New build bungalow - air-water heat pump, photovoltaic and solar thermal?

Hello,

I have a few questions regarding our planning of a new build. We are still quite inexperienced when it comes to all the topics of house construction, but the forum has already helped us a lot.

A short background: we were on Saturday in a show bungalow of Town & Country. We have not yet looked at other show houses. Our wish is a bungalow with about 130m² of living space. The show house had solar thermal energy with an air-to-water heat pump installed including storage from Rotex. The house was completely equipped with underfloor heating.

We already liked the house very much. However, I have some questions regarding the heating system. After reading the Rotex brochure, I noticed the high electricity demand.

My current idea: bungalow with solar thermal energy + air-to-water heat pump + photovoltaic system with electricity storage. The photovoltaic system should largely supply the electricity for the air-to-water heat pump and charge the electricity storage. Since I have not yet experienced how loud this outdoor unit can really be, I also find solar thermal energy on the roof quite good.

Questions about my thoughts:
1. Does this constellation make sense for a build in Brandenburg, around Zossen/Königs Wusterhausen?
2. Or would the solar thermal energy be "superfluous"?
3. What costs should one roughly expect for each option?

The goal is a KfW55 bungalow heated as efficiently as possible. Although I do not know yet if photovoltaic and air-to-water heat pump alone are sufficient for this.

Best regards
Peter

Oh yes, I almost forgot. A fireplace is also to be used in the living room. It might possibly reduce the electricity demand for the air-water heat pump during the cold season with little sun.

Hello first of all.
This cannot be clarified in one sentence.
Personally, I would forego solar thermal, as a buffer is required for it. Furthermore, it is not so easy to regulate because the heat pump is designed for the lowest possible temperature. With solar thermal, the temperatures are generally high. This then has to be mixed down to support the heating.
I consider a heat pump with photovoltaic to be sensible. The photovoltaic supplies the electricity in summer for the preparation of hot water.
With KfW55 and your living area, the energy demand of the heat pump should be limited, provided everything is correctly designed.
You will probably never save with the fireplace. The installation already costs quite a bit. Additionally, you also have ongoing costs.
However, the heat is pleasant. So I would consider the fireplace a luxury item.

Thank you for your opinion. Yes, the fireplace is planned anyway, as a luxury. Regarding the buffer, I thought it was necessary anyway because of the underfloor heating. In the show house with Rotex system, there was also a large water storage tank in the utility room. During our visit, the temperature on the roof was 125 degrees and the stratified storage tank was able to store a lot as a result. I also just saw that a provider offers the house as a Kfw 40 Plus house with [Luft-Wasser-Wärmepumpe], [Photovoltaik-Anlage] and [Li-Ion Speicher].

If during your visit the collector showed 125 °C, then the system was not working. This is often a problem with solar thermal systems. Usually air in the system. Solar thermal with heat pump is not really sensible anyway; better to make the photovoltaic system as large as possible, that is more effective. If you can afford air-water heat pump + photovoltaic + storage, that is the best long-term solution for low energy costs.

Thank you, I have just read a bit about the storage systems. The costs for them are not insignificant. Reports from the last 3 years show that the break-even point is reached after about 20 years. However, the batteries usually need to be replaced then. The prognosis might be better today. For that, I would probably have to talk to a solar specialist.