Eaves height for photovoltaic system offer

The eaves only give the height a name. However, I think that for this purpose the "actual" eaves height is meant, because what informational value should the fictitious penetration height of the exterior wall through the roof covering have here?

Thanks, that helped me. I could still somehow understand the bearing point of the bottom edge of the rafters and the wall as a meaningful value, but the calculated virtual intersection of the wall with the outer shell of the roof has absolutely no significance. I find it odd to call that the eaves. Probably because without an overhang the gutter would have been attached exactly there. For the offer I will provide both values, then you can deal with them yourself to decide which value you need. The topic is thus settled.

Not in our development plan. It measures from the single-family house to the intersection between rafter and wall. The maximum ridge height then implicitly results from the permitted roof pitch (let's ignore the fact that a house with a larger base area also becomes taller ;) )

That may be so, that the maximum ridge height is defined as a calculation task with you. But only the result then determines the house height, and not already the "starting point" of the extrapolation at the fictitious eaves.

I could still somehow understand the support point of the lower edge of the rafter and the wall as a meaningful value, but the calculated virtual intersection of the wall with the outer shell of the roof has absolutely no significance. Calling that an eaves I find strange. Probably because without a roof overhang the gutter would have been attached exactly there.

Building law is not about sense, but about successfully fending off overly clever tricksters. Your assumption therefore does not lead to the reason, but only to the legally secure justification. The reason is to prevent said tricksters from being able to build their house higher by raising the gutter (through a roof overhang in the style of delicate claws) to the desired height (if it were the standard, and that is precisely why it is not). If you imagine the roof tiles as fingernails, the legally relevant gutter is simply hung fictitiously on the roof without an overhang, thereby removing the roof overhang as a lever for trickery.

Isn't it still strange to determine the building height at the exterior wall? Because even then, with the appropriate DN, you could build an asymptotically tall building (disregarding static limitations). Or is that just an additional criterion alongside the ridge height? Ah, just read - maximum DN (and presumably also the footprint?). Still a strange definition. Wouldn't it be simpler to use only the ridge height?

Isn't it still strange to base the building height on the exterior wall? [...] Or is that just an additional criterion alongside the ridge height?

The building height is not determined by most development plans based on the exterior wall either, but on the wall height (to which only the development plan from links its ridge height limitation). The building height corresponds to the ridge height - whether defined directly or indirectly (= via this strange calculation), excluding chimney. Eaves height, ridge height, and roof pitch maximum are a popular three-point safeguard against excessively tall buildings, and in my opinion quite reasonable (although I find it more appropriate to limit only two values, e.g. also from the triangle of floor area ratio - gross floor area ratio - number of storeys). On the other hand, I find it completely pointless to limit knee wall heights at all (since the measure of the position of the floor slab below the eaves height does not affect the building volume).

I think the motivation for the wall instead of ridge height is that [Pultdächer] are also allowed. There is no real ridge here, and even if you define the upper eaves that way, with 8 degrees the walls can become quite high. An 8-9m wall feels quite different from 6m plus roof.

I think the motivation for the wall height instead of ridge height is that shed roofs are also allowed.

The general motivation of development plans to use the term wall height gender-neutrally for the eaves height certainly lies in legally secure interpretation given the non-binary (there are not only "gable" or "flat" roofs) roof types. But that your development plan defines the ridge height as "wall height plus roof pitch times half the building depth" as a math problem is simply British eccentricity (they are crazy, those Romans).