Solar panels, sikaflex or screwed, unistrut or corner brackets?

[Southdowns]

Hi all,
We have a Fiat Ducato Burstner Nexxo and want to fit some new solar panels. The questions I have are do I just use sikaflex to hold them on or do I also use a self tapping screw?
The other question is, watching YouTube there are many who use unistrut to make a frame for the panel and there are some who use a corner bracket to hold them on. What are the pros and cons?
Thank you

 

[Jimbohorlicks]

We have only ever used sikaflex without screws using the plastic side and corner brackets.Abraided the areas where the brackets go and made sure they were etched/ primed and then applied the sikaflex making sure it was at the required thickness ( tile spacers or matchsticks) and applied when it was warm weather.
Not had any issues but they are a bugger to get off again

 

[Tombola]

Ive used just silka each time, advice as above.
and when Ive seen factory fits they have been just silka too

 

[RustyRuss]

Another vote for sikaflex

 

[peterc10]

Yep sikaflex. If you are screwing in they would not be much good into thin aluminium and would be a potential leak point.

^{_{Subscribers  do not see these advertisements}}

 

[Kannon Fodda]

With the right Sikaflex the adhesive is never going to let go once cured. Only whilst setting is it vulnerable. The concern is the substrate and with some of the flaking paint issues known on Ducatos if a pvc a couple of self tappers may be useful.

 

[Southdowns]

Thank you for the answers guys, that's taken a lot of the guess work out of it.

 

[IRHP]

If it’s only bonding to paint then I’d use screws as well but if going on to gelcoat then the correct Sikaflex will be fine if prepared as instructed. CT1 is also a great adhesive/sealer

 

[Lenny HB]

If using the plastic corner & side brackets make sure you get the correct grade of Sika as not all are suitable. Most of the panels that have come off of vans have been fitted with plastic mounts & the wrong grade of Sika.

I use aluminum brackets with Sika 291i it's a marine grade with twice the holding power of the normal Sika's.

 

[Jev88]

Depends in your roof but I used Puraflex40 on my Coach-built Motorhome. Very similar to sikaflex etc .. and corner feet. Four years and all good. The RV has brackets but then there is a layer of wood up there to bite into along with some similar looking sealant too.

^{_{Subscribers  do not see these advertisements}}

 

[nabsim]

If you contact Sika Tech department they will advise you which is best (or not) for your application. When I fitted mine using the plastic type corner and side brackets they advised me to use Sika 525i or 252i (can’t remember which now) Architectural. Mine was going on a composite coachbuilt roof.

 

[mitzimad]

I've always used allumilium angle to make brackets better surface area than the plastic feet and I use stixal from tool station

 

[Southdowns]

Aluminium angle or brackets sound like a good idea, possibly more surface area contact. I have looked at various sites and there seems to be a choice on what type of sikaflex? 252i is coming up often as an option but also the marine version that Lenny HB is talking about.
I guess I want the safest option but would prefer not to drill holes in the roof.

 

[Lenny HB]

but also the marine version that Lenny HB is talking about.

291i is the marine sealant/adhesive, 292i is the marine adhesive twice as strong as 291i, I used it for my satellite dish.

 

[dash300]

I have 4 big holes in the hull of my boat all sealed with Sikkaflex. I wouldn't worry about a bit of rain!

^{_{Subscribers  do not see these advertisements}}

 

[the1andonly]

I've used puraflex40 from toolstation to fix aluminum angle 40,50mm to a coach built roof . Clean surface lightly abrade and wipe with ipa. SIKFLEX generally need the correct primer. dont forget spacers typically need a 3mm bond line. Check the price. All the correct choices will do the job. Attach panel to Al with rivets or rivets and Allen bolts. When using Al /Stainless Steel interfaces use a barrier layer.

 

[MisterB]

i used 552 in black for my satellite dish and will prob use the same for my solar panels (using abs corner AND side brackets) - have just asked their tech dept in case they suggest 292i as preciously mentioned ....

 

[Stealaway]

Belt and braces on my Burstner factory fit.

 

[TheBig1]

Why is it that people insist on Sikaflex? it is only a brand name for polyurethane adhesive/sealant. Plenty more brands out there without the premium cost. It's a bit like calling all vacuum cleaners "Hoovers"

I have always used aluminium angle cut to lengths for brackets. Clean the area it will be bonded to and mask round the bracket footprint, then lightly sand the surface to give a key for the adhesive. Sand the face of the aluminium too to remove any coating. When applying adhesive, apply enough for a constant 3 to 4mm thick bed over the whole foot and use spacers, like those used when tiling to ensure that the weights does not squeeze it all out.

Once set, the only way to remove the adhesive is to cut through it physically

Many people don't realise that modern vehicle construction uses the same type of adhesive to bond and seal panels. So it really is a super strong bond when done right

The cases we hear of panels flying off roofs is generally poor workmanship, excluding the keying process. Then either the adhesive bond fails or it pulls away a section of badly ahered paint. Sometimes it is down to using plastic mounts that still have mould release agent still on them from manufacturing. Just goes to show the absolute need to sand both mating surfaces before bonding

 

[Snoopy]

Another vote for sikaflex

Same here

^{_{Subscribers  do not see these advertisements}}

 

[Coolcats]

Why is it that people insist on Sikaflex? it is only a brand name for polyurethane adhesive/sealant. Plenty more brands out there without the premium cost. It's a bit like calling all vacuum cleaners "Hoovers"

I have always used aluminium angle cut to lengths for brackets. Clean the area it will be bonded to and mask round the bracket footprint, then lightly sand the surface to give a key for the adhesive. Sand the face of the aluminium too to remove any coating. When applying adhesive, apply enough for a constant 3 to 4mm thick bed over the whole foot and use spacers, like those used when tiling to ensure that the weights does not squeeze it all out.

Once set, the only way to remove the adhesive is to cut through it physically

Many people don't realise that modern vehicle construction uses the same type of adhesive to bond and seal panels. So it really is a super strong bond when done right

The cases we hear of panels flying off roofs is generally poor workmanship, excluding the keying process. Then either the adhesive bond fails or it pulls away a section of badly ahered paint. Sometimes it is down to using plastic mounts that still have mould release agent still on them from manufacturing. Just goes to show the absolute need to sand both mating surfaces before bonding

Interesting one this, if I use double sided tape I use the correct tape advised by 3M sure you can buy other ‘me too’ tapes but have found that they don’t do the same Job. So a named brand with a certain formula range of adhesives has to be a good thing particularly when safety is concerned. Just an oppinion but one based on double sided tapes that have failed yet the 3M ones such as VHB 4941 P is reliable if used as per manufacturer instructions.

There are VHB lookalike tapes out there which are cheaper but they wouldn’t do this.

 

[VXman]

I had mine fitted 'professionally' by Direct Motorhome Services in Nuneaton. They used screws (presumably with some kind of sealant/adhesive) as I found out when the damp check failed, highlighting damp around the 4 feet of the solar panel.

 

[Soots]

If using the plastic corner & side brackets make sure you get the correct grade of Sika as not all are suitable. Most of the panels that have come off of vans have been fitted with plastic mounts & the wrong grade of Sika.

I use aluminum brackets with Sika 291i it's a marine grade with twice the holding power of the normal Sika's.

Thanks Lenny HB used the sikaflex 291i to fix my 2 X 100 watt panels.