Air heat pump or use gas and solar?

It was like this here. And before the start of construction, I received this along with the statics. I also remember the cross with compliance with the Energy Saving Ordinance in the permit application. However, we did not change anything at all in the execution planning, which was created after the building permit was granted. No window was moved, no wall altered. And I am very glad that we proceeded this way. Because here in the settlement there are at least two characters who immediately run to the building authority with every supposed irregularity and every alleged B plan violation and enforce construction stops. No chance with us. Since we are talking about a [Solaranlage Hotzenplotz] here, I would like to add that I do care whether this system complies with the rules or not. Because it costs something. I have to take it, but it is not free. Then I also want it to do what it claims to do, namely provide hot water. As much as possible. I’ll say it again, since mid-March our solar system, which faces SSW and is tilted at 30 degrees, can almost completely supply our hot water on its own; the light is sufficient. It can do this until mid-September. So half a year. Even in January with clear air it provided hot water. Why not tilt the 15-degree roof a bit! So that it works! The storm argument is nonsense. Then the BU should attend some training on how to securely fasten something on the roof against storms. That’s possible. Karsten

Why not angle something on the 15-degree roof!

Because it looks awful. We would rather use a brine heat pump. Building a 15° roof and then angling solar collectors more steeply cannot be the aesthetic solution.

Since it's only about 100 kWh difference per year (15 or 30°), I didn't care.

Results from the Junkers solar simulator:


15° tilt:
Collector: 6.65 + 6.65 m² Junkers VK230-1
Characteristic curve: eta0 = 0.745 a1 = 2.007 W/(m²·K) a2 = 0.0050 W/(m²·K²)
Tilt: 15.0/15.0° South deviation: -45.0/45.0°
System type: Domestic hot water
Storage: SK 300-5 solar (290 liters)
Temperature: Max. 85°C
min. 52°C
Heat demand: 15.70 kWh/day = 300 liters/day from 10°C to 55°C

Month Solar Radiation External Coverage Efficiency
yield energy energy rate**** degree
[kWh] [kWh] [kWh] [%] [%]****
January: 123 382 374 25 32
February: 201 610 270 43 33
March: 397 1274 113 78 31
April: 449 1668 48 90 27
May: 490 2218 28 95 22
June: 473 2158 28 95 22
July: 504 2447 12 98 21
August: 499 2210 11 97 23
September: 441 1418 56 89 31
October: 328 942 171 65 35
November: 151 433 330 31 35
December: 84 258 394 17 32
Total: 4139 16018 1834 69 26

Specific collector annual yield: 311 kWh/m²


30° tilt:
Area: 6.65 + 6.65 m² Junkers VK230-1
Tilt: 30.0/30.0° South deviation: -45.0/45.0°
System type: Domestic hot water
: 15.70 kWh/day = 300 liters/day from 10°C to 55°C
Conv. energy: Natural gas condensing boiler
Efficiency: 103% / 85% / 70% during operation in winter / spring, autumn / summer

Month Solar Energy CO2
yield savings savings
[kWh] [kWh] [m3 gas] [kg]****
January: 146 141 0 0
February: 225 219 0 0
March: 406 444 0 0
April: 448 527 0 0
May: 488 587 0 0
June: 471 673 0 0
July: 503 719 0 0
August: 498 712 0 0
September: 445 552 0 0
October: 356 419 0 0
November: 177 196 0 0
December: 101 98 0 0
Total: 4264 5285 1 2

In this no-frills scheme, mounting at 30 degrees instead of 15 degrees yields a full 100 kWh more solar yield with 10 collectors. 5 on one side, 5 on the other.



Regardless of the economically negligible difference, it is absolutely important to me that everything is legally compliant.

And I am very glad to have proceeded this way. Because here in the settlement there are at least two people who immediately run to the building authority with every supposed irregularity and every supposed violation of plan B and obtain construction stops. No chance with us.

I can only agree with that. Better to invest a few euros more and obtain a building permit instead of relying on exemption from approval. For the reasons mentioned. The same with the neighboring property, but a justified case. He thought he could build however he wanted and that setback areas, parking regulations etc. were just recommendations. A call to the building authority in September, immediate construction stop. Since then the construction site has been standing. If he had applied for a building permit, he at least would not have started building and now have to finance the half-finished construction site... Solar panels would not be an option for us at 7 degrees, and mounting them raised, in my opinion, looks like trying and failing on a pitched roof. The experts then mount them on the facade [emoji849] Either raised on a flat roof (which I would still find aesthetically acceptable), or like Karsten on the roof surface (which would be my preference) or with a shallow pitched roof consider something without solar thermal...

Because that looks ugly. Then we would rather take a brine heat pump. Building a 15° roof and then angling solar collectors more steeply cannot be the aesthetic solution.

Good man [emoji1303][emoji4]

ok, convinced. Hardly makes any difference to angle it. And? Does he manage to calculate it? If you want to build absolutely according to the rules, it must also work out with 15 degrees in the [Wärmenachweisbrechübungsheft].

And? Does it get calculated?

The GÜ has now offered it to me like this and asks for confirmation. Previously, the appointed installer promised me to check it after we had spoken on the phone that angling is out of the question. Therefore, I assume that everything is fine.

I can request the thermal insulation verification and inform that I want to review it before I commission a specific heating system definitively.

ok, convinced. Barely makes sense to angle.

Neither 300 kWh nor 400 kWh helps anyone further. That's simply a joke. It's only done so that it's good. There will be even less yield because the initially 10m² of collectors is now reduced to three elements, as more do not fit because of the chimney. The 10m² were four collectors.