ᐅ Credit of photovoltaic electricity toward primary energy demand

Hello,

can someone briefly explain how photovoltaic electricity affects the primary energy demand in KfW Efficiency Houses? Suppose the energy performance certificate shows a primary energy demand Q"p of 32 kWh/m²a (32 kWh/m² per year). How would, for example, a photovoltaic system with 1 kWp impact the primary energy demand of 32 kWh/m²a? Can this be estimated roughly, or does it have to be calculated precisely? Usable floor area is 253 m² (2,723 ft²).
Are additional data needed? Thank you.

According to §5 of the Energy Saving Ordinance 2014, photovoltaic systems are deductible from Q_p under the principles described there.

A corresponding calculation according to DIN standards (x/y, I don’t recall the exact numbers) must be carried out. This requires a considerable amount of additional data such as location, roof pitch, energy generation, self-consumption rate, and so on.

Therefore, no one can tell you here how this will affect your individual case.

I understand that no one here can give me an exact answer. I was just hoping to get at least a rough idea of the impact, for example, if a photovoltaic system produces about 1000 kWh annually. How much could the primary energy demand be reduced by?

world-e schrieb:
if the photovoltaic system, for example, produces an annual yield of 1000 kWh. How much can the primary energy demand be reduced?

Your question is charming.

But how is anyone supposed to answer that?
No one knows your estimated proportion of self-consumption, or whether you are using a storage system or not.

No one knows your heating system or ventilation. No one knows your auxiliary energy demand (which is also reduced depending on all the other factors).

Again: This has to be calculated very thoroughly and individually for your house, your system, and your specific conditions.

Anyone who tries to guess here would give very poor advice.

A small tip:
I tried to have it calculated afterward because my photovoltaic system was installed later.
It would have been pointless—there are effects, but nothing significant; it wouldn’t have changed any rating in retrospect. However, if it had been considered initially, it probably would have resulted in a small improvement for my house from KFW-70 to 55.
So: It is one component of the KFW calculation. But it depends on many parameters.
Definitely have it professionally calculated, as I said...

Okay, now I understand that my question cannot be answered the way I had hoped. Thank you very much for the explanations.