Solar panels on a steel roof

[TheCaller]

I'm just planning the fitting of a couple of solar panels. Most of the posts on here relate to fitting panels to a traditional motorhome with either an aluminium skinned roof or some variety of plastic.

I have a PVC on a Ducato Maxi van, so the roof is painted steel, with longitudinal ridges. The tops of the ridges & the bottoms of the valleys are flat & a couple of inches wide, but that suggests mounting brackets on the long edge of the panels running front to back on the roof, not crossways across the panel ends as a lot are on flat roofs.

Brackets on the ridges or in the valleys?

Just adhesive? No screws? Just clean the paintwork or key it?

Then the scary bit - where to drill the hole to bring the cables into the van? The largest flat area is where the main roof panel joins the over cab area to the front, & the side panel pre-prepared for attaching roof bars or an awning. That's just behind the 'B' pillar too, so a handy place to drop the wires down inside. I was thinking the wires could run behind the plastic cover where the seat belt is in the photo.

It's a Globecar Campscout, for anyone that knows the interior layout.

Any thoughts from those who have done this? Anything else I ought to be thinking about?

 

[f6c]

On the ridge

 

[Puddleduck]

My instinct would be to use the ridge as there is less chance of water pooling there.

 

[TheCaller]

On the ridge

... to get the air flow underneath?

 

[TheCaller]

My instinct would be to use the ridge as there is less chance of water pooling there.

True - and probably easier to clean (and, yes, of course I always clean the roof every time I wash it. ).

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[g8ysn]

get a reputable company to do it if vehicle is vat exempt don,t pay vat

 

[Enword]

Bonded mine on 4 x 50mm round alloy feet with Tiger seal in 2008 still there

 

[Enword]

Sorry steel roof (Sprinter)

 

[tonka]

I would mount on a ridge..
Entry, in through top of wardrobe ? You could run wires inside and maybe fit the controler / regulator in there. If needed you can then run cables out to the battery through the bottom of van..
One of the hardest jobs is just deciding the best way to run the cable...

 

[TheCaller]

Entry, in through top of wardrobe ?

Don't have one, or any other floor to ceiling enclosed space. One side of the van is top lockers only + bathroom. The only place where there is anything that runs concealed from top to bottom is on the other side where it goes behind the fridge, the oven & what would be a wardrobe except it's at floor level & only about 400mm deep. It's also in the wrong place for where the wires have to go next. That's why I was thinking of coming down the inside of the plastic 'B' pillar covering. There is also a false floor on that side to take the wires to the under dinette space for the controller, then forward again to the EBL99 under the passenger seat. I'm going to use a Votronic MPPT controller as it's the only one that will both take the voltage of two series wired panels & has an Electrobloc interface. Wiring to the EBL99 rather than to the battery(ies) means a) the EBL99 doesn't get confused by unexplained voltages at the batteries & b) also charges the starter battery without any extra wiring.

One of the hardest jobs is just deciding the best way to run the cable...

Too right!

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[Jimbohorlicks]

Rather than fixing directly to the van roof why not attach roof bars and put the panels on those -if you change your van at a later date you can then always take them with you

 

[TheCaller]

Don't have one, or any other floor to ceiling enclosed space.

Actually, I don't think that's quite true. I strongly suspect there is one or more channels between the inner & outer skin where the existing cables run. I'll have to go & watch that high speed video of them fitting out the interior of a Globecar in the factory again. I know that shows the channel where they route everything across the floor.

Probably have to dismantle half the van to get anything more through it, even if I can find it.

 

[TheCaller]

Rather than fixing directly to the van roof why not attach roof bars and put the panels on those -if you change your van at a later date you can then always take them with you

That's a good idea. Could be expensive though. I'll price up proper Fiat bars, probably faint, then look for some after-market ones! It might be cheaper to buy new panels!

 

[TheBig1]

good quality aluminium angle say 40mm x 40mm x 4mm could be bonded to the ridges on the roof and use the same to make support bars, bolted to that (use quality stainless hardware). keep it as simple as possible otherwise you're just making it harder than needed.

lay it all out and mark the points to bond at, then key the area with wet & dry. clean thoroughly and then use activator before applying the urethane glue (sikaflex). once its set, its never going to come off unless you take a knife or saw to it

have bonded several things including a huge satellite dome to steel panel van roofs. none have ever come loose

a bonus of setting the panels on a frame bolted to brackets is that you can unbolt them again for any servicing or to move to another vehicle

 

[Cal54]

Can't really help other than to advise that I had a panel fitted on the roof of my PVC last year by Dave Newell, trader and Funster. He will no doubt be able to offer advise re the roof ridges etc.

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[TheCaller]

I had a panel fitted on the roof of my PVC last year by Dave Newell

DN always on the short list for this type of work - just a shame that he's on the opposite side of the country. A good excuse for a mini-holiday, but it's all a question of finding the time! It seems a shame to just go straight there & back without making more of the trip.

 

[Cal54]

The caller: Dave fit mine at one of the Warner shows - if you are planning to visit Peterborough then you could book him there.

 

[Mousy]

Simon, @Wissel fitted panels to his roof, but I don't know where the thread is.

It may help you with the roof fixing but not the wire run as his was a conversion.

