I would request in writing that the justification for these additional costs be provided with evidence of the relevant fee schedule. The mentioned items can hardly be included in the production costs.
Thank you all for the helpful feedback in such a short time. Since I cannot send personal messages yet, here is a reply to the post by Schorsch_baut: Yes, according to the notice, outdoor facilities and photovoltaics are assigned to the construction costs. Why do you think this should not be the case, or is there a legally substantiated opinion on this?
Because the most common legal definition, e.g. in tax law, is that manufacturing costs include expenses that are necessary to be able to construct the building and have actually served the construction of the building. In the case of photovoltaics, this item may still be understandable, but for exterior facilities that do not serve as excavation pit protection or as a construction road?