Energy saving certificate, coverage share/solar system, which values?

Hello experts. Who can help me? In my energy savings certificate, a coverage ratio of the solar system for water heating of 62.5% was calculated. Since this value seemed very high to me, I had a solar simulation created by the manufacturer. This simulation resulted, due to the orientation of the system (west), in only 44% coverage. The question now is whether the real figures have to be used in the energy savings certificate or if some idealized laboratory values are allowed to be included.

Hello,

...The question now is whether the real figures have to be used in the energy saving certificate or if any idealized laboratory values may be included...

The question reveals that this is primarily about the "paper form."
What is the opinion of the certifier on this?
Energy Saving Ordinance or KFW certificates have nothing to do with reality, due to standardized boundary conditions.
Even the provider's simulation is probably too optimistic ;-) Real user behavior, storage state of charge, differentiated irradiation levels (daily cycle) are the causes here.
Simply install a heat meter and compare the results with the actual "yield"! At the same time, have the provider guarantee a "yield" or coverage rate in writing.
In the latter case, it is quickly noticeable that hardly any contractual solution will be found here ;-)

Best regards

It is clear to me that the theoretical values do not necessarily allow conclusions about the real conditions. But even in theory, the whole thing must be calculated with the correct data. In the case of solar influence on the building, it is also considered whether a window is on the south or north side of the house. It cannot be that this consideration is not made at all for the solar system. Imagine the system is mounted on the north side of the building due to structural conditions. The yield would be zero and the builder would be left empty-handed??? Definitely, the assumed 62.5% was based on a south orientation of the system, but it is planned with a west orientation. There must be corresponding regulations to take these facts into account in the energy saving verification.

... Imagine the system is mounted on the north side of the building due to structural requirements. The yield would be almost ZERO and the client would be left empty-handed???

They end up empty-handed more often than they would like.

... Definitely, the assumed 62.5% was based on a south-facing system, but it is planned with a west orientation. There must be corresponding regulations to take these facts into account in the energy saving verification.

These regulations already exist => Energy Saving Ordinance/KfW verification! These always take precedence over detailed planning, i.e., if a roof orientation "west" is defined there, you cannot later arbitrarily change it to "east."

They end up empty-handed more often than they'd like. The regulations already exist => Energy Saving Ordinance/KfW certificate! These always take precedence over the detailed planning, i.e., if a roof orientation "west" is defined there, you can't later just arbitrarily choose "east."

v.g.

The crazy thing about this is that the orientation of the solar system is nowhere described in the Energy Saving Ordinance/KfW certificate. In the system assessment, only the coverage ratio is given, but where this number comes from is not explained. The deeper you delve into these matters, the more places you find where manipulation is possible without it being immediately noticeable. That the legislator allows something like this is beyond me. I certainly feel deceived! A value is given that the manufacturer of the systems hardly reaches in the simulation calculations, so the whole calculation should actually be wrong!

The crazy thing about it is that the orientation of the solar system is nowhere described in the Energy Saving Ordinance/KfW verification. In the system analysis only the coverage share is given, where this number comes from is not described.

That is not entirely correct. The orientation is indeed considered, but not the specific boundary conditions, which can significantly influence the profitability in individual cases ;-)

...The deeper you delve into these things, the more points you find where manipulation is possible without it being immediately noticed. It is beyond my understanding that the legislator allows such a thing. I certainly feel deceived!

The legislator has to fulfill overarching objectives, not to ensure the individual economic well-being of each builder!

...There is a value given which the manufacturer of the systems by far does not achieve in the simulation calculations, and thus the whole calculation should actually be wrong!

Simulation calculations usually only satisfy the proof on paper! They usually have little to do with real practice, the actual profitability for the individual builder.
Many, however, are guided by the misconception that gifts (e.g. KfW subsidies) are being handed out ;-)