Replacing a lost solar panel on a pop top - advice needed.

[Ayjay]

My apologies in advance for the length of this post but I thought it was necessary to give a bit of background as well as asking for advice. Firstly, here's the pictures:




As some will already have read in my post about our recent trip to South of France, the 160W flexible solar panel decided to go for an impromptu flying lesson from the West Dubs pop top while we were driving down a French motorway at 70 MPH – luckily there was not many cars on the road and I don’t think there was any further consequences behind us. I had always thought that it was stuck down with Sikaflex but looking at the residue on the roof, I now see that it was actually double-sided tape that was used. I’m no expert but I think we got lucky in that there does not seem to be any actual damage to the roof. Indeed, even the two small holes that the installer drilled for the cable to go through have retained their waterproof integrity. We didn’t get much notice of it happening apart from a short burst of noise on the roof followed by a thump as it came completely away and ripped itself free of the cables and junction box which stayed behind – I subsequently cut the wires about ¼” out to try to tidy it up and stop it all flapping about in the wind.

After that, we had to drive a little while before finding a safe place to pull over and that happened to be under a bridge which then allowed me to climb onto the concrete crash barrier and have a proper look. Unfortunatey, I was so shocked at what I saw that I didn’t think to take a picture but I can say that it looked as in this photo except that there was a large piece of black plastic spacer still stuck to the roof down the ‘central channel’. The front of it had already started to come away from the double sided tape and had I been able to climb up on the roof, I would probably have tried to pull it off completely but that would have been difficult. In any event, we started off again and that too went flying.

Looking at what remains, there is a piece of the spacer remaining (on the left hand side in the first picture and right side in the second) and I suspect that it was the upper face of the double sided tape between that and the solar panel that came unstuck which allowed the wind to get under it and rip the rest off (but, as I say, I’m no expert).

Although I have only contacted the firm that fitted the panel by email, they have already given me a positive response to sorting the issue out and I’ve no reason to disbelieve tham as they are a local(ish) outfit with a good reputation in the local VW community. However, a part of me is a bit worried and I suspect that if tape is used again, I will spend all my time driving and thinking that the same thing might happen again.

From reading various posts here on T6F and elsewhere on line, I seem to have the following options for a future panel (excluding using a free standing portable):

Double sided tape. As mentioned above, I don’t think I could ever trust it again.

Sikaflex 512. This seem to be the favourite. I also have a nagging worry about getting the stuff off if the panel ever has to be replaced.

Bolt / screw it down. Would have been the favourite were it not for the fact that it involves drilling more holes in the roof. I am also conscious of the fact that solar panels can fail and if it ever needed replacing, the fixing hole in the next one would be unlikely to be in the same place and then even more holes in the roof would be needed.

Velcro. I know that some on here would advocate using Velcro but for me it’s a non-starter as I simply wouldn’t trust it and I’m not sure that I could ever be persuaded otherwise.

As I have already said, sorry for the length of this post but I should be really grateful for any advice on the fixing methods above and whether I have missed anything else or, indeed, any other comments and advice. I’m going to see the installers early next week and want to ensure that I’m properly prepared beforehand.

 

[Nigel W]

Welcome home.
I had/have similar fears and when I coupled this with we always try to park under trees so are always in the shade and are out of the sun we decided that a suitcase panel would be the best option for us.
I bought the Renogy ones and they are superb which I plug into a mppt controller fixed next to the battery using a long cable so I can position the panels anywhere that’s in the sun and out of the way.
when travelling they have a sturdy case and we just chuck it on the floor.
when parked up at home I just stick the panel on the bike rack.
Just a thought as it’s just so simple, easy to replace/upgrade and being in the sun can be smaller.

 

[DXX]

Sikaflex 512. This seem to be the favourite. I also have a nagging worry about getting the stuff off if the panel ever has to be replaced.

I have a slimline flexible panel. When it eventually fails I plan to stick the new one over the old one.
The adhesive that was used on your van plainly hasn’t worked on the panel and probably wasn’t helped by the gap under the leading edge due to the ribs on the roof.

 

[Dilbert]

That was a nasty experience.

I wonder if the lack of sealant on the front edge contributed to the panel lifting and getting ripped off?


As far as removal of Sikaflex is concerned, I used a 'cheese wire' kit normally used for windscreen removals. It was surprisingly easy to cut through the adhesive beads with 2 people sawing across under the panel. I then cleaned up the residue adhesive with a window scraper and brake cleaning solvent.

