Window sun protection film outside

Hello,
I think this should be the right subforum...

Has anyone had experience with sun protection films that are self-adhesive and applied from the outside on the window panes?
They come in various versions.

We are looking for something like that for the windows in the children's room and bedroom, because it is already so stuffy and warm in the evenings due to the daytime sun that it is unbearable. Well, at the moment you can still ventilate and then it's somewhat okay (the heat that the furniture, flooring, etc. release then naturally warms everything up a bit again) but in the summer it will be really awful.

Roller shutters are currently too expensive for us; we don't have the budget for them right now... The blinds we have inside do prevent the sun from hitting, for example, the floor and heating it up, but between the blind and the glass a lot of heat builds up that then stays in the room... the controlled residential ventilation, of course, can’t compensate for that either, since it’s not an air conditioner after all.

Hello,
in general, I can say that such a film – with good quality – already blocks a considerable amount of heat. We have such a film at work on a relatively large window of a small corridor. It was always unbearably hot before the film was applied. The film brought a noticeable improvement.

Unfortunately, I cannot give you a concrete recommendation (manufacturer, model).

Hello, it's been a while, but always relevant!

So, sun protection films provide the most benefit when applied from the outside onto the glass panes. I can only speak from experience with the films we use ourselves. These are high-quality films from the Llumar brand. The films are available in different versions. We apply the films exclusively from the outside onto the glass panes.

Privately, I can report on the benefits of the sun protection films in relatively small children's rooms in Frankfurt, whose windows face south.
Before the windows were foiled, the children could not do their homework in their rooms during the summer. After the foiling, it was no longer a problem. The shutters can stay up, and the sun no longer causes glare.
The positive side effect is also glare protection.