Solar panel bonding?

[agb83]

Hi -

A small piece of practical advice from this community would be appreciated.

I am about to install 3 Victron 215w panels to the roof of my motorhome. It’s a 2020 roller team. I have already made appropriate brackets from 50x50 aluminium angle and dry fitted. All other aspects of the project I am comfortable with - including roof prep work, light scuffing etc. The main question is around which bonding product to use. I have several people recommend OB1. Others Sikaflex 522. I am not adverse to using the sikaflex but it’s twice the price of the OB1.

Is the sikaflex the only option, or is the OB1 also OK?

Thanks in advance.

 

[Jev88]

Puraflex40 from Toolstation - made by Sika too! Don't mash the panel down and squirt all the sealant adhesive out - some add 2 or 3mm plastic washers here and there to achieve a nice thickness of bead.

Five years and all still in place and that was the corner plastic feet style.

 

[agb83]

Thanks a lot. Clear on using 2/3mm tile spacers/washers.

The panels I have are 1580mm long - so I wasn’t comfortable with “just” using the 4 corner plastic mounts. Two panels will run along the front to back - with aluminium angle brackets running all the way along the narrower front and rear facing ends. I’ve then put around 850mm aluminium brackets along the left/right side. This should allow a decent amount of water/airflow underneath the panels. The final panel is along width of the roof. Decided to put angle brackets along the full 1560 width. Much smaller 300mm brackets at the left/right side…

 

[headlight]

Thanks a lot. Clear on using 2/3mm tile spacers/washers.

The panels I have are 1580mm long - so I wasn’t comfortable with “just” using the 4 corner plastic mounts. Two panels will run along the front to back - with aluminium angle brackets running all the way along the narrower front and rear facing ends. I’ve then put around 850mm aluminium brackets along the left/right side. This should allow a decent amount of water/airflow underneath the panels. The final panel is along width of the roof. Decided to put angle brackets along the full 1560 width. Much smaller 300mm brackets at the left/right side…

Besides using tile spacers some people also drill holes along the length of the aluminium angle foot to allow the Sikaflex to "mushroom " through the holes to improve bonding even more.

 

[Guigsy]

The plastic feet have quite a lot of area. And it's the corners that'll have the highest loads, so having more area there will make it less likely that peel up. Plus, most of the adhesives bond to plastics better than metals. So I'm not convinced ally angles are better for coach build roofs.

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[tonka]

Another vote for Puraflex 40. Used it on a few panel installations over the years and a sensible price from Toolstation.

 

[MisterB]

Another vote for drilling holes for the mushroom effect !! I used Sikka as I also wanted peace of mind, though I am sure there are very good alternatives available. I also just used the corner and side plastic feet mountings but fastened the panels to the feet using roofing screws. I check them every now and again and never had a problem. I think the fibre washers take up any vibrations but whatever you use, check them regularly!!!

 

[Lenny HB]

I always use Stika 291i, a bit more expensive but higher bonding strength.

 

[Wildbill]

I just use tiger seal never moved on my last van in 9years
I used 2inx2in approx by 2ft long x4 bit over engineered but never moved
Wb

 

[treblid]

I used Sikaflex 291i. As Lenny HB stated, it's more expensive, but higher tensile strength. It's not something I want to economise on as it's safety critical.

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[treblid]

Just to add, I used 4mm slices of silicon tube to act at spacers to provide the optimum adhesive thickness and prevent compression of the adhesive when placing the panel brackets down. I used silicon because Sikaflex is flexible and using any form of hard spacer could provide a difference in boding strength/flexibility that could lead to a long term week point.

I didn't bother with drilling holes in the brackets as a few small thin bodied mushroom heads are not going to make any difference if that's the last thing holding it on at 70mph!

It's more important to abrade both surfaces and clean with a non residual deposit solvent such as IPA before applying the adhesive.

 

[RogerIvy]

Because we fit panels for a living we asked Sika what they recommended.
They recommend 552 as the best.
522 is also very good, a casual observation is that it may set slightly faster than 552 when below 5degC
552 is more pricey than 522

 

[grasscutter]

I’ve used CT1 on my last two vans.

 

[Manic]

I bought panels and brackets off Techno (rip) and he had fitted dome headed screw to the
brackets to act as spacers to give correct bed of sealant.

