Renewal of heating system in old building, which system?

Of the 8 offers so far from four different companies in and around Munich, the price was always between 1400 - 1500 EUR per kWp. It looks to me like extreme price fixing in this region. However, I have to add that I need a meter cabinet conversion to the "Einzählervariante".

Looks to me like price fixing in this region.

Then just google clen solar... At least for me, one meter for self-consumption is included.

Back again to the topic of heat pump:

I once used a seasonal performance factor calculator myself:

This time with a planned 40 degrees flow temperature startup, since we generally have underfloor heating in the house, only not on the 1st floor. However, there is still a tiled stove there, which we could use additionally during very cold winters. Or simply increase the flow temperature of the heat pump for those days. But the winters in our southern region have always been very mild recently.



My standard overall heating load calculation:

I have entered the values independently. For windows, we are generally actually below a U-value of 1.0, but our conservatory still has double-glazed windows. The top floor ceiling is currently not insulated. The lowest floor ceiling has built-in underfloor heating and insulation on the concrete. The exterior wall has 10 cm of thermal insulation on solid brick. The basement can be partially heated with underfloor heating.



The company calculated as follows:

Heated area 200 sqm
Standard heating load 21.86 W / m2
Total heat generator capacity 11 kW
Building heating load 11 kW
Coverage ratio of the heat pump 100%
Output share of the heat pump 78.36%

Seasonal performance factor heating 3.9 without auxiliary heater and 3.9 with auxiliary heater
Seasonal performance factor domestic hot water 4.0 without auxiliary heater and 4.0 with auxiliary heater
Seasonal performance factor according to VDI 4650 -> 3.9

Flow temperature 55 degrees
Domestic hot water storage 50 degrees

The company states their COP for the air-water heat pump as follows:

It is supposed to be a larger heat pump for us with over 8 kW capacity, which means two outdoor units stacked vertically.

Performance factor COP A-7/ W35 -> 2.71
Performance factor COP A2/ W35 -> 4.28
Performance factor COP A7/ W35 -> 5.61

Note:
We are possibly planning to install a photovoltaic system with 8.16 kWp and a 9.6 kWh storage on our south-facing roof.
Calculated grid feed-in approx. 9262 kWh per year.
Currently, our own electricity demand is about 3000 kWh, probably later about 4500 kWh.

Electricity consumption of the heat pump:
For the electricity consumption, one would now calculate heating load divided by the seasonal performance factor multiplied by 2000 (heating hours) resulting in the following electricity consumption:
11 kW / seasonal performance factor 4.5 x 2000 = 4888 kWh, i.e. with a heat pump meter with heat pump tariff kWh at 20 ct approx. 1000 EUR / year (84 EUR / month) electricity costs for the air-water heat pump.

I also visited a reference customer who has a KFW55 house (but with tubular radiators?). He runs the somewhat smaller system of the provider year-round for 130 m2 at about 55 flow temperature and had about 4000 kWh electricity consumption per year.
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Questions:

1.) Do you think the calculation is realistic? With a seasonal performance factor of 4.5 for an air-water heat pump at only 40 flow temperature?
2.) Would you now recommend the heat pump to me? With the updated calculation?
3.) If it is uneconomical regarding electricity costs, would it be sensible and profitable again with the above-mentioned combination of a photovoltaic system?
4.) Is it actually allowed to ask here about experiences with air-water heat pump models as long as no prices etc. or advertising is made?

Thanks for your feedback.

Could I still receive feedback on my additional calculations in the above post? Thank you. Best regards

I was also at a reference customer, who however has a KFW55 house (but with tubular radiators?). He runs the somewhat smaller system from the provider for 130m2 all year round at about 55 flow temperature and had about 4000 kWh electricity consumption per year.

Catastrophic!!!

1.) Do you think the calculation is realistic? with an annual performance factor of 4.5 for an air-to-water heat pump at only 40 flow temperature?

Could be a bit too high. Would you manage with 40 degrees flow temperature?

3.) If it is uneconomical regarding electricity costs, would it become meaningful and profitable again with the above-mentioned combination of a photovoltaic system?

Once again – photovoltaics have nothing to do with heat pumps and do not suddenly make an uneconomical heat pump profitable. You have to finally understand that. Consider both systems separately!

4.) Is it actually allowed here to ask about experiences with air-to-water heat pump models, as long as no prices etc. or advertising is done?

Yes

Hi, yes, I would definitely try to manage initially with a flow temperature of 40 degrees, since in the basement and ground floor I only need a flow temperature of 30 - 35 degrees anyway because of the underfloor heating. To what extent the new low-temperature radiators on the first floor will then have to provide enough heat, we will have to see. In general, we heat from bottom to top, heating the first floor a little as well. This is also based on the experience of the former resident of the first floor. He said he almost never had to heat. In the southern area, we have large window surfaces (conservatory and large windows).

What do you say about the statement from the heating company that with the heat pump from Vaillant VWL 125/6 A and the COP calculation no electric heater will be needed.

The heat pump has a max. heating capacity of 8.63 kW. We have about 200 square meters of living area to heat. Heating load of the building about 11 kW. The annual performance factor of the air-to-water heat pump is said to be 3.9.

Heating capacity / Electric power / COP at A-7/W35					11.8/4.92/2.4 kW
Heating capacity / Electric power / COP at A2/W35					5.9/1.28/4.6 kW
Heating capacity / Electric power / COP at A7/W35					8.5/1.57/5.4 kW
Heating capacity / Electric power / COP at A10/W35					8.8/1.54/5.7 kW