Solar panel mount question.

[ClydesdaleKevin]

Are the frames of solar panels strong enough to be mounted to the roof with brackets at the frame mounting holes, or do I need to construct a stronger frame to wrap each panel in before mounting them?

If I flat mount them with short 4 inch L brackets bolted right to the solar panel frame in the factory holes, at each hole around the frame, it seems to me it would be strong enough to keep the panels safe, and give them more airflow under them.

Someone suggested I need to completely frame off the panels for strength and then use the brackets on that frame...is that true, or is the panel frame strong enough, especially on short mounts?

Kev

[tiinytina]

I would think reinforcements would not be a bad thing seeing as the panels will regularly subjected to 50-60mph wind from driving especially if they were meant to be flush mounted. I would also say putting a piece of plastic or aluminum that would serve as a forward wind baffle would also add to less wind resistance under it while moving forward. 

Tina

[gadgetman]

You use the frame mount hoes  usually 6 for a large panel

[ClydesdaleKevin]

I found these 4 inch tall and about 3 inch wide heavy gauge galvanized steel construction brackets at Home Depot that I think would work perfectly.

So, if I use them at each hole, bolted right to the solar panel frame, then screwed to the roof with putty tape and sealant, it should be strong enough not to have to frame off each panel?

Kev

[DanD2Soon]

Kev,

Buy some of that aluminum angle you were going to use and cut & drill your mounts from that.  The frames of your panels are anodized aluminum and you want to stick to the same type of metal for your brackets.  When I first saw the panel spec sheet pdf. file whose link you posted, I noticed yours have almost identical frames to those that Gadgetman & I are using.  Mine only have four aluminum bracket feet (about 6" long x 3 1/2" high) per panel and are rock solid.  I do think you might consider adding a bracket halfway across the narrow end of yours as they are 3 feet wide where ours are only 2 feet across.

Back to the choice of metals.  Even galvanized steel is going to rust wherever it gets sawed, scraped or "scuffed" and dissimilar metals are going to try to corrode anytime they are mated together in an outdoor environment.

I'm an absolute 'worshiper' of dielectric grease too.  Last bought a 4 or 5 ounce can of the stuff several years ago and I've got plenty left.  Every single electrical connection in my solar system is coated with it.  Battery cable to battery post.  Panel to panel connections on the roof. Every connection on every solenoid post.  Every wire end just before I slip the crimp connector on it.  Years later, I still have no corrosion on my battery posts - none. 

My Panel mount brackets are aluminum but they are fastened to my panels with standard 1/4-20 zinc plated bolts, washers and nuts - every piece was wiped with dielectric grease before assembly and they're still good.  By the way - I put a pad of Eternabond tape under each bracket foot before fastening it to the roof - great seal and just a touch of shock padding too. 

what else? dielectric grease, oh yeah - zip ties, don't cut any of your panel wires until you're sure you're not going to make any more changes - for now (maybe even til you get to winter quarters) just neaten your wiring with zip ties.  good luck - have fun - trust your gut & don't over-think-it - you'll be fine.

[ibdilbert01]

This is an installation we did for a local school used on a marching band trailer.





Being a semi trailer, it had metal struts every 2 feet so we were able to mount the panels to those struts.  The mounts are just 2" aluminum angle, powder coated to match the panels frame.   In the pic below, you can see we left a 1/4" air gap not to trap hot air and or water.







Also a fan of dielectric grease!  If you hate corrosion, dielectric grease is your new friend!

[ClydesdaleKevin]

Thanks guys!  That certainly simplifies things.  I'll get a piece of 3 inch aluminum angle stock, just enough to make 24 3 inch wide brackets...which I can cut out on my chopsaw...the Diablo blade goes right through aluminum nice and clean...That will also leave me 2 inches of air space under the panels.  If necessary though, I could still go with the galvanized brackets and paint them, and use a rubber washer between the aluminum and the steel...with stainless bolts.  That would minimize the disimilar metals reaction.

I like the Eternabond idea, although I'll have to see if the local RV place has any in stock.

The dielectric grease sounds like a very good idea as well.  I'll have to pick some up.

The front panel is definitely going to be the challenge though.  Its going to sit side to side right at the front of the roof, and the leading edge will sit over the fiberglass shell of the cab.  I don't want to drill into that!  If I had access to the inside of it, I could use bolts and rubber washers, but i don't have access, and I wouldn't trust just screws in the fiberglass...plus I would be afraid that wind and vibrations would eventually crack the fiberglass, which would be bad juju.  I'm thinking it might be a better idea for that panel to use the brackets on the back edge and sides, and then on the front edge, use a solid piece of angle stock, bolted along the edge of the panel, but instead of being bolted to the fiberglass cab shell, gluing it down with a high strength adhesive caulk.  Or maybe even glue it down with fiberglass epoxy resin and fiberglass strips...make it a part of the shell, as it were.  As long as its making contact with the fiberglass and glued down, it should be more than strong enough to support the weight of the panel, and the long angle aluminum piece would act as an airdam to keep highway winds from lifting the panel.  I'm also thinking of adding a plexiglass wind fairing to the front of the panel as well.  I might even do the same for the middle panel, which also sits side to side.  Wouldn't have to on the  back panel, since the middle panel with a fairing would block the wind from the rear panel.

