Thanks for the hint (radiation), but with radiation the surface area must also be relatively large, which is difficult to achieve with warm water pipes. With a high pipe density, the suspension must also be more complex than if the pipes are attached to the floor. If then a cladding is applied (to hide the pipes), the efficiency will certainly decrease further. Therefore, in practice this is surely offered more as an electric panel, which I also have not seen much of, so I do not consider it, as the effort is not reasonably proportionate. (My subjective opinion)
Currently ~8° average outside temperature - inside everything 21°C / Postal Code Berlin / Wall 25cm Ytong plastered,
Flow 50° return 25° // Ground floor area ~120m² underfloor heating // Roof ~50m² radiators (not all heated) oil consumption only winter (summer off, hot water electric) 1,800 liters
Hot water nonsense--why? I practically tested and found that even on the west side (at least during summer operation) I generate enough hot water to shower. I now make my hot water electrically with an average of 3 kW per day.
30 days 90 kW (30 ct) = 27,-€ per month. Summer 6 months = 162,-€
Flat collector (cheap version Cu-Aluminium - was also my test device) 180,- 3 pieces = 540,-
540,- divided by 162,- p.a. = 3.3 years.
Seems manageable and acceptable to me. Payback times of >15 years, which extend further with repairs, are unacceptable to me (who knows if I will still experience that!?) and in my opinion are something for bankers or futurists. The former already proved (in 2008) how precisely they know everything.
In anticipation of criticism of the calculation above: Yes, I know, no installation is included and that is not entirely accurate. But I am a semi-DIY expert and can do that easily. I feed this directly into the heating coil of the hot water boiler since the heating does not run in summer, so I also save the heat exchanger, which would also cause losses.
The photovoltaic system, often praised here as "great," I have ruled out for now, after having studied all the information. Even Prof. Quaschning (following link) , who calculates thoroughly, must recognize that the kW outputs in our latitudes are not necessarily the best. Looking back at the past, as profits declined due to reduced electricity feed-in, I am also skeptical about the future. Optimizing with VAT refunds and small business taxation does not help here either.
As often posted here, it is not done with an Excel sheet!
[MEDIA=YouTube]3F_5hljAKjI[/MEDIA]
By the way: An acquaintance recently told me he had yet another unexpected expense. He had his photovoltaic system washed with distilled water, because he was told it was good to restore the efficiency to the original value. I don’t know if it was the usual scammers or if it actually makes sense.
Therefore: greetings to the photovoltaic users, who today, when looking out the window, only have tears when they look at their meter. (At least it’s raining here)
Don’t be sad, the rain will at least wash your panels clean.