Structural Design for Ground Mount

[mazgaon]

Hello,

I am working on with Town of South Windsor in Connecticut to get approval for my Ground mount system. I have the Zoning department visit and bless the location and everything seem to be going good until i was asked to submit a CT Engineer Certified Structural design for the EG4 BrighMount Ground Mount Kit.

The EG4 manufacturer had sent me their structural analysis and it seems it was for 105mph wind speed and CT needs 120 mph wind speed analysis but moreover signed by CT Certified Engineer.

I tried looking at Google but could not find any CT Certified Engineer for this job.... Any suggestion?

I tried GreenLancer and they quoted me $650 for signup.

Thanks,
Dinesh

 

[OzSolar]

IMHO, Greenlancer's price doesn't sound too bad. Hopefully this will bump your post and get you some answers.

To be honest I'm surprised the EG4 Brightmount passes a 105 MPH structural analysis. It looks to me like it wouldn't take much effort at all to snap off those bolts. And if they didn't fail, they'd break concrete they are mounted to. There's a lot of lever arm there, particularly on the high side.

That being said I suspect you may have a challenge getting a "traditional" structural engineer to sign off on it. Not saying it's bad product, in fact I think it's a great product for the price point it lands at. It will likely be fine in 99% of applications but engineers don't put thier stamps on things if they aren't 100%.

 

[mazgaon]

IMHO, Greenlancer's price doesn't sound too bad. Hopefully this will bump your post and get you some answers.

To be honest I'm surprised the EG4 Brightmount passes a 105 MPH structural analysis. It looks to me like it wouldn't take much effort at all to snap off those bolts. And if they didn't go they'd break concrete they are mounted to. There's a lot of lever arm there, particularly on the high side.

That being said I suspect you may have a challenge getting a "traditional" structural engineer to sign off on it. Not saying it's bad product, in fact I think it's a great product for the price point it lands at. It will likely be fine in 99% of applications but engineers don't put thier stamps on things if they aren't 100%.


View attachment 229741

Thanks OZSolar... Is there any other DIY friendly ground mount structure that is available in the market that could pass the Structure design.

What is the diameter of the concrete you lay out there.... The other challenge is the manual says it should be almost 20 inch wide... I could not find this big sonotube in HomeDepot or Lowes.

Thanks,
Dinesh

 

[Solar Guppy]

IronRIdge is the industry gold standard and has fully engineered options ( online design tools as well ) . You will almost always be required to get PE approval for plans when getting permits, not just the solar mounting, but whole system. Green Lancer is whom I used to get the plan's PE wet stamped.

 

[cdsolar]

Here is my AHJ approved Brightmount. I did not need stamped drawings, I only needed to adhere to the manufacturers' instructions. I replaced the blocks from the manual with 24 inch diameter sonotubes, 18" above ground as per instructions, and 36" below ground to frost depth. Was ready to show AHJ that the filled sonotubes were heavier than the blocks, but he didn't ask.

Post your Ground Mount Setup

About 4ft deep and 6 bags. Thats a 14ft pole, reused oilfield pipe. Right on. I'm guessing 6 x 60# bags of ready-mix? That reused oilfield pipe is the stuff. Saw some folks here n Alaska make a massive fence around their garden using some of that and what a great way to reuse metal.

diysolarforum.com

 

[OzSolar]

Thanks OZSolar... Is there any other DIY friendly ground mount structure that is available in the market that could pass the Structure design.

What is the diameter of the concrete you lay out there.... The other challenge is the manual says it should be almost 20 inch wide... I could not find this big sonotube in HomeDepot or Lowes.

Thanks,
Dinesh

Of course "DIY Friendly" can mean a lot of things to a lot of people. I'm getting ready to build a ~4kW skid mounted array that I drag around my place with a tractor depending on what I need from it. Most of the time it will be used for pumping water from a spare well on my property to a pond I'm expanding but I'm going to rely completely on it's on weight plus some ballast to keep it from flying away 99% of the time. No permits required in my area though.

You might try to go down the road of a "mobile" installation. There are people here who say they mounted thier solar panels on a bus, a trailer or shed with wheels on it therefore sidestepping the permanent install requirements. There's been some really creative ideas! Hopefully one of them will see this and chime in.

 

[rhino]

Thanks OZSolar... Is there any other DIY friendly ground mount structure that is available in the market that could pass the Structure design.

https://www.sinclair-designs.com/. Their standard design is rated for 125mph and you can get it stamped by engineer.

 

[Gttnsun]

Solar panels are basically a big wind sail, the concrete needs to be able to hold the panels down to the ground in big wind gusts. The eg4 brighmount paperwork is saying it will only hold 1 550w panel in 105 mph wind.
There are many companies that sell ground mount kits that have engineering paperwork included, pier depth and width depends on a few factors, panel size and quantity, angle, wind load snow load, and soil conditions.
I built a Tamarack Ground mount

Ground Mount System | Tamarack Solar Products

The Tamarack Ground Mount System allows you to build a simple, low-cost structure with columns of 3 or 4 modules in landscape orientation.

tamaracksolar.com

 

[mazgaon]

Thanks for your input everyone. I will explore the other options suggested by everyone above....

 

[mazgaon]

I did look into Sinclair ground mount. They seem very good for adjustable angle option but $2500 delivery charges throws the equation out with final cost of $5700 with shipping. The IronRIdge Cost is also around $3800 plus i need to pay for Engineer to sign Structural analysis. The third option i looked Tamarack. The Cost on that is $2700. Green Lancer charging $645 for structural analysis.

This DIY town approval gig is turning out to be expensive. I wish i could have got away without the Town approval but i guess this is what we need to pay for Grid-Tie system.

