Fixing a Solar Panel to Roof

[paulo999]

I've got myself a big panel. It's 100w, and I went for semi flexible so I can mount in on my (slightly curved) high top, without resorting to roof bars and all that. The panel has 6 bolt holes.

So, best way to mount?

My current thinking is, not to bond it directly. It's the sort of thing that would be a massive pain to put right if I got it wrong, which I probably would. Instead:

- Rubber strips glued to roof, to act as cushion.
- Place panel in position.
- Mark places to drill, through the bolt holes
- Drill holes through high top (fibreglass). (point of no return!)
- Bolt panel down, possibly with gromits to even up with the rubber strips.
- Maybe seal bolts edges with bathroom sealant?
- Inside, plastic/rubber caps for protruding bolts, to reduce any head injury stuff!

Obviously I'll also need to drill for the wires, and run them round the headlining in some fashion. Will try to fit the regulator in the battery box if I can.

Anyone got any thoughts?

[Oldiebut goodie]

There is no need for protruding bolts inside - put them in from inside!!!!
Suggest you use a polyurethane adhesive/sealant rather than silicone/bathroom sealant.
Usually you need to have an air gap behind the panel to prevent overheating so don't forget to factor that into your calculations/purchasing list. (I don't know how relevant that is to flexible panels though)
Some flimsy manufacturers mount their panels purely by bonding to the roof with the polyurethane sealant/adhesive.

Afterthought:
don't mount the controller in the battery box - you can't see it there!!!

[paulo999]

Yeah, after pondering bolts, I realised the other way round would best.

Thanks for the thoughts on sealant.

The rubber strips will create an air gap. Also, the pv cells are bonded to a metal sheet (steel I assume), so that should be a good heat sink.

[Oldiebut goodie]

It may be a heat sink but there still needs to be adequate airflow to enable it to work - OK when driving with a small gap but not so when stationary.

[paulo999]

It may be a heat sink but there still needs to be adequate airflow to enable it to work - OK when driving with a small gap but not so when stationary.

Well, in theory these flexible panels are for bonding on, but I'll take heed.

Probably won't get round to mounting it before I head for my two week stint at Glastonbury. So I'll try it on the ground there initially, and then mount it once I'm happy. I'll be taking all the bits with me, battery drill and all, and am in crew camping with time on my hands before things get busy.

[AngeloEvs]

The on ly problem I found with mounting on a roof was keeping the Solar panels clean. They get very dirty, bird droppings on one of the cells, leaves, dust, etc, reduces the efficiency. Just make sure you can get to it easily to give it a wipe over every so often.

I fitted two rigid 80W panels onto my Hymer and used 'Silkaflex' to bond aluminium strips to the roof onto which the panels were then bolted. I tried to remove the strips and keep my Solar panels -those strips would not budge so sold the panels with the van.....

I have seen those flexi ones used on marine craft, the ones I saw can be rolled up like a carpet and basically laid out on any surface or even hung up like washing. I would check about the need for an airgap with the manufacturer. I had to have a 10mm airgap on my conventional rigid panels and they got extremely hot in good weather but they are covered in glass which traps the heat. The flexi type isn't covered with glass!

[paulo999]

The on ly problem I found with mounting on a roof was keeping the Solar panels clean. They get very dirty, bird droppings on one of the cells, leaves, dust, etc, reduces the efficiency. Just make sure you can get to it easily to give it a wipe over every so often.

I fitted two rigid 80W panels onto my Hymer and used 'Silkaflex' to bond aluminium strips to the roof onto which the panels were then bolted. I tried to remove the strips and keep my Solar panels -those strips would not budge so sold the panels with the van.....

I have seen those flexi ones used on marine craft, the ones I saw can be rolled up like a carpet and basically laid out on any surface or even hung up like washing. I would check about the need for an airgap with the manufacturer. I had to have a 10mm airgap on my conventional rigid panels and they got extremely hot in good weather but they are covered in glass which traps the heat. The flexi type isn't covered with glass!

Thanks for input Angelo

Once mounted, it is certainly going to be awkward to clean - something I'll just have to put up with I guess. There's only a few trips a year where it'll be important for it to working at full rate, so hopefully it won't be too annoying.

Being a chinese import, I'm not holding out much hope for manufacturer's spec for airgap. I'm hoping it's been designed like the fully flexible ones, which don't need any air gap at all. Nonetheless I'll be raising it slightly, and it can be raised more still if need be.

One thing I hadn't bargained for was the challenges of drilling fibre glass. I've done alot of reading and everyone seems to have different suggestions, which is worrying. The 'right' drill bits, that don't 'pull' on the GRP, seem to rare as rocking horse poo, so I've compromised slightly and bulk bought bits for pilot holes and main holes. Apparently GRP can blunt a bit in a single use.

[Oldiebut goodie]

Don't worry about blunting drills - you are only going through a thin layer of glass - my boat is 5/8 of an inch thick glassfibre and doesn't blunt the drill. You are only drilling a few holes after all not doing a production run.

[paulo999]

Don't worry about blunting drills - you are only going through a thin layer of glass - my boat is 5/8 of an inch thick glassfibre and doesn't blunt the drill. You are only drilling a few holes after all not doing a production run.

Cheers. As it happens Screwfix only seem to do things in packs sizes of "far more than you need". So I won't be short on two particular sizes of drill bit for the next five years.

[jamesc76]

I glued mine on (well the brackets) with high grab sikaflex the only hole was for the power cable to enter my van, been on about 3 years now and not budged once!