ᐅ KfW 40 and QNG: The Role of Photovoltaics and Energy Storage
Created on: 23 Sep 2023 21:50
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Schnubbihh
Hello dear community,
We are currently planning a new build, and one of my biggest questions is about sizing the photovoltaic system on the roof.
We want to build according to the KFW40 standard with QNG certification to receive the full subsidy.
My questions:
- Are photovoltaic panels plus storage mandatory for this?
- Are there specific requirements regarding the power output of the panels or the capacity of the storage system?
I would like to get a better understanding of the minimum requirements that need to be met in this area and what might be economically reasonable beyond that. Based on my current research, I tend to expect that I would keep the photovoltaic system to a minimum (roughly covering the base load).
I am very grateful for your opinions!
We are currently planning a new build, and one of my biggest questions is about sizing the photovoltaic system on the roof.
We want to build according to the KFW40 standard with QNG certification to receive the full subsidy.
My questions:
- Are photovoltaic panels plus storage mandatory for this?
- Are there specific requirements regarding the power output of the panels or the capacity of the storage system?
I would like to get a better understanding of the minimum requirements that need to be met in this area and what might be economically reasonable beyond that. Based on my current research, I tend to expect that I would keep the photovoltaic system to a minimum (roughly covering the base load).
I am very grateful for your opinions!
W
WilderSueden24 Sep 2023 19:02The Swabian housewife freezes the leftovers in portions and is well supplied.
With electricity, of course, it’s not that simple, but the feed-in tariff in summer should not be underestimated. Every little bit helps. It then becomes a calculation of how much more expensive x kWp extra is. That depends on the specific offer. It can also be worthwhile at 4% if you don’t pay exorbitant prices.
With electricity, of course, it’s not that simple, but the feed-in tariff in summer should not be underestimated. Every little bit helps. It then becomes a calculation of how much more expensive x kWp extra is. That depends on the specific offer. It can also be worthwhile at 4% if you don’t pay exorbitant prices.
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KarstenausNRW24 Sep 2023 21:04Schnubbihh schrieb:
We want to build to the KfW 40 standard with QNG certification to qualify for full subsidies.
My questions:
- Are photovoltaic panels and battery storage mandatory for this?
- Are there requirements regarding the output of the panels or the capacity of the storage system?There are two answers to this.1. Formal answer: No, photovoltaic panels and battery storage are not strictly required. Neither for KfW 40 nor for QNG.
2. Practical answer: From experience, as a builder you usually need the advantages of renewable energy generation and high self-consumption in the house in order to obtain the sustainability certification.
Additionally, it should be noted that in Hamburg/B/BW this question does not apply, as there is a mandatory photovoltaic requirement for new buildings there anyway. A small “token” system (e.g., 4-5 kWp) is often 500-800€ per kWp more expensive than a system twice its size. So it is worth carefully considering whether it really pays off—especially when taking into account a heat pump, air conditioning, or an electric vehicle.
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Schnubbihh26 Sep 2023 19:11I just had a conversation with Mittelstädt, and according to them, your house meets the QNG and KfW 40 standards even without photovoltaic panels. Since photovoltaic systems are now mandatory in Hamburg, but there are no specific requirements regarding their size, I assume that in this case, a small-scale rooftop system ("balcony power plant") would be the most cost-effective solution for us. Are there any opposing opinions?
This is just my opinion, but it is widely shared among professionals (though I am not one): fill the entire roof! Even on north-facing roofs if the pitch is up to 30° (degrees). That is, if the offer is not overpriced. Photovoltaics are the only investment that, from a financial point of view, pays for itself. Fill the entire roof, no battery storage. At reasonable prices, the payback period is about 10 years. After that, the system doesn’t wear out but instead provides you with a small additional income every month—net income ;-). Unless you cannot afford the investment, meaning the bank does not approve the required 15,000 to 30,000 (15 to 30K) for it.
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