Buy a house with an Eternit corrugated roof and install solar panels

Aside from the fact that what you are planning is completely forbidden... If a neighbor rats you out, you can dismantle the whole thing again. Why do you absolutely want to install a photovoltaic system on a minimum 50-year-old Eternit roof? The panels won’t get any better from people trampling on them. That combined with the lack of an underlay membrane... The risk would be too great for me. If you lack the money for the roof renovation, then skip the solar thermal system, the battery storage, fill the entire roof with photovoltaic panels, and decide either for pellets or for firewood, then there will even be something left over.

Apart from the fact that what you intend to do is completely illegal...

That is exactly my main question. Why is the whole thing illegal? Please explain what you are referring to.

According to GefStoffV Annex II, what you intend to do is fundamentally prohibited.

I hope someone has already had experience with this.

The records are now already 50+? years old and are supposed to last another 30 years. That will not work. If they still look fresh, they might actually be younger?