Yep, that front panel is going to be a challenge, but I like challenges!

Kev

 

[gadgetman]

if you want to glue a bracket down to fibeglass use 3m window weld urethane, napa sells it and its 15.00 a caulking tube. Or from a glass company for windshiels its about 8.00 a tube but thats not the fast curing stuff. either will work and its some tough stuff. Hope you never have to remove it tho. You would have to cut it off. Its some amazingly strong stuff.


I used air dams on my panels too. I used aluminum, bought a 4/8 sheet of it for 45.00. My neighbor has a sheer and a break   lucky me !!


[smg id=4353]


The ft one is a little hard to see in this pic.


[smg id=4502]

[ClydesdaleKevin]

Looks good!  I'll check into that window epoxy too, although we are right near a bunch of marinas so getting fiberglass epoxy resin and fiberglass would be easy to do.

So does everyone think 2 inches of air space is enough?  The shorter my brackets the stronger the mount, but I don't want these things to overheat either.

Kev

[ibdilbert01]

We tell everyone 1/4 inch is sufficient.   That being said, more can be better as the cooler you can keep your panels the more they will put out.

[ClydesdaleKevin]

So I picked up the solar panels yesterday, and they are awesome!  They are, however, a bit different than what I expected as far as mounting holes.  These are the black framed panels with the special Zep system mounting grooves on the side...fortunately they also have mounting holes under the frame...the Zep feet are 25 bucks each!  And we'd need 8 per panel!  Yikes!

Anyhow, they will have to be mounted with Z brackets as opposed to L brackets.  I found some good deals on eBay for aluminum Z brackets, complete with stainless hardware...40 brackets for 70 bucks, more than enough to do the job.  Supposed to rain all day so I'll probably go ahead and just order the brackets and charge controller, but if I can find Z brackets when I'm out today I'll just pick them up.  I don't recall ever seeing Z brackets at a hardware store though.

The brackets I'm looking at would hold the panels 1 inch off the roof, which is enough according the general concensus...lol!  Still have to figure out a good and solid way to mount the leading edge though...so I'll be running out to the metal shop in Jersey today to see what they have.  They might even have aluminum extrusion that is Z shaped that I could just cut my own brackets out of and drill holes for the bolts and screws...might be cheaper that way.

Also had a question about grounding and wiring, which I will post in a different thread.

Kev

[ClydesdaleKevin]

I ordered enough Z brackets, complete with stainless steel hardware, off of eBay yesterday...after pricing out making my own brackets.  Cost me 88 bucks, but that's still way cheaper than any alternative I found while out yesterday.

The panels have 10 mounting holes each, 3 on the long sides, and 2 on the short sides.

I ended up getting 2 different size Z brackets to compensate for the slight dome of my roof.  The main Z brackets are 1 inch tall, while the ones I'll use in the center of the panels are .5 inch where the panels will sit at the crest of the dome. 

I also pickup up another roll of Eternabond tape to put under each bracket before screwing them down to the roof...and then I'll seal over and around the brackets with silicone.

And I've got a definite plan now for the front panel.  Since the leading edge will sit over the fiberglass part of the cab, and since that edge starts to slope down towards the windshield slightly for wind resistance, I'm going to cut plywood spacers thick just thick enough to screw the mounts to without penetrating the fiberglass.  I'll sand the fiberglass under where the spacers will go, then using fiberglass resin and fiberglass, I'll mount the spacer boards right to the fiberglass permanently and layer up the glass.  Then I'll paint it once the resin sets, and voila, a solid place to mount the front brackets! 

I also came up with an elegant and easy solution for a wind fairing for the front panel.  I'm going to use a fullsize pickup truck bug guard, the kind with the 3M sticky tape on the bottom, and just stick it to the fiberglass on the roof in front of the panel.  It should work fine and look nice too, without any complicated mounts or drilling holes in the fiberglass.

The back two panels will get a much more basic wind fairing, since I doubt the 3M sticky tape would stick to my Kool Seal covered roof very well.  Probably just a short length of sheet aluminum at a slope, attached with something simple right to the Z brackets.

So this coming Monday and Tuesday I should be able to complete the install completely!

