Floor plan of a new single-family house, 1.5 stories, 148 m²

Building 2-story without dormers and skylights with a gable roof and 22° pitch. If both sides are covered with photovoltaics (which makes sense at 22°), the orientation and basic shape practically no longer matter. Overall, the yield remains almost identical.

Ok thanks, then I will completely disregard that for now and sharpen the pencil.

I have a quick question. Which program/tool did you use to draw your floor plans?

Greetings, sorry I was very busy traveling. The floor plans were drawn by the house consultant, unfortunately I don't know with what, I use Sweethome3D, it is free and relatively easy to use, but it doesn't look very pretty. See the result below.

So I left the house size from the provider as it is and rotated it and moved the entrance to the gable side and changed the stairs, it is not perfectly drawn yet and the windows are placed somewhat randomly for now, but I wanted to ask if the general layout is okay like this. We like it very much but we welcome improvements. I might move things upstairs a bit to make room for the 2nd children's room and take away some space from the very large room.

Have you ever considered a half-turned stair landing? It would fit much better in this niche on the ground floor. With the current version, the starting point is poorly positioned around the corner... Another advantage would be that there is more space for a straight hallway upstairs. Because this distorted hexagon that currently results is not nice... Or, if the staircase absolutely has to stay like that, you could move the guest WC down on the plan and place the wardrobe next to the stairs or a narrow, long guest bathroom down to the bottom left of the plan with the entrance facing the stairs and use the side wall to the hallway for a nice long wardrobe cabinet. But then the problem of the hexagon upstairs would remain...

have you ever thought about a quarter-turn landing staircase?

How is one supposed to imagine something like that?