Is A DIY Solar Array Ground Mount Worth It?

[SunEagle]

That picture was taken within days of the panels going up. That maple tree has been pruned about 80-90%. Planning on doing some more before the leaves come out, but this summer I'll be renting a large beam type lift to paint the house and then I can get it completely trimmed without falling off of a ladder. There's an oak tree to the right of it which is causing early morning shade and I've convinced my wife that I can take it down.

I understand the danger of using a ladder to trim tree branches. I was out this weekend with my 16 foot pole saw. It was nice to clean up my big Oak with both feet on the ground.

As for taking down your oak tree, just make sure it falls away from those panels.

[JFinch57]

Looks like that array on the right is getting some shading from those trees behind it. You may want to look into some pruning.

That picture was taken within days of the panels going up. That maple tree has been pruned about 80-90%. Planning on doing some more before the leaves come out, but this summer I'll be renting a large beam type lift to paint the house and then I can get it completely trimmed without falling off of a ladder. There's an oak tree to the right of it which is causing early morning shade and I've convinced my wife that I can take it down.

[SunEagle]

I did my own DIY ground mount with 45 panels using Unirac and 2" galvanized pipe. Unirac also gives all of the footing requirements, engineering, PE seal for your state, etc but my county didn't want any of it since it's not on the roof. Their configuration tool only allows for 4 high in landscape. When I realized that I would exceed the 12' maximum structure height due to my 55" ground slope over 60' I split the array in the middle and worked in 4' overhangs at each end to take up the missing panels, which are not really mounted to spec. I cross strapped them in the middle since they are portrait, also added 2 angled braces on the end with 3 that were not installed when the pictures were taken. I can tell you that pouring almost 5 yards of concrete with a powered concrete buggy took about 3 hours and the concrete company was not happy! Luckily they did not charge extra, which they could have. There were a lot of rocks and that caused the sonotubes not to be inline with each other, which is only cosmetic. Plan on using a laser level to determine the distance to the bottom of each hole so that when you cut the pipe the top is level. I pounded rocks at the bottom then put a small piece of cheap cedar fence to get a firm bottom. Should have put plastic bags around the sonotubes as a few collapsed before we could pour the cement and it wasn't fun digging them out at 40" with a fence post hole digger! Here are some pictures:[ATTACH=CONFIG]6249[/ATTACH][ATTACH=CONFIG]6250[/ATTACH][ATTACH=CONFIG]6251[/ATTACH][ATTACH=CONFIG]6252[/ATTACH]

Looks like that array on the right is getting some shading from those trees behind it. You may want to look into some pruning.

[JFinch57]

I did my own DIY ground mount with 45 panels using Unirac and 2" galvanized pipe. Unirac also gives all of the footing requirements, engineering, PE seal for your state, etc but my county didn't want any of it since it's not on the roof. Their configuration tool only allows for 4 high in landscape. When I realized that I would exceed the 12' maximum structure height due to my 55" ground slope over 60' I split the array in the middle and worked in 4' overhangs at each end to take up the missing panels, which are not really mounted to spec. I cross strapped them in the middle since they are portrait, also added 2 angled braces on the end with 3 that were not installed when the pictures were taken. I can tell you that pouring almost 5 yards of concrete with a powered concrete buggy took about 3 hours and the concrete company was not happy! Luckily they did not charge extra, which they could have. There were a lot of rocks and that caused the sonotubes not to be inline with each other, which is only cosmetic. Plan on using a laser level to determine the distance to the bottom of each hole so that when you cut the pipe the top is level. I pounded rocks at the bottom then put a small piece of cheap cedar fence to get a firm bottom. Should have put plastic bags around the sonotubes as a few collapsed before we could pour the cement and it wasn't fun digging them out at 40" with a fence post hole digger! Here are some pictures:Soar Panels Done2.jpgSolar Panels Rear2.jpgSolar Panels RearA.jpgSolar2.jpg

[SunEagle]

Like I wrote, if the AHJ signs off on it you're good to go. Just read the fine print and know that the AHJ usually/often is only charged with checks for conformance to code(s), not necessarily suitability of design. One idea behind engineering design is safety with code conformance, not code compliance simply for its own sake.

There is a difference.

Or as us non structural engineers say. Just add 50% more concrete in the foundation.

[J.P.M.]

Thanks for everyone's input so far...

The IronRidge site mentioned is very well designed and seems to pump out all the technical documentation that I would need to make a building inspector happy (if that is actually possible). That free service alone is worth it, as one of the professional engineering quotes that I got just to do the calculations without drawings on my own design was $1500! I am still going to investigate a few more leads, but IronRidge or one of their competitors with similar free documentation is probably going to get my business.


Peace,
Dr. Z.

Like I wrote, if the AHJ signs off on it you're good to go. Just read the fine print and know that the AHJ usually/often is only charged with checks for conformance to code(s), not necessarily suitability of design. One idea behind engineering design is safety with code conformance, not code compliance simply for its own sake.

There is a difference.

[Zeigh]

Thanks for everyone's input so far...

The IronRidge site mentioned is very well designed and seems to pump out all the technical documentation that I would need to make a building inspector happy (if that is actually possible). That free service alone is worth it, as one of the professional engineering quotes that I got just to do the calculations without drawings on my own design was $1500! I am still going to investigate a few more leads, but IronRidge or one of their competitors with similar free documentation is probably going to get my business.


Peace,
Dr. Z.

[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.

[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]

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.]

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.

[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 .?

[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.]

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]

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.