To return to the idea of the rather elongated house oriented towards the back, we might possibly install a photovoltaic system on the roof either immediately or later. It probably wouldn't be as efficient since the roof would have an east-west orientation, is it still worth it? Or would it be better to put it on the garage roof instead?
We were told that east-west is even better. On the one hand, you can cover both sides (which is possible with north as well, but not as efficient). On the other hand, the electricity is then produced more when people are usually at home, namely in the morning and evening.
.. so with our triple glazing windows, you can only look inside when it is dark outside and the house is lit; under normal daylight conditions, you have to stand right in front of the window to be able to look inside.
we might possibly install a photovoltaic system on the roof now or later, which would then probably no longer be as efficient
On the one hand, that is another field altogether, but on the other hand, the main thing should remain the main thing, i.e., one should not optimize the house according to the photovoltaic system. After all, we are not located so tropically here that a few modules on the roof would already make us self-sufficient.
we might possibly install a photovoltaic system on the roof directly or later, but it probably wouldn't be as efficient since the roof would have an east-west orientation; is it still worth it? Or would it be better to put it on the garage roof?
.....all of that should, in my opinion, be absolutely secondary. If you include this in the floor plan design, you might have to make compromises, and especially the floor plan should have as few compromises as possible. I think you can always manage to get some photovoltaic system going – house usability absolutely takes priority!