 

[Revolvor]

Advice from Sika, Posted Previously:

I used 50x50 aluminium angle and sika activator.

Post in thread 'Lost a solar panel' https://www.motorhomefun.co.uk/forum/threads/lost-a-solar-panel.286972/post-5698922

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[stevewagner]

Done quite a few over the years. Always used Sikaflex including their cleaning fluid. I use tile spacers. And lots of weight on the panels overnight. Never had an issue.

 

[eurajohn]

Some while ago I posted This in the tips and tricks section, it is a comprehensive guide to the subject, it is in German but Google translate will make it understandable.

 

[gus-lopez]

Puraflex40 from Toolstation

I've used this also.

 

[agb83]

Thanks to everyone for your responses. I’m going to switch a sikaflex product. Most likely 591 as it’s what I can easily get my hands on. Two questions:

1. It’s stated as a marine product vs caravan/automotive. I assume this doesn’t matter?
2. Is there a difference between 591 and 591i. If so, what and does it matter?

Thanks!

 

[agb83]

Thanks to everyone for your responses. I’m going to switch a sikaflex product. Most likely 591 as it’s what I can easily get my hands on. Two questions:

1. It’s stated as a marine product vs caravan/automotive. I assume this doesn’t matter?
2. Is there a difference between 591 and 591i. If so, what and does it matter?

Thanks!

Ignore me… that should read 291

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[Alanf75]

If using Sika 552 is it recommended to use the primer and/or activator given it requires minimal prep?

 

[Revolvor]

If using Sika 552 is it recommended to use the primer and/or activator given it requires minimal prep?

I still used the Sika activator, as an added precaution.

 

[Alanf75]

Sorry for hijacking with another question - is there any recommendations for UV stable truncking to run the cables in? Is the standard mini truncking adequate or are there better solutions and is it a case of using the attached adhesive or bonding it down with Sika?

 

[Richard n Ann]

Sorry for hijacking with another question - is there any recommendations for UV stable truncking to run the cables in? Is the standard mini truncking adequate or are there better solutions and is it a case of using the attached adhesive or bonding it down with Sika?

I used standard mini trunking, I left it short with the ends open so it dries out. I stuck it down with sikaflex 522. The double sided tape is crap.

Been OK for 7 years so far

 

[MattWithMoho]

Alanf75 - I used mini trunking the same as Richard n Ann .... Screwfix, although I have found the trunking adhesion ok without sikeflex

https://www.screwfix.com/p/d-line-pvc-black-micro-trunking-16mm-x-8mm-x-2m/166ra

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[Alanf75]

I've got some trunking without adhesive so I'm going to stick it down with Sika

 

[the1andonly]

Another vote for Puraflex 40. A sensible price from Toolstation. 2-4mm bondline important, tile spacers or washers a good way to maintain it. Surface prep a vital stage. roughing cleaning and final IPA wipe. I bond in the front to rear direction, if <1m wide no front bracket. if front width 1.6m then use 200-500mm long bracket.

 

[Lenny HB]

Ignore me… that should read 291

I always use 291i never had any problems with it.

I've got some trunking without adhesive so I'm going to stick it down with Sika

I always do than then after fitting the cables I fill the ends with silicone so it's easy to get the cables out if needed.

 

[seanmc12]

Hi -

A small piece of practical advice from this community would be appreciated.

I am about to install 3 Victron 215w panels to the roof of my motorhome. It’s a 2020 roller team. I have already made appropriate brackets from 50x50 aluminium angle and dry fitted. All other aspects of the project I am comfortable with - including roof prep work, light scuffing etc. The main question is around which bonding product to use. I have several people recommend OB1. Others Sikaflex 522. I am not adverse to using the sikaflex but it’s twice the price of the OB1.

Is the sikaflex the only option, or is the OB1 also OK?

Thanks in advance.

I watched a pro company on YouTube they used OB1 and held down aluminium angle with tile spacers to give 3mm gap . Also prepping surface with light abrasive on A/B type mh. That's my choice

 

[Garry - June]

Bit late but just to give a shout to another product nobody has mentioned... Tec7.... I have used this for bonding panels and hatches to my van and also used it years ago when we had a boat for bonding seals to the hull and these were permanently submerged in sea water ... never ever had a seal or join fail in all that time... brilliant stuff.

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