Ground Screws for a ground mount? Anyone use them?

[Ellis Redding]

I've been considering ground screws for mounting my panels rather than concrete piers.
Anyone use them?
Any issues?
Anyone know where best to buy them?

 

[Rennit]

I just finished my setup about 3 weeks ago. 28 430w Hanwah Q Cell Duo panels going to a Sol-Ark 12k.
I'm in Oklahoma and it's already survived 60-70mph winds according to the weather guys. This particular setup is rated for 110mph winds.
This setup came from readyracksolar.com and came with literally everything you need to mount your panels, including the clamps and everything. Literally the only thing I needed was the panels to have a complete ground mount. (not counting the breaker box shown for about $60).
I paid $4600 shipped DEC21 for the entire kit and it arrived in about 2 or 3 weeks on a crate (last pic with the tractor).

One thing to consider is the kind of soil you have in your area. Here in my area of OK, we have about 18 inches of normal top soil on top of brown STICKY HARD CLAY. This clay was a royal pain in the rear end to get the screws screwed in but my god they are fricking solid once they're in. We had to buy grade 8 bolts to replace the bolts that came with the kit because they would bend and break.. When they bend and break they also tear up the tube and twice the bolt on the screw itself broke, then we had to dig it up and I had to cut off the bad part and redrill it, plus I welded a little extension on it to replace the part we had to cut off. Was a pain in the rear but I don't blame the manufacturer for my soil being really tough. We also ground a cutting edge on the screw. For some reason they came with a blunt edge, but it didn't take much time grind.
We have a 35hp tractor with a post hole/auger attachment but it was not strong enough to drill the screws, had to rent a skid steer with auger attachment. Looking back, I would recommend doing that anyways because the skid steer hydraulics are reversible so if you accidentally screw in the screw too deep or just past square you can reverse the direction.
We didn't exactly get everything set perfectly square so I bought a 2 inch strip of 3/16 metal at Lowes and made some spacers to even up the rail mounts (shown in one pic).

Overall I would do it again. No regrets!

 

[HRTKD]

@Rennit, that's a nice setup with a beautiful result.

I'm surprised to see a ground screw like yours. I attended an Iron Ridge class this year and saw theirs so I was expecting something like that. Here's an image from the Iron Ridge Ground Screw page. It's a good thing you're handy!

 

[MarkSolar]

I used ground screws from Ready Rack. The ones @Rennit used are called helical foundations. Ground screws look like the photo you posted from Iron Ridge. They each work in different conditions. We have really bad glacial till with lots of rocks, so I had to use ground screws. LIke @Rennit I have a tractor that wouldn't even begin to drive them, so had to rent a skid steer to get them in. We have a 42" frost depth, so they needed to be really deep. I think they require 36" of screw beneath frost line, so that makes the whole screw about 7' long. I had a bear of a time getting them in straight because of the rocks. After I installed the verticals I had to strap a few of them to my tractor and "persuade" them to get them in the correct position. If I had it to do over I would have poured a floating concrete slab and anchored the verticals to the slab. It's too hard to dig footings or put in ground screws around here. I think in the end the cost would have been about the same and I would have had a concrete surface to reflect for bifacial panels. If your soil is not bad I think either helical or ground screw would work OK. I was happy with the quality of the Ready Rack product, and price was much less than Iron Ridge. Here's my install:

 

[Rennit]

@Rennit, that's a nice setup with a beautiful result.

I'm surprised to see a ground screw like yours. I attended an Iron Ridge class this year and saw theirs so I was expecting something like that. Here's an image from the Iron Ridge Ground Screw page. It's a good thing you're handy!


View attachment 91207

Cool. Yes, readyrack has something just like that. I gave them feedback on my array after it was installed and they actually recommended if I add on to my current system to use the screws like this.

 

[BrianVeg]

I know this is an older thread, but I’m looking at a Readyrack system and was looking for feedback from someone who has had it for several years.

What do you guys think? Would you do it again?

Thanx

 

[MarkSolar]

I know this is an older thread, but I’m looking at a Readyrack system and was looking for feedback from someone who has had it for several years.

What do you guys think? Would you do it again?

Thanx

I've had mine about 3-4 years now, can't remember which. It's fine, I don't think there's a problem with longevity on any of them. It's really more about making the right choice for your soil type. I mentioned above we're on glacial till and it was a mistake for me to choose ground screws. I'd pour a floating slab if I did it again. You've got frost heave problems like we do so you really can't use ballast blocks because they don't move together. So you've either got to get down below frost line, or stay on top of it and pour a one piece slab.

As an aside, I'm getting ready to install more panels vertically on the wall of that barn behind my existing ground mount. That avoids installing anything and our biggest load is in the winter, so vertical panels should work well. If you happen to have a spare empty wall laying around...

 

[BrianVeg]

It's really more about making the right choice for your soil type.

My soil is pretty much clay. Don’t think i have many rocks. I’d put them up near a vernal pond, so the ground is pretty soft until mid-summer.

Thanx for the input.

 

[MarkSolar]

My soil is pretty much clay. Don’t think i have many rocks. I’d put them up near a vernal pond, so the ground is pretty soft until mid-summer.

Thanx for the input.

I'd talk to the company about your soil. My guess is helical screws might be better than ground screws for clay.

 

[BrianVeg]

I'd talk to the company about your soil.

Thanx - I’ve been talking to them, but I’m getting closer to a decision. So need final info.

Also, I’m close enough to pick the system up!

 

[MarkSolar]

Thanx - I’ve been talking to them, but I’m getting closer to a decision. So need final info.

Also, I’m close enough to pick the system up!

I don't know if you're anywhere near a Greentech Renewables, but I was close enough to one of their warehouses in Chicago to get free shipping. They also had the best prices of anyone I found around here and everything was in stock. They have places in most major cities if you're near one.

 

[BrianVeg]

I don't know if you're anywhere near a Greentech Renewables, but I was close enough to one of their warehouses in Chicago to get free shipping. They also had the best prices of anyone I found around here and everything was in stock. They have places in most major cities if you're near one.

There is one in Detroit, not that far away. I’ve been wanting to check them out for panels anyway.

 

[ricardocello]

I used these, 3 per ground mount in a triangle. Easier than digging, rated for 2" Galvanized pipe (I used 2" Rigid conduit).
No regrets so far. Tricky to drill the 2" Galv pipe to line up with the holes, bough a special jig.
However, I did my own design. In retrospect, a kit would have been much easier.

PE46-Hex8: 46-inch Penetrator with 8-inch extended hex head

Permanent, temporary and mil-spec ground anchors for soil, sand, asphalt and underwater applications. Penetrator screw-type anchors and cabled anchors in arrowhead and bullet style.

americanearthanchors.com