 

[Wissel]

I fitted mine onto 20mm square aluminium tubing along the short edges to give an air gap underneath.

I just used sikaflex to stick the tubing to the panels, then sikaflex again to bond to the ridges on my roof.

I then used a couple of these to bring the cables into my van:
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I was very dubious about just glueing the panels but assured by others that it's the best way. I was fitting another antenna to my roof a couple of weeks ago so had a good look at the solar panel fixing whilst up there. They are as well fixed now as they were 2 years ago.

 

[TheCaller]

Thanks for all the suggestions so far. Keep 'em coming.

I liked the idea of using roof bars utilising the Fiat mounting points. Nothing stuck permanently to the roof - easy to service or move to another van. But the positioning of the mounting points relative to the rooflights is not ideal. If I use bars alone (going across the van) I would need to make a frame to mount the panels on, so we would have bars (which already sit quite high from the roof), plus frame, plus panel. Not a good look & I'd rather not increase the overall height any more than essential.

If I use roof rails plus bars, I get the flexibility of where to position the bars & can mount the panels directly on the bars. It would look neater too. But it's an expensive option - looks like £400+ against some aluminium brackets & a tube of silkaflex. It also restricts the options if we ever decide to fit a wind out awning.

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[DBK]

Rather than fixing directly to the van roof why not attach roof bars and put the panels on those -if you change your van at a later date you can then always take them with you

Too easy for someone to steal the panels I think. I lost the keys for my Thule bars recently then looked on eBay and bought a new pair for £4.99 which arrived the next day. On the outside of every Thule roof back lock there is a number, clearly visible, so you just order keys to match this number and they will open the lock. Secure or what?

I also think you want your solar panels as low as possible so they are less likely to be knocked off by low branches.

I'm getting my camera out later and will take a picture showing how ours is mounted on our PVC.

 

[DBK]

This is how mine is fitted. There is a Z shaped extrusion held to the roof by two stainless steel self-tappers and what I assume is Sikaflex or some such stuff. The cable goes through a waterproof connection with only a very short cable run exposed - which I think is what you want to aim for so there is less to get caught on branches. Only problem with this installation is it is difficult to clean underneath the panel - hence the green stuff!

 

[Trikeman]

A lot of the vans like yours have a rack system fitted and then the solar panels fitted to that via J bolts. Benefits are that when you come to sell just whip off your panels and 'here we have a rack system' for the next owner.
Here is one that would be great for that. And a lot less than roof bars too.

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High enough to clean underneath too.

Hope it helps.

Regards,

Trikeman.

 

[TheCaller]

True - although I see he's selling it to mount solar panels directly on his roof!

 

[Jimbohorlicks]

I fitted mine onto 20mm square aluminium tubing along the short edges to give an air gap underneath.

I just used sikaflex to stick the tubing to the panels, then sikaflex again to bond to the ridges on my roof.

That,s a nice neat fix of the panels -the only issue i see is that it would be impossible to clean underneath the panels -unless they were screwed to the square ally tube side supports and could be lifted periodically

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[mitzimad]

i put mine down on a similar van with sika and a couple of self drilling screws i used the small cheap mounting brackets from ebay only about 3 inches long four on each panel and fitted to the tops of the ridges been on 4 years now no problems

 

[Peter A Forbes]

We have four 100W panels on our Mercedes 614D, the panel frames have inserts into their sides and we had aluminium angle feet along there screwed to the inserts.

The Mercedes roof is full of pressed-out bumps:

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So the fitting of the feet varied, with full-length feet on the outsides and multiple feet on the insides:

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The curvature of the top of the roof edge meant that we couldn't use a 90 degree angle there, but had some 10g NS4 Dural folded up to 95 degrees and that worked well.

We put double-sided foam between all joints, feet to panel and feet to roof, holes punched out using a drill shank:

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I know that many put their faith in Sikaflex and other adhesives for holding these panels on, but I want some mechanical security on mine, so M6 inserts and bolts into the roof and M5 inserts into the panel frames.

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All fasteners are A2 Stainless Steel socket button flange heads with a nylon sealing washer underneath.

Peter

 

[TheCaller]

Thanks for all the contributions.

The idea of mounting on a roof rack or bars has an obvious appeal, for ease of fitting, servicing & potential removal, but it's quite an expensive method & not terribly appealing aesthetically. Their ease of removal also makes them easier to nick, although I'm not sure that is a major consideration. There would be a minor effect on fuel consumption as well.

With panel prices dropping, the benefit of moving the panels to another van is getting less.

Wissel has the simplest method, but I'm thinking that brackets stuck to the roof, but bolted to the panels is probably the best compromise.

I still need to work out just where to bring the cables through the roof. Given that the hole in the roof will be covered by a sealed cable gland, what rustproofing treatment is needed to the edge of the newly drilled hole?

 

[TheCaller]

We have four 100W panels on our Mercedes 614D, the panel frames have inserts into their sides and we had aluminium angle feet along there screwed to the inserts.

Thank you Peter. Yours was posted while I was writing my last. I'll go back & study yours more closely.

 

[Peter A Forbes]

The panels are in two groups of two, each pair feeding their own MPPT controller.

The cables go into two sealed boxes on the roof and then through the box into the van via a gland.

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Pictures are of the trailer, but the same boxes are used on the Mercedes.

Peter

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