ᐅ Electricity Costs for a KfW QNG 40 House

Hello,
I would like to ask if anyone has experience with a QNG 40 house featuring a 4 kWp photovoltaic system, a 5 kW battery storage, and a heat pump? My question is how much additional electricity needs to be purchased. It is a household of four people. Or what your annual electricity bill is? The house is a KfW 40 QNG or something similar.
The home seller says we would have to pay about 100 euros (around 110 USD) extra per month for electricity. That seems a bit low to me, especially in winter.
We use electricity for household consumption, hot water, and heating for four people, and possibly an electric car as well.
Thank you.

Without an electric car, I believe 100€ is rather too high than too low. KfW 40 or 55 standard doesn’t really make much difference here. The user’s behavior has a greater impact than the KfW level.

For 100€, you can actually get about 5,000 kWh for a year. Plus income from the photovoltaic system.

P.S. What on earth made you install such a small system on the roof? 4 kWp makes no sense – the roof should be fully utilized.

P.S. I have an old building on its way to KfW 40/55 standard with a 10 kWp system without storage. Also (partly) up to 5 people living there. But with home office and an electric car, the additional consumption is between 4,000-4,500 kWh, and I currently pay 156€ per month. This will decrease further once the insulation is completed. So, electricity cost without a car is about 70€ plus photovoltaic income.

Hello Karsten,
Thank you very much for your response.
I believe the KfW level only affects the heating consumption. Everything else (household electricity, hot water, electric car) is independent of the KfW level. We currently live in a 10-year-old apartment with an energy efficiency rating of B and pay around 200 euros annually for heating costs.

We have now received an offer for a semi-detached house with KfW 40 QNG certification. The offer includes only a 4 kWp + 5 kWh battery photovoltaic system. That seems a bit small to me, so I wanted to ask if anyone has experience with such a house or a similar setup.

My conditions:

- Semi-detached house KfW 40 QNG
- Household size: 4 people
- Electric car
- Photovoltaic system with 4 kWp and 5 kWh storage
- Heat pump for hot water and heating

Current consumption in the apartment:
- Electricity costs without electric car: about 3,000 kWh per year
- Heating and hot water via district heating: about 800 euros per year
- Cold water: about 400 euros

In the KfW 40 semi-detached house, we will get electricity from either the photovoltaic system or the grid.
My question is, what would be the approximate monthly electricity cost?

Thanks in advance.

P.S. One consideration is to remove the 4 kWp photovoltaic system and install a larger external system. However, the seller said that 4 kWp would be sufficient, and if we install a different photovoltaic system, it also has to be KfW 40 QNG certified.

What area are we talking about here? Depending on the specific design, your energy consultant might estimate somewhere between 10-15 kWh of electricity per square meter of usable building area (about 30% larger than the living area). This roughly amounts to 1500-2000 kWh of heating electricity per year. Even including hot water, that would be well under a hundred per month.

I can’t say anything about the QNG stuff.

WilderSueden schrieb:

What is the area we are talking about? Depending on the specific design, the energy consultant might estimate something between 10-15 kWh of electricity per square meter of usable building area (about 30% larger than the living area). This roughly results in a range of 1500-2000 kWh of heating electricity per year. That would be significantly less than one hundred per month, even including hot water.

I can’t say anything about the QNG stuff.

Then it is about 120m2 (about 1290 sq ft), which is the size of the semi-detached house.

We had heating costs of about €50 per month in our old house. KfW55 standard, approximately 150m² (1,615 sq ft) living space according to living space calculation, and a 4.5 kWp photovoltaic system without storage.