Experience with KFW55 solid + gas + 5 sqm solar

I have taken a look at your numbers and have a few more questions.

Where is the house located or what is the standard outdoor temperature?

You surely still pay a basic fee for gas. For new contracts, I find about €220 depending on the provider in the tariff comparison.

Do you have a heat pump tariff for electricity?

You have a controlled ventilation system with heat recovery. How high are the incidental costs? Maintenance, cleaning, filters, and electricity consumption?

Heat pump maintenance? Heating maintenance? Chimney sweep costs?

Unfortunately, these costs still come on top regardless of how high the consumption is.

At €28 in costs per month, we won’t get any lower quickly without significant investments.

Where is the house located or what is the standard outside temperature?

At around 300 meters above sea level, rather exposed to wind, not in a city center, rather outside near fields

You certainly still pay a basic price for gas.
For new contracts I find about €220 in the tariff comparison depending on the provider.

Gas:

Consumption assumption	4,000 kWh/year
x	Price per kWh gross (net)	9.70 (9.07) Ct./kWh
=	Total price for consumption	€388.00/year
+	Basic price gross (net)	€150.00 (140.19)/year
=	Gross price without bonus in the 1st year	€538.00/year
	Average per month	€44.83/month
-	Immediate bonus	€10.00
-	New customer bonus	€40.00
=	Gross price including bonus in the 1st year	€488.00/year
	Average per month	€40.67/month

Electricity:

Consumption assumption	3,950 kWh/year
x	Price per kWh gross (net)	26.60 (22.35) Ct./kWh
=	Total price for consumption	€1,050.70/year
+	Basic price gross (net)	€151.89 (127.64)/year
=	Gross price without bonus in the 1st year	€1,202.59/year
	Average per month	€100.22/month
-	New customer bonus	€50.00
=	Gross price including bonus in the 1st year	€1,152.59/year
	Average per month	€96.05/month

Do you have a heat pump tariff for the electricity?

No

You have a controlled ventilation system with heat recovery.
How high are the ancillary costs?
Maintenance, cleaning, filters and electricity consumption?

It is a decentralized ventilation system.
4 devices with heat recovery
3 devices in wet rooms that only vent to the outside.
Cleaning: a cloth and soap, so nothing
Filter: €20 every 5 years
Electricity consumption: about 140 kWh electricity, so €37/year

Maintenance heat pump?

First small defect after one year. A condensate pump, under warranty, otherwise it would have been €120.
The refrigeration technician wants to come every 2 years after the heating period in spring. I estimate the costs at €450, but I cannot say exactly yet.
A climate compressor in the outdoor unit lasts about 8 years, so €1,250 is planned for the year 2030.
That makes a planned maintenance cost of €3,050 until the 12th year.

Maintenance heating?

First maintenance done after 9 years for €1,151, a few parts had to be proactively replaced. This also included the maintenance of the solar storage, a new sacrificial anode.
He would like to come annually, but I do not agree. I have now planned €400 every 2 years. That should definitely be enough.

Chimney sweep costs?

Last time €89, for gas it only needs to come every 3 years.