You will be lucky if you can remove it without damaging some paint but that will not matter if you are refitting a similar size panel.

 

[Eclipse Custom Vans]

Hi, is that adhesive or double sided tape used on your van, looks like tape? Don’t think I would use tape…..

Generally you need to use a polyurethane bonding agent, Sika etc. Some adhesives do need a primer to adhere to some surfaces as they will stick but just peel off once cured. You would need to check with the manufacturer. I would use primer with Sika on a solar panel.

However, we do actually use a ‘non primer’ adhesive from Henkel for solar panels and have not had a problem.- Adhesive

Good luck,
Ian

 

[Ayjay]

@Nigel W. Cheers for the suggestion. I have thought about a portable set up in the past but I just don't think it would work for us (and I use a tow bar rack as well which is not permanently mounted). The roof mounted panel was good for us for as long as it lasted and my decision is really around whether to have one at all or how to fix it if we do. That said, I have always had in mind that one day we might add a portable panel to a fixed system if circumstances dictated.
@DXX. It hadn't really occurred to me that a new panel could juts be stuck straight onto a failed one. Good idea which would make life a bit easier.
@Dilbert. I suspect you might be correct in that an exposed leading edge wouldn't have helped. but there would only have been some very small gaps. Hindsight tells me that a strip of quality gaffer tape might have been a good idea (but then again, gaffer is my fix for a lot of stuff).
@Eclipse Campers. As mentioned in my original, it was tape - lesson learnt. I must admit that I have never heard of Sika being used with a primer before. That said, I'm shocked to see that the primer is a lot more expensive than my gin of choice (Tanqueray which is not the cheapest on the market).

Did anybody else use a primer when sticking a panel down with Sikaflex please?

 

[Skyliner33]

If i do one again it would be velcro again with sealant to seal the leading edge.
I also wouldnt fo it on my own again as i put it slightly off square (by a few mm or so). I coulfnt get it off yo straighten it even when i climbed on the roof.

 

[Eclipse Custom Vans]

@Nigel W. Cheers for the suggestion. I have thought about a portable set up in the past but I just don't think it would work for us (and I use a tow bar rack as well which is not permanently mounted). The roof mounted panel was good for us for as long as it lasted and my decision is really around whether to have one at all or how to fix it if we do. That said, I have always had in mind that one day we might add a portable panel to a fixed system if circumstances dictated.
@DXX. It hadn't really occurred to me that a new panel could juts be stuck straight onto a failed one. Good idea which would make life a bit easier.
@Dilbert. I suspect you might be correct in that an exposed leading edge wouldn't have helped. but there would only have been some very small gaps. Hindsight tells me that a strip of quality gaffer tape might have been a good idea (but then again, gaffer is my fix for a lot of stuff).
@Eclipse Campers. As mentioned in my original, it was tape - lesson learnt. I must admit that I have never heard of Sika being used with a primer before. That said, I'm shocked to see that the primer is a lot more expensive than my gin of choice (Tanqueray which is not the cheapest on the market).

Did anybody else use a primer when sticking a panel down with Sikaflex please?

Yes, primer is not cheap, but the job needs to be done correctly with correct products. We do however use a non-primer system as I said.

Sika is a good adhesive but many other products out there. Most people are not aware of such products and will have success without primers but we always go with manufacturers recommendations, as a business we could not risk future problems. Sika may not recommend primer but believe me, the world of adhesives is massive with many products for specific jobs, fibreglass, metal, bare metal etc. There are also generic bonding agents. Just depends what you want to use, your van etc. We use what we use and never had a problem.

All the best,

Ian

 

[Ayjay]

@Eclipse Campers. A belated thanks for your input.
Everybody else - I've got to go and see the panel installers next week and just wanted to ask again if anybody (apart from Eclipse Campers) used a primer when sticking a panel down with Sikaflex please? Indeed, I should still appreciate any other comments as well.

 

[andys]

I fitted my 250W semi flex Photonic’s Universe panel in summer 2017 and, after advice from an engineer friend, didn’t use Sikaflex but an MS polymer adhesive. I used no primer and didn’t key the surface of the poptop, but I did clean the roof and the underside of the panel followed by a clean with IPA (not beer). I had the added complication that my roof lifted from the back so I didn’t want to seal across the front in order to allow any water to drain out when the roof was lifted. To do this I sealed the sides with the adhesive, sealed the back, leaving gaps, laid down lines of adhesive about 100mm apart running longitudinally and then squiggled the adhesive in wavy lines between the straight lines. This allowed air and water to pass through from the front or the back.
I recently sold the van and the panel was as solidly stuck down after 4.5 years as it was when I first did it, and the performance from the panel had not reduced at all, producing over 1kWh a day in the Scottish highlands in July.


