Anyone familiar with Unistrut?

[Red Squirrel]

Thinking of using Unistrut to mount solar panels on my shed roof. The actual mounting kits are too hard to get and the few sites I found that do sell them here charge an arm and leg for shipping.

So I'm thinking something like this:



How parts come together:



That would give two bolting points into the roof trusses and then the unitrut sits on top for the vertical span, I'd have at least 3 areas where it goes into the roof totaling 6 lag bolts per rail. Would do at least 4 rails, and then 2 or 3 horizontal rails for the solar panels to sit on. Would that be strong enough? We occasionally get super strong wind gust here, and solar panels will basically act like sails.

I found a site that sells Unistrut stuff here (http://www.nedco.ca) , and we actually have a store front for that site here so that means I don't have to worry about shipping. I found the parts I need, but only thing I'm not sure about is the bolts. I can't seem to find them on the site. Would these be a standard part I can just find at the hardware store? I can just bring one of the nuts and then try to find the matching bolt.

All in all does my design seem like it would work? only thing I'm not too sure about is how I will fasten the solar panels to the unistrut, as the mounts are made to go into a drillable material like wood, or decking of an RV etc. i've seen videos of people using self tappers going straight into the unistrut but I don't know if that will be strong enough with the winds we get. I will want to find a way to bolt them in. Not that worried about that part though, I'll improvise when I get there. My main worry is that the mounts going into the roof are strong enough that it won't mess up the roof. What is the best way to seal that as well, just cover it with roofing tar?

Also what is the best way to deal with galvanic corrosion? The different metals such as unistrut, bolts, and solar panel frames may be an issue. Even some of the unistrut fittings have different coatings on them. Like some are hot dip galvanized while some are zinc coated. Will that be an issue?

I'll also want to ground it I imagine, and put in a lightening arrestor, but I'll worry about that once I actually install the panels.

 

[Sukhoi]

Honestly the quantity of questions you have, all of which are good and need answered, indicates you need a professional installation for this job. As an example you clearly have no metals or platings experience and corrosion is a huge concern with something on your roof. I'd be surprised if anything less than hot dip galvanised is sufficient, but don't start mixing metals with your fasteners.

 

[Red Squirrel]

Hence why I'm asking questions, I want to make sure I do it right. I'm not hiring a professional for a shed lol. This has already costed me more than I was planing to spend. I don't even know if any contractors here would do this sort of work, solar is not really a thing here.

I may have to try to find a different source though, the site I'm using seems to have rather limited selection, like idealy I should be able to pick the coating I want and have it all the same across the board but every part available is only available in a certain coating, so that makes things harder. Ideally I probably want hot dip galvanized for everything. Then I only need to deal with the solar panel frames, which I could probably solve by putting rubber spacers or something.

Also just realized that the fitting I was going to use to mount on the roof is crazy expensive. I thought the price was per carton but think it's per single unit. End up spending more on just those fittings than the actual channel itself. So think I will just bolt a short piece of channel straight to the roof (vertical to minimize snow/ice accumulation) and then the long channel on top. Any kind of flashing is probably pointless as no matter what the bolts will be exposed, so probably need to rely on whatever sealant I use, like roofing caulk. That's the part I'm the most nervous about I want to make sure I get the penetrations done right to avoid leaks. It's just a shed, but if I get this right then I know I can do the house the same way in the future.

 

[Sukhoi]

Ah I missed that it's a shed. Thought you were doing your house. I have no knowledge of the mechanics of it all and the forces you are dealing with other than I'd oversize it. I'd do either all hot dip galvanized or aluminum for both the strut and fasteners. You possibly could get away with plain zinc strut with hot dip fasteners but no clue how long the strut will last before it starts streaking rust all over your shed.

 

[Red Squirrel]

Yeah the ones I'm finding a "pre galvanized". Not sure what the main difference is between that and hot dipped. They don't seem to have the hot dipped ones. I can't find the fastners, so I'll have to use whatever the hardware store has. What is the typical finish on bolts at a hardware store? I imagine it must be fairly standard?

I may want to do the house in the future (edited my post with more details before you replied) but this will more or less serve as a test before I go and do that. My main worry is getting the penetrations right and sealed properly as the lag bolt heads will be exposed and I don't really see any other way of doing it. Even the professional mount solutions seem to have a bolt head that's exposed, but it's just that it's designed for that with a seal. Suppose I can do the seal myself with the right product.

 

[Sukhoi]

No, there are usually many kind of finishes on fasteners at a hardware store. What you are probably thinking of as "standard" is electroplated zinc, which is for interior use.

 

[Red Squirrel]

Most of the time they only have one choice too. This might be a pain. That's usually half the battle of doing thing right, actually getting the right parts. I might end up having to just go to Nedco to see if they have more stuff than what is on their site, maybe they'll have the right fasteners too. I hate to do that without knowing 100% what I need or how much it will cost though.

 

[Greenman]

You can get unistrut at just about any plumbing or electrical supply house. But the very first question is, how are you going to seal the roof penetrations? Bolting through a puddle of Karnak will work for a while, but it's far from a proper roof jack.

