Years ago in Colorado I looked at grade beam bases for areas where the soil was poor and not wanting to have to excavate for a massive footing. The Engineering we came up with for a 90 mph three second microburst was 18 pounds per square foot of collector. Please do not take this as gospel, but gives you a starting point if you’ve got an engineer, you’re working with. Best to all of you Sent from my iPad
On May 20, 2026, at 6:53 PM, Zeke Yewdall via RE-wrenches <[email protected]> wrote: I did lots of ground mounts in Colorado -- that was kind of our mainstay, doing jobs that no one else would take (most companies only did roof mounts). We almost never had nice soil to work with in the mountains. Mostly we used multifoot mounts similar to SnapnRack multifoot mount, but usually modified to meet our own requirements. I usually did about 45 degrees tilt, as that was the sweet spot for off grid to shed snow reasonably well, and not kill summer production. I often changed them to mount the modules in portrait, two rows high, rather than landscape 3 or 4 rows high, for less joints to inhibit snow shedding. That involved adding a layer of steel unistrut "rafters" usually. We were dealing with around 55 to 75psf snow load, and 160 to 175mph design wind load. I did all kinds of foundations -- mostly concrete, as we were very often in too rocky of area for the screw in anchors to work well. I did ones with drilled and poured caisons (rare), excavated and backfilled sonotubes, bured footers, buried slabs, on grade slabs, on grade footers, bolted to parking lot bumpers or jersey barriers, or bolted to native rocks. I like the native rocks the best... no need to bring in all the weight or heavy equipment -- if we had a great big granite boulder or granite hillside, we just drilled in 1/2" redheads and bolted feet to the rock. The parking lot bumpers were also good for sites without heavy equipment or concrete truck access as two or three people could drag them up a hill and lay them out, pin them to the ground with rebar driven in, then bolt them all together with a frame on top. The worst ones were where the ground was too hard to dig with a backhoe, but still too soft to get a good rock anchor into -- decaying granite stuff. Those were where I had to just do sheer weight. I had an engineer who would review and stamp all of my custom designs, and as long as I had enough weight, I could do pretty much whatever -- he pretty much only evaluated weight for the caisons anyway. We didn't have expansive soils issues in most the places I was working, so getting below frost depth wasn't a concern, at least. Zeke Message: 3 Date: Tue, 19 May 2026 23:35:21 -0400 From: Howie Michaelson <[email protected]<mailto:[email protected]>> To: RE-wrenches <[email protected]<mailto:[email protected]>> Subject: [RE-wrenches] Ground mounts Message-ID: <CAHMeMsmfQQY_SEnH6EGBrGXj2Qh1RqWb+=-26ih9xeg8l8g...@mail.gmail.com<mailto:[email protected]>> Content-Type: text/plain; charset="utf-8" We have been using Nuance Osprey racking for ground mounts for a few years, with earth anchors for our attachments. Where there's decent, deep enough soul, this system works reasonably well and we don't need to mobilize any large equipment. This is a major advantage when working on more remote systems where the expense and logistics of large, heavy machines is less practical, especially for even larger residential sized systems. Unfortunately, working in northern Vermont doesn't usually afford us "decent" or deep enough soil, so we've struggled a lot with the earth anchors. Additionally, our local supplier of Osprey racks no longer deals with them so sourcing problems along with the installation hassles has pushed me to look for another, reasonably priced ground mount system. So I'm looking for suggestions of racks and attachment systems others have found useful. We are looking at helical piles, but of course they are expensive. If they are our best option, we will price accordingly, but they are not a sure bet around here either. All suggestions are welcomed! TIA, Howie Michaelson Sun Catcher LLC _______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/[email protected]/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
_______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/[email protected]/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
