Roof window blind solar or electric

But the developer categorically refuses to install pipes through the roof membrane. He even rejects empty conduits anywhere through the outer layer.

We are only allowed to make changes after the complete handover of the house. When the house is completely finished.

But after the complete handover, isn't it much too late to install the sleeve or am I thinking incorrectly?

Oh dear, that doesn't sound good but it's only a guess. My concern is that the builder cannot properly connect the roof window to the airtight layer (moisture membrane). Penetrations through the roof or through the airtight layer or membrane are common, e.g. for chimneys, ventilation, cables or solar lines, etc. There is always a collar or the correct adhesive tape, sealing system/sealing solution for this. How does he do it with your other penetrations through the roof?

Conduits are also dangerous, but not because of sealing, rather because temperature differences, e.g. from the roof to the basement, can create a kind of draft with condensation formation.

I fear that otherwise no cables will be laid through the roof.

The roof window is standard without a shutter and only available as a special service with solar (1600€ net surcharge).

If cables are needed from the roof to the basement, they can be routed through the technical shaft.
As a photovoltaic preparation, we have an empty conduit M40 from the roof to the technical room (200€ net) with a pull wire.

A cable for the roof window shutter was not planned by the builder.

Only the electrician suggested putting it in the outlet next to the roof window where he can lay the cable. Including a switch on the wall for 100€.
We just need to commission someone who can get the cable through the roof membrane to the shutter.