The cost of installation, wiring and transformers is more than the cost of panels.

They likely factor all those costs into the panel costs. But would labor and parts overhead represent 9/10ths of €8500, for example? Looks like they install 3 boxes in the basement plus panels for around €7500.

After the 30 years of “borrowing” the panels, who pays for their removal and recycling?

I assume that’s the homeowner because the supplier simply makes it all the homeowner’s property after 30 years… likely so they don’t have to deal with it.