Solar reflective window film extremely hot when sun is out

[Michaelsf90]

I've recently used a product called coolkote on my lean to polycarbonate roof. One thing I've noticed is when the sun is out this product gets extremely hot. It isn't burning my hands but its like when your washing up and the sink water is hot but not too hot to not put your hands in. It feels incredibly warm tho. I guess the question I'm asking is has anyone ever used anything like this? Is heating the polycarbonate sheet up so much going to lead to problems? I must admit it's far more comfortable in there now. No sun glare. Not absolutely unbearably hot. I'm just concerned about any impact on the integrity of the roof

 

[RandomGrinch]

I'm guessing you applied the film to the interior of the glazing?
If so, the sun's UV content can shift wavelength to infrared, as it's reflected back through the depth of the glazing material; this can cause heat to build up within it.
Ideally the film would be applied to the exterior of the glazing.
Polycarbonate is about 95% transparent to IR, but that leaves 5% that can be absorbed by the glazing as heat.
So the polycarb will heat up, but not as much as if it were glass.
As the Coolkote specifically states it is suitable for polycarbonate glazing, and you have installed according to the manufacturers instructions, there shouldn't be anything to worry about.
However, if you are concerned, try and contact the supplier, and find out what a safe surface temperature should be.

 

[Michaelsf90]

Yer it's on the interior. It would be impossible fixing it to the exterior with it being polycarbonate. It's designed to be fitted internally with the heat reflection being on the adhesive side.

I've contacted them and they just state its designed for polycarbonate and the film gets hot because its reflecting the heat back. So my guess is the film is what's hot and not the polycarbonate itself. I felt the outside and the polycarbonate was cold to touch. Its twin or multiwall so only the inside layer will be hot if that's even hot and it's literally not just the film. But the glazing bars are plastic and aluminium and the rubber seals feel very warm. So it's going to add thermal stress to something. Just hope it holds up. It's made worse now by more extreme weather's. When it's hot it's hot and then when it's cold its cold. Its not exactly temperate anymore