Solar panels and Sikaflex for Caravans; is it a good idea?

A little while ago someone shared some photos of their newly installed solar panels on a caravan on social media, and the comments section blew up. The photos clearly showed that they were installed using Sikaflex only, and were quite detailed in what process was followed and how it was done.

It didn’t take 2 minutes for the comments to roll in about why there was no screws, or bolts, or secondary fixings in place. A heap of people jumped on board and said ‘3 people were killed in Tasmania recently when a solar panel came off’ and so on and so forth.

It seemed that the vast majority of people were against the way this panel was installed, except for a tiny handful who had experience with the product, and knew what it was capable of.

For me, I hold this topic of discussion close to my heart as we had a solar panel come off our hybrid camper trailer (not installed by us), and I spent a fair bit of time working out why, and how it could be avoided in the future.

I then just recently installed 600W of solar panels using exactly the same method; aluminium angle and Sikaflex 252, and that is it. The above link goes into extensive detail on how we did it, and I’m really happy with it.

Sikaflex peeled off on our hybrid camper
Our hybrid camper lost a solar panel that was installed by someone else

The panels are rock solid, and I’m sure our camper trailer roof would come off before they did, but wanted to address a number of thoughts that were raised.

Primer on the roof
Our new 3 x 200W solar panels are held on by Sikaflex only, and I’m perfectly happy with it

Sikaflex is a worldwide, industrial grade adhesive product

Sikaflex is a massive, massive company, and their product is used all over the globe in thousands of different applications.

There are caravans that are virtually held together by Sikaflex, skyscraper windows held in place, panels of cars and so much more.

When used correctly, Sikaflex is significantly stronger than a mechanical fastening process, and it has a number of benefits over mechanical fastening too.

I’m very familiar with using silicon and Sikaflex, and can tell you that if you stick a piece of metal down correctly you will be struggling to get it off with hammers, screwdrivers, chisels and pry bars.

You literally need to resort to using knives and angle grinders. It is insanely strong, and when you spread this over a large surface area the results are an almost bulletproof setup.

Sikaflex 252
Sikaflex used properly is a truly unbelievable product

Sikaflex do not recommend using mechanical fastening in conjunction with their product

When we did our 600W solar panel installation, I made contact with Sikaflex, and they came back with a very helpful reply explaining how the panels should be installed.

In it, they specifically said that they don’t recommend using any mechanical fasteners in conjunction with their product, and that if you do use them they should be put in after full curing of the Sikaflex (5 days).

How many solar panel installers for caravans do you think wait 5 days before they put screws in? I’d say probably less than 1%, and given most fit them in a day and hand the van back its physically impossible.

I assume that the mechanical fasteners interfere with the Sikaflex’s ability to flex as needed, and if you install them prior to the full cure they’d also affect the bond.

Lifestyle Camper Trailer
Sikaflex themselves do not recommend using mechanical fasteners with their product

The best product in the world will not work with the incorrect installation process

Sikaflex is an amazing product, but if you use it outside of its design scope, or you skip a few steps of the installation, is it going to work properly?

Absolutely not! I was surprised at how detailed and time consuming the process is for installing Sikaflex 252, which involves mechanical roughing, a cleaning agent, then a primer, and then the Sikaflex in specific quantities, time frames and methodologies.

I guarantee you most solar panels that are installed skip half of those steps, and people just whack the Sikaflex on with limited preparation work. Most of the time its fine, but if it’s not?

In our very own solar panel failure (we didn’t install it), Sikaflex was used, but you can see clear as day that it didn’t adhere to the plastic solar panel mounts (which are nothing short of garbage in my opinion).

This could have been due to the incorrect product, or preparation procedure (no roughing of the plastic) or a million other things, but it proves that a great product can be very subpar when not used correctly.

Sikaflex peeling off
You can see clear as day that it didn’t adhere properly, because it wasn’t done correctly

In the recent deaths from a flying solar panel in Tasmania it was also Sikaflex 252 that failed, but no more information was given.

