
great idea, love the concept! do some wind load calcs. if it's truly black-top pavement, you could easily put some grounding rods down through it to secure it. black-top pavement is super easy to patch up.
 
pollenface said:
a strong enough wind it will tip, my thoughts

a friend had a shipping container for a temporary shed, it wasn't anchored down and in a hurricane it rolled into the neighbours propert
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How many empty shipping containers are in the world right now.

I would think most wind would blow through this laterally. Uplift is what I am worried about
 
Considering a lot of the temporary structures on parking lots that are thrown up yours looks fairly substantial. A lot of it will depend on wind loads. however a storm big enough to blow down your temporary structure is likely large enough to flip cars and trucks about. My biggest structural concern would be a lack of sideways bracing.
 
Mattb4 said:
Considering a lot of the temporary structures on parking lots that are thrown up yours looks fairly substantial. A lot of it will depend on wind loads. however a storm big enough to blow down your temporary structure is likely large enough to flip cars and trucks about. My biggest structural concern would be a lack of sideways bracing.
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That's kind of what I was thinking, I have a 14ft box trailer parked next to this and it weighs 2200lbs. If we are talking wind that would blow over a box trailer, I am 5x more concerned about the trailer.

Those diagonal braces need to be longer. I dont want to lose the ability to park cars under it, so it needs to be open but it can be improved for sure.

Thanks
 
CableGuy said:
Those diagonal braces need to be longer. I dont want to lose the ability to park cars under it, so it needs to be open but it can be improved for sure.
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If you don't need to be able to pull all the way through, just put them on the 'back' side only, above the hood of the car. plenty of space there.
 
The parking cover the local walley world put up is gone since the last hurricane this year in Fl. Steel frame work anchored in concrete. The front of the near-by dollar store, concrete block is gone also. This is the worst we got 12 miles away. The hurricane came a shore 7 miles from us with 130 mph winds. We were on the least bad side but walley world was on the worst side.
 

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CRenner said:
Do you have to worry about snow load?
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I live 1 exit away. If we get over a foot of snow, I will also be concerned about power lines being down and I will be there clearing the snow off to be ready for the sun.
 
i changed the pitch to be 5 degrees and made the rear angle braces longer. i could extend the main length 2x6 lumber to stick out to add bracing, but i may be tempted to just add more panels.

pergola-forum3d.jpg

pergola-forum3e.jpgpergola-forum3f.jpg
 
If anyone is curious, these are NE solar 370w panels, just shy of 6000w total for under $1500 shipped. Lumber is sitting at $450 and cinder blocks around $200.
 
I built a pergola a while back to hold 12 panels. I did concrete my 4x4's into the ground tho about 3 ft. I went out there during a storm recently (60-70mph winds) and the thing was barely moving. After that, I'm not too worried about wind on my pergola. As to your issue, they do sell metal brackets that bolt into concrete to hold pergola posts. I'd just use that.

Here is my pergola for inspiration:

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I think that is too big a sail, and no where near enough hold down.
Not difficult to calculate the horizontal force required to tilt and lift the cinder blocks, which aren't very heavy.

Consider either driven posts or anchors that are turned into the dirt as an auger. Or concrete foundations.
Just built it so they can be cut flush or recessed and patched over.
 
Hedges said:
I think that is too big a sail, and no where near enough hold down.
Not difficult to calculate the horizontal force required to tilt and lift the cinder blocks, which aren't very heavy.

Consider either driven posts or anchors that are turned into the dirt as an auger. Or concrete foundations.
Just built it so they can be cut flush or recessed and patched over.
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the concrete weighs what a pickup truck does. how many pickup trucks do you think i need to hold down 16 solar panels.
 
tmprof said:
I built a pergola a while back to hold 12 panels. I did concrete my 4x4's into the ground tho about 3 ft. I went out there during a storm recently (60-70mph winds) and the thing was barely moving. After that, I'm not too worried about wind on my pergola. As to your issue, they do sell metal brackets that bolt into concrete to hold pergola posts. I'd just use that.

Here is my pergola for inspiration:
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looks awesome! i like how you hung the 2x6 on your "4x6" beams and attached the fake ends. at first i thought it was slotted. i think that's a better call....
 
Q-Dog said:
2. On a movie set I have seen a 20' X 20' rag on a frame pull a truck when the wind came up suddenly.
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to that point, whatever ballast is deemed adequate for a 24x12 tent in a parking lot should be sufficient for my setup. i'm going to look into that
 
I'm in So Cal and our top winds in this area are about 70 mph. The wind rating has to be for 110 mph to be approved/permitted. My arrays required almost 10k-12k pounds of concrete ballast at the base to meet this stress level. They are not big arrays and are comparable to what is pictured. You can fill sola tubes to meet ballast needs since you can space them every 5-8 feet, you can build 24x24x24 inch concrete cubes and have them sunk partially into the ground and the poles put into them when the pour happens. They will weight about 1k pounds each. And you can pour a concrete ground perimeter between and including your posts that would be about 18x18x12-18 to create the ballast.

To me, the problem with building with wood is either having it inserted in the concrete during the pour and not coming loose or rotting over time from water intrusion or bugs. Bolting down a wooden post to concrete may sound good, but I think it is important to know the load capacity of the threads (like Simpson strong ties) in the bolts to get the correct depth and number needed to be safe from wind damage.

Many building supply and fencing companies sell adapters so that you can sink a galvanized steel post into concrete and then place a vinyl post over the steel one using the adapter for appearances.

Just my thoughts.

Lastly, the man who uses Superstrut is a smart man IMO!
 
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