 

[Red Squirrel]

Yeah I'm open to suggestions on how to go about doing the sealing. I'm thinking something like this? https://www.homedepot.ca/en/home/p.300-ml-all-season-rubberized-roof-repair.1000164498.html

Not sure if that's the right stuff though.

I just wish solar stuff was easier to buy and get. I would just get the right mounts and be done with it. But kind of have to DIY fabricoble something as it's so hard to get the proper mounts.

 

[Micrornd]

Can't help you with sealing the mounts to the roof, but as to fastening the solar panels to the strut, simply use spring-nuts and bolts.
If you are that worried about corrosion, use SS bolts with the spring-nuts.
SS bolts are not that expensive.
And if you are really paranoid, strut and practically all the accessories are available in SS (304 and 316).

Superstrut/Unistrut/Powerstrut/Kindorf (and several other names) are what you are looking for, when you shop for price.
Lowes Ca. sells Powerstrut, I couldn't find it on the Home Depot Ca. site, but since they sell Superstrut here in the States, they probably sell it up there also, maybe just call them and ask.

As Greenman said, any electrical supply house has strut and has, or can get, any of the hundreds of accessories for it.

Look through a catalog -
https://www.unistrutohio.com/unistrut-catalog
Page 148, and also search the document for "roof"

 

[NutBucket]

You can get unistrut at just about any plumbing or electrical supply house. But the very first question is, how are you going to seal the roof penetrations? Bolting through a puddle of Karnak will work for a while, but it's far from a proper roof jack.

I'm pretty sure that's how most of these things are sealed...just whatever generic rubberized sealant is available.

 

[Sukhoi]

Don't use stainless steel fasteners with zinc/galvanized or aluminum strut unless you prefer to maximize your galvanic corrosion. Or can separate the fasteners with nonconductive spacers.

 

[Sukhoi]

BTW what's the reasoning for solar? Lighting? I ran a 16 ft string of LEDs along my shed room and connected them to an 8-pack of NiMH batteries (gives roughly 12 V). Then I wired a real switch into the circuit. So far I've only had to recharge the batteries once after a year of occasional use.

 

[boomerang]

Roof mounts for unistrut at the link. No sealing necessary.

http://solarpowerplanetearth.com/solarsystemhardware.html

 

[Sukhoi]

Did a little more research: https://www.finishing.com/271/67.shtml Due to anode/cathode ratios it sounds like stainless steel fasteners with aluminum strut would probably work fine though it would still be best to separate them with something nonconductive.

 

[Red Squirrel]

Roof mounts for unistrut at the link. No sealing necessary.

http://solarpowerplanetearth.com/solarsystemhardware.html

I found all sorts of stuff like that, but most of these sites don't offer a way to buy it, or if they do, the shipping is through the roof. Most are in the states too. I guess I'm one of the few only idiot enough to play with solar in the north. Nobody really sells solar stuff here as it's super niche.

The goal is for lights, and possibly other uses. It will also act as a source of backup power. I could run at least basic things off it. I'll probably run a feed into the house at some point if I feel I have enough excess power.

I wonder if Nedco can special order stuff that's not on their site though. I might just have to go and ask. I hate going to places like that without knowing 100% what I need though. Those places are more for contractors.

Another thing I'm thinking of is maybe just mounting them to the wall then I don't have to worry so much about roof penetrations. ,Since they'll be facing west it will actually be more optimal to have them vertical, and in winter they won't get full of snow. Only thing is they might be too low. Shadow from neighbour's house will block that area in winter, more than likely.

 

[Red Squirrel]

So I found a solar site in Canada that actually has a buy option (http://www.modernoutpost.com/) , and that does not charge for your virginity for shipping. So bought 8 flashing mounts (they were kind of pricy, like 27 bucks each so figured 8 would be enough and don't need 12). Also for the actual frame I did indeed decide to go Unistrut, I was starting to debate on if I just do wood, but I was worried the wood warps over time and it causes the panels to warp too, and then possibly crack.



I managed to fit 5 10' lengths of it in my 2004 Alero. I should get a truck as my next vehicle... lol.

Now I don't think these are hot dip galvanized I think they are just pregalvanized, will I be ok with using these outside or should I paint them? Or can I just coat them with some kind of oil or something, and will that also prevent galvanic corrosion if some of the hardware is not the same type of metal? The sales guy that sold it had no idea about the type of metal the different fastners are etc. Also had to buy the bolts at Home Depot since they didn't have them so I can't guarantee these are all going to be the same type of metal. Honestly it's something I've never even considered myself for any project, just kinda thought of it for this one given it will be outside so it's probably more likely to corrode if I don't do it right.

 

[Red Squirrel]

Finally got around to doing this.



It's rain season here so it's hard to find days to get stuff done outside but it's pretty much ready for the panels. Still need to do all the inside wiring as I want to build a proper insulated cabinet for the electronics and an insulated battery box with some kind of hydrogen venting that goes through a small HRV (to retain heat). Might need to put a small heater in there too but I'll see. If it's insulated well enough the charging might be good enough.