Kev

[ibdilbert01]

Can't wait to see some pics!!!

[ClydesdaleKevin]

I'll definitely take and post lots of pictures before we leave to North Carolina in a few weeks.  Been too busy doing the projects, and building catapults, to even take any pics yet...lol!

The tracking numbers for the brackets will get them here in time for installing the panels on the roof Monday and Tuesday, but the charge controller and mc4 connectors won't be here until Thursday or so, so I won't be able to hook them up until the following week.  At least they'll be mounted!  I'll run the wiring this Monday and Tuesday as well, and install the 2 more golf cart batteries for a total of 6, so then all I'll have to do is tie in the wires and controller and whatnot the following Monday and Tuesday.

That's okay though...I'll have more than enough other projects to keep me busy this Monday and Tuesday, like getting the new tires mounted, getting and installing the batteries, etc.

Kev

[wrolandhyattjr]

Kev:

For what it's worth, my Mitsubishi instructions say to allow 3.5" clearance for proper cooling circulation.

[ClydesdaleKevin]

The panels are mounted!  First I cut out 5 4 inch by 3/4 inch pieces of plywood and routered the edges to a 45 degree bevel.  Then I made a frame out of 1x2 pine the exact same size as the panels, marked where the Z brackets go on the panels onto the pine frame, screwed the Z brackets to the frame, and had a template to work with.

Up on the roof with the frame, and I was able to mark exactly where the front panel Z brackets would go over the fiberglass cab of the RV.  Then I sanded away the gel coat and roof coating with 80 grit sandpaper, and using fiberglass resin and fiberglass, I adhered the plywood blocks to the fiberglass cab and let it set for 2 hours.

Then I painted it with Rustoleum white spray paint that said it was good for all surfaces, and the panels were ready to get up on the roof and start the mounting process.

To get these huge panels up on the roof safely without damaging them, we had a brilliant idea since our awning is out.  We wrapped each panel, one at time, in a fuzzy fleece blanket, tied a rope through the upper mounting holes, and layed the panel, panel side down, on the awning.  Then I went up the roof ladder and gently pulled the panel up the awning with the rope.  The blanket protected both the panel and the awning from damage.  It worked like a charm!

Once up on the roof, I attached the Z brackets to the panel.  Turns out the extra set of smaller Z brackets I was going to use can't be used with these panels...what I thought were mounting holes were smaller sized ground holes, and I wasn't about to risk damaging the panels drilling them larger!  I used stainless steel bolts and lock nuts.  8 per panel.

Before I could mount the front panel I had to remove the CB antenna...which was a bear!  I ended up unbolting it from its bracket and cutting the wire, then, since I couldn't even get to the bracket bolts, I used channel locks to bend the bracket back and forth and back and forth until it broke off flush with the roof.  Then silicone, then Eternabond tape...should be sealed forever now!

Okay, the antenna was off, the paint was dry, time to screw down the first panel!  I placed the panel with its already mounted Z brackets over the wood blocks already adhered to the fiberglass shell.  They lined up perfectly.  A piece of Eternabond tape under each of the 8 Z bracket feet, and then I screwed down each foot with a number 12 stainless steel screw.  I used 1 inch screws on the solid roof, and 1.5 inch with the front feet, since it had to go through the 3/4 inch plywood, and down into the fiberglass. Solid as a rock!  I also screwed a ground connector to the panel before mounting, since it would have been hard to do later when I wire them in, and made sure the panel wires were coming out where I wanted them to.  Then I used copious amounts of white silicone on the screw heads and around the Z bracket.

Up on the roof with the next panel using the awning, rope, and fuzzy blanket trick, and I attached the Z brackets and ground connector.  The second panel to go in was the rearmost panel, since the center of the roof, where the third panel was to get mounted, is the only area up the large enough to mount the Z brackets and manuver around, and was also where I had to stand to pull up the panels.  The rearmost panel also got mounted side to side, but I offset it as far over as I could to the passenger side...which leaves me a whole foot to walk around it on the driver's side for roof maintenance and whatnot...good thing I have pretty good balance!  Eternabond under each foot, a stainless screw, silicone, wires positioned, and voila, the second panel in place!

The final panel was tricky, since it pretty much fills the center section of the roof near the fridge vent, and there isn't a lot of room to work around it.  But work around it I did, and it was finally mounted, Eternabond tape, stainless screw, silcone and all!

The mounts are solid as a rock and the panels aren't going to go anywhere!  I only have the 1 inch of airflow under them, but I'm sure that will be more than adequate...and the 1 inch brackets make them nice and low slung to the roof, out of harms way, and very very solid.

