Air heat pump or use gas and solar?

The question is whether the tubes are so much more expensive that the lower price for inefficient flat-mounted flat collectors "pays off" or whether despite the higher price a more reasonable cost-/benefit ratio is achieved by using tube collectors. Unfortunately, I only received the two pictures.

It won't pay off anyway. It's a solar thermal system with 5-8 sqm. Nothing pays off there. (I have one myself) Nevertheless, the system delivers a lot of hot water in summer. Also, the efficiency from flat-mounted to tilted (I'm now going out on a limb) is only marginally worse. I drive through the city daily and see the same 5 sqm systems on the newly built "city villas." In other words, they are usually installed that way.

With us, no mounting on supports would be suggested either if we didn’t have just a 15° roof pitch. I also don’t see such a roof with a non-supported flat roof collector in the picture now.

Welcome to the new building districts of Berlin, that's all I have to say (to the picture). This is even one of the "better" ones.



A roof with only 15° pitch is not in the picture, but you can see that the systems are scattered all over the place and mainly oriented to the west.

What I'm getting at:

If you now have your system built with 15° facing south, then you have at least the same values as most of the ones in the picture with their west-facing systems and 30-45° etc. and those are approved and built without any problems.

Be-Plan decides on two stories, and every builder happily builds some kind of standard villa... I can't really call any of them truly nice.

There wasn’t really a Be-Plan there. Practically anything that fit the drawer was allowed to be built.

Who would voluntarily build 1.5 stories when two are allowed?

I did. Two-story houses like in the picture are just a horror. I’d rather have pitched roofs.

There is only a 3-meter strip of land around every house. I find that creepy.

Yes, something like that. Back then we also considered building there (or buying the lemon-yellow one at the top center). It was a huge area and in 2006 everything still started out quite reasonable. In the end, it’s now around 500 houses. The interesting thing is, every year the plots got smaller, but the houses built on them got bigger.

That was the beginning in 2006, as I said still quite reasonable:

What is actually to be made of a heating system like the Viessmann Vitocaldens 222-F?

A combination of an air-water heat pump and a gas condensing boiler. You can program the current electricity and gas prices, and the device selects the most economical mode of operation itself. Sounds great. I didn’t know that before. And you can do without the expensive solar collectors.

I think you didn't want an external device. In itself, that sounds interesting. However, I can't contribute any experience.