Gable window, what kind of sun protection and how to darken?

Hello everyone,

now that we are slowly finishing our house, we are still missing a solution for our gable windows (see photo). The problem is that although we have roller shutters on the rectangular window below, the triangular gable windows above have nothing. Since this is on the south side, it will be nice and bright, but also very hot in summer and in addition, it should be possible to darken it in the evening (such a window is also in the children's room). I have now received an offer from a local company. A honeycomb blind, custom-made, but due to the size the warranty is excluded for just under 700 euros (including installation though) sounds like a lot at first glance. My question therefore is: are there any alternatives or does anyone have an idea what options are available here? Many thanks to you already! Hubi

One could simply stretch a canvas under the window up to the edge at the ceiling (as a spring roller blind).

How is the roof overhang,
for us 0.5m is enough to shade the window from May to August

One could simply stretch a canvas under the window up to the edge at the ceiling

This way no light comes in anymore, but the sun then warms the canvas. I have tried different solutions. Vertical blinds as curtains, quite expensive. Later then covered with films, cheap but also little success. Final solution external roller shutter. Extremely expensive.

I tried different solutions. Vertical blinds as curtains, quite expensive. Later then covered with films, cheap but also little success. Final solution outdoor roller blind. Extremely expensive.

What does extremely expensive mean? What was roughly the price range? I'm also unsure about the offered honeycomb blinds. In the end, you pay a lot of money and the success is moderate. But what irritates me the most is the exclusion of warranty. That actually shouldn't be acceptable. thanks for the tip with the spring roller blind. I'll think about it again.