Before we leave to North Carolina, I have to make a wind fairing for the front panel, and possibly parts of the back panels, although I think a wind fairing on the front panel would negate the need for ones for the rear panels, especially since the rear panels are already almost entirely blocked by the air conditioner and MaxxAir vent covers.

I ran out of daylight to wire them in, so that is next Monday and Tuesday's project, along with many others.

Kev

[ClydesdaleKevin]

So I found a cheap and elegant solution to my wind fairing project for the solar panels.  While scrolling through eBay listings for wind fairs, air deflectors, and the like, I found a 63 inch wide aluminum wind fairing, made for ladder racks, by Vantech.  I bought a roof rack from them once for my old Astro van, so I know they are pretty good quality.  And it was only 35 bucks, brand new!  It has three sliding bracket locations, so I'll be able to line them up with the fiberglass covered mounting blocks I installed for the panel feet and attach it securely with either the aluminum Z brackets I already have, or else L brackets.  It will be a solid and slick setup, and look nice too! 

Kev

[ClydesdaleKevin]

I got the air foil mounted yesterday, and it should do the trick perfectly...and it looks great too!

First I set it in front of the front solar panel, and marked where the brackets would go and marked them with a sharpee, then set the brackets in place with the little allen key set screws that came with the air foil.

Then I used 6 steel L brackets, 2 short ones in the center and 4 long ones, 2 on each side.  I cut them to fit exactly, drilled some holes in them for mounting, bent them all to the same angle to get the pitch and height of the air foil just right in front of the solar panel, and bolted them to the air foil brackets with stainless steel machine bolts, washers, and lock nuts.  Then I painted them and let the paint dry while working on other projects.

Then some eternabond tape under them, and screwed them down to the fiberglass covered plywood solar panel mounting blocks I already installed for mounting the solar panel over the fiberglass cab.

A liberal amount of silicone on the screw heads and all around the painted brackets, and voila, a waterproof and solid mount for the air foil!

Because of the slightly domed shape of the fiberglass cab, there was still a small 1/4 air gap under the air foil on both sides, and although this probably wouldn't have been an issue, I'm the king of overkill when doing a project right.

Eternabond tape to the rescue!  I used a 63 inch long X 4 inch wide piece of Eterabond tape and adhered it to the air foil and then to the fiberglass cab, pushing hard on the stuff to get it to stick permanently...voila!  Not only is the air gap sealed, the air foil is now Eternabond mounted as well as screw mounted...ain't gonna go anywhere now, and the angle will deflect the air perfectly away and over the panel.  SWEET!

Pictures coming soon!

Kev

[eXodus]

Found something promising:


glue to the roof:


http://brightsolar-power.com/index.php/product/view/138.html







It's something new an chinese, I just wrote to the supplier. Don't know how much this it, but it seems like it could be a nice alternative to making wholes in the roof.

[Rickf1985]

I saw where Tina noted that the panels are sometimes subjected to 60 MPH winds. Think about it, They are sometimes subjected to double that!! Around 120 mph winds when you get a 60 mph headwind gust from another truck or out on the prairie driving into the wind at 60 mph. You pilots out there will know exactly where I am going with this. Ground speed, what is indicated on the speedo plus headwind speed, the speed of the wind blowing in your face. THAT is what everything on the roof of the RV is seeing!!! And none of that takes into affect the crosswinds working on the sides of the panels either. It is a brutal environment up there.

[eXodus]

I would trust a four 3x3 inches glue pads to hold more then the single tiny screws on a z-braket which is screwed into an unknown roofing material.


These glue pads a probably on a metal roof dimensions better then screws, and they are flat so even if you get 120-mph only a very small part of these energy is hitting the panels and the fasting system. Most is deflected.

[gadgetman]

I use urethane, it is the same stuff they use to seal/glue in windshields. The screws are secondary but it needs them too ) Holds the bracket while the urethane sets.

Once urethane drys and it takes hours, you can't pull off a bracket without cutting it off.

Fast set urethane you can buy at Napa. It's about 20.00 a caulking tube and you can't reuse it either. It will dry up in a week or so even sealed once opened. Use gloves too, it is nasty stuff to get off.

[TerryH]

Agree with the above, especially re gloves.
Only problem with urethane is that it is susceptible to UV rays. That is the primary reason for the frit band around the edge of a windshield.
No idea how long it would take to degrade, likely dependant on numerous variables.
Some info:

http://multimedia.3m.com/mws/media/466052O/tds-3mtm-single-step-primer-08681-08682.pdf

Terry

[gadgetman]

Thanks for the info. Yes UV sucks. I don't think it will degrade it under a bracket tho. I have used what's been left in tube to put over cracks in my fiberglass top and I can see the UV affect it but hasn't cracked. I used it because EPDM rubber will stick to it and this fall it gets a new coating.