Home Solar 2020 Part 4: Uprights and Side Rails

With the concrete footings for the main house frames poured, I set about doing something useful with them - like putting uprights and side rails on!  These are the foundation for the A-frames which I’ve been working on for a while.

This is a companion discussion topic for the original entry at https://www.sevarg.net/2020/08/16/home-solar-2020-part-4-uprights-and/

(Comments from Blogger)

2020-08-16 by Raymond

For driving ground rods, rent a demolition hammer with a ground-rod driving bit. It’s a cupped bit that fits over the end of a ground rod. Commonly used by electricians and amateur radio operators. Renting the hammer will cost you $50-80 bucks for a weekend with the bit.

If the full length of the rod isn’t in the ground, it’s not good enough. Dig a hole and keep it filled with water for a day or so. Keep it filled with water while driving the rod, the water will seep around the ground rod and help soften the earth.

2020-08-16 by Russell Graves

I’ll have to consider that - I need to do some drilling of concrete for the south frames, I may try to borrow a ground rod bit when I do that and kill two birds with one stone. Thanks!

The problem I’m running into isn’t something water will fix. I’m familiar with “stiff” rods that drive slowly, but on a few of mine, I’ve hit a buried rock I can’t break through. The impacts go from “driving it, just not very fast” to “literally bouncing off” - the sledgehammer into the rod becomes an elastic collision. I’ve spent a long while on trying to get those further in and it doesn’t happen.

2020-08-16 by Raymond

The demolition hammer I’m describing is a large electric jackhammer. Weighs about 40 lb and does not rotate. The smaller “demo hammers” that double as hammer drills are not up to the task, IMHO. Lots of yoogle videos on the subject.

The big demo hammer may be able to fracture the rock and drive the ground rod through it. If not, extract it (big locking pliers, then put a jack under them) or cut it off and use another, then start in a different spot.

2020-08-16 by Russell Graves

Oh. Those. Bosch Turbo Brute and crew? I have no idea how I’d get them 8’ in the air to start with.

They’re mostly driven. I have more ground rods than I need, so I figure the net system is probably fine.

2020-08-17 by Sam

I like the site-built beams. Did you end up using stainless screws or other outdoor rated ones, or will you rely on the paint to keep the weather out? Also, you’re probably fine, but generally speaking the structural load shouldn’t be upon the fasteners. They should be present to keep things from moving, but not for holding things up. The surface area on the post base and top is larger than the threads on bolts. Not sure if you have a structural inspection requirement here, but they may not be too happy. +1 on the ground rod driver attachment, BTW.

2020-08-22 by Russell Graves

I’m using either GRK Fastener or Power Pro screws, which are both outdoor and structural rated.

There’s no structural inspection requirement, just electrical. Because the frames are below 7 feet at the tallest point, I don’t need a permit or inspection on them. Practically, each frame weighs in around a ton (with rails and panels), but has 20 5/8" bolts securing them to the uprights (and the uprights to the post bases). My assumption was that the friction between the wood uprights and beams would take most of the load (or the uprights and the post bases), but even if it were just bolts, that’s only 100lb/bolt of shear load. The other option would have been to cut the uprights in place and use more post holders on top, which would have worked, but this seemed like it should be fine. My pretty sketchy initial solar frames out by my office are far weaker and have lasted through some pretty stout storms, so I’m not worried about these.

There are certainly some things I would do differently if I were building them again - but I’ve yet to find a good place to learn about this sort of stuff ahead of time. One of the interesting/frustrating aspects of this project is that I’m doing a wide range of stuff just long enough to start to get a feel for it, and then I’m done.