Under/rear bolt vs center bolt super strut/unistrut


Solar Enthusiast
What do you guys think about this guys unistrut/super strut under mount bolt vs center bolt setup. In later videos he tightens down the under bolts. I like that you could collect rain with no gaps in our desert, but it seems weaker. Each panel would have 4 bolts through the back aluminum housing strip only vs the larger gap with the center bolts and a square washer holding down the panels. I wonder how strong 1/16" aluminum is to tear through to fly away with the under/rear bolt.

I read the aluminum unistrut rails have 350 lb uplift strength with the nuts that are spring or slide in, like this guy has that utilize the lip. I assumed a full center bolt through the chanel with washers on both sides would be better, is that overkill. Would you rear/under bolt them like this guy?

I assume stainless bolts with locking washers would be better vs steel that could rust. Either way you have dissimilar metals.

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Photon Sorcerer
I couldn't make out how he attached them.

I've put bolts through panel frame holes into channel nuts in super strut, for one rooftop project.

Most of my panels are ground mounted with Unirac rails and bottom clips, bolted to panel frame holes.
Strong enough for 15 years of he weather in my location. An occasional strong wind in the fall, but not coastal.

I do have one array with top clamps, utilizing some rails and hardware I happened to have.


Solar Enthusiast
He used the holes in the back of the panels to slide in square nuts. I saw my panels had holes that looked oem.

Okay, sounds like the holes in the back are strong enough. To me his unistrut looked weak. I saw a super strut with 1 inch square that looked way stronger.

Is unirac better? I'll check it out


Photon Sorcerer
Unistrut/Superstrut has gotten into the PV panel game, has top clamps and other stuff.
Obviously shallow channel would bend a lot easier.
Steel channel is heavy, but readily available. I use it more for some structures, usually not for rails.
Aluminum struts are available but I haven't bought any. Stainless hardware is expensive.

Unirac and Iron Ridge both have good mounting systems.
I use Unirac ULA, either standard or heavy-duty rails on 2" pipe frames.
I use bottom clips but they also have top clips for rooftop use.
The hardware is reasonably affordable. They also have grounding/bonding solutions.