 

[mazgaon]

Another interesting part is that i have designed the system based on the manufacturer manual and provided CT State Certificate for Tamarack. This Structural analysis Certificate is already Certified by State of Connecticut Licensed Engineer. I used the information provided in that Certificate on my design with reference to exact page number. All seem good but the Town says they still need the Engineer to sign because he does not have time to go over the pages i submitted.

 

[Gttnsun]

Another interesting part is that i have designed the system based on the manufacturer manual and provided CT State Certificate for Tamarack. This Structural analysis Certificate is already Certified by State of Connecticut Licensed Engineer. I used the information provided in that Certificate on my design with reference to exact page number. All seem good but the Town says they still need the Engineer to sign because he does not have time to go over the pages i submitted.

That is unfortunate.
I don't understand how paying another Engineer to do the same work again helps solve anything. The Tamarack engineering satisfied my building department.
In my experience working with the local AHJ it can vary from person to person working in the same office, I like asking which part of the code they are referring to, or which department policy they are using. If it says you need engineering and you provide engineering, they need a better reason then they don't have time to accept it. At my AHJ the people at the front desk seem to say no alot, even when they are wrong.

 

[mazgaon]

It is frustrating. I spoke to the same company who Certified the Tamarack system if they can review and endorse my design and they will charge $1400 for it. Frustrating and Ridiculous.

 

[rhino]

Is it a possibility for you to go pick up the Sinclair mount yourself? It is very compact just long. Mine was if I recall 14ft long:

 

[Gttnsun]

Try getting the ground mount permitting requirements in writing. Maybe they have a application checklist.
For my Tamarack mount I printed out the first 4 pages, (which is the engineering documents with stamp) on regular size paper, I printed the last 3 pages on bigger paper because they are the blueprints, I also included table S5 and F5 because I am exposure category 3, but it all depends on the site conditions.
I was installing a whole inverter and battery system also so I also needed to provide a single line diagram and cut sheets for all the components.

 

[Gttnsun]

Tamarack also has a design tool to help get the right documents and parts.

https://tamarack-configurators.cloudapps.ltd/ground-mount/#get-started-tab

 

[mazgaon]

Is it a possibility for you to go pick up the Sinclair mount yourself? It is very compact just long. Mine was if I recall 14ft long:
View attachment 232275

I wish. They are located in MIchigan and i am in Connecticut. A very very long drive plus i need a uhaul to get this big item.

 

[mazgaon]

Try getting the ground mount permitting requirements in writing. Maybe they have a application checklist.
For my Tamarack mount I printed out the first 4 pages, (which is the engineering documents with stamp) on regular size paper, I printed the last 3 pages on bigger paper because they are the blueprints, I also included table S5 and F5 because I am exposure category 3, but it all depends on the site conditions.
I was installing a whole inverter and battery system also so I also needed to provide a single line diagram and cut sheets for all the components.

They are ok with my DIY electric diagram. Just the structure design needs to be signed by licensed engineer.

 

[mazgaon]

Tamarack also has a design tool to help get the right documents and parts.

https://tamarack-configurators.cloudapps.ltd/ground-mount/#get-started-tab

I used this tool Plus their technical support person Bruce is so nice to talk with.

See attached my design. This document was part of my package along with electric design.

 

[outboard1196]

I used this tool Plus their technical support person Bruce is so nice to talk with.

See attached my design. This document was part of my package along with electric design.

That document has some personal info .
I'm in Ct as well , is this a state wide requirement or is it by town ?

 

[mazgaon]

All Info is now public.... What is it that i know about me that web does not.
I am working with my Town of South Windsor.

 

[Gttnsun]

Looks like you provided what they want, plans signed by a Engineer.
Maybe ask them to give you a response in writing why it isn't good enough?

 

[mazgaon]

Looks like you provided what they want, plans signed by a Engineer.
Maybe ask them to give you a response in writing why it isn't good enough?

This is the response i got "Put on the drawings what you plan on using where and I will review that. Needs to be specific, not one or maybe the other."

I am not sure what else they need. I plan on putting the details down to what Schedule Pipe, what Tamarack rail etc.

 

[Gttnsun]

Sounds like a being really strict.
Did you give them the 4 pages that look like this?
It has some very specific information.
Maybe you can just show that and highlight the pier depth and diameter on the right table

 

[marionw]

IMHO, Greenlancer's price doesn't sound too bad. Hopefully this will bump your post and get you some answers.

To be honest I'm surprised the EG4 Brightmount passes a 105 MPH structural analysis. It looks to me like it wouldn't take much effort at all to snap off those bolts. And if they didn't fail, they'd break concrete they are mounted to. There's a lot of lever arm there, particularly on the high side.

That being said I suspect you may have a challenge getting a "traditional" structural engineer to sign off on it. Not saying it's bad product, in fact I think it's a great product for the price point it lands at. It will likely be fine in 99% of applications but engineers don't put thier stamps on things if they aren't 100%.


View attachment 229741

Cut a 3/4 inch piece of plywood several inches larger than the "foot" mount with the holes. Drill four holes in the plywood that line up with the holes in the "foot" mount. Using at least 6 inch galvanized bolts and nuts on both sides of the plywood install the bolts in the plywood such that the "head" is furthest from the plywood and the nuts are holding the bolts tightly in place with no threads exposed on the top nut (this will give you 3/4 inch thread and the thickness of the nut after the concrete is set). Pour the concrete and while still wet insert the bolts down into the concrete until the plywood is level with the top (not in) the concrete and use a stick or rod to agitate the concrete to ensure the bolts are completely encased in the concrete. When the concrete is set/dry remove the top nuts and the plywood. The "foot" mount should slip down over the protruding bolts, add washers and nuts.