Earlier quoted context omitted.
pvXchange, but they're €23 because you fucked up the math: https://www.solarserver.de/photovoltaik-preis-pv-modul-preis... €12 would be 44× cheaper (7000/6000/(12/450) ≈ 44). Maybe in a couple of years.
I assumed 7k installed, so roughly half for the panels. So how many do you need to buy to get that €23 price?
Typically panels account for about a third of the cost of a turnkey solar power system, but that's largely because of historical design features that are no longer necessary.