Rust on solar panel screwheads - coat or replace?

[Dylan T]

Hi all - I'm currently in the early stages of a van conversion and had a DIY question i was hoping some kind folks could help with. I've fitted some solar panels with some self-drilling/self-tapping screws that came with the kit which I've used to attach it to the roof (along with sikaflex). It feels super solid but after only a few days I've noticed the screw heads rusting. I really don't want to have to change them so I'm wondering in these instances if I either coat with hammerite or sikaflex (I've already covered the base of them in sikaflex for waterproofing, and it doesn't matter how things look up there) would that be sufficient to stop the rust if I do my best to remove what I can first? Hammerite does say you. can put it on rust and it prevents it but I want to make sure. The fixings did say they were fully galvanised and weather proof but lesson learned - always get your fixings from a place you trust!

Image attached.

Thanks

 

[opps]

you can just pop on some nut cover caps if you want.

https://www.orbitalfasteners.co.uk/search?term=nut cover caps

Orbital Fasteners will sell you as little as one but the min order for free delivery is £25 ex VAT. Great company, and if you live in the M25, next day delivery.

 

[Harry Bloomfield]

Normal, good quality caravan construction, uses stainless fixings all round. Could you replace them with a stainless steel version?

 

[Dylan T]

you can just pop on some nut cover caps if you want.

https://www.orbitalfasteners.co.uk/search?term=nut cover caps

Orbital Fasteners will sell you as little as one but the min order for free delivery is £25 ex VAT. Great company, and if you live in the M25, next day delivery.

Thanks that's a good idea but they have so much sikaflex on them they wouldn't fit - so once removed I may as well replace the screws

 

[Dylan T]

Normal, good quality caravan construction, uses stainless fixings all round. Could you replace them with a stainless steel version?

It would be a real pain - It's an option but I was hoping to avoid it

 

[opps]

Thanks that's a good idea but they have so much sikaflex on them they wouldn't fit - so once removed I may as well replace the screws

Fair enough. Coating them in Sikaflex should be fine. It won't prevent you from removing them in the future.

 

[Dylan T]

Fair enough. Coating them in Sikaflex should be fine. It won't prevent you from removing them in the future.

Thanks - you'd go that over the hammerite? (it's the white stuff that goes over rust that ive been using in the van as a primer when cutting holes and on the floor over rust)

 

[opps]

Sikaflex is a MS polymer.

If you were to apply regular oil based paints directly to a MS polymer, the paint would remain tacky for a very long time (possibly years). You can prime them with waterbased paints first though. Hammerite uses cellulose thinners as a solvent. I have no idea if it will be suitable even if you prime with waterbased paint first. In the past I have used cellulose thinners to remove water based paints, so I wouldn't want to use Hammerite over waterbased paints (that said, I have never tried).

From memory, Sikaflex EBT is suitable for exterior use without painting, not all MS polymers are though. Personally, I would just smear the Sikaflex on and leave it as it is.

 

[JohnD]

Normal, good quality caravan construction, uses stainless fixings all round. Could you replace them with a stainless steel version?

That's the best option.

If they are going into aluminium, use Nickel anti seize compound to avoid corrosion. Not copper grease.