Construction costs are currently skyrocketing

I only just now see that I misread your question a bit. So we have no time limit for construction. That would also be a criterion against purchasing the plot for us.

We had an outdoor Schuko socket installed, fed with 5x2.5 mm2. In the box it is three-phase protected with its own RCD. Initially, only one phase of the Schuko was used; it all cost around 150 euros. Meanwhile, we can easily connect a wall box with 11 kW to it (22 kW would require a thicker cross-section).

For photovoltaics: the electrician was commissioned to install an empty conduit, M32, which he laid with some overhang from the distribution board to under the roof covering. We also commissioned the roofer to install the empty conduit through the roof covering in a second step and to seal it at the top with a sealed coupling. The total was also around 150 euros.

If you later need more than one string (one per roof side or roughly every 50 m2), take a thicker empty conduit or even two. And make sure the electrician does not make the bending radii too tight.

I'm an amateur here. They will probably just answer "a conduit will be laid, etc."

So really, even if it's expensive -> have conduits installed?

Here, 150 is now asked for dry RM beech.
It's only about the ambiance now, you probably hardly save anything.