KFW 40 and QNG: Meaning of Photovoltaics and Storage

The Swabian housewife freezes the rest in portions and is taken care of. Of course, it’s not that easy with electricity, but the feed-in tariff in summer is not to be underestimated. Every little bit helps. And then it’s simply a calculation exercise of how much more expensive x kWp extra is. That then depends on the specific offer. It can also be worthwhile at 4% if you don’t pay exorbitant prices.

We want to build according to the KFW40 standard with QNG to receive the full subsidy. My questions: - Are photovoltaic + storage mandatory in this case? - Are there requirements regarding the performance of the panels or the capacity of the storage?

There are two answers to this. 1. Formal answer: No, photovoltaic and storage are not mandatory. Neither for 40 nor for QNQ. 2. Practical answer: Experience shows that as a builder, you usually need the advantages of renewable energy generation and high self-consumption in the house to obtain the sustainability certification. Additionally, it should be noted that this question does not arise in Hamburg/B/BW, as there is a photovoltaic obligation 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 as large. So you should carefully consider whether it really pays off. Especially with regard to heat pumps, air conditioning, electric cars.

I have now had a conversation with Mittelstädt and according to their statement, your house meets the QNG and KFW40 requirements even without photovoltaics. Since photovoltaics are now mandatory in Hamburg, but there are no specifications regarding the size, I assume that in this case a "Balkonkraftwerk" on the roof is the most cost-effective solution for us. Are there any opposing opinions?

This is just my opinion, but widely shared among experts (I am not one): roof full! Even in the North if the pitch is up to 30°. If, yes if the offer is not overpriced. Photovoltaics is the only investment that pays for itself, financially calculated. Roof full, no storage. At reasonable prices, payback after about 10 years. After that, the system does not explode but brings you a small additional income every month! Net ;-). Unless you cannot afford the investment, meaning: the bank does not give you the necessary 15 - 30K for it additionally