I’m not saying dont use Sikaflex or don’t use a primer, just saying what I did and that it worked. Good luck.

 

[andys]

I’ll add that I’ve been sufficiently convinced with the success of the method I used that I’ve just used the same adhesive to mount the twin 170W panels on my new van

 

[slocumjoseph]

I’ve been making notes of all the advice as about to fit a 180w Flexi panel to the roof of my pop top. I particularly like the idea of the adhesive pattern as I also have a rear raising roof and hadn’t given a lot of thought to drainage when raised. I intend to fix a Z shaped strip across the leading edge, like the wall rails used for storage bins, as a belt and braces solution to keep the wind away from underneath. @Andy has made me conscious of a potential blockage so I’ll drill little drain holes all along the strip.

 

[andys]

I’ve been making notes of all the advice as about to fit a 180w Flexi panel to the roof of my pop top. I particularly like the idea of the adhesive pattern as I also have a rear raising roof and hadn’t given a lot of thought to drainage when raised. I intend to fix a Z shaped strip across the leading edge, like the wall rails used for storage bins, as a belt and braces solution to keep the wind away from underneath. @Andy has made me conscious of a potential blockage so I’ll drill little drain holes all along the strip.

View attachment 132206

I only needed the drainage gaps at the front as my roof tipped up from the back so that the front was then the lowest point. You shouldn’t need to do this if your roof is higher at the front as the water will drain the other way, I haven’t in my latest van that opens like this

 

[Dilbert]

You need to very careful where you leave gaps. Our old panel had a gap at the rear only as the pop top hinged at the back. Logical you would think.

The problem, however, we had was when it was down. If your suspension is setup correctly the attitude of the van means the front is slightly lower. The rain will then enter at the rear gap and fill up the pocket underneath the solar panel. In winter this can then freeze and damage the panel. The level of your parking area will also affect this too.

On the new panel I have now only completely sealed the front edge and sat the panel on 4mm adhesive beads that run across the width of the panel at regular intervals with a gap in the centre of each bead. The sides are open. The rear has a central drain slot.

This aids ventilation as well as easy drainage. The thicker beads allow for the different expansion rates of the panel and the roof substrate. You need to select an adhesive that has the elasticity and strength to do this.

 

[slocumjoseph]

I only needed the drainage gaps at the front as my roof tipped up from the back so that the front was then the lowest point. You shouldn’t need to do this if your roof is higher at the front as the water will drain the other way, I haven’t in my latest van that opens like this

My roof is the same as yours..lower at the front. That's why your post about the fixing and drainage was relevant to me.

 

[andy greenwood]

You need to very careful where you leave gaps. Our old panel had a gap at the rear only as the pop top hinged at the back. Logical you would think.

The problem, however, we had was when it was down. If your suspension is setup correctly the attitude of the van means the front is slightly lower. The rain will then enter at the rear gap and fill up the pocket underneath the solar panel. In winter this can then freeze and damage the panel. The level of your parking area will also affect this too.

On the new panel I have now only completely sealed the front edge and sat the panel on 4mm adhesive beads that run across the width of the panel at regular intervals with a gap in the centre of each bead. The sides are open. The rear has a central drain slot.

This aids ventilation as well as easy drainage. The thicker beads allow for the different expansion rates of the panel and the roof substrate. You need to select an adhesive that has the elasticity and strength to do this.

Hi , so have you sealed any of the sides at all ?

 

[Dilbert]

Hi , so have you sealed any of the sides at all ?

No. All you can see at the sides is the finished off ends of the transverse beads of sealant.

We have not had any problems with noise, etc.

 

[andy greenwood]

No. All you can see at the sides is the finished off ends of the transverse beads of sealant.

We have not had any problems with noise, etc.

Thanks for that, I've not heard of anyone fit one like that before but it does seem very logical for ventilation and drainage.

 

[Dilbert]

I needed to try a new approach after 2 previous semi-flexible solar panels failed due to heat, expansion, trapped water/ice, etc.

Fingers crossed!

Here is a photo:

 

[andy greenwood]

I needed to try a new approach after 2 previous semi-flexible solar panels failed due to heat, expansion, trapped water/ice, etc.

Fingers crossed!

Here is a photo:

View attachment 132234

This might sound stupid but what about any crosswinds ? do you think there is a chance of the panel getting ripped off ?