Is A DIY Solar Array Ground Mount Worth It?

[Zeigh]

Hello,

I have another post asking if others had used Kee-Klamps (or Speed-Rail) to construct their own solar array ground mount. Now I am wondering if it is worth it in the long run to take on the project or have an installer do it. I certainly have the ability and equipment to build a system right now, but the data required by my County building department is daunting and I might have to involve an engineer. Buying a prepackaged commercial design looks as though it would cost even more. While I crunch the numbers and hair still left on my head that will inevitably be pulled out with such a project regardless, I would be interested in the feedback of those more experienced than I.

BTW, my design is for a 50 panel system, ideally 10 columns of 5 horizontal panels high.


Peace,
Dr. Z.

[J.P.M.]

Hello,

I have another post asking if others had used Kee-Klamps (or Speed-Rail) to construct their own solar array ground mount. Now I am wondering if it is worth it in the long run to take on the project or have an installer do it. I certainly have the ability and equipment to build a system right now, but the data required by my County building department is daunting and I might have to involve an engineer. Buying a prepackaged commercial design looks as though it would cost even more. While I crunch the numbers and hair still left on my head that will inevitably be pulled out with such a project regardless, I would be interested in the feedback of those more experienced than I.

BTW, my design is for a 50 panel system, ideally 10 columns of 5 horizontal panels high.


Peace,
Dr. Z.

All in one plane ?

[Zeigh]

All in one plane ?

Yes, if feasible. I have seen a few photos of five-panel high configurations, although most of the designs online only show four panels high.


Peace,
Dr. Z.

[J.P.M.]

Yes, if feasible. I have seen a few photos of five-panel high configurations, although most of the designs online only show four panels high.


Peace,
Dr. Z.

Good luck on the structural design. What's the tilt ?

[Amy@altE]

Go to IronRidge's web site and use their design tool. http://www.ironridge.com/sga/general They just added a 5 panel high in landscape option. 5 high and 10 wide should not be a problem. They have a nice system where you buy their connectors and you supply the 3" Schedule 40 piping yourself to save on shipping costs. They will output the engineering numbers that the permits will want, as well as a BoM. Don't worry about the pricing they list, it is MSRP, you will get it for less than that from their distributors.

[J.P.M.]

Go to IronRidge's web site and use their design tool. http://www.ironridge.com/sga/general They just added a 5 panel high in landscape option. 5 high and 10 wide should not be a problem. They have a nice system where you buy their connectors and you supply the 3" Schedule 40 piping yourself to save on shipping costs. They will output the engineering numbers that the permits will want, as well as a BoM. Don't worry about the pricing they list, it is MSRP, you will get it for less than that from their distributors.

Suit yourself, but depending in the pitch (tilt), and the design criteria for wind as well as other considerations, I'd be real careful about the entire design, including anchorage and footings.

Amy - no disrespect - you're a structural engineer ?

[Amy@altE]

Suit yourself, but depending in the pitch (tilt), and the design criteria for wind as well as other considerations, I'd be real careful about the entire design, including anchorage and footings.

The design tool also recommends minimum footing sizes. It includes tilt, snow load, and wind speed criteria. Obviously it isn't for everyone, but it is a very useful tool to help decide if it is worth it to DIY.

[Amy@altE]

Amy - no disrespect - you're a structural engineer ?

I am not an engineer (and didn't stay at a Holiday Inn last night), but IronRidge has PE Certified support available if needed.

[J.P.M.]

I am not an engineer (and didn't stay at a Holiday Inn last night), but IronRidge has PE Certified support available if needed.

Pay your money, take your choice. Soil analysis/footings too ?

That's a back of envelope analysis and maybe good for prelim. quote, but not as a serious design. A 5 X 10 will take a little more work on the details.

[Amy@altE]

Pay your money, take your choice. Soil analysis/footings too ?

Soil Class

Ground Mount Design Assistant includes three different soil class options. Class 4, the default, is the most conservative soil class. If you would like to use either Class 2 or 3, you will need to consult a civil or professional engineer and soils report to verify soil bearing capacity. You can also check with your local building authority, as some may have an existing soil report for your project location already.

Based on your selected soil class, Design Assistant will use the foundation pressure, lateral bearing and friction coefficient values to calculate the minimum hole depth required for your piers.

TABLE 1806.2, PRESUMPTIVE LOAD-BEARING VALUES
Internal Building Code 2012 - Chapter 18: Soils and Foundation
VERTICAL FOUNDATION PRESSURE (psf) LATERAL BEARING PRESSURE (psf/ft) COEFFICIENT OF FRICTION

2 - Sedimentary and folliated rock 4,000 400 0.35
3 - Sandy gravel and/or gravel (GW and GP) 3,000 200 0.35
4 - Sand, silty sand, clayey sand, silty gravel and clayey grabel (SW, SP, SM, SC, GM, and GC) 2,000 150 0.25

[J.P.M.]

Soil Class

Ground Mount Design Assistant includes three different soil class options. Class 4, the default, is the most conservative soil class. If you would like to use either Class 2 or 3, you will need to consult a civil or professional engineer and soils report to verify soil bearing capacity. You can also check with your local building authority, as some may have an existing soil report for your project location already.

Based on your selected soil class, Design Assistant will use the foundation pressure, lateral bearing and friction coefficient values to calculate the minimum hole depth required for your piers.

TABLE 1806.2, PRESUMPTIVE LOAD-BEARING VALUES
Internal Building Code 2012 - Chapter 18: Soils and Foundation
VERTICAL FOUNDATION PRESSURE (psf) LATERAL BEARING PRESSURE (psf/ft) COEFFICIENT OF FRICTION

2 - Sedimentary and folliated rock 4,000 400 0.35
3 - Sandy gravel and/or gravel (GW and GP) 3,000 200 0.35
4 - Sand, silty sand, clayey sand, silty gravel and clayey grabel (SW, SP, SM, SC, GM, and GC) 2,000 150 0.25

How far off the ground ?
Tilt ?
Seismic zone.
Etc .?

[J.P.M.]

I am not an engineer (and didn't stay at a Holiday Inn last night), but IronRidge has PE Certified support available if needed.

Which anyone using their services will likely need and pay for accordingly as required by the JHA.

[Amy@altE]

Which anyone using their services will likely need and pay for accordingly as required by the JHA.

Not really. I sell tons of these systems, and it has been a very rare occasion when the engineering output from the tool has not been accepted by the AHJ. I can't even think of one off the top of my head.
I made up some inputs to show an example of the output. Design Assistant _ Ground Mount _ IronRidge_example.pdf

[J.P.M.]

Not really. I sell tons of these systems, and it has been a very rare occasion when the engineering output from the tool has not been accepted by the AHJ. I can't even think of one off the top of my head.
I made up some inputs to show an example of the output. [ATTACH]6125[/ATTACH]

Suit yourself. Good for prelim. quote. If the AHJ buys off on it - good to go. I'd only suggest not to be surprised if there's more to the story.

[Amy@altE]

Suit yourself. Good for prelim. quote. If the AHJ buys off on it - good to go. I'd only suggest not to be surprised if there's more to the story.

Totally agree.