ᐅ Energy Performance Certificate, Coverage Ratio/Solar System: What Values Should Be Used?

Hello experts.
Who can help me? In my energy performance certificate, a coverage rate of 62.5% for the solar system’s contribution to hot water production was used. Since this value seemed very high to me, I had a solar simulation created through the manufacturer. This simulation showed only a coverage rate of 44% due to the system’s orientation (west).
The question now is whether the actual figures must be used in the energy performance certificate or if any idealized laboratory values are allowed to be included.

Hello,

Bauprojekt2010 schrieb:
...The question now is whether the actual figures must be used in the energy performance certificate or if any idealized laboratory values are allowed to be included...

This question suggests that the focus is primarily on the “paperwork.”
What is the opinion of the certifier regarding this?
Energy saving regulations or KFW certificates have nothing to do with reality, as they are based on standardized conditions.
Even the provider’s simulation is probably too optimistic ;-) Real user behavior, storage charge levels, and varying solar radiation (daily cycle) are the main factors.
Simply install a heat meter and compare the result with the actual “yield”! At the same time, obtain a written guarantee from the provider regarding “output” or coverage rate.
However, it quickly becomes apparent that such a contractual agreement is unlikely to be reached ;-)

Best regards

I understand that theoretical values do not necessarily reflect real conditions. However, even in theory, the calculations must be based on accurate data. When considering the solar impact on a building, it is standard to take into account whether a window is on the south or north side of the house. It cannot be that this consideration is completely ignored when evaluating a solar panel system. Imagine if, due to structural constraints, the system is installed on the north side of the building. The yield would be virtually zero, and the homeowner would be at a complete loss.

The assumed 62.5% performance was definitely based on the system being south-facing, but the plan is actually for a west-facing orientation. There must be specific regulations requiring these facts to be included in the energy performance certificate / building energy report.

Bauprojekt2010 schrieb:
... Imagine the system is installed on the north side of the building due to structural conditions. The yield would be virtually ZERO, and the owner would be at a total loss???

They face losses more often than they would like.

Bauprojekt2010 schrieb:
... The assumed 62.5% was definitely based on a south-facing system, but it is actually planned with a west orientation. There must be corresponding regulations requiring these facts to be taken into account in the energy performance certificate / energy savings calculation.

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

€uro schrieb:
They are often left empty-handed more often than they would like.
The regulations already exist => Energy Saving Ordinance / KfW certification! These always take precedence over detailed planning, i.e., if the roof orientation is defined as "west" there, you cannot later arbitrarily change it to "east."

Regards.

The strange thing about this is that the orientation of the solar system is not described anywhere in the Energy Saving Ordinance / KfW certification. In the system assessment, only the coverage ratio is given, but where this number comes from is not explained.
The deeper you look into these matters, the more points you find where manipulation is possible without being immediately noticed. I do not understand why the legislator allows this. I certainly feel misled! A value is given that the system manufacturer cannot remotely achieve in simulation calculations, so the entire calculation should actually be incorrect!

Bauprojekt2010 schrieb:
The crazy thing is that the orientation of the solar system is nowhere described in the energy saving ordinance/building energy certificate or KfW verification. In the system analysis, only the coverage percentage is given, but where this number comes from is not explained.

That is not entirely correct. The orientation is indeed taken into account, but not the specific conditions that can significantly affect the economic viability in each individual case ;-)

Bauprojekt2010 schrieb:
...The deeper you get into these things, the more places you find where data can be manipulated without it being immediately obvious. I don’t understand why the legislator allows this. I definitely feel deceived!

The legislator has to fulfill overarching objectives, not ensure the individual economic benefit of each homeowner!

Bauprojekt2010 schrieb:
...A value is given there that the system manufacturer does not come close to achieving in their simulation calculations, so the whole calculation should actually be wrong!

Simulation calculations usually only serve as a proof on paper! They often have little to do with the real-world performance or actual economic benefit for the individual homeowner. Many, however, are misguided by the misconception that grants (e.g., KfW subsidies) are simply handed out as gifts ;-)

Best regards