Prefabricated house heating: Gas / Air heat pump / Underfloor heating

I agree with this argument:

Dazu dann die Frage, wann denn die meiste Energie benötigt wird, die hier gewonnen wurde. Wie gut kann man sie speichern?

I doubt the other argument

Vorsicht - es zählt die gesamte Einstrahlung über den Tag. Da sind Ost- und Westseite schon gar nicht mehr so schlecht, insbesondere bei steileren Dächern.

I would claim: The steeper a roof is, the more important the south orientation becomes.

A photovoltaic calculator on the web showed in a sample calculation that with a 25-degree roof, a west-east roof has 14% less irradiation compared to a south roof, and with a 38-degree roof, a west-east roof has 24% less irradiation compared to a south roof.

The fact is also that only ¼ of all offered plots are purely south-facing.

Pure north-facing locations work too, just use the other side of the roof...

(At least, if we're talking about gable roofs...)

There are also intermediate gradations, e.g. southwest or northeast orientation of the two roofs.

I maintain that a south/north orientation of the two roofs is best and west/east orientation is the least favorable. Whether that is still profitable, I cannot assess and it probably depends on the individual case.

To my knowledge, in larger solar systems for heating support, the modules are sometimes installed steeper and on the west side. The reason is that during heating times the sun is lower, while in summer the small amount of hot water can be easily produced with the steeper installations. Whether this is similarly useful for photovoltaics, I do not know.

in my opinion, he makes a mistake on his site by grouping the air-water heat pump under the category air heat pumps.

Mr. Zimmermann does distinguish on his site between air-water heat pump (air-water heat pump) and air-air heat pump (air-air heat pump), he just names them strangely: air heat pump or ventilation heat pump. The air-air heat pump fares even worse in his view than the air-water heat pump, but the model house used is also a KFW-100 house. For passive houses or KfW-40 houses, air-air heat pumps are certainly a very cost-effective solution. There are indeed some strange posts on his site, but his sample calculations are unique on the WWW and do not seem so bad to me, even though one must of course consider that such a calculation will yield different results with other conditions (living space, basement yes/no, insulation, climate region, other craftsman prices, assumptions about price increases for electricity, gas, etc.). However, one can get a sense of the approximate costs of the various systems and the relationship between running costs and investment costs by studying the tables.

To my knowledge, in larger solar systems for heating support, the modules are sometimes installed steeper and facing west. The reason is that the sun is lower during heating periods, while in summer the little hot water can be easily produced with the steeper installations.

Whether this is similarly useful for photovoltaics, I do not know.

Yes, with solar thermal systems, a west/east orientation can be advantageous because people tend to shower in the morning and evening. Steeper roofs are also good in that case because the sun is low in the morning and evening. The whole system works optimally when the roof is perpendicular to the sun’s rays.

For photovoltaics, where electricity is generated and fed into the grid throughout the day, a south orientation is better. In our latitudes, a roof pitch of 30 degrees is optimal for that, but the yield does not get much worse if it is 20 degrees or 40 degrees.

For photovoltaics, where electricity is generated and fed in throughout the day, a south-facing orientation is better. For this, in our latitudes, a 30-degree roof pitch is optimal, but the calculation does not get much worse if it is 20 degrees or 40 degrees.

With the addition: 'when fed in' – then you have to calculate: when and how much is fed in, and what the overall balance looks like over the year. However, this mainly depends on individual consumption behavior. Only when a large part of the energy is temporarily stored for individual use can you generalize again and consider the 30° south orientation as the best possible alignment.

But this leads somewhat away from the topic.
Air-to-water heat pump / geothermal energy (probe or surface?) / gas is always a question strongly dependent on the location.
In our case: the plot would be too small for surface geothermal energy, probe is not allowed (would not be approved), and the distance to the nearest gas line is about 35m. All this in the mildest region of Bavaria... Therefore, the air-to-water heat pump was the more affordable solution. Photovoltaics would be possible (30° south-facing orientation) but currently not economical due to a too low share of self-consumption.