ᐅ Gas with solar thermal? Or heat pump with photovoltaic? Advice needed

Good morning to the forum,
I have been researching heating options for quite some time and have gathered a few opinions, which have only made me more uncertain about my decision. That’s why I thought I’d ask the forum.

My family (2 adults, 1 child) is planning to build the following single-family house at the end of this year or beginning of next year:

Single-family home with pitched roof
Approximately 115 m² (1,237 sq ft)
Solid construction (calcium silicate brick ground and upper floors, brick-clad)
No KFW standard
Building location: southern Mecklenburg

Unfortunately, I can’t provide an energy performance certificate or heating load calculation yet, as the preliminary offer is still being prepared. I am also aware that a general statement can’t really be made since every house and heating behavior is individual.

The construction company advised us to install a modern hybrid heating system consisting of a gas condensing boiler and two solar thermal panels on the roof for domestic hot water, as the initial costs are relatively low (plus installation of the central gas connection), and this technology has proven reliable. The entire house is planned to have underfloor heating. According to the company, they have had very positive experiences with this and consider the technology future-proof. (There is also the idea of a fireplace in the living room.)

On the other hand, I think gas prices will not get any cheaper in the future, and the topic of CO₂ taxes (especially concerning the fireplace) worries me somewhat.

In theory, I would prefer to install a geothermal heat pump combined with a suitable photovoltaic system because this would make me independent of fossil fuels and allow me to heat “off-grid” to a certain extent, depending on efficiency. However, I am hesitant because of the very high initial costs and don’t really know how these compare to operational costs. I also can no longer realistically assess which technology offers the best cost-performance ratio (except for air-source heat pumps).

As you can see, I am completely undecided and hope to get some feedback and expertise from the forum.

Thanks in advance for your replies.

Micha8589 schrieb:

According to the company, they have had very good experiences with this and this technology is still future-proof today.

Then you should follow that advice. Nothing is worse than a partner who is not familiar with heat pumps and installs something that “somehow” works.

Gas condensing boilers are mature technology and state of the art. Even ten or fifteen years ago, there were predictions that gas would become obsolete and prices would rise, and so on. Years later, little has changed. Gas is still up to date.

Yes, solar thermal is not really worth it, but with a basic solar system you have almost no investment costs and get three quarters of the year warm/hot water from the roof.

Regarding the CO2 tax until 2025, this means about €60 additional cost per year for an average household. After 2025, up to about €120. More efficient heating systems/houses according to stricter regulations like the energy saving ordinance pay less. However, electricity for the heat pump generally will not become cheaper.

Micha8589 schrieb:

(The idea of a fireplace in the living room is also being considered)

If you are planning to build a modern house, possibly at or above the energy saving ordinance standard, you might want to reconsider this idea. Fireplaces generally cause overheating in modern houses, and the investment deserves thorough consideration.

We faced the same decision four years ago. We chose gas plus solar. It was and still is more cost-effective for both installation and operation. We are very satisfied.

At the end of the day, the whole issue is basically a gamble.
Of course, media-triggered spikes against gas are noticeable.
But is the heat pump really a cure-all in every situation?
With a well-adjusted system, the costs are actually not that different.

I agree with Mycraft; it is important that your heating supplier knows "their" system well.
There are plenty of reports about heat pumps that cycle to death...

A smartly designed air-to-water heat pump combined with photovoltaic panels is the better choice.
Adding a shower pipe for 600 € makes heating even more affordable.
A heat pump plus underfloor heating requires more careful planning, which honestly is not a given.

I am facing the same question.

Gas condensing boiler and controlled mechanical ventilation with heat recovery
or heat pump and horizontal ground heat exchanger.

Both designed with underfloor heating set at 30/28°C (86/82°F) and wall heating in the bathrooms.

Advantages of gas
Mature technology
Fault-tolerant in heating system design
Equipment is affordable
Every heating engineer is familiar with it
Lower operating costs

Disadvantages of gas
Uncertainty regarding politically driven price developments
Chimney sweep inspection every 3 years

Advantages of heat pump
Can partially benefit from photovoltaic systems
Some cooling capability

Disadvantages of heat pump
Heating system and heat pump must be perfectly designed
Uncertainty about electricity price developments
Higher equipment costs
Heating engineer must have excellent expertise

My tendency is clearly leaning towards gas, although the heat pump concept does spark my interest.