We haven’t had a single day of sun in the last 2 weeks. Therefore, no solar gains either. If we didn’t heat for a few hours every day, the indoor temperature would be around 18 degrees. That is no longer comfortable and not possible that way.
We are not talking about photovoltaics here but gains through the windows.
Just because the sun is not burning summer-like from the blue sky doesn’t mean it isn’t shining and no solar gains are taking place. clarified this by referring to the photovoltaic output. Sometimes you’re surprised when you look up as a human and see a cloudy sky, yet the photovoltaics still run at 30% capacity. Be that as it may, if it doesn’t work for you, it just doesn’t work. For us it works. There are no comfort losses because the heating would turn on if the indoor temperature deviates too far from the setpoint.
Just because the sun is not burning summery from the blue sky doesn't mean it isn't shining and there are no solar inputs. made this clear with the reference to the photovoltaic yield. Sometimes you’re surprised when you look up as a person and see a cloudy sky, yet the photovoltaic still runs at 30% performance.
Be that as it may, if it doesn’t work for you, it just doesn’t work. For us, it works. There are no comfort losses because the heating would come on if the indoor temperature deviated too far from the setpoint.
That may be true for your photovoltaic system, but with the windows it’s practically useless for you.
I once made a calculation out of interest for my case to see whether gas - air-water heat pump - brine-water heat pump would be more economical.
Framework conditions:
Air-water heat pump annual performance factor 4.0
Brine-water heat pump annual performance factor 5.5
current energy prices (electricity 23 cents, gas 5 cents)
investment from my offers from a few years ago
subsidies considered
220 m² heated area KFW55 (consumption value 4500 kwh heat amount)
consideration period 15 years
1st place: Gas approx. 1300 Euro
2nd place: Air-water heat pump approx. 1800 Euro
3rd place: Brine-water heat pump approx. 2200 Euro
Confirms that gas is still the cheapest by a ! large ! margin. What really shocked me was that the brine heat pump would have cost almost twice as much in my case.
Am I correct in assuming that the comparable calculation for a smaller area (say 120-150 sqm) would look different or shift in favor of the heat pump? After all, the fixed costs for gas (meter, chimney sweep...) would weigh more heavily here!?