Ground mounting setup

[bcroe]

NSbuba.jpgimage_9054.jpg Here are a couple pictures of what is buried, and above ground details. You can just see the edges of a linolium square
between the aluminum angle and the wood, on a 7" SS bolt. Bruce Roe

[Dsspro]

Bruce,

Thanks for sharing!!!

How far down did you go down for your concrete posts?

[bcroe]

Bruce, How far down did you go down for your concrete posts?

Somebody else did the south facing concrete with coated aluminum bars embedded at the top. As I recall they did a bit of
a footing in a post hole with some rebar, about 48" down. Then a tube. That array is all custom drilled 6061 aluminum,
good stuff. At the time it might have been cheaper than racking, but at last check aluminum had gone way up. Bruce

[Mike90250]

I'd like to discourage folks from thinking about using aluminun with concrete

http://www.concreteconstruction.net/how-to/repair/the-aluminum-and-concrete-controversy_o

[J.P.M.]

I'd like to discourage folks from thinking about using aluminun with concrete
http://www.concreteconstruction.net/...-controversy_o

I'll second that one.

[SunEagle]

I'd like to discourage folks from thinking about using aluminun with concrete
http://www.concreteconstruction.net/...-controversy_o

I agree that aluminum and concrete are not a good combination. But Bruce mentioned "coated aluminum" so I wonder what the "coating" was that might inhibit corrosion and cracking.

[J.P.M.]

I agree that aluminum and concrete are not a good combination. But Bruce mentioned "coated aluminum" so I wonder what the "coating" was that might inhibit corrosion and cracking.

Something that's also, among other things an electrical isolator. Most of the problem is galvanic.

[bcroe]

Right, don't put aluminum directly in concrete. This was some kind of coating for this ap, done by the
aluminum supplier. So far looks fine. Bruce

[Kuma]

Planning a dyi 5kw+ solar ground mount in Nor Cal. Have looked at many rack options and still have not ruled out a PT frame structure. I live in 5 acres and have MANY PT fence posts in concrete 12+ years old that still look very good. And these are in the sun all day. Unlike a solar frame structure which it seems a majority of the posts would be shaded at different parts of the day. The 10+ year old PT deck structure that is elevated 6' on one side due to slope conditions, also looks great. The decks 2x6 PT floor joists are in excellent condition. I figure, given my age, if the PT lasts 20+ years, it may outlast me. And if I last more then 20, the last thing of concern would be a 20 yr old solar system.

[J.P.M.]

Planning a dyi 5kw+ solar ground mount in Nor Cal. Have looked at many rack options and still have not ruled out a PT frame structure. I live in 5 acres and have MANY PT fence posts in concrete 12+ years old that still look very good. And these are in the sun all day. Unlike a solar frame structure which it seems a majority of the posts would be shaded at different parts of the day. The 10+ year old PT deck structure that is elevated 6' on one side due to slope conditions, also looks great. The decks 2x6 PT floor joists are in excellent condition. I figure, given my age, if the PT lasts 20+ years, it may outlast me. And if I last more then 20, the last thing of concern would be a 20 yr old solar system.

While wood is a viable engineering material with lots of advantages, it is often passed over in favor of other materials, usually metals, for solar arrays, depending on the application. Over time, metals often seem to handle deterioration and weakening from vibration induced stresses better than wood, those wind induced vibration stresses commonly being of a larger magnitude for solar arrays than other structures such as fences.

[tyab]

Hello Kuma. As a fellow Cal guy be aware that any structure you do will most likely need a PE stamp for it in your permit package that take into account soil conditions and all expected loads. Many areas want calcs for 100 MPH of wind. The savings of a self engineered mount could easily be lost in engineering fees. Just food for thought as you continue your research.

[Kuma]

Hello Kuma. As a fellow Cal guy be aware that any structure you do will most likely need a PE stamp for it in your permit package that take into account soil conditions and all expected loads. Many areas want calcs for 100 MPH of wind. The savings of a self engineered mount could easily be lost in engineering fees. Just food for thought as you continue your research.

Yes, researched the requirements. Per the County PV Systems code:

"For Ground Mount and Wind Generator Systems Provide:

[ ] Engineering [When the total height from ground to top of the array (not post height) exceeds 6 feet] for mounting, attachments, and foundation to meet the minimum wind and snow loads. Provide details of attachments, anchors, brackets, photovoltaic panels, and all hardware. "

[Kuma]

While wood is a viable engineering material with lots of advantages, it is often passed over in favor of other materials, usually metals, for solar arrays, depending on the application. Over time, metals often seem to handle deterioration and weakening from vibration induced stresses better than wood, those wind induced vibration stresses commonly being of a larger magnitude for solar arrays than other structures such as fences.

Understood, although side loads on fence posts due to horses is worth noting. As is x-bracing and vertical strength. The other consideration for the ground mount is galv. fence posts. With a 30* tilt and not stacking panels, the highest point will be ~ 5.5'.

[J.P.M.]

Understood, although side loads on fence posts due to horses is worth noting. As is x-bracing and vertical strength. The other consideration for the ground mount is galv. fence posts. With a 30* tilt and not stacking panels, the highest point will be ~ 5.5'.

As with any solar design, if you are in CA and follow the rules, the design will need to pass through the AHJ. Part of that process will usually mean review and approval of the structural portion of the design which usually requires a design that was done by a P.E. Such approval can also and usually take the form of standard designs from racking outfits which have limitations stipulated with them for wind, seismic and other types of loadings. If standard, erector set type of racking is used, and as long as the racking is done according to the design plans and is located in an area within the racking mfg. stated design limits, it ought to be OK.

DIY stuff will probably, but not entirely without exception require a design done/stamped by a P.E.

[bcroe]

If the construction is inadequate, it could end up like this. Much less critical than a fence failure, which could release
some of the half ton critters so common here onto the road. This test panel went up on the longest day, to serve for
measurements through the shortest day, which it did. But the stand was left and didn't survive the winter; fortunately
the panel wasn't damaged.

Build what is necessary in your location. That may be tougher where there are hurricanes or the ground shakes. Here
in the Wild West zoned Ag, a 65' radio tower or a fence do not require a permit or inspection. A ground mount is just
another fence. Bruce Roe

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