Construction costs are currently skyrocketing

Our Nelskamp are not treated and I can already say that after a few years they will no longer look as glossy gray as they do now. Apparently, you should not treat them at first because concrete becomes harder over time (?!) and the tiles essentially get better after 2-3 years. I was told that you can have them treated later, which costs about 4-5000€ for the complete 100sqm bungalow roof. Whoever can should choose engobed tiles, hardly more expensive and they last forever. However, our house builder wanted a hefty surcharge for our budget.

A question about concrete roof tiles. Are they treated in any way? We decided against them because the roofs covered with concrete roof tiles looked really bad after 5-10 years.

They are coated. In new development areas that were built 5-10 years ago, I cannot see that concrete tiles look bad.
And even if they do, as long as the roof is watertight, moss can comfortably grow on it.

For the concrete roof tiles, we pay an additional €400 for the entire roof and in return receive the slightly smoother "perla" coating, which also shines a bit more than the standard tiles. I found the additional cost completely reasonable.

which at the same time also shine a bit more than the standard stones.

(Probably not the case for you) but with something like that I would possibly always check if it is prohibited in the development plan (it is in some here). (Otherwise, I personally do not find shiny bricks so nice either, but that is a matter of taste).

Yesterday, our photovoltaic storage system was put into operation. The installer said that the gross price we paid for the system would now have to be paid at least net, so 20% more. Rails, aluminum systems, apparently don't exist at all, they all come from Russia. The manufacturer has cut 60% of the ordered storage units for this year. Offers are only available for implementation next year and with a price adjustment clause.

Yesterday our photovoltaic storage system was put into operation. The installer said that now we would have to pay at least the net price for the system that we previously paid as a gross price, so 20% more.
There are apparently no rails or aluminum systems at all; they all come from Russia. The manufacturer has cut 60% of the ordered storage units for this year. Offers are only available for installation next year and with price adjustment clauses.

That is just an excuse to rip people off; last week 11,000 euros for 8 kW plus rails, cables, etc., including an inverter from Huawei. Installation is done by ourselves; the acceptance is done by our company’s external electrician. Yes, he is allowed to do it.

But as long as people pay 30,000 euros for 10 kW because they are afraid, unfortunately it won’t get cheaper.
They charge 430 euros for 100 meters of cable. That is fraud.

Or 3,500 euros for installation plus another 500 euros for connection, and at the very bottom there is still a fee of 350 euros for registration.

By the way, in December I paid only 8,200 euros for 10 kW with K2 rails and a Kostal inverter.
Unfortunately, the battery is not deliverable, although I tried to dissuade my buddy from buying it.
And to invest the 6,000 euros in additional modules instead.

The system has been running since December. All installation done by ourselves.