Large Ground Mount: galvanized steel or not?

[Shinzul]

Hey all,

I'm about to build a ground mount for my solar array, and I need ~333' of 3" sched 40 steel pipe. It's significantly cheaper to get non-galvanized steel (like, nearly half the price). I'm trying to figure out if I can avoid paying the 2x cost for galvanized steel.

Is this a non-starter? Could you spray paint non-galvanized pipe with something to protect it for cheaper rather than getting galvanized steel?

 

[Supervstech]

Depends on weather, etc… steel pipe will survive a LONG time even unprotected. When we install gas lines, we paint the pipe, it lasts a few years before the sun bakes through and kills the paint. It is supposed to be renewed each year, but SOOOOOO many systems I come to, obviously weren’t ever repainted.

 

[Shinzul]

That makes sense... I mean it's also going to be 100% covered by the panels, so no sunlight would get through. Still exposed to the elements completely, but not sunlight at least.

 

[Mattb4]

Depends where you live. If next to salt water your need all the help you can get against corrosion. Out in the desert plain old uncoated steel will last forever. Most places steel painted lasts quite a long time.

 

[Shinzul]

This will be in the mountains of West Virginia

 

[Bluedog225]

I love galvanized but grew up on the coast and watched the world disolve.

I’d go find a piece of 20-50 year old steel sitting out in the elements. If the corrosion is not significant (structural), go for it.

edit-galvanic corrosion may play a role with solar installs depending on whether you have current leak.

 

[JLBinTN]

Hey all,

I'm about to build a ground mount for my solar array, and I need ~333' of 3" sched 40 steel pipe. It's significantly cheaper to get non-galvanized steel (like, nearly half the price). I'm trying to figure out if I can avoid paying the 2x cost for galvanized steel.

Is this a non-starter? Could you spray paint non-galvanized pipe with something to protect it for cheaper rather than getting galvanized steel?

Black pipe vs galvanized should do fine.

 

[Stephen InGeorgia]

I dont know what the prices are like now, but I chose mechanical tubeing. Its galvanized, high quality stuff used in buildings. Its lighter and thinner than schedule 40, twice the strength and was actually cheaper to get it delivered for my ground mount that buying schedule 40. If you are within 4hrs of a big city see if they have mechanical tubeing and price it out.

 

[Texican]

with you being in oil/gas country you could maybe do what I did in Texas
I used the 3 inch pipe with ironridge system
got my pipe as used oil pipe, very thick wall
used Ospho rust treatment, then rustoleum rusty metal primer then rustoleum gray paint
its been a year and its still perfect
paid $5 per foot cut to length
bought some metal end cap covers thru walmart to keep the wasps out of the horizontals

 

[Bluedog225]

That’s a clean install. 10’ sticks?

And where did you get the caps for the u-bolts?

Thanks

 

[Texican]

That’s a clean install. 10’ sticks?

And where did you get the caps for the u-bolts?

Thanks

thanks, yes the rear posts are 10 ft, with about 3 ft underground, the front posts were just over 6 ft with 3 ft underground,
all the hardware. ubolts caps and rails are all from iron ridge. the horizontals are 32-33 ft
I have 3 mounts like this one

the end caps for the horizontal pipes are thru walmart.com
search for

Jake Sales Brand - 3-1/2” - Chain Link Fence Post Cap - Aluminum​

they are $12 each
$11.95

 

[the_uglydog]

We are in The Philippines. So the weather is hot and very humid most of the year. We used all galvanized heavy tubing with only angle bar that's painted for braces and the actual mounts plus the adjusters. We got some cheap galv. tubes and they rusted in 3 years so we have to paint them, the good stuff has no rust at all. The welds are cleaned and sprayed with galvanizing paint. There's no rust there either at almost al of the welds. They are 3 stories up so there's no shading on any panel, so far they have held up to 5 typhoons and 1 super typhoon. We're building another system for one of our apartment buildings and we plan on putting the same thing on the roof 5 stories up, 3inch galv. tubes welded to the rebar in the concrete. the dog

 

[littleharbor2]

I've noticed when gas pipe is installed by the utility company they wrap it with some sort of black adhesive wrap similar in size to duct tape. I would at least use this for the vertical pipes in the concrete footings/piers.

 

[ricardocello]

https://www.3m.com/3M/en_LB/p/d/v000098361/

Professional tape for this purpose

 

[Supervstech]

I've noticed when gas pipe is installed by the utility company they wrap it with some sort of black adhesive wrap similar in size to duct tape. I would at least use this for the vertical pipes in the concrete footings/piers.

That is a thought.
I wrap buried gas piping, but the exposed part often frays and starts peeling off.

 

[littleharbor2]

https://www.3m.com/3M/en_LB/p/d/v000098361/

Professional tape for this purpose

Thanks.

 

[littleharbor2]

That is a thought.
I wrap buried gas piping, but the exposed part often frays and starts peeling off.

I was pretty much referring to the below grade portion.

 

[Brett V]

The quality of the galvanizing and thickness of the zinc makes a huge difference. I have unpainted galvanized radio towers out there that are 50 years old and show no signs of rust. I've also seen galvanized fence posts from big box home improvement stores begin to rust in a year. Given the high cost of quality steel these days, unless you can score some old surplus stock like Texican did, I'd consider aluminum or wood.

 

[Bluedog225]

Often good, old stout galvanized on craigslist.

 

[glandpuck]

In California, where the ground is often hard and may have granite or clay, the typical ground mount is using 12 inch concrete round casting tubes, 36 inches into the ground. Posts are schedule 40 2 inch galvanized pipe. The pipe portion in contact with the concrete is wrapped in 10 ml PVC tape to prevent contact of the metal with the lime in the concrete. The spacing between the posts depends on the number of panels and height off the ground. Pipes are cut to finish height using portable band saws. Pipes are connected together using Hollaender connectors. If ground penetration is not possible due to rock, then construction of 24"x24"x24" steel reinforced concrete blocks 6 to 12 inches into the surface with the post in the middle are acceptable wind ballast. The rows are attached using pipe cross braces from top of front row to lower end of back row (which should be taller posts than front row) to tie entire structure together. The vertical posts are tied across with more pipe. Then galvanized strut can be used to lay across the rows for mounting of the panels to the strut. Very cost effective, solid, and strong. Key point is to pour concrete around post at least 6 inches above grade and slope it away from pipe for water run off.