It’s most likely that the failure was induced from the installation process, and not from the actual product failing, but I don’t have the facts to comment for sure.

The deaths in Tasmania were tragic, but the inquest tells a lot more of the story

Last year, a solar panel came off a caravan, and not long after 3 people were killed in Tasmania. It was a shocking result, and a serious reminder for people to check their caravan solar panel installations, but reading through the coroners report highlighted a whole heap of factors that contributed to the tragic result.

I don’t want to take away from what happened, but there are some facts that people overlook when they reference this.

The principle reason for the deaths was cited as the driver reacting poorly due to having drugs in their system.

Another major contributing factor was that seatbelts were not being worn by some of the passengers, which could have hugely reduced the damage

It was of course noted that the solar panel played a big role, and if it had never come off the caravan then the accident may not have happened. 

Of course, I don’t want to take away from the tragedy, and it could have been avoided, but you should know there was a lot more to the story than a solar panel coming off a roof.

Some solar panels are very poorly installed

I’ve heard and seen plenty of very sub-standard caravan solar panel installations, and it doesn’t surprise me to hear of hundreds of solar panels on the side of the roads of Australia.

I mentioned above that the process for correctly gluing solar panels on is substantial, and there is no way that everyone follows these to a tee.

I’ve heard from people that their panels are adhered just with normal silicone and a couple of screws, which is very average indeed.

Solar panel on a rooftop tent
Solar panels can be heavy and very dangerous, so they need to be well mounted

Screw and glue is recommended

The caravan association recommends that solar panels are screwed and glued, but there are no laws or standards that tell you exactly how it should be done. A screw through a thin roof that doesn’t go into anything structural is as good as having nothing there at all.

If you rivet, or screw the panel fastening into a sub structure, it is worth while and can provide some additional support, but it will reduce the amount of flex that the adhesion product has which isn’t always a good thing, and it creates another point where you can have a leak.

More holes means more chance of water ingress

One of the largest causes of damage to vans is water ingress, and it’s a known fact that the more holes you make, the more likelihood there is of water ingress.

The common setup is to screw or rivet it down, and then to put a dob of silicon or sealant over the top, but over time with the UV damage and things moving its entirely possible for water to make its way into your van, and by the time you notice it can have done hugely expensive damage.

Sikaflex done correctly is strong as

I decided not to put any mechanical fasteners on our solar panels, and instead followed the OEM instructions to the tee, with aluminium angle blocking all air flow that is trying to lift the panels, along with having a huge amount of surface area glued down.

I honestly don’t think you’d be able to remove our panels without cutting the sealant off, and have complete confidence in them. If I didn’t, they wouldn’t be up there.

Sikaflex thickness
We followed the Sikaflex manufacturer instructions to the tee, and went overkill on the angle used, and surface area covered

Check your solar panels

If anything, I want to encourage you to grab a ladder, and to have a good look at your solar panel. Give them a wobble and a shake, try and lift them a bit, and ensure there are no weak points, places for water to pool and enter and that no corners are lifting, or losing their strength.

We’ve had enough solar panels come flying off Caravans and RV’s; hop up and check yours today, or get someone qualified to do it for you. Please.

Powered by lots of solar panels
Get someone to check your solar panels, or do it yourself, please!

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  1. Hey Mark,

    Sounds solid, and I like the modular approach for future proofing. I would watch the screws don’t come loose, but maybe a dob of silicon would stop that.

    Our 50×50 angle gives us about 25mm gap under the panel frame, and more from the panel itself, which I feel is enough.

    Cheers for your comment, and thoughts

  2. I used a 40 x 20 box alloy frame setup on the caravan bonded to the Stryomax fibreglass roof with T-Rex adhesive. No screws used. The rails are around 2M long and lay on the 40mm face so plenty of surface area bonded. The roof surface and rails were scuffed prior to bonding. 5 x 200w panels were then screwed using 25 x 25 alloy angle to the rails. This rail system is flexible so if a panel or panels need to replaced and are a different size the rail system allows flexibility. It also provides the necessary air gap under the panels.